The purpose of this study is to determine the relationship between preoperative fatty infiltration of the lower extremity muscles and walking speed two weeks after THA.
This was a single institution retrospective cohort study. Participants in the study underwent primary THA. Exclusion criteria were: (1) non-Japanese nationality, (2) osteonecrosis of the femoral head, (3) post-THA complications. The outcome of this study was walking a normal, comfortable speed two weeks after THA. A decrease in walking speed was defined as less than 0.8 m/s (coded 0, non-decreased group; coded 1, decreased group). Fatty infiltration in each muscle was assessed using non-contrast X-ray computed tomography images obtained during a detailed preoperative examination. The psoas major, gluteus medius and minimus, quadriceps, and triceps surae were assessed bilaterally. The relationship between fatty infiltration of each skeletal muscle and walking speed was analyzed using multivariate logistic regression analysis (covariates: age, sex, BMI, and postoperative pain while walking). Separate analyses were conducted for the operative and nonoperative sides.
A total of 182 participants (26 men and 156 women, mean age: 65.3 years, range: 41-91 years) were included in the analyses. Of the participants, 53 (29.1%) were classified in the decreased walking speed group. On the operative side, the analysis identified fatty infiltration of the gluteus medius (adjusted odds ratio, 0.94; 95% CI, 0.90–0.99) as a significant determinant of decreased walking speed after THA. On the nonoperative side, the analysis identified fatty infiltration of the quadriceps muscle (adjusted odds ratio, 0.92; 95% CI, 0.84–0.99) as a significant determinant of decreased walking speed after THA. There was no problematic multicollinearity among the independent variables or covariates entered into each model.
In patients who had undergone THA, preoperative increased fatty infiltration of the gluteus medius on the operative side and the quadriceps on the nonoperative side was associated with a decrease in walking speed two weeks postoperatively.
Our study findings suggest that evaluation and appropriate intervention of fatty infiltration of the gluteus medius muscle on the operative side and the quadriceps muscles on the nonoperative side might help to prevent a decrease in postoperative walking speed in patients scheduled for THA. On the other hand, because this is a single institution retrospective cohort study, the generalizability of the results and the effect of unmeasured factors on walking speed must be considered.
walking speed
fatty infiltration
