The role of muscle weakness in the pathogenesis of osteoarthritis

Investigation of hip abductor activation in subjects with clinical unilateral hip osteoarthritis

OBJECTIVES

(a) To compare the magnitude of gluteus medius and tensor fascia lata activation between a group of subjects with clinical unilateral hip osteoarthritis and a group of healthy older adults. (b) To compare the magnitude of activation of the gluteus medius and tensor fascia lata between sides in a group of subjects with clinical unilateral hip osteoarthritis and a group of healthy older adults.

METHODS

19 subjects with clinical unilateral hip osteoarthritis and 19 healthy controls were investigated. The subjects performed a stepping task during which recordings were obtained using surface electromyograms from the hip abductors, and kinetic data were obtained from a dual force platform.

RESULTS

Subjects with clinical hip osteoarthritis had higher gluteus medius activation than the healthy older adults (p=0.037). In addition, there were no differences in the magnitude of gluteus medius activation between the sides (p=0.733). There was no difference in the force platform data between the groups (p=0.078).

CONCLUSIONS

The increased magnitude of gluteus medius activation in the group with hip osteoarthritis is evidence of a muscular dysfunction associated with hip disease. This has implications for the progressive nature of the disease and for its conservative management.

Delayed onset of quadriceps activity and altered knee joint kinematics during stair stepping in individuals with knee osteoarthritis

OBJECTIVE

To determine if the electromyographic onset of vastus lateralis and kinematic knee joint motion in individuals with knee osteoarthritis (OA) differs from that of asymptomatic persons, during the task of stair stepping.

DESIGN

Cross-sectional.

SETTING

University laboratory in Australia.

PARTICIPANTS

Twenty-five participants with symptomatic knee OA and 33 asymptomatic controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Surface electromyography to determine the onset of vastus lateralis activity. Two-dimensional kinematic analysis of sagittal plane knee motion during stance phase of stair ascent and descent.

RESULTS

Participants with knee OA showed delayed onset of vastus lateralis activity during stair descent (P<.05) but not ascent. Both groups displayed a similar total range of knee motion. However, during stair descent, participants with OA had less knee flexion during early stance (P<.05) than controls.

CONCLUSION

Individuals with knee OA display altered quadriceps function and knee joint kinematics during stair descent. These impairments may have implications for force attenuation across the knee joint and warrant future investigation.

Evaluation of quadriceps strength and voluntary activation after unicompartmental arthroplasty for medial osteoarthritis of the knee

INTRODUCTION

In early and moderate stages of osteoarthritis (OA) of the knee, arthrogenous muscle inhibition (AMI) is an important factor for the initiation and the progression of the disease. Although AMI has been shown to be reduced after physiotherapeutical exercises resulting in significant improvements in disability, implantation of unicondylar knee arthroplasties is much provided in these stages of OA. Therefore, in the present study we investigate changes in quadriceps muscle after implantation of such prostheses as compared to physiotherapeutical treatment, alone.

METHODS

In eighteen patients with bilateral moderate knee OA, who were treated with unicondylar knee arthroplasty we investigated voluntary activation (VA) and maximum voluntary contraction (MVC) of the quadriceps femoris muscle. There were 7 males and 11 females, the mean age at time of operation was 67 years (range 58-76 years). Measurements on both sides were performed preoperatively and 18 months postoperatively using the twitch-interpolation technique.

RESULTS

Follow-up assessment revealed a significant VA and MVC increase in both the surgically treated knees and in the contralateral knees treated by physiotherapy alone. However, VA and MVC improvements were significantly higher in the operated on knees than in those treated by physiotherapy alone.

DISCUSSION

Both physiotherapeutical exercise and unicondylar knee replacements lead to an improvement of quadriceps motor function in knee OA. The greater improvement in knees with both knee replacement and physiotherapy might be related to the intraoperative removal of arthritic tissue in these knees.

The effect of insufficient quadriceps strength on gait after anterior cruciate ligament reconstruction

OBJECTIVE

To determine the effect of quadriceps strength and joint stability on gait patterns after anterior cruciate ligament injury and reconstruction.

DESIGN

Cross-sectional comparative study in which four groups underwent motion analysis with surface electromyography.

BACKGROUND

Individuals following anterior cruciate ligament rupture often demonstrate reduced knee angles and moments during the early stance phase of gait. Alterations in gait can neither be ascribed to instability nor to quadriceps weakness alone when both are present.

METHODS

Twenty-eight individuals with complete anterior cruciate ligament rupture (10 patients with acute rupture, 8 patients following reconstruction with quadriceps strength >90% of the uninvolved side [strong-anterior cruciate ligament reconstructed group], and 10 patients after reconstruction with quadriceps strength <80% of the uninvolved side [weak-anterior cruciate ligament reconstructed group]), and 10 uninjured subjects underwent an examination of their lower extremity to collect kinematics, kinetics, and electromyography during walking and jogging. Anterior cruciate ligament reconstruction was arthroscopically assisted and a double loop semitendinosis-gracilis autograft or allograft was used as a graft source. All reconstructed subjects had stable knees, full range of motion, and no effusion or pain at the time of testing (more than three months after surgery).

RESULTS

Knee angles and moments of the strong group were indistinguishable from the uninjured group during early stance of both walking and jogging. The weak subjects had reduced knee angles and moments during walking, and jogged similarly to the deficient subjects. Regression analysis revealed a significant effect between early stance phase knee angles and moments and quadriceps strength during both walking and jogging.

CONCLUSION

Inadequate quadriceps strength contributes to altered gait patterns following anterior cruciate ligament reconstruction.

RELEVANCE

Rapid strengthening following anterior cruciate ligament injury or reconstruction may contribute to a safe return to high-level activities.

Lifestyle changes in the management of osteoarthritis

Lifestyle changes are gaining increasing recognition in the management of osteoarthritis. In most guidelines advice on exercise and weight reduction is now given priority over pharmacological therapies. In view of the face validity, safety and cost-effectiveness of such measures this would seem appropriate. This chapter discusses the role of exercise therapy, weight reduction and footwear. The emphasis is on evidence for effectiveness, comparison of techniques available and maintenance of adherence with each lifestyle change. Because most of our knowledge surrounds management of knee osteoarthritis, this is the focus of our discussion, with reference being made to other sites as appropriate.

Physiological alterations of maximal voluntary quadriceps activation by changes of knee joint angle

The purpose of this study was to investigate the influence of different angles of the knee joint on voluntary activation of the quadriceps muscle, estimating the ability of a subject to activate a muscle maximally by means of voluntary contraction. Isometric torque measurement was performed on 6 healthy subjects in 5 degrees intervals between 30 degrees and 90 degrees of knee joint flexion. Superimposed twitches at maximal voluntary contraction (MVC) and at a level of 60% and 40% of the MVC were applied and the voluntary activation estimated. At between 30 degrees and 75 degrees of knee flexion, the maximal extension torque increased at an average rate of 2.67 +/- 0.6 Nm/degree, followed by a decline with further flexion. However, throughout the joint-angle range tested, voluntary activation increased on average by 0.37%/degree with a maximum at 90 degrees of flexion. Due to the influence of joint position it is not possible to generalize results obtained at the knee joint angle of 90 degrees of flexion, which is usually used for the quadriceps twitch-interpolation technique. Consequently, it is useful to investigate voluntary activation deficits in knee joint disorders at a range of knee joint angles that includes, in particular, the more extended joint angles used frequently during daily activity.

Osteoarthritis as a systemic disorder including stromal cell differentiation and lipid metabolism

For many years articular cartilage has been the focus of research aimed at improving understanding of and treatment for osteoarthritis. Although much is known about the tissue, research has had little success in elucidating the pathogenesis of generalised osteoarthritis. A new hypothesis is required. Substantial changes in many tissues, including bone, muscle, ligaments, and joint capsule, as well as cartilage, are increasingly recognised in this disease, and not all these changes are localised to the affected joints. There is also a well established link with obesity. These observations, the common origins of the mesenchymal cells that maintain these tissues, and the possible role of neuroendocrine factors that can regulate bone mass, result in the hypothesis that systemic factors that include altered lipid metabolism could explain the diversity of physiological changes in generalised osteoarthritis. If proven, this hypothesis could have important implications for a new approach to pharmacological intervention in the early stages of the disease.

Movement and stability dysfunction--contemporary developments

A good understanding of the control processes used to maintain stability in functional movements is essential for clinicians who attempt to treat or manage musculoskeletal pain problems. There is evidence of muscle dysfunction related to the control of the movement system. There is a clear link between reduced proprioceptive input, altered slow motor unit recruitment and the development of chronic pain states. Dysfunction in the global and local muscle systems is presented to support the development of a system of classification of muscle function and development of dysfunction related to musculoskeletal pain. The global muscles control range of movement and alignment, and evidence of dysfunction is presented in terms of imbalance in recruitment and length between the global stability muscles and the global mobility muscles. Direction related restriction and compensation to maintain function is identified and related to pathology. The local stability muscles demonstrate evidence of failure of adequate segmental control in terms of allowing excessive uncontrolled translation or specific loss of cross-sectional area at the site of pathology. Motor recruitment deficits present as altered timing and patterns of recruitment. The evidence of local and global dysfunction allows the development of an integrated model of movement dysfunction.