Post-hip-fracture knee pain in older adults prolongs their hospital stays: A retrospective analysis using propensity score matching.

BACKGROUND AND PURPOSE: Post-hip-fracture knee pain (PHFKP) occurs in ∼28%-37% of patients and contributes to a prolonged length of hospital stay (LOS). Analyses of LOS prolongation due to PHFKP have been limited to univariate analyses that do not consider important confounding factors. After adjusting for important confounding factors, we investigated whether the presence or absence of PHFKP makes a difference in LOS in patients with hip fractures. METHODS: We conducted a retrospective review of the medical records of patients who had undergone postoperative rehabilitation after surgery for a hip fracture. Demographic and clinical information, discharge parameters, and PHFKP development information were collected from the medical records. Using propensity score matching, we performed a two-group comparison of LOS, the functional independence measure (FIM) motor score (FIMm), FIMm gain, and FIMm effectiveness in patients with and without PHFKP. Six variables were included in the calculation of propensity scores: age, sex, body mass index, fracture type, American Society of Anesthesiologists physical status, and independence in activities of daily living at discharge. One-way analysis of variance was used to examine the details of the relationships between LOS and (i) the time of PHFKP development and (ii) pain intensity. RESULTS: We analyzed the cases of 261 patients, of whom 87 (33.3%) developed PHFKP. In propensity score matching, 80 patients were each matched to a patient in the PHFKP or non-PHFKP group. After propensity score matching, a between-group comparison revealed that the PHFKP group had a longer LOS (+11 days) than the non-PHFKP group, and there were no differences in FIMm gain or FIMm effectiveness. The timing of PHFKP development and pain intensity were not related to the LOS. DISCUSSION: Even after adjusting for confounders, the development of PHFKP was found to prolong LOS. Clinicians should be aware of possible LOS prolongation in hip fracture patients with PHFKP.

Predictors of post-hip fracture knee pain in hospitalized older adults with intertrochanteric femoral fracture.

BACKGROUND: Post-hip fracture knee pain (PHFKP) is an important issue that contributes to reduced gait speed and prolonged hospitalization. Femoral morphology has been reported to contribute to the development of PHFKP, but an independent association has not been confirmed and clinically applicable cutoffs for predicting the development of PHFKP remain unclear. OBJECTIVE: To determine whether femoral morphology and knee extension range of motion limitation are independent factors in PHFKP and to determine cutoffs for predicting the development of PHFKP. DESIGN: Retrospective chart review study. SETTING: Convalescent inpatient rehabilitation hospital. PARTICIPANTS: Patients in a convalescent ward after intertrochanteric femoral fracture surgery. MAIN OUTCOME MEASURES: PHFKP development, radiographic femoral morphology (leg length discrepancy and neck-shaft angle), and knee extension range of motion limitation. RESULTS: PHFKP developed in 36 (35%) of the 103 patients enrolled. The PHFKP group had a longer hospital stay (p = .029), greater weight (p = .031), greater knee extension range of motion limitation (p = .001), and more varus neck-shaft angle (p < .001) compared to the non-PHFKP group. Varus neck-shaft angle (odds ratio, 0.85; 95% confidence interval [CI], 0.78-0.92; p < .001) and knee extension range of motion limitation (odds ratio, 1.18; 95% CI, 1.07-1.30; p = .001) were significant factors for PHFKP development. Neck-shaft angle discrepancy and knee extension range of motion limitation demonstrated moderate accuracy in discriminating development of PHFKP according to receiver operating characteristic analysis, with cutoffs of 9.6° and 7.5°, respectively. Areas under the receiver operating characteristic curve were 0.77 (95% CI, 0.66-0.88; p < .001) for neck-shaft angle discrepancy and 0.67 (95% CI, 0.56-0.79; p = .004) for knee extension range of motion limitation. CONCLUSIONS: Varus neck-shaft angle and knee extension range of motion limitation were identified as independent predictors of PHFKP. The cutoff for neck-shaft angle may be useful for predicting PHFKP development and to define an acceptable angle of fracture reduction to prevent PHFKP.

Inpatient knee pain after hip fracture surgery affects gait speed in older adults: A retrospective chart-referenced study.

AIM: Post-hip fracture knee pain (PHFKP) develops in 28-37.4% of patients with hip fracture and contributes to prolonged hospitalization. Although reduced balance and gait speed contribute to falls, the effects of PHFKP remain unclear. This study aimed to clarify whether PHFKP is a factor in balance and gait speed. METHODS: We retrospectively reviewed the medical records of patients after hip fracture. Development of PHFKP, basic information, and physical function were examined. Berg balance scale (BBS) and maximum walking speed (MWS) were collected at discharge. These parameters were compared with the presence or absence of PHFKP. In addition, multiple analyses were conducted with BBS and MWS as dependent variables and PHFKP as one of the independent variables. RESULTS: Of the 146 patients enrolled, 43 (29.5%) developed PHFKP, and 37.2% of patients with PHFKP showed residual symptoms at discharge. Intensity of PHFKP was mostly mild to moderate. The PHFKP group showed an extended length of stay (+13.3 days) and a tendency toward more discharges to facilities compared with the control group. Knee extension range of motion limitation, knee extensor strength, and BBS did not differ between groups, while MWS was significantly lower in the PHFKP group (0.85 ± 0.32 m/s vs. 1.07 ± 0.39 m/s). Multiple analyses showed that development of PHFKP was not associated with BBS, but was associated with decreased MWS (standardized beta = -0.202, P = 0.005). CONCLUSIONS: PHFKP was identified as an independent factor in gait speed decline. PHFKP patients should be monitored for reduced gait speed during rehabilitation. Geriatr Gerontol Int 2021; 21: 830-835.