SURGICAL INSTRUMENT SYSTEM

Description

[0001] The invention relates to a surgical instrument system according to the preamble of claim 1.

[0002] The use of orthopedic prostheses as artificial replacements for a patient's damaged or worn-out natural bone structures is common medical practice. Hip and knee replacement surgeries, in particular, are now part of the standard repertoire of surgical orthopedics.

[0003] In total knee arthroplasty (TKA), worn or otherwise impaired joint surfaces of the femur and / or tibia due to disease or accident are replaced with a knee joint prosthesis. Such knee joint prostheses typically comprise a femoral component, which is implanted at the distal end of the femur, and a tibial component, which is implanted at the proximal end of the tibia. To ensure proper function of the artificial joint replacement, the said components must be positioned as precisely as possible in terms of their position and orientation in relation to the patient's anatomy and their body axes. Otherwise, an unsatisfactory result for the patient is to be expected. There are different surgical approaches regarding the positioning of the components.

[0004] A previously common approach known as mechanical alignment involves aligning the position and alignment of the artificial joint axes of the knee joint prosthesis to a mechanically ideal level, without taking into account any orthopedic deformities of the patient. The longitudinal axis of the tibia often serves as the reference axis for alignment and positioning. Clinical studies have shown that the mechanical alignment approach can lead to a perceived unnatural function of the artificial knee joint.

[0005] Another approach is known as kinematic alignment. In this procedure, the femoral and tibial components are positioned taking into account any orthopedic misalignments of the patient. The goal is to restore the patient's natural joint alignment, which may be subject to misalignment. Clinical studies have shown that the kinematic alignment approach is often associated with improved patient satisfaction. In particular, patients perceive the function of the artificial knee joint as more natural.

[0006] The aim of further improving patient satisfaction is accompanied by a fundamental need for surgical instruments and instrument systems that are as precise, easy to use and cost-effective as possible for the implementation of kinematic alignment.

[0007] The present invention relates to such surgical instrument systems, in particular to a surgical instrument system for positioning a distal femoral cutting block in the context of kinematic alignment.

[0008] Such a surgical instrument system is known from US 10,130,375 B2 and comprises an intramedullary rod and a reference block. The intramedullary rod is elongated between a proximal rod end and a distal rod end and is designed for insertion into the medullary cavity of a femur. The reference block has a proximally oriented block rear side, which is designed to engage the distal condyles of the femur. Furthermore, the reference block has a fixation device for releasably securing a distal femoral cutting block. For femoral positioning, the reference block can be pushed onto the intramedullary rod in a proximal direction, starting from the distal rod end. For this purpose, the reference block of the known surgical instrument system has an elongated hole. The elongated hole extends axially between the block rear side and a distally opposite block front side and is elongated mediolaterally.This allows the reference block to have limited relative mobility mediolaterally when pushed in place. Furthermore, the reference block can tilt relative to the intramedullary rod about an anteroposteriorly oriented tilt axis. The position of the tilt axis relative to the intramedullary rod inserted in the elongated hole is not clearly defined and can vary within fixed limits.

[0009] From DE 696 36 636 T2, DE 697 22 052 T2 and DE 10 2015 100049 A1 a surgical instrument system with the generic features of claim 1 is known.

[0010] The object of the invention is to provide a surgical instrument system of the type mentioned above, which enables precise adjustment of the position and orientation of the reference block and ultimately improved surgical results.

[0011] This object is achieved by providing a surgical instrument system having the features of claim 1. The solution according to the invention achieves improved mounting of the reference block on the intramedullary rod. Compared to solutions known from the prior art, the invention enables kinematically well-defined relative mobility of the reference block. This allows the position and orientation of the reference block to be precisely adjusted. In particular, the pivoting mobility of the reference block about the anteroposteriorly oriented pivot axis allows the so-called varus-valgus angle to be precisely adjusted. This prevents misalignments of the kinematic axes of the knee joint replacement and ultimately enables improved surgical results. The reference block is mounted or can be mounted indirectly, namely by means of the bearing element, on the intramedullary rod.For this purpose, the bearing element has the aforementioned receiving bore. The dimensions of the receiving bore are complementary to those of the intramedullary rod. When the reference block is pushed on, the receiving bore and the intramedullary rod are coaxially aligned with one another, and the intramedullary rod is received radially in the receiving bore with a positive fit. As a result of the positive fit, the bearing element and the intramedullary rod are fixed relative to one another mediolaterally and anteroposteriorly. The aforementioned pivoting mobility of the reference block in relation to the intramedullary rod is made possible by the pivoting mounting of the bearing element on the reference block. The mounting can be designed, for example, as a sliding guide, axial guide, or the like and can comprise components and / or sections that are arranged and / or formed on the one hand on the reference block and on the other hand on the bearing element.

[0012] The position and direction terms used in this description refer to the patient's body, in particular their femur, and are to be understood according to their usual anatomical meaning. Consequently, "anterior" means front or in front, "posterior" means back or behind, "medial" means inner or inside, "lateral" means outer or outside, "proximal" means toward the body's center, and "distal" means away from the body's center. Furthermore, "proximodistal" means along, preferably parallel to, a proximal-distal axis, "anteroposterior" means along, preferably parallel to, an anterior-posterior axis, and "mediolateral" means along, preferably parallel to, a medial-lateral axis. These axes are orthogonal to each other and can, of course, be set in relation to X, Y, and Z axes unrelated to the patient's anatomy.For example, the proximal-distal axis can alternatively be referred to as the X-axis. The medial-lateral axis can be referred to as the Y-axis. The anterior-posterior axis can be referred to as the Z-axis. For improved illustration and simplicity of naming, the aforementioned anatomical position and direction terms will be used primarily below. Furthermore, terms such as "back" of a component or section of the surgical instrument system, for example, the reference block, are used with reference to a proximally directed viewing direction. Conversely, terms such as "front" are used with reference to a distally directed viewing direction.

[0013] In an embodiment of the invention, the reference block has a sliding guide with mediolaterally opposing, concavely curved guide surfaces in the shape of a circular arc, and the bearing element has mediolaterally opposing, convexly curved sliding surfaces in the shape of a circular arc. The sliding surfaces and the pivot axis interact with the guide surfaces in a rotationally sliding manner and in a form-fitting manner in the proximodistal and mediolateral translational directions. This achieves a structurally particularly simple yet precise and robust pivotable mounting between the bearing element and the reference block. The guide surfaces and the sliding surfaces are each circularly arc-shaped with respect to an anterior or posterior viewing direction. The guide surfaces and the sliding surfaces are complementarily curved to one another, with the guide surfaces being concave and the sliding surfaces each being convex. The guide surfaces define an inner diameter of the sliding guide.The sliding surfaces define a complementary outer diameter. The outer diameter is fitted into the inner diameter. The fit is preferably selected such that precise, play-free, and at the same time sufficiently smooth relative mobility is achieved between the bearing element and the reference block. The receiving bore is preferably arranged in the mediolateral direction, preferably centrally, between the opposing sliding surfaces of the bearing element. The opposing guide surfaces can also be referred to as the first guide surface and second guide surface, or alternatively as the medial guide surface and lateral guide surface. The same applies mutatis mutandis to the sliding surfaces.

[0014] In a further embodiment of the invention, the guide surfaces each extend straight longitudinally parallel to the pivot axis, with the sliding surfaces interacting with the guide surfaces in a translationally movable manner along the pivot axis. This allows the reference block to slide anteroposteriorly relative to the intramedullary rod. This allows adjustment of the anteroposterior position of the reference block. This improves the adaptability of the positioning of the reference block to a given femur size. Due to their straight longitudinal extension, the opposing guide surfaces each form a guide track. The reference block is translationally displaceable relative to the bearing element along the pivot axis and / or the guide track between an upper end position and a lower end position.

[0015] In a further embodiment of the invention, the reference block has a receiving slot extending from the rear of the block to a distally opposite front of the block and extending straight and elongated parallel to the pivot axis, with mediolaterally opposite inner walls on which the guide surfaces are arranged and / or formed, wherein the receiving slot has an insertion opening for inserting the bearing element, arranged anteriorly on a block upper side or posteriorly on a block lower side of the reference block. The receiving slot enables particularly simple and time-saving attachment of the bearing element to the reference block or vice versa. For example, the bearing element can first be pushed onto the distal rod end in the proximal direction with the receiving bore first.The reference block can then be pushed onto the bearing element along the pivot axis anteriorly or posteriorly, depending on whether the insertion opening is arranged on the upper or lower side of the block. Alternatively, the bearing element can be inserted into the receiving slot before being pushed onto the intramedullary rod. In one embodiment, the insertion opening is arranged on the upper side of the reference block. In a further embodiment, the insertion opening is arranged on the lower side of the block. The upper and lower sides of the block are opposite one another anteroposteriorly. Preferably, the receiving slot divides the reference block into a lateral block section and a medial block section. A rear side of the medial block section is configured to bear against the medial distal condyle of the femur. A rear side of the lateral block section is configured to bear against the lateral distal condyle of the femur.

[0016] In a further embodiment of the invention, the reference block has an axle guide with at least one axle element oriented coaxially to the pivot axis, and the bearing element has at least one axle receptacle oriented coaxially to the pivot axis, wherein the axle element engages in the axle receptacle so as to be slidable about the pivot axis. The axle element is preferably designed in the shape of a pin, bolt, and / or journal, so that it can also be referred to as an axle pin, axle bolt, or axle journal. The axle guide has a comparatively simple design. This allows for easy manufacture and assembly, as well as associated cost savings. At the same time, a sufficiently precise pivotable bearing can still be achieved. In one embodiment, the reference block has two axle elements, and the bearing element accordingly has two axle receptacles, each of which interacts with one of the axle elements.In this context, one can also speak of an anterior axle element and a posterior axle element. The same applies mutatis mutandis to the axle mounts. In the aforementioned configuration, the mounting hole is preferably arranged anteroposteriorly, preferably centrally, between the anterior axle mount and the posterior axle mount.

[0017] Furthermore, according to the invention, the at least one bearing element is detachably mounted on the reference block, and there are several different bearing elements with differently inclined longitudinally extending receiving bores, which can be mounted interchangeably on the reference block to adjust a flexion-extension angle of the reference block. The several different bearing elements preferably differ from one another only with regard to the inclination of the receiving bore. Preferably, the different bearing elements are otherwise identical. As a result of the differently inclined longitudinally extending receiving bores, the angle of inclination of the reference block can be adjusted easily and precisely by appropriately selecting the respective bearing element. The receiving bores are inclined at different angles with respect to the proximally oriented rear side of the reference block.The mounting holes are angled differently in the anterior and / or posterior directions relative to the normal direction of the back of the block. This allows for simple and precise adjustment of the flexion-extension angle of the reference block, i.e., its rotation angle around a mediolaterally oriented axis.

[0018] In a further embodiment of the invention, several different compensation elements with different proximodistal thicknesses are provided and can be interchangeably attached to the back of the block to compensate for varying degrees of wear of the posterior condyles. As explained above, the surgical instrument system is intended for implementing the kinematic alignment approach. This approach typically provides dimensional compensation for said condylar wear. For this purpose, the surgical instrument system in this embodiment of the invention has several different and interchangeable compensation elements with different proximodistal thicknesses.

[0019] In a further embodiment of the invention, a cutting block is provided, which is designed to guide cuts on the distal condyles of the femur and is releasably fixed or can be fixed to a fixing device of the reference block. The cutting block can also be referred to as a saw block or cutting jig. The cutting block has at least one guide slot for receiving and guiding a saw blade. The basic design and function of such a cutting block are known to those skilled in the art. The fixing device is preferably arranged in the region of the anterior upper side of the reference block.

[0020] In a further embodiment of the invention, the intramedullary rod has a length between 120 mm and 250 mm, preferably between 150 mm and 220 mm, particularly preferably between 170 mm and 200 mm.

[0021] Further advantages and features of the invention emerge from the claims and from the following description of preferred embodiments of the invention, which are illustrated with reference to the drawings. Fig. 1 shows a schematic perspective view of an embodiment of a surgical instrument system according to the invention with an intramedullary rod, a reference block, a bearing element and a cutting block, Fig. 2 shows a schematic perspective view of the reference block and the bearing element of the surgical instrument system according to Fig. 1 in a direction of view directed towards the back of a block, Fig. 3 in schematic perspective view an intraoperative situation using the surgical instrument system according to Fig. 1 , Fig. 4the surgical instrument system according to Fig. 1 in a schematic side view with a laterally directed view, Fig. 5 a schematic longitudinal section along a section line BB according to Fig. 4 , Fig. 6the surgical instrument system according to the Fig. 1 bis 5 in a schematic plan view with posterior view, Fig. 7 a schematic longitudinal section along a section line AA according to Fig. 6 , Fig. 8 in a schematic perspective view of different bearing elements with differently inclined receiving bores, Fig. 9 in a schematic perspective view of a further embodiment of a surgical instrument system according to the invention in an intraoperative situation, Fig. 10 in a schematic perspective view of the reference block and the bearing element of the surgical instrument system according to Fig. 9 , Fig. 11the surgical instrument system according to Fig. 9 in a schematic plan view with posterior view, Fig. 12 a schematic longitudinal section along a section line AA according to Fig. 11 , Fig. 13the surgical instrument system according to the Fig. 9 bis 12 in a schematic side view with medially directed view and Fig. 14 a schematic longitudinal section along a section line CC according to Fig. 13 .

[0022] According to the Fig. 1 bis 7 A surgical instrument system 1 is provided for use in a knee replacement operation and comprises an intramedullary rod 100, a reference block 200, at least one bearing element 300, a cutting block 400 and at least one compensation element 500.

[0023] The intramedullary rod 100 is straight and elongated between a proximal rod end 101 and a distal rod end 102 and is designed for insertion into a medullary cavity of a femur F (see Fig. 3 ). The intramedullary rod 100 (hereinafter abbreviated to: rod) is aligned coaxially to a proximodistal longitudinal axis of the femur F in the inserted state. In the inserted state, the distal rod end 102 protrudes from the front side of the femur F and projects beyond its distal condyles, whereby Fig. 3 only a lateral distal condyle KL of the femur F is visible.

[0024] The reference block 200 can be pushed onto the rod 100 in the axial direction. The reference block 200 has a block back 201, a block front 202, a block top 203, a block bottom 204, and block outer sides 205, 206. The block back 201 is oriented proximally. This means that an unspecified surface normal of the block back 201 is oriented along a proximodistal axis ( Fig. 1 ), whereby the alignment, as explained in more detail below, does not necessarily have to be parallel. The block front side 202 is distally opposite the block back side 201. The block top side 203 is arranged anteriorly to the reference block 200. The block bottom side 204 is posteriorly opposite the block top side 203. The two block outer sides 205, 206 are mediolaterally opposite each other and can also be referred to as the lateral block outer side 205 and the medial block outer side 206.

[0025] The proximally oriented block back 201 is designed to engage the distal condyles of the femur F (see Fig. 3 ). The reference block 200 is mounted on the distal rod end 102 by means of the bearing element 300.

[0026] For this purpose, the bearing element 300 has a receiving bore 301, which is designed to coaxially and radially form-fittingly receive the distal rod end 102. Furthermore, the bearing element 300 is pivotally mounted on the reference block 200 relative to the reference block 200 at least about an anteroposteriorly oriented pivot axis S.

[0027] The bearing element 300 has a proximally oriented rear side 302, a distally opposite front side 303, an anteriorly oriented upper side 304, a posteriorly opposite lower side 305, and mediolaterally opposite outer sides 306, 307. The latter can also be referred to as lateral outer side 306 and medial outer side 307. The receiving bore 301 is arranged along a longitudinal axis L (see Fig. 8 ) extends longitudinally between the rear side 302 and the front side 303. The longitudinal axis L and the pivot axis S are aligned orthogonally to each other in the bearing element 300. As described in more detail below, different alignments are also provided.

[0028] An unspecified outer circumference of the rod 100 and the receiving bore 301 interact in a form-fitting manner, essentially free of play, in the radial direction of the receiving bore 301. In the axial direction of the receiving bore 301, i.e., along the longitudinal axis L and thus also along the proximodistal axis, the bearing element 300 is slidably movable relative to the rod 100. Furthermore, the bearing element 300 is fundamentally rotatable in the circumferential direction of the rod 100 about the longitudinal axis L. Apart from this, no relative movement whatsoever is possible between the bearing element 300 and the rod 100.

[0029] Due to the pivoting bearing between the reference block 200 and the bearing element 300, the reference block 200 can be positioned at different angular positions about the pivot axis S relative to the rod 100 and thus also to the femur F. This enables simple and precise adjustment of the varus-valgus angle for the subsequent distal resection of the femur F using the cutting block 500.

[0030] The pivot axis S intersects the longitudinal axis L of the receiving bore 301 and thus also the longitudinal axis of the rod 100, which is not separately designated.

[0031] In the embodiment according to the Fig. 1 bis 7 For the purpose of pivoting mounting, a sliding guide with guide surfaces 207, 208 and sliding surfaces 308, 309 is provided (see in particular Fig. 5 ).

[0032] In this case, the reference block 200 has the guide surfaces 207, 208. The bearing element, in contrast, has the sliding surfaces 308, 309.

[0033] The guide surfaces 207, 208 are located mediolaterally opposite each other and are each - with respect to an anterior or posterior viewing direction (see Fig. 5 ) - concavely curved in a circular arc. The sliding surfaces 308, 309 are shaped complementarily to the guide surfaces 207, 208. Accordingly, the sliding surfaces 308, 309 are arranged mediolaterally opposite one another on the bearing element and are convexly curved in a circular arc. The sliding surfaces 308, 309 interact with the guide surfaces 207, 208 in a rotationally sliding manner about the pivot axis S. Proximodistal and thus along the longitudinal axis L, the aforementioned surfaces 207, 307, 208, 308 interact in a form-fitting manner. Furthermore, there is a form-fitting connection in the mediolateral direction.

[0034] The guide surfaces 207, 208 can also be referred to as medial guide surface 207 and lateral guide surface 208. In other words, the medial guide surface 207 lies on a medial side of the pivot axis S and / or the rod 100. The lateral guide surface 208, in contrast, lies on a lateral side of the pivot axis and / or the rod 100. The sliding surfaces 308, 309 can also be referred to as medial sliding surface 308 and lateral sliding surface 309. The medial sliding surface 308 is arranged on the medial outer side 307 or is formed by it itself. In this case, the latter is the case. The lateral sliding surface 309 is formed by the lateral outer side 306.

[0035] In the present case, the guide surfaces 207, 208 are each longitudinally extended parallel to the pivot axis S. Due to the straight and parallel longitudinal extension, the guide surfaces 207, 208 form a guideway E extending along the pivot axis S (see in particular Fig. 2 ). The reference block 200 and the bearing element 300 are translationally displaceable relative to each other along the guideway E. As a result, the reference block 200 can be positioned relative to the rod 100 and thus also to the femur F in different positions with respect to the anteroposterior axis. In other words, the reference block 200 can be positioned differently on the distal femur F with respect to its vertical axis (not further specified). As a result, the position of the reference block 200 can be easily and precisely adapted to femur bones of different sizes. As can be seen from Fig. 3 As shown, the reference block 200 is along the guideway E ( Fig. 2 ) is movable relative to the bearing element 300 between a lower end position and an upper end position. In e.g. Fig. 3 A positioning in the area of ​​the lower end position is shown. The upper end position is reached when the reference block 200 is moved from the Fig. 3 shown position with respect to the plane of the drawing upwards and until reaching a lower end of the guide surfaces 207, 208.

[0036] In the present case, the reference block 200 has a receiving slot 209 extending from the block rear side 201 to the distally opposite block front side 202. The receiving slot 209 is longitudinally extending straight parallel to the pivot axis S and / or the guide track E and has mediolaterally opposing inner walls 2091, 2092, on which the guide surfaces 207, 208 are arranged and / or formed. In the present case, the latter is the case. In addition, the receiving slot has an insertion opening 2093, which is arranged on the block underside 204. The insertion opening 2093 is configured for inserting the bearing element 300 into the receiving slot 209. The receiving slot 209 also has an end wall 2094. The end wall 2094 is located anteriorly opposite the insertion opening 2093 along the pivot axis S. The end wall 2094 forms a stop for the bearing element 300, more precisely: its upper side 304 (see Fig. 7 ).

[0037] In the embodiment shown, the receiving slot 209 divides the reference block 200 into a lateral block section 210 and a medial block section 211 (see in particular Fig. 6 ). Accordingly, the block back 201 is subdivided into a lateral block back and a medial block back (each without reference symbol).

[0038] As shown by Fig. 8 As shown, the surgical instrument system 1 comprises several different bearing elements 300, 300', 300". These can also be referred to as first bearing element 300, second bearing element 300' and third bearing element 300". The bearing elements 300, 300', 300" have a substantially identical design and function and differ only with regard to the orientation of the longitudinal axis L, L', L" of the respective receiving bore 301, 301', 301". The longitudinal axes L, L', L" are each longitudinally extended at a different inclination. The different angles of inclination are illustrated in relation to a normal direction N of the block rear side 201. The normal direction N is in Fig. 8 shown as an example for the second bearing element 300' and the third bearing element 300". In the first bearing element 300, the normal direction N coincides with the longitudinal axis L. The bearing elements 300, 300', 300" can each be attached to the reference block 200 in an interchangeable manner.

[0039] For disassembly, the bearing element 300 can be removed from the Fig. 2 shown configuration - can be pulled out of the receiving slot 209 in a posterior direction. The assembly is kinematically reversed. Due to the differently inclined longitudinal axes L, L', L", the reference block 200 can be optionally positioned at different inclination angles with respect to the femur F. In particular, the so-called flexion-extension angle can be adjusted easily and precisely. The longitudinal axes L, L', L" differ from one another in fixed angular steps. Consequently, the angular orientation of the reference block 200 can be adjusted in fixed, defined steps. The inclination of the reference block 200 is adjusted around a mediolaterally oriented axis that intersects both the pivot axis S and the longitudinal axis L.

[0040] In the embodiment shown, the surgical instrument system 1 also includes the aforementioned cutting block 400. The function and design of the cutting block 400 are generally known to those skilled in the art. The cutting block 400 serves to hold and guide a saw blade for resecting the distal condyles of the femur F. The cutting block 400 is releasably attached to the reference block 200 by means of a fixing device 212. Details of the fixing device 212 and the cutting block 400 are not essential to the present invention. Further explanations in this regard can therefore be omitted.

[0041] The compensation element 500 is designed to compensate for wear of the lateral distal condyle KL (not shown in detail) and is releasably attached to the block rear side 201 for this purpose. The compensation element has a proximodistal thickness (not shown in detail), which approximately corresponds to the wear of the lateral condyle KL. To compensate for varying degrees of wear, the surgical instrument system 1 in the present case has several different compensation elements 500, 500', 500" (see Fig. 4 ). For illustrative purposes, only the compensation element 500 is shown in detail. The compensation elements 500, 500', 500" have different proximodistal thicknesses and can be attached interchangeably to the block rear side 201. The compensation elements 500, 500', 500" and their attachment to the block rear side 201 are not essential to the present invention. Further discussions in this regard can therefore be omitted.

[0042] In the embodiment shown, the intramedullary rod 100 has a length of 175 mm. In embodiments not shown in the drawings, the length is between 120 mm and 250 mm.

[0043] The Fig. 9 bis 14 show a further embodiment of a surgical instrument system 1a according to the invention. Its function and design are essentially identical to the surgical instrument system 1 according to the Fig. 1 bis 7 To avoid repetition, the following primarily focuses on the essential differences between the surgical instrument system 1a and the surgical instrument system 1 according to the Fig. 1 bis 7 Functionally identical components and / or sections are identified by identical reference numerals with the addition of the lowercase letter "a." Functionally identical components and / or sections are not explained separately. Instead, explicit reference is made to the information provided regarding the surgical instrument system 1.

[0044] The surgical instrument system 1a differs primarily in a different implementation of the pivoting mobility between the reference block 200a and the bearing element 300a. For the purpose of pivoting support, an axis guide is provided in this case. The axis guide has axis elements 220a, 221a oriented coaxially to the pivot axis S as well as corresponding axis receptacles 320a, 321a (see in particular Fig. 12 ). In the present case, the axle elements 220a, 221a are assigned to the reference block 200a. The axle receptacles 320a, 321a are arranged and / or formed on the bearing element 300a.

[0045] The axle elements 220a, 221a are aligned coaxially with each other. The same applies analogously to the axle mounts 320a, 321a. The axle elements 220a, 221a and the axle mounts 320a, 321a interact in a sliding manner about the pivot axis S. For this purpose, one of the axle elements 220a, 221a engages axially in one of the axle mounts 320a, 321a. Both the axle elements 220a, 221a and the axle mounts 320a, 321a are aligned orthogonally to the longitudinal axis of the mounting bore 301a.

[0046] With respect to the longitudinal axis L, one can also speak of an anterior axis element 220a and a posterior axis element 221a. This also applies, mutatis mutandis, to the axis receptacles 320a, 321a.

[0047] The anterior axle mount 320a is recessed posteriorly into an upper side 304a of the bearing element 300a. The posterior axle mount 321a is recessed anteriorly into a lower side 305a of the bearing element 301a. Both axle mounts 320a, 321a are each inserted into the bearing element 300a in the form of a blind bore.

[0048] The axle elements 220a, 221a are each detachably secured to the reference block 200a and, in this case, are each screwed to a suitable thread of the reference block 200a in the form of a countersunk screw. To release the axle elements 220a, 221a, they are each equipped with a tool surface (not further specified) for receiving a complementary tool.

[0049] In the embodiment shown, the bearing element 300a is mounted in a hollow cylindrical projection 222a of the reference block 200a. The projection 222a has a receiving recess 223a ( Fig. 14 ), in which the bearing element 300a is pivotally mounted in the manner described above. The receiving recess 223a opens in the proximal direction into a passage 224a ( Fig. 14 ). The passage 224a serves to receive the distal rod end 102a, which can be guided from the block rear side 201a through the passage 224a and from there further via the receiving bore 301a through the reference block 200a.

[0050] In contrast to the bearing element 300 of the surgical instrument system 1, the bearing element 300a is not mounted on the reference block 200a in a linearly displaceable manner anteroposteriorly along the pivot axis S.

[0051] To still allow anteroposterior adjustability of the cutting block 400a, the fixing device 212a is displaceable relative to the reference block 200a. For this purpose, the reference block 200a has guide holes 225a ( Fig. 10 ), into which guide pins 2121a of the fixing device 212a engage axially.

[0052] Furthermore, the further function and design of the fixing device 212a are not essential with regard to the present invention, so that further explanations in this regard are unnecessary.

[0053] With regard to the function of the compensation element 500a, the statements made regarding the surgical instrument system 1 apply mutatis mutandis. Furthermore, several different compensation elements with different proximodistal thicknesses can be present.

[0054] With reference to Fig. 8The surgical instrument system 1a can, in turn, have several different bearing elements with differently inclined longitudinal axes, which can be interchangeably attached to the reference block 200a. To replace the bearing elements, the axis elements can be detached from the reference block 200a and reattached using the screw connection described above.

Claims

1. Surgical instrument system (1, 1a) for use in a knee joint replacement operation, having an intramedullary rod (100, 100a) which extends lengthwise between a proximal rod end (101, 101a) and a distal rod end (102, 102a) and is configured for introduction into the medullary space of a femur (F), and a reference block (200, 200a) which is pushed or can be pushed onto the distal rod end (102, 102a) and has a proximally oriented block rear side (201, 201a) configured to bear on distal condyles of the femur (F), wherein the reference block (200, 200a) is mounted or mountable on the distal rod end (102, 102a) by means of a bearing element (300, 300a), wherein the bearing element (300, 300a) has a reception bore (301, 301a) for coaxial and radially form-fit reception of the distal rod end (102, 102a) and is mounted on the reference block (200, 200a) in such a way as to be pivotable relative thereto at least about a pivot axis (S) oriented in an anteroposterior direction, characterized in that the at least one bearing element (300, 300a) is mounted releasably on the reference block (200, 200a), and in that a plurality of different bearing elements (300, 300', 300'') are provided that have differently inclined elongate reception bores (301, 301', 301''), wherein the reception bores (301, 301', 301'') are inclined differently, relative to a normal direction of the block rear side (201, 201a), in an anterior and / or posterior direction and can be mounted interchangeably on the reference block (200, 200a) for setting a flexion-extension angle of the latter.

2. Surgical instrument system (1) according to Claim 1, characterized in that the reference block (200) has a slide guide with guide faces (207, 208) that are concavely curved in the shape of an arc of a circle and lie opposite each other in a mediolateral direction, and in that the bearing element (300) has slide faces (308, 309) that are convexly curved in the shape of an arc of a circle and lie opposite each other in a mediolateral direction, wherein the slide faces (308, 309) are able to slide in rotation about the pivot axis (S) and formfittingly cooperate with the guide faces (207, 208) in translation in a proximodistal and mediolateral direction.

3. Surgical instrument system (1) according to Claim 2, characterized in that the guide faces (207, 208) each extend lengthwise in a straight line parallel to the pivot axis (S), wherein the slide faces (308, 309) cooperate with the guide faces (207, 208) along the pivot axis (S) in a translational sliding movement.

4. Surgical instrument system (1) according to Claim 2 or 3, characterized in that the reference block (200) has a reception slot (209), which reaches from the block rear side (201) to a block front side (202) lying opposite in a distal direction, extends lengthwise in a straight line parallel to the pivot axis (S) and has inner walls (2091, 2092), which lie opposite each other in a mediolateral direction and on which the guide faces (207, 208) are arranged and / or formed, wherein the reception slot (209) has, for the insertion of the bearing element (300), an insertion opening (2093) arranged in an anterior direction on a block upper side (203) or in a posterior direction on a block lower side (204) of the reference block (200).

5. Surgical instrument system (1a) according to Claim 1, characterized in that the reference block (200a) has an axial guide with at least one axial element (220a, 221a) oriented coaxially with respect to the pivot axis (S), and in that the bearing element (300a) has at least one axial recess (320a, 321a) oriented coaxially with respect to the pivot axis (S), wherein the axial element (220a, 221a) engages in the axial recess (320a, 321a) in such a way as to be able to slide about the pivot axis (S).

6. Surgical instrument system (1, 1a) according to any one of the preceding claims, characterized in that a plurality of different compensation elements (500, 500a, 500', 500'') having different proximodistal thicknesses are provided, which can be applied mutually interchangeably on the block rear side (201, 201a) in order to compensate for different degrees of wear of the distal condyles.

7. Surgical instrument system (1, 1a) according to any one of the preceding claims, characterized in that a cutting block (400, 400a) is provided, which is configured for guiding the cutting on the distal condyles of the femur (F) and is releasably fixed or fixable on a fixing device (212, 212a) of the reference block (200, 200a).

8. Surgical instrument system (1, 1a) according to any one of the preceding claims, characterized in that the intramedullary rod (100, 100a) has a length of between 120 mm and 250 mm, preferably of between 150 mm and 220 mm, particularly preferably of between 170 mm and 200 mm.