Elbow dysplasia (Proceedings)

The goal of nonsurgical and/or surgical management of the developmental abnormalities of the elbow is to slow the progression OA in the joint and reduce lameness in the patient. The specifics of surgical management are dependent upon diagnosis. For the purposes of this abstract I'll focus on fragmentation of the medial coronoid process (FCP) and osteochondrosis (OCD) of the medial aspect of the humeral condyle. A united anconeal process (UAP) can be treated by removal of the process or internal stabilization of the process but empirically is best treated via a proximal ulnar osteotomy with or without supplemental internal fixation with an interfragmentary lag screw.

Historically, both FCP and OCD are treated by removal of the fragment, debridement of loose cartilage ends adjacent to the primary lesion and, when indicated, microfracture of eburnated bone via arthrotomy or arthroscopy. Both can be associated with kissing lesions on the opposing cartilaginous surface, so a through exploratory of the joint is required. Many have hypothesized that elbow joint incongruency either predisposes dogs to a FCP or persists in conjunction with it. This hypothesis has led some surgeons to incorporate a dynamic proximal ulnar osteotomy or radial head lengthening as a component of treatment. While these are intriguing concepts essentially no peer-reviewed literature exists to support or refute them.

Nonsurgical and surgical management of developmental conditions of the elbow joint frequently leads to unsatisfactory results. In fact, most literature strongly suggests that surgery provides little, if any, advantage to patient prognosis when compared to medical management. Huibregtse et al. studied 22 dogs with forelimb lameness caused by a FCP and provided evidence that elbow OA progressed radiographically in dogs following nonsurgical or surgical treatment. In addition, they performed force plate gait analysis on the dogs and found that there was no difference in limb function between groups. They also found that owners reported a recurrence of lameness in 78% of dogs treated without and 69% of dogs treated with surgery. Mean follow-up time was not reported in this retrospective study. Bouck et. al. studied 19 dogs diagnosed with FCP and/or OCD that were treated medically or surgically using physical, radiographic and force plate gait evaluations and found similar results. One distinct advantage of this study was that is was prospective with a one year follow-up time. They found that regardless of treatment, OA progressed radiographically and range of motion decreased over time. Using force plate gait evaluations they determined that dogs in both groups improved but there was no difference in the amount of improvement between treatment groups. The mean peak vertical force in the affected limb of dogs increased from 40 to 45% of body weight in both groups.

Read et al. studied the largest groups of dogs; reporting on 130 cases of FCP in 109 dogs. This retrospective study focused on the opinion of the dog's owner to report on the degree of lameness and activity before and after treatment. In this study 62 cases were managed nonsurgically and 68 were managed surgically. They found that the degree of lameness improved to some degree in 59% of dogs, regardless of treatment. Lameness, however, persisted in 75.9% of all dogs studied. They also attempted to correlate the degree of lameness at initial presentation to post-treatment outcome, reporting that dogs with mild lameness are less likely to benefit from surgery than dogs with moderate or severe lameness. Tobias et al. performed a long-term evaluation of 35 dogs that had surgery for FCP. Their evaluation included an owner questionnaire, physical exam, and radiographic exam. They concluded that surgical approach and age of patient at the time of surgery did not affect prognosis. Perhaps more interesting, however, was the fact that nearly 65% of dogs still had lameness, 80% had joint pain, and over 95% had joint thickening and a reduced range of motion at follow-up examination. In addition, OA significantly increased in 100% of the cases.

Caplan et al. provided additional evidence that, regardless of treatment, OA progresses in dogs with developmental disorders of the elbow. They studied the progression of OA using radiographic examinations in 50 dogs that were treated for lameness because of a FCP. Twenty-four dogs were treated non-surgically, 26 were treated surgically. All dogs were had initial and follow-up radiographic examination performed at the Veterinary Teaching Hospital at Iowa State University. Radiographic views evaluated were a craniocaudal, lateral, and flexed lateral. All radiographs were covered such that the two radiologists would not know the signalment of the patient, or if the radiograph was an initial or follow-up radiograph. The radiographs were evaluated independently and scored for degree of OA based on the grading system developed by the International Elbow Working Group. They found that OA progressed in 100% of cases. In addition, they determined that the progression of OA was the same regardless of treatment. A recent report that compared outcome in dogs with FCP after surgery via arthrotomy or arthroscopy found that dogs that had arthroscopic surgery to treat their disease had a better outcome.

More recently, an improved success rate using arthroscopy has been reported. However, the outcome measures were subjectively based so enthusiasm should be tempered. Additional surgeries to treat this problem (alone or in conjunction with debridement) include the sliding humeral osteotomy, radial head lengthening and proximal ulnar osteotomy. To date, none have good scientific evidence that they will change the disease progression.

Surgical management for dogs with established OA from elbow dysplasia

Current surgical treatment alternatives for dogs with moderate to severe elbow OA include removing loose bodies and osteophytes from the joint, sliding humeral osteotomy, arthrodesis and total elbow replacement. In a clinical report, one dog with severe elbow OA had surgery to remove fragmented medial coronoid processes and a fractured anconeal process; this dog returned to near normal function after surgery. This case may be the exception, however, because the dog became acutely lame because of an intra-articular fracture and the case was complicated by the OA. Bardet reported that dogs treated with arthroscopic debridement of the elbow joint have a favorable prognosis, increased range of motion and a reduction in lameness. Specifically, he removed joint osteophytes, synovial proliferation, chondromalacic cartilage and loose fragments. Dogs were also aggressively treated with analgesic medication and cryotherapy for 10 days after surgery. Although this clinical report is encouraging, prospective patient evaluation and objective evaluation of outcome is needed. Recent research addressing the sliding humeral osteotomy has demonstrated that it will reduce loads at the medial compartment of the joint. This procedure, in effect, is designed to mimic the proximal tibia osteotomy that is performed in people with medial compartment disease of the knee. Investigators at UC Davis are currently performing a clinical trial in dogs with mild to moderate elbow OA isolated to the medial compartment of the joint. DeHann et al. retrospectively investigated results after arthrodesis of the elbow and found that although pain in the joint was alleviated, function of the limb was limited.

Total elbow arthroplasty has been reported in the dog. Lewis discussed his experiences with the use of a constrained (hinge-like) implant and although he stated there were some successful outcomes he concluded that because of a high complication rate the system needed to be redesigned. Phil Vasseur designed a nonconstrained system and tested it in three dogs with naturally occurring elbow OA. The dogs in that study had poor short-term and long-term results and the project was abandoned. Conzemius et al. published the first peer-reviewed manuscript addressing total elbow replacement in the dog. In that first report elbow replacement was performed in six normal, large breed dogs. Although several potential problems were identified with the implant design and the surgical technique, one year after surgery, limb function as measured by force platform gait analysis had returned to normal in three dogs. Following changes in the two implant system and the surgical technique total elbow replacement was performed in 20 consecutive cases. Each dog had severe, daily lameness from chronic elbow osteoarthritis that was unresponsive to medical management. In that report, one year after surgery 16 of 20 dogs had significantly improved limb function. Serious complications occurred in 3 dogs (infection or lateral luxation) and one dog did not improve. This implant system has continued to be used and improved with a new cutting guide system that has been available for the past 2 years. Competitive systems have also been used clinically. Unfortunately, none have survived the test of time. However, it is important that we continue to make improvements that increase patient success and recovery rates. The greatest disadvantage to elbow replacement, as with hip replacement, is that a serious complication can result in a second surgery that requires removal of the implant system. In the elbow, this leaves the surgeon with few options— generally arthrodesis but amputation has also occurred following severe complications (neurogenic injury or untreatable infection).