Neil R. Bergman

Foot posture in people with medial compartment knee osteoarthritis

BackgroundFoot posture has long been considered to contribute to the development of lower limb musculoskeletal conditions as it may alter the mechanical alignment and dynamic function of the lower limb. This study compared foot posture in people with and without medial compartment knee osteoarthritis (OA) using a range of clinical foot measures. The reliability of the foot measures was also assessed.MethodsThe foot posture of 32 patients with clinically and radiographically-confirmed OA predominantly in the medial compartment of the knee and 28 asymptomatic age-matched healthy controls was investigated using the foot posture index (FPI), vertical navicular height and drop, and the arch index. Independent t tests and effect size (Cohens d) were used to investigate the differences between the groups in the foot posture measurements.ResultsSignificant differences were found between the control and the knee OA groups in relation to the FPI (1.35 ± 1.43 vs. 2.46 ± 2.18, p = 0.02; d = 0.61, medium effect size), navicular drop (0.02 ± 0.01 vs. 0.03 ± 0.01, p = 0.01; d = 1.02, large effect size) and the arch index (0.22 ± 0.04 vs. 0.26 ± 0.04, p = 0.04; d = 1.02, large effect size). No significant difference was found for vertical navicular height (0.24 ± 0.03 vs. 0.23 ± 0.03, p = 0.54; d = 0.04, negligible effect size).ConclusionPeople with medial compartment knee OA exhibit a more pronated foot type compared to controls. It is therefore recommended that the assessment of patients with knee OA in clinical practice should include simple foot measures, and that the potential influence of foot structure and function on the efficacy of foot orthoses in the management of medial compartment knee OA be further investigated.

Increased inflammatory cytokine expression in the vastus lateralis of patients with knee osteoarthritis

OBJECTIVE Increased inflammation and pain are inseparable parts of knee osteoarthritis (OA) that may lead to disuse of the affected limb. The aim of this study was to examine the effects of knee OA on inflammation- and atrophy-related genes and proteins in the vastus lateralis muscle of patients with knee OA. METHODS Nineteen patients with knee OA and 14 asymptomatic control subjects matched for age and body mass index underwent strength measurements and a muscle biopsy. Muscle was analyzed for the total cellular protein of inflammatory kinases (p65 NF-κB, JNK1/2, STAT-3, and suppressor of cytokine signaling 3 [SOCS-3]) and inflammatory intracellular molecules (interleukin-6 [IL-6], IL-8, monocyte chemoattractant protein 1 [MCP-1], tumor necrosis factor α [TNFα], IL-1β, and atrogin-1). RESULTS Knee OA resulted in greater levels of IL-6 protein (34%; P = 0.002). The levels of inflammatory kinases, including STAT-3 (187%; P = 0.002), p65 NF-κB (156%; P = 0.002), and JNK1 (179%; P = 0.027), were also elevated. Furthermore, elevated expression of gene transcripts encoding MCP-1 (28%; P = 0.023), TNFα (85%; P < 0.001), and SOCS-3 (38%; P = 0.055) was observed in patients with knee OA compared with control subjects. Patients with knee OA had reduced muscle strength compared with control subjects (mean ± SEM 84.7 ± 8.7 versus 143.1 ± 20.8 Nm; P = 0.005). Negative correlations were observed between muscle strength and MCP-1 protein abundance (r = -0.37 [P = 0.042]) and the gene expression of TNFα and atrogin-1 messenger RNA (r = -0.46 [P = 0.012] and r = -0.36 [P = 0.040], respectively). CONCLUSION Gene expression and the protein abundance of numerous muscle markers of inflammation and atrophy were elevated in patients with knee OA, and the increase in muscle inflammation was associated with a reduction in muscle strength. Given the role inflammation markers may play in muscle strength and atrophy, further studies are needed to investigate the effect of exercise intervention on skeletal muscle inflammation.

Foot kinematics in people with medial compartment knee osteoarthritis

OBJECTIVES Foot orthoses are commonly used in the management of knee OA, although the relationship between foot function and knee OA is still unclear. The purpose of the study was to examine foot function during walking in people with and without medial compartment knee OA. METHODS Motion of the tibia, rearfoot and forefoot in 32 patients with medial compartment knee OA and 28 age-matched control subjects was investigated. Multivariate analysis was used to compare the groups. RESULTS The knee OA group contacted the ground with a more everted rearfoot, demonstrated greater peak rearfoot eversion and exhibited reduced rearfoot frontal plane range of motion and reduced rearfoot peak inversion. The tibia was more internally rotated and laterally tilted throughout the gait cycle, with reduced peak external rotation. CONCLUSION People with medial compartment knee OA exhibit altered foot kinematics during gait that are indicative of a less mobile, more everted foot type. The presence and degree of tibial malalignment and the available rearfoot range of motion during walking may affect individual responses to load-altering interventions, such as foot orthoses and footwear modifications. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry, www.anzctr.org.au/, ACTRN12608000116325.

Relationship between foot function and medial knee joint loading in people with medial compartment knee osteoarthritis

BackgroundDynamic joint loading, particularly the external knee adduction moment (KAM), is an important surrogate measure for the medio-lateral distribution of force across the knee joint in people with knee osteoarthritis (OA). Foot motion may alter the load on the medial tibiofemoral joint and hence affect the KAM. Therefore, this study aimed to investigate the relationship between tibia, rearfoot and forefoot motion in the frontal and transverse planes and the KAM in people with medial compartment knee OA.MethodMotion of the knee, tibia, rearfoot and forefoot and knee moments were evaluated in 32 patients with clinically and radiographically-confirmed OA, predominantly in the medial compartment. Pearson’s correlation coefficient was used to investigate the association between peak values of tibia, rearfoot and forefoot motion in the frontal and transverse planes and 1st peak KAM, 2nd peak KAM, and the knee adduction angular impulse (KAAI).ResultsLateral tilt of the tibia was significantly associated with increased 1st peak KAM (r = 0.60, p < 0.001), 2nd peak KAM (r = 0.67, p = 0.001) and KAAI (r = 0.82, p = 0.001). Increased peak rearfoot eversion was significantly correlated with decreased 2nd peak KAM (r = 0.59, p < 0.001) and KAAI (r = 0.50, p = 0.004). Decreased rearfoot internal rotation was significantly associated with increased 2nd peak KAM (r = −0.44, p = 0.01) and KAAI (r = −0.38, p = 0.02), while decreased rearfoot internal rotation relative to the tibia was significantly associated with increased 2nd peak KAM (r = 0.43, p = 0.01). Significant negative correlations were found between peak forefoot eversion relative to the rearfoot and 2nd peak KAM (r = −0.53, p = 0.002) and KAAI (r = −0.51, p = 0.003) and between peak forefoot inversion and 2nd peak KAM (r = −0.54, p = 0.001) and KAAI (r = −0.48, p = 0.005).ConclusionIncreased rearfoot eversion, rearfoot internal rotation and forefoot inversion are associated with reduced knee adduction moments during the stance phase of gait, suggesting that medial knee joint loading is reduced in people with OA who walk with greater foot pronation. These findings have implications for the design of load-modifying interventions in people with knee OA.

Lower Limb Biomechanics in Individuals With Knee Osteoarthritis Before and After Total Knee Arthroplasty Surgery

We investigated the biomechanical changes that occur in the lower limb following total knee arthroplasty (TKA). Lower limb joint kinematics and kinetics were evaluated in 32 patients before and 12 months following TKA and 28 age-matched controls. Analysis of variance with Bonferroni-adjusted post-hoc tests showed no significant changes in knee joint kinematics and kinetics following TKA despite significant improvements in pain and function. Significant increases in peak ankle plantarflexion and dorsiflexion moments and ankle power generation were observed which may be a compensatory response to impaired knee function to allow sufficient power generation for propulsion. Differences in knee gait parameters may arise as a result of the presence of osteoarthritis and mechanical changes associated with TKA as well as retention of the pre-surgery gait pattern.

Association between skeletal muscle inflammatory markers and walking pattern in people with knee osteoarthritis.

Patients with knee osteoarthritis (OA) are characterized by increased muscle inflammation and altered gait. We investigated the association between proinflammatory mediators in the vastus lateralis and physical function and gait in patients with knee OA.

Swing limb mechanics and minimum toe clearance in people with knee osteoarthritis

OBJECTIVE Knee osteoarthritis (OA) has been shown to be a risk factor for falls. Reductions in foot clearance during the swing phase of walking can cause a trip and potentially lead to a fall. This study examined the swing phase mechanics of people with and without knee OA during walking. DESIGN Minimum toe clearance (MTC) height, joint angles at the time of MTC and the influence of the angular changes of the hip, knee and ankle of the swing leg on foot clearance using sensitivity analysis were investigated in 50 knee OA participants and 28 age-matched asymptomatic controls. RESULTS Although both groups had a similar MTC height (controls: 12.8±6.7 mm, knee OA: 13.4±7.0 mm), the knee OA group used a different strategy to achieve the same foot clearance, as evidenced by greater knee flexion (52.5±5.3° vs 49.4±4.8°, p=0.007), greater hip abduction (-3.6±3.3° vs -1.8±3.3°, p=0.03) and less ankle adduction (2.8±1.9° vs 4.2±2.1°, p=0.01). CONCLUSION MTC height was comparable between the groups, however a different swing phase mechanism was used by the knee OA. Although adequate MTC is an important component of safe locomotion, it does not appear to be impaired in people with knee OA. Other factors, such as inadequate responses to postural perturbation, may be responsible for falls in this group.

The effects of osteoarthritis and age on skeletal muscle strength, Na+-K+-ATPase content, gene and isoform expression

Knee osteoarthritis (OA) is a debilitating disorder prevalent in older populations that is accompanied by declines in muscle mass, strength, and physical activity. In skeletal muscle, the Na(+)-K(+) pump (NKA) is pivotal in ion homeostasis and excitability and is modulated by disuse and exercise training. This study examined the effects of OA and aging on muscle NKA in 36 older adults (range 55-81 yr), including 19 with OA (69.9 ± 6.5 yr, mean ± SD) and 17 asymptomatic controls (CON, 66.8 ± 6.4 yr). Participants completed knee extensor strength testing and a physical activity questionnaire. A vastus lateralis muscle biopsy was analyzed for NKA content ([(3)H]ouabain binding sites), α1-3- and β1-3-isoform protein abundance (immunoblotting), and mRNA (real-time RT-PCR). The association between age and NKA content was investigated within the OA and CON groups and in pooled data. The NKA content was also contrasted between subgroups below and above the median age of 68.5 yr. OA had lower strength (-40.8%, P = 0.005), but higher NKA α2- (∼34%, P = 0.006) and α3-protein (100%, P = 0.016) abundance than CON and performed more incidental physical activity (P = 0.035). No differences were found between groups for NKA content, abundance of other NKA isoforms, or gene expression. There was a negative correlation between age and NKA content within OA (r = -0.63, P = 0.03) and with both groups combined (r = -0.47, P = 0.038). The NKA content was 25.5% lower in the older (69-81 yr) than in the younger (55-68 yr) subgroup. Hence older age, but not knee OA, was related to lowered muscle NKA content in older adults.

Dynamic foot function changes following total knee replacement surgery

BACKGROUND Individuals with knee osteoarthritis (OA) have flatter/more pronated feet than those without OA, but it is unclear whether altered foot posture and function are a cause or consequence of knee OA. The purpose of this study was to examine whether changes in foot posture and function occur after realignment of the knee following total knee replacement (TKR). MATERIALS AND METHODS Nineteen patients with predominantly medial compartment knee OA were tested prior to and 12 months after TKR. The Foot Posture Index (FPI) and Arch Index (AI) were measured as well as motion of the tibia, rearfoot and forefoot using a 3D motion analysis system incorporating a multisegment foot model. RESULTS There were no significant changes in FPI or AI following TKR, however gait analysis revealed significant increases in tibial external rotation (-18.7 ± 7.0° vs -22.5 ± 8.7°, p=0.002), tibial transverse plane range of motion (-9.1 ± 4.6° vs -11.4 ± 6.1°, p=0.0028) and rearfoot range of motion in the frontal plane (8.6 ± 2.6° vs 10.4 ± 2.7°, p=0.002), and a decrease in rearfoot transverse plane range of motion (8.7 ± 5.3° vs 5.9 ± 4.1°, p=0.038) following the procedure. CONCLUSIONS TKR produces no change in static foot posture, but results in significant changes in rearfoot kinematics during gait. These findings suggest that rearfoot motion compensates for changes in the alignment of the knee, highlighting the ability of the foot to accommodate for proximal skeletal malalignment.

Changes in foot posture and function following total knee replacement surgery

Background Knee malalignment and variations in foot posture and function affect the forces transmitted through the knee joint and are associated with knee pain and medial tibiofemoral cartilage damage [1]. However, it is unclear whether altered foot posture and function are a compensatory mechanism to accommodate knee malalignment. Therefore, this study investigated changes in foot posture and function after realignment of the knee following total knee replacement (TKR) in people with medial compartment knee OA.