ARTHRODESIS OF THE SHOULDER, ELBOW, AND CARPUS
CHARLES D. NEWTON
- Arthrodesis of the Shoulder
Arthrodesis of the Elbow
Arthrodesis of the Carpus
ARTHRODESIS OF THE SHOULDER
Shoulder arthrodesis is not commonly performed. When necessary, however, it is used to correct severe degenerative arthritis secondary to fracture, osteochondritis dissecans, or chronic shoulder luxation. Occasionally, in the presence of a severe articular fracture, arthrodesis may be used as a primary procedure if fracture repair is not possible.
The shoulder can be adequately arthrodesed using plate and screw fixation. The surgical approach is made through a lateral exposure of the shoulder and complete elevation of the acromial head of the deltoid muscle at its humeral attachment. Tenotomies of the infraspinatus muscle and teres minor muscle are necessary. The supraspinatus muscle is either elevated and retracted or detached by means of lateral tubercle osteotomy. This exposure will allow complete visualization of the shoulder joint.
The apposing cartilaginous surfaces are debrided to the depth of bleeding subchondral bone. If desired, a saw may be used to cut flat apposing surfaces. The approximate angle of the arthrodesis must be established and may be fixed temporarily with a Kirschner wire. The plate is contoured to lie over the lateral surface of the scapula, cranial to the scapular spine, and on the cranial or craniolateral humeral surface. This requires bending and torquing the plate.
Following bending, the plate is applied to the scapula. The arthrodesis site should be packed with autogenous cancellous bone, usually harvested from the ipsilateral ilial wing. Following grafting, the plate is attached to the proximal humerus. In very large dogs, additional interfragmentary screws may be placed across the site of arthrodesis (Fig. 46-1).
PIN AND WIRE TECHNIQUE
Arthrodesis may also be accomplished using pin and wire tension band techniques. Following joint debridement and cancellous grafting, two pins are driven from the cranial proximal humerus obliquely across the arthrodesis site into the scapular neck. Likewise, two pins are driven from the cranial scapular neck obliquely into the humeral head. A figure- of- eight or tension band wire is applied around the pins over the cranial surface of the shoulder.
The shoulder may require additional external fixation to ensure arthrodesis. This is accomplished best in a shoulder spica. The spica may be plaster, an adapted SchroederThomas splint, or an adapted Robert Jones dressing. The external fixation should be maintained for 6 to 8 weeks or until there is radiographic evidence of bony union.
ARTHRODESIS OF THE ELBOW
Arthrodesis of the elbow is necessitated by severe degenerative arthritis secondary to primary fracture of the elbow, ununited anconeal process, ununited coronoid processes, osteochondritis dissecans, or traumatic recurrent luxation. Premature closure of the distal ulnar or radial epiphyseal plate may result in sufficient elbow subluxation that arthrodesis is required to correct the instability or to treat secondary degenerative joint disease.
PLATE AND SCREW FIXATION
Surgical exposure for elbow arthrodesis is accomplished best by means of olecranon osteotomy to expose the caudal surface of the distal humerus.(1,5,6) Further muscular dissection allows for a complete visualization of the joint surfaces and the proximal caudal ulna.
Opposing cartilaginous surfaces must be debrided to the depth of bleeding subchondral bone. It is essential that all cartilage be removed from the humeral condyles, the semilunar notch, and the entire radial head. If possible the collateral ligaments should be protected, since they will help maintain positioning and some degree of stability during the procedure.
FIG. 46-1 One method of plate placement for arthrodesis of the shoulder.
The elbow is positioned at the desired angle and fixed temporarily with a Kirschner wire. An eight- or tenhole plate should be contoured to the caudal surface of the joint. The plate should be positioned so that at least three screws seat completely into the humerus and three into the ulna. Following plate bending, the plate is attached to the humeral fragment. The transfixation pin is removed and the opposing surfaces packed with autogenous cancellous bone. It is important to pack bone over the cranial surface of the joint. Following grafting, the plate is attached to the ulnar surface. The central holes in the plate should allow for the placement of interfragmentary compression between the proximal ulnar fragment and the humeral condyles. If needed, additional interfragmentary screws may be placed across the arthrodesis site.
Following plate placement, the olecranon must be retracted to preserve the triceps attachment. The olecranon is usually attached with a single screw to the lateral surface of the arthrodesis site (Fig. 46-2 and 46-3).
INTERFRAGMENTARY SCREW FIXATION
Arthrodesis using only interfragmentary screws has been suggested by one author(7) following the steps of routine arthrodesis outlined above. After placement of the temporary fixation wire, one or more interfragmentary screws are placed through the ulna into one or both of the humeral condyles. Cancellous screws are considered superior to cortical screws for use in this situation. An additional 18-gauge tension band wire is attached between the olecranon and humerus to protect the screws.
This technique has met with only moderate success, since screw loosening or breakage can occur. Use of this technique should be limited primarily to cats and dogs under 20 pounds.
Following arthrodesis the limb must be immobilized in a long-leg cast or splint for 6 to 8 weeks. Preferably the device will also immobilize the shoulder joint. The external immobilization should not be removed until there is radiographic evidence of bony union.
Elbow arthrodesis, even when completely successful, may lead to other problems. With the motion of the elbow gone, the shoulder and carpus are subjected to much greater forces when the animal walks. Most animals will walk by circumducting the shoulder to position the limb. This will place the limb on the ground in full carpal extension and usually in much more shoulder extension than normal. Because the useful range of motion in the shoulder and carpus has been changed, these joints are prone to strain, sprain, or degenerative arthritis. Fracture above or below the internal fixation is also a possibility.
Bilateral elbow arthrodesis makes it virtually impossible for an animal to rise, lie down, or negotiate steps. If placed on its feet, the animal is capable of limited ambulation but little else. Therefore, bilateral elbow arthrodesis is not advisable.
FIG. 46-2 Plate placement for arthrodesis of the elbow.
FIG. 46-3 Medial-lateral (A) and cranial-caudal (B) radiographs demonstrate fusion of a canine elbow 10 months postoperatively, following plate and screw fixation.
ARTHRODESIS OF THE CARPUS
Carpal arthrodesis is often required following severe internal derangement resulting in dislocation. Generally all supporting ligaments have been torn and nonsurgical methods of repair prove unsuccessful. Subluxation or dislocation may involve all three levels of the carpal joint and require pancarpal arthrodesis. If injury involves only the antebrachiocarpal joint or the middle carpal joint or the carpometacarpal joint, only the affected joint is arthrodesed.
Flexion deformities resulting from radial nerve paralysis may be treated by pancarpal arthrodesis if the level of paralysis is below the elbow.(3) Carpal arthrodesis is also used to treat end-stage degenerative joint disease resulting from fracture or sepsis.
PLATE AND SCREW FIXATION
Surgical exposure is accomplished using a cranial incision from midradius and ulna, across the carpus to midmetacarpus. The accessory cephalic vein and the extensor tendons must be mobilized and retracted. All three joints of the carpus are opened transversely to expose the articular surfaces. The articular cartilage is debrided from all surfaces to the depth of bleeding subchondral bone. The carpus is arthrodesed either straight (0¡ flexion) or in 5¡ of extension.(8) An eight-hole plate should be prepared for application, either bent, with 5¡ of dorsiflexion, or unbent, depending on the surgeon's preference. The plate is applied first to the cranial surface of the radius and positioned so that one screw (usually the fourth) can be placed into the radial carpal bone. After radial attachment, the arthrodesis sites are filled with autogenous cancellous bone. It is important to place bone grafts over the caudal surface of the joint. Finally the plate is positioned over and attached to the third metacarpal bone. The central holes of the plate, which lie over the carpus, are the last to be filled with screws (Figs. 46-4 and 46-5).
SLIDING CORTICAL BONE GRAFT TECHNIQUE
A technique that is very similar to plate and screw fixation has been described by Wind.(10) Fixation is achieved using a cortical bone graft instead of a bone plate. The graft is harvested from the cranial surface of the radius. After preparing the carpus for arthrodesis, the graft is moved distally from the donor site and slid across the carpus.
FIG. 46-4 Plate placement for pancarpal arthrodesis.
FIG. 46-5 Medial-lateral (A) and cranial-caudal (B) radiographs demonstrate pancarpal fusion in a dog 6 months postoperatively, following plate and screw fixation.
The graft is then attached using bone screws. The cortical graft must be long enough to allow at least two screws to be placed in the distal radius and at least two in the third metacarpal bone.
Transfixation pins have been used very successfully in carpal arthrodesis. Following joint debridement and graft placement, two or more Steinmann pins are placed through the joint surfaces. The pins should be placed as widely apart as possible to prevent rotational instability. Usually one is introduced from the medial side of the base of metacarpal II and angled proximally and laterally into the distal radius; the second pin begins lateral to metacarpal bone V and angles proximally and medially through the carpus, ending in the medial side of the radius (Fig. 46-6).
Kirschner-Ehmer devices or similar devices may be used for carpal arthrodesis. Following joint debridement and cancerous grafting, at least two pins are introduced through the distal radius medial to lateral; similarly two pins are placed through the metacarpal bones. All pins are connected externally and held rigidly in place. Fullpin Kirschners are far superior to half-pin Kirschners for this function.
Antebrachiocarpal arthrodesis is indicated if only the antebrachiocarpal joint is involved with pathology. Its advantage over pancarpal arthrodesis is that some motion (15¡-25¡) will be preserved by not arthrodesing the middle carpal or carpometacarpal joints.
FIG. 46-6 Transfixation pin placement for pancarpal arthrodesis.
PLATE AND SCREW FIXATION
Straight plates are not useful for this surgery because they allow only one screw to be placed into the radial carpal bone. For this reason, "T" plates are used. They allow for placement of three or four screws into the radial and ulnar carpal bones and a similar number into the radial shaft. The "T" plate is usually applied with the antebrachiocarpal joint in 0¡ of flexion; however, 5¡ of extension is also acceptable.
The "T" plate is first attached to the radial and ulnal carpal bones. It is attached to the radius following grafting of the arthrodesis site (Figs. 46-7 and 46-8).
Antebrachiocarpal arthrodesis may be accomplished by transfixation of the joint using grafted pins. The joint is prepared and grafted following routine arthrodesis procedures. Pins are introduced from distally and laterally through the ulnar carpal bone medially and distally through the radial carpal bone and through the joint to seat in the radius. It is imperative that the pins do not damage or encroach on the middle carpal joint, since loss of motion will result.
MIDDLE CARPAL-CARPOMETACARPAL ARTHRODESIS
Middle carpal-carpometacarpal arthrodesis is required if one or both of the distal two joints of the carpus are damaged. Its obvious advantage is that antebrachiocarpal motion can be preserved. Animals with middle carpal and carpometacarpal arthrodesis have nearly a normal range of motion in the carpus because of a normal antebrachiocarpal joint.
Fixation may be accomplished with two or more transfixation pins. Following routine joint preparation, pins are introduced beginning proximally and laterally through the ulnar carpal bone and across the joints, ending in the base of metacarpal II. The other pin begins proximally and medially through the radial carpal bone and courses through the joints to seat in the base of metacarpal V. Extreme care must be taken to ensure that no damage is done to the antebrachiocarpal joint or to the collateral ligaments during pin placement or pin cutting (Fig. 46-9).
Following any type of carpal arthrodesis, external fixation is necessary. A long-leg cast of plaster or fiberglass works well The cast must remain in place for 6 to 8 weeks or until there is radiographic evidence of fusion.
FIG. 46-7 "T" plate placement for antebrachiocarpal arthrodesis.
FIG. 46-8 Medial-lateral (A) and cranial-caudal (B) radiographs demonstrate antebrachiocarpal fusion in a dog 8 months postoperatively following "T" plate fixation.
FIG. 46-9 Transfixation pin placement for middle carpal-carpometacarpal arthrodesis.
Complications in carpal arthrodesis are rare, assuming that fusion occurs. If the arthrodesis fails, it probably reflects inadequate debridement, inadequate grafting, inadequate internal fixation, inadequate external fixation, or a combination of the above.
Once arthrodesis is accomplished, animals do well. Occasionally the elbow comes under more stress and may develop degenerative joint disease; however, this is rare.
Bilateral carpal arthrodesis is a feasible procedure if needed. Animals are capable of walking and performing well as pets.Dogs or cats with bilateral middle carpal carpometacarpal arthrodesis will appear normal and function normally.
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2. Denny HR: Arthrodesis of the carpus. In Denny HR (ed): A Guide to Canine Orthopaedic Surgery, pp 121-122. Oxford, Blackwell Scientific Publishing Company, 1980
3. Frost WW, Lumb WV: Radiocarpal arthrodesis: A surgical approach to brachial paralysis. J Am Vet Med Assoc 149; 1073, 1966
4. Leeds EB: Carpal arthrodesis for overextension of the carpus. Canine Pract 4:32, 1978
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9. Sexton RL, Hurov LI: Repair of carpometacarpal instability after radiocarpal arthrodesis in a dog. J Am Vet Med Assoc 172:1186, 1978
10. Wind A: Surgical diseases of the carpal joint and methods of treatment. In Bojrab MJ (ed): Current Techniques in Small Animal Surgery, pp 54N548. Philadelphia, Lea & Febiger, 1975