Apparatus and method for canine elbow correction

Abstract

The present invention relates to devices and methods for correcting paw misalignment in the forelimbs of dogs and other animals. Paw realignment is intended to properly align the medial compartment of the elbow with the distal end of the humerus.

Description

[Technical field]

[0001] The present invention relates to devices and methods for correcting paw misalignment in the forelimbs of dogs and other animals. Paw realignment is intended to properly align the medial compartment of the elbow with the end of the humerus. [Background technology]

[0002] Arthritis of the elbow joint is the most common cause of forelimb lameness in dogs. The majority of arthritic disorders of the elbow are considered to be forms of dysplasia. Common causes of dysplasia include fragmented coronoid process (FCP) and medial compartment disease (MCD). In FCP, the most common form of elbow dysplasia in dogs, a fragment of bone and / or cartilage of the ulna breaks. The fragment can move and cause further damage to the joint. The broken bone further changes the relationship between the abutting surfaces of the humerus and ulna. This change in relationship causes a misalignment of the forces acting on the joint, especially when loaded. The misaligned forces can cause damage to the cartilage and / or further damage to the bone.

[0003] Treatment of FCP requires removal of any bone fragments. However, this may not be sufficient if the joint is otherwise damaged. If the joint is severely damaged or the bone is displaced, the joint may become further damaged and lameness may continue.

[0004] One method to correct elbow problems is to replace all or part of the joint. However, elbow replacement requires extensive and complex surgery. Although a variety of elbow prostheses exist, none have been proven safe and effective for routine use.

[0005] The sliding humeral osteotomy (SHO) was proposed by Dr. Schultz at the University of California, Davis Orthopedic Research Laboratory. This procedure realigns the humerus and transfers forces away from the area of ​​cartilage damage. In this procedure, the humerus is cut above the elbow. A plate is used to reposition part of the humerus.

[0006] The proximal abducting ulnar osteotomy, developed by Dr. Pfeil (Dresden, Germany) and described in WO 2010 / 121233, shifts the distal forelimb outward (lateral) and realigns the load through the elbow to a more lateral position, thus reducing the load located on the ulnar surface and medial condyle of the femur and shifting the load to the outside of the joint.

[0007] A bi-oblique proximal osteotomy of the ulna exists which is useful for balancing the distribution of forces between the medial and lateral sides of the elbow joint. This method is useful in dogs from about 6 to 12 months of age.

[0008] Distal ulnar osteotomy can be performed to achieve the same results as the biclinic technique, but is only applicable in much younger dogs (4-6 months of age).

[0009] A distal abducting ulnar osteotomy (DAUL) repositions the load through the elbow to a more lateral position, thus reducing the load located on the ulnar surface and medial condyle of the femur and shifting the load to the lateral side of the joint. Summary of the Invention

[0010] [Disclosure of the Invention] The present invention provides a method and apparatus for realigning the foot of a mammal, particularly a dog, to the sagittal plane by adjusting the twist of the ulna. The twist of the ulna is corrected by cutting the ulna into two parts, preferably near the distal end of the bone. To adjust the twist of the ulna, a plate is provided for attachment to the ulna. The plate has a proximal and a distal portion. One portion is straight and the other portion is angled about the long axis of the plate. Different plates may have different angles of twist. A plate with the desired twist angle is selected to achieve the correct twist of the ulna to align the foot with the sagittal plane. The twist of the plate is either clockwise or counterclockwise for left or right sided applications. The plate is preferably adapted for attachment to the lateral-caudal aspect of the ulna. The cut is easiest to make towards the distal end, but may be made anywhere between the distal and proximal ends, provided there is enough space for the plate to rest on the bone without violating the joint.

[0011] The first aspect of the invention relates to a procedure for realigning the humerus and ulna of a dog or other mammal's elbow to correct an altered shape of the head of the ulna from an injury to the elbow joint, such as FCP. The ulna is amputated above the wrist joint. The twist of the lower part of the ulna is adjusted so that the outward angle of the foot is adjusted to the normal direction, between 5-10 degrees. In many cases, due to injuries to the elbow joint, the outward angle of the foot reaches more than 60 degrees. Once the foot has been rotated to the correct position, the ulnar twist is fixed in this position using a special plate and screw implant, fixing the two parts of the ulna together at the new angle.

[0012] According to another aspect of the invention, paw twist is measured when the forelimb is held in an extended position and the wrist is hyperextended. Measurement of the outward twist angle of the paw in this position is used to determine error in alignment.

[0013] The required change in the twist angle of the lower ulna is determined based on the deviation, measured by the increase in the outward direction of the foot. Once the cut is made to the distal ulna, the foot is rotated to its normal position with 0-10 degrees outward twist.

[0014] According to another aspect of the invention, a plate for reconnecting severed portions of the ulna is provided. The plate has two flat portions twisted relative to each other. One flat portion of the plate is adapted to be attached to the upper portion of the ulna. Another flat portion of the plate is adapted to be attached to the lower portion of the ulna. The upper and lower flat portions of the plate are twisted about the long axis of the plate. The plate is adapted to be attached to each portion of the ulna by a fastening means, typically a bone screw. According to another aspect of the invention, plates are provided for right and left sides with various degrees of twist angle. The plate used depends on the desired adjustment of the twist angle required to fasten the plate to the lateral surface of the ulna above and below the incision.

[0015] The devices and methods of the present invention are particularly useful in veterinary medicine, and more particularly in the treatment of dogs. [Brief description of the drawings]

[0016] [Figure 1] Diagram of normal dog forelimb skeleton and sagittal plane. The mechanical axis of the elbow joint is indicated by a line projecting laterally from the lateral epicondyle of the humerus and medially from the medial epicondyle of the humerus. The sagittal plane is perpendicular to this axis. In this case, the axis of the foot is aligned with the sagittal plane. [Diagram 2] Diagram of the forelimb skeleton and sagittal plane of a dog. In this view, the axis of the paw does not coincide with the sagittal plane, but is externally rotated by an angle β. [Diagram 3] A perspective view of the plate, with holes for receiving screws. The underside of the plate contacts the bone only at points on each side of the screw holes. There is an angular twist in the plate between the distal and proximal sections of the plate. The plate is used to connect the distal and proximal portions of the ulnar osteotomy and induce twist between the two bone sections. [Figure 4]Side view of a plate used to fix the distal ulna in a rotated orientation. [Diagram 5] End view of the plate. Various plates are prepared with different twist angles. Plates also need to be made in mirror image for the right and left side. The angle α can be as small as 5 degrees and as large as 50 degrees. [Figure 6] View of the ulna with the plate applied distally. The plate is placed on the caudal-lateral aspect of the ulna. The distal component is now internally rotated to correct the torsion of the ulna. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the normal position of the bones involved in the elbow joint: the humerus 1, radius 2, and ulna 3. The mechanical axis 52 of the joint is often seen as a vector passing through the medial epicondyle 1″ of the humerus and the lateral epicondyle 1′ of the humerus. The sagittal plane 50 is perpendicular to this axis at the level of the center of the elbow joint. The foot, consisting of the carpal bones, a set of longitudinal metacarpals 4, and the phalanges, is either aligned with the sagittal plane (51) or slightly rotated outward by 5–10 degrees in a normal elbow when the foot is extended.

[0018] When the joint is loaded, i.e. when the dog is standing, the humerus is supported evenly across the heads of the radius 2 and ulna 3. However, when there is elbow dysplasia, the bones do not interact evenly and the axis of the foot 51 is externally rotated an angle β much greater than the normal 5-10 degrees, as shown in Figure 2.

[0019] 3, 4, and 5 illustrate a plate 100 for use in correcting foot misalignment by realigning the ulnar torsion. The plate 100 is elongated with a proximal portion 100′ and a distal portion 100″. It is similar to other types of plates for attachment to bone. It can be of any material, but is preferably metal. The surface can be formed or treated to allow in-growth or on-growth of the bone. The plate 100 has a first side 101 and a second side 103 opposite the first side 101 in the proximal portion 100′, and a first side 102 and a second side 104 opposite the first side 102 in the distal portion 100″. The first sides 101 and 102 are preferably flat. The second sides 103 and 104 preferably have a non-planar surface to limit contact with the bone. More preferably, the second sides 103 and 104 are shaped to contact the bone only around the screw holes 120. The other sides 106, 107, 108, and 109 may also be planar or have a variety of other shapes. As is known for bone plates, the sides 106, 107, 108, and 109 may be curved around the screw holes 120. The plate 100 has a number of screw holes 120 for receiving bone screws for attaching the plate to the bone. Preferably, the screw holes 120 are recessed so that the heads of the screws are located below the first sides 101 and 102 of the plate. Of course, other types of screw holes may be used. Any type of bone screw, including locking and non-locking screws, may be used to attach the plate 100 to the ulna. Different types of screws may be used for different holes. The plate 100 in Figures 3 and 4 is shown with six screw holes 120. However, any number of screw holes may be used, for example, 4, 6, or 8.

[0020] FIG. 5 illustrates how the distal portion 100″ of the plate is tilted at an angle α with respect to the proximal portion 100′ of the plate. The two portions 100′ and 100″ of the plate are joined by an angled portion 105. The angled portion 105 may be substantially perpendicular to the first surface 101. The angled portion 105 may also be substantially perpendicular to the second surface 104. At the angled portion 105, there is a triangular step between the first surfaces 101 and 102. There is a similarly shaped step between the second surfaces 103 and 104. At the proximal portion 100′ of the plate, the second side 103 is substantially parallel to the first side 101. At the distal portion 100″ of the plate, the second side 104 is substantially parallel to the first side 102.

[0021] To correct the misalignment of the foot and further correct the ulnar torsion, a measurement of the angle β is made using a goniometer. Experimental and clinical data provide guidance as to what the plate torsion angle α should be relative to the measured angle β.

[0022] As shown in FIG. 6, the ulna 3 is cut at location 20 into a proximal portion 3′ and a distal portion 3″. Preferably, the incision is straight across and perpendicular to the ulna 3. However, other types of incisions may be used. Preferably, the incision is not near the distal end of the ulna. The incision must be far enough away from the distal end of the radius 2 so that the plate does not interfere with the joint. Plate 100 is attached to the ulna portions 3′ and 3″ in the usual manner. Screws 130 are placed in holes 120. The plate may be clamped to the bone portions to maintain the desired position prior to attachment with the screws. The plate is attached to the flat area of ​​the ulna, on the lateral-caudal aspect of the ulna.

[0023] Having disclosed at least one embodiment of the invention, various adaptations, modifications, additions, and improvements will become readily apparent to those skilled in the art, and all such adaptations, modifications, additions, and improvements are considered a part of the invention, which is limited only by the claims appended hereto.

Claims

1. 1. A plate for adjusting the angle of the medial compartment of the ulna by adjusting the torsion of the ulna, comprising: The plate comprises: a first portion and a second portion; the first portion includes a first side and a second side spaced from and substantially parallel to the first side; the second portion includes a third side and a fourth side spaced from and substantially parallel to the third side; a bridge connecting the first portion to the second portion such that the first and second portions are aligned with the longitudinal axis of the plate; an angle between a first surface of the first portion and a third surface of the second portion; and a plurality of screw holes formed in the plate from the first side to the third side in the first portion and from the second side to the fourth side in the second portion for attaching the plate to bone; Equipped with plate.

2. 2. The plate according to claim 1, The plate is adapted to be attached to the ulna after amputation of the ulna near its distal end. plate.

3. 3. The plate according to claim 2, The first portion is adapted to be attached to a proximal portion of the severed ulna, and the second portion is adapted to be attached to a distal portion of the severed ulna. plate.

4. 2. The plate according to claim 1, The angle between the first surface of the first portion and the third surface of the second portion is selected based on an error in alignment determined by measuring paw twist when the forelimb is held in an extended position and the wrist is hyperextended. plate.

5. 2. The plate according to claim 1, The angle between the first surface of the first portion and the third surface of the second portion is between about 5 degrees and about 60 degrees. plate.

6. 2. The plate according to claim 1, The plate is adapted to be attached to the lateral-caudal aspect of the ulna. plate.

7. 2. The plate according to claim 1, The plate is suitable for the treatment of arthritic conditions of the elbow, namely dysplasia caused by fragmented coronoid process (FCP) or medial compartment disease (MCD). plate.

8. 2. The plate according to claim 1, The plate is adapted to adjust the angle of the medial compartment of the canine ulna. plate.

9. 1. A method for correcting misalignment of the medial compartment by correcting misalignment of the foot, comprising: The method includes the following steps: cutting the ulna near its distal end; and attaching a plate to the ulna at the incision; Including, The plate has a first portion and a second portion angled relative to the first portion. method.

10. 10. The method of claim 9, The plate is a plate according to claim 1. method.

11. 10. A method for correcting misalignment of the medial compartment by correcting the misalignment of the foot as described in claim 9, comprising: The method includes the following steps: determining an angle of deviation of the foot by hyperextending the foot; measuring the difference between the centerline of the metacarpal bone and the mechanical axis of the joint defined by the medial and lateral epicondyles; and selecting a plate to attach to the ulna from a plurality of plates, each plate having a different angle between first and second portions; further comprising: method.

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