Tim V. Wrigley

Hip strengthening reduces symptoms but not knee load in people with medial knee osteoarthritis and varus malalignment: a randomised controlled trial

OBJECTIVE To determine whether hip abductor and adductor muscle strengthening reduces medial compartment knee load and improves symptoms in people with medial tibiofemoral OA and varus malalignment. METHODS In a randomised controlled trial, 89 participants were randomly allocated to a hip strengthening group or to a control group with no intervention. The strengthening group performed a physiotherapist-supervised home exercise program targeting the hip abductor and adductor muscles for 12 weeks. The primary outcome was the peak external knee adduction moment measured using three-dimensional gait analysis by a blinded assessor. Secondary outcomes included a pain numeric rating scale, Western Ontario and McMaster Universities Osteoarthritis Index, step test, stair climb test, maximum isometric strength of hip and quadriceps muscles and participant-perceived rating of overall change. Intention-to-treat analyses were performed using linear regression modelling adjusting for baseline outcomes and other characteristics. RESULTS The trial was completed by 76/89 participants (85%). There was no significant between-group difference in change in the knee adduction moment [mean difference (95% confidence interval (CI)) 0.134 (-0.069 to 0.337) Nm/BW x HT%]. All pain, physical function and muscle strength measures showed significantly greater improvement in the strengthening group (all P<0.05). The relative risk (95% CI) of participant-perceived overall improvement in the strengthening group compared to the control group was 20.02 (6.21-64.47). CONCLUSIONS Although strengthening the hip muscles improved symptoms and function in this patient group, it did not affect medial knee load as measured by the knee adduction moment. Thus it is unlikely that hip muscle strengthening influences structural disease progression. TRIAL REGISTRATION ACTR12607000001493.

Does knee malalignment mediate the effects of quadriceps strengthening on knee adduction moment, pain, and function in medial knee osteoarthritis? A randomized controlled trial

OBJECTIVE To examine whether the effects of 12 weeks of quadriceps strengthening on the knee adduction moment, pain, and function in people with medial knee osteoarthritis (OA) differ in those with and without varus malalignment. METHODS A single-blind, randomized controlled trial of 107 community volunteers with medial knee OA was conducted. Participants were stratified according to knee malalignment (more varus or more neutral) and then randomized into either a 12-week supervised home-based quadriceps strengthening group or a control group with no intervention. The primary outcome was the knee adduction moment, measured using 3-dimensional gait analysis. Secondary outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index scores (measuring pain and physical function), step test score, stair climb test score, and maximum quadriceps isometric strength. Analyses of covariance were carried out based on intent-to-treat principles. RESULTS Quadriceps strengthening did not significantly alter the knee adduction moment in either the more malaligned or the more neutral group (unadjusted knee adduction moment 0.12 and 0.05% Nm/BWxHT, respectively). Function did not improve significantly following quadriceps strengthening in either alignment group, but there was a significant improvement in knee pain in the more neutrally aligned group (P < 0.001). CONCLUSION Quadriceps strengthening did not have any significant effect on the knee adduction moment in participants with either more varus or more neutral alignment. The benefits of quadriceps strengthening on pain were more evident in those with more neutral alignment. Knee alignment thus represents a local mechanical factor that can mediate symptomatic outcome from exercise interventions in knee OA.

Ground reaction forces, bone characteristics, and tibial stress fracture in male runners.

PURPOSE Tibial stress fracture is a common overuse running injury resulting from repetitive mechanical loading. This research project aimed to determine whether runners with a history of tibial stress fracture (TSF) differ in tibial bone geometry, tibial bone mass, and ground reaction force (GRF) parameters during running from those who have never sustained a stress fracture (NSF). METHODS Forty-six male running athletes (23 TSF; 23 NSF) ranging in age from 18 to 42 yr were recruited for this cross-sectional study. A force platform was used to measure selected GRF parameters (peak and time to peak for vertical impact force, vertical active force, and horizontal braking force) during running at 4.0 m x s(-1). Tibial bone geometry (cross-sectional dimensions and area) was calculated from a computerized tomography (CT) scan at the junction of the middle and distal thirds. Dual energy x-ray absorptiometry (DXA) provided measurements of tibial bone area, bone mineral content (BMC), and bone mineral density (BMD). RESULTS The TSF group had significantly smaller tibial cross-sectional area (P = 0.02) and DXA tibial bone area (P = 0.02), after adjusting for height and weight, than the NSF group. There were no significant differences between groups for GRF, tibial BMC, or tibial BMD. CONCLUSION These findings support the contention that bone geometry plays a role in stress fracture development and that male athletes with smaller bones in relation to body size are at greater risk for this bony injury.

Gait Modification Strategies for Altering Medial Knee Joint Load: A Systematic Review

To evaluate the effect of gait modification strategies on the external knee adduction moment (KAM), a marker of medial knee joint load; determine potentially adverse effects; assess the methodologic quality; and identify areas of future research.

Role of Muscle in the Genesis and Management of Knee Osteoarthritis

The muscles of the lower limb play an important role in the genesis and management of knee osteoarthritis (OA). This article outlines the influence of muscle activity on knee joint loading, the deficits in muscle function observed in people who have knee OA, and available evidence pertaining to the role of muscle in the development and progression of knee OA. It also discusses whether muscle deficits can be modified in knee OA and whether improvements in muscle function lead to improved symptoms and joint structure. It concludes with a discussion of exercise prescription for muscle rehabilitation in knee OA.

Lateral wedges in knee osteoarthritis: What are their immediate clinical and biomechanical effects and can these predict a three‐month clinical outcome?

OBJECTIVE To assess immediate effects of laterally wedged insoles on walking pain, external knee adduction moment, and static alignment, and whether these immediate effects together with age, body mass index, and disease severity predict clinical outcome after 3 months of wearing insoles in medial knee osteoarthritis. METHODS Forty volunteers (mean age 64.7 years, 16 men) were tested in random order with and without a pair of 5 degrees full-length lateral wedges. Immediate changes in static alignment were measured via radiographic mechanical axis and changes in adduction moment via 3-dimensional gait analysis. After 3 months of treatment with insoles, changes in pain and physical functioning were assessed via the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and patient-perceived global change scores. RESULTS Reductions in the adduction moment occurred with insoles (first peak mean [95% confidence intervals (95% CI)] -0.22 [-0.28, -0.15] Nm/body weight x height %), accompanied by a reduction in walking pain of approximately 24% (mean [95% CI] -1.0 [-4.0, 2.0]). Insoles had no mean effect on static alignment. Mean improvement in WOMAC pain (P = 0.004) and physical functioning (mean [95% CI] -6 [-11, -1]) was observed at 3 months, with 25 (69%) and 26 (72%) of 36 individuals reporting global improvement in pain and functioning, respectively. Regression analyses demonstrated that disease severity, baseline functioning, and magnitude of immediate change in walking pain and the first peak adduction moment with insoles were predictive of clinical outcome at 3 months. CONCLUSION Lateral wedges immediately reduced knee adduction moment and walking pain but had no effect on static alignment. Although some parameters predicted clinical outcome, these explained only one-third of the variance, suggesting that other unknown factors are also important.

A comparison of overground and treadmill running for measuring the three-dimensional kinematics of the lumbo-pelvic-hip complex.

OBJECTIVE To compare overground and treadmill running for differences in the three-dimensional angular kinematics of the lumbo-pelvic-hip complex. DESIGN A within-subject repeated measures design. BACKGROUND The treadmill is an attractive research instrument as speed and slope are easily controlled and the required calibration volume is reduced. However, the degree to which treadmill running simulates overground running has not been resolved in the literature to date. METHODS 10 able-bodied subjects ran overground and on a treadmill at a self-selected speed. The treadmill speed was matched to each subjects respective average overground speed. The time-distance and the three-dimensional angular kinematic data were captured using a passive marker based motion analysis system. A set of angular and temporal kinematic parameters were extracted from the data and subjected to statistical analyses. RESULTS Significant differences were found between overground and treadmill running for all the time-distance parameters. Despite this, the kinematics of the lumbar spine and pelvis were similar between the two running conditions, with only three parameters being significantly different. These were lumbar extension at initial contact, anterior pelvic tilt at initial contact and the first maximum anterior pelvic tilt. Hip flexion-extension parameters were also only found to display subtle differences. Of the 17 hip parameters analysed, only hip flexion at initial contact, maximum hip flexion at loading response, hip extension at toe off, maximum hip extension and hip flexion-extension range of motion were found to be significantly different. CONCLUSION A high powered treadmill with a minimal belt speed fluctuation is capable of being used to obtain a representation of the typical three-dimensional kinematic pattern of the lumbo-pelvic-hip complex during running. RELEVANCE In order for the treadmill to be accepted as a useful research and/or clinical assessment instrument, it must be demonstrated that it does not significantly alter the performance of the evaluated activity. In this respect, a treadmill with minimal intra-stride belt speed variability and similar surface stiffness to the relevant overground condition is likely to be capable of being used to obtain a representation of the typical human running action for well accommodated subjects.

Thoracic Kyphosis Affects Spinal Loads and Trunk Muscle Force

Background and Purpose Patients with increased thoracic curvature often come to physical therapists for management of spinal pain and disorders. Although treatment approaches are aimed at normalizing or minimizing progression of kyphosis, the biomechanical rationales remain unsubstantiated. Subjects Forty-four subjects (mean age [±SD]=62.3±7.1 years) were dichotomized into high kyphosis and low kyphosis groups. Methods Lateral standing radiographs and photographs were captured and then digitized. These data were input into biomechanical models to estimate net segmental loading from T2–L5 as well as trunk muscle forces. Results The high kyphosis group demonstrated significantly greater normalized flexion moments and net compression and shear forces. Trunk muscle forces also were significantly greater in the high kyphosis group. A strong relationship existed between thoracic curvature and net segmental loads (r =.85–.93) and between thoracic curvature and muscle forces (r =.70–.82). Discussion and Conclusion This study provides biomechanical evidence that increases in thoracic kyphosis are associated with significantly higher multisegmental spinal loads and trunk muscle forces in upright stance. These factors are likely to accelerate degenerative processes in spinal motion segments and contribute to the development of dysfunction and pain.

Feasibility of a gait retraining strategy for reducing knee joint loading: Increased trunk lean guided by real-time biofeedback

The purpose of this feasibility study was to examine changes in frontal plane knee and hip walking biomechanics following a gait retraining strategy focused on increasing lateral trunk lean and to quantify reports of difficulty and joint discomfort when performing such a gait modification. After undergoing a baseline analysis of normal walking, 9 young, healthy participants were trained to modify their gait to exhibit small (4°), medium (8°), and large (12°) amounts of lateral trunk lean. Training was guided by the use of real-time biofeedback of the actual trunk lean angle. Peak frontal plane external knee and hip joint moments were compared across conditions. Participants were asked to report the degree of difficulty and the presence of any joint discomfort for each amount of trunk lean modification. Small (4°), medium (8°), and large (12°) amounts of lateral trunk lean reduced the peak external knee adduction moment (KAM) by 7%, 21%, and 25%, respectively, though the peak KAM was only significantly less in the medium and large conditions (p<0.001). Increased trunk lean also significantly reduced the peak external hip adduction moments (p<0.001). All participants reported at least some difficulty performing the exaggerated trunk lean pattern and three participants reported ipsilateral knee, hip, and/or lower spine discomfort. Results from this study indicate that a gait pattern with increased lateral trunk lean can effectively reduce frontal plane joint moments. Though these findings have implications for pathological populations, learning this gait pattern was associated with some difficulty and joint discomfort.

Resistance exercise training increases muscle strength, endurance, and blood flow in patients with chronic heart failure.

Resistance exercise training was well tolerated in patients with stable, chronic heart failure, resulting in increased strength and endurance, and lower oxygen consumption at submaximum workloads but no improvement in VO2peak. There was also a significant increase in basal forearm blood flow following this form of exercise training.