Effect of knee pain on joint loading in patients with osteoarthritis

Biomechanical improvements in gait following medial pivot knee implant surgery

BACKGROUND

Total knee replacements are used to improve function and reduce pain in patients with advanced osteoarthritis. The medially stabilising implant is designed to mimic a healthy knee. This study aims to provide a comprehensive analysis of the kinematics and kinetics of a medially stabilising knee implant, comparing it to a healthy control group, as well as to its pre-operative state and the contralateral limb.

METHODS

Sixteen total knee replacement patients and ten healthy participants were recruited. Patients underwent testing 4-6 weeks before surgery and repeated the same tests 12 months after surgery. Healthy participants completed the same tests at a single time point. All participants completed three walking trials: kinematics was captured with eight cameras; kinetics with in-ground force plates. Subject-specific musculoskeletal models were developed in OpenSim. Inverse kinematics and inverse dynamics were used to determine gait parameters. Joint angles and joint moments were evaluated using Statistical Parametric Mapping. Patient-reported outcome measures were also collected at both time points.

FINDINGS

Spatiotemporal results indicate significant differences in velocity and step length between pre-operative patients and control participants. Differences are observed in the adduction angles between the contralateral and ipsilateral limbs pre-operatively. Postoperatively, there was an increase in the 1st peak flexion moment, reduced adduction moment and reduced internal rotation moment. In PROMs, patients all report improvements in pain levels and high satisfaction levels following surgery.

INTERPRETATIONS

Following medial stabilising total knee arthroplasty, patients displayed improved clinical parameters and joint moments reflecting a shift towards more normal, healthy gait.

Different types of foot orthoses effect on gait mechanics in patients with rheumatoid arthritis

Foot orthoses are a first line conservative treatment for foot impairments in patients with rheumatoid arthritis (RA), however their effect on gait mechanics is poorly understood. We aimed to compare changes in lower limb and foot mechanics between two types of commonly used foot orthoses (FO) with a control. Twenty-seven patients with rheumatoid arthritis participated in this crossover study. Two different types of FO (a medially wedged custom-made FO and a prefabricated FO with a metatarsal dome, respectively), were compared against a control insole. During gait, lower limb mechanics were analyzed using 3D motion capture, force plates, and an in-shoe pressure system. Inverse dynamics models were created in the Anybody Modeling System to calculate joint angles and joint moments during gait. Gait variables were analyzed using statistical parametric mapping. Compared to the control, the prefabricated FO had limited effect on gait mechanics. Compared to the control the custom-made FO reduced ankle plantarflexion moment with 0.4 %body weight * body height (BW * BH) between 66 and 76% of stance and ankle eversion moment was reduced 0.16% BW*BH between 3 and 40% of stance. Furthermore, it also reduced the average forefoot plantar pressure by 9 kPa between 20 and 62% of stance compared to the control. Changes in foot pressure distribution, joint moments and angles were most pronounced for custom-made FO compared to the prefabricated FO. The findings suggest that patients with RA and foot impairments may benefit more from an individualized FO strategy, if the aim of the treatment is to alter gait mechanics. (NCT03561688).

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.

Younger Total Knee Replacement Patients Do Not Demonstrate Gait Asymmetry for Heel Strike Transient or Knee Joint Moments That Are Observed in Older Patients

Gait asymmetry is observed after total knee replacement, often leading to excessive forces at the contralateral limb. The number of total knee replacement procedures has increased substantially over the past 2 decades, particularly among younger patients. Relatively little is known regarding these younger patients (<65 y), specifically, with respect to gait asymmetry. The purpose of this study was to investigate if age affects gait asymmetry after unilateral total knee replacement. Three-dimensional analysis of 10 walking trials was collected from the following 4 groups: younger patient (age: 54.3 [7.9] y), younger control (age: 55.2 [4.0] y), older patient (age: 76.9 [4.7] y), and older control (age: 77.7 [4.1] y). The older patients, but not any of the other groups, demonstrated a significantly larger heel strike transient and peak knee adduction moment at the nonsurgical compared with the surgical limb. The observed gait pattern of the younger patients resembled that of the younger controls, rather than the older patients. The greater loading of the nonsurgical limb for the older patients could contribute to the initiation or further progression of osteoarthritic degeneration in the contralateral knee; these asymmetries were not observed for the younger patients.

Relationships between varus-valgus laxity of the severely osteoarthritic knee and gait, instability, clinical performance, and function

Increased varus-valgus laxity has been reported in individuals with knee osteoarthritis (OA) compared to controls. However, the majority of previous investigations may not report truly passive joint laxity, as their tests have been performed on conscious participants who could be guarding against motion with muscle contraction during laxity evaluation. The purpose of this study was to investigate how a measure of passive knee laxity, recorded when the participant is under anesthesia, is related to varus-valgus excursion during gait, clinical measures of performance, perceived instability, and self-reported function in participants with severe knee OA. We assessed passive varus-valgus knee laxity in 29 participants (30 knees) with severe OA, as they underwent total knee arthroplasty (TKA). Participants also completed gait analysis, clinical assessment of performance (6-min walk (6 MW), stair climbing test (SCT), isometric knee strength), and self-reported measures of function (perceived instability, Knee injury, and Osteoarthritis Outcome Score (KOOS) a median of 18 days before the TKA procedure. We observed that greater passive varus-valgus laxity was associated with greater varus-valgus excursion during gait (R2  = 0.34, p = 0.002). Significant associations were also observed between greater laxity and greater isometric knee extension strength (p = 0.014), farther 6 MW distance (p = 0.033) and shorter SCT time (p = 0.046). No relationship was observed between passive varus-valgus laxity and isometric knee flexion strength, perceived instability, or any KOOS subscale. The conflicting associations between laxity, frontal excursion during gait, and functional performance suggest a complex relationship between laxity and knee cartilage health, clinical performance, and self-reported function that merits further study. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1644-1652, 2017.

Strategies to reduce joint load in the medial compartment of the knee during gait in individuals with osteoarthritis: a review of the literature

Abstract Introduction: Increased joint load on the medial compartment of the knee during gait is a mechanical factor responsible for pain and progression of medial knee osteoarthritis. The knee external adductor moment of force is a kinetic parameter that correlates with the joint load in the medial compartment. Objective: The aim of this study was to conduct a narrative review of the biomechanics strategies during gait of individuals with medial knee osteoarthritis that reduce external adductor moment of force of the knee. Methods: The review of the literature was conducted in the databases MEDLINE, PUBMED and PEDro and included articles published between 2000 and 2011. It was selected transversal, theoretical, correlational and longitudinal studies as well as controlled clinical trials. Results: Decreased gait velocity, increased external rotation of the foot, increased internal abductor moment force of the hip and lateral trunk inclination to the side of the support limb are compensatory strategies used to reduce the external adductor moment of force of the knee during gait of individuals with medial knee osteoarthritis. The lateral trunk inclination may be beneficial in a short term, however it decreases the activity of the abductors muscles of the hip during the support phase of the gait favoring compensation that could result in the progression of medial knee osteoarthritis. Conclusion: Strengthening of the abductors muscles of the hip reduces pain, improves the function and prevents compensations that in a long term could possibly accelerate the progression of the medial knee osteoarthritis.

Ankle motion influences the external knee adduction moment and may predict who will respond to lateral wedge insoles?: an ancillary analysis from the SILK trial

OBJECTIVE

Lateral wedge insoles are a potential simple treatment for medial knee osteoarthritis (OA) patients by reducing the external knee adduction moment (EKAM). However in some patients, an increase in their EKAM is seen. Understanding the role of the ankle joint complex in the response to lateral wedge insoles is critical in understanding and potentially identifying why some patients respond differently to lateral wedge insoles.

METHOD

Participants with medial tibiofemoral OA underwent gait analysis whilst walking in a control shoe and a lateral wedge insole. We evaluated if dynamic ankle joint complex coronal plane biomechanical measures could explain and identify those participants that increased (biomechanical non-responder) or decreased (biomechanical responder) EKAM under lateral wedge conditions compared to the control shoe.

RESULTS

Of the 70 participants studied (43 male), 33% increased their EKAM and 67% decreased their EKAM. Overall, lateral wedge insoles shifted the centre of foot pressure laterally, increased eversion of the ankle/subtalar joint complex (STJ) and the eversion moment compared to the control condition. Ankle angle at peak EKAM and peak eversion ankle/STJ complex angle in the control condition predicted if individuals were likely to decrease EKAM under lateral wedge conditions.

CONCLUSIONS

Coronal plane ankle/STJ complex biomechanical measures play a key role in reducing EKAM when wearing lateral wedge insoles. These findings may assist in the identification of those individuals that could benefit more from wearing lateral wedge insoles.

The influence of visual feedback on the mental representation of gait in patients with THR: a new approach for an experimental rehabilitation strategy

Due to total hip replacement (THR), patients reveal abnormal gait patterns which post-operative do often not return to "normal". The restoration towards normal gait reduces stress on the adjacent joints which consequently reduces risk of osteoarthrosis development. Motor-performance is related to the structure of the movement in long-term memory, thus it seems to be essential to imprint correct gait patterns in there. Mental representation structures can develop over the course of training and visual feedback presumably helps regaining a better representation of gait in long-term memory. The purpose of this study is to evaluate the effect of visual feedback on mental representation in patients with THR. In a randomized controlled trial, 20 women (57 ± 6 years) with THR have been enrolled. Subjects were randomly assigned to a control group (CG) or intervention group (IG). Additionally to inpatient treatment, all subjects participated in a standardized gait training including either an intervention based on verbal information from a physiotherapist (CG) or an intervention based on real-time visual feedback (IG). Mental representation was measured in pre-test and post-test using the structure-dimensional analysis. Results indicate significant improvements in mental representation of gait in the post-test only in IG, suggesting that beneficial effects were provoked by visual feedback.

Is there a causal link between knee loading and knee osteoarthritis progression? A systematic review and meta-analysis of cohort studies and randomised trials

OBJECTIVE

We performed a systematic review, meta-analysis and assessed the evidence supporting a causal link between knee joint loading during walking and structural knee osteoarthritis (OA) progression.

DESIGN

Systematic review, meta-analysis and application of Bradford Hill's considerations on causation.

DATA SOURCES

We searched MEDLINE, Scopus, AMED, CINAHL and SportsDiscus for prospective cohort studies and randomised controlled trials (RCTs) from 1950 through October 2013.

STUDY ELIGIBILITY CRITERIA

We selected cohort studies and RCTs in which estimates of knee joint loading during walking were used to predict structural knee OA progression assessed by X-ray or MRI.

DATA ANALYSES

Meta-analysis was performed to estimate the combined OR for structural disease progression with higher baseline loading. The likelihood of a causal link between knee joint loading and OA progression was assessed from cohort studies using the Bradford Hill guidelines to derive a 0-4 causation score based on four criteria and examined for confirmation in RCTs.

RESULTS

Of the 1078 potentially eligible articles, 5 prospective cohort studies were included. The studies included a total of 452 patients relating joint loading to disease progression over 12-72 months. There were very serious limitations associated with the methodological quality of the included studies. The combined OR for disease progression was 1.90 (95% CI 0.85 to 4.25; I(2)=77%) for each one-unit increment in baseline knee loading. The combined causation score was 0, indicating no causal association between knee loading and knee OA progression. No RCTs were found to confirm or refute the findings from the cohort studies.

CONCLUSIONS

There is very limited and low-quality evidence to support for a causal link between knee joint loading during walking and structural progression of knee OA.

TRIAL REGISTRATION NUMBER

CRD42012003253.

Early knee osteoarthritis management should first address mechanical joint overload

Early knee osteoarthritis poses a therapeutic dilemma to the musculoskeletal clinician. Despite the recent interest in arthroscopic and injectable regenerative therapies intended to repair or restore a focal target such as cartilage, meniscus, or subchondral bone, none have been shown to slow disease progression. A likely cause of these disappointing treatment outcomes is the failure to address chronic and excessive loading of the knee joint. A growing body of evidence suggests that first-line therapies for early knee osteoarthritis should emphasize unloading the knee joint since any potential therapeutic benefit of regenerative therapies will likely be attenuated by excessive mechanical demand at the knee joint. Minimally invasive medical devices such as patient-specific interpositional implants and extracapsular joint unloading implants are currently in development to address this clinical need.

Effect of exercise and gait retraining on knee adduction moment in people with knee osteoarthritis

The knee adduction moment represents the medial knee joint load, and greater value is associated with higher load. In people with knee osteoarthritis, it is important to apply proper treatment with the least side effects to reduce knee adduction moment and, consequently, reduce medial knee joint load. This reduction may slow the progression of knee osteoarthritis. The research team performed a literature search of electronic databases. The search keywords were as follows: knee osteoarthritis, knee adduction moment, exercise program, exercise therapy, gait retraining, gait modification and knee joint loading. In total, 12 studies were selected, according to the selection criteria. Findings from previous studies illustrated that exercise and gait retraining programs could alter knee adduction moment in people with knee osteoarthritis. These treatments are noninvasive and nonpharmacological which so far have no or few side effects, as well as being low cost. The results of this review revealed that gait retraining programs were helpful in reducing the knee adduction moment. In contrast, not all the exercise programs were beneficial in reducing knee adduction moment. Future studies are needed to indicate best clinical exercise and gait retraining programs, which are most effective in reducing knee adduction moment in people with knee osteoarthritis.

Quality of life in patients with knee osteoarthritis: a commentary on nonsurgical and surgical treatments

Knee osteoarthritis (OA) has a significant negative impact on health-related quality of life (HRQoL). Identification of therapies that improve HRQoL in patients with knee OA may mitigate the clinical, economic, and social burden of this disease. The purpose of this commentary is to report the impact of knee OA on HRQoL, describe the change in HRQoL attributable to common knee OA interventions, and summarize findings from clinical trials of a promising therapy. Nonsurgical therapies do not reliably modify HRQoL in knee OA patients given their general inability to alleviate physical manifestations of OA. Surgical knee OA interventions generally result in good to excellent patient outcomes. However, there are significant barriers to considering surgery, which limits clinical utility. Therapies that most effectively control OA-related pain with a low risk: benefit ratio will likely have the greatest benefit on HRQoL with greater rates of patient adoption. Initial clinical trial findings suggest that less invasive joint unloading implants hold promise in bridging the therapeutic gap between nonsurgical and surgical treatments for the knee OA patient.

The KineSpring(®) Knee Implant System: an implantable joint-unloading prosthesis for treatment of medial knee osteoarthritis

Symptomatic medial compartment knee osteoarthritis (OA) is the leading cause of musculoskeletal pain and disability in adults. Therapies intended to unload the medial knee compartment have yielded unsatisfactory results due to low patient compliance with conservative treatments and high complication rates with surgical options. There is no widely available joint-unloading treatment for medial knee OA that offers clinically important symptom alleviation, low complication risk, and high patient acceptance. The KineSpring^® Knee Implant System (Moximed, Inc, Hayward, CA, USA) is a first-of-its-kind, implantable, extra-articular, extra-capsular prosthesis intended to alleviate knee OA-related symptoms by reducing medial knee compartment loading while overcoming the limitations of traditional joint-unloading therapies. Preclinical and clinical studies have demonstrated excellent prosthesis durability, substantial reductions in medial compartment and total joint loads, and clinically important improvements in OA-related pain and function. The purpose of this report is to describe the KineSpring System, including implant characteristics, principles of operation, indications for use, patient selection criteria, surgical technique, postoperative care, preclinical testing, and clinical experience. The KineSpring System has potential to bridge the gap between ineffective conservative treatments and irreversible surgical interventions for medial compartment knee OA.

Midterm Outcomes and Predictors of Clinical Success With the KineSpring Knee Implant System

The purpose of this study was to (1) evaluate joint pain and function in knee osteoarthritis (OA) patients treated with a joint-sparing, extracapsular implant and (2) identify patient characteristics that influenced clinical outcomes. This study included 99 patients with symptomatic medial knee OA refractory to conservative care who were treated with the KineSpring Knee Implant System and followed for a mean of 17 months (range, 1.5 to 48 months). All devices were successfully implanted and activated with no intraoperative complications. Statistically significant mean improvements of 56%, 50%, and 38% were observed for Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, Function, and Stiffness scales, respectively (all P < 0.001). Regardless of gender, age group, body mass index classification, or disease severity, all WOMAC domain scores significantly improved during the postoperative follow-up period. WOMAC clinical success rates were 77.8% for Pain, 77.8% for Function, and 68.7% for Stiffness. Neither gender, age group, body mass index classification, nor disease severity predicted clinical success in any WOMAC domain. In conclusion, the KineSpring System yields clinically meaningful improvements in joint pain and function in patients with medial knee OA. Additionally, unlike joint-altering procedures such as knee arthroplasty or high tibial osteotomy, patient characteristics had little association with postoperative clinical outcomes.

Conservative management of symptomatic knee osteoarthritis: a flawed strategy?

Conservative management of medial compartment knee osteoarthritis (OA) is a misleading term used to describe the application of medical, orthotic, and/or rehabilitative therapies exclusive of surgical interventions. The implication of this nomenclature is that these therapies offer satisfactory symptom relief, alter disease progression, and have limited side effects. Unfortunately, conservative therapeutic options possesses few, if any, characteristics of an ideal treatment, namely one that significantly alleviates pain, improves knee function, and reduces medial compartmental loading without adverse side effects. As uncompensated mechanical loading is a primary culprit in the development and progression of knee OA, we propose that the therapeutic perspective of conservative treatment should shift from pharmacological treatments, which have no influence on joint loading, minimal potential to alter joint function, substantial associated risks, and significant financial costs, towards minimally invasive load absorbing therapeutic interventions. A safe and effective minimally invasive medical device specifically engineered for symptomatic relief of medial knee OA by limiting joint contact forces has the potential to reduce the clinical and economic knee OA burden. This review characterizes the current standard of care recommendations for conservative management of medial compartment knee OA with respect to treatment efficacy, risk profile, and economic burden.

Protocol for constructing subject-specific biomechanical models of knee joint

A robust protocol for building subject-specific biomechanical models of the human knee joint is proposed which uses magnetic resonance imaging, motion analysis and force platform data in conjunction with detailed 3D finite element models. The proposed protocol can be used for determining stress and strain distributions and contact kinetics in different knee elements at different body postures during various physical activities. Several examples are provided to highlight the capabilities and potential applications of the proposed protocol. This includes preliminary results on the role of body weight on the stresses and strains induced in the knee articular cartilages and meniscus during single-leg stance and calculations of the induced stresses and ligament forces during the gait cycle.

The KineSpring load absorber implant: rationale, design and biomechanical characterization

Osteoarthritis (OA) of the knee is the leading cause of disability in the adult population. Although a number of treatments for knee OA are available, none effectively prevent OA progression. Currently, a wide therapeutic gap exists for patients who have unsuccessfully exhausted conservative OA treatments but who are hesitant or ineligible to undergo invasive surgery. The KineSpring device is a novel, joint preserving, minimally invasive implant that reduces medial compartment loading without significantly impacting the loading of the lateral compartment. This article describes the rationale for and the design of the KineSpring device and summarizes results of initial biomechanical testing in an OA cadaver model.

Clinical and economic consequences of the treatment gap in knee osteoarthritis management

Osteoarthritis affects 27 million American adults of all ages and is a leading cause of disability in middle-aged and older adults. Initial management of knee osteoarthritis symptoms utilizes conservative care although long-term efficacy is poor. Arthroplasty and high tibial osteotomy may be considered for patients with severe pain or disability. We hypothesize that a distinct treatment gap exists for the patient with symptomatic knee osteoarthritis who is unresponsive to conservative care (including simple surgical treatments) yet refuses to undergo or is not an appropriate candidate for more invasive surgical procedures. This treatment gap represents a protracted period in which the patient experiences debilitating pain, reduced quality of life, and a significant financial burden. Approximately 3.6 million Americans linger in the knee osteoarthritis treatment gap and this number will grow to about 5 million people by 2025. The typical knee osteoarthritis treatment gap extends 20 years although the younger osteoarthritis patient is faced with the treatment gap throughout the majority of their adult life. There is great need for a safe, effective, and cost effective treatment option for patients with moderate to severe osteoarthritis that enjoys high patient acceptance.

Robust features of knee osteoarthritis in joint moments are independent of reference frame selection

BACKGROUND

changes in lower-limb joint moments are important outcome measures for treatment and prevention of knee osteoarthritis. However, it is known that both the magnitude and amplitude of joint moments are affected by the choice of anatomical reference frame. The purpose of this study was to identify features of joint moment waveforms that, regardless of the choice of reference frame, are different for subjects with knee osteoarthritis as compared to asymptomatic control subjects.

METHODS

external joint moments during the stance phase of gait were calculated for 44 subjects with moderate knee osteoarthritis and 44 asymptomatic subjects. Moments were then expressed using four anatomical reference frames: Joint Coordinate System, Plane of Progression, Proximal, and Distal. Principal component analysis was used to extract features of the moment waveforms that differed between control and osteoarthritis groups across all reference frames.

FINDINGS

principal component analysis revealed that, regardless of the choice of reference frame, subjects with knee osteoarthritis exhibited significantly decreased overall hip adduction moment magnitudes, increased overall knee adduction moment magnitudes, decreased knee internal rotation moment amplitudes, and increased early-stance ankle adduction magnitudes.

INTERPRETATION

the four robust features identified in this study are sensitive to the effect of knee osteoarthritis, but independent of changes in the anatomical reference frame. These features can be solely attributed to the pathogenesis of the disease, and not to the artifact of reference frame selection.

Exercise for people with hip or knee osteoarthritis: a comparison of land-based and aquatic interventions

Expert opinion considers the referral of people with osteoarthritis (OA) for physiotherapy to be a core component of managing the functional disability and pain of the disease. Clinical guidelines for the physiotherapy management of people with OA focus on three main areas: exercise, pain relief, and specific manual therapy techniques. Land-based group and individual physiotherapy exercise programs, as well as manual therapy, have demonstrated a distinct benefit in favor of physiotherapy intervention. Similarly, both general and specific aquatic physiotherapy exercise programs have shown positive outcomes for people with OA. This review will focus primarily on therapeutic exercise to improve strength and fitness and reduce pain in people with hip or knee OA. An overview of the principles of hydrodynamics relevant to aquatic exercise is also included to facilitate an understanding of effective aquatic exercise programs. The issue of compliance with exercise programs will also be discussed. Clinicians will, therefore, gain an understanding of the benefits of land-based and aquatic exercise for people with OA.

Effects of common footwear on joint loading in osteoarthritis of the knee

OBJECTIVE

Elevated joint loads during walking have been associated with the severity and progression of osteoarthritis (OA) of the knee. Footwear may have the potential to alter these loads. This study compares the effects of several common shoe types on knee loading in subjects with OA of the knee.

METHODS

Thirty-one subjects (10 men, 21 women) with radiographic and symptomatic knee OA underwent gait analyses using an optoelectronic camera system and multicomponent force plate. In each case, gait was evaluated during barefoot walking and while wearing 4 different shoe types: 1) clogs, 2) stability shoes, 3) flat walking shoes, and 4) flip-flops. Peak knee loads were compared between the different footwear conditions.

RESULTS

Overall, the clogs and stability shoes resulted in a significantly higher (approximately 15% higher) peak knee adduction moment (mean +/- SD 3.1 +/- 0.7 and 3.0 +/- 0.7 divided by body weight [BW] x height [H] multiplied by 100, respectively; P < 0.05) compared with that of flat walking shoes (mean +/- SD 2.8 +/- 0.7 %BW x H), flip-flops (mean +/- SD 2.7 +/- 0.8 %BW x H), and barefoot walking (mean +/- SD 2.7 +/- 0.7 %BW x H). There were no statistically significant differences in knee loads with the flat walking shoes and flip-flops compared with barefoot walking.

CONCLUSION

These data confirm that footwear may have significant effects on knee loads during walking in subjects with OA of the knee. Flexibility and heel height may be important differentiating characteristics of shoes that affect knee loads. In light of the strong relationship between knee loading and OA, the design and biomechanical effects of modern footwear should be more closely evaluated in terms of their effects on the disease.

Effect of a home program of hip abductor exercises on knee joint loading, strength, function, and pain in people with knee osteoarthritis: a clinical trial

BACKGROUND

Hip abductor muscle weakness may result in impaired frontal-plane pelvic control during gait, leading to greater medial compartment loading in people with knee osteoarthritis (OA).

OBJECTIVE

This study investigated the effect of an 8-week home strengthening program for the hip abductor muscles on knee joint loading (measured by the external knee adduction moment during gait), strength (force-generating capacity), and function and pain in individuals with medial knee OA.

DESIGN

The study design was a nonequivalent, pretest-posttest, control group design.

SETTING

Testing was conducted in a motor performance laboratory.

PATIENTS

An a priori sample size calculation was performed. Forty participants with knee OA were matched for age and sex with a control group of participants without knee OA.

INTERVENTION

Participants with knee OA completed a home hip abductor strengthening program.

MEASUREMENTS

Three-dimensional gait analysis was performed to obtain peak knee adduction moments in the first 50% of the stance phase. Isokinetic concentric strength of the hip abductor muscles was measured using an isokinetic dynamometer. The Five-Times-Sit-to-Stand Test was used to evaluate functional performance. Knee pain was assessed with the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire.

RESULTS

Following the intervention, the OA group demonstrated significant improvement in hip abductor strength, but not in the knee adduction moment. Functional performance on the sit-to-stand test improved in the OA group compared with the control group. The OA group reported decreased knee pain after the intervention.

LIMITATIONS

Gait strategies that may have affected the knee adduction moment, including lateral trunk lean, were not evaluated in this study.

CONCLUSIONS

Hip abductor strengthening did not reduce knee joint loading but did improve function and reduce pain in a group with medial knee OA.

Medial knee joint loading increases in those who respond to hyaluronan injection for medial knee osteoarthritis

Knee osteoarthritis (OA) is a cause of decline in function and the medial compartment is often affected. Intraarticular injection of hyaluronic acid (HA) is indicated as a symptom modifying treatment with at least 6 months passing between consecutive injection series. The effects of HA injection on gait variables have not been extensively examined. Therefore, our objective was to investigate the effects of HA injection on gait in people with medial knee OA. Twenty-seven subjects were included; each was tested prior to treatment (baseline), no later than 3 weeks following the last injection (post-HA), and again 5 months after treatment ended (follow-up). Responder criteria were defined to identify responders and non-responders. Subjects underwent 3D gait analysis, muscle activity was sampled, and co-contraction indices were calculated. Responders experienced increased peak knee adduction moments post-HA, whereas non-responders did not. Improved self-report scores were associated with increased knee adduction moments and increased medial co-contraction. Pain relief may result in higher loading onto the already vulnerable medial compartment due to changes in lower limb mechanics and muscle activation patterns. Eventually this may result in a more rapid progression of joint deterioration.

Assessment of kinematic and kinetic patterns following limb salvage procedures for bone sarcoma

Bone sarcomas are the fourth most common cancer in individuals under 25 years. Limb salvage procedures have become increasingly popular for the treatment of osteosarcomas as they have functional and psychological benefits over traditional amputative procedures. The purpose of this paper was to evaluate kinematic and kinetic characteristics of patient's post-limb salvage and examine key predictive factors of gait dysfunction. A retrospective outcome study was undertaken on 20 limb salvage patients (10 females, 10 males) recruited from the Queensland Bone Tumour Registry. Kinematic and kinetic data were collected using a 3D motional analysis system and three force platforms. Loading response knee flexion in the affected lower limb was reduced compared to the unaffected lower limb (P<0.001) and the control group (P<0.001), although, closer examination of results showed two contrasting patterns of knee flexion during loading. Multiple regression analysis showed that muscular integrity (i.e. strength, ROM and residual mass) was the most predictive factor of function following limb salvage surgery. ANOVA showed that patients treated with the Stanmore SIMLES prostheses exhibited superior torque and power production at the ankle during late stance compared to those treated with the Stryker HMRS. In summary, the results showed that limb salvage patients adopted a gait pattern that reduced the moment demand at the knee and hip, suggesting a compensation for pain, reduced stability and/or muscle weakness.

The responsiveness of three-dimensional knee accelerations used as an estimation of knee instability and loading transmission during gait in osteoarthritis patient's follow-up

OBJECTIVE

Knee instability and joint loading transmission are two important biomechanical factors in subjects with knee osteoarthritis (OA). However, the relationship between these factors in a rehabilitation treatment remains unclear. The purpose of this study is to determine the responsiveness of a new three-dimensional (3D) acceleration method used as an estimation of knee instability and joint loading transmission during gait in OA subjects after a rehabilitation treatment.

METHOD

Twenty-four subjects with medial knee OA were included in this study. They had clinical and gait evaluations before and after 12 weeks of treatment. 3D linear knee accelerations, quadriceps and hamstring isometric strength and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) pain were quantified, and compared between both evaluations. Nine asymptomatic subjects participated in this study for gait comparison.

RESULTS

A significant reduction of the anterior posterior (AP) knee acceleration peak (P=0.02) had been detected after the treatment. No difference for both distal and lateral knee accelerations peak was found. A significant increase in quadriceps (P<0.001) and hamstring (P=0.006) strength was seen after treatment. The WOMAC of pain had shown significant reduction after the treatment (P<0.001).

CONCLUSION

The present study demonstrates that the estimation of knee acceleration parameters is sensitive to changes in knee OA gait after a rehabilitation treatment. This study also indicates that a treatment of 3 months which combines therapeutic and exercises program could have benefits on knee OA by increasing AP knee stability and stabilize joint loading transmission during gait.

Proximal gait adaptations in medial knee OA

The purpose of this study was to examine interlimb differences in gait kinematics and kinetics in patients with symptomatic medial knee OA. The main objective was to identify hip joint movement strategies that might lower the knee adduction moment and also compensate for decreased knee flexion during weight acceptance. Gait analysis was performed on 32 patients with moderate medial compartment knee OA. Kinetic and kinematic data were calculated and side-to-side comparisons made. Radiographs were used to identify frontal plane alignment. No interlimb difference in the peak knee adduction moment was found (p = 0.512), whereas a greatly reduced hip adduction moment was seen on the involved side (p < 0.001) during the early part of stance. The involved limb flexed significantly less and hip and knee flexion moments were smaller compared to the uninvolved side. Gait adaptations involving a lateral sway of the trunk may successfully lead to relatively lower ipsilateral knee adduction moments, and would further be reflected by a lower adduction moment at the hip. Subjects did not compensate for less knee flexion by any dynamic means, and likely experience a resulting higher joint impact. These gait adaptations may have implications with respect to development of weakness of the ipsilateral hip musculature and progression of multiarticular OA.

A mechanical theory for the effectiveness of bracing for medial compartment osteoarthritis of the knee

BACKGROUND

Evidence that knee braces used for the treatment of osteoarthritis mediate pain relief and improve function by unloading the joint (increasing the joint separation) remains inconclusive. Alternatively, valgus-producing braces may mediate pain relief by mechanically stabilizing the joint and reducing muscle cocontractions and joint compression. In this study, therefore, we sought to examine the degree to which so-called unloader braces control knee instability and influence muscle cocontractions during gait.

METHODS

Sixteen subjects with radiographic evidence of knee malalignment and medial compartment osteoarthritis were recruited and fitted with a custom Generation II Unloader brace. Gait analysis was performed without use of the brace and with the brace in neutral alignment and in 4 degrees of valgus alignment. A two-week washout period separated the brace conditions. Muscle cocontraction indices were derived for agonist and antagonist muscle pairings. Pain, instability, and functional status were obtained with use of self-reported questionnaires, and the results were compared.

RESULTS

The scores for pain, function, and stability were worst when the knee was unsupported (the baseline and washout conditions). At baseline, nine of the sixteen patients reported knee instability and five of the nine complained that it affected their activities of daily living. Poor knee stability was found to be correlated with low ratings for the activities of daily living, quality of life, and global knee function and with increased pain and symptoms. Knee function and stability scored best with the brace in the neutral setting compared with the brace in the valgus setting. The cocontraction of the vastus lateralis-lateral hamstrings was significantly reduced from baseline in both the neutral (p = 0.014) and valgus conditions (p = 0.023), and the cocontraction of the vastus medialis-medial hamstrings was significantly reduced with the valgus setting (p = 0.068), as a result of bracing. Patients with greater varus alignment had greater decreases in vastus lateralis-lateral hamstring muscle cocontraction.

CONCLUSIONS

When knees with medial compartment osteoarthritis are braced, neutral alignment performs as well as or better than valgus alignment in reducing pain, disability, muscle cocontraction, and knee adduction excursions. Pain relief may result from diminished muscle cocontractions rather than from so-called medial compartment unloading.

The effect of eight weeks of exercise on knee adduction moment in early knee osteoarthritis--a pilot study

OBJECTIVE

Reduced muscle function, causing greater knee joint load, is a potentially modifiable risk factor of knee osteoarthritis (OA). Exercise is an important treatment of knee OA, but the effect on joint load has not been determined. The aim of this study was to investigate the effect of exercise on knee adduction moment during one-leg rise and gait.

DESIGN

Patients below age 65 with early signs of radiographic knee OA, from a population-based cohort on OA development, were invited to participate in the study. They defined their most symptomatic knee as the index knee. Knee adduction moment during one-leg rise from a stool (48cm), and during gait was assessed using a three-dimensional motion analysis system, before and after eight weeks of supervised exercise.

RESULTS

Thirteen patients, seven women, mean age 54.5, 12/13 with Kellgren and Lawrence grade I or II, took part in the study. Peak knee adduction moment during one-leg rise was reduced by 0.08 (95% CI 0.01;0.16) Nm/kg, or 14%, for the index knee, and 0.05 (95% CI -0.04;0.14), or 8% for the opposite knee after eight weeks. The reductions in peak adduction moment during gait were smaller and not significant.

CONCLUSIONS

This study indicates that peak knee adduction moment could be reduced by supervised, individualized exercise in middle-aged patients presenting early signs of knee osteoarthritis, suggesting further investigation of this area. Peak adduction moment during one-leg rise seems to be more sensitive to deviations and change than peak adduction moment during gait in this population.

The effect of total knee replacement on dynamic support of the body during walking and stair ascent

BACKGROUND

Little is known about the effects of total knee replacement surgery on the contributions of individual joint moments to the total support moment. A better understanding of these effects may enhance rehabilitation protocols and determine factors related to long-term surgical outcome.

METHOD

Twenty-one subjects with total knee replacement and 21 controls performed level walking and stair ascent at two testing periods, pre- and 6 months post-surgery. Variables studied included gait velocity, stride length, knee flexion angle, net joint moments of the hip, knee and ankle, and total support moment. Data were analyzed at the first peak vertical ground reaction force.

FINDINGS

For level walking, the total support moment, knee extensor moment, and knee flexion angle of total knee replacement patients were less than controls at post-surgery. For stair ascent, the patient group total support moment, ankle plantarflexor moment, and knee flexion angle were less than controls at both testing periods, while knee extensor moment was less than controls at post-surgery. Extensor synergies of the total knee replacement patients revealed less knee and more hip contributions during level walking and larger hip contributions during stair ascent to the total support moment than controls at both testing periods.

INTERPRETATION

A feature of total knee replacement gait, pre- and post-surgery, is a stiff knee attitude which may serve to protect the quadriceps. The larger hip extensor contribution to the total support moment observed in the patients may compensate for the diminished knee extensor contribution during level walking and stair ascent.

BLISS index for analyzing knee osteoarthritis trials data

OBJECTIVES

Different pain thresholds were investigated, using the WOMAC Pain Scale (WOMAC-P) to determine if they could differentiate between treatment groups (hylan G-F 20 vs. appropriate care) at low and very low levels of state attainment in patients with knee osteoarthritis (OA). A method, termed the BLISS (Bellamy et al. Low Intensity Symptom State-attainment) Index, for analyzing OA knee clinical trials data, was proposed.

STUDY DESIGN AND SETTING

Five analyses were performed: time to first BLISS day, BLISS days over 12 months, patients with a BLISS response at month 12, patients with a BLISS response at any time, and number of BLISS periods over 12 months. For each analysis, five levels of WOMAC-P were examined: <or=5 normalized units (NU), <or=10, <or=15, <or=20, and <or=25 (higher=more pain).

RESULTS

More patients in the hylan G-F 20 group achieved BLISS states in all five analyses. These differences were statistically significant for all pain threshold levels except <or=5 NU.

CONCLUSION

Five methods of measuring BLISS attainment using four prespecified threshold levels of pain were able to statistically discriminate between treatment groups. This method may potentially provide an approach, to defining which patients not only improve but also achieve a good state of health, at low and very low levels of pain intensity. BLISS-10 is a therapeutically attainable very low symptom state at which clinically important, statistically significant between-group differences are detectable, and therefore may provide a benchmark against which therapeutic interventions can be assessed. However, the value to patients, of this and other low and very low intensity pain states, requires further elaboration.

Pain relief in knee osteoarthritis reduces the propensity to trip on an obstacle

The pain associated with knee osteoarthritis (OA) has been shown to lead to an increased propensity to trip on an obstacle. Pain-relieving intra-articular injections are widely utilized in the treatment of knee OA. This study examined the effects of pain-relieving intra-articular knee injections on the ability to avoid contacting a suddenly appearing obstacle in patients with knee OA. Obstacle avoidance success rates, pain, body mass index, visual acuity, contrast sensitivity, depth perception, and single-leg stance duration were evaluated in nine patients with painful osteoarthritis of the knee and 14 age-matched healthy control subjects. Obstacle avoidance success rates, pain, and single leg stance duration were tested a second time in the patients with knee OA after they received their injections, which contained a fast-acting local anesthetic to provide rapid pain relief. After receiving the pain-relieving knee injections, patients with knee OA had 48% less pain and were 31% more successful in avoiding stepping on the obstacle. However, after receiving the injection, the obstacle avoidance success rates remained 20% less than those of the healthy controls. The results of this study suggest that knee pain-relief can decrease the propensity of people with painful knee OA to trip and fall over an obstacle. However, pain-relief alone did not return the patients with knee OA in this study to a disease-free risk of tripping.

Increased joint loads during walking--a consequence of pain relief in knee osteoarthritis

Joint pain is a primary symptom in knee osteoarthritis (OA), but the effect of pain and pain relief on the knee joint mechanics of walking is not clear. In this study, the effects of local knee joint analgesia on knee joint loads during walking were studied in a group of knee osteoarthritis patients. A group of healthy subjects was included as a reference group. The joint loads were calculated from standard gait analysis data obtained with standardised walking speed (4 km/h). The gait analyses were performed before and after pain relief by intra-articular injections of 10 mL lidocaine (1%). Pre-injection measurements revealed lower joint loads in the OA group compared to the reference group. Following injections pain during walking decreased significantly and the joint loads increased in the OA group during the late single support phase to a level comparable to the reference group. Although the patients walked with less compressive knee joint forces compared to the reference group, the effects of pain relief may accelerate the degenerative changes.

Six-week high-intensity exercise program for middle-aged patients with knee osteoarthritis: a randomized controlled trial [ISRCTN20244858]

Background

Studies on exercise in knee osteoarthritis (OA) have focused on elderly subjects. Subjects in this study were middle-aged with symptomatic and definite radiographic knee osteoarthritis. The aim was to test the effects of a short-term, high-intensity exercise program on self-reported pain, function and quality of life.

Methods

Patients aged 36–65, with OA grade III (Kellgren & Lawrence) were recruited. They had been referred for radiographic examination due to knee pain and had no history of major knee injury. They were randomized to a twice weekly supervised one hour exercise intervention for six weeks, or to a non-intervention control group. Exercise was performed at ≥ 60% of maximum heart rate (HR max). The primary outcome measure was the Knee injury and Osteoarthritis Outcome Score (KOOS). Follow-up occurred at 6 weeks and 6 months.

Results

Sixty-one subjects (mean age 56 (SD 6), 51 % women, mean BMI 29.5 (SD 4.8)) were randomly assigned to intervention (n = 30) or control group (n = 31). No significant differences in the KOOS subscales assessing pain, other symptoms, or function in daily life or in sport and recreation were seen at any time point between exercisers and controls. In the exercise group, an improvement was seen at 6 weeks in the KOOS subscale quality of life compared to the control group (mean change 4.0 vs. -0.7, p = 0.05). The difference between groups was still persistent at 6 months (p = 0.02).

Conclusion

A six-week high-intensive exercise program had no effect on pain or function in middle-aged patients with moderate to severe radiographic knee OA. Some effect was seen on quality of life in the exercise group compared to the control group.

Changes in knee moments with contralateral versus ipsilateral cane usage in females with knee osteoarthritis

BACKGROUND

Conservative treatment for osteoarthritis often involves educating the patient in methods of decreasing the load transmitted through the diseased joint. The use of a cane is one such method and the correct placement of the cane with respect to an abnormal knee joint is crucial. The purpose of this study was to compare effects on knee moments of force of contralateral versus ipsilateral cane usage in female subjects with osteoarthritic knees.

METHODS

A convenience sample of 14 subjects volunteered for this study. Subjects walked over force platforms while ground reaction force and three-dimensional kinematic data were captured using a Vicon 370 System. The subjects were tested walking: (a) unaided, (b) with ipsilateral cane, and (c) with contralateral cane. Inverse dynamics were employed to calculate temporal-spatial, kinematic and kinetic variables. Dependent variables included hip and knee frontal plane and sagittal plane moments of force, walking speed, cadence and stride length. Repeated measures ANOVA assessed differences among walking conditions.

FINDINGS

Subjects walked significantly faster in the unaided gait condition owing to a higher cadence. Ipsilateral cane use resulted in significantly larger hip (versus contralateral P=0.018; versus unaided P=0.036) and knee (versus contralateral P=0.043; versus unaided P=0.030) frontal plane peak moments during gait. Contralateral cane placement was associated with the smallest peak knee abductor (P=<0.001) and flexor (P=<0.001) moments. Knee deformity (varus or valgus) did not have any significant effect on any variable possibly due to small sample size.

INTERPRETATION

The results suggest that as is the case for the hip contralateral cane placement is the most efficacious for persons with knee osteoarthritis. In fact, no cane use may be preferable to ipsilateral cane usage as the latter resulted in the highest knee moments of force, a situation which may exacerbate pain and deformity.

Osteoarthritis of the knees increases the propensity to trip on an obstacle

Tripping on an object is the most frequent cause of falls. We examined the effects of painful osteoarthritis of the knee on obstacle avoidance success rates in older adults. Obstacle avoidance success rates, pain, body mass index, visual acuity, contrast sensitivity, depth perception, and single-leg stance duration were evaluated in 17 patients with painful osteoarthritis of the knees (age range, 59.6 +/- 8.1 years) and 14 age-matched healthy control subjects (age range, 61.1 +/- 10.0 years). The patients with osteoarthritis of the knees had a 37% lower obstacle avoidance success rate, a 54% lower single-leg stance duration, and a 24% greater body mass index than the control subjects. Age, visual acuity, contrast sensitivity, and depth perception were not different between the two groups. Obstacle avoidance success rates and single-leg stance durations decreased linearly as pain increased in the patients with osteoarthritis of the knees. Obstacle avoidance success rates also decreased linearly as single-leg stance duration decreased in the patients with osteoarthritis of the knees. Osteoarthritis of the knees reduced obstacle avoidance success rates, supporting epidemiologic studies that have found osteoarthritis to be a risk factor for falls. This study showed that pain associated with osteoarthritis of the knees increased the propensity to trip on an obstacle (the greater the pain the greater the propensity to trip and fall) and underscores the importance of treating pain associated with osteoarthritis.

Aging or osteoarthritis: which is the problem?

OA is not an inevitable consequence of aging, but aging-related changes in the musculoskeletal system increase the risk of developing OA if other risk factors are also present. The joint is a functioning biomechanical unit of the neuromuscular system. Factors that contribute to the development of joint pain and loss of joint function include those associated with aging, those associated with underuse or misuse of the musculoskeletal system, and those associated directly with the development of OA. Complex interactions exist among many of these factors such as strength, balance, and proprioception, which are affected by aging, underuse, and OA. Many older adults who have joint pain and loss of function do not exhibit structural changes of OA that can be detected by standard radiography. When structural damage is present, its contribution to pain and disability is not always clear. In the absence of pharmacologic agents that can prevent the progression of structural damage in OA, management of older adults who have joint pain and loss of function should focus on improving neuromuscular function and preventing further declines.

Effectiveness of a lateral-wedge insole on knee varus torque in patients with knee osteoarthritis

OBJECTIVES

To test whether a lateral-wedged insole, inclined at 5 degrees or 10 degrees, significantly reduces knee varus torque during walking in patients with knee osteoarthritis compared with both using no insole and with wearing nonwedged control insoles of the same material and average thickness.

DESIGN

Patients with medial knee osteoarthritis were studied while they walked wearing their comfortable shoes (1) without an insole; (2) with a 5 degrees lateral wedge compared with a nonwedged, 3.175-mm (1/8-in) even-thickness control insole; and (3) with a 10 degrees lateral wedge compared with a nonwedged 6.35-mm ((1/4)-in) even-thickness control insole.

SETTING

A gait laboratory with 3-dimensional motion analysis and force platform equipment.

PARTICIPANTS

Fifteen patients with clinical and radiographic osteoarthritis of the medial compartment of 1 knee.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Peak external knee varus torques during the stance period of gait. Data regarding lower-extremity joint torques and motions were collected, and knee joint torques using the different insoles and wedges were compared by analysis of variance.

RESULTS

Although responses varied among individuals, as a group, both the 5 degrees and 10 degrees lateral-wedge insoles significantly reduced the knee varus torque during walking compared with walking with no insole and walking with nonwedged 3.175-mm and 6.35-mm control insoles. Compared with no insole, the 5 degrees wedge reduced the peak knee varus torque values by about 6% and the 10 degrees wedge reduced the peaks by about 8%. Although there were no significant differences in speed of walking between the conditions, the 10 degrees wedge and 6.35-mm control insoles were associated with varying degrees of discomfort.

CONCLUSION

Both wedge insoles are effective in reducing the varus torque during walking beyond what theoretically could be explained by a reduced walking speed or cushioning effect from the insole. These data imply that wedged insoles are biomechanically effective and should reduce loading of the medial compartment in persons with medial knee osteoarthritis. Although the effect of the 5 degrees wedge was smaller, it may be more comfortable than the 10 degrees wedge to wear inside one's own shoes.

The contribution of type of daily activity to loading across the hip and knee joints in the elderly

OBJECTIVE

In the elderly, we evaluated loading across the hip or knee joints during different daily activities.

METHODS

Elderly people drawn from the community entering an exercise study underwent a full kinetic and kinematics analysis of five different activities, standing, walking, arising from a chair, going downstairs and bending over. Inverse dynamic equations were used to compute forces and torques across the knees and hips during all of these activities.

RESULTS

132 elderly people, mean age 75, participated. Compressive forces across the knees and hips were, by far, the greatest vector forces and were highest during stair descent and, to a lesser extent, during walking. Compressive forces were lowest during standing. The highest moments were flexion and adduction moments, and these were maximal during stair descent.

CONCLUSION

Of the five activities we studied, descending stairs was associated with the highest calculated forces and torques across the knees and hips, and that may account for its tendency to cause joint symptoms and for its possible association with osteoarthritis incidence.