Olecranon Fracture
The anconeal process of the olecranon of the ulna along with the deep fossa of the condyle of the humerus, form the elbow joint [Figure 1.]. The large olecranon extends high above the elbow joint and projects onto the caudal part of the fifth rib (Dyce et al., 2010).
Fracture of the olecranon occurs fairly commonly in horses with the ulna being one of the most commonly fractured long bones in the horse (Janicek et al., 2006; Metcalf et al., 1990; Stashak, 2002; Swor et al., 2006). The olecranon operates as a lever for the triceps however is not weight bearing. There are different types of fracture: articular or nonarticular, displaced or nondisplaced, comminuted or simple, open or closed (Pasquini et al., 2005; Stashak, 2002; Swor et al., 2006). There are 6 types of fractures [Figure 2.] with types 1 and 2 classed as Salter-Harris fractures which involve the growth plate in immature horses which are generally less than 12 months of age. Type 1 fractures involve the physis with separation and may also have a significant distraction of the bone epiphysis. Foals under 3 months of age are most vulnerable to this type of fracture. Type 2 fractures spread down through the caudal half to two thirds of the physis and enter the humeroradial joint. Weanlings and yearlings are most susceptible to this type of fracture. Closure of the proximal ulnar physis is complete at 27 months of age however growth slows significantly at 15 to 18 months of age, greatly decreasing the incidence of type 1 and 2 fractures and an increase in fractures of the diaphysis. Types 3-6 involve fracture of the diaphysis of the olecranon with most fractures in adults being articular, complete and moderately displaced. The displacement occurs from tension created by the triceps muscle and the level of displacement stems from the level of fracture in the ulna. Type 6 fractures, distal to the radio-humeral articulation are minimally displaced due to the radioulnar interosseous ligament attachments. Fracture separation is more significant on the caudal cortex of the ulnar as it does not have the humeroulnar ligaments and joint capsule for support (Stashak, 2002; Swor et al., 2006). The most common causes of a fracture of the olecranon in adults is trauma (from a kick or impact), misstep, penetrating wounds or falls (Janicek et al., 2006; Pasquini et al., 2005; Stashak, 2002; Swor et al., 2006). In foals, olecranon fractures are mostly attributed to direct-impact trauma or tensile overload from the triceps during sudden falls, galloping or bucking (Stashak, 2002).
Prognosis is good for any sized horse with surgical treatment. There is a poor to good prognosis for horses which are treated in a conservative manner, with a good prognosis for those with nonarticular type 1 and 4 fractures and nondisplaced articular fractures and prognosis is guarded for those with contaminated open fractures (Pasquini et al., 2005). Prognosis for displaced type 1 and 2 physeal fractures depend of the foals age and time elapsed between injury and surgery for repair. Foals less than 3 months are more difficult to repair surgically as their bones are not strong enough to hold the implants however the hook plate is more successful in foals of this age (Pasquini et al., 2005; Stashak, 2002).
Figure 2. The different types of olecranon fractures which can occur in the horse (Stashak, 2002).
References
Annettevet 2010, 'Equine elbow joint', WordPress.com.
Dyce, K. M., Sack, W. O. and Wensing, C. J. G. 2010, Textbook of Veterinary Anatomy, 4th ed., Missouri, Saunders Elsevier .
Janicek, J. C., Rodgerson, D. H., Hunt, R. J., Spirito, M. A., Thorpe, P. E. and Tessman, R. K. 2006, 'Racing prognosis of horses following surgically repaired olecranon fractures', The Canadian Veterinary Journal, vol. 47, no. 3, pp. 241-245.
Pasquini, C., Jann, H., Pasquini, S. & Bahr, R. 2005, Guide to Equine Clinics Lameness, 2nd ed., Texas, Sudz Publishing.
Metcalf, M. R., Tate, L. P., Sellett, L. C. and Henry, M. 1990, 'Radiographic and scintigraphic imaging of a proximal radial physeal injury in a young horse induced by olecranon fracture repair', Equine Veterinary Journal, vol. 22, no. 1, pp. 56-69.
Stashak, T. S. 2002, Adam’s Lameness in Horses, 5th ed., Maryland, Lippincott Williams & Wilkins.
Swor, T. M., Watkins, J.R., Bahr, A., Epstein, K. L. and Honnas, C.M. 2006, 'Results of plate fixation of type 5 olecranon fractures in 20 horses', Equine Veterinary Journal, vol. 38, no. 1, pp. 30-34.
Figure 1. The equine elbow joint showing the olecranon (Annettevet, 2010).
- History of acute non-weight-bearing lameness (Janicek et al., 2006; Pasquini et al., 2005; Stashak, 2002).
- Similar presentation to radial nerve paralysis (Pasquini et al., 2005).
- Dropped elbow, the leg is dragging, swinging from the shoulder with loss of triceps muscle contraction resulting in carpal flexion and an inability to extend the elbow or bear weight (Janicek et al., 2006; Pasquini et al., 2005; Stashak, 2002; Swor et al., 2006).
- In nondisplaced or incomplete fractures, particularly in foals, a subtle lameness appears (Pasquini et al., 2005).
- Heat, pain and swelling are also present (Pasquini et al., 2005; Stashak, 2002).
- The elbow region is visibly swollen on the caudal surface with the level of swelling and lameness is generally indicative of the level of injury (Stashak, 2002).
- In nondisplaced fractures which were caused several weeks ago, swelling of the elbow is the most localised sign with limb manipulation remaining painful (Stashak, 2002).
- To diagnose the condition the horse must first be visually assessed and the medial and lateral sides of the olecranon must be palpated for crepitation and swelling (Pasquini et al., 2005, Stashak, 2002).
- Radiographs should also be taken to determine the extent of the fracture. Radiographing the lateral view is most important and the radiograph should include six inches proximal to the elbow due to the possibility of distraction of the proximal fragment. For a Salter type 1 fracture radiographs should be taken with the limb flexed laterally. The proximal region of the radius should also be radiographed to ensure a comminuted fracture has not occurred (Pasquini et al., 2005). While the lateral view is most important for diagnosis, the both mediolateral and craniocaudal radiographs should be taken to determine the conformation of the fracture. Radiographs of the opposite elbow can also be useful in determining the degree of displacement (Stashak, 2002).
Clinical Signs & Diagnosis
Treatment & Prognosis
- Depends on the type and characteristics of the fracture as well as the age of the horse (Stashak, 2002).
- For a nondistracted, nonarticular fracture (types 1-4& 6) of the radio-ulnar joint, distal semilunar notch or distally, conservative treatment can be undertaken with stall rest for 6-8 weeks. A bandage and splint to the caudal aspect of the limb or a PVC pipe or Thomas pipe splint can be used from the ground up the forearm to prevent carpal flexion and contraction, prevent further displacement and allow for weight bearing. Radiographs should be taken periodically to monitor the separation and to ensure further displacement does not occur (Pasquini et al., 2005; Stashak).
- For an open wound surgery should be delayed and an antibiotic course began (Pasquini et al., 2005).
- Surgical treatment involves the tension band principle. The surgery is approached between ulnaris lateralis and the ulnar head of the deep digital flexor muscle over the olecranon. Articular reconstruction is key. This is done in displaced and nonarticular proximal fractures by cortical screws and figure 8 wire. For a comminuted, articular or distracted fracture, a dynamic compression plate is fitted. It must be contoured to fit the caudal side of the olecranon and a contour plate should be placed over the top of olecranon for proximal fractures. Screws should not be placed through articular surfaces or into the radius of foals less than 6 months of age (Janicek et al., 2006; Pasquini et al., 2005; Metcalf et al., 1990; Stashak, 2002; Swor e al., 2006).
- Horses younger than 6 months may be treated with a combination of screws/pins and wires, tension band wires solely or using an Arbeitsgemeinschaft fur Osteosynthesefragen/Association for the Study or Internal Fixation (AO/ ASIF) hook plate. The dynamic plate however has been found to be superior (Janicek 2006; Stashak, 2002).
- Post operation, an instant improvement should be evident, the distal limb should be bandaged to prevent oedema and perioperative antibiotics should be given. The horse should be kept stabled for 6-8 weeks for foals and 4 months in adults (Pasquini et al., 2005).
- The dynamic compression plate can remain in the horse unless it is affecting its athletic ability or if it is in a foal and has been placed across a radial growth plate (Pasquini et al., 2005).
- If treated conservatorily the following can occur as a result: ankyloses, angular limb deformity of the opposite limb, flexural deformity of the affected limb, arthritis, chronic elbow pain, degenerative joint disease and non-union due to distraction (Pasquini et al., 2005; Metcalf et al., 1990; Stashak, 2002).
