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

Abstract

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.

The relationship between foot and ankle symptoms and risk of developing knee osteoarthritis: data from the osteoarthritis initiative

“…Over time, this abnormal stress may damage the load-bearing tissues in the knee joint leading to pain and structural damage 13 . However, whilst some cross-sectional studies show increased foot pronation in people with knee OA 36 , and that a more pronated foot is associated with an increased prevalence of knee pain and medial tibiofemoral cartilage damage 13 , other research suggests increased pronation may instead be a compensatory mechanism designed to reduce knee load and pain 37 . Third, footwear may be a shared risk factor for both foot/ankle symptoms and knee OA.…”

Impact of Concurrent Foot Pain on Health and Functional Status in People with Knee Osteoarthritis: Data From the Osteoarthritis Initiative

“…Through this mechanism, foot pain due to excessive pronation or other biomechanical factors may occur following, in concert with, or prior to knee OA-related pain. For example, foot pronation (and subsequent pain) could be a compensatory response to OA-related knee pain, whereby the foot pronates to shift the centre of pressure and ground reaction force-knee joint lever arm more laterally, in an attempt to reduce medial knee load and pain (19). Alternatively, both foot and knee pain may be related to the presence of varus knee malalignment, which may occur with or without knee OA.…”

“…Additionally, we did not examine foot pain prevalence according the knee joint compartment affected by OA. People with medial tibiofemoral OA exhibit biomechanical characteristics that increase their risk of painful foot conditions (19, 20, 37), and therefore it is possible that prevalence of foot pain may be higher in this subgroup. Future studies may wish to examine whether foot pain prevalence differs depending on knee OA compartment.…”

“…This information is important, as it may provide insight into common clinical knee OA phenotypes and has the potential to increase our knowledge of pain presentations at these 2 common sites. For instance, while increased foot pronation, a well-recognized biomechanical risk factor for many painful foot conditions (15)(16)(17)(18), has been reported in people with medial knee OA compared to those without, studies have only explored associations between the foot and knee of the same limb (19,20). With international guidelines now recommending clinicians identify and address different clinical OA phenotypes (21), a greater understanding of the clinical presentation of people with concurrent knee OA and foot pain, and its cumulative effects upon knee OA symptoms and functional status, is needed.…”

Loading conditions of the knee: what does it mean?

“…Despite the strong correlation between the mechanical axis and the adduction moment, other factors such as increased rearfoot eversion, rearfoot internal rotation and forefoot inversion cause reduction in loading of the medial compartment [9]. Thus, it seems to make sense to perform a ''brace-test'', for instance, before high tibial osteotomy is considered in osteoarthritic knees.…”