Mechanisms of quadriceps muscle weakness in knee joint osteoarthritis: the effects of prolonged vibration on torque and muscle activation in osteoarthritic and healthy control subjects

Identifying yoga-based knee strengthening exercises using the knee adduction moment

BACKGROUND

This study aimed to compare muscle activations, co-contraction indices, and the knee adduction moment between static standing yoga postures to identify appropriate exercises for knee osteoarthritis.

METHODS

Healthy young women (24.4 (5.4) years, 23.1 (3.7) kg/m(2)) participated. Primary outcome variables were electromyographic activations of the vastus lateralis, rectus femoris, vastus medialis, biceps femoris, and semitendinosus; co-contraction between the biceps femoris and rectus femoris, and vastus lateralis and vastus medialis; and knee adduction moments of both legs during six static, standing yoga postures (two squatting postures, two lunging postures, a hamstring stretch, and a single-leg balance posture). A two-factor repeated measures analysis of variance was used to identify differences in muscle amplitudes, co-contractions, and knee adduction moment between postures and legs.

FINDINGS

Quadriceps activations were highest during squat and lunge postures (p≤0.001). Hamstring activations were highest during the hamstring stretch (p≤0.003). Squat and lunge postures produced higher co-contraction indices than other postures (p≤0.011). The wide legged squat (Goddess) and lunge with trunk upright (Warrior) produced the lowest knee adduction moments (p≤0.006), while the single-leg balance posture elicited a higher knee adduction moment than all other postures (p<0.05).

INTERPRETATION

Squatting and lunging postures could improve leg strength while potentially minimizing exposure to high knee adduction moments. Future work should evaluate whether these exercises are useful in people with knee osteoarthritis.

Effects of whole-body vibration training with quadriceps strengthening exercise on functioning and gait parameters in patients with medial compartment knee osteoarthritis: a randomised controlled preliminary study

OBJECTIVE

To compare the effects of whole-body vibration training (WBVT) with quadriceps strengthening exercise (QSE) with QSE alone on functioning and gait parameters in patients with medial compartment knee osteoarthritis.

DESIGN

Randomised controlled preliminary study.

SETTING

Department of Rehabilitation Medicine, West China Hospital, Chengdu, Sichuan, People's Republic of China.

SUBJECTS

Thirty-nine patients with medial compartment knee osteoarthritis.

INTERVENTIONS

Participants were assigned at random to one of two groups.

MAIN MEASURES

Visual analogue scale (VAS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), timed up and go test (TUG), 6-minute walk distance test (6MWD), and three-dimensional gait analysis during level walking at baseline, 12 weeks and 16 weeks (follow-up).

RESULTS

Compared with baseline, significant improvements in VAS, all WOMAC scales, TUG, 6MWD and all spatiotemporal parameters were seen in both the WBVT+QSE group and the QSE alone group at 12 and 16 weeks. However, the WBVT+QSE group showed greater improvements than the QSE alone group in WOMAC scales (physical function), TUG, 6MWD and cadence at 12 weeks. No differences were found between the WBVT+QSE and QSE alone groups in VAS, WOMAC scales (pain, stiffness), kinematic and kinetic gait parameters, and other spatiotemporal parameters at 12 weeks and 16 weeks.

CONCLUSION

Over a 3-month period, WBVT in combination with QSE improved symptoms, physical function and spatiotemporal parameters in patients with medial compartment knee osteoarthritis, and led to greater improvement than QSE alone in WOMAC scales (physical function), TUG, 6MWD and cadence.

Association between the severity of femoral condylar cartilage erosion related to knee osteoarthritis by ultrasonographic evaluation and the clinical symptoms and functions

OBJECTIVE

To determine the association between the severity of femoral condylar cartilage erosion resulting from knee osteoarthritis (OA) by an ultrasonographic grading system and the clinical symptoms and functions.

DESIGN

Cross-sectional study.

SETTING

A tertiary center.

PARTICIPANTS

Participants (N=101) with and without subjective complaints of knee discomfort were consecutively enrolled. Patients who had ever received knee arthroplasty, who had inflammatory arthritis, and whose knee flexion range of motion was <90° were excluded. A total of 194 knees were evaluated.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A semiquantitative ultrasonographic grading system was used to evaluate the severity of femoral condylar cartilage erosion. The clinical symptoms and functions were evaluated with the visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Lequesne index. The association of the VAS/WOMAC/Lequesne index with the ultrasonographic grading was assessed.

RESULTS

Positive linear associations were found between the ultrasonographic grading and the following: the VAS and the total scores and pain subscales of both the Lequesne index and WOMAC. Multivariate logistic regression analysis revealed grade-dependent association between VAS and ultrasonographic grading after adjusting for age, sex, and body mass index. The WOMAC and Lequesne index scores were associated with the ultrasonographic grading in more severe degrees, particularly in the pain subscales.

CONCLUSIONS

This semiquantitative ultrasonographic grading system may well reflect the clinical symptoms and functions related to knee OA as evaluated by the VAS, WOMAC, and Lequesne index. This method provides a more comprehensive description and measurement of knee OA.

Knee osteoarthritis: Clinical connections to articular cartilage structure and function

Articular cartilage is a unique biphasic material that supports a lifetime of compressive and shear forces across joints. When articular cartilage deteriorates, whether due to injury, wear and tear or normal aging, osteoarthritis and resultant pain can ensue. Understanding the basic science of the structure and biomechanics of articular cartilage can help clinicians guide their patients to appropriate activity and loading choices. The purpose of this article is to examine how articular cartilage structure and mechanics, may interact with risk factors to contribute to OA and how this interaction provides guidelines for intervention choices This paper will review the microstructure of articular cartilage, its mechanical properties and link this information to clinical decision making.

Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health

BACKGROUND

Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI).

FINDINGS

The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9).

CONCLUSIONS

All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans.

Immediate effects of electroacupuncture and manual acupuncture on pain, mobility and muscle strength in patients with knee osteoarthritis: a randomised controlled trial

OBJECTIVE

To compare the immediate effects of electroacupuncture and manual acupuncture on pain, mobility and muscle strength in patients with knee osteoarthritis.

METHODS

Sixty patients with knee osteoarthritis, with a pain intensity of ≥2 on the pain Numerical Rating Scale, were included. The patients were randomised into two groups: manual acupuncture and electroacupuncture. Pain intensity, degree of dysfunction (Timed Up and Go (TUG) test), maximal voluntary isometric contraction and pressure pain threshold were assessed before and after a single session of manual acupuncture or electroacupuncture treatments.

RESULTS

Both groups showed a significant reduction in pain intensity (p<0.001) and time to run the TUG test after the acupuncture treatment (p=0.005 for the manual acupuncture group and p=0.002 for the electroacupuncture group). There were no differences between the groups regarding pain intensity (p=0.25), TUG test (p=0.70), maximum voluntary isometric contraction (p=0.43) or pressure pain threshold (p=0.27).

CONCLUSIONS

This study found no difference between the immediate effects of a single session of manual acupuncture and electroacupuncture on pain, muscle strength and mobility in patients with knee osteoarthritis.

TRIAL REGISTRATION NUMBER

RBR-9TCN2X.

Biomechanical changes at the knee after lower limb fatigue in healthy young women

BACKGROUND

The purpose of this study was to identify changes in knee kinematics, kinetics and stiffness that occur during gait due to lower limb neuromuscular fatigue.

METHODS

Kinematic, kinetic and electromyographic measures of gait were collected on healthy, young women (n=20) before and after two bouts of fatigue. After baseline gait analysis, two bouts of fatiguing contractions were completed. Fatigue was induced using sets of 50 isotonic knee extensions and flexions at 50% of the peak torque during a maximum voluntary isometric contraction. Fatigue was defined as a drop in knee extension or flexion maximum voluntary isometric torques of at least 25% from baseline. Gait analyses were completed after each bout of fatigue. Dynamic knee stiffness was calculated as the change in knee flexion moment divided by the change in knee flexion angle from 3 to 15% of the gait cycle. Co-activations of the biceps femoris and rectus femoris muscles were calculated from 3 to 15% and 40 to 52% of gait. Repeated measures analyses of variance assessed differences in discrete gait measures, knee torques, and electromyography amplitudes between baseline and after each bout of fatigue.

FINDINGS

Fatigue decreased peak isometric torque. Fatigue did not alter knee adduction moments, knee flexion angles, dynamic knee stiffness, or muscle co-activation. Fatigue reduced the peak knee extension moment.

INTERPRETATION

While neuromuscular fatigue of the knee musculature alters the sagittal plane knee moment in healthy, young women during walking, high intensity fatigue is not consistent with known mechanical environments implicated in knee pathologies or injuries.

Osteoarthritis of the knee: why does exercise work? A qualitative study of the literature

The effectiveness of exercise to reduce pain and improve functioning in osteoarthritis of the knee (OAk) is well substantiated. Underlying mechanisms are still under debate and better understanding of the pathways involved may contribute to more targeted treatment strategies. The present qualitative analysis of the literature aims to provide an overview of theoretical models that are put forward to explain the beneficial treatment effects of exercise in OAk. An inductive qualitative approach, based on the 'grounded theory' of Glaser and Straus, was used. Twenty-two studies emphasizing on exercise therapy for OAk, collected from three Cochrane reviews and nine guidelines of the Physiotherapy Evidence Database (PEDRO) published between 2000 and 2012, were included. The introduction and discussion parts of these papers were screened for explanations of exercise-induced benefits in OAk patients. Seventy-three key points were identified which were subdivided into 16 core theoretical concepts. Finally, 5 categories were formed: neuromuscular, peri-articular, intra-articular, psychosocial components, and general fitness and health. We referred to scientific evidence that was used in the included studies to describe and categorize the concepts. Future research on exercise in OAk should allow distinguishing the contribution of different potential pathways to the treatment effects.

Muscle impairments in patients with knee osteoarthritis

Context:

Muscle impairments associated with knee osteoarthritis (OA) are the primary underlying cause of functional limitations. Understanding the extent of muscle impairments, its relationship with physical function and disease progression, and the evidence behind exercise therapy that targets muscle impairments is crucial.

Evidence Acquisition:

An electronic search for relevant articles using MEDLINE and CINHAL databases up to September 2011 was performed. In addition to the electronic search, retrieved articles were searched manually for relevant studies.

Results:

Quadriceps, hamstrings, and hip muscles are significantly impaired in subjects with knee OA compared with age-matched controls. Muscle strength, especially quadriceps, is a major determinant of both performance-based and self-reported physical function. Whether stronger quadriceps is protective against knee OA onset and progression is not clear. Exercise therapy, including global and targeted resistance training, is effective in reducing pain and improving function in subjects with knee OA.

Conclusions:

Subjects with knee OA have significant muscle impairments. These muscle impairments affect physical function and should be targeted in therapy. Further research is needed to explore the relationship between quadriceps strength and knee OA initiation and progression and to determine the optimal exercise prescription that augments outcomes in this patient population.