A high offset stem design does not increase stem migration under full weight bearing in cementless total hip arthroplasty: a model-based RSA study

Abstract Background High-offset stems in cementless primary total hip arthroplasty (THA) have been potentially associated with early aseptic femoral loosening. This study aimed to evaluate the primary and secondary stability of a cementless high-offset femoral component under full weight-bearing con...

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Main Authors: Tobias Reiner, Robert Sonntag, Jan Philippe Kretzer, Michael Clarius, Eike Jakubowitz, Stefan Weiss, Stefan Kinkel, Tilman Walker, Tobias Gotterbarm, Timo Albert Nees
Format: Article
Language:English
Published: BMC 2025-02-01
Series:Arthroplasty
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Online Access:https://doi.org/10.1186/s42836-024-00290-y
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Summary:Abstract Background High-offset stems in cementless primary total hip arthroplasty (THA) have been potentially associated with early aseptic femoral loosening. This study aimed to evaluate the primary and secondary stability of a cementless high-offset femoral component under full weight-bearing conditions using model-based RSA, comparing it with a standard offset stem in patients undergoing THA. Methods In this prospective, observational, single-center study, 42 patients with end-stage hip osteoarthritis underwent cementless primary THA using either a standard (SL-PLUS Standard) or a high-offset (SL-PLUS Lateral) cementless stem. Radiostereometric analysis (RSA) was employed to monitor stem migration at six weeks and three, six, twelve, and twenty-four months. Clinical outcomes were assessed using the modified Harris Hip Score (HHS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Results There were no significant differences in mean stem subsidence between the groups at any follow-up interval, indicating comparable primary and secondary stability. After minimal initial subsidence (SL-PLUS Standard: up to −0.54 mm; SL-PLUS Lateral: up to −0.73 mm), no further progressive migration was observed. A significant difference in stem anteversion was noted between the groups at six months (P = 0.021) and two years (P = 0.001). The SL-PLUS Lateral group had significantly better WOMAC scores at the two-year follow-up (P = 0.027). Conclusions This RSA study demonstrated similar migration patterns for the high-offset and standard-offset cementless stems within the first two years after operation. Both groups exhibited initial subsidence followed by high secondary stability. Based on the results of this study, the SL-PLUS Lateral is a safe alternative for patients with high femoral offset undergoing cementless THA.
ISSN:2524-7948