In knee OA , strong evidence was found that avoidance of activities is associated with activity limitations via muscle weakness ( mediation by muscle weakness ) , strong evidence was found for an association between muscle weakness and activity limitations , and weak evidence was found that pain and psychological distress are associated with muscle weakness via avoidance of activities ( mediation by avoidance ) .
In hip OA , weak evidence was found for mediation by muscle weakness ; and strong evidence was found for an association between muscle weakness and activity limitations .
The avoidance model in patients with knee and hip osteoarthritis ( OA ) hypothesizes that pain and psychological distress lead to avoidance of activities , and thereby to muscle weakness and activity limitations .
This paper systematic ally review s the scientific evidence for the validity of this avoidance model .
Quadriceps strength and the risk of cartilage loss and symptom progression in knee osteoarthritis.
OBJECTIVE To determine the effect of quadriceps strength in individuals with knee osteoarthritis ( OA ) on loss of cartilage at the tibiofemoral and patellofemoral joints ( assessed by magnetic resonance imaging [ MRI ] ) and on knee pain and function . METHODS We studied 265 subjects ( 154 men and 111 women , mean+/-SD age 67+/-9 years ) who met the American College of Rheumatology criteria for symptomatic knee OA and who were participating in a prospect i ve , 30-month natural history study of knee OA . Quadriceps strength was measured at baseline , isokinetically , during concentric knee extension . MRI of the knee at baseline and at 15 and 30 months was used to assess cartilage loss at the tibiofemoral and patellofemoral joints , with medial and lateral compartments assessed separately . At baseline and at followup visits , knee pain was assessed using a visual analog scale , and physical function was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index . RESULTS There was no association between quadriceps strength and cartilage loss at the tibiofemoral joint . Results were similar in malaligned knees . However , greater quadriceps strength was protective against cartilage loss at the lateral compartment of the patellofemoral joint ( for highest versus lowest tertile of strength , odds ratio 0.4 [ 95 % confidence interval 0.2 , 0.9 ] ) . Those with greater quadriceps strength had less knee pain and better physical function over followup ( P<0.001 ) . CONCLUSION Greater quadriceps strength had no influence on cartilage loss at the tibiofemoral joint , including in malaligned knees . We report for the first time that greater quadriceps strength protected against cartilage loss at the lateral compartment of the patellofemoral joint , a finding that requires confirmation . Subjects with greater quadriceps strength also had less knee pain and better physical function over followup
In knee OA , strong evidence was found that avoidance of activities is associated with activity limitations via muscle weakness ( mediation by muscle weakness ) , strong evidence was found for an association between muscle weakness and activity limitations , and weak evidence was found that pain and psychological distress are associated with muscle weakness via avoidance of activities ( mediation by avoidance ) .
In hip OA , weak evidence was found for mediation by muscle weakness ; and strong evidence was found for an association between muscle weakness and activity limitations .
The avoidance model in patients with knee and hip osteoarthritis ( OA ) hypothesizes that pain and psychological distress lead to avoidance of activities , and thereby to muscle weakness and activity limitations .
This paper systematic ally review s the scientific evidence for the validity of this avoidance model .