Quadriceps femoris muscle weakness and activation failure in patients with symptomatic knee osteoarthritis

Inter-rater reliability and test-retest reliability of the foot posture index (FPI-6) for assessing static foot posture in elderly female patients with knee osteoarthritis and its association with quadriceps muscle tone and stiffness

Objective

1. To assess the Inter-rater reliability and test-retest reliability of FPI-6 total score and individual scores in static foot posture evaluation among elderly female patients with knee osteoarthritis (KOA), aiming to establish the reliability of the FPI-6 scale. 2. To investigate the disparity between dominant and non-dominant quadriceps characteristics in elderly female KOA patients, as well as explore the correlation between quadriceps characteristics and abnormal foot posture, thereby offering novel insights for the prevention and treatment of KOA.

Methods

The study enrolled a total of 80 lower legs of 40 participants (all female) with unilateral or bilateral KOA, who were assessed by two raters at three different time points. The inter-rater and test-retest reliability of the FPI-6 was evaluated using the intra-class correlation coefficient (ICC), while the absolute reliability of FPI-6 was examined using the standard error of measurement (SEM), minimum detectable change (MDC), and Bland-Altman analysis. The internal consistency of FPI-6 was assessed using Spearman's correlation coefficient. Additionally, MyotonPRO was employed to assess quadriceps muscle tone and stiffness in all participants, and the association between quadriceps muscle tone/stiffness and the total score of FPI-6 was analyzed.

Result

Our study found excellent inter-rater and test-retest reliability (ICC values of 0.923 and 0.931, respectively) for the FPI-6 total score, as well as good to excellent reliability (ICC values ranging from 0.680 to 0.863 and 0.739-0.883) for individual items. The SEM and MDC values for the total score of FPI-6 among our study inter-rater were 0.78 and 2.15, respectively. and the SEM and MDC values for the test-retest total score of FPI-6 were found to be 0.76 and 2.11, respectively. Furthermore, the SEM and MDC values between inter-rater and test-retest across six individual items ranged from 0.30 to 0.56 and from 0.84 to 1.56. The Bland-Altman plots and respective 95% LOA showed no evidence of systematic bias. In terms of the mechanical properties of the quadriceps on both sides, the muscle tone and stiffness of rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) were significantly higher in the non-dominant leg compared to the dominant leg. Additionally, in the non-dominant leg, there was a significant positive correlation between the muscle tone and stiffness of VM, VL, RF and the total score of FPI-6. However, in the dominant leg, only VM's muscle tone and stiffness showed a significant positive correlation with the total score of FPI-6.

Conclusion

The reliability of the FPI-6 total score and its six individual items was good to excellent. Our findings offer a straightforward and dependable approach for researchers to assess foot posture in elderly female patients with KOA. Furthermore, we observed significantly greater quadriceps tension and stiffness in the non-dominant leg compared to the dominant leg. The FPI-6 total score exhibited a significant correlation with changes in quadriceps muscle performance among KOA patients. These observations regarding the relationship between changes in quadriceps muscle performance and foot posture in elderly female KOA patients may provide novel insights for disease prevention, treatment, and rehabilitation.

Compare the Quadriceps Activity between Mini-Midvastus and Mini-Medial Parapatellar Approach in Total Knee Arthroplasty with Electromyography

Background: The comparison between the mini-midvastus (mini-MV) and mini-parapatellar (mini-MPP) approach in total knee arthroplasty (TKA) remains a subject of debate. The present study compared quadriceps activation, pain levels, and clinical outcomes between the two approaches; quadricep activation was assessed using surface electromyography (sEMG). Methods: This retrospective cross-sectional study comprised a total of 78 patients aged between 50 and 85 years with primary osteoarthritis. Patients were divided into a mini-MV (n = 38) group and a mini-MPP (n = 40) group according to the surgical approach. Results: The two groups exhibited no significant differences in sEMG for the vastus medialis (VM) or rectus femoris (RF) at the follow-up time points, with the exception that the mini-MV group exhibited superior strength of RF during extensions at the 2-week follow-up. However, the mini-MPP group had superior Western Ontario and McMaster Universities Index (WOMAC) total and function scores at the 2- and 6-week follow-ups. The mini-MPP group also had superior WOMAC stiffness scores at the 2-week follow-up. The two groups did not differ significantly in terms of pain levels or morphine consumption. Conclusions: The sEMG data of quadriceps muscle would not differ significantly between the mini-MV and mini-MPP approaches for TKA. Moreover, the mini-MPP approach may yield superior WOMAC scores when compared with the mini-MV approach.

Can Arthrogenic Muscle Inhibition Exist in Peroneal Muscles Among People with Chronic Ankle Instability? A Cross-sectional Study

BACKGROUND

Ankle sprains lead to an unexplained reduction of ankle eversion strength, and arthrogenic muscle inhibition (AMI) in peroneal muscles is considered one of the underlying causes. This study aimed to observe the presence of AMI in peroneal muscles among people with chronic ankle instability (CAI).

METHODS

Sixty-three people with CAI and another sixty-three without CAI conducted maximal voluntary isometric contraction (MVIC) and superimposed burst (SIB) tests during ankle eversion, then fifteen people with CAI and fifteen without CAI were randomly invited to repeat the same tests to calculate the test-retest reliability. Electrical stimulation was applied to the peroneal muscles while the participants were performing MVIC, and the central activation ratio (CAR) was obtained by dividing MVIC torque by the sum of MVIC and SIB torques, representing the degree of AMI.

RESULTS

The intra-class correlation coefficients were 0.77 (0.45-0.92) and 0.92 (0.79-0.97) for the affected and unaffected limbs among people with CAI, and 0.97 (0.91-0.99) and 0.93 (0.82-0.97) for the controlled affected and unaffected limbs among people without CAI; Significant group × limb interaction was detected in the peroneal CAR (p = 0.008). The CARs were lower among people with CAI in the affected and unaffected limbs, compared with those without CAI (affected limb = 82.54 ± 9.46%, controlled affected limb = 94.64 ± 6.37%, p < 0.001; unaffected limb = 89.21 ± 8.04%, controlled unaffected limb = 94.93 ± 6.01%, p = 0.016). The CARs in the affected limbs were lower than those in the unaffected limbs among people with CAI (p = 0.023). No differences between limbs were found for CAR in the people without CAI (p = 0.10).

CONCLUSIONS

Bilateral AMI of peroneal muscles is observed among people with CAI. Their affected limbs have higher levels of AMI than the unaffected limbs.

Effects of blood flow restriction therapy in patients with knee osteoarthritis: protocol for an overview of systematic reviews

Background

Osteoarthritis (OA) is the most common and prevalent musculoskeletal disease associated with population aging, negatively impacting function and quality of life. A consequence of knee OA is quadriceps muscle weakness. Musculoskeletal rehabilitation using low load exercises, associated with Blood Flow Restriction (BFR) may be a useful alternative to high load exercises when those cannot be tolerated. Several systematic reviews have reported inconclusive results due to discrepancies in study findings, heterogeneity of results, evaluated time points, and research questions explored.

Objective

To perform an overview of systematic reviews with meta-analyses, synthesizing the most recent evidence on the effects of muscle strength training with BFR for knee OA.

Methodology

Systematic reviews that include primary controlled and randomized clinical trials will be considered for inclusion. Articles will be considered only if they present a clear and reproducible methodological structure, and when they clearly demonstrate that a critical analysis of the evidence was carried out using instrumented analysis. Narrative reviews, other types of review, overviews of systematic reviews, and diagnostic, prognostic and economic evaluation studies will be excluded. Studies must include adults aged 40 years and older with a diagnosis of knee OA. Two authors will perform an electronic search with guidance from an experienced librarian. The following databases will be searched: PubMed via MEDLINE, Embase, CENTRAL (Cochrane Central Register of Controlled Trials), PEDro, Cumulative Index to Nursing and Allied Health Literature (CINAHL) via EBSCO host, Web of Science, and the gray literature. The search strategy used in the databases will follow the acronym PICOS (population, intervention, comparison, outcome, and study design). Screening (i.e., titles and abstracts) of studies identified by the search strategy will be selected using Rayyan (http://rayyan.qcri.org). The quality assessment will be performed using the "Assessment of Multiple Systematic Reviews" (AMSTAR-2) tool.

Systematic Review Registration

PROSPERO, CRD42022367209.

Comparison of Pre- and Postoperative Motor-proprioceptive Abilities in Patients with Gonarthrosis

Both surgeons and patients want to achieve a high level of satisfaction and the best possible functional results within a short time after knee TEP surgery. By using a tool that digitally records various measurement parameters of balance and motor function preoperatively and postoperatively on a mobile basis and with little time expenditure, progressive results can be compared. Individual factors can thus be determined and these can influence the progress in regeneration and training progress perioperatively.In a prospective study, 100 patients before and 66 patients after installation of a cement-retained knee TEP were evaluated for the following parameters: balance, maximum strength, and power. All measurements were performed with the KMP measurement platform from MotoSana. The second measurements were performed in each case after a standardised follow-up treatment.It was shown that there are significant relationships between personal factors such as age, height, body weight and with baseline values and performance measures: maximum strength and power. Furthermore, it was shown that postoperative improvement could be achieved for the most part around balance support. All patients who previously had to hold on with one hand or both hands no longer needed support after surgery to maintain the single-leg stance for the specified time of 15 s. For a more detailed analysis of the balance parameters, the samples were adjusted and only the patients who did not hold on for support pre- and postoperatively were counted. In patients with low and medium initial stance, the sway area increased at the second measurement session, and in patients with large sway areas, it decreased, and the stance became more stable. In the area of maximum strength and power, patients with high baseline values still had higher values after AHB compared with the other patients, but lower values compared with their own baseline values.Patients who already had very good motor skills before surgery were able to achieve a greater increase in motor skills compared to the weaker group. However, all patients failed to reach their preoperative baseline values after completion of the AHB. Deficits in balance were still detectable in all groups. By using the presented force plate, measurement-based coordinated rehabilitation procedures are possible during and after completion of the AHB. Rehabilitation with individualised improvement of balance and motor function could be expected to prevent dissatisfaction after knee arthroplasty, e.g. due to muscular imbalance in femoropatellar pain syndromes.

Spatiotemporal and kinematic gait analysis in patients with knee osteoarthritis and femoral varus deformity

BACKGROUND

Knee osteoarthritis (OA) is commonly combined with the presentation of a coronal deformity of the knee. The bony origin of the knee varus deformity can be classified as tibial origin, femoral origin, or a combination of tibial and femoral causes. Deformities of tibial origin are mostly common clinically, while patients with knee OA with femoral varus deformity are less common.

RESEARCH QUESTION

Do hip, knee and ankle kinematics and spatiotemporal parameters differ between patients with knee OA with femoral varus deformity and healthy subjects?

METHODS

Twenty-five patients (14 females and 11 males) with knee OA and femoral varus deformity and 20 healthy subjects (12 males and 8 females) as control group were included in this study. The kinematic parameters of the hip-knee-ankle joint and spatiotemporal gait parameters were included in the study.

RESULTS

This study found that the step speed and step length of the knee OA with femoral varus (KOAF) group were smaller than those of the control group, while double support period percentage was greater in the KOAF group. Significant differences were found in the maximum knee extension angle, maximum knee flexion angle, knee flexion range of motion, maximum hip flexion angle, maximum hip extension angle, and hip flexion range of motion between the two groups. After comparing the ankle motion between the two groups, significant differences were found in the maximum eversion angle, inversion range of motion, maximum ankle abduction angle, and abduction range of motion.

SIGNIFICANCE

Knee OA with femoral varus deformity causes adaptive changes in the kinematic parameters of hip, knee and ankle joints and spatiotemporal gait parameters to alleviate symptoms and maintain normal activity.

Diverse parameters of ambulatory knee moments differ with medial knee osteoarthritis severity and are combinable into a severity index

Objective: To characterize ambulatory knee moments with respect to medial knee osteoarthritis (OA) severity comprehensively and to assess the possibility of developing a severity index combining knee moment parameters. Methods: Nine parameters (peak amplitudes) commonly used to quantify three-dimensional knee moments during walking were analyzed for 98 individuals (58.7 ± 9.2 years old, 1.69 ± 0.09 m, 76.9 ± 14.5 kg, 56% female), corresponding to three medial knee osteoarthritis severity groups: non-osteoarthritis (n = 22), mild osteoarthritis (n = 38) and severe osteoarthritis (n = 38). Multinomial logistic regression was used to create a severity index. Comparison and regression analyses were performed with respect to disease severity. Results: Six of the nine moment parameters differed statistically significantly among severity groups (p ≤ 0.039) and five reported statistically significant correlation with disease severity (0.23 ≤ |r| ≤ 0.59). The proposed severity index was highly reliable (ICC = 0.96) and statistically significantly different between the three groups (p < 0.001) as well as correlated with disease severity (r = 0.70). Conclusion: While medial knee osteoarthritis research has mostly focused on a few knee moment parameters, this study showed that other parameters differ with disease severity. In particular, it shed light on three parameters frequently disregarded in prior works. Another important finding is the possibility of combining the parameters into a severity index, which opens promising perspectives based on a single figure assessing the knee moments in their entirety. Although the proposed index was shown to be reliable and associated with disease severity, further research will be necessary particularly to assess its validity.

FUNCTIONAL OUTCOME OF PREOPERATIVE EXERCISES ON RANGE OF MOVEMENTS FOLLOWING TKA: A PROSPECTIVE COMPARITIVE STUDY

AIM Range of motion prior to TKRis a key determinant of the post-operative range of motion.The likelihood that the accompanying stiffness of the extensor mechanism will result in limited flexion following surgery increases with the preoperative range of motion.It would make sense to enhance knee ROM before surgery in order to optimize flexion following TKA.Comparisons were made between the patient groups who had knee surgery with preoperative exercises and those who had surgery without them. METHODS 156 patients with knee arthritis were collected over a period of 1.5years. They were divided into two groups. Pre-operative knee exercise was given to 78 patients for aone month. Prior to and following the test group's workouts, all patients were observed.All 156 underwent TKR, and their post-operative range of motion was evaluated at four weeks, three months, six months, and a year. We timed how long it took to fully extend and flex to 90 degrees. RESULTS Thisstudy suggested that the knee workouts were unquestionably helpful in achieving early knee flexion up to 90 in comparison to that of the control group. When the test group was compared to the control group, knee flexion to about 90 and more was attained in about 4 weeks; this difference was statistically significant (p 0.01).But after six months and a year of long-term follow-up, there were no discernible changes in the knee's range of motion. CONCLUSION Prehabilitation significantly improves the Knee Score for the intervention group both before surgery and three months after surgery. Exercises done before to surgery help patients recover more quickly from TKA and may speed up the process of achieving a good flexion and extension range of motion. However there is no significant difference in functional outcome after one year post surgery in both groups.

Toward Early and Objective Hand Osteoarthritis Detection by Using EMG during Grasps

The early and objective detection of hand pathologies is a field that still requires more research. One of the main signs of hand osteoarthritis (HOA) is joint degeneration, which causes loss of strength, among other symptoms. HOA is usually diagnosed with imaging and radiography, but the disease is in an advanced stage when HOA is observable by these methods. Some authors suggest that muscle tissue changes seem to occur before joint degeneration. We propose recording muscular activity to look for indicators of these changes that might help in early diagnosis. Muscular activity is often measured using electromyography (EMG), which consists of recording electrical muscle activity. The aim of this study is to study whether different EMG characteristics (zero crossing, wavelength, mean absolute value, muscle activity) via collection of forearm and hand EMG signals are feasible alternatives to the existing methods of detecting HOA patients' hand function. We used surface EMG to measure the electrical activity of the dominant hand's forearm muscles with 22 healthy subjects and 20 HOA patients performing maximum force during six representative grasp types (the most commonly used in ADLs). The EMG characteristics were used to identify discriminant functions to detect HOA. The results show that forearm muscles are significantly affected by HOA in EMG terms, with very high success rates (between 93.3% and 100%) in the discriminant analyses, which suggest that EMG can be used as a preliminary step towards confirmation with current HOA diagnostic techniques. Digit flexors during cylindrical grasp, thumb muscles during oblique palmar grasp, and wrist extensors and radial deviators during the intermediate power-precision grasp are good candidates to help detect HOA.

High tibiofemoral contact and muscle forces during gait are associated with radiographic knee OA progression over 3 years

BACKGROUND

The objective of this study was to investigate differences in tibiofemoral joint contact forces between individuals with moderate medial OA who exhibit radiographic knee OA progression within 3 years versus those who do not, and to understand the relationship between model-predicted contact forces and net external moments for this population.

METHODS

27 individuals with moderate medial compartment knee OA underwent baseline instrumented gait analysis. OA progressors were defined as those who experienced at least a one grade increase in medial joint space narrowing at three years. An electromyography-driven musculoskeletal model was used to estimate muscle and tibiofemoral contact forces at baseline, which were compared between progressors and non-progressors using t-tests.

RESULTS

Seven individuals experienced radiographic OA progression by 3 years. Progressors walked with significantly higher peaks of medial and total tibiofemoral contact forces, and higher impulse of medial contact forces. Significant and high correlations were found between: first peaks of medial and total contact forces with first peak of the knee adduction moment (R² = 0.74; R² = 0.59); second peaks of medial and total knee contact forces with second peaks of knee adduction and flexion moments (R² = 0.71; R² = 0.68); medial knee contact force impulse with knee adduction moment impulse (R² = 0.76).

CONCLUSIONS

Higher tibiofemoral joint contact forces during walking were associated with three-year radiographic knee OA progression based on medial joint space narrowing. These results support the need for strategies that reduce compressive knee contact forces through the reduction of adduction and flexion moments during walking.

Intrinsic foot muscle size and associations with strength, pain and foot-related disability in people with midfoot osteoarthritis

BACKGROUND

To compare intrinsic foot muscle size between people with and without symptomatic midfoot osteoarthritis, and examine the association between muscle size and strength, pain and foot-related disability.

METHODS

Twenty-three participants with symptomatic midfoot osteoarthritis and 23 age, sex and BMI matched controls were included. Intrinsic foot muscle cross-sectional area was measured using MRI. Hand-held dynamometry was used to assess foot and ankle muscle strength, and foot-related pain and disability was measured using Manchester Foot Pain & Disability Index.

FINDINGS

Small and non-statistically significant differences were found in intrinsic foot muscle cross-sectional area between the two groups (effect sizes 0.15-0.26, p > 0.05). Muscle strength was reduced in the midfoot osteoarthritis group, with differences of 12-33% (effect sizes 0.47-1.2). In the control group, moderate positive associations) existed between foot muscle cross-sectional area and lesser digits flexor strength (r = 0.5 to 0.7, p < 0.05). Conversely, in the midfoot osteoarthritis group, negligible positive associations were found (r < 0.3, p > 0.05). Associations between foot muscle cross-sectional with and pain and disability scores in the midfoot osteoarthritis group were negligible (r < -0.3, p > 0.05).

INTERPRETATION

Despite reductions in maximal isometric muscle strength, midfoot osteoarthritis does not appear to be associated with reduced intrinsic foot muscle cross-sectional area measured by MRI. Muscle compositional or neural factors may explain the reductions in muscle strength and variation in symptoms in people with midfoot osteoarthritis and should be investigated.

Contribution of lower extremity muscles to center of mass acceleration during walking: Effect of body weight

Overweight or obesity is known to be associated with altered activations of lower extremity muscles. Such changes in muscular function may lead to the development of mobility impairments or joint diseases. However, little is known about how individual lower extremity muscles contribute to the whole-body center of mass (COM) control during walking and the effect of body weight. This study examined the contribution of individual lower extremity muscle force to the COM accelerations during walking in overweight and non-overweight individuals. Musculoskeletal simulations were performed for the stance phase of walking with data collected from 11 overweight and 13 non-overweight adults to estimate lower extremity muscle forces and their contributions to the COM acceleration. Mean time-series data from each parameter were compared between body size groups using Statistical Parametric Mapping. Compared to the non-overweight group, the overweight group revealed a greater gastrocnemius contribution to the mediolateral (p = 0.006) and vertical (p < 0.001) COM accelerations during mid-stance, and had a lower vastus contribution to the anteroposterior COM acceleration (p < 0.001) during pre-swing. Increased contributions from the large posterior calf muscles to the mediolateral COM acceleration may be related to efforts to alleviate COM sway in overweight individuals.

Females with knee osteoarthritis use a detrimental knee loading strategy when squatting

BACKGROUND

The purpose of this study was to identify sex differences in lower limb kinematics, kinetics, and muscle activation patterns between individuals with osteoarthritis and healthy controls during a two-legged squat.

METHOD

Thirty OA (15 females) and 30 healthy (15 females) participants performed three 2-legged squats. Sagittal and frontal plane hip, knee, and ankle kinematics and kinetics were calculated. Two-way ANOVAs (Sex X OA Status) were used to characterize differences in squatting strategies between sexes and between those with and without knee OA.

RESULTS

A greater decrease in sagittal hip, knee, and ankle range of motion and knee joint power was observed in the OA participants compared to the healthy controls. Females with OA had significantly reduced hip and knee adduction angles compared to the healthy females and males with OA. Females also had decreased hip power, hip flexion, and hip adduction moments and knee adduction moments compared to their male counterparts, with the greatest deficits observed in the females with OA. Females with OA also had the highest magnitude of muscle activation for the quadriceps, hamstrings, and gastrocnemius throughout the squat, while males with OA showed increased activation of the vastus lateralis and medial gastrocnemius compared to the healthy males.

CONCLUSIONS

OA significantly altered biomechanics and neuromuscular control during the squat, with males employing a hip-dominant strategy, allowing them to achieve a greater lower limb range of motion.

Feasibility of a preoperative strengthening exercise program on postoperative function in patients undergoing hip or knee arthroplasty: a pilot randomized controlled trial

BACKGROUND

There are conflicting results on the effect of preoperative exercise programs on long-term function and little evidence on short-term function. The aim is to assess the feasibility of a preoperative strengthening exercise program in patients undergoing hip or knee joint arthroplasty in terms of trial design, recruitment, and follow-up rates.

METHODS

A randomized controlled feasibility study with patients undergoing hip or knee joint arthroplasty. Patients were randomized to a preoperative strengthening exercise program or standard of care. Feasibility outcome measures were recruitment rate (≥ 50%) and loss to follow-up (≤ 15%).

RESULTS

Of the 129 eligible participants, 63 participants consented to participate in the study (49%), and 27 were successfully randomized prior to surgery (43%). All 27 participants completed the baseline assessment. Of these, 6 (22%) had surgery during the exercise period. Of the remaining 21 participants, 20 (95%) completed the pre-surgery assessment. The study was terminated before five participants could be eligible for the 6-month assessment. Sixteen (76%) participants completed the 6-week post-surgery assessment. Twelve participants completed the 6-month assessment (75%).

CONCLUSION

Given the recruitment rate, randomization barriers, and study participant loss to follow-up, the study was discontinued since it was not considered feasible in this current form at our clinical site despite modifications made to the protocol. Future investigations into a modified intervention via telerehabilitation should be explored.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03483519 . Retrospectively registered in March 2018.

Risk Factors Associated with Cartilage Defects after Anterior Cruciate Ligament Rupture in Military Draftees

This study aimed to evaluate the different clinical results and factors associated with cartilage defects in military draftees who underwent different treatments after anterior cruciate ligament (ACL) rupture. Overall, 105 patients who had sustained ACL rupture were military draftees who underwent a conscription examination for physical status assessment from January 2012 to December 2020. Patients were divided into three groups: conservative treatment after ACL rupture, status post-anterior cruciate ligament reconstruction (ACLR), but graft rupture, and status post-ACLR with graft intact. Inter-group comparisons and statistical analyses were performed for age, body mass index (BMI), thigh circumference difference, side-to-side difference in anterior knee translation by KT-2000, meniscus tear, and cartilage defect. Multivariate logistic regression analysis was used to determine the factors associated with cartilage defects. The multivariable regression model showed that BMI (odds ratio OR: 1.303; 95% CI: 1.016–1.672; p = 0.037), thigh circumference difference (OR: 1.403; 95% CI: 1.003–1.084; p = 0.034), tear of lateral meniscus (LM) and medial meniscus (MM) (OR: 13.773; 95% CI: 1.354–140.09; p = 0.027), and graft rupture group (OR: 5.191; 95% CI: 1.388–19.419; p = 0.014) increased the risk of cartilage defects. There was no correlation between cartilage defects and age, KT-2000 difference, tear of LM or MM, or graft intact group. Progression of osteoarthritis was concerned after ACL rupture, and this study identified several factors of post-ACLR graft rupture, greater thigh circumference difference, BMI, and meniscus tear of both LM and MM affecting cartilage defects, which represent early degenerative osteoarthritis changes of the knee. The results of this study should be customized for rehabilitation and military training, especially in military draftees with ACL injuries.

Association between hamstring coactivation during isokinetic quadriceps strength testing and knee cartilage worsening over 24 months

OBJECTIVE

This study aimed to determine longitudinal associations, including sex-specific differences, between greater knee flexor antagonist coactivation and worsening cartilage morphology in knees with or at risk for osteoarthritis (OA).

DESIGN

Baseline measurements were collected at the 60-month visit of a longitudinal osteoarthritis study following community-dwelling participants (MOST). Knee flexor and extensor muscle activity were measured with surface electromyography during a maximal isokinetic knee extension task. MRI analyzed knee cartilage morphology at baseline and 24-month follow-up. Multivariable adjusted logistic regression models were used to assess associations between coactivation level and cartilage morphology worsening.

RESULTS

Analysis of 373 women (mean ± SD age 67.4 ± 7.3 years and BMI 29.7 ± 5.0 kg/m2) and 240 men (66.5 ± 7.8 years and 29.9 ± 4.5 kg/m2) revealed that women had greater medial (P < 0.001), lateral (P < 0.001), and combined (P < 0.001) hamstring coactivation than men. In both sexes, combined hamstring coactivation was associated with patellofemoral cartilage morphology worsening [1.23 (1.02, 1.49)] and to a less significant degree with whole knee cartilage morphology worsening [1.21 (0.98, 1.49)]. In men, greater combined hamstring coactivation was associated with increased risk for whole knee [1.59 (1.06, 2.39)] and patellofemoral [1.38 (1.01, 1.88)] cartilage morphology worsening and point estimates suggested association between medial hamstring coactivation and medial tibiofemoral cartilage morphology worsening. No significant associations were detected between greater hamstring coactivation and cartilage morphology worsening in women.

CONCLUSIONS

These findings suggest a longitudinal relationship between antagonist hamstring coactivation during isokinetic knee extensor testing and worsening of cartilage morphology over 24 months in men with or at risk for knee OA.

A Novel Mobile App-Based Neuromuscular Electrical Stimulation Therapy for Improvement of Knee Pain, Stiffness, and Function in Knee Osteoarthritis: A Randomized Trial

Background

Knee osteoarthritis (OA) is a widespread and debilitating disease that continues to plague patients. Over the past decade, neuromuscular electrical stimulation (NMES) therapy has shown promise in alleviating knee OA-related symptoms. This study sought to evaluate the efficacy and safety of a home-based NMES therapy for reduction of pain, stiffness, and function associated with knee OA.

Material and methods

A randomized, sham-controlled, double-blind, multicenter trial was conducted with 12-week follow-up in 156 knee OA patients receiving either home-based NMES therapy or a modified low-voltage NMES therapy. Outcome measures including knee pain, stiffness, and functionality were collected at baseline through week 12 after the therapy. The primary endpoint was the percentage change from baseline (PCFB) in the Visual Analog Scale (VAS) pain for a patient-nominated physical activity. Secondary endpoints included VAS for general knee pain, Western Ontario and McMaster Universities Osteoarthritis Index, Knee Injury and Osteoarthritis Outcome Score Joint Replacement, and isometric quadriceps strength test.

Results

A clinically meaningful reduction for VAS Nominated Activity was higher in the per-protocol treatment-compliant NMES group than that in the sham low-voltage NMES group at week 12 (PCFB of 42.8% vs 38.6%, P = .562). This was similarly true for the Western Ontario and McMaster Universities Osteoarthritis Index pain subscale (PCFBs of 36.8% vs 26.6%, P = .038). Similar trends and reductions of pain were observed for VAS General, Knee Injury and Osteoarthritis Outcome Score Joint Replacement Pain subscale, and isometric quadriceps strength.

Conclusion

Home-based NMES treatment resulted in a clinically meaningful reduction of knee pain, stiffness, and knee functional improvements at week 12 compared with sham NMES treatment.

The relationship between muscle capacity utilization during gait and pain in people with symptomatic knee osteoarthritis

BACKGROUND

Muscle capacity utilization reflects the percentage of maximal knee extensor strength required to complete physical activities.

RESEARCH QUESTION

Is pain associated with muscle capacity utilization during walking in older adults with knee osteoarthritis? Secondarily, is muscle capacity utilization in older adults with knee osteoarthritis sex-specific?

METHODS

Twenty-three participants (15 females) with symptomatic knee OA completed this study [age 67 ( ± 8) years, body mass index 29.7 ( ± 3.9) kg/m², gait speed during the Six Minute Walk test 1.25 ( ± 0.25) m/s]. Pain was measured using the Knee injury and Osteoarthritis Outcome Score. Muscle capacity utilization was quantified as the peak external knee flexor moment during level walking normalized to knee extensor maximum voluntary isometric contraction. The knee flexor moment was calculated from kinematic and kinetic data during barefoot level walking at a self-selected speed and at 1.1 m/s. Knee extensor maximum voluntary isometric contraction was measured on a dynamometer. Multiple linear regressions were used to determine the relationship between pain and muscle capacity utilization after adjusting for age, sex, body mass index, and gait speed. Independent sample t-tests examined sex differences.

RESULTS

Pain was not associated with muscle capacity utilization during self-selected and standardized walking speeds (p = 0.38 and p = 0.36, respectively). Females did not require a greater muscle capacity utilization than males to complete gait at self-selected and standardized speeds (p = 0.28, and p = 0.40, respectively).

SIGNIFICANCE

Muscle capacity utilization was not associated with pain during walking in people with knee osteoarthritis. Future work should explore more challenging activities of daily living in knee OA.

Impairment of electrical activation of wrist flexor and extensor muscles during gripping and functional activities in the early stage of hand osteoarthritis: A cross-sectional study

STUDY DESIGN

This is a cross-sectional study.

INTRODUCTION

The wrist extensor muscles have a fundamental role in the stabilization of the wrist while performing manual activities. However, it is unknown if the clinical signs of hand osteoarthritis (HOA) cause impairment in the activation of these muscles PURPOSE OF THE STUDY: The purpose of this study was to investigate whether early-stage HOA affects the magnitude of activation and coactivation between the wrist extensor and flexor muscles METHODS: Thirty-two subjects were divided into two groups: control group (n = 16; 55 ± 7.42 years) and a group with HOA grades 2 or 3 (HOAG; n = 16; 57 ± 7.82 years). Muscle activation was measured in m. flexor digitorum superficialis, m. flexor carpi ulnaris (FCU) and extensors (EXT) during the evaluation of grip strength and three manual activities (write, cut a paper with scissors, and close and open a bottle). The coactivation index was calculated between the electromyography of the flexors (FCU and FSD) and wrist EXT.

RESULTS

HOAG presented reduced muscle activation in all tasks, with a statistical difference for the flexor digitorum superficialis and EXT in the scissors activity, and for the FCU in the bottle activity. No differences were found between groups for the coactivation index and grip strength.

DISCUSSION

The reduced muscle activity may be due to an inability of the patients of the HOAG to recruit all motor units or to an inhibition related to the presence of pain.

CONCLUSION

In the early stages of HOA, there is a functional deficit associated with a reduced muscle activity of the wrist muscles during manual activities.

Are Medial and Lateral Tibiofemoral Compressive Forces Different in Uphill Compared to Level Walking for Patients Following Total Knee Arthroplasty?

The purpose of this study was to determine how tibiofemoral joint compressive forces and knee joint-spanning muscle forces during uphill walking change compared to level walking in patients with total knee arthroplasty (TKA). A musculoskeletal model capable of resolving total (TCF), medial (MCF), and lateral (LCF) tibiofemoral compressive forces was used to determine compressive forces and muscle forces during level and uphill walking on a 10 deg incline for twenty-five post-TKA patients. A 2 × 2 (slope: level and 10 deg × limb: replaced and nonreplaced) repeated measures analysis of variance was used to detect differences in knee contact forces between slope and limb conditions and their interaction. Peak loading-response TCF, MCF, and LCF were greater during uphill walking than level walking for nonreplaced limbs. During uphill walking, peak loading-response TCF was smaller in replaced limbs compared to nonreplaced limbs with no change in MCF or LCF. Peak knee extension moment and knee extensor muscle force were smaller in replaced limbs compared to nonreplaced limbs during uphill walking. During level walking, replaced and nonreplaced limbs experienced rather equal joint loading; however, replaced limb experienced reduced joint loading during uphill walking. Differences in joint loading between replaced and nonreplaced limbs were not present during level walking, suggesting compensation from the replaced limb during the more difficult task. Uphill walking following TKA promotes more balanced loading of replaced limbs during stance; however, these benefits may come at the expense of increased loading on nonreplaced limbs.

Anterior knee pain independently alters landing and jumping biomechanics

Background Biomechanical effects of anterior knee pain are difficult to distinguish from effects of other factors also related to knee injury (e.g., joint effusion). The purpose of this study was to evaluate independent effects of anterior knee pain on landing and jumping biomechanics. Methods Thirteen healthy participants performed a land and jump movement task, under three experimental conditions (pre-pain, pain, and post-pain), during one data collection session. One 1-ml injection of hypertonic saline into the infrapatellar fat pad was used to induce experimental anterior knee pain during the pain condition. Participant-perceived anterior knee pain was measured every 2 min throughout data collection. Landing and jumping biomechanics were measured and compared between the experimental conditions using a functional statistical approach. Findings The aforementioned injection increased mean participant-perceived anterior knee pain, from zero during the pre-pain condition to 2.6 ± 0.71 cm during the pain condition. Vertical ground reaction force, knee flexion angle, and internal knee extension moment decreased by approximately 0.100 body weights, 3°, and 0.010 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Conversely, hip flexion angle and internal hip extension moment increased by approximately 3° and 0.006 Nm/body weight × body height, respectively, between the pre-pain and pain conditions. Several biomechanical changes persisted after anterior knee pain abatement (the post-pain condition). Interpretation Anterior knee pain alters landing and jumping biomechanics, independent of other injury-related factors. These altered biomechanics likely change knee joint loading patterns and might increase risk for chronic knee joint injury and/or pathology.

Adherence to Neuromuscular Electrical Stimulation Interventions for Muscle Impairment in Hip and Knee Osteoarthritis: A Systematic Review

Background

Neuromuscular electrical stimulation (NMES) provides a promising approach to counteract muscle impairment in hip and knee osteoarthritis, and to expedite recovery from joint replacement surgery. Nonetheless, application into clinical orthopaedic practice remains limited, partly due to concerns regarding patient tolerance.

Objectives

This systematic review aimed to quantify levels of adherence to NMES interventions for muscle impairment in hip and knee osteoarthritis and identify strategies to increase compliance.

Data Sources

Randomised controlled trials (RCTs) were identified in a web-based literature review, completed in December 2020. The databases sourced included the Cochrane Library, CINAHL Complete, Medline Complete and PubMed.

Eligibility Criteria

Studies were included if they were: (i) conducted in cohorts of adults with hip or knee osteoarthritis; (ii) a protocol of electrical muscle stimulation prescribed to treat muscle impairment; and (iii) reported intervention adherence or attrition rate. Data were extracted on adherence rate, reasons for non-adherence and potential strategies to increase adherence. Risk of bias was assessed using the Physiotherapy Evidence Database (PEDro) scale.

Results

The search yielded 120 articles, of which 15 studies were considered eligible and included in the analysis (n = 922). All NMES treatment was applied to the quadriceps, with 1 study targeting the quadriceps and calves. The mean PEDRO score of the included studies was 6.80 out of a possible 10 (range 6-8). Mean adherence did not differ between groups receiving treatment with NMES (85% ± 12%) and control groups receiving voluntary exercise or education (84% ± 9%) (P = .97). Reasons for non-adherence or attrition included a dislike of the device, dizziness, pain and discomfort. Strategies to increase adherence included NMES education, a familiarisation period, supervision, setting thresholds based upon patient tolerance, monitoring pain levels during stimulation and using built-in adherence trackers.

Conclusions

This systematic review indicates that adherence to NMES interventions for muscle impairment in hip and knee osteoarthritis in clinical trials does not differ to control groups receiving education or voluntary exercise, and hence should not be a barrier to application in clinical practice.

Effects of TheraBand and Theratube Eccentric Exercises on Quadriceps Muscle Strength and Muscle Mass in Young Adults

Purpose

This study was aimed at comparing the effects of TheraBand and theratube eccentric exercises on quadriceps muscle strength in young adults.

Methods

Thirty young adults (19 females, 11 males) participated in this pretest-posttest experimental study. Participants were randomly assigned to one of the two groups: TheraBand and theratube groups. They received the training intervention 3 times a week for 4 weeks (12 sessions) with progression after 2 weeks. Maximum eccentric quadriceps strength was assessed using the Biodex isokinetic dynamometer system. Additionally, quadriceps muscle mass was measured using a tape.

Results

Both groups showed a significant improvement in the peak torque of the eccentric isokinetic quadriceps' strength after weeks 2 and 4. Strength change in the quadriceps was nonsignificant in the theratube group compared to the TheraBand group after 4 weeks of training (p < 0.05). There was no increase in muscle mass during the 4 weeks of training in any group (p > 0.05).

Conclusion

Both the TheraBand and theratube are equally effective in the strengthening of the quadriceps muscle in young adults. Therefore, either the TheraBand or theratube may be used according to the availability and feasibility of the subjects for training intervention.

[Possibilities and limits of conservative treatment for osteoarthritis : Sport advice, training therapy, orthotics and cartilage therapeutics]

Hintergrund

Arthrose – die Degeneration von Gelenken – ist ein weit verbreitetes Problem durch alle Bevölkerungsschichten, das im zunehmenden Alter vermehrt auftritt und die häufigste Ursache für mobilitätseinschränkende Schmerzen am Bewegungsapparat ist. Etwa 70–80 % der über 70-Jährigen zeigen Zeichen einer Gelenksdegeneration. Insgesamt sind bis zu 25 % der Gesamtbevölkerung davon betroffen, aufgrund der generellen Alterung der Bevölkerung mit steigender Tendenz. Die Inzidenz der Arthrose steigt aber schon ab dem 40 Lebensjahr, wobei besonders posttraumatische und sekundäre Arthroseformen zum Tragen kommen.

Anspruch

Der Wunsch nach hoher Mobilität und Sport zieht sich als Phänomen ebenfalls durch alle Altersgruppe. Dies ist mit hohen Gelenkbelastungen verbunden und stellt damit eine große Herausforderung an vor allem früh degenerativ veränderte Gelenksstrukturen dar. In diesem Zusammenhang ist der orthopädisch tätige Arzt gefordert, die Belastbarkeit von geschädigten Gelenken abzuschätzen und so früh wie möglich präventive Schritte sowie gegebenenfalls konservative Therapien einzuleiten, um die Progression der Arthrose zu verhindern und damit den eventuell notwendigen Gelenkersatz möglichst weit nach hinten zu schieben.

Pain-guided activity modification during treatment for patellar tendinopathy: a feasibility and pilot randomized clinical trial

BACKGROUND

Activity modification is a key component of patellar tendinopathy treatment but there is a lack of evidence guiding activity modification prescription. Use of activity modification in treatment studies has varied widely and the impact of those recommendations has not been directly investigated or compared. The purpose of this study was to assess (1) the feasibility of using pain-guided activity modification during treatment for patellar tendinopathy and (2) if our outcome measures are responsive to changes in tendon health over the course of treatment.

METHODS

This was an unblinded, randomized two-arm pilot and feasibility study randomized clinical trial with parallel assignment, conducted in Newark, DE. Individuals between the ages of 16 and 40 years old with patellar tendinopathy were included. Participants were randomly assigned to a pain-guided activity (PGA) or pain-free activity (PFA) group using a spreadsheet-based randomization scheme. All participants received standardized treatment using a modified version of the heavy-slow resistance protocol 3×/week for 12 weeks. For the first 6 weeks, the PGA group used the Pain-Monitoring Model to guide activity outside of treatment and the PFA group was restricted from running, jumping, or activities that provoked their patellar tendon pain. Feasibility outcomes included recruitment, enrollment, randomization, compliance, and retention percentages. Clinical evaluations were conducted at baseline, 6, and 12 weeks to assess symptom severity, psychological factors, tendon morphology and mechanical properties, lower extremity function, and quadriceps muscle performance.

RESULTS

In a ~ 13-month period, 108 individuals were screened, 47/108 (43.5%) were eligible for participation, and 15/47 (32.0%) of those were enrolled (9 PGA, 6 PFA). The recruitment rate was 1.15 participants/month. The mean ± SD compliance with treatment was PGA: 86.1 ± 13.0% and PFA: 67.1 ± 30.7%. There was one missed evaluation session and two adverse events, which were not due to study interventions. Changes exceeding the smallest detectable change were observed for at least one outcome in each domain of tendon health.

CONCLUSIONS

Use of pain-guided activity modification during exercise therapy for patellar tendinopathy was found to be feasible, and the proposed outcome measures appropriate. Computer-based allocation concealment, blinding of evaluators, and greater recruitment of high-level athletes should be implemented in future trials.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03694730 . Registered 3rd of October, 2018.

Retrospective study of relationship between vastus medialis volume on SPECT-CT and outcome of unilateral total knee arthroplasty

Although the importance of quadriceps femoris function was reported previously, little is known about volume-related factors and their effects on clinical outcomes after total knee arthroplasty (TKA). We sought to determine whether there was a bilateral difference in vastus medialis muscle volume measured on single-photon emission computed tomography-computed tomography (SPECT-CT) in patients who underwent unilateral TKA. We also aimed to determine whether vastus medialis volume was related to osteoarthritis (OA) severity or scintigraphic uptake degree around the knee joint on SPECT-CT. And finally, we attempted to investigate the factors, such as vastus medialis volume and scintigraphic uptake degree, associated with the functional outcomes of TKA.This retrospective study included 50 patients (41 female, 9 male) undergone unilateral TKA due to primary OA. The maximal cross-sectional area of the vastus medialis was measured on axial SPECT-CT images. Scintigraphic uptake degrees and Kellgren-Lawrence (K-L) grade at the tibiofemoral joints were assessed. We compared maximal cross-sectional area of the vastus medialis on SPECT-CT for difference of bilateral lower limbs. We also analyzed the relationship between volume of vastus medialis and scintigraphic uptake measured on SPECT-CT and the severity of OA on conventional radiographs. The clinical outcomes were evaluated using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index at baseline and at 1 and 2 years after surgery. The relationship between preoperative muscle volume and scintigraphic uptake on SPECT-CT and WOMAC index was analyzed.The amount of muscle volume measured on SPECT-CT was smaller in operated limb in patients who underwent unilateral TKA. Preoperative vastus medialis muscle volume was not related to preoperative OA severity measured on conventional radiographs and scintigraphic uptake on SPECT-CT. However, a decreased vastus medialis muscle volume was related to worse clinical outcomes after TKA (P = .045), whereas the degree of scintigraphic uptake on SPECT-CT was not associated with postoperative clinical outcomes.Muscle volume of vastus medialis was decreased in the operated knee than in the nonoperated knee, and that was correlated with worse postoperative results. Even if the preoperative volume of vastus medialis were not related to OA severity on conventional radiographs and scintigraphic uptake on SPECT-CT, preservation and improvement of the muscle mass of the knee undergoing TKA is important.

Usefulness of Muscle Synergy Analysis in Individuals With Knee Osteoarthritis During Gait

OBJECTIVE

To clarify whether there are any muscle synergy changes in individuals with knee osteoarthritis, and to determine whether muscle synergy analysis could be applied to other musculoskeletal diseases.

METHODS

Subjects in this study included 11 young controls (YC), 10 elderly controls (EC), and 10 knee osteoarthritis patients (KOA). Gait was assessed on a split-belt treadmill at 3 km/h. A non-negative matrix factorization (NNMF) was applied to the electromyogram data matrix to extract muscle synergies. To assess the similarity of each module, we performed the NNMF analysis assuming four modules for all of the participants. Further, we calculated joint angles to compare the kinematic data between the module groups.

RESULTS

The number of muscle modules was significantly lower in the EC (2-3) and KOA (2-3) groups than in the YC group (3-4), which reflects the merging of late swing and early stance modules. The EC and KOA groups also showed greater knee flexion angles in the early stance phase. Contrarily, by focusing on the module structure, we found that the merging of early and late stance modules is characteristic in KOA.

CONCLUSION

The lower number of modules in the EC and KOA groups was due to the muscle co-contraction with increased knee flexion angle. Contrarily, the merging of early and late stance modules are modular structures specific to KOA and may be biomarkers for detecting KOA.

SIGNIFICANCE

Describing the changes in multiple muscle control associated with musculoskeletal degeneration can serve as a fundamental biomarker in joint disease.

Normalizing gastrocnemius muscle EMG signal: An optimal set of maximum voluntary isometric contraction tests for young adults considering reproducibility

BACKGROUND

Even though most studies normalize the surface EMG signal of the gastrocnemius muscle using a single position of maximum voluntary isometric contraction (MVIC), several studies tend to indicate that several positions are in fact needed to obtain a maximal voluntary activation (MVA) for most of the subjects. However, no combination of positions has already been described.

RESEARCH QUESTION

A combination of MVIC positions to normalize the EMG signal of the gastrocnemius muscle is investigated. the influence of using several positions on the reproducibility of the normalization process is evaluated.

METHODS

Twenty healthy volunteers (45 % female - 55 % male, 25.4 years (SD 4.3), 72.6 kg (SD 13.9), 1.78 m (SD 0.12)) were recruited. Six positions for MVIC were compared and the effect of several normalization combinations on a functional task (gait) was evaluated.

RESULTS

Several positions are needed to obtain at least 90 % of the MVA for 90 % of the volunteers even though the use of a single well-chosen position (unipodal standing position with knee fully extended and ankle fully plantar-flexed) will lead to no statistically significant differences of the gait evaluation during stance phase. For each position, five repetitions of the MVIC are recommended to obtain a valid MVA.

SIGNIFICANCE

This study confirms that using several MVIC positions is recommended when possible to normalize the gastrocnemius muscle EMG signal. However, in the situation of a patient where limited MVIC attempts are possible, using a single well-chosen position should not significantly influence the amplitude and the reproducibility of the measures.

Challenges with strengthening exercises for people with knee osteoarthritis and comorbid obesity: a qualitative study with patients and physiotherapists

OBJECTIVE

Explore challenges associated with implementing a home-based strengthening exercise program for people with knee osteoarthritis and comorbid obesity.

METHODS

Qualitative study embedded within a randomised controlled trial comparing two home-based strengthening programs (weight bearing functional exercise versus non-weight bearing quadriceps strengthening exercise) for people with knee osteoarthritis and comorbid obesity. Patients in both exercise programs attended five consultations with a physiotherapist and undertook a home-based exercise program for 12 weeks. Semi-structured individual telephone interviews were conducted with 22 patients after trial completion, and all seven physiotherapists who delivered trial interventions. Interviews were recorded, transcribed verbatim, and thematically analysed using an inductive approach.

RESULTS

Three themes arose: i) psychological challenges (false assumptions about exercise; fear of pain; disliking exercise; mental effort of weight bearing functional program; underestimating capability) ii) physical challenges (complexity of weight bearing functional program; cuff weights and straight leg raise problematic in non-weight bearing quadriceps program; other health conditions), and; iii) overcoming challenges (incentives to exercise; accountability; education and reassurance; tailoring the exercise program).

CONCLUSION

Patients and physiotherapists experienced numerous psychological and physical challenges to exercise, including a fear of pain, having false assumptions about exercise, difficulties with exercise performance, application of cuff weights, and adverse impacts of other health conditions.

A Randomized Controlled Pilot Study Comparing the Efficacy of Pulsed Radiofrequency Combined With Exercise Versus Exercise Alone in Pain Relief and Functional Improvement for Chronic Knee Osteoarthritis

OBJECTIVES

To compare the long-term efficacy between pulsed radiofrequency (PRF) combined with passive stretching (PRF-PS) exercise and PS exercise alone in reducing pain and improving quadriceps muscle strength and knee function.

METHODS

Sixty-two participants were randomly assigned with a 1:1 allocation to the PRF-PS exercise group or the PS exercise group. Level of pain, muscle strength, and knee function were assessed from baseline to the first, third, and sixth months after treatment using the VAS, peak torque (PT), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), respectively.

RESULTS

There were no significant differences at baseline between the 2 groups. Compared to exercise alone, participants achieved superior efficacy with PRF-PS in pain relief, improvement of muscle strength, and knee function. Moreover, the improvement of all variables was maintained for a longer period of time in the PRF-PS group. The reduction in participants' VAS pain intensity scores was superior for PRF-PS vs. PS with overall estimation (adjusted mean difference: -1.85 cm; 95% confidence interval [CI] -2.25, -1.45 cm; P = 0.000). The increase in participants' PT scores was superior for PRF-PS vs. PS with overall estimation (adjusted mean difference: 15.53 N. m; 95% CI 7.07, 23.98 N. m; P = 0.000; and 12.62 N. m; 95% CI 0.96, 24.28 N. m; P = 0.000 for PT 60 degrees/s and PT 180 degrees/s, respectively). The reduction in participants' WOMAC scores was superior for PRF-PS vs. PS with overall estimation (adjusted mean difference: -16.43; 95% CI -22.22, -10.64; P = 0.000).

DISCUSSION

The improvement in pain relief and knee function might be associated with restoration of muscle strength after PRF-PS exercise by overcoming muscle inhibition.

Utilizing the somatosensory system via vibratory stimulation to mitigate knee pain during walking: Randomized clinical trial

BACKGROUND

Pain and proprioception deficits are often associated with knee pathologies and resultant quadriceps muscle inhibition. There is a need for new approaches to mitigate active knee pain and restore muscle function during walking. Activating properties of the somatosensory system with common pain and sensory pathways offers a novel opportunity to enhance quadriceps function during walking.

RESEARCH QUESTION

Conduct a controlled clinical trial that investigates the effects of applying intermittent vibrational cutaneous stimulation during walking on knee pain and symptoms and their correlations to gait parameters.

METHODS

This longitudinal controlled cross-over clinical study included thirty-two patients randomly and blindly assigned to active Treatment A and passive Treatment B for 4 weeks with a 2-week washout period between treatments.

RESULTS

Subjects when wearing active Treatment A for 4 weeks had significant (p = 0.04) improvement in patient reported outcomes, while they had no significant differences with passive Treatment B (p > 0.7) compared to the no treatment condition. For Treatment A, subjects with low knee flexion moment and knee flexion angle in no-treatment condition exhibited the greatest increase in knee flexion moment/angle in the active treatment condition (R > 0.57, p < 0.001). These changes in gait measures were correlated significantly to changes in pain.

SIGNIFICANCE

This clinical trial indicates that knee pain can be reduced, and gait improved in a manner that enhances quadriceps function by applying intermittent cutaneous stimulation during gait in patients following knee injury or disease. The correlation between decreased pain and improved gait suggests that rehabilitation and exercise therapy may benefit from this treatment.

Sex- and osteoarthritis-related differences in muscle co-activation during weight-bearing tasks

BACKGROUND

Individuals with knee osteoarthritis (OA) demonstrate impairments in muscle function (i.e. muscle weakness, high muscle co-activation believed to have detrimental effects on joint integrity). Women with knee OA exhibit poorer health outcomes than men. Sex and muscle function are known risk factors for knee OA. It is unclear how these risk factors are associated with muscle function in knee OA and the implications for disease aetiology.

RESEARCH QUESTION

How does sex and knee osteoarthritis disease status relate to muscle function, specifically strength and muscle co-activation, during walking, stair negotiation and sit-to-walk activities.

METHODS

A cross-sectional study assessed muscle co-activation in 77 individuals with knee OA (mean[SD], 62.5[8.1] years; 48/29 women/men) and 18 age-matched controls (62.5[10.4] years; 9/9 women/men), during a series of walking, stair ascent and descent and sit-to-walk activities. Muscle strength of the knee extensors and flexors was assessed using maximal voluntary isometric contractions (MVIC). Electromyography was recorded from the vastus lateralis/medalis, rectus femoris, biceps femoris, semitendinosus, medial/lateral gastrocnemius normalised to MVIC. Multiple regression assessed the relationship between sex, disease status, and muscle strength on muscle co-activation.

RESULTS

Individuals with knee OA were weaker than controls, had higher hamstrings-quadriceps and medial-lateral co-activation for specific phases of gait. Women were weaker than men with higher muscle co-activation across all activities. Sex and muscle weakness, but not age or disease status predicted high muscle co-activation.

SIGNIFICANCE

High muscle co-activation was associated with female sex and muscle weakness regardless of disease status and age. High muscle co-activation is believed to be a compensatory mechanism for muscle weakness to maintain a certain level of function. High muscle co-activation is also thought to have detrimental effects on cartilage and joint integrity this may explain high muscle co-activation in women with muscle weakness and contribute to increased risk of incidence and progression of knee OA in women.

What are the effects of simulated muscle weakness on the sit-to-stand transfer?

Populations with lower extremity muscle weakness have difficulty performing the sit-to-stand (STS) transfer. The degree of weakness that can be tolerated before compromising the ability to perform this task is unknown. Using dynamic simulations, we investigated the effects of weakness before changes in kinematics/kinetics would be required. Lower extremity muscles were weakened globally and individually and muscle forces were re-estimated as the model tracked original task kinematics/kinetics. The STS transfer was sensitive to quadriceps and plantarflexor weakness, suggesting that strengthening these muscles or changing kinematics are essential for populations who have difficulty rising from a chair independently.

Girth, strength, and flexibility of the calf muscle in patients with knee osteoarthritis: A case-control study

Objectives

Reduced strength and girth in thigh muscles such as the quadriceps and the hamstrings have been observed in patients with knee osteoarthritis (OA). However, studies on the characteristics of calf muscles in these patients are lacking. This study aimed to evaluate the girth, strength, and flexibility of the calf muscle of patients with knee OA.

Methods

In this case–control study, we recruited 15 patients with knee OA and 15 healthy control participants. The girth, strength, and flexibility of the calf muscle were evaluated in one session using a flexible non-elastic tape measure (centimetre), a handheld dynamometer (Newton), and a standard goniometer (degree) to measure ankle dorsiflexion.

Results

Strength of the calf muscle strength was significantly lower in the patients with knee OA comapred with the control group (−42.03; 95% CI: −73.9, −10.1; p = .012). No significant differences in calf muscle girth (.27; 95% CI: −2.63, 3.16; p = .852) or flexibility (−1.93; 95% CI: −4.8, .93; p = .177) were found between the two groups.

Conclusion

In our study, patients with knee OA demonstrated reduced calf muscle strength. We recommend that the management of patients with knee OA include strengthening the calf muscles.

•

Patients with knee OA did not have reduced girth or flexibility in the calf muscle.

•

Patients with knee OA may demonstrate weakness in the calf muscle.

•

Calf muscle strength should be included in the management of patients with knee OA.

Influence of Antagonistic Hamstring Coactivation on Measurement of Quadriceps Strength in Older Adults

BACKGROUND

There is limited understanding of how antagonist muscle coactivation relates to measurement of strength in both individuals with and without knee osteoarthritis (KOA).

OBJECTIVE

This study sought to determine whether hamstring coactivation during a maximal quadriceps activation task attenuates net quadriceps strength.

DESIGN

Cross-sectional cohort analysis was conducted using data from the 60-month visit of the Multicenter Osteoarthritis Study (MOST).

SETTING

Laboratory.

PARTICIPANTS

A sample of 2328 community-dwelling MOST participants between the ages of 55 and 84 years, with or at elevated risk for KOA, completed the 60-month MOST follow-up visit. Of these, 1666 met inclusion criteria for the current study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE(S)

Quadriceps strength; percentage of combined hamstring coactivation (HC), medial HC, and lateral HC. Quadriceps and hamstring strength were assessed using an isokinetic dynamometer. Surface electromyography was used to assess muscle activation patterns. General linear models, adjusted for age, BMI, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Kellgren-Lawrence (KL) grade and study site, modeled the relationship between antagonist hamstring coactivation and quadriceps strength.

RESULTS

Men had significantly greater quadriceps strength (P < .001), history of knee injury (P < .001) and surgery (P = .002), and greater presence of varus malalignment (P < .001). Women had greater pain (P < .001) and proportion of KL grade ≥2 (P = .017). Gender-specific analyses revealed combined HC (P = .013) and lateral HC inversely associated with quadriceps strength in women (P = .023) but not in men (combined HC P = .320, lateral HC P = .755). A nonlinear association was detected between quadriceps strength and medial HC. Assessment of quartiles of medial HC revealed the third quartile had reduced quadriceps strength when compared to the lowest quartile of coactivation in both men and women.

CONCLUSIONS

Hamstring coactivation attenuates measured quadriceps strength in women with or at elevated risk for KOA.

LEVEL OF EVIDENCE

II.

Women with knee osteoarthritis increase knee muscle co-contraction to perform stand to sit

BACKGROUND

There is lack of sufficient research evidence when we examine how knee osteoarthritis (OA) affects performance of stand to sit, a very important task for daily function.

AIM

The aim of this study was to investigate if women with unilateral knee OA perform the stand to sit task in the same way as healthy adults of the same age.

METHODS

Fifteen women with knee OA (age 64.05 ± 4.23 years, height 161.52 ± 5.03 cm, and mass 75.23 ± 8.51 kg) and fifteen healthy subjects of the same age (age 62.13 ± 4.15 years, height 160.73 ± 5.10 cm, and mass 75.20 ± 9.87 kg) volunteered to participate. The experimental task required sitting to a chair starting from a bipedal standing position. Electromyographic activity of the vastus lateralis and biceps femoris was examined for both legs. In addition, joint kinematics of the lower limb and vertical ground reaction forces were recorded bilaterally.

RESULTS

Movement duration was not different between the groups. Women with knee OA showed significantly lower vastus lateralis activation and higher knee muscle co-contraction of the affected leg compared to the same leg of the control group. In addition, they had smaller knee range of motion for both legs compared to the control group participants.

CONCLUSION

Knee muscle co-contraction is employed by women with knee OA to perform the stand to sit movement at the same duration as their healthy counterparts. This compensatory mechanism may be important for the task execution, but at the same time, it can be harmful for the joint.

Differences in Baseline Joint Moments and Muscle Activation Patterns Associated With Knee Osteoarthritis Progression When Defined Using a Clinical Versus a Structural Outcome

Both structural and clinical changes can signify knee osteoarthritis progression; however, these changes are not always concurrent. A better understanding of mechanical factors associated with progression and whether they differ for structural versus clinical outcomes could lead to improved conservative management. This study examined baseline gait differences between progression and no progression groups defined at an average of 7-year follow-up using 2 different outcomes indicative of knee osteoarthritis progression: radiographic medial joint space narrowing and total knee arthroplasty. Of 49 individuals with knee osteoarthritis who underwent baseline gait analysis, 32 progressed and 17 did not progress using the radiographic outcome, while 13 progressed and 36 did not progress using the arthroplasty outcome. Key knee moment and electromyography waveform features were extracted using principal component analysis, and confidence intervals were used to examine between-group differences in these metrics. Those who progressed using the arthroplasty outcome had prolonged rectus femoris and lateral hamstrings muscle activation compared with the no arthroplasty group. Those with radiographic progression had greater mid-stance internal knee rotation moments compared with the no radiographic progression group. These results provide preliminary evidence for the role of prolonged muscle activation in total knee arthroplasty, while radiographic changes may be related to loading magnitude.

Muscle Co-Activation Across Activities of Daily Living in Individuals With Knee Osteoarthritis

OBJECTIVE

Muscle co-activation has been shown to be elevated in individuals with knee osteoarthritis (OA) during gait. Comparisons of muscle co-activation across different activities of daily living such as stair negotiation have yet to be explored. The aim of this study was to explore muscle co-activation across different activities of daily living in patients with knee OA.

METHODS

Muscle co-activation was assessed in 77 symptomatic knee OA patients (mean ± SD age 62.5 ± 8.1 years, body mass index 29.4 ± 6.0 kg/m² , and sex 48:29 female:male) using electromyography (EMG), during a series of walking, stair negotiation (ascent, descent), and sit-to-walk activities. EMG was recorded from 7 sites, mediolateral gastrocnemius, biceps femoris, semitendinosus, vastus lateralis/medialis, and rectus femoris, and normalized to maximal voluntary isometric contraction. Correlation was used to assess the consistency of co-activation across activities. Repeated-measures analysis of variance assessed the muscle combination by activity differences.

RESULTS

Muscle co-activation was highest during stair ascent. When comparing muscle combinations within the same activity, we found that correlations ranged from r = 0.003 to r = 0.897, of which 80% of the combinations were significant. Between activities, muscle co-activation was significantly different (P < 0.05). Mediolateral muscle co-activation was higher than hamstrings/quadriceps across activities.

CONCLUSION

Two muscle co-activation strategies were observed during activities of daily living in patients with knee OA to maintain stability. Muscle co-activation was higher during more challenging activities, particularly when the joint was accepting load. Mediolateral muscle co-activation was higher than hamstrings/quadriceps, so that mediolateral co-activation was thought to be a stabilization mechanism, while hamstrings/quadriceps co-activation responds to knee flexion moments, suggesting that different muscle combinations may have different roles in responding to joint demand.

Preoperative hand-grip strength can be a predictor of stair ascent and descent ability after total knee arthroplasty in female patients

BACKGROUND

Hand-grip strength was reported to be important predictor of functional limitation and disability related to low muscle strength in old people. The purpose of this study was to determine whether preoperative hand-grip strength predicts stair ascent and descent ability after total knee arthroplasty (TKA).

METHODS

A total of 83 female patients (mean age 75.6 ± 7.2 years) who underwent unilateral TKA were included in this study. We measured body mass index, range of motion of both knees, bilateral quadriceps strength and hand-grip strength before and one year after TKA. One year after TKA, we had the subjects ascend and descend some stairs and recorded the gait pattern (step-to-step or step-over-step) and pain in both knees using a numerical rating scale. We divided the subjects into two groups according to gait pattern. These factors were compared between groups. Receiver Operating Characteristics (ROC) analysis was performed to estimate the preoperative hand-grip strength cut off point for the stair gait pattern.

RESULTS

Pre- and postoperative mean hand-grip strengths were 20.1 ± 5.0 kg and 20.7 ± 5.4 kg, respectively, and there was a strong positive correlation between them (r = 0.82, P < 0.001). Quadriceps strength of both limbs significantly improved after TKA (P < 0.001). After TKA, all patients were able to perform both stair ascent and descent. The gait patterns of 27 patients were step-to-step, and 56 patients were step-over-step. Preoperative and postoperative quadriceps strength of both limbs and preoperative and postoperative hand-grip strength were significantly different between the groups. According to the ROC curve, the optimal cut off values of preoperative hand-grip strength for which female patients could ascend and descend the stairs by step-over-step after TKA was set at 19 kg.

CONCLUSION

Preoperative hand-grip strength can be used in preoperative screening for stair ascent and descent ability after TKA.

Utilization and outcomes of neuromuscular electric stimulation in patients with knee osteoarthritis: a retrospective analysis

Background

Knee osteoarthritis (OA) is a chronic debilitating condition that is estimated to affect approximately 12% of the current adult population in the United States, and is associated with severe pain and disability. Among these patients, quadriceps muscle atrophy and concomitant weakness are frequent findings that contribute significantly to the burden of this disease. One emerging method of quadriceps muscle strengthening and rehabilitation in knee OA patients is the use of neuromuscular electrical stimulation therapy (NMES). Among the currently available systems for NMES therapy are the mobile health (mHealth) platforms allowing clinicians to monitor patient compliance and utilization trends in addition to capturing certain clinical outcome points. The aim of this study was to analyze data collected by a commercially available mobile-app controlled NMES platform and to examine: (I) utilization trends, (II) range-of-motion (ROM) changes, (III) pain scores, and (IV) patient reported outcome scores in patients who used this device as part of management of their knee OA.

Methods

We retrospectively reviewed patients who received mobile-app controlled NMES therapy for knee OA who were enrolled in this multi-center study between April 2017 and July 2018 in a cloud-based provider online portal system. A total of 41 patients met all our inclusion and exclusion criteria and were included in our final analysis. For each patient, the total number of NMES sessions, the duration of NMES therapy, visual analogue pain scores, ROM, and the Knee injury Osteoarthritis Outcome Score (KOOS, JR) were collected and analyzed. Patient's utilization trends were reported through analyzing NMES sessions and therapy durations. Descriptive statistics were utilized to analyze all relevant values.

Results

Across all patients, NMES therapy was utilized for an average of 3.5 months (range, 2 weeks to 10 months). On average, 90 sessions (range, 6 to 487) of therapy were received by patients for an average of 1,819 minutes (range, 120 to 9,740 minutes). Overall, patients achieved a mean ROM of 99˚±4.3˚ at final follow-up. Pain scores reduced from a mean of 5 points prior to device use (range, 1 to 8 points) to 2.5 points after use (range, 0 to 6 points) (P<0.001). Evaluation of KOOS questionnaires available for 17 patients showed incremental improvement from 52.46 points when therapy was started, to 63 points at 6 months following NMES therapy. No complications or adverse events were reported from any of the participants.

Conclusions

Although NMES therapy has been reported on by multiple authors, including in knee OA, there are limited have been no studies that have reported on the compliance, feasibility, and patient outcomes of using a mobile-app controlled NMES therapy devices in the setting of knee OA. Furthermore, the incorporation of cloud-based provider online platform may offer an additional advantage by allowing clinicians to monitor the progress and compliance of their patients in real-time. Therefore, patients who are making sub-optimal progress may benefit from an early intervention to modify their therapy protocol to achieve the best outcome.

Randomised study of the effects of neuromuscular electrical stimulation and low-level laser therapy on muscle activation and pain in patients with knee osteoarthritis

Background

The combined effects of low-level laser therapy and neuromuscular electrical stimulation on knee osteoarthritis have yet to be analysed. This study aimed to determine the individual and combined effects of laser therapy and electrical stimulation on muscle activation and pain in older people with knee osteoarthritis.

Methods

A total of 45 women aged 60–75 years with knee osteoarthritis were randomised into three groups to receive stimulation, laser or stimulation plus laser therapy. All three groups underwent a 4-week control period (without intervention) followed by an 8-week intervention period. The effects of the interventions on muscle inhibition, electrical activity and pain were analysed.

Findings

There was a decrease in muscle inhibition (effect size ≥0.6) and a reduction in pain (effect size >1.2) in all three groups. All therapies generated an increase in electrical activity (effect size 0.1–0.5).

Conclusions

Laser alone or in combination with electrical stimulation promoted similar increases in muscle activation and pain relief.

Perceived Instability Is Associated With Strength and Pain, Not Frontal Knee Laxity, in Patients With Advanced Knee Osteoarthritis

BACKGROUND

Increased varus/valgus laxity and perceived knee instability are independently associated with poor outcomes in people with knee osteoarthritis. However, the relationship between laxity and perceived instability is unclear.

OBJECTIVE

To assess whether knee extensor strength, pain, and knee laxity are related to perceived knee instability in patients with advanced knee osteoarthritis.

METHODS

This was a secondary analysis of a prospective observational cohort study of 35 patients (24 female; mean ± SD age, 60 ± 8 years; body mass index, 33 ± 5 kg/m²) with knee osteoarthritis awaiting total knee arthroplasty (36 knees). Within 1 month before arthroplasty, we measured isometric knee extension strength and self-reported knee pain (using the Knee injury and Osteoarthritis Outcome Score pain subscale). Patients rated their perception of knee instability as moderate to severe (n = 20) or slight to none (n = 15 patients, n = 16 knees) using the Knee Outcome Survey. We measured intraoperative varus/valgus knee laxity.

RESULTS

Lower knee extension strength (P = .01) and greater pain (P<.01) were associated with the perception of moderate to severe knee instability. Laxity was not related to perceived knee instability (P = .63).

CONCLUSION

Knee extension strength and pain were associated with perceived instability in people with advanced osteoarthritis. Varus/valgus laxity was not related to perceived knee instability.

LEVEL OF EVIDENCE

Level 2, prognostic. J Orthop Sports Phys Ther 2019;49(7):513-517. doi:10.2519/jospt.2019.8619.

Age- and Occupation-Based Public Health Considerations Related to Osteoarthritis of the Knee Joint: A Cadaveric Study

OBJECTIVE

Osteoarthritis (OA) literature makes minimal suggestion regarding age of disease onset or preventative strategies to reduce risk for onset in various populations. In 2005, the Centers for Disease Control and Prevention estimated that 33.6% of Americans 65+ years old were affected by OA; this cadaveric analysis suggests this is largely underestimated. The objective of this assessment is to identify at-risk populations for OA in the knee joint and make recommendations to prevent or delay disease onset.

DESIGN

Morphometric analyses of the articular cartilage of the tibial plateau were performed on cadaver specimens using Image Pro software on 3 age populations and surface area measurements for articular cartilage degradation were compared with donors' reported ages, clinical histories, and occupations.

RESULTS

Data showed that by the seventh decade of life, when patients are in their 60s, articular cartilage degeneration on the tibial plateau had commenced in 100% of specimen. All "homemakers" displayed above-average medial tibial plateau degeneration (32.33% ± 24.85%) for their age group while simultaneously reporting pathologies in their clinical history that encourage a sedentary lifestyle.

CONCLUSIONS

This assessment identifies an occupational class with a propensity to develop disease and also identifies a more realistic time frame than previous advisory committees have produced regarding age of disease onset and initiation of preventative measures. It is recommended that strengthening of the hip abductors and the musculature supporting the knee commence early in adult life to avoid valgus collapse and shearing at the knee joint.

Obesity effects on muscular activity during lifting and lowering tasks

Obesity is an emerging health problem and its incidence has been increasing throughout the workforce. In industrial workstations, vertical handling tasks (VHT), including lifting and lowering, are very common and can cause a significant muscular overload for the involved workers. During these tasks, muscular activity may be considerably affected by workers' body conditions. This study aims to analyze and compare the muscular activity in subjects with different obesity levels, using surface electromyography (EMG), during predefined VHT. Six different VHT (combining 5, 10 and 15-kg loads with two task styles) were performed. EMG data normalization was based on the percentage of maximum contraction during each task (MCT%). The results show that obesity influences the MCT%, which in turn increases the muscular effort during VHT. The current investigation demonstrates that obesity is a relevant musculoskeletal risk factor regarding VHT. The engineering analysis and design implications of this work can thus be perceived.

Investigating the Test-Retest Reliability and Validity of Hand-Held Dynamometry for Measuring Knee Strength in Older Women with Knee Osteoarthritis

Purpose: Hand-held dynamometry (HHD) can be used to evaluate strength when gold-standard isokinetic dynamometry (IKD) is not feasible. HHD is useful for measuring lower limb strength in a healthy population; however, its reliability and validity in individuals with knee osteoarthritis (OA) has received little attention. In this research, we examined the test-retest reliability and validity of HHD in older women with knee OA. We also examined the associations between reliability and symptom and disease severity. Method: A total of 28 older women with knee OA completed knee extension and flexion exertions measured using HHD and IKD. Intra-class correlation coefficients (ICC2,3), standard error of measurement, and minimal detectable change were calculated. Correlation coefficients and regressions evaluated the relationships between inter-trial differences and symptom and disease severity. Results: High test-retest reliability was demonstrated for both exertions with each device (ICC2,3 = 0.83-0.96). Variance between trials was not correlated with OA symptoms. Criterion validity was good (ICC2,3 = 0.76), but extension yielded lower agreement than flexion. Regression analysis demonstrated that true strength can be predicted from HHD measurements. Conclusions: HHD is a reliable tool for capturing knee extension and flexion in individuals with OA. Because of lower agreement, HHD might be best suited for evaluating within-subject strength changes rather than true strength scores. However, gold-standard extension strength magnitudes may reasonably be predicted from regression equations (r 2 = 0.82).

Comparing functional dynamic normalization methods to maximal voluntary isometric contractions for lower limb EMG from walking, cycling and running

There is no consensus on the most appropriate method for normalizing an individual's electromyography (EMG) signals from walking, cycling and running in the same data collection. The aim of this study was to compare how the magnitude and repeatability of normalization values differ from three normalization methods and to compare their scaling effect in three moderate intensity activities. Three rounds of maximal voluntary isometric contractions (MVICs), sprint cycling and sprint running were performed to obtain normalization values for each method. EMG from five moderate intensity trials of walking, cycling and running were performed and normalized using each normalization value. Normalization values, coefficients of variation, and peak normalized EMG from the three moderate intensity activities were compared across normalization methods. Sprint running resulted in greater normalization values for 6/9 muscles. MVICs produced the lowest variance in 6/9 muscles. Comparing peak normalized signals of interest across normalization methods, there were significant differences in 6/9, 7/9 and 8/9 muscles for walking, cycling and running, respectively. When investigating a combination of walking, cycling and/or running EMG data, sprint running could be used for normalization, due to its simplicity and its ability to produce a larger normalization value, despite lower repeatability.

Co-activation is not altered in the contra-lateral limb of individuals with moderate knee osteoarthritis compared to healthy controls

BACKGROUND

Contra-lateral knee joint function in individuals with moderate knee osteoarthritis is not well understood, despite the functional burden of bilateral osteoarthritis on end stage clinical management. The purpose of this study was to determine whether co-activation and joint biomechanics are altered in the contra-lateral limb compared to age-matched controls.

METHODS

20 Individuals with moderate knee osteoarthritis and 20 asymptomatic individuals walked on an instrumented dual belt treadmill at a self-selected speed. Surface electromyography of the knee joint musculature, including quadriceps, hamstrings and gastrocnemius muscles, normalized to maximum voluntary isometric contractions, as well as sagittal plane motion and sagittal and frontal plane moments were collected. Co-contraction indices were calculated and discrete variables from motion and moment data were extracted. Two-sample t-tests and 2-sample mixed model ANOVAs were performed with alpha <0.05.

FINDINGS

Contra-lateral knee muscle co-activation differences were not found between groups (p > 0.65). Peak knee adduction moment (0.41 Nm/kg vs. 0.32 Nm/kg) and knee adduction moment impulse (0.14 Nm s/kg vs. 0.10 Nm s/kg) were higher in the contra-lateral limb compared to the asymptomatic group respectively, whereas the sagittal motion (9.8° vs. 14.4°) and moment ranges (0.66 Nm/kg vs. 0.86 Nm/kg) during stance were less dynamic (p < 0.03).

INTERPRETATION

The contra-lateral limb was functioning differently biomechanically despite no changes present in muscle co-activation. Findings suggest biomechanical changes are occurring without greater demand on the neuromuscular system to preserve contra-lateral joint function in moderate knee osteoarthritis gait. A greater focus should be made to address biomechanical abnormalities in both knees of individuals with moderate unilateral symptomatic knee osteoarthritis.