Background This study aimed to identify the association of preoperative variables of ipsilateral hip abductors with gait function after total hip arthroplasty (THA). Methods This study enrolled 42 patients who underwent unilateral primary THA for osteoarthritis. Gait speed and Timed Up-and-Go test were conducted 6 months postoperatively. Preoperative composition of the glutei medius and minimus and the upper portion of gluteus maximus was evaluated by computed tomography. Cross-sectional area ratio of individual composition to the total muscle was calculated. Preoperative variables associated with gait speed and Timed Up-and-Go test after THA were identified by using stepwise regression analysis. Results Faster gait speed and shorter Timed Up-and-Go test correlated with smaller cross-sectional area of low-density lean tissue or intramuscular adipose tissue (low-density lean tissue plus intramuscular fat) in the glutei medius and minimus and lower cross-sectional area ratio of low-density lean tissue to the total glutei medius and minimus. Faster gait speed and shorter Timed Up-and-Go test also correlated with larger cross-sectional area of lean muscle mass in the gluteus maximus, higher cross-sectional area ratio of lean muscle mass to the total gluteus maximus, and lower cross-sectional area ratio of intramuscular fat or intramuscular adipose tissue to the total gluteus maximus. Faster gait speed additionally correlated with larger total cross-sectional area of the gluteus maximus. Regression analysis showed that the total cross-sectional area of the gluteus maximus and the low-density lean tissue cross-sectional area of the glutei medius and minimus were the explanatory variables of gait speed and Timed Up-and-Go test after THA, respectively. Conclusions There was a potential association between preoperative composition of ipsilateral hip abductors and gait function 6 months after THA. This study indicates a predictive role of preoperative assessment of ipsilateral hip abductor composition in the recovery of gait function after THA.

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Purpose Fragility fractures of the pelvis (FFPs) type IIIa in the Rommens classification include unilateral iliac fractures as well as pubic rami fractures. We devised a new, less-invasive fixation technique to achieve increased stability for FFPs type IIIa. The aim of this study was to describe this procedure and report the preliminary clinical results. Methods A total of 14 geriatric patients (> 60 years old) who sustained FFP type IIIa caused by low-energy trauma were surgically treated with interdigitating screw fixation including a trans-pubic screw in a retrograde manner and two trans-iliac screws from the anterior inferior iliac spine toward the posterior inferior iliac spine. All iliac fractures were displaced with external rotation, and closed reduction was performed. Percutaneous screw fixation, in which fully threaded screws were in contact with each other, provided stable fixation allowing early mobilization. Results A median decrease in pain levels by post-operative day two was 4.5 compared with pre-operatively using a numerical rating scale. While full weight-bearing was allowed from four weeks post-operatively in the initial five patients, immediate full weight-bearing was instructed as tolerated for the subsequent nine patients. No complications were encountered during the perioperative period. At the final follow-up, all fractures were united without fixation loss, screw dislodgment, or hardware failure. Conclusions This procedure of closed reduction and interdigitating screw fixation for FFP type IIIa appears to represent a safe, reliable technique. Our experience suggests that interdigitating fixation for FFP type IIIa is effective for relieving pain and promoting early mobilization in elderly patients.

Aims This study aimed to evaluate sagittal spinopelvic alignment (SSPA) in the early stage of rapidly destructive coxopathy (RDC) compared with hip osteoarthritis (HOA), and to identify risk factors of SSPA for destruction of the femoral head within 12 months after the disease onset. Methods This study enrolled 34 RDC patients with joint space narrowing > 2 mm within 12 months after the onset of hip pain and 25 HOA patients showing femoral head destruction. Sharp angle was measured for acetabular coverage evaluation. Femoral head collapse ratio was calculated for assessment of the extent of femoral head collapse by RDC. The following parameters of SSPA were evaluated using the whole spinopelvic radiograph: pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), sagittal vertical axis (SVA), thoracic kyphosis angle (TK), lumbar lordosis angle (LL), and PI-LL. Results The HOA group showed higher Sharp angles compared with the RDC group. PT and PI-LL were higher in the RDC group than the HOA group. SS and LL were lower in the RDC group than the HOA group. No difference was found in PI, SVA, or TK between the groups. Femoral head collapse ratio was associated with PT, SS, SVA, LL, and PI-LL. A PI-LL > 20° and a PT > 30° correlated with greater extent of femoral head destruction by RDC. From regression analysis, SS and SVA were significantly associated with the femoral head collapse ratio within 12 months after disease onset. Conclusion Compared with HOA, RDC in the early stage correlated with sagittal spinopelvic malalignment. SS and SVA may partially contribute to the extent of femoral head destruction by RDC within 12 months after the onset of hip pain. The present study indicates a potential role of SSPA assessment in identification of RDC patients at risk for subsequent bone destruction. Cite this article: Bone Jt Open 2022;3(1):77–84.

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