Optimizing the Femoral Offset for Restoring Physiological Hip Muscle Function in Patients With Total Hip Arthroplasty

Abstract

ObjectiveFemoral offset (FO) restoration is significantly correlated with functional recovery following total hip arthroplasty (THA). Accurately assessing the effects of FO changes on hip muscles following THA would help improve function and optimize functional outcomes. The present study aimed to (1) identify the impact of FO side difference on the hip muscle moment arms following unilateral THA during gait and (2) propose the optimal FO for a physiological hip muscle function.MethodsIn vivo hip kinematics from eighteen unilateral THA patients during gait were measured with a dual-fluoroscopic imaging system. The moment arms of thirteen hip muscles were calculated using CT-based 3D musculoskeletal models with the hip muscles’ lines of actions. The correlation coefficient (R) between FO and hip muscle moment arm changes compared with the non-implanted hip was calculated. We considered that the FO reconstruction was satisfactory when the abductor moment arms increased, while the extensor, adductor, and flexor moment arms decreased less than 5%.ResultsA decreased FO following THA was significantly correlated with a decrease of the abductor and external rotator moment arms during the whole gait (R > 0.5) and a decrease of extensor moment arms during the stance phase (R > 0.4). An increased FO following THA was significantly associated with shorter flexor moment arms throughout the gait (R < −0.5) and shorter adductor moment arms in the stance phase (R < −0.4). An increase in FO of 2.3–2.9 mm resulted in increased abductor moment arms while maintaining the maximum decrease of the hip muscles at less than 5.0%.ConclusionAn increase of 2–3 mm in FO could improve the abductor and external rotator function following a THA. Accurate surgical planning with optimal FO reconstruction is essential to restoring normal hip muscle function in THA patients.

Development and Validation of an Artificial Intelligence Preoperative Planning System for Total Hip Arthroplasty

“…It has been reported that reduced femoral offset negatively affected range of motion due to impingement and reduced abductor lever ( 32 ). Gait analysis has shown that changes in femoral offset also influence the function of external rotator, extensor and short flexor muscle during different phase of gait ( 33 ). On the other hand, one study found that significantly increased femoral offset was an important source of elevated ions in metal on polyethylene THA, suggesting possible increased contact force and accelerated wear ( 34 ).…”

Pre-Operative Digital Templating Aids Restoration of Leg-Length Discrepancy and Femoral Offset in Patients Undergoing Total Hip Arthroplasty for Primary Osteoarthritis

“…Most recently, Hu et al quantified the effect of femoral offset difference post-THA [26]. They reported that an appropriate increase of 2-3mm in femoral offset could improve the recovery of hip abduction and external rotation function [26].…”

“…Most recently, Hu et al quantified the effect of femoral offset difference post-THA [26]. They reported that an appropriate increase of 2-3mm in femoral offset could improve the recovery of hip abduction and external rotation function [26]. Consequently, an optimal femoral offset calculated pre-operatively via digital templating, rather than blindly increasing this distance, could reduce muscle imbalance, gait instability, and THA dislocations [26].…”

Acetabular Revision Arthroplasty Based on 3-Dimensional Reconstruction Technology Using Jumbo Cups

“…Based on a 3D computer model, Delp et al (1996) found that superolateral placement of the HCOR resulted in an average reduction 28% in the abductor muscle moment arm. This could lead to muscle imbalance and prosthetic joint dislocations ( Renkawitz et al, 2016 ; Hu et al, 2021 ). Further, Bicanic et al (2009) quantified the relationship between the displacement of HCOR and the joint response force in the experiment and found that upshifting the HCOR by 1 mm will increase the joint response force by 0.1%.…”