Weight-bearing asymmetry in individuals post-hip fracture during the sit to stand task

Improving Interpretation of the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Scale for Specific Tasks in Community-Dwelling Older Adults

BACKGROUND AND PURPOSE

New generic patient-reported outcomes like the Patient-Reported Outcomes Measurement Information System (PROMIS) are available to physical therapists to assess physical function. However, the interpretation of the PROMIS Physical Function (PF) T-score is abstract because it references the United States average and not specific tasks. The purposes of this study were to (1) determine convergent validity of the PROMIS PF scale with physical performance tests; (2) compare predicted performance test values to normative data; and (3) identify sets of PROMIS PF items similar to performance tests that also scale in increasing difficulty and align with normative data.

METHODS

Community-dwelling older adults (n = 45; age = 77.1 ± 4.6 years) were recruited for this cross-sectional analysis of PROMIS PF and physical performance tests. The modified Physical Performance Test (mPPT), a multicomponent test of mostly timed items, was completed during the same session as the PROMIS PF scale. Regression analysis examined the relationship of mPPT total and component scores (walking velocity, stair ascent, and 5 times sit to stand) with the PROMIS PF scale T-scores. Normative data were compared with regression-predicted mPPT timed performance across PROMIS PF T-scores. The PROMIS PF items most similar to walking, stair ascent, or sit to stand were identified and then PROMIS PF model parameter-calibrated T-scores for these items were compared alongside normative data.

RESULTS AND DISCUSSION

There were statistically significant correlations (r = 0.32-0.64) between PROMIS PF T-score and mPPT total and component scores. Regression-predicted times for walking, stair ascent, and sit-to-stand tasks (based on T-scores) aligned with published normative values for older adults. Selected PF items for stair ascent and walking scaled well to discriminate increasing difficulty; however, sit-to-stand items discriminated only lower levels of functioning.

CONCLUSIONS

The PROMIS PF T-scores showed convergent validity with physical performance and aligned with published normative data. While the findings are not predictive of individual performance, they improve clinical interpretation by estimating a range of expected performance for walking, stair ascent, and sit to stand. These findings support application of T-scores in physical therapy testing, goal setting, and wellness plans of care for community-dwelling older adults.

A Novel Simplified System to Estimate Lower-Limb Joint Moments during Sit-to-Stand

To provide effective diagnosis and rehabilitation, the evaluation of joint moments during sit-to-stand is essential. The conventional systems for the evaluation, which use motion capture cameras, are quite accurate. However, the systems are not widely used in clinics due to their high cost, inconvenience, and the fact they require lots of space. To solve these problems, some studies have attempted to use inertial sensors only, but they were still inconvenient and inaccurate with asymmetric weight-bearing. We propose a novel joint moment estimation system that can evaluate both symmetric and asymmetric sit-to-stands. To make a simplified system, the proposal is based on a kinematic model that estimates segment angles using a single inertial sensor attached to the shank and a force plate. The system was evaluated with 16 healthy people through symmetric and asymmetric weight-bearing sit-to-stand. The results showed that the proposed system (1) has good accuracy in estimating joint moments (root mean square error < 0.110 Nm/kg) with high correlation (correlation coefficient > 0.99) and (2) is clinically relevant due to its simplicity and applicability of asymmetric sit-to-stand.

Asymmetries Identified in Sit-to-Stand Task Explain Physical Function After Hip Fracture

BACKGROUND

Several known demographic and functional characteristics combine to predict physical function after hip fracture. Long-term weight-bearing asymmetries, evident during functional movements after hip fracture, contribute to limited mobility and large asymmetries in muscle function are linked to a high rate of injurious falls. Although postfracture mobility is commonly measured as whole body movement, a force-plate imbedded chair can identify individual limb contributions to an important task like moving from a sitting to standing position. The modified Physical Performance Test (mPPT) and stair climb test (SCT) are reliable, valid measures of function that predict independence after hip fracture. The purpose of this study was to determine to what extent asymmetry during a sit-to-stand task (STST) predicts function (mPPT, 12-step SCT), above and beyond other known predictors.

METHODS

Thirty-one independent community-dwelling older adults, recently discharged from usual care physical therapy (mean [standard deviation], 77.7 [10.5] years, 10 male), within 2 to 8 months postfracture, volunteered for this study. Participants performed an STST on a force-plate-imbedded chair designed to identify individual limb contributions during an STST. Asymmetry magnitude during the STST was determined for each individual. In addition, mPPT and SCT were assessed and regression analyses were performed to determine the contribution of asymmetry to the variance in these physical function scores beyond other factors predicting function.

RESULTS

Demographic factors (sex, time since fracture, repair type, and body mass index) were not significantly related to function in this sample. Age, gait speed, knee extension strength, balance confidence, and functional self-report were each significantly related to both mPPT (r = 0.43-0.86) and SCT (r = 0.40-0.83), and were retained in the regression model. Included variables accounted for 83.4% of the variance in mPPT score, and asymmetry during the STST did not significantly contribute to explaining variability in mPPT (P = .23). Variables in the regression model accounted for 78.0% of the variance in SCT score, and STST asymmetry explained 7.1% (P < .005) of the variance in SCT score.

DISCUSSION

In this small sample, asymmetry contributed significantly to explaining the variability in SCT performance, but not mPPT score. The SCT requires greater unilateral strength and control than the battery of items that comprise the mPPT. This contributes to the disproportionate number of falls occurring during stair ambulation (>10% of all fall-related deaths), relative to the minimal time typically involved in stair negotiation. Our results indicate potential benefit to identifying injured limb asymmetries as they predict function in challenging, high-risk functional tasks after hip fracture.

CONCLUSION

Although gait speed is the best explanator of physical function in older adults after hip fracture, lower extremity asymmetry during an STST provides a unique contribution to explaining high-level ambulatory performance after hip fracture. Efforts to reduce weight-bearing asymmetry during rehabilitation following hip fracture may improve function and recovery.

The effect of time restricted visual sensory input on asymmetry of ground reaction force components in female children

The association between visual sensory and the asymmetry index of sit-to-stand ground reaction force characteristics is not fully understood. Therefore, the purpose of this study was to investigate asymmetry index of sit-to-stand ground reaction forces, their times-to-peak, vertical loading rate, impulses, and free moment in blind and sighted children. 15 female children with congenital blindness and 30 healthy girls with no visual impairments volunteered to participate in this study. The girls with congenital blindness were placed in one group and the girls with no visual impairments were randomly divided into two groups of 15. The two condition groups consisted of, one eyes open and the other, eyes closed. The participants in the eyes closed group were asked to close their eyes for 20 min before the test, whereas those in the eyes open group kept their eyes open. Kinematic and kinetic data were collected using an eight-camera motion analysis system synchronized with two force plates embedded in the floor. A MANOVA test was run for between-group comparisons. There were no distinctive biomechanical alternations in all axes of ground reaction forces and their times-to-peak, vertical loading rate, impulses and free moments in congenital blindness and eyes closed groups compared with the eyes open group. However, eyes closed was associated with increased total time and second phase duration of sit-to-stand performance by 69% (p = 0.008) and 62% (p = 0.008), respectively. These findings reveal that individuals who are visually restricted in the short term, do not develop stereotypical movement strategies for sit-to-stand.

Validity of Visual Assessment of Sit to Stand After Hip Fracture

BACKGROUND AND PURPOSE

When treating older adults post-hip fracture, physical therapists routinely assess the sit-to-stand (STS) task using observational analysis. Studies have demonstrated that significant movement asymmetries in ground reaction force production of the fractured lower limb persist during STS, even though individuals may rise independently. To date, the validity of therapist judgments of lower limb force during STS has not been addressed. The purpose of this observational cohort study was to determine the accuracy of physical therapists' observational assessments of STS for detecting the involved limb and its ground reaction force contribution in older adults post-hip fracture.

METHODS

Eighteen home health physical therapists assessed 10 videotapes of older adults post-hip fracture rising from sitting and judged the side of involvement and the amount of ground reaction force generated by the fractured lower limb. Each videotape was synchronized with its respective force data. A wide spectrum of asymmetry in rising was represented in the test videos. Before making these judgments, the therapists viewed a separate set of training videos and received instructions in the use of specific visual cues to assist with subsequent judgments.

RESULTS AND DISCUSSION

Therapists judged the involved side correctly 74% of the time. Mean accuracy in judging ground reaction force output was 39% across all therapists. Force symmetry did not significantly influence accuracy of force judgments. Inaccurate judgments of force may limit therapeutic intensity and minimize the potential for developing motor strategies that favor force production of the involved limb. Augmenting observational analysis of STS with quantitative data could assist in optimizing restorative function.

CONCLUSION

Judgments of lower limb ground reaction force output during STS based on observation alone are not valid and may need to be supplemented with quantitative data.

High-Intensity Multimodal Resistance Training Improves Muscle Function, Symmetry during a Sit-to-Stand Task, and Physical Function Following Hip Fracture

OBJECTIVES

Post rehabilitation, older adults with hip fracture display low vertical ground reaction force (vGRF) on the involved lower extremity during a sit-to-stand task and low physical function. The purpose of this study was to test whether muscle performance, involved side vGRF during a sit-to-stand task, and physical function improved following multimodal high-intensity resistance training, when initiated after usual care (2 to 6 months after hip fracture).

DESIGN

Case series study, 12 weeks extended high-intensity strength training intervention following hip fracture.

SETTING

University hospital outpatient facility.

PARTICIPANTS

Twenty-four community-dwelling older adults (mean age 78.4 years (SD 10.4), 16 female/8 male), 3.6 (SD 1.2) months post-hip fracture and discharged from physical therapy participated. Intervention/Measurement: All participants performed sit-to-stand tasks, muscle performance tests, and modified physical performance test (mPPT) before and after 12 weeks (3x/wk) of training. Variables were compared using paired t-tests.

RESULTS

The vGRF rate of force development (RFD) and magnitude of discrepancy between limb loading during rising phase of sit-to-stand task (AREA) variables improved post-training (RFD ratio = Pre: 0.78 - Post: 0.82, AREA ratio = Pre: 0.79 - Post: 0.86). Surgical leg extension power gains were large (~65%) while strength gains were moderate (~34%); yielding improved symmetry in both strength (Pre: 0.74 - Post: 0.88) and power (Pre: 0.75 - Post: 0.82). Physical function improved pre-training 25 (SD 5.2) to post training 30 (SD 4.3), (p < 0.001).

CONCLUSION

Unique to this study, participants recovering from hip fracture demonstrated improved symmetry in sit-to-stand vGRFs, muscle function, and physical function after training. However, a high percentage of patients continued to experience persistently low vGRF of the involved side compared to previous studies of healthy elderly controls. Developing alternative strategies to improve involved side vGRF may be warranted.

Type of surgery is associated with pain and walking difficulties among older people with previous hip fracture

AIM

The aim was to assess the level of lower body pain among people with previous femoral neck fracture, and whether the type of surgery was associated with pain and physical function a mean of 2 years after surgery.

METHODS

The study included 115 community-dwelling older adults aged 60 years and older with previous femoral neck fracture, and 31 reference subjects without previous lower limb injuries. A total of 30 patients had internal fixation surgery, 70 had hemiarthroplasty and 15 had total hip replacement. All patients had surgery in the same hospital and received typical inpatient rehabilitation. From 1.6 months to 7.5 years after the fracture, the patients underwent examination including clinical evaluation, measurements of pain in the lower body (visual analog scale), physical function (maximal walking speed, Timed Up & Go, Berg Balance Scale) and self-reported walking difficulties.

RESULTS

Hip fracture patients reported more pain (81 ± 88 mm) compared with the reference group (25 ± 39 mm, P = 0.004). Patients with internal fixation reported significantly more pain than the other study groups. Significantly more patients with internal fixation (53%) reported walking difficulties compared with patients who had hemiarthroplasty (29%, P = 0.028) or total hip replacement (13%, P = 0.018). No significant difference was observed in performance-based physical function between the fracture groups, but participants in the reference group had better physical function than any of the fracture groups.

CONCLUSIONS

Hip fracture patients treated with internal fixation experienced more pain and walking difficulties than the hemiarthroplasty and total hip replacement groups. Different types of surgical fixation might require different rehabilitation and pain management strategies after hip fracture. Geriatr Gerontol Int 2015; ●●: ●●-●●.