2021 COA/CORS/CORA Annual Meeting: Impact of Implant Design on Femoral Stem Migration Following Direct Anterior and Direct Lateral Primary Total Hip Arthroplasty

Seventy-nine patients with unilateral hip osteoarthritis scheduled to undergo a primary total hip arthroplasty (THA) via a direct anterior approach (DAA) or direct lateral approach (DLA) were randomized to receive a collard (n=36) or collarless femoral stem (n=33). Specifically, patients undergoing DAA (n=49) were divided into receiving a collard (n=23) and collarless femoral stem (n=26) implants. Similarily, patients undergoing a DLA were divided into receiving collard (n=13) and collarless femoral stem (n=17) implants. Outcomes of interest included implant migration via supine radiostereometric analysis imaging, as well as patient reported outcomes (PROMS). All outcomes were measured up to 1 year post-THA. Results revealed no significant difference for PROMS between the DLA and DAA groups (p>0.05). Implant subsidence at 2 weeks post-THA compared to day of surgery was significantly higher in the DAA group compared to the DLA group in both collared stems (p=0.02) and collarless stems (p=0.001);yet, this difference was not observed after 2 weeks post-operation (p>0.05). Patients in the DAA group had significantly lower implant subsidence when receiving collared stems compared to collarless stems (p=0.01); this was not observed in the DLA group (p=0.894).