Association of preoperative variables of ipsilateral hip abductor muscles with gait function after total hip arthroplasty: a retrospective study

Editorial: factors influencing the outcome of total hip and knee arthroplasty

BACKGROUND

Total hip and knee arthroplasty for end stage arthritis are among the most cost-effective interventions available in all of medicine. Success of hip and knee arthroplasties is not universal and approximately one in ten patients are not satisfied with their arthroplasty and 10 to 34% of patients have an unfavourable long term pain outcome. The aim of this edition of Arthroplasty was to identify factors associated with: (1) poor joint specific outcome, (2) poor health related quality of life outcome and (3) dissatisfaction following total hip and knee arthroplasty.

METHODS

The scope was deliberately broad to identify factors (known and unknown) that influence outcome of total hip and knee arthroplasty, and of 40 submissions, eight were selected for this special edition after peer review.

RESULTS

Many of the included studies reported subjective patient reported outcome measures as their key outcomes but other objective measures such as muscle mass, timed Up-and-Go test, kneeling ability and postoperative pain are also featured. Some studies involved a focus on early rehabilitation after surgery (ERAS) principles and how to optimise pre-rehabilitation and reduce length of hospital stay readmission and reoperation. The effect of metal allergy and drain usage on outcomes is also explored. A variety of methodologies have been used including one randomised control trial, some machine learning and three systematic reviews investigating the effect of metal allergy on outcomes, associations with postoperative pain and the effect of patella resurfacing.

CONCLUSION

This special edition has advanced our knowledge of factors influencing to the outcome of hip and knee arthroplasty but has also identified several areas of research that need to be addressed to improve the outcomes of our patients.

Preoperative Lower-Limb Muscle Predictors for Gait Speed Improvement after Total Hip Arthroplasty for Patients with Osteoarthritis

This study aimed to identify preoperative lower-limb muscle predictors for gait speed improvement after total hip arthroplasty (THA) with hip osteoarthritis. Gait speed improvement was evaluated as the subtraction of preoperative speed from postoperative speed. The preoperative muscle composition of ipsilateral hip abductors was evaluated using computed tomography. The females (n = 45) showed smaller total cross-sectional areas of the gluteal muscles than the males (n = 13). The gluteus maximus in the females showed lower lean muscle mass area (LMM) and higher ratios of the intramuscular fat area and the intramuscular adipose tissue area to the total muscle area (TM) than the males. Regression analysis revealed that LMM/TM of the glutei medius and minimus may correlate negatively with postoperative improvement in gait speed. Receiver operating characteristic curve analysis for prediction of minimum clinically important improvement in gait speed at ≥0.32 m/s resulted in the highest area under the curve for TM in the upper portion of the gluteus maximus with negative correlation. The explanatory variables of hip abductor muscle composition predicted gait speed improvement after THA more precisely in the females compared with the total group of both sexes. Preoperative muscle composition should be evaluated separately based on sex for the achievement of clinically important improvement in gait speed after THA.

Walking Stability and Risk of Falls

Walking stability is considered a necessary physical performance for preserving independence and preventing falls. The current study investigated the correlation between walking stability and two clinical markers for falling risk. Principal component analysis (PCA) was applied to extract the three-dimensional (3D) lower-limb kinematic data of 43 healthy older adults (69.8 ± 8.5 years, 36 females) into a set of principal movements (PMs), showing different movement components/synergies working together to accomplish the walking task goal. Then, the largest Lyapunov exponent (LyE) was applied to the first five PMs as a measure of stability, with the interpretation that the higher the LyE, the lower the stability of individual movement components. Next, the fall risk was determined using two functional motor tests-a Short Physical Performance Battery (SPPB) and a Gait Subscale of Performance-Oriented Mobility Assessment (POMA-G)-of which the higher the test score, the better the performance. The main results show that SPPB and POMA-G scores negatively correlate with the LyE seen in specific PMs (p ≤ 0.009), indicating that increasing walking instability increases the fall risk. The current findings suggest that inherent walking instability should be considered when assessing and training the lower limbs to reduce the risk of falling.