Impact of Femoral Stem Prosthesis Tip On Femoral Cortex After Primary Total Hip Arthroplasty (THA)

Abstract

Background: The mechanisms of pain after total hip arthroplasty (THA) is not clear, which may be related to its impact on the femoral cortex caused by improper prosthesis placement. This study was to explore the the impact of the femoral stem prosthesis on the femoral cortex after implantation, and its relationship with postoperative thigh pain. Methods: Totally 172 patients who underwent primary THA were retrospectively analyzed, who were divided into the impact (n=25) and non-impact (n=147) groups. Contact or penetration of the femoral stem prosthesis tip with the distal femoral cortex was defined as impingement. Patients were followed up and recorded.Results: In the patients undergoing primary THA, 25 patients (14.5%) had impact, including 7 males and 18 females. Most of the patients in the impact group were women of small stature. In the impact group, the postoperative thigh pain was more obvious, and the Harris Hip score (HHS) was lower, compared with the non-impact group (P < 0.05). The regression analysis showed that height (OR=1.196; 95%CI: 1.059-1.351; P=0.004) and prosthesis implant angle (PIA) (OR=0.208; 95%CI: 0.074-0.584; P=0.003) were important risk factors for distal femoral cortical impingement in patients who underwent THA. Conclusions: Patients with short stature should have adequate preoperative planning for primary THA, to prevent increased risk of postoperative thigh pain due to impinging femoral stem implants.