Linking biomechanics to mobility and disability in people with knee osteoarthritis

Influence of Walking Over Unexpected Uneven Terrain on Joint Loading for Individuals With Transtibial Amputation

Individuals with transtibial amputation (TTA) experience asymmetric lower-limb loading which can lead to joint pain and injuries. However, it is unclear how walking over unexpected uneven terrain affects their loading patterns. This study sought to use modeling and simulation to determine how peak joint contact forces and impulses change for individuals with unilateral TTA during an uneven step and subsequent recovery step and how those patterns compare to able-bodied individuals. We expected residual limb loading during the uneven step and intact limb loading during the recovery step would increase relative to flush walking. Further, individuals with TTA would experience larger loading increases compared to able-bodied individuals. Simulations of individuals with TTA showed during the uneven step, changes in joint loading occurred at all joints except the prosthetic ankle relative to flush walking. During the recovery step, intact limb joint loading increased in early stance relative to flush walking. Simulations of able-bodied individuals showed large increases in ankle joint loading for both surface conditions. Overall, increases in early stance knee joint loading were larger for those with TTA compared to able-bodied individuals during both steps. These results suggest that individuals with TTA experience altered joint loading patterns when stepping on uneven terrain. Future work should investigate whether an adapting ankle-foot prosthesis can mitigate these changes to reduce injury risk.

EFEITOS DA ORIENTAÇÃO DA ATIVIDADE FÍSICA EM PACIENTES COM OSTEOARTRITE AVANÇADA DO JOELHO

RESUMO Introdução: A osteoartrite (OA) do joelho atinge 20% da população mundial e 70% a 80% dos indivíduos com mais de 65 anos. Caracteriza-se por dor e incapacidade funcional determinada pela degeneração da cartilagem articular e do osso subcondral. Seu tratamento conservador inclui a prática de exercícios físicos. Objetivo : Determinar os efeitos da prescrição e orientação da atividade física em pacientes com OA avançada do joelho. Métodos: Foram incluídos 23 pacientes submetidos a atividade física com orientação e avaliados no momento inicial, aos três e aos seis meses, pelo sistema de pontuação EVA e WOMAC (3 domínios). Foi utilizado o modelo linear generalizado e nas situações com diferença significante entre os tempos de avaliação, foram feitas comparações múltiplas com o teste de Bonferroni, com nível de significância de cinco por cento. Resultados : Houve diferença estatisticamente significante entre as pontuações EVA e WOMAC no início do estudo e aos três e seis meses. Esses resultados foram independentes do grau de OA e de doença uni ou bilateral. Conclusão : A orientação da atividade física no tratamento de pacientes com OA avançada de joelho, melhora a função articular e deve ser considerada inclusive nos casos com indicação de artroplastia.

Improved gait in persons with knee related mobility limitations by a rosehip food supplement: A randomized, double-blind, placebo-controlled trial

PURPOSE

To evaluate the efficacy of a specialized rosehip powder nutraceutical on the biomechanical function of the knee joint during walking in individuals with knee-related walking limitations.

METHODS

Randomized, participant and outcome assessor blinded trial. Participants with self-reported knee-related walking limitations were randomized (1:1) to receive three capsules/day of either rosehip powder or identically appearing placebo capsules for 12 weeks. At baseline and the 12 weeks follow-up, 3-dimensional gait analyses were performed from which the peak resultant knee moment was selected as primary outcome. Secondary outcomes included sagittal and frontal plane knee joint moments, knee joint kinematics, peaks in the vertical ground reaction forces, and self-selected walking speeds. Analyses were based on ANCOVA with the 'Intention-To-Treat' (ITT) population, defined as all randomized participants using last observation carried forward imputation for missing data.

RESULTS

100 participants were randomized to rosehip (n=50) or placebo (n=50) and defined the ITT population. Of these 94 completed the study (47 in each group). There were statistically significant group differences in the change from baseline in the primary outcome: the resultant knee moment (0.06 nm/kg, 95%CI: 0.00-0.12; P=0.039) and in the peaks in the sagittal plane moments and kinematics during the stance phase of walking with the rosehip group exhibiting greater joint moments and more knee joint flexion during walking than the placebo group.

CONCLUSION

A daily intake of rosehip powder for 12 weeks improved important indices of knee joint function and dynamics during walking compared to placebo in persons with knee-related walking limitations.

Resistance exercise for knee osteoarthritis

The initiation, progression, and severity of knee osteoarthritis (OA) have been associated with decreased muscular strength and alterations in joint biomechanics. Chronic OA pain may lead to anxiety, depression, fear of movement, and poor psychological outlook. The fear of movement may prevent participation in exercise and social events, which could lead to further physical and social isolation. Resistance exercise (RX) has been shown to be an effective intervention both for decreasing pain and improving physical function and self-efficacy. RX may restore muscle strength and joint mechanics while improving physical function. RX also may normalize muscle firing patterns and joint biomechanics, leading to reductions in joint pain and cartilage degradation. These physical adaptations could lead to improved self-efficacy and decreased anxiety and depression. RX can be prescribed and performed by patients across the spectrum of OA severity. When designing and implementing an RX program for a patient with knee OA, one should consider both the degree of OA severity and the level of pain. RX, either in the home or at a fitness facility, is an important component of a comprehensive regimen designed to offset the physical and psychological limitations associated with knee OA. Unique considerations for this population include (1) monitoring pain during and after exercise, (2) providing days of rest when disease flares occur, and (3) infusing variety into the exercise regimen to encourage adherence.

The Influence of Radiographic Severity on the Relationship between Muscle Strength and Joint Loading in Obese Knee Osteoarthritis Patients

Objective. To investigate the relationship between knee muscle strength and the external knee adduction moment during walking in obese knee osteoarthritis patients and whether disease severity influences this relationship. Methods. This cross-sectional study included 136 elderly obese (BMI > 30) adults with predominant medial knee osteoarthritis. Muscle strength, standing radiographic severity as measured by the Kellgren and Lawrence scale, and the peak external knee adduction moment were measured at self-selected walking speed. Results. According to radiographic severity, patients were classified as “less severe” (KL 1-2, N = 73) or “severe” (KL 3-4, N = 63). A significant positive association was demonstrated between the peak knee adduction moment and hamstring muscle strength in the whole cohort (P = .047). However, disease severity did not influence the relationship between muscle strength and dynamic medial knee joint loading. Severe patients had higher peak knee adduction moment and more varus malalignment (P < .001). Conclusion. Higher hamstring muscle strength relates to higher estimates of dynamic knee joint loading in the medial compartment. No such relationship existed for quadriceps muscle strength. Although cross sectional, the results suggest that hamstrings function should receive increased attention in future studies and treatments that aim at halting disease progression.

Patients with osteoarthritic knees have shorter orientation and tangent indicatrices during gait

BACKGROUND

This study introduces two novel outcomes that could be used to identify people with knee osteoarthritis from healthy controls. These outcomes examine the lengths of paths on a sphere derived from knee angle and knee position during gait.

METHODS

Participants with moderate knee osteoarthritis (n=47) and no knee pathology (n=51) walked overground. The time-varying orientation matrices and position vectors of the knee (leg relative to the thigh) were measured, then arclength (constant speed) parameterized. The orientation matrix column aligned with the long axis of the leg, and the tangent, normal and binormal vectors (Frenet Frame) along the position vectors were calculated. These unit length vectors all scribe paths (indicatrices) on a unit sphere. The path lengths of these indicatrices, for all or part of a gait cycle, were the novel outcomes. A stepwise discriminant analysis defined a linear function that included those outcomes that best allocated a participant to the osteoarthritis or control group.

FINDINGS

Group differences were best detected with the indicatrix lengths associated with the orientation of the leg's long axis over a gait cycle (P<0.001) and the tangent vector over the stance phase (P=0.014). Both outcomes were smaller in the knee osteoarthritis compared to control group. Walking speed was poorly correlated with all indicatrix lengths (rho<|0.484|) and a discriminate analysis correctly classified 83.7% of the participants.

INTERPRETATION

Smaller indicatrix measures distinguished those with knee osteoarthritis from healthy controls. These outcomes introduce a promising new kinematic approach when examining gait data.