Case factors for selection of femoral component type in canine hip arthroplasty using a modular system.

Objective: To describe a femoral stem selection process based on case features in dogs treated with total hip replacement (THR) by an expert surgeon, compare complications between implant types, and develop an algorithm for stem type selection.

Study Design: Retrospective study.

Animals: 128 dogs, 135 THR.

Methods: Data collected included breed, age, weight, canal flare index (CFI), and implant type: cementless (BFX), cementless with a collared stem (BFX-C), hybrid (cementless acetabular component with cemented stem), and cemented (CFX).

Results: Of the 135 THRs, 69 BFX, 47 hybrid, and 18 BFX-C were performed. Dogs receiving hybrid (mean 5.5 years) were older than those receiving BFX (2.5 years, p < .0001) and BFX-C implants (2.5 years, p = .0014). The mean weights of dogs with hybrid, BFX, and BFX-C implants were 40.0, 31.0, and 35.3 kg, respectively, with dogs receiving hybrid heavier than those receiving BFX (p < .0001). Mean CFI for hybrid (1.52) was lower than for BFX (1.79, p < .0001) and BFX-C (1.76, p = .0021). Total complication rate was 14.0% with catastrophic complications in 1.5% and no association between implant type and risk of complications (p = .36). Femur fractures occurred in 2.9% of all cases and 1.1% of cementless THR cases.

Conclusions: Dogs receiving hybrid THR were older with lower CFI than dogs receiving BFX and BFX-C and heavier than dogs receiving BFX. There was no difference in complications between groups. Catastrophic complications and femur fractures occurred less frequently compared to recent studies of BFX THR.

Clinical Significance: Careful preoperative assessment and implant selection can reduce complications of canine THR.