Proprioception and stabilizing reactions of the quadriceps and hamstrings in knee osteoarthitis

ABSTRACT

Knee joint proprioception has been shown to be deficient in patients with knee osteoarthritis. This might be the outcome of the operating pathology. Proprioceptive-mediated postural evoked responses of the quadriceps and hamstring muscles may be affected by the deficient proprioception. Such impairment may have a deleterious effect on the joint integrity as these muscular responses are protective for the joint during loading. To evaluate the proprioceptive-mediated stabilizing quadriceps and hamstring muscles activity posturally evoked by support surface perturbation in patients with knee osteoarthritis. The postural-evoked response surface EMG [SEMG] of the quadriceps and hamstrings following downward perturbation of the support surface were studied in 40 patients with knee osteoarthritis and compared to 20 matching healthy control subjects. In addition, knee joint proprioception was assessed by measuring inaccuracy of reproducing target 10, 20 and 30 degrees active flexion angel while standing. Postural stability was assessed by recording parameters of the center of pressure [COP] of single legged stance using a force platform. Patients showed significantly larger SEMG normalized response amplitude [mean, for right and left 0.9517 +/- 0.45222 and 0.9411 +/- 0.40585] compared to control [0.3524 +/- 0.1408 and 0.4777 +/- 0.2663, for right and left side respectively] [Z=-3.994 and -3.035, p=0.000 and 0.002]. Patients showed significantly delayed peak latency of hamstring activation [patients mean 175.04 +/- 63.03 ms and 197, 27 +/- 59.9 ms, control mean 133.50 +/- 32.67 and 135.50 +/- 33.62, for the right and left sides respectively] [Z=-1.966 and -2.666, p=0.049 and 0.008]. In addition, significant asymmetry of activation latency and amplitude were observed in patients compared to control regarding the quadriceps and hamstring bilateral responses. Patients showed significant proprioception inaccuracy with 30 degree active knee flexion reproduction [percent proprioception inaccuracy at 30[o] target angle for patients = 12.85 +/- 10.34, control= 3.55 +/- 5.25; Z=-2.443, p=0.015]. A set of significant correlations has been found between SEMG variables and each of the COP parameters, knee joint proprioception inaccuracy as well as pain score on visual analogue scale. Abnormalities of postural-evoked quadriceps and hamstring responses were found in patients with knee osteoarthritis. Direct and indirect relationship could be emphasized between these variables and deficient knee joint proprioception. The results support the assumption that previously reported deficiency of knee joint proprioception has a significant effect on the postural-evoked responses of the quadriceps and hamstrings in patients with knee osteoarthritis. Accordingly, improvement of thigh muscles proprioceptive-mediated postural activity could be a valuable component of the rehabilitation exercises designed for those patients