Date Published: March 20, 2018
Author(s): Freyja Hálfdanardóttir, Dan K. Ramsey, Kristín Briem.
The purpose of this study was to examine the influence of trunk lean and contralateral hip abductor strength on the peak knee adduction moment (KAM) and rate of loading in persons with moderate medial knee osteoarthritis. Thirty-one males (17 with osteoarthritis, 14 controls) underwent 3-dimensional motion analysis, strength testing of hip abductors, and knee range of motion (ROM) measures, as well as completing the knee osteoarthritis outcome score (KOOS). No differences were found between groups or limbs for gait cycle duration, but the osteoarthritis group had longer double-limb support during weight acceptance (p < 0.001) and delayed frontal plane trunk motion towards the stance limb (p < 0.01). This was reflected by a lower rate of loading for the osteoarthritis group compared to controls (p < 0.001), whereas no differences were found for peak KAM. Trunk angle, contralateral hip abductor strength, and BMI explained the rate of loading at the involved knee (p < 0.001), an association not found for the contralateral knee or control knees. Prolonged trunk lean over the stance limb may help lower peak KAM values. Rate of frontal plane knee joint loading may partly be mediated by the contralateral limb's abductor strength, accentuating the importance of bilateral lower limb strength for persons with knee osteoarthritis.
Osteoarthritis (OA), knee OA in particular, is a large and growing public health concern. Notable increases in estimated years lived with disability owing to OA has been observed over the last 15 years  with concomitant activity limitations projected to increase . Moreover the economic burden associated with knee OA is expected to rise concurrently with the ageing population, resulting in increased demand for primary and revision knee joint arthroplasty . Therefore, emphasis has been focused on investigating whether conservative biomechanical modalities mediate disease progression [4, 5].
Data for this cross-sectional laboratory study were collected during baseline measurements of patients who had been referred by orthopedic specialists for a fitting and trial treatment with an unloader (valgus) brace . Due to limited number of female patients at the clinic who were inclined to try an unloader brace, a decision was made to include only males in this study. Seventeen male patients (aged 40–60 years) with confirmed medial knee OA, Kellgren Lawrence (KL) grade 2 or 3 radiographic changes , and clinical history of pain and functional impairments fulfilled the inclusion criteria. In cases where bilateral radiographic knee OA was diagnosed, the more symptomatic knee denoted the affected one. Patients were excluded if they had joint replacement surgery, periarticular fracture, osteotomy, knee ligament reconstruction, or arthroscopic surgery to any lower limb joint within 6 months of the study. Exclusion criteria also included radiologically confirmed OA in the ankle or hip joints, intra-articular corticosteroid or viscosupplementation injection to either knee joint within 3 months of study participation, or any musculoskeletal or neurological impairment, dermatological or circulatory problems in the lower extremities that might affect ambulation. Fourteen asymptomatic male subjects were recruited from the university community to serve as controls (CTRL) and were matched to the OA cohort by age (to within 5 years), weight (to within 5 kilograms), and height (to within 5 centimeters).
No differences were found for mean age, height, mass, BMI, or strength between groups (Table 1). A significant deficit of knee ROM was evident on the involved side of OA participants as reflected by a group by limb interaction (F = 11.824, p = 0.002). Moreover, the CTRL group scored significantly higher on all KOOS subscales than the OA group, reflecting expected differences in self-reported knee related symptoms, functional abilities, and quality of life (p < 0.001). The main results of the study demonstrated that persons with moderate medial knee OA exhibit different movement patterns for frontal plane trunk lean compared to healthy controls. This strategy may assist in maintaining the KAM for this group to levels similar to that of controls during walking. Moreover, the rate of frontal plane knee joint loading during WA may be mediated, in part, by the contralateral limb's abductor strength. In order to maintain KAM levels near normal levels, persons with moderate knee OA may benefit from strategies that lower the rate of knee joint loading. Part of this strategy may be achieved by prolonged double stance during WA and altered timing, not degree, of frontal plane trunk motion to affect the magnitude of knee joint loading. Strength of hip abductors may influence their ability to maintain a prolonged trunk position over the stance limb and provide eccentric control while lowering the pelvis prior to contralateral WA, which may also assist in slowing down the rate of loading and controlling peak KAM values. Source: http://doi.org/10.1155/2018/4526872