Surgical instrument kit

Abstract

The present invention relates to a surgical kit of parts comprising the following instruments: • a guide wire (a1) having a drill tip (a2); • a cartilage punch (b1) with an axial hole (b3) with a circular geometry in the radial direction over the whole length such that the guide wire (a1) can be slid through the axial hole (b3) of the cartilage punch (b1), wherein the hollow cylinder (b2) forms at one end (b4) a circular cutting edge (b5) with an external diameter Db,external and an inwardly tapered circular cutting wall (b6); and • a bone milling drill (c1) with an axial hole (c3) having a circular geometry in the radial direction over the whole length, wherein one end (c4) of the hollow cylinder (c2) has the form of an end milling cutter (c5) with an external diameter Dc,external, with the proviso that the guide wire (a1) can be slid through the axial hole (c3) of the bone milling drill (c1) and with the further proviso that the external diameter Db,external of the circular cutting edge (b5) of the cartilage punch (b1) equals the external diameter Dc,external of the end milling cutter (c5) of the bone milling drill (c1). The invention further pertains to a method of repairing an (osteo)chondral defect of the knee in a subject with the surgical kit.

Description

[0001] SURGICAL INSTRUMENT KIT

[0002] TECHNICAL FIELD

[0003] The present invention pertains to a surgical kit of parts and further to a method of repairing an (osteo)chondral defect of the knee in a subject with the surgical kit of parts.

[0004] BACKGROUND OF THE INVENTION

[0005] Damage to the articular cartilage in the knee joint, to the underlying bone or to both may result in a number of diseases or conditions. Such damages are often referred to as (osteo)chondral defects in the knee joint. A chondral defect refers to a focal area of damage to the articular cartilage, i.e. the cartilage that lines the end of the bones. An osteochondral defect refers to a focal area of damage that involves both the articular cartilage and a piece of the underlying bone. These defects can occur from an acute traumatic injury to the knee or an underlying disorder of the bone.

[0006] Early symptoms in patients having cartilage and / or underlying bone lesions may be treated with non-surgical or surgical treatments. Surgical treatments include for example open or arthroscopic drilling, debridement, bone marrow stimulation, bone grafting, chondrocyte implantation, osteochondral grafting and applying osteochondral implants.

[0007] A combination of arthroscopic drilling a hole at the site of the defect through the cartilage into the underlying bone followed by applying an osteochondral implant into the drill hole has been shown to be a promising therapy for cartilage and bone regeneration or repair in knee joints. To facilitate introduction and a tight fit of the osteochondral implant within the bone tissue, the hole that is first created within the bone tissue typically has a diameter similar or slightly smaller than the diameter of the implant that is to occupy the hole, ensuring a tight fit within the implant region. In order to avoid dislodging of the implant and improve the healing process of the defect it is of utmost importance to be able to create a hole within the bone tissue at the exact spot of the (osteo)chondral defect and with the indented geometry and orientation with respect to the articular surface. Methods for introducing osteochondral implants within the bone tissue of the knee joint and surgical instrument kits for use in these methods have been described in the prior art.

[0008] EP2916779A1 for example discloses a surgical instrument kit for implanting osteochondral implants within a hole applied in bone tissue. US2021 / 0244853A1 also discloses a surgical instrument kit for implanting solid substrates within a hole applied in bone tissue. In this respect, reference is made to Figures 2 to 9 of US2021 / 0244853 Al.

[0009] In order to prepare a hole in the bone of a knee joint at the site of an (osteo)chondral defect, one first has to drill through the articular cartilage layer that covers the bone. The inventors have established that drilling through the layer of articular cartilage results in a frayed edge where the drill bit cuts the cartilage. In other words, drilling at the place of the (osteo)chondral defect may result in additional damage to the cartilage, which is of course undesirable. Moreover, the frayed edge may complicate the insertion of the implant and may adversely affect the subsequent healing process. In other words, the surgical instrument kits and methods proposed in the prior art lead to irregularities in terms of hole geometry and / or to damage to the surrounding tissue at the insertion site.

[0010] It is an object of the invention to provide a surgical instrument kit and a method for repairing an (osteo)chondral defect of the knee in a subject by insertion of an implant leading to less irregularities in terms of hole geometry and / or to damage to the surrounding tissue at the insertion site.

[0011] It is a further object of the invention to provide a surgical instrument kit for repairing an (osteo)chondral defect of the knee in a subject by insertion of an implant, facilitating easy insertion of the implant into the desired tissue at the correct orientation, wherein the implant can be firmly attached to the surrounding tissue.

[0012] SUMMARY OF THE INVENTION

[0013] The inventors have established that one or more of the objectives can be achieved by providing a cartilage punch having a circular cutting edge with a diameter that is equal to that of the bone milling drill that is used to drill the actual hole for insertion of the implant and by forcing the circular cutting edge into the cartilage, preferably through the cartilage until the underlying bone is reached, before the bone milling drill is applied to provide the actual hole.

[0014] By directing the circular cutting edge of the cartilage punch towards the (osteo)chondral defect of the knee and forcing the circular cutting edge into the cartilage, preferably through the cartilage until the underlying bone is reached, a sharp-edged cylindrical cut, i.e. without frayed edges, is formed in the cartilage, preferably through the cartilage. Subsequent careful application of the bone milling drill within the contour of the sharp-edged cylindrical cut provides a drill hole for implantation without producing a frayed cartilage edge around the hole opening. Accordingly, in a first aspect, a surgical kit of parts comprising the following instruments is provided:

[0015] • a guide wire (al) having a drill bit tip (a2), a circular cross section and an external diameter Da, external in the radial direction and a length Lain the axial direction;

[0016] • a cartilage punch (bl), being a hollow cylinder (b2) with a length Lb in the axial direction, said hollow cylinder (b2) having an axial hole (b3) with a circular geometry in the radial direction over the whole length, wherein the hollow cylinder (b2) forms at one end (b4) a circular cutting edge (b5) with an inwardly tapered circular cutting wall (b6), wherein said circular cutting edge (b5) has an external diameter Db, external in the radial direction and wherein the axial hole (b3) has an internal diameter Db, internal, with the proviso that Db, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (b3) of the cartilage punch (bl); and

[0017] • a bone milling drill (cl) being a hollow cylinder (c2) with a length Lcin the axial direction, wherein the hollow cylinder (c2) has an axial hole (c3) having a circular geometry in the radial direction over the whole length with a diameter Dc, internal, wherein one end (c4) of the hollow cylinder (c2) has the form of an end milling cutter (c5) with an external diameter Dc, external, with the proviso that Dc, internal equals Da, external, such that the guide wire (al) can be slid through the axial hole (c3) of the bone milling drill (cl) and with the further proviso that the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl).

[0018] In a second aspect, a method of repairing an (osteo)chondral defect of the knee in a subject with the surgical kit of parts according to the first aspect is provided, said method comprising the steps of:

[0019] (i) exposing the cartilage of the articular surface of the knee joint of the subject, said knee joint having an (osteo)chondral defect;

[0020] (ii) forcing the drill bit tip (a2) of the guide wire (al) into the cartilage and into the underlying bone, such that the guide wire (al) is fixed substantially perpendicularly to the articular surface;

[0021] (iii) sliding the cartilage punch (bl) over the guide wire (al) with its circular cutting edge (b5) directed towards the defect and forcing the circular cutting edge (b5) into the cartilage, preferably through the cartilage until the underlying bone is reached, to form a sharp-edged cylindrical cut in the cartilage, preferably through the cartilage;

[0022] (iv) removing the cartilage punch (bl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;

[0023] (v) sliding the bone milling drill (cl) over the guide wire (al);

[0024] (vi) drilling a cylindrical hole into the cartilage and into the underlying bone with the bone milling drill (cl), wherein the hole has a diameter Dc, external and a depth E;

[0025] (vii) removing the bone milling drill (cl);

[0026] (viii) removing the guide wire (al); and

[0027] (ix) positioning a cylindrical implant (gl) having a length equal to depth E minus between 0.3 and 0.7 mm and having a circular cross section and an external diameter of Dc, external + between 0.05 and 0.20 mm in the radial direction, into the hole obtained in step (viii).

[0028] BRIEF DESCRIPTION OF THE FIGURES

[0029] Figures 1 A to 1C depict guide wires (al) that are part of the surgical kit of parts according to the invention.

[0030] Figures 2 A to 2C depict cartilage punches (bl) that are part of the surgical kit of parts according to the invention.

[0031] Figures 3 A and 3C depict bone milling drills (cl) that are part of the surgical kit of parts according to the invention.

[0032] Figures 4A to 4C depict sizer-positioners (dl) that can advantageously be used with or incorporated in the surgical kit of parts according to the invention.

[0033] Figures 5 A to 5C depict drill sleeves (el) that can advantageously be used with or incorporated in the surgical kit of parts according to the invention.

[0034] Figures 6A to 6C depict trial inserts (fl) that can advantageously be used with or incorporated in the surgical kit of parts according to the invention.

[0035] DEFINITIONS

[0036] The instruments defined in the present invention are elongated articles, i.e. having a length that is much longer than the diameter. The direction along the length is called the ‘ axial direction’ throughout this document. The direction along the diameter of the instruments, which is perpendicular to the axial direction is called ’radial direction’ throughout this document.

[0037] The term ’(osteo)chondral defect of the knee’ as used herein has the common meaning in the art and refers to both chondral defects and osteochondral defects of the knee. A chondral defect refers to a focal area of damage to the articular cartilage, i.e. the cartilage that lines the end of the bones. An osteochondral defect refers to a focal area of damage that involves both the cartilage and a piece of the underlying bone.

[0038] DETAILED DESCRIPTION

[0039] Surgical kit of parts

[0040] A first aspect of the invention concerns a surgical kit of parts comprising the following instruments:

[0041] • a guide wire (al) having a drill bit tip (a2), a circular cross section and an external diameter Da, external in the radial direction and a length Lain the axial direction;

[0042] • a cartilage punch (bl), being a hollow cylinder (b2) with a length Lb in the axial direction, said hollow cylinder (b2) having an axial hole (b3) with a circular geometry in the radial direction over the whole length, wherein the hollow cylinder (b2) forms at one end (b4) a circular cutting edge (b5) with an inwardly tapered circular cutting wall (b6), wherein said circular cutting edge (b5) has an external diameter Db, external in the radial direction and wherein the axial hole (b3) has an internal diameter Db, internal, with the proviso that Db, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (b3) of the cartilage punch (bl); and

[0043] • a bone milling drill (cl) being a hollow cylinder (c2) with a length Lcin the axial direction, wherein the hollow cylinder (c2) has an axial hole (c3) having a circular geometry in the radial direction over the whole length with a diameter Dc, internal, wherein one end (c4) of the hollow cylinder (c2) has the form of an end milling cutter (c5) with an external diameter Dc, external, with the proviso that Dc, internal equals Da, external, such that the guide wire (al) can be slid through the axial hole (c3) of the bone milling drill (cl) and with the further proviso that the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl).

[0044] In a preferred embodiment, the generalized wording ‘Dx, internal substantially equals Dy, external, such that Y can be slid through X’ or similar means that ‘Dy, external is between 98% and 99.99% of Dx, internal more preferably it means that ‘Dyexternal is between 99.5% and 99.9% of x, internal • As indicated hereinbefore, the surgical kit of parts at least comprises a guide wire (al), a cartilage punch (bl) and a bone milling drill (cl). The kit of parts, however, preferably comprises additional instruments that facilitate providing a hole with the correct dimensions and geometry, easy insertion and firm attachment of the implant into the bone tissue and insertion with the correct orientation.

[0045] The surgical kit of parts as defined herein is preferably provided in a box or in different boxes, such as a cassette, preferably in a box or different boxes that can be subjected, along with the instruments of the kit of parts, to medical sterilization including high-pressure and high temperature steam sterilization. The box is preferably made of (surgical) stainless steel.

[0046] In a preferred embodiment, the mandatory and optional instruments in the surgical kit of parts, such as instruments (al) to (fl) and the hammer, are made of metal, more preferably of (surgical) stainless steel.

[0047] As will be explained in what follows, the surgical kit of parts according to the first aspect is preferably used with a sizer-positioner (dl) and preferably with a hammer or further comprises a sizer-positioner (dl) and / or a hammer.

[0048] One of the first steps in repairing an (osteo)chondral defect of the knee in a subject comprises applying the guide wire (al) into the cartilage and into the underlying bone. This step is preferably performed with help of the sizer-positioner (dl). With help of the sizerpositioner (dl) it is determined what the size (in the radial direction) of the implant should be. This step may thus determine the dimensions of the cartilage punch (bl), bone drilling mill (cl), optional drill sleeve (el) and optional trial insert (fl). In order to avoid unnecessary sterilization, the guide wire (al), optional sizer-positioner (dl) and optional hammer are preferably provided in a first box and the cartilage punch (bl), bone drilling mill (cl), optional drill sleeve (el) and optional trial insert (fl) are preferably provided in a second box. Different boxes with different corresponding sizes of cartilage punch (bl), bone drilling mill (cl), optional drill sleeve (el) and optional trial insert (fl) are envisaged to be able to repair (osteo)chondral defect of the knee of different sizes.

[0049] Guide wire ( al )

[0050] The guide wire (al) has a drill bit tip (a2), a circular cross section and an external diameter Da, external in the radial direction and a length Lain the axial direction.

[0051] The diameter Da, external should be sufficient to provide the guide wire (al) with sufficient strength and stiffness to be able to slide the cartilage punch (bl) and the bone milling drill (cl) over the guide wire (al) and subsequently, respectively, create a sharp-edged cylindrical cut in the cartilage and perform drilling into the underlying bone without breaking or bending of the guide wire (al). In a preferred embodiment, the diameter Da, external is between 1.5 and 3.5 mm, more preferably between 2 and 3 mm, such as about 2.5 mm.

[0052] For practical purposes, the length Lais preferably between 100 and 200 mm, more preferably between 125 and 175 mm, such as about 150 mm. As will be explained in detail below, the length Lamay also influence the length of other instruments of the surgical kit of parts. Likewise, the external diameter Da, external of the guide wire (al) influences the internal diameter of other instruments of the surgical kit of parts that should be able to slide over the guide wire (al).

[0053] The guide wire (al) has two ends (a3, a4) in the axial direction. At one end (a3), the drill bit tip (a2) is provided. The drill bit tip (a2) preferably is a twist drill bit tip. The drill bit tip (a2) typically has a flute or body (a5) that extends along a length between 8 and 30 mm starting from end (a3) in the axial direction. The remaining part of the guide wire (al), i.e. the part not being the flute or body (a5), along the axial direction can be called ‘ shank’ (a6). The shank (a6) can at end (a4) be inserted in for example the Jacobs drill chuck of a drill.

[0054] The guide wire (al) may have one or more line markers (a7,a8) in the radial direction at certain distances apart in the axial direction.

[0055] In an embodiment, the guide wire (al) has a first line marker (a7) in the radial direction at a distance Laifrom end (a3) in the axial direction. Such a line marker can be used to indicate whether the intended drill depth has been reached. If the guide wire (al) is inserted into the bone without the help of a sizer-positioner (dl) as defined below, the first line marker (a7) is to be positioned at a distance Laifrom end (a3) in the axial direction that coincides with the intended drill depth. If during drilling, the first line marker (a7) coincides with the articular surface, the intended drill depth is reached and the drilling process is to be stopped. If on the other hand, the guide wire (al) is to be applied along with a sizer-positioner (dl) as defined below, the first line marker (a7) is to be positioned at a distance Laifrom end (a3) in the axial direction that coincides with the sum of the intended drill depth and the length Ld of said sizerpositioner (dl) in the axial direction. In this embodiment, if during drilling the first line marker (a7) reaches end (dlO) of the sizer-positioner (dl), the intended drill depth is reached and the drilling process is to be stopped.

[0056] In an embodiment, the guide wire (al) has a second line marker (a8) in the radial direction at a distance La2 from end (a4) in the axial direction. Such a line marker can be used to indicate whether the preferred length of insertion in a Jacobs drill chuck of a drill is reached. Exemplary embodiments of the guide wire (al) are presented in Figures 1A to 1C.

[0057] Cartilage punch (bl )

[0058] The cartilage punch (bl) is intended to be used to provide a sharp-edged cylindrical cut, i.e. without frayed edges, in the cartilage, preferably through the cartilage, before drilling a hole into the underlying bone.

[0059] The cartilage punch (bl) is a hollow cylinder (b2) with a length Lb in the axial direction. The hollow cylinder (b2) has an axial hole (b3) with a circular geometry in the radial direction over the whole length. The hollow cylinder has two ends (b4,b7) in the axial direction. The hollow cylinder (b2) forms at one end (b4) a circular cutting edge (b5) with an inwardly tapered circular cutting wall (b6), wherein said circular cutting edge (b5) has an external diameter Db, external in the radial direction and wherein the axial hole (b3) has an internal diameter Db, internal. This cutting edge (b5) is razor sharp. As will be appreciated by those skilled in the art, because of the circular cutting edge (b5) having external diameter Db, external and inwardly tapered circular cutting wall (b6), the internal diameter of the axial hole (b3) will be larger than Db, internal over a certain length Lbi, ultimately reaching about Db, external at end (b4).

[0060] The internal diameter Db, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (b3) of the cartilage punch (bl). As will be appreciated by those skilled in the art, the wording ‘Db, internal substantially equals Da, external in conjunction with ‘such that the guide wire (al) can be slid through the axial hole (b3) of the cartilage punch (blf means that the internal diameter Db, internal is as similar to Da, external as possible with the proviso that the guide wire (al) can be slid through the axial hole (b3) of the cartilage punch (bl) without too much friction. On the other hand, it means that the internal diameter Db, internal is close enough to Da, external to avoid wiggling of the guide wire (al) in the cartilage punch (bl).

[0061] If the guide wire (al) is correctly and firmly positioned in the bone, the cartilage punch (bl) can be slid over the guide wire (al) with its circular cutting edge (b5) directed towards the articular surface with the (osteo)chondral defect and the circular cutting edge (b5) is automatically correctly positioned with respect to the articular surface and the defect. Forcing the circular cutting edge (b5) into the cartilage, preferably through the cartilage until the underlying bone is reached, forms a sharp-edged cylindrical cut in the cartilage, preferably through the cartilage, at the correct spot around the defect and in the correct orientation. As indicated hereinbefore, the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl). The external diameter Db, external of the circular cutting edge (b5) is preferably between 5 and 25 mm, such as between 7.5 and 17.5 mm or between 15.0 and 17.5 mm. It is actually the size of the (osteo)chondral defect that determines the size of the implant in the redial direction and thus the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) and the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl). The kit of parts according to the first aspect can contain more than one cartilage punches (bl) with different external diameters Db, external of the circular cutting edge (b5).

[0062] As will be appreciated by those skilled in the art, the razor sharp cutting edge (b5) of the cartilage punch (bl) may become blunt after prolonged use. Embodiments wherein the cartilage punch (bl) contains two detachable (and thus also attachable) parts are also envisaged. Hence, in an embodiment, the cartilage punch (bl) contains a first part (b8) containing the circular cutting edge (b5) with the inwardly tapered circular cutting wall (b6) and a second part (b9) that is a shaft and that is attached to the first part (b8). After prolonged use, the first part (b8) can be detached from the second part (b9) and a new first part (b8) can be attached to the second part (b9).

[0063] The circular cutting edge (b5) has an external diameter Db, external. As will be appreciated by those skilled in the art, in order to provide a sharp-edged cylindrical cut in the cartilage, the outer diameter of end (b4) must have an external diameter Db, external over a certain length Lbi from end (b4) in the axial direction that is inserted into the cartilage, preferably until the underlying bone is reached. The remainder of the length of the of the cartilage punch (bl) can have a different diameter and can have a non-circular cross section in the radial direction, for example a cross section that provides better grip.

[0064] In a preferred embodiment, the length Lb is between 100 and 180 mm, more preferably between 120 and 150 mm, such as about 130 mm.

[0065] In embodiments, the cartilage punch (bl) is intended to be forced into the cartilage, preferably until the underlying bone is reached, using a hammer. In such embodiments, the length Lb of the cartilage punch (bl) is preferably such that the guide wire (al) does not protrude from the axial hole (b3) at end (b7). In such embodiments, the length Lb of the cartilage punch (bl) is greater than the length Laof the guide wire (al) minus the intended drill depth of the guide wire (al). In embodiment, the surgical kit of parts further comprises a hammer. Exemplary embodiments of the cartilage punch (bl) are presented in Figures 2 A to 2C.

[0066] Bone milling drill ( cl )

[0067] The bone milling drill (cl) is intended to be used to provide a hole with the size of the implant that is to be inserted. The bone milling drill (cl) is to be applied after the cartilage punch (bl) such that a hole is drilled within the contour of the sharp-edged cylindrical cut.

[0068] The bone milling drill (cl) is a hollow cylinder (c2) with a length Lcin the axial direction. The hollow cylinder (c2) has an axial hole (c3) having a circular geometry in the radial direction over the whole length with a diameter Dc, internal. The hollow cylinder (c2) has two ends (c4,c7) in the axial direction. One end (c4) of the hollow cylinder (c2) has the form of an end milling cutter (c5) with an external diameter Dc, external. The internal diameter Dc, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (c3) of the bone milling drill (cl). Moreover, the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl). Since both the cartilage punch (bl) and the bone milling drill (cl) can be slid over the guide wire (al) and since the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5), the end milling cutter (c5) creates a hole that is perfectly within the contour of the sharp-edged cylindrical cut prepared in the cartilage by the cartilage punch (bl).

[0069] In a preferred embodiment, the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl) is between 5 and 25 mm, such as between 7.5 and 17.5 mm or between 15.0 and 17.5 mm.

[0070] As will be appreciated by those skilled in the art, the wording ‘Dc, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (c3) of the bone milling drill (elf means that the internal diameter Dc, internal is as similar to Da, external aS possible with the proviso that the guide wire (al) can be slid through the axial hole (c3) of the cartilage punch (bl) without too much friction. On the other hand, it means that the internal diameter Dc, internal is close enough to Da, external to avoid wiggling of the guide wire (al) in the axial hole (c3) of the bone milling drill (cl).

[0071] In a preferred embodiment, the length Lcis between 100 and 200 mm, more preferably between 125 and 175 mm, such as about 150 mm.

[0072] The length Lcof the bone milling drill (cl) is preferably such that, in use, the guide wire (al) does not protrude from the axial hole (c3) at end (c7) of the bone milling drill (cl). In such embodiments, the length Lcof the bone milling drill (cl) is greater than the length Laof the guide wire (al) minus the intended drill depth of the guide wire (al).

[0073] In a preferred embodiment, the bone milling drill (cl) is to be used along with a drill sleeve (el) that will be defined below. In such an embodiment, the external diameter of the bone milling drill (cl) should not exceed the internal diameter De, internal of the drill sleeve (el) over a length B starting from end (c4) of the bone milling drill (cl), such that the bone milling drill (cl) can be slid through the axial circular through hole (e7) of the drill sleeve (el) over distance B. In such embodiments, length B is greater than Lebecause the bone milling drill (cl) should be forced a certain depth into the bone. More in particular, in such embodiments, length B is preferably greater than Leplus the drill depth of the hole to be applied with the bone milling drill (cl).

[0074] The drill sleeve (el) can be advantageously used to limit the drill depth of the hole to be applied with the bone milling drill (cl) to a predefined value, for example if the depth the bone milling drill (cl) can be forced into the bone is physically limited by the drill sleeve (el). Moreover, the drill sleeve (el) provides additional stability during drilling.

[0075] In a preferred embodiment, the bone milling drill (cl) has a zone (c6) wherein the external diameter exceeds the internal diameter De, internal of the drill sleeve (el) over a length C starting from a distance from end (c4) equal to length B, such that the bone milling drill (cl) can be slid through the axial circular through hole (e7) of the drill sleeve (el) only over a distance from end (c4) equal to length B. If length B equals Leplus the predefined drill depth of the hole to be applied with the bone milling drill (cl), the bone milling drill (cl) can be slid through the axial circular through hole (e7) of the drill sleeve (el) only over a distance from end (c4) equal to length B and the drill depth of the hole to be applied with the bone milling drill (cl) cannot exceed the predefined drill depth.

[0076] In another preferred embodiment, the bone milling drill (cl) has a line marker in the radial direction at a distance from end (c4) equal to length B, wherein length B equals Leplus the predefined drill depth of the hole to be applied with the bone milling drill (cl). When during drilling the line marker coincides with end (e7) of drill sleeve (el), the predefined drill depth is reached and drilling should be stopped.

[0077] Exemplary embodiments of the bone milling drill (cl) are presented in Figures 3 A and 3B. Sizer-positioner (dl )

[0078] In a preferred embodiment, the surgical kit of parts according to the first aspect further comprises a sizer-positioner (dl) having a length Ld in the axial direction, said sizer-positioner (dl) comprising a base plate structure (d2) having a first concave surface (d2a), i.e. curved inward, and a second surface (d2b), preferably a second convex surface (d2b), and at least one centralized circular through hole (d3) and further comprising a hollow cylinder (d4) with an axial hole (d5) having a circular geometry in the radial direction over the whole length. The sizer-positioner (dl) has two ends (d6,dl0) in the axial direction. The hollow cylinder (d4) is at one end (d6) perpendicularly fixed to the second surface (d2b) of base plate structure (d2) such that the axial hole (d5) of the hollow cylinder (d4) and the centralized circular through hole (d3) of the base plate structure (d2) together form an axial circular through hole (d7) over the whole length Ld with an internal diameter Dd, internal-

[0079] This sizer-positioner (dl) can be advantageously used to place the guide wire (al) at the correct place of the (osteo)chondral defect and with the right orientation as compared to the articular surface of the defect before and during forcing the drill tip (a2) of the guide wire (al) into the cartilage and into the underlying bone. In such embodiments, the length Ld is smaller than Labecause the guide wire (al) should be forced a certain depth into the bone and the guide wire (al) should protrude from the sizer-positioner (dl) to be able to force the guide wire (al) into the bone. More in particular, in such embodiments, the length Ld of the sizer-positioner (dl) should preferably be smaller than Laminus the intended drill depth of the guide wire (al).

[0080] Internal diameter Dd, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial circular through hole (d7) of the sizer-positioner (dl). As will be appreciated by those skilled in the art, the wording ‘Dd, internal substantially equals Da, external in conjunction with ‘such that the guide wire (al) can be slid through the axial circular through hole (d7) of the sizer-positioner (dl)’ means that the internal diameter Dd, internal is as similar to Da, external as possible with the proviso that the guide wire (al) can be slid through the axial circular through hole (d7) of the sizer-positioner (dl) without too much friction. On the other hand, it means that the internal diameter Dd, internal is close enough to Da, external to avoid wiggling of the guide wire (al) in sizer-positioner (dl).

[0081] As indicated hereinbefore, the base plate structure (d2) is to be positioned onto the (osteo)chondral defect, i.e. onto the articular surface, preferably with the centralized circular through hole (d3) on the middle of the defect. This guarantees that the guide wire (al) is positioned in the middle of the defect. The articular surfaces of the knee joint are typically more or less convex shaped (curved outward). In order to be able to place the base plate structure (d2) onto the articular surface wherein the hollow cylinder (d4) has a more or less perpendicular orientation to the articular surface, the first surface (d2a) of the base plate structure (d2) is concave (curved inward).

[0082] In a preferred embodiment, the base plate structure (d2) has a circular form in the radial direction with a diameter of between 5 and 35 mm.

[0083] In a preferred embodiment, the base plate structure (d2) has two or more decentralized through holes (d8) in the axial direction. Using the two or more decentralized through holes (d8), one can easily see whether the centralized circular through hole (d3) is positioned onto the middle of the (osteo)chondral defect.

[0084] In another preferred embodiment, the base plate structure (d2) has two or more decentralized through holes (d8) and two or more concentric circles (d9) indicated on the second surface (d2b), said two or more decentralized through holes (d8) being interrupted by the two or more concentric circles (d9). With these two or more concentric circles (d9), one can easily see how big the defect is and how big the diameter of the implant and the hole to be drilled must be to repair the defect.

[0085] The external diameter Dd, external of the hollow tube (d4) is not particularly limited. The external diameter Dd, external can vary in the axial direction and can have a non-circular cross section in the radial direction, for example a cross section that provides better grip. In preferred embodiments, the external diameter Dd, external is smaller than the diameter of the base plate structure (d2) in the radial direction.

[0086] Exemplary embodiments of the sizer-positioner (dl) are presented in Figures 4A to 4C.

[0087] Drill sleeve ( el )

[0088] In a preferred embodiment, the surgical kit of parts according to the first aspect further comprises a drill sleeve (el) having a length Lein the axial direction, said drill sleeve (el) comprising a base plate structure (e2) having a first concave surface (e2a) and a second surface (e2b), preferably a second convex surface (e2b), with at least one centralized circular through hole (e3) and further comprising a hollow cylinder (e4) with an axial hole (e5) having a circular geometry in the radial direction over the whole length. The drill sleeve (el) has two ends (e6,e7) in the axial direction. The hollow cylinder (e4) is at one end (e6) perpendicularly fixed onto the second surface (e2b) of the base plate structure (e2) such that the axial hole (e5) of the hollow cylinder (e4) and the centralized circular through hole (e3) of the base plate structure (e2) together form an axial circular through hole (e8) over the whole length Lewith an internal diameter De, internal.

[0089] Internal diameter De, internal substantially equals Dc, external such that the bone milling drill (cl) can be slid through the axial circular through hole (e8) of the drill sleeve (el). As will be appreciated by those skilled in the art, the wording ‘De, internal substantially equals Dc, external in conjunction with "such that the bone milling drill (cl) can be slid through the axial circular through hole (e8) of the drill sleeve (elf means that the internal diameter De, internal is as similar to Dc, external as possible with the proviso that the bone milling drill (cl) can be slid through the axial circular through hole (e8) of the drill sleeve (el) without too much friction. On the other hand, it means that the internal diameter De, internal is close enough to Dc, external to avoid wiggling of the bone milling drill (cl) in drill sleeve (el).

[0090] In a preferred embodiment, the base plate structure (e2) has a circular form in the radial direction with a diameter of between 5 and 35 mm.

[0091] The external diameter De, external of the hollow tube (e4) is not particularly limited. The external diameter De, external can vary in the axial direction and can have a non-circular cross section in the radial direction, for example a cross section that provides better grip. In preferred embodiments, the external diameter De, external is smaller than the diameter of the base plate structure (e2) in the radial direction.

[0092] As described hereinbefore, the drill sleeve (el) can be advantageously used to limit the drill depth of the hole to be applied with the bone milling drill (cl) to a predefined value, for example if the depth the bone milling drill (cl) can be forced into the bone is physically limited by the drill sleeve (el). Moreover, the drill sleeve (el) provides additional stability during drilling.

[0093] In embodiments, the drill sleeve (el) is to be slid over the guide wire (al) with its base plate structure (a2) directed to the articular surface with the (osteo)chondral defect and subsequently the bone milling drill (cl) is slid over the guide wire (al) and into the axial circular through hole (e7) of the drill sleeve (el). Accordingly, the base plate structure (e2) is to be positioned onto the articular surface. The articular surfaces of the knee joint are typically more or less convex shaped (curved outward). In order to be able to place the base plate structure (e2) onto the articular surface wherein the hollow cylinder (e4) has a more or less perpendicular orientation to the articular surface, the first surface (e2a) of the base plate structure (e2) is concave (curved inward).

[0094] As defined in the context of the bone milling drill (cl), the length Leof the drill sleeve (el) typically depends on the geometry of the bone milling drill (cl). Given a specific geometry of the bone milling drill (cl), the kit of parts according to the first aspect can contain more than one drill sleeves (el) of different lengths Leto enable different drilling depths for different implants.

[0095] Exemplary embodiments of the drill sleeve (el) are presented in Figures 5A to 5C.

[0096] Trial insert ( fl )

[0097] In a preferred embodiment, the surgical kit of parts according to the first aspect further comprises a trial insert (fl) being a hollow cylinder (f2) with a length Lf in the axial direction, said hollow cylinder (f2) having an axial hole (f3) with a circular geometry in the radial direction over the whole length and an internal diameter Df, internal. The hollow cylinder (f2) has at least two different zones (f4a,f4b) in the axial direction having different external diameters in the radial direction. The hollow cylinder (f2) has two ends (f5, f6) in the axial direction.

[0098] One zone (f4a) at one end (f5) of the hollow cylinder (f2) in the axial direction has a length Lf4a, a circular geometry in the radial direction and an external diameter Df4a, external, and one zone (f4b) adjacent to zone (f4a) has a length Lf4b and an external diameter Df4b, external that is smaller than Df4a, external, with the proviso that Df4a, external substantially equals Dc, external. Accordingly, Df4a, external also substantially equals Db, external. In a preferred embodiment, the wording ‘ Df4a, external Substantially equals Dc, external and Db, external means that Df4a, external equals Dc, external minus between 0.05 and 0.15 mm and Db, external minus between 0.05 and 0.15 mm, such as Dc, external - 0.1 mm and Db, external - 0.1 mm.

[0099] Internal diameter Df, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (f3) of the trial insert (fl). The length Lf4a of the first zone (f4a) equals the intended drill depth of the hole to be applied with the bone milling drill (cl). In a preferred embodiment, length Lf4a of zone (f4a) of trial insert (fl) is between 7 and 40 mm, such as between 8.5 and 10.5 mm or between 20.5 and 30.5 mm.

[0100] Since zone (f4b) adjacent to zone (f4a) has an external diameter Df4b, external that is smaller than Df4a, external, ‘trial’ insertion of the zone (f4a) into the hole drilled with the bone milling drill (cl) immediately reveals whether the hole meets the required dimensions for inserting the implant.

[0101] As described hereinbefore, the hollow cylinder (f2) has at least two different zones (f4a,f4b). The hollow cylinder (f2) can also have three, four or five zones, wherein the external diameter varies in the axial direction. In an embodiment, the hollow cylinder (f2) has three different zones (f4a,f4b,f4c) in the axial direction having different external diameters, wherein (f4a) and (f4b) are as defined hereinbefore and wherein zone (f4c) is adjacent to zone (f4b), has an external diameter Df4c, external that is greater than Df4b, external and extends over a length Lf4c to end (f6). Df4c, external and / or Lf4c are typically different from Df4a, external and Lf4, such that both zones (f4a) and (f4c) can be used for ‘trial’ insertion in holes of different sizes to check whether the holes meet the required dimensions for inserting the implant.

[0102] In another embodiment, the hollow cylinder (f2) has at least five different zones (f4a,f4b, f4c,f4d,f4e) in the axial direction wherein adjacent zones have different external diameters. See in this respect for example Figure 6b, wherein zones (f4a) and (f4c), having the same external diameter in the radial direction but different lengths in the axial direction, can be used for ‘trial’ insertion in holes of different depths, and zone (f4e) can for example be used as handgrip.

[0103] As will be appreciated by those skilled in the art, the geometry of the trial insert (fl) depends on the size of the implant that is to be inserted and thus also on the hole that is drilled using the bone milling drill (cl). Given a specific geometry of the bone milling drill (cl) or implant to be inserted, the kit of parts according to the first aspect can contain one or more different trial inserts (fl).

[0104] Exemplary embodiments of the trial insert (fl) are presented in Figures 6 A to 6C.

[0105] Method of repairins an (osteo)chondral defect of the knee

[0106] In a second aspect, the invention concerns a method of repairing an (osteo)chondral defect of the knee in a subject with the surgical kit of parts according to the first aspect, said method comprising the steps of:

[0107] (i) exposing the cartilage of the articular surface of the knee joint of the subject, said knee joint having an (osteo)chondral defect;

[0108] (ii) forcing the drill bit tip (a2) of the guide wire (al) into the cartilage and into the underlying bone, such that the guide wire (al) is fixed substantially perpendicularly to the articular surface;

[0109] (iii) sliding the cartilage punch (bl) over the guide wire (al) with its circular cutting edge (b5) directed towards the defect and forcing the circular cutting edge (b5) into the cartilage, preferably through the cartilage until the underlying bone is reached, to form a sharp-edged cylindrical cut in the cartilage, preferably through the cartilage;

[0110] (iv) removing the cartilage punch (bl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;

[0111] (v) sliding the bone milling drill (cl) over the guide wire (al);

[0112] (vi) drilling a cylindrical hole into the cartilage and into the underlying bone with the bone milling drill (cl), wherein the hole has a diameter Dc, external and a depth E; (vii) removing the bone milling drill (cl);

[0113] (viii) removing the guide wire (al); and

[0114] (ix) positioning a cylindrical implant (gl) having a length equal to depth E minus between 0.3 and 0.7 mm and having a circular cross section and an external diameter of Dc, external + between 0.05 and 0.20 mm in the radial direction, into the hole obtained in step (viii).

[0115] In a preferred embodiment, the subject is a mammal. In an even more preferred embodiment, the subject is a human being or a horse.

[0116] Step (i) of exposing the cartilage of the articular surface of the knee joint of the subject involves making an opening in the weak tissue of the knee to make the articular surface accessible.

[0117] Since both the cartilage punch (bl) and the bone milling drill (cl) slide over the guide wire (al) in steps (iii) and (v), respectively, and since the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5), the end milling cutter (c5) creates a hole in step (v) that is perfectly within the contour of the sharp-edged cylindrical cut prepared in step (iii) in the cartilage by the cartilage punch (bl). Accordingly, no frayed cartilage around the hole opening is observed.

[0118] In step (ii), the drill bit tip (a2) of the guide wire (al) is preferably forced into the cartilage and into the underlying bone over a depth of between 20 and 50 mm, more preferably a depth of between 30 and 40 mm. Forcing the drill bit tip (a2) of the guide wire (al) into the cartilage and into the underlying bone is preferably performed using drilling.

[0119] The cylindrical implants (gl) preferably have a length of between 7 and 40 mm in the axial direction, such as a length between 8 and 10 mm or between 20 and 30 mm.

[0120] The use of a cylindrical implant (gl) having an external diameter that is slightly larger than the diameter Dc, external of the hole provided in the bone assures a tight fit between bone and implant (gl). In a preferred embodiment, the cylindrical implant (gl) has an external diameter of Dc, external + between 0.08 and 0.15 mm

[0121] In step (ix), a cylindrical implant (gl) having a length equal to depth E minus between 0.3 and 0.7 mm is positioned into the hole obtained in step (viii). The inventors have found that using an implant (gl) that has a slightly lower length than the depth E of the hole facilitates growth of cartilage on the implant to form a smooth surface with the surrounding articular cartilage and further reduces the formation of kissing lesions on contacting of articular cartilage covering opposing bone ends.

[0122] In a preferred embodiment, a cylindrical implant (gl) having a length equal to depth E minus between 0.4 and 0.6 mm, such as a length equal to depth E minus about 0.5 mm, is positioned in step (ix) into the hole obtained in step (viii).

[0123] In a preferred embodiment, the cylindrical implant (gl) comprises polyetherketoneketone (PEKK), poly(carbonate-urethane)urea (PCUU) and optionally a tantalum-based contrast agent.

[0124] In a preferred embodiment, the method applies a surgical kit of parts according to the first aspect further comprising the sizer-positioner (dl), drill sleeve (el) and optionally the trial insert (fl). Accordingly, in a preferred embodiment, the method according to the second aspect comprises the following order of steps:

[0125] (i) exposing the cartilage of the articular surface of the knee joint of the subject, said knee joint having an (osteo)chondral defect;

[0126] (iia) providing a sizer-positioner (d 1 ) as defined hereinbefore and positioning the first concave surface (d2a) of base plate structure (d2) onto the defect, wherein the centralized circular through hole (d3) is preferably positioned onto the middle of the defect and applying the guide wire (al) into the axial circular through hole (d7) of the sizer-positioner (dl);

[0127] (ii) forcing the drill bit tip (a2) of the guide wire (al) into the cartilage and into the underlying bone, such that the guide wire (al) is fixed substantially perpendicularly to the articular surface;

[0128] (iib) removing the sizer-positioner (dl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;

[0129] (iii) sliding the cartilage punch (bl) over the guide wire (al) with its circular cutting edge (b5) directed towards the defect and forcing the circular cutting edge (b5) into the cartilage, preferably through the cartilage until the underlying bone is reached, to form a sharp-edged cylindrical cut in the cartilage, preferably through the cartilage;

[0130] (iv) removing the cartilage punch (bl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;

[0131] (va) providing a drill sleeve (el) as defined hereinbefore and sliding the drill sleeve (el) over the guide wire (al) with the first concave surface (e2a) of its base plate structure (e2) directed to the defect; (v) sliding the bone milling drill (cl) over the guide wire (al) and into the axial circular through hole (e7) of the drill sleeve (el);

[0132] (vi) drilling a cylindrical hole into the cartilage and into the underlying bone with the bone milling drill (cl), wherein the hole has a diameter Dc, external and a depth E;

[0133] (vii) removing the bone milling drill (cl) and the drill sleeve (el);

[0134] (viii) removing the guide wire (al); and

[0135] (ix) positioning a cylindrical implant (gl) having a length equal to depth E minus between 0.3 and 0.7 mm and having a circular cross section and an external diameter of Dc, external + between 0.05 and 0.20 mm in the radial direction, into the hole obtained in step (viii).

[0136] In a preferred embodiment, the method further comprises the step of inserting a trial insert (fl) as defined hereinbefore into the hole between steps (vii) and (viii) and checking whether the diameter and depth of the hole meets predetermined requirements.

[0137] If, upon checking, the depth of the hole appears to be too big, the hole can be partially filled with bone debris obtained and collected in step (vi) before positioning the cylindrical implant (gl).

[0138] If, upon checking, the diameter of the hole appears to be too big, steps (iii) and further can be repeated with a cartilage punch (bl), bone milling drill (cl) and optionally a drill sleeve (el) with increased diameters.

[0139] If, upon checking, the diameter of the hole appears to be too small, drilling step (vi) can be repeated.

[0140] If, upon checking, the depth of the hole appears to be too small, drilling step (vi) can be repeated, optionally with a drill sleeve having a smaller length Le.

[0141] Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art.

[0142] Furthermore, for a proper understanding of this document and its claims, it is to be understood that the verb ‘to comprise" and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article ‘a" or ‘an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article ‘a" or ‘an" thus usually means ‘at least one" . EXAMPLES

[0143] Example 1

[0144] The method according to the invention was applied on human cadaveric knees having (osteo)chondral defects using the guide wire (al), cartilage punch (bl), milling drill (cl), sizerpositioner (dl), drill sleeve (el), trial insert (fl) and cylindrical implant (gl) as defined herein.

[0145] As cylindrical implants (gl), bi-layered non-biodegradable implants (‘JS001 plug)’ provided by JointSphere B.V. (’s-Hertogenbosch, the Netherlands) were applied.

[0146] By directing the circular cutting edge of the cartilage punch (bl) towards the (osteo)chondral defect of the knee and forcing the circular cutting edge into the cartilage until the underlying bone was reached, a sharp-edged cylindrical cut, i.e. without frayed edges, was formed through the cartilage. Subsequent careful application of the bone milling drill within the contour of the sharp-edged cylindrical cut provided a drill hole for implantation without producing a frayed cartilage edge around the hole opening. The implant (gl) could be easily inserted.

[0147] Comparative Example 1

[0148] In a comparative experiment, the method of Example 1 was repeated without the use of the cartilage punch (bl). Drilling through the layer of articular cartilage resulted in a frayed edge where the drill bit cut the cartilage. In other words, drilling at the place of the (osteo)chondral defect resulted in additional damage to the cartilage, which complicated the insertion of the implant (gl) and which will adversely affect the subsequent healing process.

Claims

CLAIMS1. Surgical kit of parts comprising the following instruments:• a guide wire (al) having a drill tip (a2), a circular cross section and an external diameter Da, external in the radial direction and a length Lain the axial direction;• a cartilage punch (bl), being a hollow cylinder (b2) with a length Lb in the axial direction, said hollow cylinder (b2) having an axial hole (b3) with a circular geometry in the radial direction over the whole length, wherein the hollow cylinder (b2) forms at one end (b4) a circular cutting edge (b5) with an inwardly tapered circular cutting wall (b6), wherein said circular cutting edge (b5) has an external diameter Db, external in the radial direction and wherein the axial hole (b3) has an internal diameter Db.internal, with the proviso that Db, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (b3) of the cartilage punch (bl); and• a bone milling drill (cl) being a hollow cylinder (c2) with a length Lcin the axial direction, wherein the hollow cylinder (c2) has an axial hole (c3) having a circular geometry in the radial direction over the whole length with a diameter Dc, internal, wherein one end (c4) of the hollow cylinder (c2) has the form of an end milling cutter (c5) with an external diameter Dc, external, with the proviso that Dc, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial hole (c3) of the bone milling drill (cl) and with the further proviso that the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) equals the external diameter Dc, external of the end milling cutter (c5) of the bone milling drill (cl).

2. Surgical kit of parts according to claim 1, further comprising a sizer-positioner (dl) having a length Ld in the axial direction, said sizer-positioner (dl) comprising a base plate structure (d2) having a first concave surface (d2a) and a second surface (d2b) and at least one centralized circular through hole (d3) and further comprising a hollow cylinder (d4) with an axial hole (d5) having a circular geometry in the radial direction over the whole length, wherein the hollow cylinder (d4) is at one end (d6) perpendicularly fixed to the second surface (d2b) of base plate structure (d2) such that the axial hole (d5) of the hollow cylinder (d4) and the centralized circular through hole (d3) of the base platestructure (d2) together form an axial circular through hole (d7) over the whole length Ld with an internal diameter Dd, internal, with the proviso that Dd, internal substantially equals Da, external, such that the guide wire (al) can be slid through the axial circular through hole (d7) of the sizer-positioner (dl).

3. Surgical kit of parts according to claim 1 or 2, further comprising a drill sleeve (el) having a length Lein the axial direction, said drill sleeve (el) comprising a base plate structure (e2) having a first concave surface (e2a) and a second surface (e2b), with at least one centralized circular through hole (e3) and further comprising a hollow cylinder (e4) with an axial hole (e5) having a circular geometry in the radial direction over the whole length, wherein the hollow cylinder (e4) is at one end (e6) perpendicularly fixed onto the second surface (e2b) of the base plate structure (e2) such that the axial hole (e5) of the hollow cylinder (e4) and the centralized circular through hole (e3) of the base plate structure (e2) together form an axial circular through hole (e8) over the whole length Lewith an internal diameter De, internal, with the proviso that De, internal equals Dc, external such that the bone milling drill (cl) can be slid through the axial circular through hole (e8) of the drill sleeve (el).

4. Surgical kit of parts according to any one of claims 1 to 3, further comprising a trial insert (fl) being a hollow cylinder (f2) with a length Lf in the axial direction, said hollow cylinder (f2) having an axial hole (f3) with a circular geometry in the radial direction over the whole length and an internal diameter Df, internal, wherein the hollow cylinder (f2) has at least two different zones (f4a,f4b) in the axial direction having different external diameters in the radial direction, wherein one zone (f4a) at one end (f5) of the hollow cylinder (f2) in the axial direction has a length Lf4a, a circular geometry in the radial direction and an external diameter Df4a, external, and one zone (f4b) adjacent to zone (f4a) has a length Lf4b and an external diameter Df4b, external that is smaller than Df4a, external, with the proviso that Df4a, external substantially equals Dc, external and with the further proviso that that Df, internal equals Da, external, such that the guide wire (al) can be slid through the axial hole (f3) of the trial insert (fl).

5. Surgical kit of parts according to claim 4, wherein Df4a, external equals Dc, external minus between 0.05 and 0.15 mm.

6. Surgical kit of parts according to claim 4 or 5, wherein length Lf4a of zone (f4a) of trial insert (fl) is between 7 and 40 mm.

7. Surgical kit of parts according to claim 3, wherein the bone milling drill (cl) has a zone (c6) wherein the external diameter exceeds the internal diameter De, internal of the drill sleeve (el) over a length C starting from a distance from end (c4) equal to length B, such that the bone milling drill (cl) can be slid through the axial circular through hole (e7) of the drill sleeve (el) only over a distance from end (c4) equal to length B.

8. Surgical kit of parts according to any one of claims 1 to 7, wherein the external diameter Da, external of the guide wire (al) is between 1.5 and 3.5 mm.

9. Surgical kit of parts according to any one of claims 1 to 8, wherein the external diameter De, external of the end milling cutter (c5) of the bone milling drill (cl) and the external diameter Db, external of the circular cutting edge (b5) of the cartilage punch (bl) are between 5 and 25 mm.

10. Surgical kit of parts according to any one of claims 1 to 9, wherein the cartilage punch (bl) contains a first part (b8) containing the circular cutting edge (b5) with the inwardly tapered circular cutting wall (b6) and a second part (b9) that is a shaft and that is attached to the first part (b8) and can be detached from the first part (b8).

11. Surgical kit of parts according to any of claim 1 to 10, wherein the instruments (al) to (fl) are made of metal, preferably of stainless steel.

12. Surgical kit of parts according to claim 2, wherein the base plate structure (d2) has a circular form in the radial direction with a diameter of between 5 and 35 mm.

13. Surgical kit of parts according to claim 2 or 12, wherein the base plate structure (d2) has two or more decentralized through holes (d8) and preferably two or more concentric circles (d9) indicated on the second surface (d2b), said two or more decentralized through holes (d8) being interrupted by the two or more concentric circles (d9).

14. Method of repairing an (osteo)chondral defect of the knee in a subject with the surgical kit of parts according to claim 1, said method comprising the steps of:(i) exposing the cartilage of the articular surface of the knee joint of the subject, said knee joint having an (osteo)chondral defect;(ii) forcing the drill bit tip (a2) of the guide wire (al) into the cartilage and into the underlying bone, such that the guide wire (al) is fixed substantially perpendicularly to the articular surface;(iii) sliding the cartilage punch (bl) over the guide wire (al) with its circular cutting edge (b5) directed towards the defect and forcing the circular cutting edge (b5) into the cartilage, preferably through the cartilage until the underlying bone is reached, to form a sharp-edged cylindrical cut in the cartilage, preferably through the cartilage;(iv) removing the cartilage punch (bl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;(v) sliding the bone milling drill (cl) over the guide wire (al);(vi) drilling a cylindrical hole into the cartilage and into the underlying bone with the bone milling drill (cl), wherein the hole has a diameter Dc, external and a depth E;(vii) removing the bone milling drill (cl);(viii) removing the guide wire (al); and(ix) positioning a cylindrical implant (gl) having a length equal to depth E minus between 0.3 and 0.7 mm and having a circular cross section and an external diameter of Dc, external + between 0.05 and 0.20 mm in the radial direction, into the hole obtained in step (viii).

15. Method of repairing an (osteo)chondral defect of the knee in a subject according to claim 14, said method comprising the following order of steps:(i) exposing the cartilage of the articular surface of the knee joint of the subject, said knee joint having an (osteo)chondral defect;(iia) providing a sizer-positioner (dl) as defined in claim 2 and positioning the first concave surface (d2a) of base plate structure (d2) onto the defect, wherein the centralized circular through hole (d3) is preferably positioned onto the middle of the defect and applying the guide wire (al) into the axial circular through hole (d7) of the sizer-positioner (dl);(ii) forcing the drill bit tip (a2) of the guide wire (al) into the cartilage and into the underlying bone, such that the guide wire (al) is fixed substantially perpendicularly to the articular surface;(iib) removing the sizer-positioner (dl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;(iii) sliding the cartilage punch (bl) over the guide wire (al) with its circular cutting edge (b5) directed towards the defect and forcing the circular cutting edge (b5) into the cartilage, preferably through the cartilage until the underlying bone is reached, to form a sharp-edged cylindrical cut in the cartilage, preferably through the cartilage;(iv) removing the cartilage punch (bl), wherein the guide wire (al) remains fixed in the cartilage and in the underlying bone;(va) providing a drill sleeve (el) as defined in claim 3 and sliding the drill sleeve (el) over the guide wire (al) with the first concave surface (e2a) of its base plate structure (e2) directed to the defect;(v) sliding the bone milling drill (cl) over the guide wire (al) and into the axial circular through hole (e7) of the drill sleeve (el);(vi) drilling a cylindrical hole into the cartilage and into the underlying bone with the bone milling drill (cl), wherein the hole has a diameter Dc, external and a depth E;(vii) removing the bone milling drill (cl) and the drill sleeve (el);(viii) removing the guide wire (al); and(ix) positioning a cylindrical implant (gl) having a length equal to depth E minus between 0.3 and 0.7 mm and having a circular cross section and an external diameter of Dc, external + between 0.05 and 0.20 mm in the radial direction, into the hole obtained in step (viii).

16. Method according to claim 15, wherein the bone milling drill (cl) has a zone (c6) wherein the external diameter exceeds the internal diameter De, internal of the drill sleeve (el) over a length C starting from a distance from end (c4) equal to length B, such that the bone milling drill (cl) can be slid through the axial circular through hole (e7) of the drill sleeve (el) only over a distance from end (c4) equal to length B, wherein length B equals the length Leof the drill sleeve (el) plus the depth E of the hole to be applied with the bone milling drill (cl), such that the depth of the hole applied with the bone milling drill (cl) in step (vi) cannot exceed depth E.

17. Method according to claim 15 or 16, further comprising the step of inserting a trial insert (fl) as defined in claim 4 into the hole between steps (vii) and (viii) and checking whether the diameter and depth of the hole meet predetermined requirements.

18. Method according to any one of claims 14 to 17, wherein the cylindrical implants (gl) have a length of between 7 and 40 mm in the axial direction.

19. Method according to any one of claims 14 to 18, wherein the cylindrical implant (gl) comprises polyetherketoneketone (PEKK), poly(carbonate-urethane)urea (PCUU) and optionally a tantalum-based contrast agent.

20. Method according to any one of claims 14 to 19, wherein the subject is a human being or a horse.

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