Aquatic Therapy after Anterior Cruciate Ligament Surgery: A Case Study on Underwater Gait Analysis Using Inertial and Magnetic Sensors.

Background: Water exercise is employed as therapeutic treatment. The reduction of the body weight and the increased resistance to the movement are two representative and desirable effects of the underwater gait advantages. The aim of the present study was to propose a movement analysis methodology based on inertial and magnetic sensors to provide quantitative data on the joint kinematics of an anterior cruciate ligament injured patient. Methods: One patient operated on reconstruction of the anterior cruciate ligament performed three 10-meters-long walking trials, in dry-land and underwater conditions. A validated motion analysis protocol was used to analyze the participant 3D joint kinematics of the lower limbs during walking task, using inertial and magnetic sensors. Angular and spatio-temporal variables of hips, knees and ankles were calculated for each side. Gait patterns of healthy subjects, assumed as control group, were chosen among literature as reference. Results: The injured limb had a smaller knee flexion than that of the controlateral limb. The patient gait patterns showed differences with respect to the control group in both environmental conditions. In the underwater walking the patient gait patterns were more similar to those of the control group than in dryland walking. The range of motion for the injured and the controlateral limbs were generally larger in the underwater condition rather than in dry-land condition. Conclusion: This case study underlines that walking in underwater condition can lead an anterior cruciate ligament injured patient to increase the knee flexion-extension range of motion, and simultaneously to assume gait patterns more similar to those of the control group. As consequence of these results, this case-study enhanced the usability of the method described to provide quantitative gait data, and provided preliminary information that might be considered as a first reference for further investigations on the walking kinematics of anterior cruciate ligament injured patients.