THE INFLUENCE OF KNEE FLEXION CONTRACTURE ON SPINAL ALIGNMENT

Abstract

Purpose: The purpose of this study was to investigate the relationship between knee flexion contracture and spinal alignment.

Methods: Ten healthy women (mean age 62) participated in this study. Subjects were examined with posture analysis system, using twelve retro-reflective markers (placed at bilateral acromion, bilateral anterior and posterior superior iliac spine, iliaccrest, greater trochanter, lateral knee joint, lateral malleolus, lateral calcaneus, and fifth metatarsal head), five cameras and a force plate. Unilateral (only right side) knee flexion contractures were simulated by using a hard brace at 0, 15 and 30 degrees. First, relaxed standing was measured without simulation, and then the same measurement was performed with each simulation. The posture without brace was used as control. The shoulder tilting angle was defined by the height difference in right and left acromions. The pelvic tilting angle was defined by the height difference in right and left superior posterior iliac spines. The anterior-bent of the trunk was defined by the slope linked right acromion and right iliac crest. The posterior-bent of the pelvis was defined by the slope linked right superior anterior iliac spine and right superior posterior iliac spine. Knee resultant force (% body weight) was calculated by using inverse dynamics technique.

Results: When contracture angle increased, the trunk was significantly tilted leftward (1.4 degrees at 30 degrees contracture), and the pelvis was significantly tilted rightward (1.8 degrees at 30 degrees contracture). In anterior-bent of the trunk, no significant difference was detected. The posterior-bent of the pelvis was significantly increased (1.5 degrees at 30 degrees contracture). The severer the right knee contracture, the smaller the right knee resultant force (41.5 at controls, 28.7 at 30 degrees contracture) and the larger the left knee resultant force (40.2 at controls, 59.9 at 30 degrees contracture).

Conclusions: This study showed the influence of knee flexion contracture not only in the sagittal plane, as the previous study reported, but also in the coronal plane. Severe unilateral knee flexion contracture can cause the lumbar spine bent convexly to the contracture side. This may result in Knee-Spine Syndrome.