Femoral antetorsion after calcar‐guided short‐stem total hip arthroplasty: A cadaver study

Abstract

Calcar-guided short stems in total hip arthroplasty (THA) permit surgeons to successfully reconstruct postoperative femoroacetabular offset, accurately restore leg length, and adequately re-establish a wide range of caput-collum-diaphyseal angles.However, their effect on femoral antetorsion is less known. Indeed, controlling antetorsion of the femoral stem can be challenging because of the differences in individual femoral geometry and curvature. Therefore, we investigated if calcarguided short-stem THA alters femoral antetorsion and compared it with conventional-stem THA. Using 12 Thiel-fixed, full-body cadaver specimens from donors without known hip disorders, we compared an uncemented calcar-guided femoral short-stem prosthesis with an uncemented conventional straight-stem prosthesis. In a paired study setup, each specimen received a calcar-guided short stem on one side and a conventional stem on the other. On the acetabular side, all specimens received a press-fit, monobloc acetabular cup. Femoral antetorsion angles were measured using the Waidelich method, and pre-and post-operative angles of both sides were recorded. The mean preoperative femoral antetorsion angles were similar in both groups (24.8°± 7.5°vs. 23.8°± 6.1°, p = 0.313). Mean postoperative femoral antetorsion angles were 23.0°± 5.5°in short-stem and 13.5°± 7.1°in conventional-stem hips. Short-stem hips had a small but nonsignificant difference in femoral antetorsion angles pre-and post-operatively (1.8°± 3.2°, p = 0.109), while the difference for conventional-stem hips was much larger and highly significant (10.3°± 5.8°, p < 0.001). Calcar-guided short-stem THA effectively restores femoral antetorsion. However, how this affects long-term clinical outcomes and complications warrants further exploration.

A statistical shape analysis for the assessment of the main geometrical features of the distal femoral medullary canal

“…Besides that, no study in the literature has ever investigated how and whether the various anatomical variations depend on the residual length. Furthermore, a SSM of the medullary canal alone would also prevent the outcomes from being affected by confounding factors related to the whole femoral shape (e.g., neck shafts) and allow to investigate the only parameters that are relevant for such district, such as the diameter and the radius of curvature, according to studies on similar anatomical district in terms of shape ( Chantarapanich, et al, 2008 ; Jauch et al, 2014 ; Hochreiter, et al, 2022 ).…”

Femoral Anteversion in Total Hip Arthroplasty: Retrospective Comparison of Short- and Straight-Stem Models Using CT Scans

“…However, due to the continuous development of new implant designs for cementless short-stem THA as well as its increased use and related research, this method is more prominent [ 29 , 30 , 31 ]. Although short-stem designs gained popularity due to their ability to preserve proximal femoral bone stock and provide more natural loading in the proximal femur than straight-stems [ 32 , 33 , 34 , 35 , 36 ], only a limited number of studies have directly compared the two designs in terms of FA reconstruction [ 27 , 37 , 38 ], with short-stems showing higher FA restoration accuracy than straight-stems [ 38 ]. However, more data is needed to verify the superiority of short-stem designs in FA reconstruction and their clinical relevance, considering that various stem designs may affect the parameters of hip geometry reconstruction differently.…”

Stem Design in Total Hip Arthroplasty Influences Ipsilateral Knee Valgus: A Retrospective Comparative Analysis of 2953 Cases

“…Short-stem surgery is more soft-tissue sparing and bone saving [19]. Moreover, the restoration of native femoral offset (FO) and femoral antetorsion has been shown to be more accurate in short-stem THA [19,20].…”