Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/80—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
  • A61B17/8061—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates specially adapted for particular bones
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/80—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
  • A61B17/8085—Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates with pliable or malleable elements or having a mesh-like structure, e.g. small strips
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S606/00—Surgery
  • Y10S606/902—Cortical plate specifically adapted for a particular bone
  • Y10S606/906—Small bone plate

Definitions

• the present disclosure generally relates to medical devices for use in correcting foot deformities, and methods for surgically installing such devices and correcting such deformities.
• Bunions have long been one of the more common types of painful foot deformities.
• the technical name for this type of deformity is Hallux Abducto Valgus (HAV), which is generally described as a medial deviation of the first metatarsal accompanied by a lateral deviation and/or valgus rotation of the hallux (or “big toe”).
• HAV Hallux Abducto Valgus
• the result effect is a subluxation of the big toe joint (or first metatarsophalangeal joint (MTPJ)) creating a boney prominence (or eminence) on the inside of the foot, near the base of the big toe.
• MTPJ first metatarsophalangeal joint
• IA illustrates the normal anatomical configuration of a left human foot, which includes the first metatarsal 10 that extends between the medial cuneiform 12 and the hallux 13.
• the first metatarsal 10 articulates with the medial cuneiform 12 at the first metatarsocuneiform joint 14 at its most proximal aspect; and is further connected to the hallux 13 at the metatarsophalangeal joint 15 at its most distal aspect.
• the second metatarsal 16 Located adjacent (lateral) to the first metatarsal 10 is the second metatarsal 16, which articulates with the intermediate cuneiform 17 at the second metatarsocuneiform joint 18.
• the joint between the medial cuneiform 12 and intermediate cuneiform 17 is the intermetatarsocuneiform joint 18.
• the sesamoids 19 are located beneath (plantar to) the first metatarsal head at the first MTPJ, and articulates with the head of the first metatarsal.
• FIG. IB illustrates the resulting anatomical configuration of a human foot experiencing HAV.
• the first metatarsal 10 extends from the medial cuneiform 12 and deviates medially while the hallux 13 deviates laterally.
• the sesamoids 19 may rotate with the first metatarsal 10. This condition may lead to painful motion of the big toe joint and/or difficulty fitting footwear.
• Other conditions associated with HAV may include: hammer toe formation of the adjacent toes, forefoot pain on the ball of the foot (aka metatarsalgia), stress fractures of the adjacent metatarsals, flat feet (pes planus), and arthritis of the first MTPJ or midfoot.
• Bunions may occur from a variety of causes, such as genetic factors, gender influences, biomechanical and structural causes, trauma (injury), and certain shoes. Some physicians believe genetics play a large role in the development of bunions. Dudley Morton suggested that bunions may be a result of evolutionary influence, and described a certain foot type that is associated with bunions - the so called Morton's foot (a condition where the first metatarsal is shorter than the other metatarsals. See Morton DJ. The Human Foot: Its evolution, Physiology and functional Disorders. Columbia University Press, Morningside Heights, NY, 1935.
• the most commonly utilized radiographic measurement is the intermetatarsal angle (IMA), which measures the angle between a longitudinal bisection of the first and second metatarsal shafts.
• IMA intermetatarsal angle
• the IMA essentially measures the extent with which the first metatarsal has deviated (medially) from the second metatarsal.
• the normal value for the IMA is less than 8 degrees.
• HAA hallux abductus angle
• HAA essentially measures the extent with which the hallux has deviated (laterally) from its native position (nearly rectus with the more proximal metatarsal).
• the normal value for the HAA is less than 12 degrees.
• a patient with a mild HAV deformity may have an IMA of 10-12 degrees and an HAA of 21-30 degrees.
• a patient with a moderate HAV deformity may have an IMA of 12-16 degrees and an HAA of 31-40 degrees.
• a patient with a severe HAV deformity may have an IMA of greater than 16 degrees and an HAA of greater than 40 degrees.
• a common technique involves an osteotomy (bone cut) procedure in which the first metatarsal is broken into two pieces and the distal portion of the bone is translated closer (medially) to the adjacent second metatarsal.
• the osteotomy may be performed at several locations on the first metatarsal, depending on the severity of the deformity. Less severe HAV deformities are typically corrected with an osteotomy near the head (10a in Fig. 1) of the first metatarsal, whereas moderate and larger deformities are corrected with an osteotomy near the base (10b in Fig. 1) of the first metatarsal.
• the procedure may involve an isolated fusion of the 1 st MCJ, and in other situations surgeons may also incorporate a fusion of the intermediate cueniform area and or 2 nd metatarsal base.
• the idea behind the Lapidus approach is to permanently fuse the base of the first metatarsal to the medial cuneiform bone in a corrected new position. This permanent fixation is carried out by first reducing the IMA and then fusing the MCJ. Implementation of this approach often involves the use of a number of screws across the joint or a plate that can accommodate screws to attach the plate to the metatarsal and medial cuneiform.
• a fusion of the 1 st MCJ that incorporates lengthening of the entire segment by adding bone graft (i.e., a block of bone) into the fusion site is better termed a distraction Lapidus.
• the present disclosure generally relates to an improved fixation or
• Lapidus plate for use in treating HAV deformities or other conditions that may call for a fusion of this joint and possibly concomitant fusion incorporating the 2 nd metatarsal base and/or intermediate cuneiform.
• the term “Lapidus” as used herein is only meant to be descriptive in terms of a suggested use for the plate and does not confer any structural limitations on the plate described herein.
• the Lapidus plate is used for joint arthrodesis at the first MCJ.
• the Lapidus plate according to the present disclosure provides mechanical stability of the first metatarsal while also accommodating and assisting reorientation of the first metatarsal to correct the HAV deformity.
• the plate is generally elongated and comprises a thin and rigid stabilizing member of biocompatible material.
• the orientation of the fixation plate offers multiplanar stability including the plantar aspects of the joint to resist tensile forces transmitted across the fusion site.
• the screw configuration of the plate can be maintained for several different sizes of the plate while still maintaining desired multiplanar stability.
• the positioning of the screw holes are designed to avoid invasion of the fusion site by the screws that ultimately pass therethrough. Indeed, the screw angles are designed for the post-Lapidus position.
• the Lapidus plate according to the present disclosure includes additional features that accommodate the desired reorientation of the first metatarsal during correction.
• the Lapidus plate described herein includes a degree of twist along its longitudinal axis to follow the contour of the first metatarsal and medial cuneiform, thereby facilitating reorientation of the first metatarsal to its natural position.
• the Lapidus plate is further anatomically configured to include a recess, which accommodates the natural crests of the medial cuneiform and the first metatarsal. In this manner, the first metatarsal can be guided against the medial cuneiform and the plate such that the base of the first metatarsal fits within the recess.
• the recess thus facilitates a desired location and orientation of the first metatarsal that approximates its natural position.
• the Lapidus plate according to the present disclosure accommodates the final position of the fusion of the MCJ.
• the fixation plate is anatomically configured to provide rigid support of the realigned MCJ fusion site while positioning screws to avoid invasion into the fusion site thus achieving desired stability. It is to be appreciated that the plate described herein can be adapted for use on both right and left feet with a right foot plate being a mirror-image of a left foot plate.
• a surgical method for preparing the MCJ for receipt of the Lapidus plate and subsequently implanting the plate is further described.
• surgical procedures may be concomitantly performed near the first metatarsal head.
• a capsular release of the first MTPJ and resection of the medial eminence, if present, is often performed in conjunction with release of the adductor tendon and lateral sesamoidal ligament.
• all cartilage is removed from the first MCJ with either a reciprocal saw and/or manual resection. Removal of the cartilage is preferred to allow for bone on bone contact to allow for a fusion between the medial cuneiform and first metatarsal.
• the first metatarsal is then repositioned back to its native position (IMA as close to zero as possible).
• IMA as close to zero as possible.
• the first metatarsal must be translated inferiorly and/or angulated inferiorly (plantarflexed) to restore the weightbearing mechanics of the first metatarsal head at the ball of the foot.
• the fusion site is stabilized with the fixation plate described herein.
• the plate is placed on the dorsal medial surface of the segment to avoid contact with muscular attachments.
• FIGURE IA illustrates a top view of a human foot
• FIGURE IB illustrates a top view of a human foot experiencing the condition of Hallux Valgus
• FIGURE 2 illustrates a top view of a fixation plate according to one embodiment of the present disclosure
• FIGURE 3A illustrates a side view of the fixation plate of Figure 2
• FIGURE 3B illustrates a side view of the fixation plate of Figure 2 positioned adjacent to the MCJ;
• FIGURE 4 illustrates a schematic view depicting the gradual twist of the fixation plate of Figure 2;
• FIGURE 5 A illustrates a perspective view of the fixation plate of Figure
• FIGURE 5B illustrates another perspective view of the fixation plate of
• Figure 2 positioned against the medial cuneiform and first metatarsal
• FIGURE 6 illustrates a top view of the fixation plate of Figure 2 affixed to the medial cuneiform and first metatarsal;
• FIGURE 7 is a bottom perspective view of the fixation plate of Figure 6 showing the orientation of the screws.
• FIGURE 8 is a perspective view of another embodiment of the fixation plate wherein the plate is a distraction plate.
• a Lapidus plate 20 for a human left foot according to the present disclosure is illustrated in Fig. 2. It is to be appreciated that a Lapidus plate according to the present disclosure for a human right foot would be substantially similar to and have a mirror image configuration of the plate 20 illustrated in Fig. 2.
• the plate 20 generally comprises a distal portion 22 for attachment to a metatarsal and a proximal portion 24 for attachment to a cuneiform.
• the distal and proximal portions 22, 24 are divided along a joint axis (J) generally corresponding to the fusion site (i.e., the interface between the cuneiform and metatarsal) as will be described.
• the metatarsal is the first metatarsal 10 (Fig. 1) and the cuneiform is the medial cuneiform (Fig. 1).
• the plate 20 is sized and shaped to conform to the anatomical contours of the first MCJ and as such the distal portion 22 includes a relatively narrow and rounded end portion 26. The distal portion gradually increases in width along a first side 28 of the plate towards the proximal portion 24.
• the proximal portion 24 includes a slight gradual increase in width along the first side 28 of the plate 20 culminating in a rounded end portion 30 that is larger in width than the end portion 26 of the proximal portion 22.
• the plate 20 further includes a substantially linear second side 32 opposite the first side 28.
• the plate is configured and designed to avoid tendon and minimize soft tissue irritation, while also providing for optimal rigidity and stability.
• the end portion 26 of the distal portion 22 has an anatomically optimal width Wi in the range of 10.5 +/- 3mm, while the end portion 30 of the proximal portion 24 has an anatomically optimal width W 2 in the range of 16 +/- 4mm.
• the plate has a varying thickness of between 0.75mm and 3.0mm, thus minimizing tissue irritation.
• the edges of the plate may be tapered.
• the Lapidus plate according to the present disclosure is sized and shaped for placement in a "safe zone" of the area to be treated; that is, the place on the dorsal medial surface of the first metatarsal and medial cuneiform that is devoid of tendon attachments. It is to be appreciated that the Lapidus plate according to the present disclosure may have a configuration different than that described herein so long as the plate accommodates the contours of the particular anatomical region being treated.
• the distal and proximal portions 22, 24 of the plate 20 each include a plurality of screw holes formed therethrough to facilitate attachment of the plate to the respective metatarsal and cuneiform.
• the distal portion 22 includes four screw holes formed through the plate 20 with two holes 40, 42 being positioned in proximity to the joint axis J and the remaining two holes 44, 46 being positioned distal of holes 40, 42.
• the holes 40, 42 and 46 are countersunk and threaded to accommodate screws having threaded heads as will be described.
• Hole 40 is positioned adjacent to the second side 32 and the joint axis J while hole 42 is positioned distal of hole 40 and closer to side 28 of the plate 20.
• Hole 44 is positioned distally of holes 40, 42 and is generally elongated to accommodate movement of the plate 20 as will be described.
• the elongated nature of hole 44 defines a pair of substantially parallel sides 47, 49, which are substantially parallel to second side 32 of the plate 20.
• Hole 46 is positioned distal of hole 44 and also accommodates a screw (not shown) to assist with fixation of the plate 20 to the metatarsal. The location of hole 46 assists with distributing weight away from the fusion site.
• the proximal portion 24 includes a plurality of screw holes to accommodate fixation.
• the proximal portion 24 of the plate 20 includes three holes 48, 50 and 52 formed therethrough.
• the holes 48, 50 and 52 are countersunk and threaded to accommodate screws having threaded heads as will be described.
• Hole 48 generally corresponds to hole 40 of the metatarsal portion, and as such, is positioned adjacent to the second side 32 and the joint axis J.
• Hole 50 generally corresponds to hole 42 of the metatarsal portion, and as such, is positioned proximal of hole 48 and closer to side 28 of the plate 20.
• Hole 52 is positioned proximal of holes 48, 50 and accommodates a screw (not shown) to assist with fixation of the plate 20 to the cuneiform bone. The location of hole 52 assists with distributing weight away from the fusion site.
• the holes 40, 42 of the distal portion 22 and the holes 48, 50 of the proximal portion are designed to assist with screw fixation into the widest part of both bone segments while maintaining a safe distance from the fusion site such that the screws that ultimately pass through such holes do not penetrate the fusion site.
• the holes 40, 42, 48 and 50 form a substantially trapezoidal shape, which facilitates the even distribution of load across the MCJ. It is to be appreciated that the arrangement of holes 40, 42, 48 and 50 may not form an exact trapezoid.
• the line defined from the centerpoint of hole 40 to the centerpoint of hole 48 and the line defined from the centerpoint of hole 42 to the centerpoint of hole 50 may not be perfectly parallel.
• Such lines may be only substantially parallel and thus the arrangement of holes 40, 42, 48 and 50 may form a substantially trapezoidal shape rather than a true trapezoidal shape.
• the substantially trapezoidal arrangement of the holes 40, 42, 48 and 50 define an angle ⁇ measured between the non-parallel sides of the trapezoid (i.e., between the lines Ai and A 2 shown for purposes of illustration in Fig. 2). Also, the distance between the dorsal screw holes
• the angle ⁇ is optimally
• the plate 20 further includes a recess 60 defined along a bone-contacting surface 62 of the plate.
• the recess 60 is generally defined at and adjacent to the joint axis J of the plate 20.
• the plate 20 is designed to accommodate the crests of the first metatarsal 10 and medial cuneiform 12 upon placement of the plate against the MCJ as illustrated in Fig. 3B.
• a channel 64 is formed laterally in the bone-contacting side of the plate 20 in a region generally corresponding to the recess 60 to facilitate additional flexibility at the fusion site along the joint axis J (Fig. 2). This flexibility assists the surgeon with bending of the plate 20 to achieve the desired final position of the plate at the fusion site.
• the first metatarsal experiences a lateral twist.
• the plate 20 includes a degree of twist along its longitudinal axis (i.e., from end portion 30 to end portion 26 as shown in Fig. 2).
• the plate 20 has a gradual twist ⁇ from proximal portion 24 to distal portion 22.
• the anatomically optimal twist is 12 +/- 6 degrees measured along the longitudinal axis of the plate 20 defined from end portion 30 to end portion 26.
• the first MCJ is prepared for plate implantation by first performing a capsulotomy of the ligaments surrounding the first MCJ and then removing cartilage within this joint.
• the proximal portion 24 of the plate 20 is placed against the medial cuneiform 12 and attached thereto using screws 70 having threaded heads and threaded shafts.
• the threaded heads of the screws 70 thread into the corresponding countersunk threaded holes 48, 50 and 52 (Fig. 2) such that the screws are fixed relative to the plate 20.
• the screws may have non-threaded heads such that the screws are not locked into place relative to the plate 20.
• the first metatarsal 10 Upon attachment of the plate 20 to the medial cuneiform 12, the first metatarsal 10 is translated inferiorly in the direction I as illustrated in Fig. 5B to maintain a natural distribution of ground force over all the foot's sesamoid bones to avoid stress fracture or even breakage of the other four metatarsals.
• the optimal amount of translation Di is 3 +/- 3mm to accommodate for the shortening that occurs when cartilage is removed from the joint.
• the first metatarsal 10 is also translated laterally and rotated in the direction R to return the metatarsal to its approximate natural anatomic orientation to reduce the intermetatarsal angle.
• the plate 20 according to the present disclosure is designed for placement against the medial cuneiform and first metatarsal in an area devoid of muscular and tendinous attachments.
• the MCJ may be temporarily fixated in a corrected position using a k-wire.
• the plate 20 may include k-wire holes such that k-wires can be used in conjunction with the plate to stabilize the first metatarsal for screw implantation.
• the first metatarsal 10 is then moved toward the medial cuneiform 12 whereupon the screw positioned through elongated hole 44 is tightened to compress the first MCJ.
• the distal portion 22 of the plate 20 is further attached to the metatarsal using threaded screws 70 having threaded heads that are placed through screw holes 40, 42 and 46 (Fig. 2) and into the bone.
• the threaded heads of the screws 70 thread into the corresponding countersunk threaded holes 40, 42 and 46 such that the screws are fixed relative to the plate 20.
• the screws may have non-threaded heads such that the screws are not locked into place relative to the plate 20.
• the twist of the plate 20 along its longitudinal axis facilitates desired orientation of the screws into the metatarsal. More specifically, holes 40 and 42 are angled toward one another such that implantation of the screws 70 through these holes results in their axes crossing one another in a divergent manner. This, in turn, provides for optimal orientation of the screws 70 in the first metatarsal 10 to achieve desired stability.
• a variation of the Lapidus plate according to the present disclosure involves providing for distraction (or lengthening) at the fusion site. As illustrated in Fig. 8, this allows for bone graft 80 to be interposed between the 1 st metatarsal base 10b and the medial cuneiform 12, when the clinical situation arises. Providing for distraction at the fusion site maintains that the screw holes 40 and 42 purchase the 1 st metatarsal base 10b, for which these holes are configured to provide maximal stability at the fusion site. The amount of distraction D' most commonly required is between lmm - 25mm, with the distraction plate accommodating this length. It is to be appreciated, however, that other distraction lengths may be accommodated by the plate 20 of the present disclosure.
• the plate 20 may add length by providing additional screw holes formed in distal portion 22 of the plate 20. In some embodiments, fixation of the plate may occur via a screw passing through the fusion site into the intermediate cuneiform and/or second metatarsal.
• the Lapidus plate 20 described herein and associated method of implantation leads to fusion of the MCJ, which provides for mechanical stability of the first metatarsal and medial cuneiform and the reorientation to compensate for an HAV deformity.
• the orientation of the fixation achieved according to the principles of the present disclosure offers multiplanar stability including the plantar aspects of the MCJ to resist tensile forces across the fusion site.
• the screw configuration described herein can thus be maintained for several different sizes of distraction Lapidus arthrodesis. That is, the screw configuration provides multiplanar stability as distraction length is added to the plate 20.

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• 2008
  • 2008-11-19 US US12/274,199 patent/US8828063B2/en active Active
• 2009
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