ISOMETRIC AND ISOKINETIC QUADRICEPS STRENGTH IN GONARTHROSIS - INTERRELATIONS BETWEEN QUADRICEPS STRENGTH, WALKING ABILITY, RADIOLOGY, SUBCHONDRAL BONE-DENSITY AND PAIN

Patients with osteoarthrosis suffer from disability and pain. We measu red isokinetic and isometric peak torque in 20 women with gonarthrosis (GA) and in 26 healthy controls. Relationships between muscle strengt h, walking and stair climbing time, pain level and pain disability sco res as assessed by the patients using an extensive questionnaire, radi ological changes and subchondral sclerosis expressed as bone mineral d ensity (BMD, g/cm(2)) of the proximal tibia were studied. Precision er rors of the torque measurements in both GA patients and controls were approximately 6 %. In the GA patients, isokinetic and isometric quadri ceps strength was reduced by 40 and 15 % (p < 0.01) respectively, and walking and stair climbing time was increased by 30 % (p < 0.005). Iso kinetic strength was a better predictor of pain level and pain disabil ity scores than isometric strength and radiological stage. Walking tim e and stair climbing time were not associated with quadriceps strength , pain level, pain disability scores or radiological changes. Subchond ral BMD was not predictive of pain. The study suggests that quadriceps strength assessed by isokinetic dynamometry in GA is a reliable measu rement. Isokinetic strength was pronouncedly reduced compared to isome tric strength and was a more important predictor of pain and pain disa bility than isometric strength. These findings should be taken into co nsideration when planning exercise studies and programmes in GA.