First metatarsophalangeal joint endoprosthesis

Abstract

The objective of this utility model is to reduce postoperative healing time by eliminating joint mobility in the early postoperative period. This objective is achieved by the proposed first metatarsophalangeal joint endoprosthesis, which has distal and proximal components comprising a distal articular cup and stem, as well as a proximal articular head and stem, respectively. The novelty of the proposed first metatarsophalangeal joint endoprosthesis lies in the distal articular cup's cylindrical shape, containing a socket at its base, elliptical in shape, with radii r1 and r2 in longitudinal and transverse sections, respectively, approximating the articular surface of the patient's metatarsal head. The distal articular cup has symmetrical lateral cuts with rounded corners, each with a radius of r3.The dorsal surface of the distal articular cup has a spherical surface with a radius of r4 to reduce bone resection of the first phalanx of the patient's foot. The proximal articular head has an elliptical base that transitions into a hemisphere with radii of r5 and r8 in longitudinal and transverse sections, respectively. On the sides, the proximal articular head has symmetrical lateral cuts with rounded corners with a radius of r7. Clinical results have demonstrated more effective compensation for damaged (destroyed) ligaments and reduced rehabilitation time (restoration of motion) in the postoperative period by eliminating joint mobility in the early postoperative period. Furthermore, the use of the proposed endoprosthesis reduces resection of the metatarsal head and the base of the phalanx during surgery.

Description

[0001] The utility model relates to the field of medicine, specifically to traumatology and orthopedics, and can be used in the treatment of small joints.

[0002] An endoprosthesis of the first metatarsophalangeal joint is known, comprising a distal articular cup with a stem and a proximal articular head with a stem, wherein the distal articular cup has the shape of a cylinder with a diameter D1 from 14.0 mm to 20.5 mm, and a thickness dl from 4.5 mm to 7.0 mm, and a spherical cavity with a depth of 1.7 mm to 3.1 mm, on the sides of the distal articular cup there are symmetrical lateral cuts, and on the lower side there is a dorsal mark, on the back side of the distal articular cup there is a corrugated surface, the stem of the distal articular cup is shifted downwards relative to its center by 0.5-1.5 mm and is made in the form of a truncated cone with an apex angle of 6 °, with a diameter of the upper base G1 from 5.4 mm to 7.2 mm and a length L1 from 17.0 mm up to 22.0 mm, on the leg of the distal articular cup there are 19-25 transverse grooves and four longitudinal grooves;the proximal articular head is made in the form of a segment of a sphere with a radius R from 7.5 mm to 11.0 mm and a thickness d2 from 5.4 mm to 8.6 mm, has an inclination of 10° relative to the axis of the stem, on the lower side the proximal articular head has a cut, on the back side of the proximal articular head there is a ribbed surface, the stem of the proximal articular head passes through the center of the back side of the proximal articular head and is made in the form of a truncated cone with an apex angle of 6°, a diameter of the upper base G2 from 5.1 mm to 7.2 mm and a length L2 from 17.0 mm to 30.0 mm, on the stem of the proximal articular head there are 14-30 transverse grooves and four longitudinal grooves (P№192022, RF).;

[0003] However, the use of this endoprosthesis for the treatment of small joints has a long healing period due to the mobility of the joint in the early period after surgery, since displacement of the articular surfaces is possible.

[0004] Also known is an endoprosthesis of the first metatarsophalangeal joint, having a proximal metatarsal component consisting of a proximal articular part and a stem, and a distal phalangeal component consisting of a distal articular part and a stem, wherein the stems of the endoprosthesis have the shape of a cylinder turning into a cone, while longitudinal grooves of a spiral shape are made on the stems, a visor is made on the dorsal surface of the proximal articular part, and a perpendicular cut is made on its plantar surface, wherein the shape of the articular part of the distal phalangeal component is made concave and close to the anatomical one, and a grooved cut is made on its dorsal surface, on the surfaces of the proximal and distal articular parts adjacent to the bone, six longitudinal and transverse grooves equally spaced from each other are made (PM No. 213559, Russian Federation) - prototype.

[0005] However, the use of this endoprosthesis for the treatment of small joints also has a long healing period due to the mobility of the joint in the early period after surgery, since displacement of the articular surfaces is possible.

[0006] The objective of the proposed endoprosthesis of the first metatarsophalangeal joint is to reduce the time of postoperative healing by eliminating joint mobility in the early postoperative period.

[0007] The stated problem is solved by the proposed endoprosthesis of the first metatarsophalangeal joint, which has distal and proximal components containing a distal articular cup and stem, as well as a proximal articular head and stem, respectively.

[0008] The novelty of the proposed endoprosthesis of the first metatarsophalangeal joint is that the distal articular cup has the shape of a cylinder, in which a cavity is made, at the base having the shape of an ellipse, having in the longitudinal and transverse sections radii r1, r2, respectively, close to the articular surface of the head of the metatarsal bone of patients, on the sides of the distal articular cup there are symmetrical lateral cuts with rounded corners, the radius of which is r3. The back side of the distal articular cup has a spherical surface with a radius r4, in order to reduce the resection of the bone of the first phalanx of the foot of patients, the proximal articular head has the shape of an ellipse at the base, turning into a hemisphere, having in the longitudinal and transverse sections radii r5, r6, respectively, on the sides of the proximal articular head there are symmetrical lateral cuts with rounded corners, the radius of which is r7.

[0009] Fig. 1 shows the distal component of the proposed first metatarsophalangeal joint endoprosthesis.

[0010] Fig. 2 shows the proximal component of the proposed first metatarsophalangeal joint endoprosthesis.

[0011] The distal component comprises a distal articular cup 1 and a stem 2. The distal articular cup 1 has a cylindrical shape in which a cavity 5 is made in the shape of an ellipse having radii r1 and r2 in longitudinal and transverse sections, respectively, close to the articular surface of the head of the metatarsal bone of patients. On the sides, the distal articular cup 1 has symmetrical lateral cuts 6 with rounded corners, the radius of which is r3. The back side of the distal articular cup 1 has a spherical surface with a radius r4, to reduce the resection of the bone of the first phalanx of the patient's foot, and also has a corrugated surface 7. The stem 2 is located in the center of the distal articular cup 1 and is made in the form of a truncated cone with an apex angle of 6 degrees, and also has transverse grooves 8 and longitudinal grooves 9.

[0012] The proximal component comprises a proximal articular head 3 and a stem 4. The proximal articular head 3 has an elliptical base that transitions into a hemisphere with radii r5 and r6 in its longitudinal and transverse sections. On the sides, the proximal articular head 3 has symmetrical lateral cuts 10 with rounded corners with a radius of r7. The back side of the proximal articular head 3 has a ribbed surface 11. The proximal articular head 3 has an inclination of 10° relative to the axis of the stem 4. The stem 4 of the proximal articular head 3 passes through the center of the back side of the proximal articular head 3 and is made in the form of a truncated cone with an apex angle of 6 degrees, and also has transverse grooves 12 and longitudinal grooves 13.

[0013] The above-described new features of the proposed endoprosthesis for the first carpometacarpal joint of the finger ensure a reduction in postoperative healing time by eliminating inflammatory processes, since they have increased initial stability.

[0014] All the new features listed are significant, as they allow for a positive clinical result, expressed in a reduction in the time of postoperative healing due to the elimination of inflammatory processes, as they have increased initial stability.

[0015] The claimed endoprosthesis was used in the clinic. We offer a step-by-step description of the surgical procedure.

[0016] 1. Preoperative assessment

[0017] X-rays of both feet are taken strictly in a standing position, with a load (the patient’s body weight): anterior and lateral projections.

[0018] Required to be assessed:

[0019] angle between the 1st and 2nd metatarsal bones (M1-M2); stability of the first metatarsocuneiform joint (1st TMT); position of the 1st metatarsal bone (varus, equinus, elevation), presence of Hallux Valgus;

[0020] Lelievre's parabola configuration;

[0021] metatarsal length meets Maestro criteria.

[0022] 2. Treatment strategy for identified deformities

[0023] If available:

[0024] M1-M2>12°,

[0025] instability of the first metatarsocuneiform joint,

[0026] elevation or equinus of the first metatarsal bone, - it is recommended that the first stage be arthrodesis of the first metatarsal joint using the Lapidus / Albrecht procedure (Lapidus procedure).

[0027] After correction of the first ray axis and confirmation of stability, the second stage of endoprosthetics of the first metatarsophalangeal joint is performed; it is also possible to perform a simultaneous Lapidus / Albrecht operation with total endoprosthetics of the first metatarsophalangeal joint.

[0028] 3. Surgical approach

[0029] A dorsomedial approach is taken to the first metatarsophalangeal joint 3-4 cm.

[0030] The capsule is opened, the joint is mobilized and the condition of the cartilage is assessed.

[0031] 4. Resection of articular surfaces

[0032] Anatomically oriented resection is performed:

[0033] Mobilization of sesamoid bones (if fused), separation of sesamoid bones with a chisel.

[0034] Removal of osteophytes of the metatarsal bone and proximal phalanx, taking into account the preservation of bone cortices.

[0035] A 2.5 mm Steinmann wire is inserted, a resection filing template No. 1 for resection of the metatarsal bone is installed along the anatomical axis of the first metatarsal bone, and is additionally fixed to the bone with 1.0-1.2 mm wires.

[0036] The head of the first metatarsal bone is resected at an angle of 100° to its longitudinal axis.

[0037] Resection volume: no more than 4 mm of bone.

[0038] At the same time, we maintain the position of the head of the first bone in Lelièvre's parabola.

[0039] If the position of the head of the first bone does not reach the parabola of Lelièvre, then resection filing template No. 2 is installed for additional resection.

[0040] Maestro criteria are taken into account (length tolerance: M1≈ M2±1-2 mm).

[0041] Dorsal osteophytes are removed if necessary without disturbing the plantar inclination.

[0042] A 2.5 mm Steinmann wire is inserted along the anatomical axis of the main flank of the first finger, and the phalangeal part for the distal component is processed along the wire using a cannulated milling head.

[0043] Trial components are tried on, movement is performed in the first metatarsophalangeal joint; the range of motion is assessed, which should be close to physiological and amount to at least 40-50° in total (dorsiflexion + plantar flexion).

[0044] If the range of motion is insufficient, the resection level of the first metatarsal bone and the main phalanx is assessed under the control of the EOP, as well as the correction of the filings and the relationship of the test components, taking into account the Lelièvre parabola and the Maestro criteria.

[0045] If ​​necessary, additional correction of the filings is performed to achieve a range of motion close to physiological, within 40-50° of total amplitude.

[0046] 5. Channel preparation

[0047] A 2.5 mm Steinmann wire is inserted along the anatomical axis of the first metatarsal bone and the proximal phalanx of the first toe. Based on the selected dimensions of the future components, the metatarsal canal and proximal phalanx are reamed with a suitable cannulated drill to the mark, strictly along the anatomical axis, under image intensifier guidance, to reduce the risk of cortical bone perforation.

[0048] The channels are expanded with appropriate compactors to the required leg size.

[0049] 6. Implantation of components of the claimed endoprosthesis

[0050] Installation of unbonded ceramic prosthesis:

[0051] The proximal component (in the metatarsal bone) is installed with a striking impactor.

[0052] The distal component (in the proximal phalanx) is installed using a striking impactor.

[0053] Final image intensifier control is in progress.

[0054] The stability of the components, traction and biomechanics of the joint are checked.

[0055] 7. Completing the operation

[0056] The capsule and skin are sutured layer by layer.

[0057] If the first metatarsophalangeal joint replacement did not require additional reconstruction or correction of deformity, immobilization is generally not required in the postoperative period; orthopedic shoes such as Baruk are recommended for a period of 8 to 12 weeks.

[0058] In case of performing an additional arthrodesis procedure using the Lapidus or Albrecht method, weight bearing on the operated foot is permitted only after confirmed formation of a bone block in the area of ​​the first metatarsocuneiform joint (I TMT), according to X-ray control data.

[0059] X-ray control and subsequent load according to the patient’s well-being are carried out.

[0060] 8. Development of movements in the first metatarsophalangeal joint

[0061] If no accompanying reconstructions were carried out (e.g. Lapidus / Albrecht):

[0062] Start of active movements - 2-3 days after surgery.

[0063] Passive and active exercises within a painless range, if possible under the supervision of exercise therapy or the patient.

[0064] The goal is to maintain amplitude, avoid capsule fibrosis, and prevent rigidity.

[0065] If arthrodesis of the first metacarpophenoid joint was performed according to (Lapidus):

[0066] Development of movements in the metatarsophalangeal joint is possible after 3-4 weeks, provided that fixation is stable and there are no signs of instability of the first metatarsophalangeal joint on the x-ray.

[0067] With aggressive rehabilitation before 3 weeks, there is a risk of micromovements in the area of ​​future arthrodesis of the first metatarsal joint, increasing the risk of non-union.

[0068] The proposed first metatarsophalangeal joint endoprosthesis was used in 5 patients. Clinical results demonstrated more effective compensation for damaged (destroyed) ligaments and reduced rehabilitation time (restoration of motion) in the postoperative period due to the elimination of joint mobility in the early postoperative period. Furthermore, the use of the proposed endoprosthesis reduces the resection of the metatarsal head and base of the phalanx during surgery.

Claims

An endoprosthesis of the first metatarsophalangeal joint, having a distal and proximal components containing a distal articular cup and stem, as well as a proximal articular head and stem, respectively, characterized in that the distal articular cup has the shape of a cylinder in which a cavity is made, at the base having the shape of an ellipse, having in the longitudinal and transverse sections radii r1, r2, respectively, close to the articular surface of the head of the metatarsal bone of patients, on the sides the distal articular cup has symmetrical lateral cuts with rounded corners, the radius of which is r3, the back side of the distal articular cup has a spherical surface with radius r4 and a corrugated surface, the stem of the distal component is located in the center of the distal articular cup and is made in the shape of a truncated cone with an apex angle of 6 degrees, and also has transverse grooves and longitudinal grooves, the proximal articular head has at the base the shape of an ellipse, turning into hemisphere,having in longitudinal and transverse sections radii r5, r6 respectively, on the sides the proximal articular head has symmetrical lateral cuts with rounded corners, the radius of which is r7, the back side of the proximal articular head has a ribbed surface, the proximal articular head has an inclination of 10 degrees relative to the axis of the stem, the stem of the proximal articular head passes through the center of the back side of the proximal articular head and is made in the form of a truncated cone with an apex angle of 6 degrees, and also has transverse grooves and longitudinal grooves.

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