Biodex Balance System features a platform that can move simultaneously in the anteroposterior (AP) or medio-lateral (ML) direction in 12 different levels of stability within a 20-degree range of inclination, as well as a locked position for static environments. For this platform, 1 represents the least stable level and 12 represents the most stable level. Interactive, game-like training modes are provided with the on-screen grid and score-keeping functions. Patients in the BT group performed exercises with the Balance SystemTM SD once a day, three days a week for 10 weeks under the physicians' supervision. Furthermore this group received closed kinetic chain exercises (CKCE) in addition to their own exercise program, which was applied in exactly the same way. The CKCE were performed in three sets of 10 repetitions with five seconds rest between each exercise. The exercises consisted of mini-squats, wall sits, and lunges.

Patients in the CT group completed the exercise program once a day and three days a week during the 10-week period under the physicians' supervision. The exercises consisted of standing on one leg, tandem walking (heel-to-toe), balance board exercises, Romberg exercise, backward walking, and side-to-side stepping exercises. The total duration of these exercises was 20-30 minutes. Furthermore this group also received CKCE in addition to their own exercise program, which was applied in exactly the same way. The CKCE were performed in three sets of 10 repetitions with five seconds rest between each exercise. The exercises consisted of mini-squats, wall sits, and lunges.

Isometric home exercises, which can be considered the most basic and feasible strengthening program, were selected to compare the effects they had when added to the intervention groups and administered alone. All patients in the study performed isometric exercises for the quadriceps and hamstrings at home once a day, three days a week for 10 weeks. The exercises were performed as 10 repetitive cycles of six-second contractions and two-second rest periods. All patients were given a daily exercise chart to mark the home program, and adherence to the exercises was monitored weekly by telephone call.

Balance and proprioception exercises using two different methods (classical balance training and Biodex) in addition to strengthening exercises

The postural stability test, was performed with the following parameters: Duration: 20 seconds, Stability level: 8, and Stance: two legs. The value of overall stability index (OSI) is obtained by calculating the standard deviations of the degrees of inclination with respect to the zero point (locked position). Higher values indicate poorer equilibrium.

The postural stability test, was performed with the following parameters: Duration: 20 seconds, Stability level: 8, and Stance: two legs. The value of overall stability index (OSI) is obtained by calculating the standard deviations of the degrees of inclination with respect to the zero point (locked position). Higher values indicate poorer equilibrium.

The modified Clinical Test of Sensory Interaction and Balance (mCTSIB).The entire test is performed with the platform in the locked position. The test consists of 4 conditions: Condition 1: eyes open firm surface, Condition 2: eyes closed firm surface, Condition 3: eyes open dynamic (foam) surface, and Condition 4: eyes closed dynamic (foam) surface. The firm and dynamic surface tests assess static and dynamic balance, respectively. The conditions under which visual data are blocked are designed to detect even minor balance disturbances caused by the sensorimotor system. The sway index obtained as a result of the test represents the average position of the patient's center of mass relative to the center of the platform. Higher values indicate poorer balance. mCTSIB Condition-3, and mCTSIB Condition-4 dynamic balance assessment tests were used to assess dynamic balance.

The modified Clinical Test of Sensory Interaction and Balance (mCTSIB).The entire test is performed with the platform in the locked position. The test consists of 4 conditions: Condition 1: eyes open firm surface, Condition 2: eyes closed firm surface, Condition 3: eyes open dynamic (foam) surface, and Condition 4: eyes closed dynamic (foam) surface. The firm and dynamic surface tests assess static and dynamic balance, respectively. The conditions under which visual data are blocked are designed to detect even minor balance disturbances caused by the sensorimotor system. The sway index obtained as a result of the test represents the average position of the patient's center of mass relative to the center of the platform. Higher values indicate poorer balance. mCTSIB Condition-3, and mCTSIB Condition-4 dynamic balance assessment tests were used to assess dynamic balance.

Patients' pain scores at night, at rest, and during movement were measured using visual analogue scale (VAS) (0-10 cm; 0 indicates no pain and 10 indicates severe pain).