Weight-bearing asymmetries during Sit-To-Stand in patients with mild-to-moderate hip osteoarthritis

Impaired Perception of Body-Weight Distribution Marks Functional Mobility Problems in Patients Undergoing Total Hip Arthroplasty

Hip osteoarthritis and total hip arthroplasty imply damaged articular and periarticular structures responsible for proprioception, and this damage may impair the accurate perception of body-weight distribution. In this study, we investigated proprioceptive abilities and accuracy perceiving body-weight distribution in patients undergoing total hip arthroplasty, and we assessed the associations between these abilities and body perception accuracy with functional mobility testing in 20 patients scheduled for total hip arthroplasty and 20 age-matched healthy participants. We assessed (a) absolute error in hip joint position sense (AE-JPS), (b) absolute error in body-weight distribution (AE-BWD) during standing and sit-to-stand tasks with open and closed eyes, and (c) functional mobility with the Timed Up and Go Test (TUG). We assessed patients undergoing hip arthroplasty before (T0) and five days after their surgery (T1), while control participants underwent a single evaluation. Relative to controls, participants undergoing surgery showed higher AE-JPS at 15° of hip flexion at T0 (p = .003) and at T1 (p = .007), greater AE-BWD during sit-to-stand with open eyes at T1 (p = .014) and with closed eyes at both T0 (p = .014) and at T1 (p < .001), and worse TUG at both T0 (p = .009) and T1 (p < .001). AE-BWD during sit-to-stand with closed eyes positively correlated with TUG at T0 (r = 0.55, p = .011) and at T1 (r = 0.51, p = .027). These findings suggested that impairments in body-weight distribution perception were evident both before and immediately after total hip arthroplasty, suggesting that these impairments may regularly mark these patients' functional mobility problems.

Is increased trunk flexion in standing up related to muscle weakness or pain avoidance in individuals with unilateral knee pain; a simulation study

The 'Timed Up and Go' test (TUG) is a widely used clinical tool for assessing gait and balance, relying primarily on timing as a measure. However, there are more observable biomechanical compensation strategies within TUG that are indicative of underlying neuromuscular issues and movement priorities. In individuals with unilateral knee osteoarthritis, an increased trunk flexion during TUG is a common phenomenon, often attributed to muscle weakness and/or pain avoidance. Unfortunately, it is difficult to differentiate between these underlying causes using experimental studies alone. This study aimed to distinguish between muscle weakness and pain avoidance as contributing factors, using predictive neuromuscular simulations of the sit-to-walk movement. Muscle weakness was simulated by reducing the maximum isometric force of the vasti muscles (ranging from 20% to 60%), while pain avoidance was integrated as a movement objective, ensuring that peak knee load did not exceed predefined thresholds (2-4 times body weight). The simulations demonstrate that a decrease in muscular capacity led to greater trunk flexion, while pain avoidance led to slower movement speeds and altered muscle recruitments, but not to greater trunk flexion. Our predictive simulations thus indicate that increased trunk flexion is more likely the result of lack of muscular reserve rather than pain avoidance. These findings align with reported differences in kinematics and muscle activations between moderate and severe knee osteoarthritis patients, emphasizing the impact of severe muscle weakness in those with advanced knee osteoarthritis. The simulations offer valuable insights into the mechanisms behind altered movement strategies, potentially guiding more targeted treatment.

Novel subtype of coxitis knee associated with acetabular dysplasia of the hip: a case series

BACKGROUND

Multiple joint arthritis patterns require a comprehensive understanding to optimize patient management. This study aimed to present a patient cohort that deviated from known definitions of coxitis knee (CK), identifying and characterizing this atypical group.

METHODS

Patients undergoing both total hip arthroplasty and total knee arthroplasty between January 2008 and December 2018 were retrospectively reviewed. The patients were classified into a typical coxitis knee group (classic, long leg arthropathy, and windswept deformity) and an atypical coxitis knee group. Leg-length discrepancy, body mass index (BMI), and radiographic parameters of the groups were compared and analyzed.

RESULTS

A total of 31 patients were allocated to the typical coxitis knee group (n = 10), and atypical coxitis knee group (n = 21). In the atypical group, 27 hips were involved, of which 21 had acetabular dysplasia, 5 exhibited subchondral insufficiency fracture-like changes, and only 1 had classic osteoarthritis. Among the 27 knees undergoing total knee arthroplasty, 26 showed varus alignment, 1 was within the normal range, and none was valgus. Acetabular dysplasia involved ipsilateral (n = 1), contralateral (n = 14), and bilateral (n = 6) hips, showing atypical coxitis knee. Patients with acetabular dysplasia were more likely to exhibit atypical CK.

CONCLUSION

Most patients in the cohort displayed acetabular dysplasia and contralateral varus knees, constituting a pattern referred to as acetabular dysplasia-associated gonarthritis. Identifying this novel subtype may have important clinical implications for regions with high risk factors, where acetabular dysplasia and constitutional genu varum are prevalent.

Identifying Muscle Function-based Phenotypes Associated With Radiographic Progression of Secondary Hip Osteoarthritis

OBJECTIVE

The purposes of our study were to (1) identify muscle function-based clinical phenotypes in patients with hip osteoarthritis (OA) and (2) determine the association between those phenotypes and radiographic progression of hip OA.

DESIGN

Prospective cohort study.

SETTING

Clinical biomechanics laboratory of a university.

PARTICIPANTS

Fifty women patients with mild-to-moderate secondary hip OA (N=50) were recruited from the orthopedic department of a single institution.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Two-step cluster analyses were performed to classify the patients, using hip flexion, extension, abduction, and external/internal rotation muscle strength (cluster analysis 1); relative hip muscle strength to total hip strength (ie, hip muscle strength balance; cluster analysis 2); and both hip muscle strength and muscle strength balance (cluster analysis 3) as variables. The association between the phenotype and hip OA progression over 12 months (indicated by joint space width [JSW] >0.5 mm) was investigated by logistic regression analyses. Hip joint morphology, hip pain, gait speed, physical activity, Harris hip score, and SF-36 scores were compared between the phenotypes.

RESULTS

Radiographic progression of hip OA was observed in 42% of the patients. The patients were classified into 2 phenotypes in each of the 3 cluster analyses. The solution in cluster analyses 1 and 3 was similar, and high-function and low-function phenotypes were identified; however, no association was found between the phenotypes and hip OA progression. The phenotype 2-1 (high-risk phenotype) extracted in cluster analysis 2, which had relative muscle weakness in hip flexion and internal rotation, was associated with subsequent hip OA progression, even after adjusting for age and minimum JSW at baseline (adjusted odds ratio [95% confidence interval], 3.60 [1.07-12.05]; P=.039).

CONCLUSION

As preliminary findings, the phenotype based on hip muscle strength balance, rather than hip muscle strength, may be associated with hip OA progression.

Lower limb joint loading in patients with unilateral hip osteoarthritis during bipedal stance and the effect of total hip replacement

Osteoarthritis of the hip is a common condition that affects older adults. Total hip replacement is the end-stage treatment to relief pain and improve joint function. Little is known about the mechanical load distribution during the activity of bipedal stance, which is an important daily activity for older adults who need to rest more frequently. This study investigated the distribution of the hip and knee joint moments during bipedal stance in patients with unilateral hip osteoarthritis and how the distribution changed 1 year after total hip replacement. Kinematic and kinetic data from bipedal stance were recorded. External hip and knee adduction moments were calculated and load distribution over both limbs was calculated using the symmetry angle. Preoperatively, the non-affected limb carried 10% more body weight than the affected limb when standing on two legs. Moreover, the mean external hip and knee adduction moments of the non-affected limb were increased compared to the affected limb. At follow-up no significant differences were observed between the patients' limbs. Preoperative and postoperative changes in hip adduction moment were mainly explained by the combination of the vertical ground reaction force and the hip adduction angle. Stance width also explained changes in the hip and knee adduction moments of the affected leg. Furthermore, as with walking, bipedal standing also showed an asymmetric mechanical load distribution in patients with unilateral hip osteoarthritis. Overall, the findings suggest the need for preventive therapy concepts that focus not only on walking but also on optimizing stance towards a balanced load distribution of both legs.

Prediction of in vivo hip contact forces during common activities of daily living using a segment-based musculoskeletal model

Background: Quantifying in vivo hip muscle and contact forces during activities of daily living (ADL) provides valuable information for diagnosis and treatment of hip-related disorders. The objective of this study was to utilize Freebody, a segment-based musculoskeletal model, for the prediction of hip contact forces using a novel objective function during seven common ADLs and validate its performance against the publicly available HIP98 dataset. Methods: Marker data, ground reaction forces, and hip contact forces during slow, normal, and fast walking, stair ascent and descent, and standing up and sitting down were extracted for 3 subjects from the HIP98 dataset. A musculoskeletal anatomical dataset was scaled to match the dimensions of each subject, and muscle and hip contact forces were estimated by minimizing a novel objective function, which was the summation of the muscle stresses squared and body weight-normalised hip contact force. The accuracy of predictions were quantified using several metrics, and muscle forces were qualitatively compared to experimental EMGs in the literature. Results: FreeBody predicted the hip contact forces during the ADLs with encouraging accuracy: The root mean squared error of predictions were 44.0 ± 8.5, 47.4 ± 6.5, and 59.8 ± 7.1% BW during slow, normal, and fast walking, 44.2 ± 16.8% and 53.3 ± 12.2% BW for stair ascent and descent, and 31.8 ± 8.2% and 17.1 ± 5.0% BW for standing up and sitting down, respectively. The error in prediction of peak hip contact forces were 14-18%, 24-28%, 17-35% for slow, normal, and fast walking, 7-25% and 15-32% in stair ascent and descent, and around 10% for standing up and sitting down. The coefficient of determination was larger than 0.90 in all activities except in standing up (0.86 ± 0.08). Conclusion: This study has implemented a novel objective function in a segment-based musculoskeletal model, FreeBody, for the prediction of hip contact forces during a large range of ADLs. The model outputs compare favourably for all ADLs and are the best in standing up and sitting down, while muscle activation patterns are consistent with experimental EMGs from literature. This new objective function addresses one of the major limitations associated with musculoskeletal models in the literature, namely the high non-physiological predicted hip joint contact forces.

Relationship between Asymmetries and Functional Autonomy in Older Chilean Adults

The objectives of this study were: (a) to determine asymmetries, both lower limb (LL) and upper limb (UL), in Chilean older adults, and (b) to relate asymmetries to FA in both LL and UL. Forty-one older adults voluntarily participated in this study (mean ± standard deviation [SD]: age 72.0 ± 8.0 years, LL asymmetries 13.78 ± 14.87%, UL asymmetries 10.70 ± 8.85%, FA 40.35 ± 16.26 points). The variables were: (1) asymmetries of LL and UL, assessed through a force platform and handgrip, respectively; (2) FA, assessed through the Latin American Group for Maturity (GDLAM) and the GDLAM index of autonomy (GI) protocol. The relationship between the variables was performed through Spearman's correlation. The analysis showed that 39% of the participants presented asymmetries above 15% in the LL. Likewise, this 39% of older adults presented a lower FA than their peers with asymmetries below 15% in the LL (≤15%: 35.64 ± 12.26 points vs. >15%: 47.69 ± 19.23 points, p = 0.003). The analysis showed a small correlation between LL and GI asymmetries (r = 0.27, p = 0.07) and a small but negative correlation between UL and GI (r = -0.21). The mean values of asymmetries of both LL and UL are within 'normal' parameters. However, several older adults were identified as being at risk. In parallel, older adults who presented a higher level of asymmetries in LL showed a lower level of FA.

The Recovery of Weight-Bearing Symmetry After Total Hip Arthroplasty Is Activity-Dependent

This study aimed to characterize ipsilateral loading and return to weight-bearing symmetry (WBS) in patients undergoing total hip arthroplasty (THA) during activities of daily living (ADLs) using instrumented insoles. A prospective study in 25 THA patients was performed, which included controlled pre- and postoperative follow-ups in a single rehabilitation center of an orthopedic department. Ipsilateral loading and WBS of ADLs were measured with insoles in THA patients and in a healthy control group of 25 participants. Measurements in the THA group were performed at 4 different visits: a week pre-THA, within a week post-THA, 3–6 weeks post-THA, and 6–12 weeks post-THA, whereas the healthy control group was measured once. ADLs included standing comfortably, standing evenly, walking, and sit-to-stand-to-sit (StS) transitions. All ADLs were analyzed using discrete methods, and walking included a time-scale analysis to provide temporal insights in the ipsilateral loading and WBS waveforms. THA patients only improved beyond their pre-surgery levels while standing comfortably (ipsilateral loading and WBS, p < 0.05) and during StS transitions (WBS, p < 0.05). Nevertheless, patients improved upon their ipsilateral loading and WBS deficits observed within a week post-surgery across all investigated ADLs. Ipsilateral loading and WBS of THA patients were comparable to healthy participants at 6–12 weeks post-THA, except for ipsilateral loading during walking (p < 0.05) at the initial and terminal double-leg support period of the stance phase. Taken together, insole measurements allow for the quantification of ipsilateral loading and WBS deficits during ADLs, identifying differences between pre- and postoperative periods, and differentiating THA patients from healthy participants. However, post-THA measurements that lack pre-surgery assessments may not be sensitive to identifying patient-specific improvements in ipsilateral loading and WBS. Moreover, StS transitions and earlier follow-up time points should be considered an important clinical metric of biomechanical recovery after THA.

Individuals with Unilateral Mild-to-Moderate Hip Osteoarthritis Exhibit Lower Limb Kinematic Asymmetry during Walking But Not Sit-to-Stand

Asymmetry during gait is associated with the evolution of secondary osteoarthritis. Kinematic asymmetry has been reported in advanced stages of hip osteoarthritis but has not been evaluated in earlier stages of the disease or has it been directly compared with unilateral and bilateral hip osteoarthritis. Our objective was to evaluate within-group symmetry and compare between-group asymmetry for three-dimensional pelvis, hip, knee, and ankle kinematics during walking and sit-to-stand in individuals with unilateral mild-to-moderate hip OA, bilateral mild-to-moderate hip osteoarthritis, and healthy controls. Twelve individuals with unilateral mild-to-moderate hip OA, nine individuals with bilateral mild-to-moderate symptomatic and radiographic hip OA, and 21 age-comparable healthy controls underwent three-dimensional motion analysis during walking and sit-to-stand. Pelvis and lower limb joint angles were calculated using inverse kinematics and between-limb symmetry was assessed for each group. Any resulting asymmetries (most affected minus contralateral limb) were compared between groups. Participants with unilateral hip osteoarthritis exhibited significantly less hip extension (7.90°), knee flexion (4.72°), and anterior pelvic tilt (3.38°) on their affected limb compared with the contralateral limb during the stance phase of walking. Those with unilateral hip osteoarthritis were significantly more asymmetrical than controls for sagittal plane hip and pelvis angles. No significant asymmetries were detected within- or between-groups for sit-to-stand. Individuals with unilateral hip osteoarthritis exhibited lower limb asymmetries consistent with those reported in advanced stages of disease during walking, but not sit-to-stand. Consideration of the possible negative effects of gait asymmetry on the health of the affected and other compensating joints appears warranted in the management of hip OA.

Compensation due to age-related decline in sit-to-stand and sit-to-walk

Capacity is the physiological ability of the neuromusculoskeletal systems; this declines with age. This decline in capacity may result in the inability to stand up (sit-to-stand, sit-to-walk), which is an important movement for independent living. Compensation, as a result of functional redundancy, is key in understanding how much age-related decline can be tolerated before movement limitations arise. Yet, this topic has been underexposed in the biomechanics literature. The purpose of this systematic review was to approach the literature on sit-to-stand and sit-to-walk studies from the perspective of compensation and create an overview of our current understanding of compensation in standing up, identifying the limitations and providing future recommendations. A literature search was performed, using the keywords and their synonyms: strateg*(approach, technique, way)AND, sit-to-walk OR sit-to-stand OR rise (raise, arise, stand, stand-up) AND chair (seat). Inclusion criteria: full articles on biomechanics or motor control on sit-to-stand or sit-to-walk in healthy adults (<60y), healthy or frail elderly adults (>60y), and adults with osteoarthritis. The results show that the experimental set-ups and musculoskeletal models in STS and STW studies generally exclude compensation by using restricted protocols and simplifications. Moreover, factors are mostly analysed in isolation, excluding confounding causes within capacity and/or movement objectives which limits the generalization of the results. Future studies in the standing up task should consider to (1) determine the effect of varying arm push-off strategies, (2) focus on sit-to-walk, (3) determine the biomechanical implications of asymmetry, and (4)incorporate assessments of physical capacity as well as changes in psychological priorities.

How does transtrochanteric anterior rotational osteotomy change the dynamic three-dimensional intact ratio in hips with osteonecrosis of the femoral head?

BACKGROUND

The intact ratio (the ratio of the intact area of the femoral head) on a two-dimensional anteroposterior radiograph is associated with the prognosis of hips with osteonecrosis of the femoral head after transtrochanteric anterior rotational osteotomy. However, changes of the three-dimensional intact ratio during dynamic weight-bearing activity and correlation of the three-dimensional intact ratio with clinical scores are still unknown.

METHODS

Kinematics of eight hips with osteonecrosis of the femoral head that underwent anterior rotational osteotomy were analyzed using image-matching techniques during chair-rising and squatting preoperatively and postoperatively. Two types of dynamic three-dimensional intact ratios were examined, including the lunate covered area (IR_LC) and in vivo peak contact force vector intersected area (IR_FV). The static three-dimensional intact ratio in each octant of the femoral head was also examined.

FINDINGS

The mean Harris hip score significantly improved from 67 preoperatively to 90 postoperatively. During chair-rising rising/squatting, the mean IR_LC and IR_FV significantly increased from 42%/41% and 7%/4% preoperatively, to 66%/65% and 79%/77% postoperatively, respectively. IR_LC significantly changed during the motion whereas substantial postoperative IR_FV was maintained throughout the motion. Additionally, Harris hip score and the static three-dimensional intact ratio in the superolateral regions had significant positive correlations with both IR_LC and IR_FV.

INTERPRETATION

Hip kinematics affected IR_LC but not IR_FV, which suggests that substantial intact bone occupies the region in which peak contact forces are applied during deep hip flexion. Additionally, improving intact ratio in the superolateral region led to improvements in both IR_LC and IR_FV with favorable clinical scores.

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.

Sacroiliac joint degeneration is common in patients with end-stage hip osteoarthritis secondary to unilateral developmental dysplasia of the hip: Factors associated with its severity and laterality

BACKGROUND

The etiology of sacroiliac joint (SIJ) degeneration has not been fully elucidated, and there has been almost no report on the relevance between SIJ degeneration and hip osteoarthritis secondary to developmental dysplasia of the hip (DDH). We investigated factors associated with SIJ degeneration, specifically its laterality in patients with end-stage hip osteoarthritis secondary to unilateral DDH.

METHODS

We included 152 patients with end-stage unilateral hip osteoarthritis secondary to DDH who underwent primary THA between January 2008 and November 2015. SIJ degeneration was classified (type 0, no degenerative change, to type 3, ankyloses) using preoperative axial computed tomography. SIJ degeneration of the DDH (shorter leg) and contralateral (longer leg) sides was compared; differences in patient demographics and radiological parameters between SIJ degeneration of type 0 or 1 versus type 2 or 3 for the shorter and longer leg sides were analyzed.

RESULTS

SIJ on the longer leg side showed more degenerative changes (p < 0.001). Substantial SIJ degeneration or ankylosis (type 2 or 3) was observed on 62.5% of longer leg sides and 33.6% of shorter leg sides. Factors significantly associated with SIJ degeneration severity were percent hip subluxation and leg length discrepancy for the longer leg side and body weight and body mass index (BMI) for the shorter leg side. Patients with worse degeneration on the shorter leg side (9.9%) had significantly larger BMI and longer sagittal vertical axis, whereas patients with worse degeneration on the longer leg side (46.7%) had significantly longer leg length discrepancy.

CONCLUSION

Severe SIJ degeneration was common in patients with end-stage hip osteoarthritis secondary to unilateral DDH. Patients with worse SIJ degeneration on the longer leg side had more hip subluxation, whereas patients with worse SIJ degeneration on the shorter leg (DDH) side tended to have sagittal spinal imbalance and greater body weight with larger BMI.

Recovery of Lower Extremity Function in the Initial Year Following Periacetabular Osteotomy: A Single Subject Analysis

BACKGROUND

Little is known regarding how lower extremity joint function recovers in the 6 months following periacetabular osteotomy (PAO) for activities other than walking.

PURPOSE

Assess patient-reported outcomes, hip strength, lower extremity joint moments, and moment distributions during sit-to-stand in a female athlete during the one-year period following PAO.

METHODS

Patient-reported outcomes (i.e. hip and groin outcome score; HAGOS), hip strength, and lower extremity joint moments and contributions to peak support moment during the sit-to-stand were assessed pre-operatively and at 6 weeks, 12 weeks, 6 months, and 13 months following PAO.

RESULTS

HAGOS scores returned to normative ranges, however overall quality of life scores remained low. By 13-month muscle strength recovered to baseline values. Following surgery, peak support and hip extensor moments were higher on the non-surgical limb, but the contributions of hip, knee, and ankle to peak support moment did not change. On the surgical limb, while peak support moments were lower, the hip contributed less, and the knee contributed more. These asymmetric loading patterns gradually normalized over 1 yea-.

CONCLUSIONS

Asymmetric loading following PAO should be considered when developing rehabilitation plans following this surgery.

Movement quality evaluation and its correlation with recommended functional measures in hip osteoarthritis

OBJECTIVE

Hip osteoarthritis may cause compensational movement strategies that require extra physical and mental effort. Such aberrant functioning can be captured in movement quality evaluation. The objective of this study was to explore whether movement quality, evaluated as a multiperspective phenomenon, is reflected in commonly used and recommended functional measures in this group of patients.

METHODS

A cross-sectional study design was used. Baseline included 80 female and 21 male participants with hip osteoarthritis. Movement quality was evaluated by the Body Awareness Rating Scale-Movement Quality and Experience (BARS-MQE), part one, including 12 movement items. Correlation analyses (Pearson and Spearman) were performed to explore associations between BARS-MQE (sum score and single item scores), and scores on measures of physical capacity (Chair test, Stairs test, 6 minutes walking test; 6MWT), self-reported activity level (UCLA), function (HOOS subscales), pain during walking (NRS), self-efficacy (ASES) and health (EQ-5D-5L). Based on previous evidence, we hypothesized moderate associations between BARS-MQE and these measures.

RESULTS

BARS-MQE's sum score showed moderate associations with Stairs test, 6MWT and UCLA (r = -0.425 to 0.304) and weak associations (r = 0.29 to 0.12) with ASES Pain and Symptoms, HOOS ADL, Chair test, NRS, HOOS Pain and Sports, and EQ-5D-5L. No association was found between BARS-MQE and HOOS Symptoms and Quality of life. Movement quality in item 12, walking, demonstrated moderate or weak association with all included measures.

CONCLUSION

In this study of participants diagnosed with hip osteoarthritis, movement quality evaluated by BARS-MQE was moderately reflected in measures of physical capacity and activity, but weakly reflected in self-reported measures of health problems. With its particular dynamic procedure and inclusion of the whole moving person, movement quality evaluation by the BARS-MQE was shown to provide supplementary information on functioning, scarcely captured by the commonly used and recommended measures.

Beyond Limits: Unmasking Potential Through Movement Discovery

Beth E. Fisher, PT, PhD, FAPTA, is a physical therapist, educator, and scholar whose clinical career has been shaped by numerous observations and experiences of patients' remarkable potential to recover ideal movement capability. Currently, Dr Fisher is a Professor of Clinical Physical Therapy in the Division of Biokinesiology and Physical Therapy at the University of Southern California. She is Director of the Neuroplasticity and Imaging Laboratory, primarily using transcranial magnetic stimulation to investigate brain-behavior relationships during motor skill learning and motor control in both individuals without disabilities and individuals with neurologic disorders. Dr Fisher previously worked at Rancho Los Amigos Medical Center on the Adult Neurology and Brain Injury Services. During her years as a clinician and rehabilitation specialist, it was her greatest ambition to be a part of developing physical therapist interventions that would maximize neural and behavioral recovery in individuals with pathological conditions affecting the nervous system. Toward this goal, she has continued to consult and teach nationally and internationally on current concepts for the treatment of adults with neurological disorders. It has been her consistent clinical observation not only that patients are limited by impairments that result from their injury, but that movement abnormalities are in part the result of a patient's automatic, implicit tendency to "respond" to those impairments via compensation.

Functional movement compensations persist in individuals with hip osteoarthritis performing the five times sit-to-stand test 1 year after total hip arthroplasty

Background

Methods to quantify and evaluate function are important for development of specific rehabilitation interventions. This study aimed to evaluate functional movement compensation in individuals with hip osteoarthritis performing the five times sit-to-stand test and change following total hip arthroplasty. To this end, trajectories of the body’s center of mass in the medial-lateral and anterior-posterior dimensions were quantified prior to and 1 year after total hip arthroplasty and compared to a healthy control group.

Methods

Twenty-eight individuals with hip osteoarthritis and 21 matched healthy controls were enrolled in this prospective study. Within 1 month prior to and 1 year after total hip arthroplasty, performance on the five times sit-to-stand test was evaluated using three-dimensional motion analysis and perceived pain using a visual analog scale. The center of mass trajectories for the medial-lateral and the anterior-posterior dimensions were identified, and the area under the curve was calculated, respectively. Repeated measures ANOVA were used to evaluate differences in the area under the curve, between pre- and postoperative performance, and between participants with hip osteoarthritis and controls.

Results

Preoperatively, individuals with hip osteoarthritis displayed a larger contralateral shift (p < 0.001) and forward displacement of the center of mass (p = 0.022) compared to controls. After surgery, deviations in both dimensions were reduced (medial-lateral p = 0.013; anterior-posterior p = 0.009). However, as compared to controls, the contralateral shift of the center of mass remained larger (p = 0.010), indicative of persistent asymmetric limb loading. Perceived pain was significantly reduced postoperatively (p < 0.001).

Conclusions

By quantifying the center of mass trajectory during five times sit-to-stand test performance, functional movement compensations could be detected and evaluated over time. Prior to total hip arthroplasty, individuals with hip osteoarthritis presented with an increased contralateral shift and forward displacement of the center of mass, representing a strategy to reduce pain by unloading the affected hip and reducing required hip and knee extension moments. After surgery, individuals with total hip arthroplasty displayed a persistent increased contralateral shift as compared to controls. This finding has implications for rehabilitation, where more focus must be directed towards normalizing loading of the limbs.

Possible predictive formulas for quantitative and time-based estimation of muscle strength during motion

[Purpose] To examine the validity of the predictive formulas based on the angle information of the segment center of mass and moments of inertia, and to propose a joint moment estimation method. [Participants and Methods] Twenty nine young healthy adults were divided into two groups: the Creation group (20 adults) was needed to create the prediction formulas, and the Verification group (9 adults) was needed to verify the formulas. By monitoring the Creation group, the angular information from inertial motion sensors and moments of inertia of each limb were used to estimate actual ankle joint moment and knee joint moment. Thereafter, the actual joint moments was derived from the Verification group and compared to the predicted values via Pearson correlations. [Results] Good to excellent correlations were obtained between the actual joint moments of the two groups for most of the motions. [Conclusion] It is suggested that the predictive formulas created from the angle information of the segment center of mass and moments of inertia can be used for an approximate estimation of the lower limb joint moments in the sagittal plane and more clinically useful tools need to be considered in the future.

Muscle quality index and isometric strength in older adults with hip osteoarthritis

Background

Older adults with hip osteoarthritis (OA) suffer a progressive loss of muscle quality and strength, affecting their daily activities and quality of life. The purpose of this study is to compare the levels of isometric strength among older adults with and without hip OA and healthy young adults, and to determine the relationship between muscle quality index (MQI) and isometric strength.

Methods

Fourteen subjects with hip OA (65.6 ± 3.0 years), 18 healthy older adults (66.6 ± 6.5 years) and 32 young adults (20.7 ± 2.0 years) participated in the study. MQI, isometric muscle strength of the hip, ten time sit-to-stand tests, and body composition were measured.

Results

The MQI was lower in subjects with hip OA, with no significant differences between groups (p > 0.054). Subjects with OA produced significantly less isometric strength in hip extension (p < 0.001), flexion (p < 0.001), abduction (p < 0.05), adduction (p < 0.001), external (p < 0.05) and internal rotation (p < 0.05). Subjects with OA demonstrated longer time in the execution of the sit-to-stand test (p < 0.001) in comparison with healthy older and young adults. High correlations between MQI, sit-to-stand (r =  - 0.76, p < 0.01) and peak force during hip abduction (r = 0.78, p < 0.01) where found in subjects with OA. Moderate correlation between MQI and peak force during hip flexion (r = 0.55, p < 0.05) and external rotation (r = 0.61, p < 0.05) were found in the OA group.

Conclusions

Subjects with OA have lower MQI than old and young healthy controls. In subjects with OA, there was a significant relationship between isometric strength of hip muscles and performance on the sit-to-stand test and the MQI.

Individuals with mild-to-moderate hip osteoarthritis exhibit altered pelvis and hip kinematics during sit-to-stand

BACKGROUND

Performance of the sit-to-stand (STS) task is compromised in individuals with advanced hip osteoarthritis (OA). Understanding how STS performance is altered in individuals with mild-to-moderate hip OA may inform interventions to improve function and slow disease progression.

RESEARCH QUESTION

Do trunk, pelvis, and hip biomechanics differ during a STS task between individuals with mild-to-moderate hip OA and a healthy, age-matched control group?

METHODS

Thirteen individuals with mild-to-moderate symptomatic and radiographic hip OA and seventeen healthy, age-matched controls performed a standardized STS task. Data were acquired using a three-dimensional motion capture system. The primary outcome measures were task duration, sagittal and frontal plane trunk, pelvis, and hip joint angles, and sagittal and frontal plane trunk and hip joint moments. Comparisons of lower-limb measures were between the most affected side in the hip OA group and a randomly chosen limb for the control group, termed the index limb, prior to and following lift-off from the chair.

RESULTS

Participants with mild-to-moderate hip OA took longer to perform the STS task compared to controls. Prior to lift-off, the hip OA group exhibited greater posterior pelvic tilt, greater pelvic rise on the index side and less hip joint flexion relative to controls. Following lift-off, the hip OA group exhibited greater pelvic rise on the index side compared to controls.

SIGNIFICANCE

Individuals with mild-to-moderate hip OA exhibit subtle alterations in movement strategy compared to healthy controls when completing a STS task similar, to a small extent, to adaptations reported in advanced stages of the disease. Interventions to target these features and prevent further decline in physical function may be warranted in the management of mild-to-moderate hip OA while the opportunity remains.

In-vivo elongation of anterior and posterior cruciate ligament in bi-cruciate retaining total knee arthroplasty

Anterior and posterior cruciate ligament (ACL and PCL) sacrifice in contemporary total knee arthroplasty (TKA) has been considered a potential factor leading to abnormal knee kinematics. Bi-cruciate retaining (BCR) TKA design allows retention of both ACL and PCL. However, there is a limited data on the ACL/PCL in-vivo elongation characteristics of BCR TKA. The study aimed to evaluate and compare the in-vivo elongation patterns of ACL/PCL between BCR TKA and contralateral non-implanted knee and to explore potential factors leading to the changed elongation patterns between limbs. ACL/PCL elongations of both knees during sit-to-stand were measured in 29 unilateral BCR TKA patients using a validated dual fluoroscopic tracking technique. Joint gap changes of the BCR TKA knees relative to the contralateral knee were quantified. BCR TKA and the contralateral non-implanted knee exhibited similar ACL elongation at extension and clinical anterior knee laxity. However, BCR TKA showed significantly greater PCL elongation during flexion than the non-implanted knee. Variation of changed elongation was observed for both ACL and PCL, suggesting a heterogeneous restoration of normal ACL/PCL functions. A significant correlation was found between extension joint gap change and the change of ACL elongation, highlighting the importance of precise joint line restoration and soft tissue balancing during BCR TKA surgery. Our findings suggest that BCR TKA did not fully restore "near-normal" cruciate ligament elongation patterns and anteroposterior stability. Considerable heterogeneity remains in the retained ligament elongation patterns and warrants further investigations of multifactorial factors to optimize ACL/PCL functions in BCR TKA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3239-3246, 2018.

Effect of hip joint angle at seat-off on hip joint contact force during sit-to-stand movement: a computer simulation study

Background

Sit-to-stand movements are a necessary part of daily life, and excessive mechanical stress on the articular cartilage has been reported to encourage the progression of osteoarthritis. Although a change in hip joint angle at seat-off may affect hip joint contact force during a sit-to-stand movement, the effect is unclear. This study aimed to examine the effect of the hip joint angle at seat-off on the hip joint contact force during a sit-to-stand movement by using a computer simulation.

Methods

A musculoskeletal model was created for the computer simulation, and eight muscles were attached to each lower limb. Various sit-to-stand movements were generated using parameters (e.g., seat height and time from seat-off to standing posture) reported by previous studies. The hip joint contact force for each sit-to-stand movement was calculated. Furthermore, the effect of the hip joint angle at seat-off on the hip joint contact force during the sit-to-stand movement was examined. In this study, as the changes to the musculoskeletal model parameters affect the hip joint contact force, a sensitivity analysis was conducted.

Results and conclusions

The hip joint contact force during the sit-to-stand movement increased approximately linearly as the hip flexion angle at the seat-off increased. Moreover, the normal sit-to-stand movement and the sit-to-stand movement yielding a minimum hip joint contact force were approximately equivalent. The effect of the changes to the musculoskeletal model parameters on the main findings of this study was minimal. Thus, the main findings are robust and may help prevent the progression of hip osteoarthritis by decreasing mechanical stress, which will be explored in future studies.

Electronic supplementary material

The online version of this article (10.1186/s12938-018-0610-5) contains supplementary material, which is available to authorized users.

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.

Balance performance in older adults with hip osteoarthritis: A systematic review

BACKGROUND

The hip is one of the most common joints affected by osteoarthritis (OA) and it has been identified as a key risk factors for falls. Physical impairments associated with OA, such as joint pain, muscle weakness, joint stiffness and sensory dysfunction, can all negatively affect balance and increase risk of falling.

QUESTION

Is balance performance altered in older adults with hip osteoarthritis? To determine whether static, dynamic, reactive or functional balance performance is altered in older people with hip osteoarthritis.

METHODS

Quantitative measures of postural control, including clinical and lab-based assessment of static, dynamic, reactive and/or functional balance performance, compared with a healthy control group or to the asymptomatic limb.

RESULTS

A total of 5407 articles were identified and 14 papers were included (10 with standardised mean different (SMD) data, four without SMD data). Based on data from single studies, there were medium/large effects for increased medio-lateral displacement when standing with eyes open, increased anterior-posterior and total sway path length when standing with eyes closed, greater overall instability when standing on an unstable surface, and increased displacement toward the stance leg in a lateral step in hip OA compared with controls.

CONCLUSION

Balance impairments were identified in some measures, limiting the conclusions as to whether balance deficits are a problem in hip OA. Inconsistent findings suggest that balance may not be a primary contributor to increased falls risk in older adults with hip OA. Other factors, such as musculoskeletal deficits, may contribute to higher falls rate in this population.

Relationship between movement time and hip moment impulse in the sagittal plane during sit-to-stand movement: a combined experimental and computer simulation study

Background

The association between repetitive hip moment impulse and the progression of hip osteoarthritis is a recently recognized area of study. A sit-to-stand movement is essential for daily life and requires hip extension moment. Although a change in the sit-to-stand movement time may influence the hip moment impulse in the sagittal plane, this effect has not been examined. The purpose of this study was to clarify the relationship between sit-to-stand movement time and hip moment impulse in the sagittal plane.

Methods

Twenty subjects performed the sit-to-stand movement at a self-selected natural speed. The hip, knee, and ankle joint angles obtained from experimental trials were used to perform two computer simulations. In the first simulation, the actual sit-to-stand movement time obtained from the experiment was entered. In the second simulation, sit-to-stand movement times ranging from 0.5 to 4.0 s at intervals of 0.25 s were entered. Hip joint moments and hip moment impulses in the sagittal plane during sit-to-stand movements were calculated for both computer simulations.

Results and conclusions

The reliability of the simulation model was confirmed, as indicated by the similarities in the hip joint moment waveforms (r = 0.99) and the hip moment impulses in the sagittal plane between the first computer simulation and the experiment. In the second computer simulation, the hip moment impulse in the sagittal plane decreased with a decrease in the sit-to-stand movement time, although the peak hip extension moment increased with a decrease in the movement time. These findings clarify the association between the sit-to-stand movement time and hip moment impulse in the sagittal plane and may contribute to the prevention of the progression of hip osteoarthritis.

Leg loading during quiet standing and sit-to-stand movement for one year after total hip arthroplasty

BACKGROUND

The objective of the present study was to investigate loading of the operated leg during quiet standing and sit-to-stand (STS) movement for 1 year after total hip arthroplasty (THA).

METHODS

One hundred and fifty-eight patients with end-stage hip osteoarthritis (OA) who had undergone unilateral primary THA participated in this study. The load distribution on the operated and non-operated legs was computed by measuring the vertical reaction force of the operated and non-operated legs during quiet standing and STS movement. We investigated the load distribution using Pressure Distribution Measurement Platform preoperatively and 1, 2, 3, 6, and 12 months postoperatively.

FINDINGS

Loading of the operated leg during quiet standing was restored 1 month postoperatively. Loading of the operated leg during STS movement was higher within 2 months postoperatively than the preoperative levels and continued to increase 1 year postoperatively. Loading of the operated leg was lower during STS movement than that during quiet standing, even 1 year postoperatively.

INTERPRETATION

A longitudinal and dynamic assessment of loading of the operated leg after THA is clinically important, and the loading during STS movement might continue to increase for a year after THA.

Influence of weight bearing visual feedback on movement symmetry during sit to stand task

BACKGROUND

Weight-bearing asymmetry is common in individuals with hip osteoarthritis and after total hip arthroplasty. Including symmetry training to the rehabilitation programs may normalize movement strategies during dynamic tasks. The purpose of this study was to evaluate the immediate influences of real-time visual feedback of weight distribution on the interlimb movement symmetry during the sit-to-stand task, before and after total hip arthroplasty, and to determine whether physical impairments affect the response to visual feedback.

METHODS

Subjects before and after total hip arthroplasty participated in three- dimensional motion analysis. Subjects completed 3 trials of sit-to-stand task in two conditions; "without visual feedback" and "with visual feedback". Outcome measures were the interlimb symmetry of vertical ground reaction force, and joint kinematics and kinetics. Pain and strength of lower limbs were assessed.

FINDINGS

Compared to "without visual feedback" condition, subjects moved with greater symmetry of vertical ground reaction force and joint kinetics when visual feedback was received. However, subjects continued to demonstrate interlimb difference for joint kinetics and vertical ground reaction force in the visual feedback condition. The increase in symmetry was not strongly influenced by physical impairments and subjects before and after total hip arthroplasty responded similarly to the feedback.

INTERPRETATIONS

We concluded that in a single session, the visual feedback of weight bearing distribution had a positive immediate effect on movement symmetry during the sit-to-stand task. Future studies that assess long-term retention and functional benefits are warranted before visual feedback is incorporated in rehabilitation for this patient population.

Hip biomechanics during stair ascent and descent in people with and without hip osteoarthritis

Hip osteoarthritis (OA) is often associated with pain and impaired function. Understanding biomechanical alterations in patients with hip OA during challenging activities such as stair use is important to inform treatments. The aim of this study was to determine whether kinematics and kinetics during stair ambulation differed between people with hip OA and healthy controls. Fifteen participants with symptomatic and radiographic hip OA and 15 asymptomatic healthy controls underwent 3-D motion analysis during stair ascent and descent. Trunk, pelvis, and hip kinematics as well as hip kinetics were evaluated. Analyses were performed unadjusted and adjusted for speed and leg length. In both the unadjusted and adjusted analyses, participants with hip OA ascended stairs with less hip range of motion in all three planes and a lower peak external rotation moment compared to controls. In the unadjusted analysis, hip OA participants descended stairs with greater ipsilateral trunk lean, less sagittal plane range of motion, lower peak extension moment, lower peak external rotation moment, and greater hip adduction moment impulse compared to controls. In the adjusted results, peak internal rotation moment and hip adduction moment impulse were greater in hip OA participants compared to controls. Findings show that individuals with hip OA display limited range of hip joint movement, particularly during stair ascent, and overall indicate the use of strategies (e.g., trunk lean; lower peak external rotation moment; higher adduction moment impulse) that implicate altered hip abductor function. Future research is required to further understand the implications of these findings on hip OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1505-1514, 2017.

Abnormal Joint Moment Distributions and Functional Performance During Sit-to-Stand in Femoroacetabular Impingement Patients

BACKGROUND

Femoroacetabular impingement (FAI) is a morphological abnormality of the hip joint that causes pain when performing a mechanically demanding activity of daily living such as the sit-to-stand (STS) task. Previous studies have assessed lower extremity joint mechanics during an STS task in various pathologies, yet the STS task has not been studied in FAI patients.

OBJECTIVE

The objective of this study was to identify differences in joint kinetics and performance between FAI patients and healthy controls during a STS task. It was hypothesized that FAI patients would exhibit altered time needed to complete the STS task, as well as altered lower extremity biomechanics, when compared to healthy controls.

DESIGN

This was a cross-sectional cohort study.

SETTING

The study took place at a motion capture laboratory at an institutional orthopedic facility.

PARTICIPANTS

Biomechanical analysis was performed in 17 FAI patients and 31 age- and body mass index (BMI)-matched healthy controls during the STS task.

METHODS

Sagittal plane joint moments, total support moment (TSM), joint contributions to the TSM, and functional measures during the STS task were compared between groups.

MAIN OUTCOME MEASUREMENTS

Peak joint moments, TSM and joint contributions to the TSM were assessed during the STS task. In addition, the time to and value of the peak vertical ground reaction force (vGRF), limb symmetry index at peak vGRF, loading rate, and total time needed to perform the STS task were determined.

RESULTS

Compared to the control participants, the FAI patients exhibited worse Hip Disability and Osteoarthritis Outcome Score (HOOS) pain and function subscores. No group differences were observed in peak sagittal joint moments during the STS task. However, when compared to controls, the FAI patients demonstrated reduced knee joint contributions to the TSM. In addition, the FAI patients exhibited increased time needed to perform the STS task, increased time to reach peak vGRF, and reduced lower extremity loading rate during the STS task.

CONCLUSIONS

FAI patients demonstrated abnormal joint contributions to TSM and altered functional performance during the STS task. These altered movement patterns during the STS task may be compensatory mechanisms used by the FAI patients to reduce pain and to improve function.

LEVEL OF EVIDENCE

Not applicable.

Movement-Pattern Training to Improve Function in People With Chronic Hip Joint Pain: A Feasibility Randomized Clinical Trial

Study Design Feasibility randomized clinical trial. Background Rehabilitation may be an appropriate treatment strategy for patients with chronic hip joint pain; however, the evidence related to the effectiveness of rehabilitation is limited. Objectives To assess feasibility of performing a randomized clinical trial to investigate the effectiveness of movement-pattern training (MPT) to improve function in people with chronic hip joint pain. Methods Thirty-five patients with chronic hip joint pain were randomized into a treatment (MPT) group or a control (wait-list) group. The MPT program included 6 one-hour supervised sessions and incorporated (1) task-specific training for basic functional tasks and symptom-provoking tasks, and (2) strengthening of hip musculature. The wait-list group received no treatment. Primary outcomes for feasibility were patient retention and adherence. Secondary outcomes to assess treatment effects were patient-reported function (Hip disability and Osteoarthritis Outcome Score), lower extremity kinematics, and hip muscle strength. Results Retention rates did not differ between the MPT (89%) and wait-list groups (94%, P = 1.0). Sixteen of the 18 patients (89%) in the MPT group attended at least 80% of the treatment sessions. For the home exercise program, 89% of patients reported performing their home program at least once per day. Secondary outcomes support the rationale for conduct of a superiority randomized clinical trial. Conclusion Based on retention and adherence rates, a larger randomized clinical trial appears feasible and warranted to assess treatment effects more precisely. Data from this feasibility study will inform our future clinical trial. Level of Evidence Therapy, level 2b-. J Orthop Sports Phys Ther 2016;46(6):452-461. Epub 26 Apr 2016. doi:10.2519/jospt.2016.6279.

Do persons with asymmetric hip pain or radiographic hip OA have worse pain and structure outcomes in the knee opposite the more affected hip? Data from the Osteoarthritis Initiative

PURPOSE

To determine if asymmetry between hips in pain or radiographic osteoarthritis (RHOA) is associated with worse pain and joint space narrowing (JSN) at baseline and longitudinally in knees contralateral to more affected hips.

METHODS

We studied 279 participants in the Osteoarthritis Initiative with baseline asymmetry between hips in pain and 483 with asymmetry in RHOA none of whom had a hip replacement for ≥4 years after baseline. RHOA assessed from pelvis radiographs was categorized as none, possible or definite and hip pain on most days of a month in the past year as present/absent. Knee pain (WOMAC scale) and JSN (fixed flexion radiographs) were categorized as none, mild and moderate-severe. We compared knees contralateral and ipsilateral to more affected hips on baseline knee pain and JSN using clustered multinomial regression and on change in knee pain and JSN over 4-5 years using generalized linear and logistic estimating equations.

RESULTS

Knees contralateral to painful hips had less baseline pain ("moderate-severe" vs "none", relative risk ratio [RRR]: 0.39, 95% CI = 0.27-0.57), but greater baseline JSN ("moderate-severe" vs "none", RRR: 1.62, 95% CI = 1.09-2.38) and greater worsening of pain during follow-up (P = 0.001). Knees contralateral to hips with worse RHOA had nonsignificant trends for greater baseline JSN (P = 0.10) and JSN progression (P = 0.17).

CONCLUSION

These findings provide limited support for the hypothesis that early asymmetry in hip pain and RHOA is associated with worse pain and structural outcomes in knees contralateral to the more affected hip.

Dynamic hip kinematics in patients with hip osteoarthritis during weight-bearing activities

BACKGROUND

There is an interest in quantifying the hip kinematics of patients with end-stage hip disorders before total hip arthroplasty. The purpose of the present study was to obtain dynamic hip kinematics under four different conditions, including deep flexion and rotation, in patients with osteoarthritis of the hip.

METHODS

Continuous X-ray images were obtained in 14 patients during gait, chair-rising, squatting, and twisting, using a flat panel X-ray detector. These patients received computed tomography scan to generate virtual digitally reconstructed radiographs. The density-based digitally reconstructed radiographs were then compared with the serial X-ray images acquired using image correlations. These 3D-to-2D model-to-image registration techniques determined the 3D positions and orientations of the pelvis and femur during the movement cycle of each activity.

FINDINGS

For gait, chair-rising, and squatting, the maximum hip flexion angles averaged 22°, 64°, and 68°, respectively. The pelvis was tilted anteriorly by an average of around 7° during the full gait cycle. For chair-rising and squatting, the maximum absolute values of anterior/posterior pelvic tilt averaged 8°/17° and 6°/18°, respectively. Hip flexion showed maximum flexion angle on the way of movement due to further anterior pelvic tilt during both chair-rising and squatting. For twisting, the maximum absolute values of internal/external hip rotation averaged 3°/13°.

INTERPRETATION

Patients with hip osteoarthritis prior to total hip arthroplasty demonstrated the limited ranges of coordinated motion of the pelvis, femur, and hip joint during each activity, especially in deeply flexed and rotated postures.

Sit-To-Stand Biomechanics Before and After Total Hip Arthroplasty

The purpose of this study was to evaluate changes in movement patterns during a sit-to-stand (STS) task before and after total hip arthroplasty (THA), and to compare biomechanical outcomes after THA to a control group. Forty-five subjects who underwent THA and twenty-three healthy control subjects participated in three-dimensional motion analysis. Pre-operatively, subjects exhibited inter-limb movement asymmetries with lower vertical ground reaction force (VGRF) and smaller moments on the operated limb. Although there were significant improvements in movement symmetry 3 months after THA, patients continued to demonstrate lower VGRF and smaller moments on the operated limb compared to non-operated and to control limbs. Future studies should identify the contributions of physical impairments and the influence of surgical approach on STS biomechanics.

No effects of a 12-week supervised exercise therapy program on gait in patients with mild to moderate osteoarthritis: a secondary analysis of a randomized trial

Background

It is unknown whether gait biomechanics in hip osteoarthritis patients with mild to moderate symptoms change following exercise therapy interventions. The aim of the present study was to compare stance phase gait characteristics in hip osteoarthritis patients with mild to moderate symptoms participating in a randomized trial with two different interventions; patient education only or patient education followed by a 12-week supervised exercise therapy program.

Results

The study was conducted as a secondary analysis of a single-blinded randomized controlled trial. Patients aged 40 to 80 years, with hip osteoarthritis verified from self-reported pain and radiographic changes, were included. The final material comprised 23 patients (10 males/13 females, mean (SD) age 58.2 (10.02) years) in the patient education only group, and 22 patients (9 males/13 females, mean (SD) age 60.2 (9.49) years) in the patient education + exercise therapy group. Three-dimensional gait analysis was conducted at baseline and at four month follow-up. Sagittal and frontal plane joint angle displacement and external joint moments of the hip, knee and ankle were compared from a one-way analysis of covariance between the groups at follow-up, with baseline values as covariates (p < 0.05). No group differences were observed at the four-month follow-up in gait velocity, joint angle displacement, or moments. As the compliance in the exercise therapy group was inadequate, we calculated possible associations between the number of completed exercise sessions and change in each of the kinematic or kinetic variables. Associations were weak to neglible. Thus, the negative findings in this study cannot be explained from inadequate compliance alone, but most likely also suggest the exercise therapy program itself to be insufficient to engender gait alterations.

Conclusions

Adding a 12-week supervised exercise therapy program to patient education did not induce changes in our selected biomechanical variables during the stance phase of gait, even when adjusting for poor compliance. Thus, we did not find evidence to support our exercise therapy program to be an efficacious intervention to induce gait alterations in this population of hip osteoarthritis patients.

Trial registration

NCT00319423 at ClinicalTrials.gov (registration date 2006-04-26).

Chronic pain management in the obese patient: a focused review of key challenges and potential exercise solutions

In obese persons, general and specific musculoskeletal pain is common. Emerging evidence suggests that obesity modulates pain via several mechanisms such as mechanical loading, inflammation, and psychological status. Pain in obesity contributes to deterioration of physical ability, health-related quality of life, and functional dependence. We present the accumulating evidence showing the interrelationships of mechanical stress, inflammation, and psychological characteristics on pain. While acute exercise may transiently exacerbate pain symptoms, regular participation in exercise can lower pain severity or prevalence. Aerobic exercise, resistance exercise, or multimodal exercise programs (combination of the two types) can reduce joint pain in young and older obese adults in the range of 14%-71.4% depending on the study design and intervention used. While published attrition rates with regular exercise are high (∼50%), adherence to exercise may be enhanced with modification to exercise including the accumulation of several exercise bouts rather than one long session, reducing joint range of motion, and replacing impact with nonimpact activity. This field would benefit from rigorous comparative efficacy studies of exercise intensity, frequency, and mode on specific and general musculoskeletal pain in young and older obese persons.

Validity of the Nintendo Wii Balance Board to assess weight bearing asymmetry during sit-to-stand and return-to-sit task

Weight bearing asymmetry is common in patients with unilateral lower limb musculoskeletal pathologies. The Nintendo Wii Balance Board (WBB) has been suggested as a low-cost and widely-available tool to measure weight bearing asymmetry in a clinical environment; however no study has evaluated the validity of this tool during dynamic tasks. Therefore, the purpose of this study was to determine the concurrent validity of force measurements acquired from the WBB as compared to laboratory force plates. Thirty-five individuals before, or within 1 year of total joint arthroplasty performed a sit-to-stand and return-to-sit task in two conditions. First, subjects performed the task with both feet placed on a single WBB. Second, the task was repeated with each foot placed on an individual laboratory force plate. Peak vertical ground reaction force (VGRF) under each foot and the inter-limb symmetry ratio were calculated. Validity was examined using Intraclass Correlation Coefficients (ICC), regression analysis, 95% limits of agreement and Bland-Altman plots. Force plates and the WBB exhibited excellent agreement for all outcome measurements (ICC=0.83-0.99). Bland-Altman plots showed no obvious relationship between the difference and the mean for the peak VGRF, but there was a consistent trend in which VGRF on the unaffected side was lower and VGRF on the affected side was higher when using the WBB. However, these consistent biases can be adjusted for by utilizing regression equations that estimate the force plate values based on the WBB force. The WBB may serve as a valid, suitable, and low-cost alternative to expensive, laboratory force plates for measuring weight bearing asymmetry in clinical settings.