Advances in External Skeletal Fixation

1. Canine Elbow Dysplasia In Newfoundlands Advances in External Skeletal Fixation Robert J. McCarthy, DVM, MS, DACVS

2. CED is the #1 cause of forelimb lameness in Newfoundlands, as well as in several other large breed dogs Canine elbow dysplasia (CED) refers to a collection of developmental diseases of the elbow, specifically ununited anconeal process (UAP), fragmented coronoid process (FCP), and distal humeral osteochondritis dissecans (OCD) FCP is by far the most common problem in Newfoundlands Overview

3. Overview: Anatomy of the elbow • The elbow is essentially a hinge, with three bones (humerus, radius and ulna) forming the joint

4. Overview: Anatomy of the elbow Anconeal process Coronoid process

5. Overview: Ununited anconeal process UAP 32 week old Newfoundland

6. Overview: Elbow OCD 8 mo old Newfoundland

7. Overview: Fragmented coronoid process 6 mo old Newfoundland

8. Essentially all dogs with untreated CED will develop progressive osteoarthritis and lameness Overview

9. Intermittent, persistent or shifting leg lameness Stiff, choppy, stilted forelimb gait Pocket of fluid at outside of the elbow Panosteitis is very rare in Newfoundlands! Overview: Clinical signs

10. Overview: Clinical signs Age of first clinical sign in dogs with CED

11. UAP and OCD are easily diagnosed on routine radiographs Overview: Diagnosis

12. FCP is very difficult to see on routine radiographs Overview: Diagnosis

13. FCP is very difficult to see on routine radiographs Overview: Diagnosis

14. Computed tomography will diagnose this problem Overview: Diagnosis

15. Arthroscopy can be used to visualize the problem Overview: Diagnosis

16. Elbow incongruity (EI) is believed to be the underlying cause of all manifestations of CED, and may exist alone It has been difficult to prove a single anatomic defect to explain all manifestations of CED Overview: Anatomic defect

17. OCD UAP FCP Overview: Anatomic defect Classic research by Alida Wind postulated abnormal shape of the ulna caused CED Normal Canine elbow dysplasia

18. Compared shape of the ulna in a breed with a high incidence of CED (Rottweiler) with that of low incidence breed (Greyhound) Overview: Anatomic defect Collins KE, Cross AR, Lewis DD, et.al. A comparison of the radius of curvature of the ulnar trochlear notch of rottweilers and greyhounds using three dimensional digitization. Proc 9th Annual Amer Coll Vet SurgSymposium 1999; 4.

19. Rottweiler Greyhound Overview: Anatomic defect Both Greyhounds and Rottweilers have an elliptical, rather than circular trochlear notch, and Greyhound is actually more narrow

20. A second common theory implicates uneven growth between the radius and ulna FCP or OCD UAP Overview: Anatomic defect

21. Compared tracings of lateral radiographic projections in dogs with unilateral UAP Overview: Anatomic defect Sjostrom L, Kasstrom H, Kallberg M. Ununited anconeal process in the dog. Pathogenesis and treatment by osteotomy of the ulna. VCOT 1995; 8:170-176.

22. 15/17 elbows traced had a relatively long radius on the UAP affected side Overview: Anatomic defect Tracings obtained from a dog with unilateral UAP Brown = UAP Gray = Normal leg

23. Created a short radius in normal cadaver dogs, and found intraarticular contact pattern was altered to stress the medial coronoid process, similar to cases with FCP FCP or OCD Overview: Anatomic defect Preston CA, Schulz KS, Kass PH. Effect of radial shortening and subsequent corrective ulnar ostectomy on joint contact patterns in a canine elbow model. Proc 27th Annual Vet Ortho Soc 2000; 41.

24. Whatever the cause of canine elbow dysplasia, it is important to remember that simple removal of a UAP or FCP, or curettage of an OCD lesion will not resolve the underlying problem Overview: Anatomic defect

25. 33% of Newfoundlands in Norway diagnosed with CED 57% of Rottweilers in Australia have XR signs of CED 30-50% of Bernese Mountain Dogs are affected Elbow Dysplasia: Incidence of the problem

26. 57% of Rottweilers in Australia had XR signs, but only 15% developed clinical signs If +XR at 6mo, 50% chance of developing clinical signs Grade 2 CED at 12 month significantly correlated with clinical signs of disease Elbow Dysplasia: Clinical vs. XR signs Osteophytes None 0 <2mm 1 2-5mm 2 >5mm 3

27. UAP, OCD, and FCP are inherited, independent polygenic traits (Padgett) Incidence in progeny more likely with increasing severity of arthritis in sires and dams Maternal effect has been demonstrated in Labrador retrievers and Rottweilers Elbow Dysplasia: Genetics and breeding

28. Prevalence of elbow dysplasia can be decreased with selective breeding Elbow Dysplasia: Genetics and breeding

29. Dogs with CED should NOT be bred Dogs producing offspring with CED should NOT be bred If possible, “NORMAL” first degree relatives of dogs with CED should NOT be bred Elbow Dysplasia: Genetics and breeding

30. Medical management should involve a “total health” plan Moderate exercise Control of body weight Anti-inflammatory pain medication (NSAID’s) Disease modifying osteoarthritis drugs (DMOA’s) Elbow dysplasia: Medical therapy

31. Conservative Medical Therapy Anti-inflammatory pain medication

32. Highly specific COX-2 inhibitor deracoxib (deramaxxR) has recently been approved for veterinary use Deracoxib Conservative Medical Therapy

33. Conservative Medical Therapy Disease modifying osteoarthritis drugs

34. Found that 84% of tested products did not meet label claim with contents raging from 0% to 115% of the label claim Some products had forms of chondroitin sulfate which were not absorbed Conservative Medical Therapy Adebowale A, Cox D, Liang Z, Eddington N. Analysis of glucosamine and chondroitin sulfate content in marketed products and the Caco-2 permeability of chondroitin sulfate raw materials. JANA 3(1): 37-44, 2000

35. Conservative Medical Therapy % Label Claim Price per daily dose (1200mg) chondroitin

36. Conventional therapy involves removal, but arthritis is inevitable Surgical Therapy: Ununited Anconeal Process

37. Screw fixation has been described with success, but is technically demanding, and failure may be common Surgical Therapy: Ununited Anconeal Process Fox SM et.al. Ununited anconeal process: lag-screw fixation. JAAHA 1996

38. Surgical Therapy: Ununited Anconeal Process

39. Ulnar osteotomy (cutting the ulna) has recently been advocated This procedure relieves stress on the UAP, allowing it to heal spontaneously Surgical Therapy: Ununited Anconeal Process

40. Surgical Therapy: Ununited Anconeal Process UAP immediate postop UAP 8 weeks postop

41. Debate exists regarding whether surgical therapy of any type is beneficial Surgical Therapy: Fragmented coronoid process

42. 22 dogs received either surgery or NSAID/rest Surgery entailed removal of the FCP 11 dogs available for follow-up Examined radiographic scores , mean force plate values, elbow ROM, and owner questionnaire Surgical Therapy: Fragmented coronoid process Huibregtse, BA, Johnson AL, Muhlbauer MC. The effect of treatment of fragmented coronoid process on the development of osteoarthritis of the elbow. J Am An Hosp Assoc 1994; 30:190-195.

43. Most owners felt that there was improvement in their pet with or without surgery Surgical Therapy: Fragmented coronoid process

44. 19 dogs with either FCP or OCD of the elbow received either surgery or pentosan polysulphate Examined force plate values for 9 months Surgical Therapy: Fragmented coronoid process Bouck G, Miller C, Taves C. A comparison of surgical and medical treatment of fragmented coronoid process and osteochondritis dissecans of the canine elbow. VCOT 1995; 4:177-183.

45. Surgical Therapy: Fragmented coronoid process

46. Studies that investigate surgical vs. medical management of FCP are based on small numbers of cases, broad inclusion criteria, and have been usually retrospective in nature Studies have not evaluated medical + surgical therapy to either therapy alone Traditional surgery is traumatic!! Surgical Therapy: Fragmented coronoid process

47. Arthroscopic removal of FCP has been developed over the last several years Arthroscopic evaluation allows improved visualization and access to intraarticular structures, with minimal patient morbidity Tufts University School of Medicine has performed over 100 arthroscopic procedures for FCP Surgical Therapy: Fragmented coronoid process

48. Surgical Therapy: Fragmented coronoid process

49. 32 dogs (62 elbows) had arthroscopic procedure for CED Surgical removal of fragments with minimal trauma possible in all cases Return to preop lameness status within 1 week Improvement in lameness status within 4 weeks in most dogs Improved results if before development of severe OA Surgical Therapy: Fragmented coronoid process Beale BS. Arthroscopic treatment of elbow dysplasia in dogs. Proc 26th Conf Vet Ortho Soc 1999; 4.

50. Surgical therapy involves removal of the flap, and curettage of the defect Curettage is easily performed arthroscopically which should be considered the procedure of choice Very limited case numbers prohibit determination of prognosis Surgical Therapy: Elbow OCD