Background: Muscle weakness is a key factor in the increase risk of falls and might also play a significant role in the increase of risk of hip fracture. Computed tomography‐measured muscle size and muscle density are well‐established imaging biomarkers used in studies of physical function, frailty or cancer, but limited to hip fracture. In particular, it is warranted to have a better understanding of the performance of muscle size and density in the discrimination of acute hip fractures. We also aim to determine age‐related differences of muscle size and density in healthy controls and hip fracture patients.Methods: Four hundred thirty‐eight low‐energy acute hip fracture cases and 316 healthy controls from the China Action on Spine and Hip Status study were included in the study. Muscle cross‐sectional area and density were measured for the gluteus maximus and gluteus medius and minimus. Areal bone mineral density (aBMD) of the femoral neck and total hip was measured. Using propensity score matching, we generated three samples with cases and controls matched for age, body mass index, and gender: femoral neck fracture (FNF), intertrochanteric fracture (ITF), and any hip fracture vs. controls, respectively.Results: Handgrip strength, gluteus muscle area and density, and bone parameters of the matched hip fracture groups were lower than those of the correspondence control groups, respectively (P < 0.05). The univariate analysis showed that associations of aBMD with FNF and with ITF were significantly weaker than associations between fracture and muscle parameters. Gluteus medius and minimus muscle density showed the highest areas under the curve (AUC) with FNF (0.88, 95% confidence interval, 0.85–0.92) and trochanteric fracture (0.95, 95% confidence interval, 0.92–0.97). The model including all muscle and bone parameters provided the highest AUC (FNF: AUC 0.912; ITF: AUC 0.958), and AUC results of another selected model without muscle density showed that association with fracture significantly dropped (FNF: AUC 0.755; ITF: AUC 0.858). Separate results for the two age groups younger and older than 70 years showed no age‐related significant differences in discriminate models.Conclusions: Muscle density performs better than aBMD from hip computed tomography X‐ray absorptiometry and muscle size in discrimination of hip fracture. Combination of aBMD and muscle density provided the best discrimination. The integration of muscle assessments may trigger a paradigm shift in hip fracture prediction. Gluteus muscle density should also be evaluated as treatment outcome.

Background: Patients with a first hip fracture are at high risk of fracturing their other hip. Despite this, preventive therapy is often not given. Because little is known about specific risk factors of a second hip fracture, we investigated the association with areal bone mineral density (aBMD), muscle size, and density. We also investigated whether muscle parameters predict the risk of a contralateral fracture independently of aBMD.Methods: Three groups were included, one without hip fracture (a subcohort of the China Action on Spine and Hip Status study), one with a first, and one with a second hip fracture. Subjects with fractures were recruited from the longitudinal Chinese Second Hip Fracture Evaluation (CSHFE). Computed tomography scans of CSHFE patients, which were obtained immediately following their first fracture, were used to measure cross‐sectional area and density of the gluteus maximus (G.MaxM) and gluteus medius and minimus (G.Med/MinM) muscles. Computed tomography X‐ray absorptiometry was used to measure aBMD of the contralateral femur. Median follow‐up time to second fracture was 4.5 years. Cox proportional hazards models were used to compute hazard ratios (HR) of second hip fracture risk in subjects with a first hip fracture. Multivariate logistic regressions were used to compare odds ratios (OR) for the risk of a first and second hip fracture.Results: Three hundred and one participants (68.4 ± 6.1 years, 64% female) without and 302 participants (74.6 ± 9.9 years, 71% female) with a first hip fracture were included in the analysis. Among the latter, 45 (79.2 ± 7.1 years) sustained a second hip fracture. ORs for first hip fracture were significant for aBMD and muscle size and density. ORs for a second fracture were smaller by a factor of 3 to 4 and no longer significant for femoral neck (FN) aBMD. HRs for predicting second hip fracture confirmed the results. G.Med/MinM density (HR, 1.68; CI, 1.20–2.35) and intertrochanter aBMD (HR, 1.62; CI, 1.13–2.31) were the most significant. FN aBMD was not significant. G.Med/MinM density remained significant for predicting second hip fracture after adjustment for FN (HR, 1.66; Cl, 1.18–2.30) or total hip aBMD (HR, 1.50; 95% Cl, 1.04–2.15).Conclusions: Density of the G.Med/MinM muscle is an aBMD independent predictor of the risk of second hip fracture. Intertrochanteric aBMD is a better predictor of second hip fracture than FN and total hip aBMD. These results may trigger a paradigm shift in the assessment of second hip fracture risk and prevention strategies.

Displaced pelvic fracture is among the most complicated fractures in traumatic orthopedics, with high mortality and morbidity. Reduction is considered a complex procedure as well as a key part in surgical treatment. However, few robotic techniques have been employed in the reduction of pelvic fracture, despite the rapid advancement of technologies. Recently, we designed a robot surgery system specialized in the autonomous reduction of displaced pelvic fracture and applied it in the true patient for the first time. In this paper, we report its successful clinical debut in the surgery of a displaced pelvic fracture. Total surgery time was 110 min and an anatomic reduction was achieved. We then present a brief overview of the literature about reduction techniques in pelvic fracture and introduce related principles involved in our robot-assisted reduction system.

Summary: The prognostic nutritional index (PNI) is a useful tool for assessing nutritional status using serum albumin and lymphocyte count. This study indicates that a higher preoperative PNI correlates with improved mobility and health-related quality of life during the initial postoperative period in elderly patients with hip fractures. Purpose: To investigate the prognostic value of the prognostic nutritional index (PNI) in predicting mobility and health-related quality of life (HRQoL) in elderly hip fracture patients after surgery. Methods: We prospectively involved patients aged 65 and above, who could walk freely before injury and underwent surgery between 2018 and 2019. Admission PNI was calculated as serum albumin (g/L) + 5 × total lymphocyte count (× 10⁹/L). Patients were classified into two groups based on PNI median value. All patients were followed up by telephone for four times (30-day, 120-day, 1-year, and 3-year after surgery). The Fracture Mobility Score (FMS) and EuroQol 5-Dimension 5-Level (EQ-5D 5L) were used to evaluate mobility and HRQoL, respectively. Results: Of 705 eligible patients, 487 completed all assessments. Patients in the higher PNI group had a significantly increased possibility of achieving unrestricted mobility at the 120-day follow-up (OR 1.69, 95% CI 1.10–2.61, P.adj = 0.017), while no significant differences were observed at other follow-ups. Additionally, patients in the higher PNI group had a significantly higher EQ-5D utility value at the 30-day follow-up (P.adj = 0.015). A linear regression model with adjusting for all confounders showed that admission PNI value was positively associated with EQ-5D utility values at 30-day, 120-day, and 1-year follow-up assessments (P.adj = 0.011, P.adj = 0.001, and P.adj = 0.030, respectively). However, this correlation was not observed at the 3-year time point (P.adj = 0.079). Conclusion: The PNI is a valuable predictor of functional outcomes in elderly patients with hip fractures following surgery.