Breakage of cementless press-fit femoral stems following total hip arthroplasty in dogs: 14 cases (2013-2023)

ObjectiveTo report breakage of press-fit cementless femoral stems in dogs after total hip arthroplasty (THA).Study designRetrospective case series.AnimalsThirteen dogs (14 stems).MethodsMedical records were obtained for client-owned dogs that underwent THA between 2013 and 2023. Demographic data, implant type and size, time to stem breakage, and radiographic assessment of implant size were recorded. Implant size was compared with the manufacturers' guidelines based on body weight. Treatment-associated complications and overall outcomes were also recorded.ResultsFourteen broken stems were reported in 13 dogs. Thirteen were size #5, #6, or #7 Biologic Fixation (BFX) lateral bolt stems and one was a size #5 standard BFX stem. A +9 head was used in 5 of 11 cases with 17 mm diameter heads. The median time from THA to stem breakage was 522 days (interquartile range, 330-905 days). Ten of the 14 stems were radiographically undersized. The weights of 10 of 13 dogs were at, or exceeded, weight-limit guidelines. Eleven stems were revised with a new stem, two were explanted, and one was partially explanted. Major complications of revision included stem rebreakage, periprosthetic fracture, and pin and tension band-fixation failure. Full function was achieved in 9 of 10 dogs with revised stems based on owner and surgeon assessment.ConclusionMost of the stems that broke were BFX lateral bolt stems and were undersized both radiographically and in comparison with weight-limit guidelines. Revision can be successful, although the complication rate is high.Clinical significanceThe use of small, undersized BFX lateral bolt stems should be avoided.