Computed Tomography-Guided Lag Screw Placement for Treatment of United Anconeal Process in 5 Dogs

Case Description: United anconeal process (UAP) in juvenile dogs is commonly treated with lag screw fixation with or without proximal ulnar osteotomy or fragment removal. Previous reports of lag screw placement describe an open technique to allow for direct visualization; however, minimally invasive techniques are becoming more widely used in veterinary medicine. The purpose of this study was to describe the technique of lag screw placement using CT guidance for the treatment of UAP in dogs.

This was a single center retrospective study of five dogs diagnosed with UAP and treated with CT guided lag screw placement. Sequential focused CT imaging of the proximal ulna was performed to facilitate guide wire placement from the olecranon into the ununited fragment followed by placement of a cannulated lag screw.

In all cases, a lag screw was successfully placed with a median placement time of 59.8 minutes (range 39–75minutes). Four out of five dogs also had a proximal ulnar osteotomy performed. Intraoperative complications included guide wire breakage (n = 1). Postoperative complications included seroma formation (n = 2), and screw removal secondary to implant infection and/or implant loosening (n = 3).

The median time to follow-up was 23 months postoperatively (range: 11 months–3.5 years). Follow-up radiographs showed minimal healing (n = 2), moderate healing (n = 2) and complete healing (n = 1) of the UAP. Owners of all dogs reported clinical improvement with absent to only occasional lameness. Based on these results, CT guidance can be considered when planning treatment for UAP in dogs.

Acknowledgement: None.

No conflict of interest has been declared by the author(s).