Relative impact of radiographic osteoarthritis and pain on quadriceps strength, proprioception, static postural sway and lower limb function

A causative role for periarticular skeletal muscle weakness in the progression of joint damage and pain in OA

Although osteoarthritis (OA) is regarded as a disease of the articular cartilage, recent research has demonstrated alterations in periarticular muscles that surround the affected joint. Here, we investigated changes in periarticular muscle during the progression of OA, as well as the cause-and-effect relationship between muscle weakness and OA, in a mouse model of OA by destabilization of the medial meniscus (DMM). Pathological phenotypes in the periarticular muscles were assessed in the early and late stages of OA by DMM. OA pathology and pain behavior in the mice after DMM induction were examined in response to periarticular muscle weakness induced by multiple rounds of barium chloride (BaCl2) injections. The examinations were also performed in myostatin knockout mice with strengthened muscle phenotypes by muscle hypertrophy. Morphological alterations in the tibialis anterior (TA) and quadriceps muscles in DMM mice included variations in muscle-fiber size, aberrant extracellular matrix (ECM) deposition, inflammatory cell infiltration, and decreased muscle mass. Periarticular muscle fibers isolated from DMM mice showed reductions in the number of satellite cells and myogenic capacity of primary myoblast, as well as proliferation. DMM + muscle injury mice also showed exacerbated joint degeneration compared to the DMM vehicles. Myostatin knockout mice were characterized by attenuated OA and the complete abrogation of pain behavior after DMM. Our results suggest an association between muscle weakness and OA progression and pain.

Effect of adding hip exercises to general rehabilitation treatment of knee osteoarthritis on patients' physical functions: a randomized clinical trial

BACKGROUND

Hip adductor and abductor strength were both reduced in KOA patients. But to date, most of the researches have only focused on quadriceps combined with hip abductor strengthening versus quadriceps strengthening.

OBJECTIVE

The aim of the study is to evaluate the effect of adding hip abductor and adductor strengthening to quadriceps strengthening on lower limb strength, knee pain and physical function in patients with medial compartmental knee osteoarthritis.

METHODS

In this study, 42 participants, were randomly divided into two groups: the general treatment group (GT group) and the added-hip-exercise group (AH group). All participants were given a general rehabilitation treatment. The AH group performed hip abductor and adductor strengthening in addition to the general rehabilitation treatment. Knee and hip muscle strength, Five Times Sit-to-Stand Test (FTSST), the Timed Up and Go Test (TUGT), Numerical Rating Scale (NRS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were assessed at baseline and 6 weeks. A two-sided 2-sample unpaired t test was performed to compare the difference in mean change scores between AH and GT groups.

RESULTS

Finally, 36 participants completed the study: both groups consist of 18 participants. In the per-protocol analysis, the AH group had a greater improvement in knee extension strength (mean changes, 7.84 versus 36.48; P < 0.001) and hip abduction strength (mean changes, 5.05 versus 26.62; P = 0.001) than the control group. Similarly, the AH group had a greater improvement in the FTSST time (mean changes, 0.40 s versus 3.57 s; P < 0.001) and the TUFT time (mean changes, 0.18 s versus 1.67 s; P = 0.002) than the GH group. No statistical difference was found in the change of WOMAC pain scores and NRS between the 2 groups.

CONCLUSIONS

Older adults with knee OA in the AH group had superior muscle strength, symptoms and daily activity performance at the 6th week than those in the GT group. And adding hip exercises could expedite improvement of pain at the 2th week, but not at the 6th week.

TRIAL REGISTRATION

Clinical trial registration numbers and date of registration: ChiCTR-IOR-16009124, Registered 30 August 2016.

Associations of Muscle Strength with Central Aspects of Pain: Data from the Knee Pain and Related Health in the Community (KPIC) Cohort

Knee pain is associated with lower muscle strength, and both contribute to disability. Peripheral and central neurological mechanisms contribute to OA pain. Understanding the relative contributions of pain mechanisms to muscle strength might help future treatments. The Knee Pain and related health In the Community (KPIC) cohort provided baseline and year 1 data from people with early knee pain (n = 219) for longitudinal analyses. A cross-sectional analysis was performed with baseline data from people with established knee pain (n = 103) and comparative data from people without knee pain (n = 98). Quadriceps and handgrip strength indicated local and general muscle weakness, respectively. The indices of peripheral nociceptive drive were knee radiographic and ultrasound scores. The indices associated with central pain mechanisms were Pressure Pain detection Threshold (PPT) distal to the knee, and a validated self-report Central Aspects of Pain Factor (CAPF). The associations were explored using correlation and multivariable regression. Weaker quadriceps strength was associated with both high CAPF and low PPT at baseline. Year 1 quadriceps weakness was predicted by higher baseline CAPF (β = -0.28 (95% CI: -0.55, -0.01), p = 0.040). Weaker baseline and year 1 handgrip strength was also associated with higher baseline CAPF. Weaker baseline quadriceps strength was associated with radiographic scores in bivariate but not adjusted analyses. Quadriceps strength was not significantly associated with total ultrasound scores. Central pain mechanisms might contribute to muscle weakness, both locally and remote from the knee.

Neuromuscular joint function in knee osteoarthritis: A systematic review and meta-analysis

BACKGROUND

Neuromuscular alterations are common in people with knee osteoarthritis (KOA). A comprehensive understanding of these alterations is important to enable targeted rehabilitation strategies.

OBJECTIVES

This systematic review and meta-analysis aimed to comprehensively understand the neuromuscular alterations around the knee joint in people with KOA.

METHODS

Moderate- and high-quality studies based on a modified version of the Downs and Black checklist, comparing neuromuscular function of peri‑articular muscles between people with KOA and controls were retrieved from five databases from inception to October 2020. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and torque-related outcomes. Data were pooled according to structural KOA severity with sensitivity analysis based on sex. Evidence levels are presented in evidence gap maps.

RESULTS

A total of 7 high-quality and 22 moderate-quality studies were retained (1146 people with KOA and 1353 age- and sex-matched controls). Studies demonstrated quadriceps and hamstring strength deficits and increased hamstring-to-quadriceps strength ratios across KOA severities. Women presented lower quadriceps strength at early KOA (very limited evidence) and lower voluntary activation at end stage KOA (very limited evidence) as compared with controls, whereas men did not (moderate evidence). People with KOA also demonstrated lower quadriceps force control ability with no change in rapid force production (very limited evidence). Voluntary activation deficits for quadriceps were evident (moderate evidence), with no change in quadriceps cortical excitability (very limited evidence) or soleus spinal reflexes (very limited evidence). No muscle size change was demonstrated except for the vastus medialis (limited evidence). Evidence gaps were found for neural and torque-related measures and differences in hamstring, gastrocnemius, soleus, and popliteus.

CONCLUSIONS

Neuromuscular deficits are evident across different structural KOA severities and are seen in muscle strength, voluntary activation, muscle size, and force control ability. Women may exhibit these alterations to a greater extent than men.

PROSPERO REGISTRATION NUMBER

CRD42019160845.

Asymmetries and relationships between muscle strength, proprioception, biomechanics, and postural stability in patients with unilateral knee osteoarthritis

Background: The pathological mechanism of knee osteoarthritis (KOA) is unknown. KOA degeneration may be associated with changes in muscle strength, proprioception, biomechanics, and postural stability.

Objective: This study aimed to assess asymmetries in muscle strength, proprioception, biomechanics, and postural stability of bilateral lower limbs in patients with unilateral KOA and healthy controls and analyze correlations between KOA and these parameters.

Methods: A total of 50 patients with unilateral KOA (age range: 50-70) and 50 healthy subjects were recruited as study participants (age range: 50-70). Muscle strength, proprioception, femorotibial angle (FTA), femoral condylar–tibial plateau angle (FCTP), average trajectory error (ATE), and center of pressure (COP) sways areas were accessed in study participants, and the correlation between these variables was investigated.

Results: In patients with unilateral KOA, lower limb muscle strength was significantly lower on the symptomatic side than on the asymptomatic side (p < 0.01), while the proprioception (degree error), FTA, FCTP, and ATE were substantially higher compared to the asymptomatic side (p < 0.01). However, no significant difference was observed in the healthy controls (p > 0.05). Patients with unilateral KOA had lower muscle strength than healthy controls (p < 0.05), but their proprioception (degree error: the difference between the target and reproduction angles), ATE, and COP sway areas were higher (p < 0.05). Muscle strength was found to be negatively correlated with ATE and COP sways areas (p < 0.05), whereas proprioception (degree error) was positively correlated with ATE and COP sways areas (p < 0.05) in all study participants. However, no correlation was found between FTA, FCTP, and ATE, COP sways areas in patients with unilateral KOA (p > 0.05).

Conclusion: In patients with unilateral KOA, muscle strength, proprioception, biomechanics, and postural stability of bilateral limbs are asymmetrical in unilateral KOA patients. Muscle strength, proprioception, and postural stability are significantly associated variables, and changes in these variables should be considered in KOA prevention and rehabilitation.

Static posturography as a novel measure of the effects of aging on postural control in dogs

Aging is associated with impairment in postural control in humans. While dogs are a powerful model for the study of aging, the associations between age and postural control in this species have not yet been elucidated. The aims of this work were to establish a reliable protocol to measure center of pressure excursions in standing dogs and to determine age-related changes in postural sway. Data were obtained from 40 healthy adult dogs (Group A) and 28 senior dogs (Group B) during seven trials (within one session of data collection) of quiet standing on a pressure sensitive walkway system. Velocity, acceleration, root mean square, 95% ellipse area, range and frequency revolve were recorded as measures of postural sway. In Group A, reliability was assessed with intraclass correlation, and the effect of morphometric variables was evaluated using linear regression. By means of stepwise linear regression we determined that root mean square overall and acceleration in the craniocaudal direction were the best variables able to discriminate between Group A and Group B. The relationship between these two center-of-pressure (COP) measures and the dogs’ fractional lifespan was examined in both groups and the role of pain and proprioceptive deficits was evaluated in Group B. All measures except for frequency revolve showed good to excellent reliability. Weight, height and length were correlated with most of the measures. Fractional lifespan impacted postural control in Group B but not Group A. Joint pain and its interaction with proprioceptive deficits influence postural sway especially in the acceleration in the craniocaudal direction, while fractional lifespan was most important in the overall COP displacement. In conclusion, our study found that pressure sensitive walkway systems are a reliable tool to evaluate postural sway in dogs; and that postural sway is affected by morphometric parameters and increases with age and joint pain.

Correlation of medial longitudinal arch morphology with body characteristics and locomotive function in community-dwelling older women: A cross-sectional study

PURPOSE

This cross-sectional study aimed to investigate the effects of foot arch deformities on physical characteristics, muscular strength, and motor function in older women depending on the presence or absence of pain.

METHODS

Overall, 145 community-dwelling women aged 65 to 90 years were included in this study. We measured the foot arch height ratio (AHR, dorsal height/truncated foot length) and classified participants with AHR values above, below, or within 1.5 standard deviations into the high-arched group (HAG), Low-Arched Group (LAG), or normal-arched group (NAG), respectively. We also compared body characteristics (age, height, weight, body mass index (BMI), and skeletal mass index), muscle strength (handgrip strength and intrinsic foot strength (IFS)), and locomotive function (two-step value and gait speed) among the three groups.

RESULTS

Locomotive examination and muscle strength showed significant differences among the three groups only in the presence of pain; in the two-step test, HAG, NAG, and LAG values were 0.98 cm/cm, 1.19 cm/cm, and 1.18 cm/cm, respectively. The IFS measured 19.2 N, 24.2 N, 31.0 N, respectively, in the HAG, NAG, and LAG.

CONCLUSION

This study suggests that decreased IFS affects the mobility function of high-arched feet in older women. Although there was no significant difference in the evaluation of pain, HAG showed the highest average value, which is considered to contribute to the decreased two-step value. It has been suggested that a high-arched foot in the presence of pain is associated with IFS weakness and may affect the decline of mobility function in older women.

The Efficacy of Backward Walking on Static Stability, Proprioception, Pain, and Physical Function of Patients with Knee Osteoarthritis: A Randomized Controlled Trial

Objective

Impaired static stability and proprioception have been observed in individuals with knee osteoarthritis (KOA), which serves as a major factor increasing risk of fall. This study aimed to investigate the effects of backward walking (BW) on static stability, proprioception, pain, and physical function in KOA patients.

Methods

Thirty-two subjects with knee osteoarthritis were randomly assigned to either an BW group (BG, n = 16) or a control group (CG, n = 16). The participants in the BG received combination treatment of a 4-week BW training and conventional treatments, while those in the CG was treated with conventional treatments alone. All the participants were tested for the assessment of static stability [center of pressure (COP) sway, including sway length (SL, mm) and sway area (SA, mm²)] and proprioception [average trajectory error (ATE, %) and completion time (CT, second)]. Additionally, pain and knee function scores were measured by the numerical rating scale (NRS) and the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index, respectively. The assessments were conducted before and after intervention.

Results

The COP sway (SA and SL), ATE, NRS, and WOMAC showed a significant decline at week 4 in the two groups in contrast to their baseline (P < 0.05). Moreover, after 4-week intervention, the SA [(610.50 ± 464.26) mm² vs. (538.69 ± 420.52) mm²], NRS [(1.56 ± 0.63) vs. (2.25 ± 0.86)], and WOMAC [(11.69 ± 2.50) vs. (16.19 ± 3.94)] showed a significantly greater decrease in the BG compared to the CG (P < 0.05, respectively). However, the proprioception (ATE and CT) was closely similar between both groups at week 4 (P > 0.05).

Conclusion

BW is an effective adjunct to conventional treatment in reducing pain, improving physical function and static stability for KOA patients. It should be taken into consideration when developing rehabilitation programs for people with KOA.

Prevalence of ultrasound-detected knee synovial abnormalities in a middle-aged and older general population-the Xiangya Osteoarthritis Study

Background

There is paucity of data on the prevalence of ultrasound-detected synovial abnormalities in the general population, and the relationship between synovial changes and knee pain remains unclear. We examined the prevalence of synovial abnormalities on ultrasound and the relationship of these features with knee pain and radiographic osteoarthritis (ROA) in a community sample.

Methods

Participants aged 50 years or over were from the Xiangya Osteoarthritis Study, a community-based cohort study. Participants were questioned about chronic knee pain and underwent (1) ultrasonography of both knees to determine presence of synovial hypertrophy (≥ 4 mm), effusion (≥ 4 mm), and Power Doppler signal [PDS; yes/no]; and (2) standard radiographs of both knees (tibiofemoral and patellofemoral views) to determine ROA.

Results

There were 3755 participants (mean age 64.4 years; women 57.4%). The prevalence of synovial hypertrophy, effusion, and PDS were 18.1% (men 20.2%; women 16.5%), 46.6% (men 49.9%; women 44.2%), and 4.9% (men 4.9%; women 5.0%), respectively, and increased with age (P for trend < 0.05). Synovial abnormalities were associated with knee pain, with adjusted odds ratios (aORs) of 2.39 (95% confidence interval [CI] 2.00–2.86) for synovial hypertrophy, 1.58 (95%CI 1.39–1.80) for effusion, and 4.36 (95%CI 3.09–6.17) for PDS. Similar associations with ROA were observed, the corresponding aORs being 4.03 (95%CI 3.38–4.82), 2.01 (95%CI 1.76–2.29), and 6.49 (95%CI 4.51–9.35), respectively. The associations between synovial hypertrophy and effusion with knee pain were more pronounced among knees with ROA than those without ROA, and the corresponding P for interaction were 0.004 and 0.067, respectively.

Conclusions

Knee synovial hypertrophy and effusion are more common and increase with age, affecting men more than women. All three ultrasound-detected synovial abnormalities associate both with knee pain and ROA, and knee synovial hypertrophy or effusion and ROA may interact to increase the risk of knee pain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02539-2.

Determination of Pain Phenotypes in Knee Osteoarthritis Using Latent Profile Analysis

OBJECTIVE

To identify clinical phenotypes of knee osteoarthritis (OA) using measures from the following domains: 1) multimorbidity; 2) psychological distress; 3) pain sensitivity; and 4) knee impairment or pathology.

DESIGN

Data were collected from 152 people with knee OA and from 31 pain-free individuals. In participants with knee OA, latent profile analysis (LPA) was applied to the following measures: normalized knee extensor strength, Functional Comorbidity Index (FCI), Pain Catastrophizing Scale (PCS), and local (knee) pressure pain threshold. Comparisons were performed between empirically derived phenotypes from the LPA and healthy older adults on these measures. Comparisons were also made between pheonotypes on pain intensity, functional measures, use of health care, and history of knee injury.

RESULTS

LPA resulted in a four-group solution. Compared with all other groups, group 1 (9% of the study population) had higher FCI scores. Group 2 (63%) had elevated pain sensitivity and quadriceps weakness relative to group 4 and healthy older adults. Group 3 (11%) had higher PCS scores than all other groups. Group 4 (17%) had greater leg strength, except relative to healthy older adults, and reduced pain sensitivity relative to all groups. Groups 1 and 3 demonstrated higher pain and worse function than other groups, and group 4 had higher rates of knee injury.

CONCLUSION

Four phenotypes of knee OA were identified using psychological factors, comorbidity status, pain sensitivity, and leg strength. Follow-up analyses supported the replicability of this phenotype structure, but future research is needed to determine its usefulness in knee OA care.

Comparison of proprioception between osteoarthritic and age-matched unaffected knees: a systematic review and meta-analysis

PURPOSE

Theoretically, proprioceptive acuity could decrease in patients with knee osteoarthritis. However, there have been conflicting results in terms of proprioceptive deficit in osteoarthritic knees. The purpose of this systematic review and meta-analysis was to compare knee proprioception between osteoarthritic and healthy control knees.

METHODS

Studies comparing proprioception in osteoarthritic and healthy knees of age-matched control group using thresholds to detect passive motion (TTDPM) or joint position sense (JPS) tests were identified. JPS was assessed by measuring the reproduction of passive positioning (RPP) or active positioning (RAP) of the knees.

RESULTS

Seventeen studies were finally included in this meta-analysis. The pooled results of the analyses of the TTDPM for both 30° and 45° knee flexion showed that the mean angle of error was 0.83° greater (95% confidence interval: 0.44 to 1.23°; p < 0.001) in the osteoarthritic knees than in control knees. The pooled data of the RAP and RPP also showed that the mean angle of error was 1.89° greater in the osteoarthritic knees than in the control group. The mean difference in the angle of error between the osteoarthritic knees and control group was 1.06° greater in the JPS test than in the TTDPM (p < 0.001).

CONCLUSION

The knee proprioceptive acuity of the patients with knee osteoarthritis was poorer than that of the patients with unaffected knees in the age-matched control group both in terms of the TTDPM and JPS; clinical relevance of these deficits needs to be clarified in further studies.

LEVEL OF EVIDENCE

Meta-analysis, Level II.

Proprioception After Multiligament Knee Injury: Does Ligament Repair Lead to Better Proprioceptive Acuity Than Ligament Reconstruction?

Introduction

Multiligament knee injuries are uncommon but serious injuries. There is ongoing debate on the optimal treatment of these injuries. We designed a study to establish the effects of repair or reconstruction on proprioceptive outcomes following multiligament injury to the knee.

Materials and Methods

A total of 34 patients were analysed by independent researchers who had no conflict of interest in the cases (23 in the repair group and 11 in the reconstruction group). Proprioception of the knee was measured using a previously validated tool to assess the reproduction of passive positioning. Functional outcome was measured using the Lysholm score. Sub-group analysis was performed. The mean time from injury to review was 83 months (range: 25-193 months).

Results

There were no significant differences in proprioceptive acuity between the injured (5.9±4.2°; range: 1.0-18.3°) and uninjured contralateral (control) knees (5.2±3.8°; range: 1.0-15.0°; p=0.35). Similarly, there was no significant difference in proprioceptive acuity identified between the injured knees that underwent repair (6.0±4.3°; range: 1.0-18.3°) or reconstruction (5.0±3.6°; range: 1.3-14°; p=0.53).

Overall knee outcomes were good; the mean Lysholm score at final follow-up was 75.5±16.8 (range: 36-100). No significant differences were identified in any of the sub-groups.

Conclusions

We were unable to identify any differences in knee proprioceptive acuity between injured knees and controls nor between the types of surgical treatment, demonstrating equivocal recovery for both methods of treatment.

Psychometric properties and domains of postural control tests for individuals with knee osteoarthritis: a systematic review

Individuals with knee osteoarthritis (OA) commonly demonstrate impaired postural control. We aimed to systematically review psychometric properties of tests that assess postural control in people with knee OA and secondly, to determine domains of postural control measured by these tests. PubMed, CINAHL, Embase and Web of Science databases were searched to January 2019. Two independent review authors screened references according to eligibility criteria. The Consensus-based Standards for the selection of health Measurement Instruments were used to evaluate study methodological quality. Postural control tests identified from included studies were assessed to determine postural control constructs using the Systems Framework for Postural Control identifying nine domains. Following the screening of 2643 references, five cross-sectional studies and one longitudinal study (n = 408) were included. Four studies evaluated reliability, validity or responsiveness of three clinical measures: Community Balance and Mobility Scale, Star Excursion Balance Test and Tinetti Performance Oriented Mobility Assessment. Two assessed reliability or validity of a force platform. Results showed that evidence for reliability, validity and responsiveness of all these postural measures is limited. The most common domain of postural control assessed was 'static stability'. No study used measures that evaluated all nine postural control domains. Our results highlight limited investigation of psychometric properties specific to postural control in knee OA. The few existing ones have limitations regarding psychometric robustness and completeness regarding different domains of postural control. Future research should focus on verifying the quality of existing tools to evaluate postural control in knee OA for research and clinical purposes.

What is the influence of severity levels of knee osteoarthritis on gait initiation?

BACKGROUND

The anticipatory postural adjustments required for gait initiation have not yet been investigated in older adults with different levels of severity of knee osteoarthritis. This study aimed to evaluate the anticipatory postural adjustments adopted by older adults with different severity levels of knee osteoarthritis during gait initiation.

METHODS

Sixty-seven older adults with knee osteoarthritis (mild, moderate, and severe levels) and 11 healthy older adults control were evaluated bilaterally with a force plate to analyze gait initiation. The center of pressure trajectory during gait initiation was divided into four phases: three anticipatory postural adjustments, and a locomotor phase. The length, duration, and velocity of each phase were calculated.

FINDINGS

The results showed that during the right and left limbs swing forward, the severe and moderate knee osteoarthritis groups presented a significant reduction in the length of anticipatory postural adjustment phases, locomotion, duration, and velocity (P < 0.05). The severe knee osteoarthritis group presented a significantly higher body mass index (P < 0.003) than the other groups. However, just the healthy group presented a correlation between body mass index and anticipatory postural adjustments.

INTERPRETATION

Our results demonstrated that older adults with severe and moderate levels of knee osteoarthritis adopt longer lasting and slower anticipatory postural adjustment phases, lower locomotion, and lower center of pressure displacement during gait initiation, suggesting that this population has adaptive strategy in performing gait initiation, which is significantly changed by the knee osteoarthritis severity level.

Lower extremity proprioceptive sensation in patients with early stage knee osteoarthritis: A comparative study

BACKGROUND

Knee OA causes pain and proprioceptive impairment. The body acts as a closed kinetic chain, and deformation on the knee cannot only affect the knee joint but also can affect the other joints.

OBJECTIVE

To assess the proprioception of lower extremity in early stage knee osteoarthritis compared with without knee osteoarthritis individuals.

METHODS

The study sample consisted of 26 adults with early stage knee osteoarthritis and 26 subjects without knee osteoarthritis individuals. Western Ontario and McMaster Universities Osteoarthritis Index was used for clinical disease severity. Visual Analogue Scale was used for pain severity. Proprioception (position and motion sense) was measured by isokinetic dynamometer.

RESULTS

Western Ontario and McMaster Universities Osteoarthritis Index total score was 10.9 ± 5. Visual Analogue Scale scores during activity were found to be significantly higher than the scores at rest and night for both sides. Hip flexion and internal rotation joint position sense were significantly different between two groups (all p's < 0.05). Hip abduction, knee flexion, ankle and subtalar position sense, as well as hip and knee motion sense were similar between groups (all p's > 0.05). Ankle dorsiflexion and eversion motion sense were significantly different between two groups (all p's < 0.05).

CONCLUSIONS

This study demonstrated that the hip flexion and internal rotation position sense and ankle/subtalar joints motion sense may be affected on early stage of knee osteoarthritis. Investigation of the mechanism of proprioception for joints and also focusing on the longitudinal relationship between proprioception, knee OA disease and symptoms is recommended for future studies.

Association between thigh muscle strength four years after partial meniscectomy and radiographic features of osteoarthritis 11 years later

Background

Meniscus injury and meniscectomy both entail increased risk of knee osteoarthritis (OA). Thigh muscle weakness is a suggested mediator of OA but there is little evidence of its importance for knee OA development after meniscectomy. This study aimed to examine the association between thigh muscle strength after partial meniscectomy in middle-aged subjects with a non-traumatic meniscal tear and later radiographic knee OA changes.

Methods

Thirty-four out of 45 participants in an exercise-trial underwent testing for isokinetic thigh muscle strength 4 years after arthroscopic partial meniscectomy and had radiographic examination 11 years later (15 years post-surgery, mean age at follow-up of 57 years (range 50–61)). Outcomes were grade of joint space narrowing and osteophyte score in the medial tibiofemoral compartment of the operated knee and the contralateral knee. We tested the association between muscle strength at baseline and the radiographic outcomes at follow-up using logistic regression analyses adjusted for sex and overweight.

Results

At follow-up, 33/34 subjects had joint space narrowing and 27/34 subjects had osteophytes in the operated knee, in the contralateral knee joint space narrowing was found in 23 subjects. In the operated knee baseline knee extensor and flexor strength were negatively associated with grade of joint space narrowing at follow-up (OR 0.972 and 0.956, p = 0.028 and 0.026, respectively) and also with osteophyte score (OR 0.968 and 0.931, p = 0.017 and 0.011, respectively). In the contralateral knee longitudinal associations between strength and radiographic OA features were similar, OR 0.949–0.972, p < 0.05.

Conclusion

The finding that stronger thigh muscles 4 years after meniscectomy were associated with less severe osteoarthritic changes in the medial tibiofemoral compartment of both the operated and contralateral knee 11 years later, may suggest that strong thigh muscles can help to preserve joint integrity in middle-aged subjects at risk of knee OA.

The effects of pain on quadriceps strength, joint proprioception and dynamic balance among women aged 65 to 75 years with knee osteoarthritis

Background

Patients with knee osteoarthritis (OA) were reported to have quadriceps weakness, and impaired proprioception, both related to pain and swelling. It is unclear whether pain alone a causal factor to above findings over the knee joint. The purpose of this study was to assess the effects of knee pain alone on the quadriceps strength, proprioception and dynamic balance in subjects with bilateral knee OA without joint swelling.

Methods

Fourty females with mean age of 68.3 years were involved in this cross-sectional study. The inclusion criteria were bilateral knee OA without joint swelling, with a visual analogue pain scale difference (> 1) between each knee. Patients all underwent assessment of the isokinetic strength of knee muscles, knee proprioceptive acuity, and dynamic balance.

Results

Patients’ more painful knee had weaker isokinetic quadriceps strength than less painful knee at both 60 °/s and 180 °/s (p = 0.01, p = 0.01, respectively). There were no differences in proprioceptive acuity between both knees in all three knee positions. Meanwhile, there was a significant difference in the dynamic balance index measurement between both knees (more painful versus less painful: 3.88 ± 1.15 vs. 3.30 ± 1.00, p = 0.01). Quadriceps strength was associated with dynamic balance stability (60 °/s, r = − 0.578, p <  0.01; 180 °/s, r = − 0.439, p <  0.01).

Conclusions

For patients with knee OA, the more painful knee was associated with weaker quadriceps and poor balance ability. To improve lower limb function and balance stability of the older persons having knee OA, physicians should take the optimal pain management strategy.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0932-y) contains supplementary material, which is available to authorized users.

Association of malalignment, muscular dysfunction, proprioception, laxity and abnormal joint loading with tibiofemoral knee osteoarthritis - a systematic review and meta-analysis

Background

To investigate (1) the association of specific biomechanical factors with knee osteoarthritis and knee osteoarthritis development, and (2) the impact of other relevant risk factors on this association.

Methods

MEDLINE, EMBASE, CINAHL and SPORTDiscus were searched up until April 2017. Studies were included if they fulfilled the following criteria: the study 1) assessed the association of a biomechanical factor with knee osteoarthritis, or knee osteoarthritis development; 2) reported on skeletal malalignment, muscular dysfunction, impaired proprioception, laxity and abnormal loading during gait; 3) was a cohort study with participants developing knee osteoarthritis and participants not developing knee osteoarthritis, or a case-control or cross-sectional study with participants with knee osteoarthritis and without knee osteoarthritis. Risk of bias was assessed with the QUIPS tool and meta-analyses were performed using random effects models.

Results

Of 6413 unique studies identified, 59 cross-sectional studies were eligible for meta-analyses (9825 participants, 5328 with knee osteoarthritis). No cohort studies fulfilled the inclusion criteria. Compared with healthy controls, patients with knee osteoarthritis have higher odds of having lower muscle strength, proprioception deficits, more medial varus-valgus laxity and less lateral varus-valgus laxity. Patients with medial knee osteoarthritis have higher odds of having a higher knee adduction moment than healthy controls. Level of evidence was graded as ‘very low’ to ‘moderate’ quality. Due to large between study differences moderation of other risk factors on biomechanical risk factors could not be evaluated.

Conclusions

Patients with knee osteoarthritis are more likely to display a number of biomechanical characteristics. The causal relationship between specific biomechanical factors and the development of knee osteoarthritis could not be determined as no longitudinal studies were included. There is an urgent need for high quality, longitudinal studies to evaluate the impact of specific biomechanical factors on the development of knee osteoarthritis.

Trial Registration

(PROSPERO ID: CRD42015025092).

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2202-8) contains supplementary material, which is available to authorized users.

Examining the diagnostic accuracy of static postural stability measures in differentiating among knee osteoarthritis patients with mild and moderate to severe radiographic signs

BACKGROUND

Clinicians need a reliable and accurate tools that can best identify and classify balance impairments between mild and moderate to severe grades of knee osteoarthritis (OA).

RESEARCH QUESTION

This study was designed to investigate the accuracy of postural measurements to discriminate between these two groups of knee OA.

METHODS

A total of 130 patients with knee OA based on the Kellgren-Lawrence (KL) grading scale were categorized into 65 patients with mild (a KL grade≤ 2) and 65 patient with moderate to severe (a KL grade≥3) radiographic sign. Static postural control was assessed on the force plate in three conditions of double leg stance with open (DO) and closed eyes (DC) and single leg stance with open eyes (SO). The accuracy for static postural control parameters was determined by calculation of sensitivity, specificity, area under the Receiver Operating Characteristic (ROC) curve (AUC) and likelihood ratios (LRs).

RESULTS

Our results showed that standard deviation (SD) of velocity in anterior-posterior (AP) direction had the highest sensitivity and specificity in conditions of DO and DC, respectively. ROC curve analysis indicated that measures of mean and SD velocity in medio-lateral (ML) direction in conditions of DO and DC had acceptable levels of accuracy (AUC > 0.70) in discriminating between the two groups of knee OA patients. Also, based on LR results, SD of velocity in AP direction had the best ability for ruling in and ruling out moderate to severe grade of knee OA patients in conditions of DC and DO, respectively.

SIGNIFICANCE

Our findings provide evidence for selection of mean velocity and SD of velocity in identifying and discriminating static postural performance in patients with mild and moderate to severe grades of knee OA.

What is the evidence for a role for diet and nutrition in osteoarthritis?

As current treatment options in OA are very limited, OA patients would benefit greatly from some ability to self-manage their condition. Since diet may potentially affect OA, we reviewed the literature on the relationship between nutrition and OA risk or progression, aiming to provide guidance for clinicians. For overweight/obese patients, weight reduction, ideally incorporating exercise, is paramount. The association between metabolic syndrome, type-2 diabetes and OA risk or progression may partly explain the apparent benefit of dietary-lipid modification resulting from increased consumption of long-chain omega-3 fatty-acids from oily fish/fish oil supplements. A strong association between OA and raised serum cholesterol together with clinical effects in statin users suggests a potential benefit of reduction of cholesterol by dietary means. Patients should ensure that they meet the recommended intakes for micronutrients such as vitamin K, which has a role in bone/cartilage mineralization. Evidence for a role of vitamin D supplementation in OA is unconvincing.

Effect of a low-intensity, self-management lifestyle intervention on knee pain in community-based young to middle-aged rural women: a cluster randomised controlled trial

Background

Knee pain is common with obesity and weight gain being important risk factors. Previous clinical trials have focused on overweight or obese adults with knee pain and osteoarthritis and demonstrated modest effects of intense weight loss programs on reducing knee pain despite very significant weight loss. There has been no lifestyle intervention that targets community-based adults to test its effect on prevention of knee pain. We aimed to determine the effect of a simple low-intensity self-management lifestyle intervention (HeLP-her), proven in randomised controlled trials to improve lifestyle and prevent weight gain, on knee pain in community-based young to middle-aged rural women.

Methods

A 1-year pragmatic, cluster randomised controlled trial was conducted in 649 community-based women (aged 18–50 years) to receive either the HeLP-her program (consisting of one group session, monthly SMS text messages, one phone coaching session, and a program manual) or one general women’s health education session. Secondary analyses were performed in 390 women who had knee pain measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and 12-month follow-up. “Any knee pain” was defined as a WOMAC pain score ≥ 1. Knee pain worsening was defined as an increase in WOMAC pain score over 12 months.

Results

Thirty-five percent of women had “any knee pain” at baseline. The risk of knee pain worsening did not differ between the intervention and control groups over 12 months. For women with any knee pain at baseline, those in the intervention arm had a lower risk of knee pain worsening compared with those in the control arm (OR 0.37, 95% CI 0.14–1.01, p = 0.05), with a stronger effect observed in women with body mass index ≥ 25 kg/m² (OR 0.28, 95% CI 0.09–0.87, p = 0.03).

Conclusions

In community-based young to middle-aged women, a simple low-intensity lifestyle program reduced the risk of knee pain worsening in those with any knee pain at baseline, particularly in those overweight or obese. Pragmatic lifestyle programs such as HeLP-her may represent a feasible lifestyle intervention to reduce the burden of knee pain in the community.

Trial registration

ACTRN12612000115831, registered 24 January 2012.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1572-5) contains supplementary material, which is available to authorized users.

Effects of aquatic exercise and land-based exercise on postural sway in elderly with knee osteoarthritis

Background: Knee Osteoarthritis (knee OA) is the most common joint disease in the elderly. It is a major cause of walking disability and balance impairment. The balance impairment or increase postural sway may result in increased risk of fall. Objectives: Compare effects of aquatic exercise and land-based exercise on postural sway and physical performance (pain, quality of life, leg muscle strength and leg muscle flexibility) in the elderly with knee OA. Subjects and methods: Fifty elderly women with knee OA were recruited for this study. They were randomized into aquatic exercise (n=25) and land-based exercise group (n=25). Postural sway views by anterior-posterior amplitude, medio-lateral amplitude, and total area were measured in subjects with eye opened or closed during double and single leg stance after six-week training, using the Force platform. Functional outcome was tested by the modified WOMAC. Knee injury and Osteoarthritis Outcome Score (KOOS), and pain scale were tested by Visual Analog Scale (VAS). Leg muscle strength was measured by chair stand, and leg muscle flexibility was measured by sit-andreach test. Aquatic group exercised at King Chulalongkorn Memorial Hospital therapeutic pool, while landbased group exercised at home. Results: In comparing postural sway before and after exercise, reduction in postural sway and pain, and increase in strength, the aquatic group were significantly better than those for land-based group (p <0.05). WOMAC, KOOS scores, and sit-and-reach test after six-weeks training were improved after exercise, but these were not significantly different between groups (p >0.05). Conclusion: Elderly patients with knee OA need exercise to improve balance and reduce sway. Six-week aquatic exercise was better than land-based exercise in sway reduction.

Decreased muscle mass is independently associated with knee pain in female patients with radiographically mild osteoarthritis: a nationwide cross-sectional study (KNHANES 2010-2011)

To evaluate the association between muscle mass and knee pain in relation to radiographic severity of knee osteoarthritis. We consulted nationwide health examination and survey records collected from 2010 to 2011 and extracted data regarding female patients aged > 50 years and diagnosed with knee osteoarthritis. Radiographic severity was assessed on plain radiographs using the Kellgren-Lawrence system, whereas appendicular skeletal mass was obtained from dual-energy X-ray absorptiometry data. We performed multivariate logistic regression to evaluate the association between knee pain and muscle mass index (appendicular skeletal muscle mass divided by body weight in percentile) in patient groups stratified by radiographic severity of knee osteoarthritis. Among 17,476 participants of the national survey, 2013 female knee osteoarthritis patients were identified and stratified by radiographic severity (grade ≤ 1, n = 1136; grade 2, n = 240; grade 3, n = 379; and grade 4, n = 258). For mild osteoarthritis (Kellgren-Lawrence grade 2), muscle mass index was significantly lower in patients with knee pain than in those without knee pain (24.9 ± 3.9 vs 26.5 ± 6.3%, P = 0.023), whereas no such difference was noted for severe osteoarthritis (Kellgren-Lawrence grade > 2). After adjusting for clinical variables by multivariate logistic regression, decreased muscle mass index remained significantly associated with knee pain in patients with mild osteoarthritis but not in those with severe osteoarthritis (regression coefficient 0.915, 95% confidence interval 0.854-0.981, P = 0.012). Lower muscle mass may be a risk factor for knee pain in patients with radiographically mild knee osteoarthritis but not in those with radiographically severe osteoarthritis.

Comparative effects of proprioceptive and isometric exercises on pain intensity and difficulty in patients with knee osteoarthritis: A randomised control study

PURPOSE

The study compared the effects of isometric quadriceps exercise and proprioceptive exercise on pain, joint stiffness and physical difficulties of patients with knee osteoarthritis.

SUBJECTS

Forty-five patients with history of knee osteoarthritis were randomly allocated into two groups; A with 23 subjects and B with 22 subjects.

METHODS

All subjects received infrared radiation for 20 minutes and kneading massage with methyl salicylate ointment. Group A underwent proprioceptive exercises while Group B had isometric quadriceps exercise. Each exercise session lasted for 10 minutes according to standard protocol, twice in a week for six weeks. Pre-treatment, 3rd week and 6th week pain intensity, joint stiffness and physical difficulties were assessed using Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. Statistical package for social sciences (SPSS) version 17 was used to analyse the data while descriptive and inferential statistics were used to summarise the result.

RESULTS

Proprioceptive exercises reduced pain intensity significantly (F = 4.76; p = 0.00) at 6th week with effect size of 2.79, and physical difficulty (F = 3.69; p < 0.04) with effect size of 7.53 better than isometric exercises. There was a significant reduction in the pain intensity (F = 12.08; p < 0.001), and physical difficulties (F = 3.69, p = 0.04) in pre-treatment, 3rd week and 6th week in both Group A and B.

CONCLUSION

Both exercises are effective but proprioceptive exercises may be more effective in the management of patients with knee osteoarthritis (KOA) than isometric exercises.

Effects of aquatic exercise on muscle strength and functional performance of individuals with osteoarthritis: a systematic review

Water-based exercises are recommended for people with osteoarthritis (OA), due to the beneficial effects on physical function, quality of life and symptom reduction. However, the effects on muscle strength are still controversial. The aim of this review was to assess and compare the effects of aquatic exercise programs on muscle strength and physical function in people with OA. A systematic search was performed at Pubmed, Scopus and Web of Science databases. Clinical trials with interventions involving aquatic exercises for individuals with OA were included. The methodological quality of the studies was evaluated using the PEDro scale. 296 studies were found and twelve were selected: six studies comparing water-based exercises with land-based exercise, and six comparing water-based exercise groups with the control group. Exercise programs included muscle strengthening, aerobic, balance, flexibility and stretching exercises. Duration of the program, weekly frequency, intensity and progression varied between studies. Beneficial effects of aquatic exercise were found on physical function. However, only two of five studies that assessed muscle strength observed positive effect of aquatic exercise. Although it is difficult to compare studies and establish guidelines for the standardized protocol formulation, it was observed that water-based exercises can be effective on improving physical function and increasing muscle strength, since they are well-structured, with exercise intensity and overload controlled.

Comparative Effectiveness of Tai Chi Versus Physical Therapy for Knee Osteoarthritis: A Randomized Trial

BACKGROUND

Few remedies effectively treat long-term pain and disability from knee osteoarthritis. Studies suggest that Tai Chi alleviates symptoms, but no trials have directly compared Tai Chi with standard therapies for osteoarthritis.

OBJECTIVE

To compare Tai Chi with standard physical therapy for patients with knee osteoarthritis.

DESIGN

Randomized, 52-week, single-blind comparative effectiveness trial. (ClinicalTrials.gov: NCT01258985).

SETTING

An urban tertiary care academic hospital.

PATIENTS

204 participants with symptomatic knee osteoarthritis (mean age, 60 years; 70% women; 53% white).

INTERVENTION

Tai Chi (2 times per week for 12 weeks) or standard physical therapy (2 times per week for 6 weeks, followed by 6 weeks of monitored home exercise).

MEASUREMENTS

The primary outcome was Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at 12 weeks. Secondary outcomes included physical function, depression, medication use, and quality of life.

RESULTS

At 12 weeks, the WOMAC score was substantially reduced in both groups (Tai Chi, 167 points [95% CI, 145 to 190 points]; physical therapy, 143 points [CI, 119 to 167 points]). The between-group difference was not significant (24 points [CI, -10 to 58 points]). Both groups also showed similar clinically significant improvement in most secondary outcomes, and the benefits were maintained up to 52 weeks. Of note, the Tai Chi group had significantly greater improvements in depression and the physical component of quality of life. The benefit of Tai Chi was consistent across instructors. No serious adverse events occurred.

LIMITATION

Patients were aware of their treatment group assignment, and the generalizability of the findings to other settings remains undetermined.

CONCLUSION

Tai Chi produced beneficial effects similar to those of a standard course of physical therapy in the treatment of knee osteoarthritis.

PRIMARY FUNDING SOURCE

National Center for Complementary and Integrative Health of the National Institutes of Health.

Determination of Pain Phenotypes in Knee Osteoarthritis: A Latent Class Analysis Using Data From the Osteoarthritis Initiative

OBJECTIVE

Knee osteoarthritis (OA) is a broadly applied diagnosis that may describe multiple subtypes of pain. The purpose of this study was to identify phenotypes of knee OA, using measures from the following pain-related domains: 1) knee OA pathology, 2) psychological distress, and 3) altered pain neurophysiology.

METHODS

Data were selected from a total of 3,494 participants at visit 6 of the Osteoarthritis Initiative study. Latent class analysis was applied to the following variables: radiographic OA severity, quadriceps strength, body mass index, the Charlson Comorbidity Index (CCI), the Center for Epidemiologic Studies Depression Scale, the Coping Strategies Questionnaire-Catastrophizing subscale, number of bodily pain sites, and knee joint tenderness at 4 sites. The resulting classes were compared on the following demographic and clinical factors: age, sex, pain severity, disability, walking speed, and use of arthritis-related health care.

RESULTS

A 4-class model was identified. Class 1 (4% of the study population) had higher CCI scores. Class 2 (24%) had higher knee joint sensitivity. Class 3 (10%) had greater psychological distress. Class 4 (62%) had lesser radiographic OA, little psychological involvement, greater strength, and less pain sensitivity. Additionally, class 1 was the oldest, on average. Class 4 was the youngest, had the lowest disability, and least pain. Class 3 had the worst disability and most pain.

CONCLUSION

Four distinct pain phenotypes of knee OA were identified. Psychological factors, comorbidity status, and joint sensitivity appear to be important in defining phenotypes of knee OA-related pain.

Muscle Power Is an Independent Determinant of Pain and Quality of Life in Knee Osteoarthritis

OBJECTIVE

This study examined the relationships between leg muscle strength, power, and perceived disease severity in subjects with knee osteoarthritis (OA) in order to determine whether dynamic leg extensor muscle power would be associated with pain and quality of life in knee OA.

METHODS

Baseline data on 190 subjects with knee OA (mean ± SD age 60.2 ± 10.4 years, body mass index 32.7 ± 7.2 kg/m(2) ) were obtained from a randomized controlled trial. Knee pain was measured using the Western Ontario and McMaster Universities Osteoarthritis Index, and health-related quality of life was assessed using the Short Form 36 (SF-36). One-repetition maximum (1RM) strength was assessed using the bilateral leg press, and peak muscle power was measured during 5 maximum voluntary velocity repetitions at 40% and 70% of 1RM.

RESULTS

In univariate analysis, greater muscle power was significantly associated with pain (r = -0.17, P < 0.02) and also significantly and positively associated with SF-36 physical component summary (PCS) scores (r = 0.16, P < 0.05). After adjustment for multiple covariates, muscle power was a significant independent predictor of pain (P ≤ 0.05) and PCS scores (P ≤ 0.04). However, muscle strength was not an independent determinant of pain or quality of life (P ≥ 0.06).

CONCLUSION

Muscle power is an independent determinant of pain and quality of life in knee OA. Compared to strength, muscle power may be a more clinically important measure of muscle function within this population. New trials to systematically examine the impact of muscle power training interventions on disease severity in knee OA are particularly warranted.

Corticospinal and intracortical excitability of the quadriceps in patients with knee osteoarthritis

Deficits in voluntary activation of the quadriceps muscle are characteristic of knee osteoarthritis (OA), contributing to the quadriceps weakness that is also a hallmark of the disease. The mechanisms underlying this central activation deficit (CAD) are unknown, although cortical mechanisms may be involved. Here, we utilize transcranial magnetic stimulation (TMS) to assess corticospinal and intracortical excitability in patients with knee OA and in a comparably aged group of healthy older adults, to quantify group differences, and to examine associations between TMS measures and pain, quadriceps strength, and CAD. Seventeen patients with knee OA and 20 healthy controls completed testing. Motor evoked potentials were measured at the quadriceps by superficial electromyographic recordings. Corticospinal excitability was assessed by measuring resting motor threshold (RMT) to TMS stimulation of the quadriceps representation at primary motor cortex, and intracortical excitability was assessed via paired-pulse paradigms for short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). No statistically significant differences between patients with knee OA and healthy controls were found for RMT, SICI or ICF measures (p > 0.05). For patients with knee OA, there were significant associations observed between pain and RMT, as well as between pain and ICF. No associations were observed between CAD and measures of corticospinal or intracortical excitability. These data suggest against direct involvement of corticospinal or intracortical pathways within primary motor cortex in the mechanisms of CAD. However, pain is implicated in the neural mechanisms of quadriceps motor control in patients with knee OA.

Validity and reliability of the community balance and mobility scale in individuals with knee osteoarthritis

BACKGROUND

There is a high incidence of falls in older adults with knee osteoarthritis (OA). Adequate dynamic balance and mobility reduce the risk of falls; however, there are currently no validated, advanced tests of dynamic balance and mobility for individuals with knee OA.

OBJECTIVE

The purpose of this study was to determine the convergent validity, known-groups validity, and test-retest reliability of a dynamic test of balance and mobility, the Community Balance and Mobility Scale (CB&M), in a knee OA population.

DESIGN

A cross-sectional design was used.

METHODS

Twenty-five individuals aged 50 years and older with medial knee OA and an equal number of healthy controls completed the CB&M and other tests of balance and mobility, including the Berg Balance Scale, the Timed "Up & Go" Test, a test of maximal single-leg stance time, and the 10-Meter Walk Test (self-selected and fast walking speed). Convergent validity of balance tests with the CB&M was assessed using Pearson product moment correlation coefficients, and known-groups validity was assessed using independent t tests. Test-retest reliability of the CB&M was assessed using intraclass correlation coefficients (ICCs) and standard error of measurement (SEM).

RESULTS

Scores on the CB&M were significantly correlated with all measures of balance and mobility for those with knee OA. There were significant differences in CB&M scores between groups. Scores on the CB&M were highly reliable in people with knee OA (ICC=.95, 95% confidence interval [95% CI]=0.70 to 0.99; SEM=3, 95% CI=2.68 to 4.67).

LIMITATIONS

Few participants had severe knee OA.

CONCLUSIONS

The CB&M displayed moderate convergent validity, excellent known-groups validity, and high test-retest reliability. The CB&M can be used as a valid and reliable tool to assess dynamic balance and mobility deficits in people with knee OA.

The hallmarks of osteoarthritis and the potential to develop personalised disease-modifying pharmacological therapeutics

Osteoarthritis (OA) is an age-related condition and the leading cause of pain, disability and shortening of adult working life in the UK. The incidence of OA increases with age, with 25% of the over 50s population having OA of the knee. Despite promising preclinical data covering various molecule classes, there is regrettably at present no approved disease-modifying OA drugs (DMOADs). With the advent of next generation sequencing technologies, other therapeutic areas, in particular oncology, have experienced a paradigm shift towards defining disease by its molecular composition. This paradigm shift has enabled high resolution patient stratification and supported the emergence of personalised or precision medicines. In this review we evaluate the potential for the development of OA therapeutics to undergo a similar paradigm shift given that OA is increasingly being recognised as a heterogeneous disease affecting multiple joint tissues. We highlight the evidence for the role of these tissues in OA pathology as different "hallmarks" of OA biology and review the opportunities to identify and develop targeted disease-modifying pharmacological therapeutics. Finally, we consider whether it is feasible to expect the emergence of personalised disease-modifying medicines for patients with OA and how this might be achieved.

Future directions in painful knee osteoarthritis: harnessing complexity in a heterogeneous population

This perspective article proposes a conceptual model for the pain experience for individuals diagnosed with knee osteoarthritis (OA). Pain in knee OA is likely a heterogeneous, multifactorial phenomenon that involves not only the OA disease process but also elements specific to patient psychology and pain neurophysiology. The relevant contributions to the pain experience for any individual patient remain difficult, if not impossible, to definitively determine, and the rationale for many clinical treatment decisions arises primarily from a mechanistic understanding of OA pathophysiology. The Osteoarthritis Research Society International (OARSI) recently identified "phenotyping" of OA pain as a research priority to "better target pain therapies to individual patients." This perspective article proposes that contributions from 3 domains--knee pathology, psychological distress, and pain neurophysiology--should be considered equally important in future efforts to understand pain phenotypes in knee OA. Ultimately, characterization of pain phenotypes may aid in the understanding of the pain experience and the development of interventions specific to pain for individual patients.

Vitamin D deficiency associates with γ-tocopherol and quadriceps weakness but not inflammatory cytokines in subjects with knee osteoarthritis

Knee osteoarthritis (OA) is a degenerative joint condition and a leading cause of physical disability in the United States. Quadriceps weakness and inflammatory cytokines contribute to the pathogenesis of knee OA, and both of which, increase with vitamin D deficiency. Other micronutrients, such as vitamins C and E and β-carotene, modulate inflammatory cytokines and decrease during inflammation. The purpose of this study was to test the hypothesis that vitamin D deficiency associates with quadriceps weakness, an increase in serum cytokines, and a decrease in circulating micronutrients in subjects with knee OA. Subjects (age, 48±1 y; serum 25(OH)D, 25.8±1.1 ng/mL) with knee OA were categorized as vitamin D deficient (n=17; serum 25(OH)D≤20 ng/mL), insufficient (n=21; serum 25(OH)D 20–29 ng/mL), or sufficient (n=18; serum 25(OH)D≥30 ng/mL). Single-leg strength (concentric knee extension–flexion contraction cycles at 60 °/s) and blood cytokine, carotene (α and β), ascorbic acid, and tocopherol (α and γ) concentrations were measured. Quadriceps peak torque, average power, total work, and deceleration were significantly (all p<0.05) impaired with vitamin D deficiency. Serum γ-tocopherol concentrations were significantly (p<0.05) increased with vitamin D deficiency. In the vitamin D sufficient group, γ-tocopherol inversely correlated (r=−0.47, p<0.05) with TNF-α, suggesting a pro-inflammatory increase with a γ-tocopherol decrease despite a sufficient serum 25(OH)D concentration. We conclude that vitamin D deficiency is detrimental to quadriceps function, and in subjects with vitamin D sufficiency, γ-tocopherol could have an important anti-inflammatory role in a pathophysiological condition mediated by inflammation.

•

We investigated the vitamin D association with mediators of knee osteoarthritis.

•

Vitamin D deficiency associated with quadriceps dysfunction.

•

Vitamin D deficiency was not associated with serum cytokines.

•

Vitamin D deficiency associated with increased plasma γ-tocopherol concentrations.

•

γ-Tocopherol inversely correlated with TNF-α in vitamin D sufficient subjects.

Exercise and osteoarthritis: cause and effects

Osteoarthritis (OA) is a common chronic joint condition predominantly affecting the knee, hip, and hand joints. Exercise plays a role in the development and treatment of OA but most of the literature in this area relates to knee OA. While studies indicate that exercise and physical activity have a generally positive effect on healthy cartilage metrics, depending upon the type of the activity and its intensity, the risk of OA development does appear to be moderately increased with sporting participation. In particular, joint injury associated with sports participation may be largely responsible for this increased risk of OA with sport. Various repetitive occupational tasks are also linked to greater likelihood of OA development. There are a number of physical impairments associated with OA including pain, muscle weakness and altered muscle function, reduced proprioception and postural control, joint instability, restricted range of motion, and lower aerobic fitness. These can result directly from the OA pathological process and/or indirectly as a result of factors such as pain, effusion, and reduced activity levels. These impairments and their underlying physiology are often targeted by exercise interventions and evidence generally shows that many of these can be modified by specific exercise. There is currently little clinical trial evidence to show that exercise can alter mechanical load and structural disease progression in those with established OA, although a number of impairments, that are amenable to change with exercise, appears to be associated with increased mechanical load and/or disease progression in longitudinal studies.

The relationship between quadriceps muscle weakness and worsening of knee pain in the MOST cohort: a 5-year longitudinal study

OBJECTIVE

To determine whether quadriceps weakness is associated with elevated risk of worsening knee pain over 5 years.

METHODS

The Multicenter Osteoarthritis Study (MOST) is a longitudinal study of 50-79-year-old adults with knee osteoarthritis (OA) or known risk factors for knee OA. The predictor variable was baseline isokinetic quadriceps strength. Covariates included baseline body mass index (BMI), physical activity level, and history of knee surgery. The outcome was worsening pain reported on the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index pain subscale or knee replacement surgery between baseline and 5-year follow-up. Analyses were knee-based and used generalized estimating equations, stratified by sex to assess whether the lowest compared with the highest tertile of baseline quadriceps strength was associated with an increased risk of worsening knee pain at 5-year follow-up, controlling for age, BMI, history of knee surgery, and physical activity level as well as correlation between knees within participants.

RESULTS

Analyses of worsening knee pain included 4,648 knees from 2,404 participants (61% female). Men with lower quadriceps strength did not have a higher risk of worsening knee pain (RR {95% CI} = 1.01 {0.78-1.32}, P = 0.9183). However, women in the lowest compared with the highest strength tertile had a 28% increased risk of worsening knee pain (RR {95% CI} = 1.28 {1.08-1.52}, P = 0.0052).

CONCLUSION

Quadriceps weakness was associated with an increased risk of worsening of knee pain over 5 years in women, but not in men.

Factors related to standing balance in patients with knee osteoarthritis

Objective

To assess factors related to standing balance in patients with knee osteoarthritis (OA).

Methods

In total, 37 female patients with painful knee OA were included. Pain, knee alignment, and Kellgren and Lawrence grade were evaluated accordingly. Static standing balance was measured with a force-platform system under two different conditions: static standing with eyes open (EO) and eyes closed (EC) for 30 seconds. The mean speed (mm/s) of movement of the center of pressure in the anteroposterior (AP) and mediolateral directions and the mean velocity moment (mm²/s) were analyzed for assessment of static balance.

Results

In the univariate regression analysis, age and knee alignment showed statistically significant relationships with the mean speed in the AP directions with EO. In the multiple linear regression model, age and knee alignment were positively associated and disease severity was negatively associated with mean speed in the AP directions with EO. However, the variables for EC static measurements were not significantly correlated with age, pain, knee alignment, or radiographic severity (p>0.05).

Conclusion

These findings show that the worse balance was associated with advanced age, less varus knee malalignment, and mild radiographic changes. Pain was not associated with standing balance.

Effects of acute joint effusion on balance in patients with knee osteoarthritis

OBJECTIVES

The purpose of this study was to assess the effects of acute joint effusion on balance in patients with knee osteoarthritis.

DESIGN

Forty-four female subjects with painful knee osteoarthritis participated in this single-blind, randomized, controlled clinical trial. All subjects were randomly assigned to either the injection or the control group. A volume of 20 ml of normal saline was injected into the knee joint cavity of the test subjects, who performed static and dynamic balance tests twice before and after joint infusion. The subjects in the control group performed the same tests without joint infusion. The outcome variables for static measurement were the mean speeds (millimeter per second) of the movement of the center of pressure in the mediolateral and anteroposterior directions and the mean velocity moment (square millimeter per second) with both eyes opened and eyes closed conditions. For dynamic measurement, time (second) and distance (millimeter) of the center of pressure were used.

RESULTS

Significant interaction of the balance-test variables (mean speeds, velocity moment, time, and distance) between the groups and time (P > 0.05) was not found. There were no significant differences between the groups in any of the balance-test variables (P > 0.05).

CONCLUSIONS

This study showed that acute joint effusion has no effect on static or dynamic postural sway in patients with knee osteoarthritis.

The proprioceptive senses: their roles in signaling body shape, body position and movement, and muscle force

This is a review of the proprioceptive senses generated as a result of our own actions. They include the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. Receptors involved in proprioception are located in skin, muscles, and joints. Information about limb position and movement is not generated by individual receptors, but by populations of afferents. Afferent signals generated during a movement are processed to code for endpoint position of a limb. The afferent input is referred to a central body map to determine the location of the limbs in space. Experimental phantom limbs, produced by blocking peripheral nerves, have shown that motor areas in the brain are able to generate conscious sensations of limb displacement and movement in the absence of any sensory input. In the normal limb tendon organs and possibly also muscle spindles contribute to the senses of force and heaviness. Exercise can disturb proprioception, and this has implications for musculoskeletal injuries. Proprioceptive senses, particularly of limb position and movement, deteriorate with age and are associated with an increased risk of falls in the elderly. The more recent information available on proprioception has given a better understanding of the mechanisms underlying these senses as well as providing new insight into a range of clinical conditions.

Determinants of pain and functioning in hip osteoarthritis - a two-year prospective study

OBJECTIVE

To identify predictors of pain and disability in hip osteoarthritis.

DESIGN

A prospective analysis of determinants of pain and functioning in hip osteoarthritis.

STUDY SETTING

Rehabilitation clinic in a central hospital.

PATIENTS

A total of 118 men and women aged 55-80 years who had radiologically diagnosed hip osteoarthritis and associated clinical symptoms and participated in a randomized controlled trial.

MAIN MEASURES

The self-reported disease-specific pain and physical function were assessed using the pain and functioning subscales of the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis index. The self-reported generic physical and mental functioning were assessed by using the Finnish-validated SF-36-item Health Survey RAND-36 subscales for function and physical and mental component summary scores. Outcome measures were recorded at 0, 3, 6, 12, 18 and 24 months.

RESULTS

Multivariate linear mixed model analyses revealed that lower disease-specific pain score and better functioning (WOMAC) were predicted by higher educational level (9.61 (3.15 to 16.07); 9.07 (2.05 to 16.09)), supervised exercise training (-10.13 (-17.87 to -2.39); -11.58 (-19.40 to -3.77)), habitual conditioning physical activity (-0.48 (-0.96 to -0.01); -0.39 (-0.84 to 0.05)), absence of comorbidities (-6.30 (-12.35 to -0.24); -7.87 (-14.45 to -1.30)) and absence of additional knee osteoarthritis (-7.62 (-13.87 to -1.36); -8.02 (-14.81 to -1.23)), respectively. The same factors, except for the comorbidities, also predicted general physical functioning score (RAND-36).

CONCLUSIONS

Higher education, absence of knee osteoarthritis and comorbidities, supervised exercise training and habitual conditioning physical activity predicted a lower presence of pain and better functional status in patients with hip osteoarthritis.

Local and systemic cardiovascular effects from monochromatic infrared therapy in patients with knee osteoarthritis: a double-blind, randomized, placebo-controlled study

Infrared (IR) therapy is used for pain relief in patients with knee osteoarthritis (OA). However, IR's effects on the cardiovascular system remain uncertain. Therefore, we investigated the local and systemic cardiovascular effects of monochromatic IR therapy on patients with knee OA in a double-blind, randomized, placebo-controlled study. Seventy-one subjects with knee OA received one session of 40 min of active or placebo monochromatic IR treatment (with power output of 6.24 W, wavelength of 890 nm, power density of 34.7 mW/cm² for 40 min, total energy of 41.6 J/cm² per knee per session) over the knee joints. Heart rate, blood pressure, and knee arterial blood flow velocity were periodically assessed at the baseline, during, and after treatment. Data were analyzed by repeated-measure analysis of covariance. Compared to baseline, there were no statistically significant group x time interaction effects between the 2 groups for heart rate (P = 0.160), blood pressure (systolic blood pressure: P = 0.861; diastolic blood pressure: P = 0.757), or mean arterial blood flow velocity (P = 0.769) in follow-up assessments. The present study revealed that although there was no increase of knee arterial blood flow velocity, monochromatic IR therapy produced no detrimental systemic cardiovascular effects.

The effect of a prehabilitation exercise program on quadriceps strength for patients undergoing total knee arthroplasty: a randomized controlled pilot study

OBJECTIVE

To examine the effect of a 6-week prehabilitation exercise training program on presurgical quadriceps strength for patients undergoing total knee arthroplasty (TKA).

DESIGN

Two-arm, parallel, randomized, controlled pilot trial.

SETTING

Private exercise space in a research facility.

PARTICIPANTS

Twenty-two patients scheduled for primary TKA.

METHODS

Participants completed a series of baseline questionnaires (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], Short Form 36, and Arthritis Self-efficacy Scale) and functional testing (isometric quadriceps strength assessment, flat-surface walk test, and stair ascent-descent test). The participants were randomized to a lower-body strength training program or to a nonspecific upper-body strength training program. The participants exercised 3 times per week for 6 weeks before TKA. Postintervention assessment occurred immediately before TKA, with follow-up assessments at 6 and 12 weeks after surgery.

OUTCOMES

The primary outcome was isometric quadriceps strength. Secondary outcomes were mobility, pain, self-reported function, health-related quality of life, and arthritis self-efficacy.

RESULTS

There was no significant treatment condition-by-time effect on quadriceps strength, but the effect size was large (F(3,18) = 0.89, P = .47, η(2) = 0.13). Similar findings were shown for walking speed (F(3,18) = 1.47, P = .26, η(2) = 0.20). There was a significant treatment-by-time effect for the Short Form 36 mental component score (F(3,18) = 0.41, P = .02, η(2) = 0.41), with differences emerging before surgery but not at either postoperative assessment. For all other secondary outcome measures, the treatment-by-time effect was nonsignificant and small.

CONCLUSION

The intervention elicited clinically meaningful increases in quadriceps strength, walking speed, and mental health immediately before TKA. It did not impart lasting benefits to patients in the 12 weeks after surgery. Analysis of the results suggests that quadriceps strength may not drive functional improvements after surgery. These findings need to be replicated in larger trials before clinical recommendations are made about including strength training prehabilitation in everyday practice.