The effect of internal and external foot rotation on the adduction moment and lateral–medial shear force at the knee during gait

Bilateral Asymmetry in Knee and Hip Musculoskeletal Loading During Stair Ascending/Descending in Individuals with Unilateral Mild-to-Moderate Medial Knee Osteoarthritis

Most cases of unilateral knee osteoarthritis (OA) progress to bilateral OA within 10 years. Biomechanical asymmetries have been implicated in contralateral OA development; however, gait analysis alone does not consistently detect asymmetries in OA patient gait. Stair ambulation is a more demanding activity that may be more suited to reveal between-leg asymmetries in OA patients. The objective of this study was to investigate the between-leg biomechanical differences in patients with unilateral mild-to-moderate knee OA. Sixteen unilateral mild-to-moderate medial knee OA patients and 16 healthy individuals underwent kinematic and kinetic analysis of stair ascent and descent. Stair ascent produced higher loading and muscle forces in the unaffected limb compared to the OA limb, and stair descent produced lower loading on the OA limb compared to healthy subjects. These biomechanical differences were apparent in the ankle, knee, and hip joints. The implications of these findings are that OA patients rely more heavily on their unaffected sides than the affected side in stair ascent, a strategy that may be detrimental to the unaffected joint health. The reduction in affected limb loading in stair descent is thought to be related to minimizing pain.

Simulated Tibiofemoral Joint Reaction Forces for Three Previously Studied Gait Modifications in Healthy Controls

Gait modifications, such as lateral trunk lean (LTL), medial knee thrust (MKT), and toe-in gait (TIG), are frequently investigated interventions used to slow the progression of knee osteoarthritis. The Lerner knee model was developed to estimate the tibiofemoral joint reaction forces (JRF) in the medial and lateral compartments during gait. These models may be useful for estimating the effects on the JRF in the knee as a result of gait modifications. We hypothesized that all gait modifications would decrease the JRF compared to normal gait. Twenty healthy individuals volunteered for this study (26.7 ± 4.7 years, 1.75 ± 0.1 m, 73.4 ± 12.4 kg). Ten trials were collected for normal gait as well as for the three gait modifications: LTL, MKT, and TIG. The data were used to estimate the JRF in the first and second peaks for the medial and lateral compartments of the knee via opensim using the Lerner knee model. No significant difference from baseline was found for the first peak in the medial compartment. There was a decrease in JRF in the medial compartment during the loading phase of gait for TIG (6.6%) and LTL (4.9%) and an increasing JRF for MKT (2.6%). but none was statistically significant. A significant increase from baseline was found for TIG (5.8%) in the medial second peak. We found a large variation in individual responses to gait interventions, which may help explain the lack of statistically significant results. Possible factors influencing these wide ranges of responses to gait modifications include static alignment and the impacts of variation in muscle coordination strategies used, by participants, to implement gait modifications.

Frontal plane knee moment in clinical gait analysis: A systematic review on the effect of kinematic gait changes

INTRODUCTION

The frontal plane knee moment (KAM1 and KAM2) derived from non-invasive three-dimensional gait analysis is a surrogate measure for knee joint load and of great interest in clinical and research settings. Many aspects can influence this measure either unintentionally or purposely in order to reduce the knee joint load to relieve symptoms and pain. All these aspects must be known when conducting a study or interpreting gait data for clinical decision-making.

METHODS

This systematic review was registered with PROSPERO (CRD42020187038). Pubmed and Web of Science were searched for peer-reviewed, original research articles in which unshod three-dimensional gait analysis was undertaken and KAM1 and KAM2 were included as an outcome variable. Two reviewers independently screened articles for inclusion, extracted data and performed a methodological quality assessment using Downs and Black checklist.

RESULTS

In total, 42 studies were included. Based on the independent variable investigated, these studies were divided into three groups: 1) gait modifications, 2) individual characteristics and 3) idiopathic orthopedic deformities. Among others, fast walking speeds (1) were found to increase KAM1; There were no sex-related differences (2) and genu valgum (3) reduces KAM1 and KAM2.

CONCLUSION

While consistent use of terminology and reporting of KAM is required for meta-analysis, this review indicates that gait modifications (speed, trunk lean, step width), individual characteristics (body weight, age) and idiopathic orthopedic deformities (femoral or tibial torsion, genu valgum/varum) influence KAM magnitudes during walking. These factors should be considered by researchers when designing studies (especially of longitudinal design) or by clinicians when interpreting data for surgical and therapeutic decision-making.

Finding Emergent Gait Patterns May Reduce Progression of Knee Osteoarthritis in a Clinically Relevant Time Frame

A high contact force between the medial femoral condyle and the tibial plateau is the primary cause of medial compartment knee osteoarthritis (OA). A high medial contact force (MCF) during gait has been shown to be correlated to both the knee adduction moment (KAM) and knee flexion/extension moment (KFM). In this study, we used OpenSim Moco to find gait kinematics that reduced the peaks of the KAM, without increasing the peaks of the KFM, which could potentially reduce the MCF and, hence, the progression of knee OA. We used gait data from four knee OA participants. Our simulations decreased both peaks of the KAM without increasing either peak of the KFM. We found that increasing the step width was the primary mechanism, followed by simulations of all participants to reduce the frontal plane lever arm of the ground reaction force vector about the knee, in turn reducing the KAM. Importantly, each participant simulation followed different patterns of kinematic changes to achieve this reduction, which highlighted the need for participant-specific gait modifications. Moreover, we were able to simulate emerging gait patterns within 15 min, enhancing the relevance and potential for the application of developed methods in clinical settings.

The dynamic characteristics of the center of pressure for toe-out gait: implications for footwear design

Background

Toe-out gait is often used as a conservative technique to reduce knee adduction moment, which has been targeted to modify knee osteoarthritis progression. The center of pressure (COP) can not only be used to evaluate gait stability, but is also more reliable and practical than local plantar pressures as it does not depend on accurate foot zone divisions. However, to the authors’ knowledge, few study has reported the influence of the foot progression angle on the dynamic characteristics of the COP.

Research question

The aim of the study was to investigate the effects of the deliberately toe-out gait on the COP trajectory and stability during walking in healthy individuals.

Methods

Thirty healthy young adults were asked to walk along an 8-m walkway. A Footscan 1 m pressure plate was used to measure the center of pressure during walking.

Results

Compared to the normal gait, the COP of the toe-out gait shifted laterally during the initial contact phase, and shifted laterally and anteriorly during the forefoot contact phase. The mean anterior–posterior velocity of COP reduced by 0.109 m/s during the foot flat phase and the duration of the foot flat phase and forefoot push off phase increased by 4.5% and reduced by 7.0%, respectively.

Significance

Compared to the normal gait, the findings of this study suggest that biomechanical alteration of foot under our experimental conditions may decrease gait stability and increase forefoot load during toe-out walking. The situation may be improved by well-designed footwear or custom-made insole and the biomechanics analysis method can be used to test the efficacy of therapeutic footwear or insole for individuals with deliberately toe-out walking.

Graphical Abstract

Gait modification with subject-specific foot progression angle in people with moderate knee osteoarthritis: Investigation of knee adduction moment and muscle activity

BACKGROUND

Subject-specific foot progression angle (SSFPA) as a personalized gait modification is a novel approach to specifically reducing knee adduction.

OBJECTIVE

This study aimed to investigate the effect of gait modification with SSFPA on the knee adduction moment and muscle activity in people with moderate knee osteoarthritis (KOA).

METHODS

In this clinical trial, nineteen volunteers with moderate KOA were instructed to walk in four different foot progression angle conditions (5° toe-out, 10° toe-out, 5° toe-in, and 10° toe-in) to determine SSFPA that caused the greatest reduction in the greater peak of the knee adduction moment (PKAM). Immediately and after 30 minutes of gait modification with SSFPA, peak root means square (PRMS) and medial and lateral co-contraction index (CCI) were evaluated in the knee muscles.

RESULT

Walking with 10° toe-in showed the most reduction in the greater PKAM (17.52 ± 15.39%) compared to 5° toe-in (7.1 ± 19.14%), 10° toe-out (1.26 ± 23.13%), and 5° toe-out (7.64 ± 16.71%). As the immediate effect, walking with SSFPA caused a 20.71 ± 12.07% reduction in the greater PKAM than the basic FPA (p < 0.001). After 30 minutes of gait retraining, the greater PKAM decreased by 10.36 ± 26.24%, but this reduction was not significant (p = 0.17). In addition, PRMS of lateral gastrocnemius increased (p = 0.04), and lateral CCI increased 10.72% during late stance (p = 0.04).

CONCLUSION

Our findings suggest the immediate effect of gait modification with SSFPA on decreasing the knee adduction moment. After gait retraining with SSFPA, the increase of lateral muscle co-contraction may enhance lateral knee muscle co-activity to unload the medial knee compartment. Clinical Trial Register Number: IRCT20101017004952N8.

Comparative effectiveness of two methods for inducing osteoarthritis in a novel animal model, the Diannan small-ear pig

Background

Varieties of animals were used to study osteoarthritis pathogenesis. The Diannan small-ear pig, which is native to Yunnan, China, is thought to have an articular anatomy similar to that of humans and is more likely to be a source of pathological tissues than other animals. The aim of this study was to determine whether this animal can serve as a more effective osteoarthritis model and explore the role of SDF-1/CXCR4 signaling pathway in the development of Osteoarthritis in animals.

Methods

Twenty-seven adult pigs were randomly divided into three groups and underwent the Hulth procedure, papain articular injection, and conventional breeding. After 4, 8, and 12 weeks, cartilage tissues from knee joint were extracted for general and histological observation, immunofluorescence, and biochemical analysis. Synovium was taken out for stromal cell-derived factor-1 analysis.

Results

Histopathological observation showed obvious cartilage loss in two experimental groups, this cartilage loss was more severe in the chemical groups. Synovial stromal cell-derived factor1 levels increased over time in all groups. mRNA and protein levels of matrix metalloproteinase-3 were much higher in the chemical groups than in the other groups, whereas levels of collagen type II and aggrecan were significantly lower in the chemical groups than in the other groups. Immunofluorescence assays of collagen type II revealed an apparent reduction in this marker in the chemical groups compared with the other groups.

Conclusions

These results indicated that the Diannan small-ear pig can be used as an effective osteoarthritis model. In addition, it is much more convenient and much faster to induce osteoarthritis by intra-articular injection of papain, which is a method worthy of being promoted.

Effect of trunk muscles fatigue on plantar pressure distribution in novice runners

During running, trunk muscles act to sufficiently contribute to the energy generation and transmission of the body parts. Improper function of trunk muscles affects running mechanics adversely and could result in altered lower limb energetics. The aim of this study was to examine the effects of trunk muscles fatigue on plantar pressure distribution in novice runners. 46 novice heel-to-toe runners (26 female and 20 male) ran in 3.3 m/s before and after the trunk muscles fatigue along the plantar pressure measuring device. Then, participants performed trunk muscles fatigue protocol. Trunk muscles fatigue protocol consisted of four consecutive cycles of seven exercises (1) rotating trunk with a medicine ball in sitting position, 2) prone static torso extension with a medicine ball, 3) rotate lower torso with a medicine ball in supine position, 4) incline sit-ups with a weight plate, 5) lateral side binding with a weight plate, 6) rotating lumbar extension with weighted plate, and 7) standing trunk rotation with weighted pulley resistant. After trunk muscles fatigue, increases in loading of lesser toes (p = 0.001, ES = 0.379), fourth (p = 0.001, ES = 0.474) and fifth metatarsals (p = 0.004, ES = 0.173) and medial and lateral heel (p = 0.018,0.001, ES = 0.118,0.427) were observed. Also, foot progression angle (p = 0.001, ES = 392) and relative time of initial contact phase (p = 0.003, ES = 0.182) decreased. The trunk muscles fatigue could alter the plantar pressure distribution pattern. Novice runners should consider strengthening of the trunk region muscles to avoid trunk muscles strength reduction-related changes in running mechanics.

Tibiofemoral Contact Measures During Standing in Toe-In and Toe-Out Postures

Knee osteoarthritis is thought to result, in part, from excessive and unbalanced joint loading. Toe-in and toe-out gait modifications produce alterations in external knee joint moments, and some improvements in pain over the short- and long-term. The aim of this study was to probe mechanisms of altered joint loading through the assessment of tibiofemoral contact in standing with toe-in and toe-out positions using an open magnetic resonance scanner. In this study, 15 young, healthy participants underwent standing magnetic resonance imaging of one of their knees in 3 foot positions. Images were analyzed to determine contact in the tibiofemoral joint, with primary outcomes including centroid of contact and contact area for each compartment and overall. The centroid of contact shifted laterally in the lateral compartment with both toe-in and toe-out postures, compared with the neutral position (P < .01), while contact area in the medial and lateral compartments showed no statistical differences. Findings from this study indicate that changes in the loading anatomy are present in the tibiofemoral joint with toe-in and toe-out and that a small amount of lateralization of contact, especially in the lateral compartment, does occur with these altered lower limb orientations.

Effects of idiopathic flatfoot deformity on knee adduction moments during walking

INTRODUCTION

Flatfoot deformity is commonly characterized by a subtalar valgus, a low medial longitudinal arch, and abduction of the forefoot. Although flatfoot deformity has been associated with lower first (KAM1) and second (KAM2) peak knee adduction moments during walking, the biomechanical connection remains unknown.

RESEARCH QUESTION

We hypothesized that hindfoot eversion, lateral calcaneal shift correlate with KAM1 and forefoot abduction and arch height with KAM2, due to the lateralization of the ground reaction force vector resulting from shifted heel and forefoot in flatfoot deformity.

METHODS

Gait data from 103 children with flatfoot deformity who underwent three-dimensional gait analysis with the Oxford Foot Model were retrospectively included. Children with knee varus/valgus, in- and out-toeing were excluded. Fifteen healthy children with a rectus foot type were also collected from the database. Lateral calcaneal shift was defined as the distance between the projection of the ankle joint center onto the calcaneal axis and the midpoint of the calcaneal axis formed by the medial and lateral calcaneal markers. A subgroup of children with idiopathic flatfoot deformity that had received corrective surgery was also identified. Statistical analysis included Pearson's correlations and independent and paired t-tests (α < .05).

RESULTS

When compared to a norm cohort, flatfooted children had significant lower KAM1 and KAM2 (t-test, P < .001). Lateral calcaneal shift correlated with KAM1 and KAM2 (r = 0.42, p < .001 and r = 0.32, P < .001, respectively). Arch height correlated with KAM2 (r = 0.23, p = 0.017). KAM1 and KAM2 normalized after surgery and the change in KAM1 correlated with the change in lateral calcaneal shift for children who underwent corrective surgery.

SIGNIFICANCE

Lateral calcaneal shift explains the reduction of KAM1 by lateralization of the point of force application in flatfooted children. It is recommended to consider the lateral calcaneal shift when investigating KAM in gait analysis research.

Foot Rotation Gait Modifications Affect Hip and Ankle, But Not Knee, Stance Phase Joint Reaction Forces During Running

Alterations of foot rotation angles have successfully reduced external knee adduction moments during walking and running. However, reductions in knee adduction moments may not result in reductions in knee joint reaction forces. The purpose of this study was to examine the effects of internal and external foot rotation on knee, hip, and ankle joint reaction forces during running. Motion capture and force data were recorded of 19 healthy adults running at 3.35 m/s during three conditions: (1) preferred (normal) and with (2) internal and (3) external foot rotation. Musculoskeletal simulations were performed using opensim and the Rajagopal 2015 model, modified to a two degree-of-freedom knee joint. Muscle excitations were derived using static optimization, including muscle physiology parameters. Joint reaction forces (i.e., the total force acting on the joints) were computed and compared between conditions using one-way analyses of variance (ANOVAs) via statistical parametric mapping (SPM). Internal foot rotation reduced resultant hip forces (from 18% to 23% stride), while external rotation reduced resultant ankle forces (peak force at 20% stride) during the stance phase. Three-dimensional and resultant knee joint reaction forces only differed at very early and very late stance phase. The results of this study indicate, similar to previous findings, that reductions in external knee adduction moments do not mirror reductions in knee joint reaction forces.

How foot progression angle affects knee adduction moment and angular impulse in people with and without medial knee osteoarthritis: a meta-analysis

OBJECTIVE

To investigate effects of foot progression angle (FPA) modification on the first and second peaks of external knee adduction moment (EKAM) and knee adduction angular impulse (KAAI) in individuals with and without medial knee osteoarthritis (OA) during level walking.

METHODS

PubMed, Embase, CINAHL, Web of Science and SPORTDiscus were searched from inception to February 2020 by two independent reviewers. Included studies compared FPA modification (toe-in or toe-out gait) interventions to lower EKAM and/or KAAI with natural walking. Studies were required to report the first or second peaks of EKAM or KAAI.

RESULTS

Sixteen studies were included and more than 85% of included patients were graded with Kellgren-Lawrence II-IV knee OA. Toe-in gait reduced the first EKAM peak (standard mean difference (SMD): -0.75; 95%CI: -1.05~-0.45) and KAAI (SMD: -0.46; 95%CI: -0.86~-0.07), while toe-out gait reduced the second EKAM peak (SMD: -1.04; 95%CI: -1.34~-0.75) in healthy individuals. For patients with knee OA, toe-out gait reduced the second EKAM peak (SMD: -0.53; 95%CI: -0.75~-0.31) and KAAI (SMD: -0.26; 95%CI: -0.49~-0.03) while toe-in gait did not affect both EKAM peaks and KAAI.

CONCLUSION

Discrepancy in biomechanical effects of FPA modification was demonstrated between individuals with and without medial knee OA. Compared with natural walking, both toe-in and toe-out gait may be more effective in lowering EKAM and KAAI in healthy individuals. Toe-out gait may reduce EKAM and KAAI in patients with mild to severe knee OA. There is insufficient data from patients with early-stage knee OA, indicating future research is required.

Compensatory mechanisms in children with idiopathic lower extremity internal rotational malalignment during walking and running

BACKGROUND

Noticeable in-toeing gait is present in most children with internal rotational malalignment and often a reason to consult an orthopedic specialist. The risk of tripping may be higher for these patients.

RESEARCH QUESTION

The aim of this study was to determine compensatory mechanisms adopted by children with internal rotational deformities to avoid tripping and falling during walking and running.

METHODS

Sixty-nine patients between 5-18 years with idiopathic internal rotational malalignment were retrospectively included and subdivided into three groups: 18 patients with internal tibial torsion (ITT), 25 patients with internal femoral torsion (ITF) and 26 patients with both (ITB). Twenty-two typically developing age-matched children (TD) were analyzed for comparison. Three-dimensional gait data were evaluated. ANOVA's on two factors, group (ITT, ITF, ITB, TD) and movement (walking, running) with post-hoc t-tests were used to identify significant differences between groups.

RESULTS

All groups had significantly greater step width than TD during walking (P ≤ .002) and all torsional groups had significantly greater step width during running (P ≤ .001). Similarly, all torsional groups showed greater peak ankle dorsiflexion in swing during running than TD (P ≤ .006). Only the ITT group showed significantly greater external hip rotation than TD. When compared to TD, the ITF and ITB group had a significantly lower hip abduction moment in stance during running, but not for walking (P ≤ .032).

SIGNIFICANCE

Compensatory mechanisms in children with internal rotational deformities were mostly dependent on the location of rotational malalignment. All children with internal rotational malalignment had greater ankle dorsiflexion and greater step width during running. Especially in active patients, this greater ankle dorsiflexion during running may result in overuse of the ankle dorsiflexor muscles, while greater step width may have beneficial effects in normalizing knee adduction moments.

Effect of walking with a modified gait on activation patterns of the knee spanning muscles in people with medial knee osteoarthritis

OBJECTIVE

To evaluate muscle activation patterns and co-contraction around the knee in response to walking with modified gait patterns in patients with medial compartment knee-osteoarthritis (KOA).

DESIGN

40 medial KOA patients walked on an instrumented treadmill. Surface EMG activity from seven knee-spanning muscles (gastrocnemius, hamstrings, quadriceps), kinematics, and ground reaction forces were recorded. Patients received real-time visual feedback on target kinematics to modify their gait pattern towards three different gait modifications: Toe-in, Wider steps, Medial Thrust. The individualized feedback aimed to reduce their first peak knee adduction moment (KAM) by ≥10%. Changes in muscle activations and medial/lateral co-contraction index during the loading response phase (10-35% of the gait cycle) were evaluated, for the steps in which ≥10% KAM reduction was achieved.

RESULTS

Data from 30 patients were included in the analyses; i.e. all who could successfully reduce their KAM in a sufficient number of steps by ≥10%. When walking with ≥10% KAM reduction, Medial Thrust gait (KAM -31%) showed increased flexor activation (24%), co-contraction (17%) and knee flexion moment (35%). Isolated wider-step gait also reduced the KAM (-26%), but to a smaller extent, but without increasing muscle activation amplitudes and co-contraction. Toe-in gait showed the greatest reduction in the KAM (-35%), but was accompanied by an increased flexor activation of 42% and hence an increased co-contraction index.

CONCLUSION

Gait modifications that are most effective in reducing the KAM also yield an increase in co-contraction, thereby compromising at least part of the effects on net knee load.

Tibialis posterior muscle pain effects on hip, knee and ankle gait mechanics

BACKGROUND

Tibialis posterior (TP) dysfunction is a common painful complication in patients with rheumatoid arthritis (RA), which can lead to the collapse of the medial longitudinal arch. Different theories have been developed to explain the causality of tibialis posterior dysfunction. In all these theories, pain is a central factor, and yet, it is uncertain to what extent pain causes the observed biomechanical alterations in the patients. The aim of this study was to investigate the effect of experimental tibialis posterior muscle pain on gait mechanics in healthy subjects.

METHODS

Twelve healthy subjects were recruited for this randomized crossover study. Experimental pain was induced by ultrasound-guided injection of 1 mL hypertonic saline into the upper part of the right tibialis posterior muscle with the use of isotonic saline as non-pain-inducing control. Subsequently, kinematic data during three self-paced over ground walking for each condition were collected. Ground reaction forces and external moments were measured from force plates installed in the floor. Painful areas were evaluated using body charts and pain intensity scoring via a verbal numerical rating scale.

FINDINGS

Decreased hip internal rotation was observed during the pain condition at the end of the stance phase. There were no changes in gait velocity and duration of stand phase between the pain and no pain conditions. Reduced external joint moment was found for external knee rotation and for external hip rotation.

INTERPRETATION

The study has demonstrated that induced pain in the TP muscle evokes kinematic alteration in the hip and the knee joints, but not in the ankle, which suggest an underlying early stage joint compensatory mechanism. These findings suggest the need to include those joints in current physical evaluations of tibialis posterior dysfunction.

Combined effects of knee brace, laterally wedged insoles, and toe-out gait on knee adduction moment and fall risk in moderate medial knee osteoarthritis patients

BACKGROUND:

Knee osteoarthritis is a major contributor to the global burden of disease. There is a need of reducing knee joint load and to improve balance and physical function among knee osteoarthritis patients.

OBJECTIVES:

To test the hypothesis that toe-out gait will reduce second peak knee adduction moment further and increase fall risk when combined with knee brace and laterally wedged insole in knee osteoarthritis patients.

STUDY DESIGN:

Single visit study with repeated measures.

METHODS:

First and second peak knee adduction moments, fall risk and comfort level. First and second peak knee adduction moments were determined from three-dimensional gait analysis, completed under six randomized conditions: (1) natural, (2) knee brace, (3) knee brace + toe-out gait, (4) laterally wedged insole, (5) laterally wedged insole + toe-out gait, and (6) knee brace + laterally wedged insole + toe-out gait. Fall risk was assessed by Biodex Balance System using three randomized stability settings: (1) static, (2) moderate dynamic setting (FR12), and (3) high dynamic setting (FR8).

RESULTS:

The reduction in first peak knee adduction moment and second peak knee adduction moment was greatest (7.16% and 25.55%, respectively) when toe-out gait combine with knee brace and laterally wedged insole. Significant increase in fall risk was observed with knee brace + laterally wedged insole + toe-out gait (42.85%) at FR12. Similar significant balance reductions were found at FR8 condition for knee brace + toe-out gait (35.71%), laterally wedged insole + toe-out gait (28.57%), and knee brace + laterally wedged insole + toe-out gait (50%) as compared to natural. However, knee brace decreased fall risk at FR12 by 28.57%.

CONCLUSION:

There is a synergistic effect of toe-out when combined with knee brace and laterally wedged insole concurrently in second peak knee adduction moment reduction but with a greater degree of fall risk. Simultaneous use of conservative treatments also decreases comfort level.

CLINICAL RELEVANCE

Patients with mild and moderate knee osteoarthritis are usually prescribed conservative treatment techniques. This study will provide an insight whether or not a combination of these techniques have a synergistic effect in reducing knee joint load.

Return to play following anterior cruciate ligament reconstruction: incorporating fatigue into a return to play functional battery. Part A: treadmill running

Background

The risk of reinjury and other sequelae following anterior cruciate ligament reconstruction (ACLR) remains high. Lack of knowledge regarding factors contributing to these risks limits our ability to develop sensitive return to play (RTP) tests. Using a running task, we evaluate whether fatigue induces alterations in foot progression angle (FPA), a proposed biomechanical risk factor and could be used to enhance RTP test sensitivity.

Method

Transverse plane foot kinematics (FPA) were assessed for 18 post-ACLR subjects during a treadmill running task, before and after a generalised lower limb fatigue protocol. Subject’s contralateral limbs were used as a control group.

Results

A small but significant difference between FPA for ACLR and contralateral limbs was observed before but not after fatigue. When confounding variables were considered, there was a significant difference in FPA change between ACLR and contralateral limbs from the prefatigue to postfatigue state.

Conclusions

Following ACLR athletes may develop a knee-protective movement strategy that delays the progression of osteoarthritis in the ACL-injured knee. This may, however, increase the risk of ACL reinjury. Following the onset of fatigue this proposed movement strategy, and thus osteoarthritis protection, is lost.

Effects of foot progression angle adjustment on external knee adduction moment and knee adduction angular impulse during stair ascent and descent

Foot progression angle adjustment was shown to reduce external knee adduction moment (EKAM) and knee adduction angular impulse (KAAI) during level ground walking. However, evidence on effects of foot progression angle adjustment on the above surrogate measures of medial knee loading during stair climbing is limited. Hence, this study examined the effects of toe-in and toe-out gait on EKAM and KAAI during stair ascent and descent. Kinematic and kinetic data were collected from thirty-two healthy adults during stair ascent and descent with toe-in, toe-out and natural gait. A repeated measures ANOVA indicated that toe-in gait significantly reduced the first EKAM peak (P < 0.001) and KAAI (P = 0.002), while toe-out gait significantly increased the first (P < 0.001) and second (P = 0.04) EKAM peaks and KAAI (P < 0.001) when compared with natural gait during stair ascent. During stair descent, toe-in gait significantly reduced the first (P < 0.001) and second (P = 0.032) EKAM peaks and KAAI (P < 0.001), whilst toe-out gait significantly increased the first EKAM peak (P = 0.022) and KAAI (P = 0.028) when compared with natural gait. In conclusion, toe-in gait was found to be a viable strategy in reducing medial knee loading during stair climbing.

Effect of foot progression angle adjustment on the knee adduction moment and knee joint contact force in runners with and without knee osteoarthritis

BACKGROUND

Knee adduction moment (KAM) is often used as a surrogate marker of knee contact force (KCF) during walking. Previous studies have reported potential benefits to reduce KAM in patients with knee osteoarthritis (OA) by foot progression angle adjustment. However, KAM is an external moment and it does not consider any muscle contribution to the joint loading, which should pose a greater influence in running than walking.

RESEARCH QUESTION

This study used a computational model to compare KAM and KCF between runners with and without knee OA during running. In addition, we evaluated the KAM and KCF when runners adjusted to an out-toe running style.

METHODS

Kinematic, kinetic, and lower limb EMG data were collected from 9 runners with knee OA and 10 healthy counterparts. They were asked to run at their usual speed with standard shoes on an instrumented treadmill.

RESULTS

We found no significant difference in the KAM during running between OA and the healthy group (p > 0.376). However, runners with knee OA exhibited a greater total KCF than the healthy counterparts (p < 0.041). We did not observe any reduction in KAM after foot progression angle adjustment (p > 0.346). Surprisingly, an increase in the longitudinal KCF and total KCF were found with adjustment of foot progression angle (p < 0.046).

SIGNIFICANCE

Unlike the findings reported by the previous walking trials, our findings do not support the notion that foot progression angle adjustment would lead to a lower joint loading during running.

Combined effects of knee brace, laterally wedged insoles and toe-in gait on knee adduction moment and balance in moderate medial knee osteoarthritis patients

OBJECTIVE

To test the hypothesis that toe-in gait (TI) will further reduce first peak (Knee Adduction Moment) KAM and decrease balance when combined with a knee brace (KB) and laterally wedged insoles (LWI) in medial knee osteoarthritis (kOA) patients.

PARTICIPANTS

Twenty patients with bilateral symptomatic medial kOA.

INTERVENTIONS

4-point leverage-based KB, full-length LWI with 5° inclination and toe-in gait (TI).

MAIN OUTCOME MEASURES

First and second peak knee adduction moment (fKAM and sKAM respectively), balance and pain.

METHODS

The fKAM and sKAM were determined from 3-dimensional gait analysis with six randomized conditions: (1) N (without any intervention), (2) KB, (3) KB + TI, (4) LWI, (5) LWI + TI, (6) KB + LWI + TI. Balance was assessed by Biodex Balance System using three stability settings, (i) Static (ii) Moderate dynamic setting for fall risk (FR12) and (iii) High dynamic setting for fall risk (FR8).

RESULTS

The reduction in fKAM and sKAM was greatest (19.75% and 12%) when TI was combined with KB and LWI respectively. No change in balance was observed when TI combined with KB, and LWI and when used concurrently with both the orthosis at static and FR12 conditions. Significant balance reduction was found at FR8 for KB + TI (22.22%), and KB + LWI + TI (35.71%). Pain increased significantly for KB (258%), KB + TI (305%), LWI + TI (210%) and KB + LWI + TI (316%). LWI showed no effect on pain.

CONCLUSIONS

There is a synergistic effect of TI when combined with KB and LWI concurrently in sKAM reduction. However, the concurrent use of TI, KB and LWI decreases balance and pain as assessed on a highly dynamic platform.

Effects of toe-in and toe-in with wider step width on level walking knee biomechanics in varus, valgus, and neutral knee alignments

BACKGROUND

Increased peak external knee adduction moments exist for individuals with knee osteoarthritis and varus knee alignments, compared to healthy and neutrally aligned counterparts. Walking with increased toe-in or increased step width have been individually utilized to successfully reduce 1st and 2nd peak knee adduction moments, respectfully, but have not previously been combined or tested among all alignment groups. The purpose of this study was to compare toe-in only and toe-in with wider step width gait modifications in individuals with neutral, valgus, and varus alignments.

METHODS

Thirty-eight healthy participants with confirmed varus, neutral, or valgus frontal-plane knee alignment through anteroposterior radiographs, performed level walking in normal, toe-in, and toe-in with wider step width gaits. A 3×3 (group×intervention) mixed model repeated measures ANOVA compared alignment groups and gait interventions (p<0.05).

RESULTS

The 1st peak knee adduction moment was reduced in both toe-in and toe-in with wider step width compared to normal gait. The 2nd peak adduction moment was increased in toe-in compared to normal and toe-in with wider step width. The adduction impulse was also reduced in toe-in and toe-in with wider step width compared to normal gait. Peak knee flexion and external rotation moments were increased in toe-in and toe-in with wider step width compared to normal gait.

CONCLUSION

Although the toe-in with wider step width gait seems to be a viable option to reduce peak adduction moments for varus alignments, sagittal, and transverse knee loadings should be monitored when implementing this gait modification strategy.

Combined effect of toe out gait and high tibial osteotomy on knee adduction moment in patients with varus knee deformity

BACKGROUND

Gait adaptations, including toe out gait, have been proposed as treatments for knee osteoarthritis. The clinical application of toe out gait, however, is unclear. This study aims to identify the changes in Knee adduction moment in varus knee deformity assessing toe out gait as an alternative to high tibial osteotomy, and if any change in dynamic loading persists post operatively, when anatomical alignment is restored.

METHODS

Three-dimensional motion analysis was performed on 17 patients with medial compartment knee osteoarthritis and varus deformity prior to undergoing high tibial osteotomy, 13 patients were assessed post-operatively, and results compared to 13 healthy controls.

FINDINGS

Pre-operatively, there was no significant difference between natural and toe out gait for measures of knee adduction moment. Post high tibial osteotomy, first (2.70 to 1.51% BW·h) and second peak (2.28 to 1.21% BW·h) knee adduction moment were significantly reduced, as was knee adduction angular impulse (1.00 to 0.52% BW·h·s), to a healthy level. Adopting toe out gait post-operatively reduced the second peak further to a level below that of healthy controls.

INTERPRETATION

Increasing the foot progression angle from 20° (natural) to 30° in isolation did not significantly alter the knee adduction moment or angular impulse. This suggests that adopting a toe out gait, in isolation, in an already high natural foot progression angle, is not of benefit. Adopting toe out gait post-operatively, however, resulted in a further reduction in the second peak to below that of the healthy control cohort, however, this may increase lateral compartment load.

General scheme to reduce the knee adduction moment by modifying a combination of gait variables

Reducing the knee adduction moment (KAM) is a promising treatment for medial compartment knee osteoarthritis (OA). Although several gait modifications to lower the KAM have been identified, the potential to combine modifications and individual dose-responses remain unknown. This study hypothesized that: (i) there is a general scheme consisting of modifications in trunk sway, step width, walking speed, and foot progression angle that reduces the KAM; (ii) gait modifications can be combined; and (iii) dose-responses differ among individuals. Walking trials with simultaneous modifications in step width, walking speed, progression angle, and trunk sway were analyzed for 10 healthy subjects. Wider step width, slower speed, toeing-in, and increased trunk sway resulted in reduced first KAM peak, whereas wider step width, faster speed, and increased trunk sway reduced the KAM angular impulse. Individual regressions accurately modeled the amplitude of the KAM variables relative to the amplitude of the gait modification variables, while the dose-responses varied strongly among participants. In conclusion, increasing trunk sway, increasing step width, and toeing-in are three gait modifications that could be combined to reduce KAM variables related to knee OA. Results also indicated that some gait modifications reducing the KAM induced changes in the knee flexion moment possibly indicative of an increase in knee loading. Taken together with the different dose-responses among subjects, this study suggested that gait retraining programs should consider this general scheme of modifications with individualization of the modification amplitudes. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1547-1556, 2016.

The relationship between the load on the knee joint during walking and the biomechanical characteristics of single-leg standing

[Purpose] The purpose of the present study was to investigate the relationship between the external knee adduction moment (KAM) during walking and the biomechanical characteristics of single-leg standing in healthy subjects. [Subjects and Methods] Twenty-eight healthy subjects were recruited for this study. Data were collected while the subjects performed walking and single-leg standing using a motion analysis system with six digital video cameras and two force plates. Pearson’s correlation coefficient was used to quantify the relationship between peak KAM during walking and single-leg standing. To determine whether the kinematic behavior of the pelvis and trunk during single-leg standing are associated with peak KAM during walking, Pearson’s correlation coefficients were calculated and stepwise linear regression was performed. [Results] The peak KAM during single-leg standing was significantly correlated with that during walking. The peak KAM during walking was significantly correlated with the peak lateral lean of the trunk and the peak lateral tilt of the pelvis during single-leg standing. The results of stepwise linear regression analysis show the peak KAM during walking was partially explained by the peak lateral lean of the trunk during single-leg standing. [Conclusion] Our findings suggest that single-leg standing might be a useful method for predicting the peak KAM during walking.

Wedged Insoles and Gait in Patients with Knee Osteoarthritis: A Biomechanical Review

The study of gait biomechanics in individuals with knee osteoarthritis has become widespread, especially in regards to the knee adduction moment-a variable commonly believed to be associated with knee osteoarthritis progression. Unfortunately, this variable is often studied clinically without considering how it is derived, or what it means in a mechanical context. The use of footwear for knee osteoarthritis management has received much attention as well. However, in many cases, footwear is studied without regard for the mechanical effects they actually induce on the patient. Therefore, this review aims to summarize the current state of knowledge in regards to knee osteoarthritis gait and footwear biomechanics, by taking a step back to review the foundations of these two research areas. First, an overview of the calculation of the knee adduction moment is provided, along with mechanical considerations. Then, this is used to discuss current evidence for wedged insoles and highlight knowledge gaps. The intent was to place this mechanical information in a clinically-oriented framework for approachability by scientists, engineers and clinicians alike. Based on this discussion, areas for future investigation are proposed.

The Feasibility of Using Augmented Auditory Feedback From a Pressure Detecting Insole to Reduce the Knee Adduction Moment: A Proof of Concept Study

The objective of this work was to conduct a proof of concept study utilizing auditory feedback from a pressure-detecting shoe insole to shift plantar pressure medially in order to reduce the knee adduction moment (KAM). When compared with normal walking, 32 healthy subjects significantly reduced their peak KAM using feedback (p < 0.001). When compared with medial thrust gait, an established gait modification, walking with pressure-based feedback was equally effective at reducing the peak KAM, yet it successfully mitigated other potentially detrimental gait measures such as the peak knee flexion moment (KFM), knee internal rotation moment (KIrM), and a reduction in speed.

Relationships among foot position, lower limb alignment, and knee adduction moment in patients with degenerative knee osteoarthritis

[Purpose] The aim of this study was to determine the relationships among the foot progression angle, foot rotation angle, lower limb alignment, and knee adduction moments in patients with degenerative knee osteoarthritis (OA). [Subjects] Forty-eight patients diagnosed with degenerative knee OA (Kellgren-Lawrence grades 2 and 3) were included. [Methods] To assess the lower extremity alignment and weight-bearing ratio, static radiographic measurement was used. Foot progression angle, foot rotation angle, and knee adduction moments were measured by using a three-dimensional motion analysis system. [Results] The results of this study were as follows: the foot progression angle in the early and late stance phase was significantly correlated with the first and second peak knee adduction moments; the weight-bearing ratio was significantly correlated with the first and second peak knee adduction moments; and the tibiofemoral angle was significantly correlated with the first and second peak knee adduction moments. [Conclusion] The results of the present study indicated that as the foot progression angle and the foot lateral rotation angle increased, the knee adduction moment decreased. The weight-bearing ratio and tibiofemoral angle assessment with mechanical axis alignment were correlated with the knee adduction moments. These parameters may be helpful for selecting therapeutic options for patients with degenerative knee OA.

Femorotibial relationship changes as the posture changes from patellae-forward stance to preferred toe-out stance

BACKGROUND

Full-length standing anteroposterior radiograph is a standard protocol to evaluate the lower limb alignment in frontal plane. However, most people tend to stand or walk with feet pointing outward. The purpose of this study is to assess the femorotibial relationship as the posture changes from patellae-forward stance for the conventional technique of a full-length standing anteroposterior radiograph to a toe-out quiet stance using a fluoroscope.

METHODS

Femoral and tibial rotation and femorotibial rotation were measured in 60 healthy lower limbs using fluoroscopy during postural change from patellae-forward stance to toe-out quiet stance.

RESULTS

The average toe-out angle was 21.4°. The average femoral, tibial, and femorotibial rotations during postural change were 6.1°, 4.0°, and 2.1°, respectively (p = 0.000). The correlation coefficient for femoral and tibial rotation was 0.747 (p = 0.000). The correlation coefficient for femoral and femorotibial rotation was 0.670 (p = 0.000), and for tibial and femorotibial rotation was 0.006 (p = 0.962). The correlation between toe-out angle and femorotibial rotation was statistically significant (r (2) = 0.096, p = 0.016). The correlations between toe-out angle and femoral rotation, and between toe-out angle and tibial rotation were not statistically significant (r (2) = 0.047, p = 0.095, and r (2) = 0.000, p = 0.9, respectively).

CONCLUSIONS

The subject's posture significantly affects the femorotibial relationship. When a subject changes posture from a patellae-forward stance to a toe-out quiet stance, the femur rotates internally on the tibia.

LEVEL OF EVIDENCE

Diagnostic, level II.

Real-time visual feedback for gait retraining: toward application in knee osteoarthritis

Real-time visual feedback might be effective for gait retraining in patients with knee osteoarthritis, to potentially relieve symptoms and postpone knee replacement. In this study, we investigated the effect of various types of real-time visual feedback on a kinetic and a kinematic gait parameter and the different kinematic strategies adopted to reduce knee load. Seventeen healthy subjects walked on an instrumented treadmill while receiving real-time visual kinetic feedback aimed at minimizing the external knee adduction moment (KAdM, reflecting the knee load) or kinematic feedback on the hip internal rotation angle (HIR, a gait modification to reduce the KAdM). Four types of visual feedback (bar, polar plot, color change, graph) were provided. The KAdM decreased by 50 % with kinetic feedback, while kinematic feedback resulted in an HIR increase of 8° but no decrease in KAdM. The degree of change was not influenced by the type of visual feedback. The kinematic changes that reduced KAdM were increased toe-in, increased step width, and decreased hip adduction. Real-time visual feedback can effectively modify gait parameters. Feedback of the KAdM may be more effective in reducing the KAdM than controlling a kinematic parameter that is assumed to unload the knee.

Knee moment and shear force are correlated with femoral tunnel orientation after single-bundle anterior cruciate ligament reconstruction

BACKGROUND

Increasing evidence has shown that anatomic single-bundle anterior cruciate ligament reconstruction (ACLR) better restores normal knee kinematics and functionality than nonanatomic ACLR. Whether anatomic reconstruction results in better knee kinetics during daily activities has not been fully investigated.

PURPOSE

To assess the relationship between femoral tunnel angle and kinetic parameters of the knee joint during walking after single-bundle ACLR and to compare the radiographic and kinetic results of patients who underwent anatomic ACLR with those of patients who underwent nonanatomic ACLR.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-one patients who underwent unilateral ACLR were recruited, and 20 healthy subjects from a previous study were used as a control group. All surgical procedures were performed by a single surgeon, 11 using the transtibial (TT) technique and 10 using the anteromedial portal (AMP) technique. Femoral tunnel orientation was measured from posterior-to-anterior radiographs. Dynamic knee joint moments and shear forces during gait were evaluated using 3-dimensional motion analysis and inverse dynamics. Relationships between femoral tunnel angles and kinetic results were evaluated via linear regression. Results were compared between 2 ACLR groups and controls using 1-way analysis of variance.

RESULTS

Femoral tunnel angle had significant correlations with peak external knee flexion moment and posterior shear force during early stance. The TT group had a significantly smaller (more vertical) mean femoral tunnel angle (19.4° ± 4.1°) than the AMP group (36.4° ± 5.8°). Significant reductions were found in the normalized peak external knee flexion moment (TT, 0.15 ± 0.12 Nm/kg·m; AMP, 0.25 ± 0.12 Nm/kg·m; control, 0.25 ± 0.16 Nm/kg·m) (P = .032) and posterior shear force (TT, 0.64 ± 0.55 N/kg; AMP, 1.10 ± 0.58 N/kg; control, 1.35 ± 0.55 N/kg) (P = .024) in the TT group compared with controls, but not in the AMP group. Moreover, a significantly greater medial shear force was found in the TT group during the late stance phase (TT, 1.08 ± 0.32 N/kg; AMP, 0.89 ± 0.26 N/kg; control, 0.83 ± 0.22 N/kg) (P = .038). A greater peak external knee adduction moment was found in both ACL groups during the early stance phase (TT, 0.25 ± 0.07 Nm/kg·m; AMP, 0.25 ± 0.07 Nm/kg·m; control, 0.19 ± 0.05 Nm/kg·m) (P < .01).

CONCLUSION

Knee joint kinetic changes are seen within months (~10 months) after ACLR. This study revealed significant relationships between femoral tunnel orientation and postoperative knee joint flexion moment and posterior shear force during walking. The AMP technique provides better restoration of these knee kinetic parameters compared with the TT technique at this postoperative time point.

CLINICAL RELEVANCE

The femoral tunnel angle measured from plain radiographs can be used as an important metric of postoperative knee joint kinetics. This information provides a better understanding of the knee joint's biomechanical environment after ACLR using commonly used single-bundle techniques.

Individual selection of gait retraining strategies is essential to optimally reduce medial knee load during gait

BACKGROUND

The progression of medial knee osteoarthritis seems closely related to a high external knee adduction moment, which could be reduced through gait retraining. We aimed to determine the retraining strategy that reduces this knee moment most effective during gait, and to determine if the same strategy is the most effective for everyone.

METHODS

Thirty-seven healthy participants underwent 3D gait analysis. After normal walking was recorded, participants received verbal instructions on four gait strategies (Trunk Lean, Medial Thrust, Reduced Vertical Acceleration, Toe Out). Knee adduction moment and strategy-specific kinematics were calculated for all conditions.

FINDINGS

The overall knee adduction moment peak was reduced by Medial Thrust (-0.08Nm/Bw·Ht) and Trunk Lean (-0.07Nm/Bw·Ht), while impulse was reduced by 0.03Nms/Bw·Ht in both conditions. Toeing out reduced late stance peak and impulse significantly but overall peak was not affected. Reducing vertical acceleration at initial contact did not reduce the overall peak. Strategy-specific kinematics (trunk lean angle, knee adduction angle, first peak of the vertical ground reaction force, foot progression angle) showed that multiple parameters were affected by all conditions. Medial Thrust was the most effective strategy in 43% of the participants, while Trunk Lean reduced external knee adduction moment most in 49%. With similar kinematics, the reduction of the knee adduction moment peak and impulse was significantly different between these groups.

INTERPRETATION

Although Trunk Lean and Medial Thrust reduced the external knee adduction moment overall, individual selection of gait retraining strategy seems vital to optimally reduce dynamic knee load during gait.

Effects of a 10-week toe-out gait modification intervention in people with medial knee osteoarthritis: a pilot, feasibility study

OBJECTIVE

To examine the feasibility of a 10-week gait modification program in people with medial tibiofemoral knee osteoarthritis (OA), and to assess changes in clinical and biomechanical outcomes.

DESIGN

Fifteen people with medial knee OA completed 10 weeks of gait modification focusing on increasing toe-out angle during stance 10° compared to their self-selected angle measured at baseline. In addition to adherence and performance difficulty outcomes, knee joint symptoms (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and total score, numerical rating scale (NRS) of pain), and knee joint loading during gait (late stance peak knee adduction moment (KAM)) were assessed.

RESULTS

Participants were able to perform the toe-out gait modification program with minimal to moderate difficulty, and exhibited significant increases in self-selected toe-out angle during walking (P < 0.001). Joint discomfort was reported by five participants (33%) in the hip or knee joints, though none lasted longer than 2 weeks. Participants reported statistically significant reductions in WOMAC pain (P = 0.02), NRS pain (P < 0.001), WOMAC total score (P = 0.02), and late stance KAM (P = 0.04).

CONCLUSIONS

These preliminary findings suggest that toe-out gait modification is feasible in people with medial compartment knee OA. Preliminary changes in clinical and biomechanical outcomes provide the impetus for conducting larger scale studies of gait modification in people with knee OA to confirm these findings.

Biomechanical mechanisms of toe-out gait performance in people with and without knee osteoarthritis

BACKGROUND

Toe-out gait modification (increased toe-out angle) has been proposed to decrease medial knee joint loading and slow disease progression in patients with knee osteoarthritis. However, the manner in which toe-out gait modification is performed is unknown. The purposes of this study were to assess the biomechanical strategies of achieving a toe-out gait, and to compare these strategies between older individuals with knee osteoarthritis and young, healthy individuals.

METHODS

Lower limb biomechanics were evaluated for ten patients with knee osteoarthritis and for ten young, healthy individuals during treadmill walking. Two trials, consisting of natural gait followed by a ten degree increase in toe-out angle were performed. Transverse plane rotations of the thigh, shank and foot segments were calculated and compared between walking conditions and groups.

FINDINGS

External rotation changes with toe-out were significantly different between the thigh and shank, and thigh and foot (P<0.001), but not between the shank and foot (P=0.48). External rotation at each segment was not significantly different (P>0.05) between groups, with the exception of thigh rotation during natural gait (P=0.04).

INTERPRETATION

Current findings suggest that increased toe-out gait is primarily achieved through rotation of the shank and foot, with less contribution from the thigh, and those individuals with knee osteoarthritis perform a toe-out gait biomechanically similar to young, healthy individuals. Gait modification programs should address individuals' limitations, such as joint stiffness, to ensure functional performance of toe-out gait modification.

Effect of BMI on Knee Joint Torques in Ergometer Rowing

Although an authoritative panel recommended the use of ergometer rowing as a non-weight-bearing form of exercise for obese adults, the biomechanical characterization of ergometer rowing is strikingly absent. We examined the interaction between body mass index (BMI) relative to the lower extremity biomechanics during rowing in 10 normal weight (BMI 18–25), 10 overweight (BMI 25–30 kg·m−2), and 10 obese (BMI > 30 kg·m−2) participants. The results showed that BMI affects joint kinematics and primarily knee joint kinetics. The data revealed that high BMI leads to unfavorable knee joint torques, implying increased loads of the medial compartment in the knee joint that could be avoided by allowing more variable foot positioning on future designs of rowing ergometers.

A biomechanical perspective on physical therapy management of knee osteoarthritis

SYNOPSIS

Altered knee joint biomechanics and excessive joint loading have long been considered as important contributors to the development and progression of knee osteoarthritis. Therefore, a better understanding of how various treatment options influence the loading environment of the knee joint could have practical implications for devising more effective physical therapy management strategies. The aim of this clinical commentary was to review the pertinent biomechanical evidence supporting the use of treatment options intended to provide protection against excessive joint loading while offering symptomatic relief and functional improvements for better long-term management of patients with knee osteoarthritis. The biomechanical and clinical evidence regarding the effectiveness of knee joint offloading strategies, including contralateral cane use, laterally wedged shoe insoles, variable-stiffness shoes, valgus knee bracing, and gait-modification strategies, within the context of effective disease management is discussed. In addition, the potential role of therapeutic exercise and neuromuscular training to improve the mechanical environment of the knee joint is considered. Management strategies for treatment of joint instability and patellofemoral compartment disease are also mentioned. Based on the evidence presented as part of this clinical commentary, it is argued that special considerations for the role of knee joint biomechanics and excessive joint loading are necessary in designing effective short- and long-term management strategies for treatment of patients with knee osteoarthritis.

LEVEL OF EVIDENCE

Therapy, level 5.

Altering foot progression angle in people with medial knee osteoarthritis: the effects of varying toe-in and toe-out angles are mediated by pain and malalignment

OBJECTIVES

To evaluate if altering the foot progression angle (FPA) by varying magnitudes during gait alters the external knee adduction moment (KAM), knee flexion moment (KFM), knee extension moment (KEM) and/or symptoms in people with medial knee osteoarthritis (OA). Potential influence of pain and knee malalignment on load-modifying effects of FPA was investigated.

DESIGN

Participants (n = 22) underwent 3-dimensional gait analysis to measure KAM peaks, KAM impulse, KFM and KEM peaks. Following natural gait, five altered FPA conditions were performed in random order (10° toe-in, 0° FPA, 10° toe-out, 20° toe-out and 30° toe-out). A projection screen displayed their real-time FPA. Pain/discomfort at knees and feet/ankles were evaluated for each condition. Linear mixed models were used for statistical analysis.

RESULTS

Toe-in reduced the early stance peak KAM and KEM but increased the KAM impulse, late stance peak and KFM. Toe-out reduced the KAM impulse, late stance peak and KFM (P < 0.001) but increased the early stance peak KAM and KEM. All effects were greater in participants with more varus knees. Pain significantly mediated the effect of altered FPA on the KAM impulse and late stance peak. In more painful individuals, toe-in was predicted to reduce the KAM impulse and late stance peak, and increase them for toe-out gait. There were no immediate symptomatic changes.

CONCLUSIONS

Effects of altered FPA vary across all medial knee load parameters and it is difficult to determine an optimal direction of FPA change. Future studies should consider Western Ontario McMaster Universities OA Index (WOMAC) pain to judge the likely effects of altered FPA.

Effect of specific gait modifications on medial knee loading, metabolic cost and perception of task difficulty

BACKGROUND

The metabolic cost and cognitive demand of altering natural gait have not been well studied. The purpose of this investigation was to assess three modified patterns - toe out, ipsilateral trunk lean and a medial weight shift at the foot - on the basis of 1) medial knee joint load reduction, 2) metabolic cost of performance and 3) subject perception of task difficulty.

METHODS

12 healthy individuals underwent 3 dimensional motion analysis and metabolic testing to assess the gait mechanics and energy expenditure of natural gait and the three experimental gait patterns, performed to a self-selected moderate degree. Walking speed was controlled. Perceived workload was assessed using the NASA Task Load Index.

FINDINGS

Trunk lean significantly reduced first peak knee adduction moment (↓32%, P<0.001) as well as KAM impulse (↓35%, P<0.001), but was costly in terms of energy expenditure (↑11%, P<0.001) and perceived workload (↑1178%, P<0.001). A moderate toe-out pattern significantly reduced the second peak knee adduction moment (↓32%, P<0.001) and KAM impulse (↓14%, P=0.026), but had no effect on the first peak. Conversely, toe-out was least demanding in terms of additional energy expenditure (↑2%, P=0.001) and perceived workload (↑314%, P=0.001). Medial shift did not reduce knee adduction moment.

INTERPRETATION

The prioritization of joint load reduction versus additional metabolic and cognitive demands could play a substantial role in the clinical decision making process of selecting a modified gait pattern.

The Effect of Foot Progression Angle on Knee Joint Compression Force During Walking

It is unclear how rotations of the lower limb affect the knee joint compression forces during walking. Increases in the frontal plane knee moment have been reported when walking with internally rotated feet and a decrease when walking with externally rotated feet. The aim of this study was to investigate the knee joint compressive forces during walking with internal, external and normal foot rotation and to determine if the frontal plane knee joint moment is an adequate surrogate for the compression forces in the medial and lateral knee joint compartments under such gait modifications. Ten healthy males walked at a fixed speed of 4.5 km/h under three conditions: Normal walking, internally rotated and externally rotated. All gait trials were recorded by six infrared cameras. Net joint moments were calculated by 3D inverse dynamics. The results revealed that the medial knee joint compartment compression force increased during external foot rotation and the lateral knee joint compartment compression force increased during internal foot rotation. The increases in joint loads may be a result of increased knee flexion angles. Further, these data suggest that the frontal plane knee joint moment is not a valid surrogate measure for knee joint compression forces but rather indicates the medial-to-lateral load distribution.

The effects of transverse rotation angle on compression and effective lever arm of prosthetic feet during simulated stance

BACKGROUND AND AIM

Unlike sagittal plane prosthesis alignment, few studies have observed the effects of transverse plane alignment on gait and prosthesis behaviour. Changes in transverse plane rotation angle will rotate the points of loading on the prosthesis during stance and may alter its mechanical behaviour. This study observed the effects of increasing the external transverse plane rotation angle, or toe-out, on foot compression and effective lever arm of three commonly prescribed prosthetic feet.

TECHNIQUE

The roll-over shape of a SACH, Flex and single-axis foot was measured at four external rotation angle conditions (0°, 5°, 7° and 12° relative to neutral). Differences in foot compression between conditions were measured as average distance between roll-over shapes.

DISCUSSION

Increasing the transverse plane rotation angle did not affect foot compression. However, it did affect the effective lever arm, which was maximized with the 5° condition, although differences between conditions were small.

CLINICAL RELEVANCE

Increasing the transverse plane rotation angle of prosthetic feet by up to 12° beyond neutral has minimal effects on their mechanical behaviour in the plane of walking progression during weight-bearing.

Effect of the lower limb rotational alignment on tibiofemoral contact pressure

PURPOSE

The effect of the rotational alignment of lower extremities on the tibiofemoral contact mechanics is not known. This study was designed to measure the contact area and pressure within medial and lateral tibiofemoral compartments following controlled serial rotational deformities through femoral and tibial shafts.

METHODS

Eight lower extremities of fresh frozen cadavers were used. Computed tomography was conducted to measure the rotational profile of the lower extremities. Through a medial parapatellar arthrotomy, pressure sensors were implanted into both tibiofemoral compartments. Femoral and tibial mid-shaft osteotomies were performed and stabilized by non-locked intramedullary nails and external fixators in neutral rotation. The contact area and pressure were measured under axial loading in neutral rotation and following serial malrotations from 40° external to 40° internal malrotation in 10° increments.

RESULTS

Contact area was not affected by malrotations. Medial compartment contact pressure rose with external and decreased with internal malrotations whether femoral or tibial (P < 0.0001) while lateral pressure was not affected. When correlated with the cadavers' original rotational profile, decreased femoral neck anteversion was associated with increased medial pressure up to 28.5% at 20° of retroversion while it decreased with increased anteversion. On the other hand, decreased tibial torsion angle was associated with decreased medial pressure up to -32% at 10° of internal torsion and it increased with excessive external torsion. Furthermore, there was a strong positive correlation with the total rotational alignment as measured by the neck malleolar angle.

CONCLUSION

A significant interaction could be detected between the rotational alignment of the lower extremity and medial tibiofemoral compartment contact pressures.

Forces and moments on the knee during kneeling and squatting

Euler angle decomposition and inverse dynamics were used to determine the knee angles and net forces and moments applied to the tibia during kneeling and squatting with and without kneepads for 10 subjects in four postures: squatting (Squat), kneeling on the right knee (One Knee), bilateral kneeling near full flexion (Near Full) and bilateral kneeling near 90° flexion (Near 90). Kneepads affected the knee flexion (p = .002), medial forces (p = .035), and internal rotation moments (p = .006). Squat created loading conditions that had higher varus (p < .001) and resultant moments (p = .027) than kneeling. One Knee resulted in the highest force magnitudes and net moments (p < .001) of the kneeling postures. Thigh-calf and heel-gluteus contact forces decreased the flexion moment on average by 48% during Squat and Near Full.

Training multi-parameter gaits to reduce the knee adduction moment with data-driven models and haptic feedback

The purpose of this study was to evaluate gait retraining for reducing the knee adduction moment. Our primary objective was to determine whether subject-specific altered gaits aimed at reducing the knee adduction moment by 30% or more could be identified and adopted in a single session through haptic (touch) feedback training on multiple kinematic gait parameters. Nine healthy subjects performed gait retraining, in which data-driven models specific to each subject were determined through experimental trials and were used to train novel gaits involving a combination of kinematic changes to the tibia angle, foot progression and trunk sway angles. Wearable haptic devices were used on the back, knee and foot for real-time feedback. All subjects were able to adopt altered gaits requiring simultaneous changes to multiple kinematic parameters and reduced their knee adduction moments by 29-48%. Analysis of single parameter gait training showed that moving the knee medially by increasing tibia angle, increasing trunk sway and toeing in all reduced the first peak of the knee adduction moment with tibia angle changes having the most dramatic effect. These results suggest that individualized data-driven gait retraining may be a viable option for reducing the knee adduction moment as a treatment method for early-stage knee osteoarthritis patients with sufficient sensation, endurance and motor learning capabilities.