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

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

Partial body weight-supported treadmill training for gait restoration in hemiplegic patients: evaluation of using motor evoked potentials

Partial body weight support treadmill training [PBWST] is a task-oriented gait rehabilitation protocol for hemiplegic/paretic patients with proven clinical efficiency. At the neurophysiologic level, motor-evoked potentials [MEP] induced by transcranial magnetic stimulation [TMS] and recorded from target lower limb muscles may be used to assess the post-rehabilitation effects. Assessment of the effects of PBWST on the MEPs recorded from target lower limb muscles in chronic post-stroke hemiparetics. Thirty patients with post-stroke chronic hemiparesis were randomly allocated to one of 2 groups; PBWST group and conventional rehabilitation group. Initial evaluation included recording the MEP parameters from the quadriceps, tibialis anterior and gastrocnemius muscles. In addition, functional assessment tools included Fugel-Meyer assessment [FMA], functional ambulation category as well as Standing Balance Test. Endpoint evaluation using the same methods were obtained by the completion of 8 weeks of rehabilitation at a frequency of 3 times a week. Both study groups have shown significant post rehabilitation improvement of most of the recorded MEP parameters. The magnitude of post-rehabilitation change in the PBWST group was generally larger than in the other group. Significant correlation was observed between some parameters of the MEPs and the isolated movement subset of the FMA of both groups. Post-rehabilitation tibialis anterior latency was a significant predictor of post-rehabilitation co-ordination subset of the FMA in PBWST group. Pre- and post-rehabilitation latency and amplitude of the quadriceps MEP were significant predictor of the co-ordination subset of the FMA in the conventional rehabilitation group. MEPs parameters can monitor rehabilitation effects of PBWST at the neurophysiological level. The magnitude of PBWST post-rehabilitation effects was generally higher. MEP parameters can be used as predictors of functional outcome

Effect of spinal fixation on postural patterns: a neurophysiologic study

Spinal fixation is a commonly used-procedure to manage spinal instability and mal-alignment as in spondylolisthesis and scoliosis. Restriction of the movement of the spinal segment is among its mechanical consequences. This restriction is assumed to reduce the proprioceptive output from the spine that is essential for proper postural control patterns. Was to investigate the parameters of the automatic postural response of the leg and trunk in patients who have undergone spinal fixation. Sixteen patients whose spine was fixed for management of spondylolisthesis and another 15 patients who had spinal fixation for idiopathic scoliosis were studied. Their automatic postural response parameters following backward perturbation of their erect stance, were compared with the response from 20 healthy volunteers. The study showed evidence supportive of significant deviation from normality of the automatic postural response of the patients' group. The abnormality was in the form of delayed erector spinae response latency as well as increased time gap between the trunk response and the leg response. Additionally, there was erector spinae response amplitude reduction in the patients' group. Finally, there was a statistical evidence of a tight link of the leg and trunk muscle response suggesting a stiffening pattern that was not observed among the control group. The results suggest a problem with the proprioceptive information coming out of the fixed spine that may probably be responsible for the response abnormality observed in the study. These abnormalities may put uncontrolled mechanical burden both on the trunk and the overall body balance