Postural stability and responses to vibrations in patients after anterior cruciate ligament surgical reconstruction

The aim of the study was to evaluate the effect of surgical reconstruction of anterior cruciate ligament (ACL) on postural stability and responses to lower limb (LL) muscles vibrations. Centre of pressure (CoP) was measured in 17 subjects during stance on firm/foam surface with eyes open/closed and during unilateral vibrations of LL muscles (m. triceps surae - TS, m. quadriceps femoris - Q, m. quadriceps femoris and hamstrings simultaneously - QH). The measurements were performed: 1) preoperatively, 2) six weeks and 3) three months after the reconstruction. Decreased postural stability was documented six weeks after the reconstruction compared to preoperative measurement. Three months after the reconstruction significant improvement was observed during stance on foam surface with eyes closed. Preoperatively, altered reactions of LL with ACL lesion compared to intact LL were manifested by slower response in first 3 s of TS vibration and by increased CoP shift in last 5 s of QH vibration. After the reconstruction, we observed slower CoP reaction and decreased CoP shift during TS vibration of LL with ACL lesion compared to preoperative level. Posturography during quiet stance and during TS vibration reliably detect postural changes due to ACL reconstruction and can be potentially useful in clinical practice.