Acquired traumatic conditions of the elbow include:

 Condylar fractures of the humerus

 Medial epicondylar fracture of the humerus

 Fractures of the proximal ulna and olecranon

 Fracture of the anconeal process

 Fracture of the radial head

 Luxation

 Ulnar fracture with radial head luxation (Monteggia fracture)

 Luxation of radial head in cats

 Avulsion and ruptures of the tendon of insertion of the triceps muscles

Diagnosis of traumatic elbow conditions is usually straight forward and is based on observation of the patient, gentle palpation of the elbow and radiographic examination. Diagnosis can usually be confirmed from orthogonal (mediolateral and craniocaudal) views of the elbows. Oblique craniocaudal views maybe necessary to confirm a condylar fissure in cases with incomplete ossification of the humeral condyle (IOHC).

Condylar fractures of the humerus

Condylar fractures can be broadly classified as lateral, medial or intercondylar. The relative incidence of these categories, given below, is taken from reviews of 133 cases (Denny, 1983) and of 39 cases (Butterworth, 1992), respectively. Condylar fractures usually result from a violent upward stress transmitted through the head of the radius onto the humeral trochlea. The lateral component of the humeral condyle appears to have the weakest attachment to the humeral shaft and fractures most frequently (56 and 57% of cases, respectively). In the face of even greater stress the medial part of the condyle is also sheared off giving rise to an intercondylar ('Y' or 'T') fracture (33 and 40 % of cases, respectively). Solitary fractures of the medial condyle occurred far less frequently (11 and 3 % of cases, respectively).

Spaniel breeds of dogs appear to be more prone to condylar fractures. Incomplete ossification of the humeral condyle (IOHC), predisposing to fracture, has been demonstrated predominantly in spaniels (e.g., American Cocker, Springer, Brittany Spaniel and Cavalier King Charles), it has also been reported in the Labrador Retriever, Rottweiler and Pug. It has been suggested in the Cocker Spaniel that incomplete ossification of the humeral condyle may be a genetic disease with a recessive mode of inheritance (Marcellin-Little & others, 1994), In the UK the Springer Spaniel is the most commonly affected breed (Butterworth and Innes 2001).

IOHC is characterised by chronic intermittent lameness varying from mild to non weight bearing. There is pain on elbow extension.

A radiolucent line or fissure may be seen in the intercondylar region of the humerus on a craniocaudal radiograph of the elbow. Further radiographs with 15 degrees of craniomedial or craniolateral rotation increases the chances of seeing the fissure. CT is more sensitive for detecting IOHC. Arthroscopic examination can on occasions also demonstrate a fissure in the articular cartilage.

Placement of a transcondylar lag screw is recommended as a prophylactic measure in view of the high risk of condylar fractures in dogs with IOHC (Marcellin-Little et al 1994). Either a lag or position screw can be used. The largest screw possible should be used to minimise risk of implant failure--(4.5 mm cortical screw in average size Springer Spaniel).

Falls, jumping and sudden turns at exercise are the most common causes of lateral or medial condylar fractures. Intercondylar fractures are more likely to be caused in road traffic accidents. Lateral and medial condylar fractures affect predominantly immature dogs (peak age incidence at 4 months) whilst intercondylar fractures tend to be more evenly distributed between skeletally mature and immature dogs.

Radiographic diagnosis is straight forward however it is worth obtaining radiographs of the contralateral elbow in those breeds with a known predisposition to IOHC.

Condylar fractures are articular fractures and as such require surgical treatment with accurate anatomical reduction and rigid internal fixation if joint function is to be restored.

Open reduction and the use of a transcondylar lag screw is the main method of repair. In addition antirotational devices (K-wire or screw) should be placed in the epicondylar region. Some 77% of dogs treated for lateral or medial condylar fractures go on to regain normal limb function with an average recovery time of 4 weeks, (Denny, 1983).

Intercondylar (Y or T) fractures require good exposure to achieve accurate anatomical reconstruction of the articular surfaces. Although a caudal transolecranon approach has been popular (Bardet et al 1983, Anderson et al 1990) a combined medial and lateral approach (McKee et al 2001) is now routinely used. The medial condyle is reduced first and attached to the humeral diaphysis using a plate or occasionally K-wires in immature dogs, the dog is then turned over and a lateral approach is used to reduce the lateral condyle which is fixed with a transcondylar lag screw + antirotational K-wire.

Prognosis is favourable for return to reasonable function in the majority of animals (64-70%) provided accurate anatomical reduction and good stability is ensured allowing early pain--free elbow mobility (Denny, 1983; Anderson et al 1990., 1990 McKee et al 2001).

Medial epicondylar fractures

This uncommon injury is seen predominantly in immature dogs and results from falls or road traffic accidents. The fragment is distracted by the pull of the antebrachial muscles. If the fragment is large it is re-attached with a lag screw or tension band wire. Smaller bone fragments can be removed and the muscles re-attached to the adjacent fascia.

Fractures of the proximal ulna and olecranon

Fractures of the proximal ulna can be divided into articular fractures involving the semilunar notch of the ulna, or avulsion fractures involving the olecranon process (Muir & Johnson, 1996). In both fracture types the olecranon process is distracted by the strong pull of the triceps group of muscles. Internal fixation using the tension band principle is essential. Tension band wiring with the wire placed over the caudal aspect (tension side) of the ulna is used in most cases however in the case of comminuted fractures of the olecranon a plate is used for fixation. Ideally it is placed on the caudal aspect of the ulna but if this is not possible the lateral side is used.

Small avulsion fractures of the proximal olecranon are treated by lag screw fixation or wiring techniques.

Exposure of the olecranon and proximal ulna shaft is achieved through a curved caudolateral incision made directly over the olecranon. The extensor carpi ulnaris muscle and the flexor carpi ulnaris muscle are separated and retracted to reveal the shaft of the ulna.

Fracture of the anconeal process

Fracture of the anconeal process, not to be confused with un-united anconeal process, is occasionally encountered (McCartney, 1993). Ideally, these cases are treated by lag screw fixation. Anconeal process fracture can also occur as a complication of comminuted fractures of the olecranon.

Fractures of the radial head

Fractures of the radial head are rare, they are often articular and can be associated with fractures of the ulna and elbow luxation. Management has been described by Neal (1975). Articular fractures require accurate anatomical reconstruction and fixation with lag screws and K-wires. Salter Harris Type 1 fractures require K-wire fixation if displaced.

Luxation of the humeroantebrachial joint

Traumatic luxation (dislocation) of the elbow is uncommon, the injury is usually seen in dogs and cats over 1 year of age. This injury results from involvement in road traffic accidents or when the animal catches its leg in a fence and is suspended by the limb. The exact mechanism by which luxation occurs is still open to question however the end result is lateral displacement of the radial head in relation to the humerus. After luxation of the elbow the leg is held forward in semiflexion, with the lower limb abducted and supinated. The elbow joint will be obviously deformed and painful. Flexion and extension are limited.

In the radiographic diagnosis both mediolateral and craniocaudal views should be taken noting any bone fragments which may be associated with collateral ligament avulsion.

Closed reduction should be carried out as soon as possible after the accident. Reduction is achieved under general anaesthesia. The elbow is fully flexed and then the radius and ulna are rotated medially. The elbow is slowly extended until the anconeal process is re-engaged in its normal position between the humeral epicondyles. If the manipulation is successful the radial head and anconeal process "snap " back into place, a normal range of elbow movement is restored and the joint should feel stable. Following radiography to confirm reduction, a Robert Jones Bandage is applied for 7-10 days and exercise is restricted for 4 weeks. Most cases make a satisfactory recovery following closed reduction but, in the long term secondary osteoarthritic change is common (Billings & others, 1992).

Following reduction the collateral ligaments are checked damage for damage by palpation and /or radiographs. If the collateral ligament is avulsed from the humerus it is re-attached using a bone screw + spiked washer. If the ligament is ruptured primary repair should be attempted. Alternatively stability can be restored by replacing the medial collateral ligament with a figure-of-eight heavy gauge braided polyester suture (7 metric Ethibond, Ethicon), or a monofilament material such as Leader line, anchored by two suture screws, one placed in the medial aspect of the humeral condyle and the other in the ulna.

In longstanding, neglected elbow luxations open reduction is carried out in two stages. First a lateral approach is used to allow release of fibrous adhesions so that the radial head and anconeal process can be levered back into their normal position using an elevator in the joint space. After closure of the lateral wound the medial side of the elbow is exposed and the joint stabilised by replacing the medial collateral ligament with a prosthesis.

Results of treatment. In a study of 31 dogs with elbow luxations by Schaeffer & others (1999) it was concluded that a good outcome is likely following early closed reduction provided joint stability is adequate. More proactive use of surgery to restore collateral ligament stability is likely to increase the chances of a successful outcome when instability is noted following closed reduction.

Cranial luxation of the radial head in cats

Cranial luxation of the radial head, associated with rupture of the annular ligament, is occasionally seen in cats. Open reduction is performed and the radial head fixed to the ulna with a lag screw. Prognosis is good, normal function is usually regained and the screw can be left in situ.

Monteggia fracture /luxation

Fracture of the ulna with cranial luxation of the radial head is known as a 'Monteggia' fracture (Boyd & Boals, 1969; Schwartz & Schrader, 1984). Cranial luxation of the radial head occurs when the annular ligament, which normally binds the radial head to the ulna, ruptures and the ulnar shaft is fractured just distal to the elbow. Provided the injury is recent, the luxation can be reduced by manipulation and, because of the strong interosseous attachments between radius and ulna, reduction can be maintained simply by stabilising the ulnar fracture. This is achieved with an intramedullary pin and tension band wire, or a plate if the fracture is comminuted.

Avulsion and ruptures of the tendon of insertion of the triceps muscles

Avulsion or ruptures of the triceps tendon of insertion are occasionally encountered in dogs and cats. Although trauma is the usual cause, the condition has also been reported as a complication of local steroid injection (Davies & Clayton Jones, 1982). Following avulsion, the leg is carried in a semiflexion, the animal is unable to extend the elbow and there is a painful swelling over the point of the olecranon. Repair of the tendon is achieved with Bunnell or Pennington-type locking loop sutures of monofilament nylon. In avulsions, if bone fragments remain with the tendon, a tension band wiring technique is used for reattachment, alternatively a tunnel is drilled transversely through the olecranon to allow attachment of suture material between tendon and bone. Post operatively the elbow should be kept in extension for 4-6 weeks using either Robert Jones bandage or transarticular fixator.

References

1.  Anderson, T.J., Carmichael, S. & Miller, A. (1990) Intercondylar fractures in the dog : A review of 20 cases. Journal of Small Animal Practice 31, 437-442.

2.  Bardet,J.F., Hohn R.B., Rudy, R.L & Olmstead, M.L. (1983) Fractures of the humerus in dogs and cats: A retrospective study of 130 cases. Veterinary Surgery 12, 73-77.

3.  Billings, L.A., Vasseur, P.B., Todoroff, R.F.& Johnson, W.,(1992) Clinical results after traumatic elbow luxation in nine dogs and one cat. Journal of the American Animal Hospital Association, 28, 137-43.

4.  Boyd, H.B & Boals, J.C. (1969) ; The Monteggia lesion. Clinical Orthopaedics and related Research, 66, 94.

5.  Butterworth, S.J. (1992) The influence of distal humeral conformation on the incidence of condylar fractures in the dog. Dissertation submitted in part fulfillment of requirements for the RCVS Diploma in Small Animal Orthopaedics.

6.  Butterworth, S.J. & Innes, J.F.(2001) Incomplete humeral condylar fractures in the dog. Journal of Small Animal Practice 42, 394-398.

7.  Davies. J.C. & Clayton Jones, D.C.(1982), Triceps rupture in the dog following corticosteroid injection. Journal of Small Animal Practice, 23, 779-87

8.  Denny H.R., (1983) Condylar fractures of the humerus in the dog : a review of 133 cases. Journal of Small Animal Practice, 24, 185-97

9.  Marcellin-Little, D.J., De Young, D.J., Ferris, K.K. & Berry, C.M., (1994) Incomplete ossification of the humeral condyle in spaniels. Veterinary Surgery 23, 475-487.

10. McCartney W.T. (1993) Another manifestation of ununited anconeal process in the German Shepherd Dog, Veterinary and Comparative Orthopaedics and Traumatology, 6, 213-14.

11. McKee, WM., May, C. & Macias, C. (2001) Combined medial and lateral approaches for the management of Y-T fractures of the humeral condyle in 15 dogs and 1 cat. BSAVA Congress abstract

12. Muir, P.& Johnson, K.A, (1996), Fractures of the proximal ulna in dogs. Veterinary and Comparative Orthopaedics and Traumatology, 9, 88-94.

13. Neal T.M, (1975) Fractures of the radius and ulna. In Current techniques in Small Animal Surgery. (ed M.J.Bojrab), pp 530-32, Lea & Febiger, Philadelphia, PA.

14. Schaeffer, I.G.F., Wolvekamp, P., Meij., Theijse, L.F.H. & Hazewinkel, H.A.W. (1999) Traumatic elbow luxation in the elbow in 31 dogs. Veterinary and Comparative Orthopaedics and Traumatology 12, 33-39.

15. Schwartz, P.D. & Schrader, S.C. (1984) Ulnar fracture and dislocation of the proximal radial epiphysis (Monteggia lesion) in the dog and cat: a review of 28 cases. Journal of the American Veterinary Medical Association, 185, 190-97.