Comparison of postural control in unilateral stance between healthy controls and lumbar discectomy patients with and without pain

Abstract

Previous studies have demonstrated that sciatica patients have poorer postural control than healthy controls and that postural control remains unchanged 3 months after lumbar discectomy in sciatica patients. The aims of the current study were to investigate whether static balance control recovers in pain-free discectomy patients long-term after lumbar discectomy. Next is to determine whether static balance responses of asymptomatic and symptomatic lumbar discectomy patients differed from each other and from healthy controls. In addition, the influence of the extent of disc resection (unilateral/bilateral removal) and the side of operation on static balance control were investigated. Fifteen pain-free lumbar discectomy patients, 23 lumbar discectomy patients with residual pain and 72 controls performed unilateral stance tasks with eyes open and eyes closed on a force plate were taken up for the investigation. Three repetitions of a 10 s unilateral stance test were performed on each leg. Postural sway was determined. Patients were divided into three age groups. In the eyes open condition, there was no significant difference between postural sway of pain-free lumbar discectomy patients and controls (P=0.68), whereas balance of patients with pain was significantly worse than in controls (P=0.003). In the eyes closed condition, the sway in both groups of lumbar discectomy patients was significantly worse than in controls (pain-free P=0.009/painful P<0.001). No significant differences were found in postural sway between patients with unilateral and bilateral disc resection. In unilateral stance on the leg of the operated side, centre of gravity sway was not significantly different in the eyes open condition compared to the eyes closed condition, whereas in stance on the leg of the non-operated side, postural sway was significantly lower in the eyes open condition compared to the eyes closed condition. In both conditions, postural sway in the age group of 50-65 years was significantly higher than in the age groups of 30-39 years (eyes open P=0.005; eyes closed P<0.001) and 40-49 years (eyes open P=0.002; eyes closed P=0.006). There was no significant difference between the age group of 30-39 years and the age group of 40-49 years (P=0.51). As for long-term following lumbar discectomy, there is no complete recovery of postural control. Patients seem to develop visual compensation mechanisms for underlying sensory-motor deficits, which are, however, sufficient in case of pain relief only. Further study is needed to determine the cause of the balance disturbances in lumbar discectomy patients.