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Knee biomechanics with and without patellofemoral pain

PainSci » bibliography » Nakagawa et al 2012
Tags: patellar pain, structuralism, arthritis, aging, pain problems, knee, leg, limbs, overuse injury, injury, running, exercise, self-treatment, treatment, biomechanical vulnerability

Two articles on PainSci cite Nakagawa 2012: 1. The Complete Guide to Patellofemoral Pain Syndrome2. The Causes of Runner's Knee Are Rarely Obvious

PainSci notes on Nakagawa 2012:

Research on the biomechanics of patellofemoral pain syndrome (PFPS), and almost any knee issue, has focused on movement in the "sagittal plane" (looking at someone from the side). This study decided to investigate the "frontal plane" (looking at someone from the front) movements and how they may change in someone with PFPS during a stepping task.

People with PFPS tended to have increased knee abduction (knock knees) throughout the motion, and greater trunk, pelvis and hip motion during the step down. Females were also a little weaker in the hips than males.

Interestingly, this study seemed to show that PFPS does involve altered frontal plane biomechanics. No effect sizes were reported, however, so "how much different" remains a question, but the differences certainly exist. It's not surprising — if your knee hurts, you move differently!

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

PURPOSE: The study's purpose was to compare trunk, pelvis, hip, and knee frontal plane biomechanics in males and females with and without patellofemoral pain syndrome (PFPS) during stepping.

METHODS: Eighty recreational athletes were equally divided into four groups: female PFPS, female controls, male PFPS, and male controls. Trunk, pelvis, hip, and knee frontal plane kinematics and activation of the gluteus medius were evaluated at 15°, 30°, 45°, and 60° of knee flexion during the downward and upward phases of the stepping task. Isometric hip abductor torque was also evaluated.

RESULTS: Females showed increased hip adduction and knee abduction at all knee flexion angles, greater ipsilateral trunk lean and contralateral pelvic drop from 60° of knee flexion till the end of the stepping task (P = 0.027-0.001), diminished hip abductor torque (P < 0.001), and increased gluteus medius activation than males (P = 0.008-0.001). PFPS subjects presented increased knee abduction at all the angles evaluated; greater trunk, pelvis, and hip motion from 45° of knee flexion of the downward phase till the end of the maneuver; and diminished gluteus medius activation at 60° of knee flexion, compared with controls (P = 0.034-0.001). Females with PFPS showed lower hip abductor torque compared with the other groups.

CONCLUSIONS: Females presented with altered frontal plane biomechanics that may predispose them to knee injury. PFPS subjects showed frontal plane biomechanics that could increase the lateral patellofemoral joint stress at all the angles evaluated and could increase even more from 45° of knee flexion in the downward phase until the end of the maneuver. Hip abductor strengthening and motor control training should be considered when treating females with PFPS.

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