Peri-prosthetic bone remodelling after novel short-stem neck-sparing total hip arthroplasty

• Published in: The Journal of arthroplasty 2016
• Main Authors: Tran, Phong, Mr, Zhang, Benny, Dr, Lade, Justin, Mr, Pianta, Robert, Mr, Unni, Raghavan, Mr, Haw, Chris, Mr
• Format: Article
• Language: English
• Subjects: Orthopedics
• ISSN: 0883-5403
• DOI: 10.1016/j.arth.2016.04.023

Abstract Background Short femoral stems have been designed with the aims of reducing proximal bone loss, improving load transfer, and increasing compressive loads at the medial proximal femoral calcar. This study examines bone mineral density changes associated with a novel neck sparing short femoral stem design. Methods The study was a prospective, single centre, multi-investigator consecutive series which assessed bone-remodelling changes after insertion of the MSA™ Stem (Global Orthopaedic Technology). Dual Energy X-ray Absorptiometry (DEXA) scans were performed preoperatively and postoperatively at 6, 12 and 24 months assessing the BMD at the 7 Gruen zones. The secondary objectives assessed were the Harris Hip Score (HHS), SF-12 preoperatively and perioperative complications. Results Thirty-nine THAs were performed on thirty-seven patients, with twenty seven patients completing the 24 month Dexa Scan. The overall pre-operative baseline BMD was 0.2. At 6 months, the Gruen Zone BMD had increased significantly in all zones in comparison to the preoperative mean BMD. Between 6 months and 24 months, there were only slight changes in the Gruen Zones, with small gains in Zones 1-2 and Zones 4-6, with no Zone showing a significant decrease. The Harris Hip Score improved from a pre-operative mean of 39.7 to 75.3, whilst the SF 12 score also improved from 32.6 to 49 at 24 months. However, five patients had aseptic loosening requiring revision surgery (4 femoral, 1 acetabular component). Conclusions Short stem neck sparing femoral stem prosthesis has the capacity to address the stress-shielding problem identified in femoral stems. However, the high early revision rate is a significant issue.