Mechanical Engineering - Research Publications

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    Are Knee Biomechanics Different in Those With and Without Patellofemoral Osteoarthritis After Anterior Cruciate Ligament Reconstruction?
    Culvenor, AG ; Schache, AG ; Vicenzino, B ; Pandy, MG ; Collins, NJ ; Cook, JL ; Crossley, KM (WILEY-BLACKWELL, 2014-10)
    OBJECTIVE: Patellofemoral (PF) osteoarthritis (OA) is prevalent following anterior cruciate ligament reconstruction (ACLR). This study aimed to investigate differences in transverse plane rotation between knees with varus and valgus alignment during gait in people with and without PFOA after ACLR. METHODS: Thirty-six individuals who were mean ± SD 9 ± 2 years post-ACLR (18 radiographic PFOA and 18 no knee OA) participated in this cross-sectional study. Knee internal-external rotation angles were measured using a 3-dimensional motion analysis system during walking and running. Weight-bearing frontal plane knee alignment, measured with an inclinometer, was used to classify participants as having varus or valgus alignment. Two-way analysis of covariance was used to assess the effect of both PFOA and frontal plane knee alignment on dynamic knee internal-external rotation. RESULTS: Significant interactions were found between PFOA status and frontal plane alignment on knee internal-external rotation angles during walking (P = 0.019) and running (P = 0.002). Tests of simple effects revealed that during walking, individuals with valgus alignment and PFOA demonstrated a mean 3.9° (95% confidence interval [95% CI] 0.7, 7.1) less knee internal rotation than those with valgus alignment and no OA. During running this difference increased to 6.1° (95% CI 1.8, 10.4). For individuals with varus alignment, no significant effects were observed. CONCLUSION: Less knee internal rotation during gait was found in individuals with PFOA and valgus alignment. A rotational shift of this magnitude may be sufficient to initiate or accelerate patellofemoral cartilage degeneration. Prospective studies are required to determine if these altered kinematic patterns result from, or contribute to, PFOA development after reconstruction.
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    The effects of a varus unloader brace for lateral tibiofemoral osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction: a single case study
    Hart, HF ; Ackland, DC ; Schache, AG ; Pandy, MG ; Collins, NJ ; Crossley, KM (JMNI, 2013-12)
    We investigated the immediate effects of a varus knee brace on knee symptoms and knee-joint biomechanics in an individual with predominant lateral tibiofemoral joint osteoarthritis (TFJOA) and valgus malalignment after anterior cruciate ligament (ACL) reconstruction. A varus unloader brace was prescribed to a 48-year-old male with predominant lateral radiographic and symptomatic TFJOA and valgus malalignment eight-years following ACL reconstruction. During a step-down task, the participant rated knee pain, task-difficulty, knee-stability and knee-confidence on four separate visual analogue scales. Quantitative gait analysis was conducted during self-selected walking trials under three test conditions in a randomized order: (i) no brace; (ii) brace without frontal plane adjustment (no varus re-alignment); and (ii) brace with frontal plane adjustment (varus re-alignment). Post-processing of gait data involved calculation of knee kinematics and net joint moments for the reconstructed limb. The participant reported improved pain (3%), task difficulty (41%), stability (46%) and confidence (49%) when performing the step-down task with the brace. The varus brace resulted in immediate reductions in knee abduction angle (24%) and internal rotation angle (56%), and increased knee adduction moment (18%). These findings provide preliminary evidence for potentially beneficial effects of bracing on knee-symptoms and biomechanics in individuals with lateral TFJOA after reconstruction.