Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society. 2014;22(6):742-746.
OBJECTIVES: Arthrogenous muscle inhibition (AMI) is thought to contribute to quadriceps
weakness in knee osteoarthritis (OA), but its relationship with structural changes
of bone marrow lesions (BMLs), capsular distension and pain are unclear. This study's
objectives were to investigate the factors associated with AMI in subjects with symptomatic
PFJOA. DESIGN: 126 Subjects with predominant PFJOA were assessed for pain by the visual
analogue scale (VAS) for a nominated aggravating activity. Their more symptomatic
knee underwent aÂ magnetic resonance imaging (MRI) scan which was used to assess BMLs
and synovitis which were scored using the WORMS scale. Quadriceps AMI was measured
by calculating the activation deficit and quadriceps strength assessed by isometric
maximum voluntary contraction. Multiple linear regressions were used to assess factors
associated with AMI. RESULTS: We studied 124 subjects [mean age 55.5 (SD 7.5); 57.14%
female]. In regression analyses, higher levels of AMI were significantly associated
with more severe knee pain and with lower BML score. CONCLUSION: Quadriceps AMI in
knee OA is associated with severity of knee pain and surprisingly with lower BML scores.