Is the contralateral lesser trochanter a reliable reference for planning of total hip arthroplasty \u2013 a 3-dimensional analysis

Julian Hasler,Lazaros Vlachopoulos,Philipp Fürnstahl,Jakob Ackermann,Armando Hoch,Patrick O Zingg

doi:10.1186/s12891-021-04131-w

Julian Hasler, Lazaros Vlachopoulos + Show 4 more

Open Access

https://doi.org/10.1186/s12891-021-04131-w

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Abstract

BackgroundPreoperative templating in total hip arthroplasty (THA) is mandatory to achieve appropriate offset and leg length equality. However, templating methods using the contralateral hip might be susceptible to errors resulting from side-differences in the femoral morphology. The distance of the lesser trochanter to the femoral head center (LTFHD) is a frequently used reference parameter for preoperative planning and intraoperative validation during THA. However, currently no three-dimensional (3D) analysis of side differences of the LTFHD exists.MethodsUsing Computer tomography (CT)-based surface models from 100 paired femora (50 cadavers), side-to-side asymmetry of the LTFHD, femoral length, femoral head diameter (FHD) and femoral antetorsion were analyzed. Univariate linear regression models were established to evaluate potential associations between sides regarding LTFHD and FHD as well as a correlation of these parameters with each other.ResultsStatistically significant side-differences were found for the LTFHD (p = 0.02) and FHD (p = 0.03) with a mean absolute side-difference of 1.6 ± 1.4mm (range 0.1–5.5mm) and 0.4mm ± 0.6mm (range 0–3mm), respectively. The ratio between the LTFHD and FHD was consistent with an average value of 1.16 ± 0.08 and reliable between sides with a correlation coefficient (r) of 0.72 (p < 0.01).ConclusionsThe LTFHD is a reliable reference parameter for preoperative templating and intraoperative validation during THA with a high correlation between sides (r = 0.93, p < 0.01). However, 8 % of the investigated specimens revealed a LTFHD of more than 4mm, which should be anticipated during THA to avoid unsatisfiable results.

Highlights

Restoration of the native biomechanical setting in total hip replacements is crucial for achieving complete functional recovery, stability and good clinical outcomes [1, 2]
Due to altered anatomy and distorted radiological representation of the proximal femur in severely arthritic hips, femoral neck fractures or collapse of the femoral head arising from osteonecrosis of the hip, the preoperative radiographic assessment of limp length and offset of the Hasler et al BMC Musculoskeletal Disorders (2021) 22:268 affected side might be of limited value [11].the unaffected hip is often used to plan and evaluate accuracy of hip reconstruction [4, 12, 13]
Some authors propose the femoral head diameter as a valuable tool to predict the lesser trochanter to the femoral head center (LTFHD) [14,15,16], which might be helpful if pathological conditions exist on both hips

Summary

Introduction

Restoration of the native biomechanical setting in total hip replacements is crucial for achieving complete functional recovery, stability and good clinical outcomes [1, 2]. Some authors propose the femoral head diameter as a valuable tool to predict the LTFHD [14,15,16], which might be helpful if pathological conditions exist on both hips. These templating methods based on plane radiographs may be susceptible to errors resulting from projection errors [17, 18] and side-to-side differences of the 3-dimensional geometry of the proximal femur [19,20,21]. Currently no three-dimensional (3D) analysis of side differences of the LTFHD exists

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