Total Support Moment Research Articles

Redistribution Of Inter-joint Sharing Of The Total Support Moment During Uphill Walking In ACL Deficiency

Redistribution Of Inter-joint Sharing Of The Total Support Moment During Uphill Walking In ACL Deficiency

Comparing Sagittal-Plane Biomechanics of Drop Jump Landing in Athletes With and Without Knee Osteoarthritis 2-Year Post-Anterior Cruciate Ligament Reconstruction.

The study aimed to determine differences in sagittal-plane joint biomechanics between athletes with and without knee osteoarthritis (OA) during drop vertical jump 2years after anterior cruciate ligament reconstruction (ACLR). Forty-one athletes with ACLR completed motion analysis testing during drop vertical jump from 30cm. Sagittal-plane peak joint angles and moments and joint contributions to total support moment (TSM) were calculated during first landing. Medial compartment knee OA of the reconstructed knee was evaluated using Kellgren-Lawrencescores (ACLR group: Kellgren-Lawrence <2; ACLR-OA group: Kellgren-Lawrence ≥2). The ACLR-OA group (n = 13) had higher hip and lower knee contributions in the surgical limb than the ACLR group and their nonsurgical limb. Further, the ACLR-OA group had higher peak hip extension moment than the ACLR group (P = .024). The ACLR-OA group had significantly lower peak knee extension and ankle plantar flexion moments and TSM (P ≤ .032) than ACLR group. The ACLR-OA group landed with increased hip extension moment, decreased knee extension and ankle plantar flexion moments and TSM, and decreased knee and increased hip contributions to TSM compared with ACLR group. The ACLR-OA group may have adopted movement patterns to decrease knee load and compensated by shifting the load to the hip. Clinicians may incorporate tailored rehabilitation programs that mitigate the decreased knee load to minimize the risk of knee OA after ACLR.

Joint contributions to sagittal plane total support moment in patients with knee osteoarthritis after anterior cruciate ligament reconstruction

BackgroundPatients with anterior cruciate ligament reconstruction (ACLR) demonstrate lower knee loading. This study aimed to determine whether sagittal plane TSM and joint contributions to total support moment (TSM) in the surgical limb are different between athletes who did and did not show radiological features of knee OA at 2 years after ACLR during triple hops (TH), single hop (TH), single-legged vertical jump (VJ), and walking. MethodsForty-one athletes with 2 years of unilateral ACLR surgery participated in this cross-sectional study. Athletes completed motion analysis testing of single-legged TH, SH, VJ, and walking tasks. Sagittal plane TSM and individual joint (ankle, knee, and hip) contributions to TSM were computed at peak knee flexion angle (TSM-PKF). Posterior-anterior radiographs were completed in standing and 30° knee flexion. Kellgren-Lawrence (KL) system was used to identify radiological features of knee OA in the medial compartment of the reconstructed knee (OA-group: KL ≥2; Non-OA group: KL<2). ResultsThere was a significant group-by-joint-by-task interaction for joint contributions to TSM-PKF (p = 0.012), with the OA-group (n = 13) had lower knee and higher hip contributions compared to the non-OA group during TH, SH, and VJ (p ≤ 0.049). There was a significant joint-by-group interaction for the joint contributions to TSM-PKF (p = 0.004), with the OA-group having lower knee (p = 0.003) and higher hip (p = 0.001) contributions compared to the Non-OA group. SignificanceThe OA-group exhibited lower knee and higher hip contributions to the sagittal plane TSM compared to the Non-OA group during the landing phase of single-limb high-demand activities. The OA-group exhibited decreased knee loading and compensated by shifting the mechanical load to the hip joint within the reconstructed knee. Decreased knee loading in the OA-group may have affected the required mechanical loading to maintain knee metabolism and integrity.

Injury and performance related biomechanical differences between recreational and collegiate runners.

Running related injuries (RRI) are common, but factors contributing to running performance and RRIs are not commonly compared between different types of runners. We compared running biomechanics previously linked to RRIs and performance between 27 recreational and 35 collegiate runners. Participants completed 5 overground running trials with their dominant limb striking a force plate, while outfitted with standardised footwear and 3-dimensional motion capture markers. Post hoc comparisons revealed recreational runners had a larger vertical loading rate (194.5 vs. 111.5 BW/s, p < 0.001) and shank angle (6.80 vs. 2.09, p < 0.001) compared with the collegiate runners who demonstrated greater vertical impulse (0.349 vs. 0.233 BWs, p < 0.001), negative impulse (-0.022 vs. -0.013 BWs, p < 0.001), positive impulse (0.024 vs. 0.014 BWs, p < 0.001), and propulsive force (0.390 vs. 0.333 BW, p = 0.002). Adjusted for speed, collegiate runners demonstrated greater total support moment (TSM), plantar flexor moment, knee extensor moment, hip extensor moment, and had greater proportional plantar flexor moment contribution and less knee extensor moment contribution to the TSM compared with recreational runners. Unadjusted for speed, collegiate runners compared with recreational had greater TSM and plantar flexor moment but similar joint contributions to the TSM. Greater ankle joint contribution may be more efficient and allow for greater capacity to increase speed. Improving plantarflexor function during running provides a strategy to improve running speed among recreational runners. Moreover, differences in joint kinetics and ground reaction force characteristics suggests that recreational and collegiate runners may experience different types of RRI.

Lower Extremity Support Moment and Distribution of Joint Moments during Sloped Running

The existing literature often exhibits inconsistent findings regarding lower extremity kinetics during sloped running, likely due to high variability of typical individual joint moments between and within runners. A better understanding of the kinetic effects of sloped running may be achieved by comparing the support moment and joint contributions among level, upslope, and downslope running. Twenty recreational runners (10 females) ran on three different conditions (level, 6° upslope and 6° downslope). Total support moment and joint contributions of the hip, knee, and ankle joints were compared among the three slope conditions using a one-way ANOVA with repeated measures and post-hoc pairwise comparisons. Our results showed that peak total support moment was highest during upslope running and was lowest during downslope running. The joint contribution to total support moment was similar in upslope and level running where the ankle joint has highest contribution followed by the knee and hip joints. During downslope running, highest knee joint contribution but least ankle and hip joint contributions were found when compared to level and upslope running.

Ambulatory support moment contribution patterns and MRI-detected tibiofemoral and patellofemoral disease worsening in adults with kneeosteoarthritis: A preliminary study.

We investigated whether baseline sagittal-plane ankle, knee, and hip contribution to the total support moment (TSM) are each associated with baseline-to-2-year tibiofemoral and patellofemoral tissue damage worsening in adults with knee osteoarthritis. Ambulatory lower-limb kinetics were captured and computed. TSM is the sum of ankle, knee, and hip extensor moments at each instant during gait. Ankle, knee, and hip contributions to TSM were computed as joint moments divided by TSM, expressed as percentages. Participants underwent MRI of both knees at baseline and 2years later. Logistic regression models assessed associations of baseline ankle contribution to TSM with baseline-to-2-year cartilage damage and bone marrow lesion worsening, adjusted for age, sex, BMI, gait speed, disease severity, and pain. We used similar analytic approaches for knee and hip contributions to TSM. Sample included 391 knees from 204 persons (age[SD]: 64[10]years; 76.5% women). Greater ankle contribution may be associated with increased odds of tibiofemoral cartilage damage worsening (OR = 2.38; 95% CI: 1.02-5.57) and decreased odds of patellofemoral bone marrow lesion worsening (OR = 0.14; 95% CI: 0.03-0.73). The ORs for greater knee contribution were in the protective range for tibiofemoral compartment and in the deleterious range for patellofemoral. Greater hip contribution may be associated with increased odds of tibiofemoral worsening (OR = 2.71; 95% CI: 1.17-6.30). Greater ankle contribution to TSM may be associated with baseline-to-2-year tibiofemoral worsening, but patellofemoral tissue preservation. Conversely, greater knee contribution may be associated with patellofemoral worsening, but tibiofemoral preservation. Preliminary findings illustrate potential challenges in developing biomechanical interventions beneficial to both tibiofemoral and patellofemoral compartments.

Total Support Moment Analysis Of The Stop-jump Task In Individuals Following Anterior Cruciate Ligament Reconstruction

Purpose: To examine total support moment in the sagittal plane and individual contribution from each joint during a dynamic sport task to understand the presence of compensatory strategies in a cohort of individuals who have undergone anterior cruciate ligament reconstruction (ACLR) and have been cleared for return-to-sport (RTS) Methods: Twenty-six individuals with unilateral ACLR and RTS clearance participated in the study (20.9 ± 6.6 years; 10.0 ± 1.7 months since surgery). Each participant completed a single-leg and double-leg stop jump task. These tasks were assessed using force plates and a 3D motion analysis system. Bilateral internal hip flexor/extensor, knee flexor/extensor, and ankle plantarflexor/dorsiflexor moments were calculated at peak vertical ground reaction force. The total support moment was calculated by summing these moments for each leg and the individual percent contribution was calculated. Paired t-tests were used to assess between-limb differences for each stop jump task in the following variables of interest: total support moment; hip, knee and ankle joint contributions to the total support moment; hip, knee and ankle moments; and peak vertical ground reaction force. Wilcoxon Signed Rank tests were used to compare variables that were not normally distributed. Statistical significance was set a priori at <0.05. Results: Internal knee extensor moment was lower in the involved limb compared to the uninvolved for both tasks (17.6%, P = 0.022; 18.4%, P = 0.008). The involved limb exhibited 18.2% decrease in knee joint contribution (P = 0.01) and 21.6% increase in ankle joint contribution (P = 0.016) to the total support moment compared to the uninvolved limb in the single-leg stop jump task. No significant between-limb differences were found for the total support moment. Conclusion: Following clearance for RTS, altered knee loading is still observed. These results suggest that compensation for the involved knee is likely due to redistribution of load to the knee of the uninvolved limb or to adjacent joints of the involved limb. A partial shift in joint contribution from the knee to the ankle during the single-leg stop jump task demonstrates intralimb compensation. Further studies are needed to investigate how these adaptations impact the prevalence of subsequent injury and poor joint health.

The center of pressure position in combination with ankle dorsiflexion and trunk flexion is useful in predicting the contribution of the knee extensor moment during double-leg squatting

BackgroundSquatting exercises are commonly used in rehabilitation for knee joint disorders; in these exercises, control of knee extensor moment is important to enhance training effects and to avoid adverse effects. Ankle dorsiflexion and trunk flexion are widely used to reduce knee extensor moments during squatting, but the increased load on the low back is a concern. The purpose of this study was to determine whether the anterior–posterior (AP) center-of-pressure (COP) position and the AP-COP position in combination with ankle dorsiflexion and trunk flexion angles can predict the contribution of the knee extensor moment during double-leg squatting.MethodsTwenty-eight healthy individuals (14 female and 14 male participants, age 22.8 ± 1.3 years) performed three sets of five consecutive double-leg squats. Kinematics and kinetics were analyzed using a three-dimensional motion analysis system with force plates. Univariate and multivariate regression analyses were performed to predict the contribution of the knee extensor moment (% total support moment) from AP-COP position, ankle dorsiflexion, and trunk flexion.ResultsThe AP-COP position was a significant predictor of the knee extensor moment contribution (R2 = 0.168, P = 0.030). Multivariate analysis showed that the ankle dorsiflexion angle (ΔR2 = 0.561, β = 0.842) and AP-COP position (ΔR2 = 0.296, β = − 0.499) predicted the knee extensor moment contribution (model R2 = 0.857, P < 0.001). Additionally, the combination of trunk flexion (ΔR2 = 0.429, β = − 0.613) and AP-COP position (ΔR2 = 0.109, β = − 0.332) predicted the knee extensor moment contribution (model R2 = 0.538, P < 0.001). The limb symmetry index of the knee extensor moment was significantly associated with that of the AP-COP position (R2 = 0.493, P < 0.001) but not with that of the ankle dorsiflexion angle (P = 0.057).ConclusionsThe AP-COP position can predict the contribution of the knee extensor moment and improve the prediction when combined with ankle dorsiflexion and trunk flexion. The present findings suggest that intervention focusing on the AP-COP position in combination with ankle dorsiflexion or trunk flexion would be useful to coordinate the contribution of the knee extensor moment during double-leg squatting.

Lower extremity coordination and joint kinetic distribution during gait in adults with and without Prader-Willi Syndrome

Individuals with Prader-Willi Syndrome (PWS) have reduced mobility, which may be due to altered gait biomechanics. This study compared lower extremity intersegmental coordination and joint kinetics in adults with and without PWS. Walking biomechanics were evaluated in 10 adults with PWS and 10 controls without and 10 with obesity. The foot-shank and shank-thigh coordination was evaluated using modified vector coding and compared between groups using Kruskal-Wallis and Mann-Whitney U tests. The total support moment was summed from the ankle, knee, and hip extensor moments; and relative joint contributions were expressed as a percentage and compared between groups using one-way MANOVA. The group with PWS had greater exclusive shank segment rotation during later stance compared with controls with (p < 0.001) and without obesity (p < 0.001). The group with PWS also had a smaller absolute total support moment than controls with obesity during early and late stance (both p < 0.001), and lower normalized total support moment compared to controls without obesity during early stance (p = 0.019) and compared to controls with obesity during late stance (p = 0.004). Extensor moment contributions was similar between groups during early and late stance (all p > 0.05). Findings suggest a flat-footed gait pattern in PWS during late stance, which may negatively influence propulsion and speed. Moreover, those with PWS had lower total support moments than controls during early and late stance, but similar relative extensor contributions when walking at self-selected speeds. As such, improving overall torque generation in the lower extremity may be useful to improve stability and mobility during gait in PWS.

Modified Biering-Sorenson Protocol Changes Joint Contributions to Total Support in Individuals with a History of Anterior Cruciate Ligament Reconstruction During Drop Vertical Jump Landings.

BackgroundThere are persistent deficits of the proximal musculature in individuals with anterior cruciate ligament reconstruction. Previous research has shown that proximal musculature fatigue alters drop vertical jump performance in healthy individuals. It is unknown how proximal musculature fatigue will alter drop vertical jump performance in individuals who have undergone anterior cruciate ligament reconstruction.Hypothesis/PurposeThe purpose of this study was to examine the effects of a proximal extensor musculature fatigue protocol on drop vertical jump landing biomechanics of individuals with a history of anterior cruciate ligament reconstruction using both single-joint parameters and total support moment analysis.Study DesignQuasi-experimental pre-post laboratory experimentMethodsNineteen participants with a history of unilateral anterior cruciate ligament reconstruction were recruited. Three-dimensional motion analysis was performed bilaterally during a drop vertical jump. Participants then completed a proximal extensor musculature fatigue protocol and immediately repeated the drop vertical jump task. Sagittal plane kinetics and kinematics were collected. Joint contributions to peak total support moment were calculated. A condition-by-limb repeated measures analysis of variance was performed to explore the effects of the fatigue protocol, using an alpha level of 0.05.ResultsThere were no interactions observed for any parameters. However, the injured limb demonstrated less vertical ground reaction force (13%, p=0.013) and reduced peak dorsiflexion angle (2°, p=0.028) both before and after the protocol. After the fatigue protocol both limbs demonstrated reduced hip extensor contribution to peak total support moment (4%, p=0.035).ConclusionsIndividuals with a history of anterior cruciate ligament reconstruction performed the drop vertical jump with an altered anti-gravity support strategy after the proximal extensor musculature fatigue protocol. The significant reduction in bilateral hip extensor contribution to peak total support moment suggests evidence of targeted fatigue.Level of EvidenceIII

Association between quadriceps function, joint kinetics, and spatiotemporal gait parameters in young adults with and without obesity

BackgroundIndividuals with obesity have impaired gait and muscle function that may contribute to reduced mobility and increased fall risk. Research questions(1) what is the difference in spatiotemporal gait parameters and joint kinetics between individuals with and without obesity; (2) what is the association between spatiotemporal gait parameters, joint kinetics, and quadriceps function? MethodsForty-eight young adults with obesity (BMI = 33.0 ± 4.1 kg/m2) and 48 without obesity (BMI = 21.6 ± 1.7 kg/m2) completed assessments of quadriceps function (peak torque and early/late rate of torque development (RTD)) and walking biomechanics at self-selected speed. Spatiotemporal gait parameters (stance time, double support time, double support to stance ratio, step width, step length, cadence, and gait stability ratio (GSR)) and joint kinetics (total support moment, and relative contribution from extensor moments) were compared using one-way MANOVAs. Partial correlation examined the association between the total support moment and quadriceps function, and spatiotemporal gait parameters controlling for sex and speed. ResultsIndividuals with obesity walked with longer stance (p = 0.01), longer double-limb support (p < 0.001), wider steps (p < 0.001), lower cadence (p = 0.03), and a greater absolute (p < 0.001) but lesser normalized total support moment (p = 0.03) compared with adults without obesity. In those with obesity, greater PT was associated with less double limb support (p = 0.011) and smaller double support to stance ratio (p = 0.006); greater early RTD was associated with less double limb support (r = −0.455, p = 0.0021), less stance time (r = −0.384, p = 0.008), and a smaller double support to stance ratio (r = −0.371, p = 0.011). In those without obesity, a larger total support moment was associated with longer step length (r = 0.512, p < 0.001), lesser cadence (r = −0.497, p < 0.001), and smaller GSR (−0.460, p = 0.001). SignificanceIndividuals with obesity walk with altered spatiotemporal gait parameters and joint kinetics that may compromise stability. Extended periods of support may be a strategy used by individuals with obesity to increase stability during gait and accomodate insufficient quadriceps function.

Altered lower extremity biomechanics following anterior cruciate ligament reconstruction during single-leg and double-leg stop-jump tasks: A bilateral total support moment analysis

BackgroundInjury to the anterior cruciate ligament (ACL) can lead to long-lasting biomechanical alterations that put individuals at risk of a second ACL injury. Examining the total support moment may reveal between- and within-limb compensatory strategies. MethodsTwenty-six participants who were cleared to return to sport following ACL reconstruction were recruited. Each participant completed the single-leg and double-leg stop jump tasks. These tasks were analyzed using force plates and a 3D motion analysis system. The total support moment was calculated by summing the internal moments of the hip, knee and ankle at peak vertical ground reaction force. FindingsInternal knee extensor moment was lower in the involved limb compared to the uninvolved for both tasks (17.6%, P = 0.022; 18.4%, P = 0.008). No significant between-limb differences were found for the total support moment. The involved limb exhibited an 18.2% decrease in knee joint contribution (P = 0.01) and a 21.6% increase in ankle joint contribution (P = 0.016) to the total support moment compared to the uninvolved limb in the single-leg stop jump task. InterpretationCompensation for the involved knee is likely due to altered biomechanics that redistributes load to the uninvolved knee or to adjacent joints of the same limb. A partial shift in joint contribution from the knee to the ankle during the single-leg stop jump task demonstrates a tendency to decrease load to the knee. Further studies are needed to investigate how these adaptations impact the prevalence of subsequent injury and poor joint health.

Assessment of biomechanical deficits in individuals with a trans-tibial amputation during level gait using one-dimensional statistical parametric mapping.

Most previous studies reported biomechanical deficits in individuals with a trans-tibial amputation (TTA) during gait using zero-dimensional analyses. However, these analyses do not allow to precisely determine during which part of the gait cycle these deficits occur. There is a need to use more appropriate methods to map the differences, such as one-dimensional statistical parametric mapping. What are the most relevant phases of the gait cycle during which the biomechanical deficits in TTA occur? Eight TTA and 15 healthy counterparts (CON) underwent one biomechanical gait analysis. Pelvis, hip, knee and ankle kinematics, total support moment (TSM) and gastrocnemius lateralis, vastus lateralis and tibialis anterior muscle activity were compared between the amputated (AmLL), the intact (InLL) and the control (CnLL) lower limbs using one-dimensional statistical parametric mapping. More ankle dorsiflexion and knee flexion were observed for the AmLL compared to the InLL and CnLL (ankle only) from the end of the stance phase to the beginning of the swing phase. Less knee flexion was also found for the AmLL during early stance phase. More pelvis posterior tilt and rotation toward the contralateral limb was observed during most of the gait cycle for the AmLL compared to the InLL. TSM was smaller for the AmLL compared to the CnLL during early stance phase. Using a one-dimensional statistical parametric mapping approach for TTA gait analysis, this study provides novel insights on their biomechanical gait deficits compared to CON. Greater reliance on the InLL was observed in TTA as suggested by the asymmetric kinematic and kinetic profiles.

Longitudinal study of knee load avoidant movement behavior after total knee arthroplasty with recommendations for future retraining interventions

BackgroundThis study aimed to evaluate clinical and biomechanical changes in self-report survey, quadriceps strength and gait analysis over 3- and 6-months post-total knee arthroplasty (TKA) and confirm the immediate effects of two forms of kinetic biofeedback on improving inter-limb biomechanics during a physically demanding decline walking task. MethodsThirty patients with unilateral TKA underwent testing at 3- and 6-months following surgery. All underwent self-report survey, quadriceps strength and gait analysis testing. Patients were assigned to one of two types of biofeedback [vertical ground reaction force (vGRF), knee extensor moment (KEM)]. ResultsNo decrease in gait asymmetry was observed in non-biofeedback trials over time (p > 0.05), despite significant improvements in self-report physical function (p < 0.01, Cohen d = 0.44), pain interference (p = 0.01, Cohen d = 0.68), numeric knee pain (p = 0.01, Cohen d = 0.74) and quadriceps strength (p = 0.01, Cohen d = 0.49) outcomes. KEM biofeedback induced significant decrease in total support moment (p = 0.05, Cohen f2 = 0.14) and knee extensor moment (p = 0.05, Cohen f2 = 0.21) asymmetry compared to using vGRF biofeedback at 6-months. vGRF biofeedback demonstrated significant decrease in hip flexion kinematic asymmetry compared to KEM biofeedback (p = 0.05, Cohen f2 = 0.18) at 6-months. ConclusionGait compensation remained similar from 3- to 6-months during a task requiring greater knee demand compared to overground walking post-TKA, despite improvements in self-report survey and quadriceps strength. Single session gait symmetry training at 6-month supports findings at 3-month testing that motor learning is possible. KEM biofeedback is more effective at immediately improving joint kinetic loading compared to vGRF biofeedback post-TKA.

Kinetics, kinematics, and knee muscle activation during sit to stand transition in unilateral and bilateral knee osteoarthritis

BackgroundThe sit to stand transition (STS) is a task performed by those with knee osteoarthritis (KOA) with biomechanical modifications that may influence the lower limb load distribution. As a weight bearing task mainly performed in the sagittal plane, the presence of unilateral or bilateral KOA may lead to asymmetry during its performance. Research questionAre the biomechanical and neuromuscular aspects of the sit to stand transition (STS) different between participants with unilateral and bilateral KOA? MethodsTwenty-eight participants were allocated as follows: unilateral KOA (OAUNI; n = 12) and bilateral KOA (OABI; n = 16). All participants were evaluated by means of kinematics (Qualisys Motion Capture System, Qualisys Medical AB, SUE), kinetics (Bertec Corporation's model 4060−08 Mod., USA), and electromyography (TrignoTM Wireless System, DelSys Inc., USA) during the STS. The variables calculated were the symmetry indices of the total support moment (TSM) and ground reaction force (ISGRF and ISTSM, respectively), magnitude of the TSM, individual joint contribution to the TSM, peak trunk flexion, hip, knee, and ankle range of motion, duration in seconds, the magnitudes of activation of the extensor and flexor muscles, knee extensors: flexor co-contraction indices and isometric knee extensor peak torques. Participants also answered the WOMAC questionnaire and performed the 30-second STS test (STS30). ResultsThe OABI got up from a chair with a lower TSM magnitude in the most affected limb (p = 0.040), used greater trunk flexion amplitude (p ≤ 0.034), and presented lower isometric KET (p = 0.039) and worse self-reported pain (p = 0.011) and physical function (p = 0.015). SignificanceParticipants with unilateral and bilateral KOA differ regarding lower limb kinetics and trunk kinematics while getting up from a chair, without modification in the lower limb intersegmental coordination or symmetry regarding ground reaction force or TSM distribution.

Ankle, knee, and hip contribution to ambulatory support moment and MRI-detected structural worsening 2 years later in knee OA

Purpose: During walking, extensor moments generated at the ankle, knee and hip are responsible for vertically supporting the body and advancing the body center of mass forward. Support moment (SM) is the sum of ankle, knee, and hip extensor moments when the limb accepts full body weight during gait (Figure 1). To maintain adequate SM, lower moment at one joint may be compensated by greater moment at the other. Cross-sectional studies have shown that persons with knee OA, compared to healthy controls, have increased ankle and decreased knee contribution to the total SM during walking.

Altered gait mechanics are associated with severity of chondropathy after hip arthroscopy for femoroacetabular impingement syndrome

BackgroundSuboptimal patient-reported function and movement impairments often persist after hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Individuals with FAIS with preoperative cartilage pathology (ie. chondropathy) demonstrate distinct movement patterns and have worse post-operative outcomes. It is unknown whether the presence of chondropathy after surgery negatively affects movement and function. Research questionDo sagittal plane gait mechanics differ based on chondropathy severity following arthroscopy for FAIS? MethodsA cross-sectional walking gait analysis was performed for 25 participants post-arthroscopy (2.48 ± 1.38y) and 12 healthy controls (HCs). Peak total support moment (TSM) and relative contributions of the hip, knee, and ankle were calculated during loading response. The Hip Osteoarthritis MRI Scoring System was used to categorize the FAIS group into no-mild or moderate-severe chondropathy groups based on 3 T magnetic resonance imaging of their surgical hip. The interactions of group by limb were evaluated for kinetic variables, covaried by gait speed. ResultsGroups did not differ based on age, BMI and sex distribution (P ≥ 0.14). 13 participants with FAIS presented with moderate-severe chondropathy and 12 presented with no-mild chondropathy. Participants with moderate-severe chondropathy walked significantly slower than both other groups (P = 0.006) and demonstrated lower peak TSM than those with no-mild chondropathy (P = 0.002). Participants with no-mild chondropathy demonstrated lower hip (61.5 %) and greater ankle (17.7 %) contributions to the TSM on the involved limb compared to the moderate-severe group (hip:73.4 %, P = 0.07; ankle:10.5 %, P = 0.007). SignificanceSlower gait speed alone did not explain the lower TSM strategy in participants with moderate-severe chondropathy. Interestingly, the joint contribution strategy of this group was not different than HCs. Participants with no-mild chondropathy demonstrated a TSM strategy that shifted the demand away from their hip and toward their ankle. Given the small sample size, and large variability in joint strategies, future work needs to examine whether these alterations in gait strategy, with or without advanced chondropathy, impact patient function.

Individual joint contributions to the total support moment during the sit-to-stand task differentiate mild and moderate knee osteoarthritis

BackgroundKnee osteoarthritis tends to modify the kinematics and kinetics of the sit-to-stand task. However, it is not clear whether the different degrees of knee osteoarthritis differentiate regarding these aspects. The objective was to identify if the trunk flexion, lower limb kinetics, total support moment, and individual joint contributions to the total support moment during the sit-to-stand task are different between patients with mild and moderate knee osteoarthritis. MethodsSixty-two participants were grouped as follows: moderate knee osteoarthritis (n = 16), mild knee osteoarthritis (n = 25), and controls (n = 21). The participants performed a sit-to-stand task, which was analyzed using a 3D-motion system and a force plate. FindingsThe three phases of the sit-to-stand task were analyzed. During Phase1, the moderate osteoarthritis group decreased the total support moment (P = 0.012). During Phase2, the moderate osteoarthritis group showed higher trunk flexion (P = 0.023) and lower internal hip and knee extension moments (P ≤ 0.001 and P ≤ 0.040, respectively) when compared to controls. Also in Phase2, both the mild and moderate groups used lower total support moment (P = 0.019, and P ≤ 0.001, respectively). When compared to the controls and mild osteoarthritis group, those with moderate osteoarthritis presented higher hip joint contribution to the total support moment (P ≤ 0.001 and P = 0.006, respectively) as well as lower knee joint contribution (P ≤ 0.003 and P = 0,013, respectively). InterpretationThose with moderate osteoarthritis showed modified sit-to-stand movement pattern. While in Phase3 a higher contribution of the hip joint to the total support moment was observed, during previous phases the individuals were able to decrease the load on the knee without influencing the lower limb load distribution.

Step descent strategy is altered bilaterally despite unilateral muscle strength impairment after total knee arthroplasty.

Muscle weakness and difficulty descending stairs are common after unilateral total knee arthroplasty (TKA), but the relationship between each is unclear. The purpose of this study was to compare lower extremity muscle strength, lower extremity support moments during step descent, and assess relationships between each. The study included 40 subjects (20 post-TKA, 20 control). Knee extensor, hip abductor, and hip external rotator strength were measured and biomechanical analyses of step descent performed. Patients with TKA were assessed 3 and 6months post-surgery. At 3 and 6months post-TKA, operated limb hip external rotator and knee extensor strength were impaired compared to the non-operated limb (p < 0.01); however, no between-limb differences were observed during step descent. Compared to the control group, hip external rotator and knee extensor strength, total lower extremity support moment, and knee support moment during step descent were impaired post-TKA (p < 0.05). At 6months post-TKA, knee extensor and hip external rotator strength correlated with total support moment during step descent (rs = 0.40, 0.41, p < 0.02). Hip abductor and external rotator strength negatively correlated with knee support moment during step descent (rs = - 0.35, - 0.39, p < 0.03). Persistent operative limb knee extensor and hip external rotator muscle weakness are noted following unilateral TKA. Despite unilateral weakness, bilateral alterations in step descent strategy occur following TKA. Patients with TKA utilize hip musculature to reduce knee muscle demand during step descent, possibly contributing to limitations in long-term step descent performance.

Changes in total lower limb support moment in middle-aged patients undergoing arthroscopic partial meniscectomy — A longitudinal observational cohort study

BackgroundPatients with a meniscal tear are frequently treated with arthroscopic partial meniscectomy (APM) which may alter the net extension moment across the entire lower limb – known as the total support moment (TSM). PurposeTo investigate changes in TSM during walking in patients undergoing APM. MethodsThree-dimensional motion analysis of walking was performed in individuals with meniscal tear prior to APM and 12 months after. Peak TSM, positive ankle (ASM), knee (KSM), and hip (HSM) moments at the time of peak TSM were calculated together with corresponding angular impulses. ResultsPatients (n = 20) were middle aged (45.9 ± 6.3 years) and the majority male (70%). At baseline a lower KSM (mean [95%CI]; 0.59 Nm/BM · HT% [−1.93; 3.11], P = 0.048) and a trend towards lower peak TSM (0.46 Nm/BM · HT% [−1.82; 2.78], P = 0.099) were observed for the APM leg compared with the contralateral. Pre- versus post-APM change scores indicated a relative decrease in loading of the contralateral leg for peak TSM (−0.49 Nm/BM · HT% [−0.96; −0.01], P = 0.047) and a trend towards a relative increase in loading of the APM leg for peak KSM (−0.41 Nm/BM · HT% [−0.92; 0.09], P = 0.105). No differences were observed in angular impulse variables. ConclusionsPrior to APM a strategy to unload the injured knee was manifested by reduced KSM and a tendency to a reduced peak TSM. A more equal distribution of joint moments between injured and contralateral legs was observed 12 months following APM.