ABSTRACT Elbow dysplasia IEDI is a complex disorder that leads to degeneration of the elbow joint through a series of developmental abnormalities. It is the most common cause of elbow pain and lameness in the canine species, particularly large breeds. Diagnosis and treatment of this disorder may be complex, requiring specialist imaging and surgical techniques in order to achieve the best outcomes.

A general understanding of ED is important when providing the nursing care of affected animals.

Anatomy

The canine elbow joint comprises three bones – the radius, ulna and humerus – which must grow together to form a perfect fit in the young animal.

The radius is the main load-bearing bone, whilst the ulna acts as a lever arm for the extensor muscles of the elbow joint. The normal elbow joint facilitates a smooth movement from the ulnar joint surface to the radial joint surface. The medial coronoid process of the ulna sits level with – or slightly below – the surface of the radius.

The main movements of the elbow are flexion and extension, with a small amount of pronation and supination. The elbow is classed as a hinge joint and contains one joint capsule. Normal function of the elbow is crucial for a normal gait.

Elbow dysplasia (ED)

Elbow dysplasia (ED) is the abnormal development of the elbow joint. Different areas within the joint may be affected and this may lead to a combination of primary lesions which may affect the growth of the articular cartilage or the surrounding anatomy.

If the primary lesions are not treated, osteoarthritis will cause further secondary degeneration to occur. Primary lesions include: osteochondritis dissecans (OCD), fragmented coronoid process (FCP), ununited anconeal process (UAP) and incongruity of the elbow joint.

Osteochondritis dissecans (OCD)

Osteochondritis dissecans is a joint condition that occurs when the blood supply to the subchondral bone and cartilage is impared. This causes the bone tissue to die and breakdown, damaging the cartilage.

Instead of being attached to the bone it covers, the cartilage separates or cracks. A loose flap of cartilage may form, or a fragment of cartilage may become detached within the joint. This results in pain and further joint damage.

Fragmented coronoid process (FCP)

This is a condition in which the medial coronoid process of the ulna fractures. It may be caused by OCD of the coronoid process or abnormal mechanical stress on the coronoid process.

Ununited anconeal process (UAP)

This is the failure of the anconeal process to unite with the proximal ulnar metaphysis by the time the dog is five to six months old.

Incongruity of the elbow joint

This is a combination of misalignment and malformation of the elbow joint. Uneven proximal growth between the radius and ulna may lead to cartilage damage in the humero-ulnar compartment caused by abnormal load bearing of the joint.

Diagnosis

Elbow dysplasia can be diagnosed by means of clinical signs, radiography, computed tomography (Figure 1), arthroscopy, magnetic resonance imaging and joint fluid analysis. 

Figure 1: CT scan showing fragmentation of the medial coronoid process

Treatment

Conservative treatment

Non-surgical treatment of ED may be used in less severe cases, where there is little evidence of pathology and clinical signs are minimal. Conservative treatment includes weight reduction, physiotherapy, hydrotherapy, exercise restriction and medication to provide analgesia and control inflammation.

Chondroprotectants glucosamine and chondroitin, may reduce cartilage damage and also reduce pain. Their efficacy, however, is still unproven.

Surgical options

. Arthroscopic fragment removal Isolated fragments of the coronoid process of the ulna are removed with an arthroscope via keyhole surgery (Figure 2). . Subtotal coronoid ostectomy ISCOl Another keyhole procedure used to remove the part of the coronoid process of the ulna that is affected by microscopic stress fracturing.

Figure 2: MRI scan showing use of a graft into the elbow

•   Proximal ulnar osteotomy IPUOI This procedure is used to correct an incongruity affecting the elbow joint. The ulna is incised beneath the elbow joint to allow a more synonymous joint to form.

•   Biceps ulnar release procedure This arthroscopic procedure involves incising the section of the biceps tendon that produces excessive force of the radial head against the coronoid process.

•   Sliding humeral osteotomy ISHOl Surgical repositioning of the humerus using a specialised bone plate and screws. This transfers load bearing to the healthier lateral joint and away from the damaged medial aspect of the joint. This procedure is used: (i) in dogs with severe ED; (ii) where there is concurrent advanced osteoarthritis; and (iii) where cartilage damage is so advanced that cartilage may be absent on the medial aspect, but is still relatively healthy on the lateral aspect of the joint.

•   Osteochondral resurfacing

This procedure facilitates resurfacing of the articular cartilage and is a treatment used for OCD. Osteochondral autograft transfer (OAT) involves the removal of a plug of cartilage and bone from a non¬load-bearing area of the patients stifle which is then inserted into the affected area of the elbow. Synthetic osteochondral transfer (SOT) involves the use of a synthetic implant.

•   Anconeal process reattachment/ removal

Anconeal process surgery is used to treat dogs with a UAP where the anconeal process is reunited surgically. This is performed using a specialised screw alongside a proximal ulnar osteotomy (PUO) to allow the proximal ulna to be placed in a more appropriate position in relation to the humerus. In more severe cases involving a change in shape, the anconeal process may be completely excised.

•   Canine unicompartmental elbow replacement ICUEl

This surgical procedure is an alternative to an SHO. The uni-compartmental replacement is a minimally invasive option for patients whose lesion is isolated to the medial compartment. It involves replacing the damaged
section of cartilage with a prosthesis (Figure 3).

Figure 3: Postoperative image of a canine unicompartmental elbow replacement

•   Total elbow replacement ITERI This surgery is used when the ED and concurrent osteoarthritis is so severe that this is the only surgical option available. The whole joint is replaced with a prosthesis. Often these have to be custom made for canine patients.

Fitzpatrick Referrals have pioneered and refined many of the techniques described above.

 

Postoperative nursing

Postoperative nursing includes continuous patient monitoring, management of pain, wounds/bandages, fluid therapy, medication, nutrition and physiotherapy (including range of movement, weight-bearing exercises and assisted walking exercises as guided by the veterinary surgeon).

Summary

Elbow dysplasia is a complex disease which may be caused by genetic, developmental or nutritional factors. Risk factors include rapid growth and weight gain, inappropriate levels of exercise and a high calorie diet. Measures to limit future cases of ED may be achieved by preventing the breeding of affected individuals and the veterinary nurse can be instrumental in educating owners in this respect.

Author

Sian Norris BScAnSci(Hons) RVN Dip Animal Physiotherapy

Sian graduated from the University of Reading in 2001 with a Degree in Animal Science. During her spare time at university, she worked as a veterinary nurse, and after graduating went on to gain her qualification as a Registered Veterinary Nurse in 2004. Sian has most recently completed a Diploma in Animal Physiotherapy and currently works as a ward rehabilitation co-ordinator at an ofthopaedic referral centre in Surrey

To cite this article use either

DOI: 10.1111/j.2045-0648.2012.00213.x or Veterinary Nursing Journal Vol 27 pp 331-332

Useful references

•   http://www.fitzpatrickreferrals.co.uk/our- services/surgery/conditions/elbow-dyslapsia

•   http://www.bva.co.uk/public/documents/ chs_elbow.pdf

•   BOCKSTAHLER. B„ LEVINE, D„ MILLIS. D. L. and WANDREY. S O (2004) Essential facts of physiotherapy in dogs and cats: rehabilitation and pain management: a reference guide with DVD Babenhausen, B. E. Vet Verlag

•   GROSS. D M [2002] Canine Physical Therapy. Orthopaedic Physical Therapy. Connecticut: Wizard of Paws

•   MILLIS. D. L„ LEVINE. D. and TAYLOR. R A. [2004] Canine Rehabilitation and Physical Therapy. St. Louis. MO. Saunders.

 

• VOL 27 • September 2012 • Veterinary Nursing Journal