A comparison of lower extremity muscle strength, obesity, and depression scores in elderly subjects with knee pain with and without radiographic evidence of knee osteoarthritis

Objective. To determine, in subjects with knee pain but no radiographic cha nges of tibiofemoral or patellofemoral compartment osteoarthritis (OA), whe ther mean body weight, quadriceps and hamstring strength, lower extremity m uscle mass, depression scores, and perceptions of their general health stat us differed from those of subjects with symptomatic knee OA. Methods. Subjects were 25 women and 10 men with knee pain and radiographic evidence of OA at the baseline examination, and 21 women and 16 men who had knee pain at the baseline examination but no radiographic evidence of knee OA at either baseline examination or followup evaluation performed, on ave rage, 31 months later. These individuals were a subset of a cohort of 462 i ndependently living elderly individuals recruited by telephone interview af ter random selection through random digit dialing of households in central Indiana. Data from an additional 134 subjects who had neither knee pain nor radiographic changes of OA at either the baseline or followup examination were analyzed for comparison. Lower extremity muscle strength was measured by isokinetic dynamometry, lean tissue (i.e., muscle) mass in the lower ext remities by dual x-ray absorptiometry, depression by Center for Epidemiolog y Depression (CES-D) scale, knee pain by Western Ontario McMaster Universit y OA instrument, and perceived general health status by the Medical Outcome Survey Short Form-36. Results. in contrast to those with symptomatic knee OA, those who had knee pain but no radiographic evidence of OA were less obese, had hamstring as w ell as quadriceps weakness, and had CES-D scores high enough to qualify for a diagnosis of clinical depression. Conclusion. Among subjects with knee pain but no OA - and among women in th is subset, in particular - knee pain may be a manifestation of depression, rather than of joint disease.