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Equine April 2008 (Vol 3, No 3)

Making the Rounds: Surgical Treatment of an Ulnar Fracture Complicated by Anconeal Process Fragmentation—Case Presentation

by Ronald E. Whitford, DVM

    A case commentary available here.

    Ulnar fractures are relatively common in horses.1,2 Their treatment depends on fracture configuration and patient age, but most are treated by internal fixation using a bone plate applied to the caudal aspect of the bone, and the prognosis for return to full function is favorable in most cases.2,3 Comminuted ulnar fractures, however, carry a less positive prognosis.4,5 Fractures complicated by anconeal process fragmentation are relatively rare in horses and, as such, receive little attention in veterinary textbooks. Different statements on the significance of anconeal process fragmentation have been reported: according to one author, ulnar fractures involving the anconeal process warrant a guarded prognosis,6 whereas the authors of a more recent paper concluded that anconeal process fragmentation per se does not significantly influence the prognosis of comminuted ulnar fractures.5

    This article presents the treatment and long-term follow-up of an equine ulnar fracture involving the anconeal process.

    Clinical Signs and Diagnosis

    A 7-year-old, 1,151-lb (523-kg) Warmblood gelding was referred to Skara Equine Hospital for treatment of an ulnar fracture in the right forelimb. The fracture had occurred 3 days earlier while the horse was on pasture. On admission, the horse refused to bear weight on the affected limb. The elbow appeared slightly dropped with the carpus held in flexion. A moderate soft-tissue swelling in the elbow region was observed, and pain was elicited on deep palpation and manipulation of the olecranon. Radiography showed a comminuted articular fracture of the ulna with a large, displaced anconeal process fragment (Figure 1). Based on these findings, it was decided to treat the fracture surgically.

    Surgery

    In preparation for surgery, penicillin (11 mg/kg IV), gentamicin (6 mg/kg IV), and flunixin meglumine (1 mg/kg IV) were administered. The horse was premedicated with acepromazine (0.05 mg/kg IM), and anesthesia was induced with guaifenesin (50 mg/kg IV) and thiopentone (5 mg/kg IV) and maintained with isoflurane in oxygen using a semiclosed circuit system. The horse was placed in left lateral recumbency. The right elbow region was prepared for aseptic surgery. An approximately 3-inch (8-cm) caudolateral elbow joint arthrotomy was performed, through which an anconeal process fragment roughly an inch (2 x 3 cm) in diameter was retrieved. Careful digital palpation of the caudal aspect of the elbow joint did not reveal further fragmentation. The joint cavity was lavaged with sterile saline, and the arthrotomy was closed routinely.

    An approximately 10-inch (25-cm) curvilinear incision was made that arced over the olecranon and extended distally on the caudolateral aspect of the antebrachium in the depression formed by the ulnaris lateralis muscle and the ulnar head of the deep digital flexor muscle. The incision was continued down through the fascial septum between the two muscles, which were subperiosteally elevated from the ulna, thereby exposing the fracture. A fracture hematoma was evacuated and the fracture line debrided of fibrin. The fracture was reduced and a 10-hole narrow dynamic compression plate contoured to the olecranon and caudal ulna. The proximal part of the plate was contoured so as to extend over the caudal aspect of the olecranon tuber. To enable placement of the plate, a portion of the insertion of the triceps muscle was elevated. The plate was affixed with ten 5.5-mm cortex screws that were all applied in neutral positions (Figure 2). Intraoperative radiography was used to evaluate the length and position of the screws. Finally, the surgical site was lavaged with sterile saline and the incision was closed in three layers, using number 0 polyglactin 910 suture applied in a continuous pattern and stainless steel skin staples. Sterile bandages were placed over the incisions and secured with number 1 nylon suture in a continuous pattern.

    Outcome

    Postoperatively, penicillin (11 mg/kg IV bid), genta­micin (6 mg/kg IV sid), and flunixin meglumine (1 mg/kg IV sid) were administered for 2 weeks, after which only flunixin meglumine was administered. The horse was able to carry full weight on the right forelimb immediately after recovery from anesthesia. The ban­dages were removed 2 days after surgery. Partial dehiscence of the most proximal part of the ulnar incision occurred 1 week postoperatively. This part was treated with daily wound lavage with sterile saline until complete wound contraction had taken place 1 week later. No other postoperative complications were observed.

    The horse was discharged from the hospital 19 days after surgery. Instructions to the owner included continued medication with flunixin meglumine (1 mg/kg PO sid) for 10 days and stall confinement until a follow-up examination at the hospital was performed.

    After discontinuation of the medication, the owner reported that the horse had become increasingly lame in the right forelimb. On examination, the horse was moderately lame at the walk. Radiography was unaltered (i.e., there were no signs of implant failure). It was decided to continue NSAID administration for an additional 10 days (phenylbutazone, 2 mg/kg PO bid).

    At follow-up 7 weeks later, the horse was grade 3 of 5 lame in the right forelimb at the trot. No pain was elicited on palpation of the elbow region. Only slight swelling at the surgical incisions was observed, and radiography showed the position of the implant to be unaltered. However, one of the screws was judged to be too close to the joint surface on the proximal aspect of the radius, a fact that had been overlooked in previous radiographs (Figure 2). The screw was removed, with the patient under general anesthesia, via a 3-inch (8-cm) incision on the caudal aspect of the ulna. Instructions to the owner entailed continued stall confinement.

    At a second follow-up 4 weeks later, the horse was grade 2 of 5 lame and radiography demonstrated ongoing fracture healing. The horse was allowed access to a small paddock. Seven months after the fracture occurred, the lameness was reduced to grade 1 of 5 and radiography revealed further fracture healing. Free pasture exercise was allowed.

    At the final follow-up 16 months after injury, the horse was no longer lame in the right forelimb. Radiography revealed complete fracture healing with no signs of elbow joint disease (Figure 3). The owner reported that the horse had been put back into training 2 months before the examination and that no signs of lameness or discomfort had been observed.

    Discussion

    The literature on ulnar fractures complicated by anconeal fragmentation in horses is scarce, and statements about the clinical significance of this type of injury conflict.5,6 Only two cases of adult horses that were treated by plate fixation of the fracture and extirpation of an anconeal process fragment have been described in the literature.5 One of these horses was sound 2 years after injury; the other was euthanized due to persistent severe lameness in the injured limb. Successful, similar management of bilateral ulnar fractures with anconeal fragmentation in a 7-month-old foal has also been reported.7 The present report lends further credence to the assumption that the prognosis is not adversely affected by anconeal process fragmentation per se and that these fractures carry the same (guarded) prognosis as other comminuted ulnar fractures.5 The present and previously reported successful cases demonstrate that clinical restitution is indeed possible after fracture fixation and fragment removal.

    In the present case, the convalescence period was relatively long. The horse was still lame in the affected limb at follow-up 7 months after surgery. Normally, less than 4 months is required for long-bone fracture healing in adult horses.8 Prolonged lameness after fracture repair indicates fracture instability, infection, or, in the case of articular fracture, persistent synovitis or degenerative joint disease due to incongruent joint surfaces.2 In this case, joint incongruence caused by removal of a significant part of the anconeal process is probably the main reason that the convalescence was prolonged. However, the horse did not develop clinically significant or radiographically detectable degenerative joint disease. Another possible explanation for, or contributing factor to, the prolonged convalescence could be the screw that seemingly was placed too close to the joint surface on the proximal aspect of the radius. However, it was difficult to determine whether part of the screw actually entered the joint cavity, and screw removal did not result in an immediate reduction in the degree of lameness.

    In this case, the implant was left in place with no apparent untoward effects. It still remains to be determined whether implants should be removed after healing of ulnar fractures in adult horses. In two published case series on surgical treatment of ulnar fractures, implant removal was carried out only in cases of draining sinus formation.4,9 Based on these case series and an additional series in which none of the implants were removed,10 it seems that most adult horses function well with their implants left in place. Generally, implants should be removed if one or more of the following conditions exist: infection, broken or loose screws, growth disturbance caused by the implant in foals and young horses, or lysis beneath one or more screw heads with associated lameness.11

    In conclusion, the present case demonstrates that successful surgical management of an ulnar fracture complicated by anconeal process fragmentation is possible.

    Downloadable PDF

    1. Turner AS. Fractures of the olecranon. Vet Clin North Am 1983;5:275-283.

    2. Watkins JP. The radius and ulna. In: Auer JA, Stick JA, eds. Equine Surgery. Philadelphia: WB Saunders; 1999: 831-841.

    3. Nixon AJ. Fractures of the ulna. In: Nixon AJ, ed. Equine Fracture Repair. Philadelphia: WB Saunders; 1996: 231-241.

    4. Denny HR, Barr ARS, Waterman A. Surgical treatment of fractures of the olecranon in the horse: a comparison review of 25 cases. Equine Vet J 1987;19:319-325.

    5. Anderson DE, Allen D, DeBowes RM. Comminuted, articular fractures of the olecranon process in horses: 17 cases (1980 to 1990). Vet Comp Orthop Traum 1995;8:141-145.

    6. Monin T. Repair of physeal fractures of the tuber olecranon in the horse, using a tension band method. JAVMA 1978;172:287-290.

    7. Scott EA, Mattoon JS, Adams JG, et al. Surgical repair of bilateral comminuted articular ulnar fractures in a seven-month-old horse. JAVMA 1998;212:1380-1382.

    8. Ducharme NG, Nixon AJ. Delayed union, nonunion, and malunion. In: Nixon AJ, ed. Equine Fracture Repair. Philadelphia: WB Saunders; 1996:354-358.

    9. Donecker JM, Bramlage LR, Gabel AA. Retrospective analysis of 29 fractures of the olecranon process of the ulna. JAVMA 1984;185:183-189.

    10. McGill CA, Hilbert BJ, Jacobs KV. Internal fixation of fractures of the ulna in the horse. Aust Vet J 1982;58:101-104.

    11. Nixon AJ, Watkins JP, Auer JA. Principles of fracture fixation. In: Nixon AJ, ed. Equine Fracture Repair. Philadelphia: WB Saunders; 1996:63-86.

    References »

    NEXT: Making the Rounds: Surgical Treatment of an Ulnar Fracture—Case Notes and Commentary

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