The relation between pain and torque in an isokinetic strength test of knee extension.

Twenty-five patients (20 +/- 3 years) with patella tendinitis were followed over an 8-week period in order to study the relation between quadriceps muscle torque, in a Cybex test, and knee pain on exertion. Each patient was examined on three occasions; at 0, 4, and 8 weeks. During the first 5 weeks the patient was put through a treatment program with initial rest, activity modification, and local injection of betamethasone or Arteparon. Half of the patients improved, with less pain and higher torque, and the rest experienced no change. There was a significant negative correlation between pain and torque, stronger to measurements at 30 degrees than at 180 degrees/s (r = -0.59 and -0.40). The linear regression analysis, however, revealed that the same relative difference in pain was equivalent to a bigger difference in torque at 180 degrees than at 30 degrees/s.