The time spent, activities selected, and modalities or physical agents chosen during the PT session were based on the patient’s needs and progress toward his/her functional goals. Manual therapy techniques consisted of soft-tissue mobilization, passive ROM, joint mobilization, passive stretching, scar mobilization, manual resistive exercises, and proprioceptive neuromuscular facilitation techniques. Therapeutic exercises/activities consisted of lower extremity resistance exercises (weight bearing and non-weight bearing), ROM exercises, stretching, balance, stair training, agility, activities of daily life (ADL) training, and a comprehensive home exercise program. Modalities or physical agents used during this study included moist hot packs, cold packs, ultrasound, electrical stimulation, and Kinesio Tape. Physical agents were incorporated into the individual’s plan of care based on medical necessity when deemed appropriate by the treating therapist. The exercise prescription was based on an individual’s status and tolerance and the number of sets and repetitions were based on fatigue.
Gait Training
The patients were randomized (1:1) to either land-based or anti-gravity gait training. For the control group, land-based gait training was performed with or without an appropriate AD and appropriate assistance, tactile cueing, and verbal cueing from a physical therapist. Duration (minutes) and gait-training progression were dependent on the participant’s functional goals, pain level (assessed throughout treatment), and level of fatigue. For the AlterG group, gait training was performed in the AlterG Anti-Gravity Treadmill, M320 (Alter-G; Figure 1). On day 1, the AlterG pressure chamber was set to allow only 50% of the patient’s body weight to be transmitted to the treadmill floor, and speed was controlled by the patient according to his/her comfort level. The percentage of body weight was adjusted to allow for a safe and normalized gait pattern with a pain level no greater than 5 (0 to 10 scale) throughout the PT session. A report card was recorded at each PT session, including body-weight setting (%), speed (miles per hour), incline (%), and duration (minutes) (Figure 2). For subsequent visits, the body-weight setting was started from the end point of the previous session.
Data Collection and Analysis
SPSS version 12.0 (SPSS Inc.) was used for all analyses, and an alpha level of .05 determined statistical significance when comparing group differences. The safety and feasibility of the anti-gravity (AlterG) vs land-based (control) gait training was assessed by the presence (or absence) of adverse events (AEs) and complications, and the date the patient discontinued use of his/her AD. A chi-square test was used to assess differences between control and AlterG groups regarding patient discontinuance of an AD. Additionally, for patients randomized to AlterG, a report card summarized means and frequencies for body weight, speed, incline, and duration. At EOPT, the frequency of therapists who were satisfied with the AlterG Anti-Gravity Treadmill as part of the rehabilitation protocol was reported. The preliminary effects of gait training (land-based vs anti-gravity) during postoperative rehabilitation on functional outcomes (subjective patient outcomes assessed by KOOS, mobility assessed by the TUG test, and pain assessed by a NRS) were evaluated by independent sample t tests. Paired sample t tests were used to compare each of the functional outcomes at EOPT or EOS to the baseline value.
Results
Of the 30 patients enrolled, 29 (96.7%; 29/30) patients completed the study; 1 patient, who could not complete all PT sessions because of medical and transportation issues, was excluded. The remaining 29 patients comprised the study population (control = 15; AlterG = 14). All patients were compliant with PT protocols.
Patient demographics were similar between the control and AlterG groups (Table 1). The control group comprised 9 women (60%; 9/15) and 6 men (40%; 6/15), age 69.9 ± 7.8 years and a body mass index of 28.8 ± 4.2. Similarly, the AlterG group comprised 7 women (50%; 7/14) and 7 men (50%; 7/14), age 66.5 ± 7.8 years and a body mass index of 28.4 ± 5.2.
At the baseline PT visit, patients in the control and AlterG groups had similar KOOS, TUG, and NRS scores. At baseline, mean KOOS for symptoms, pain, sports/recreation, ADL, and quality of life were 52.7, 52.9, 22.7, 64, and 31.8, respectively, although 50% of patients did not complete the sports/recreation subset of the KOOS. In addition, the mean time to complete the TUG test was 14.5 seconds, which was within the normal limits for disabled patients. This was slightly longer than normal mobility (TUG <10 seconds),20 but patients had relatively low levels of pain (mean NRS = 2.5, on a scale of 0-11).
All patients completed the PT protocols without indication of injury or AEs related to their operative knee. Three patients (10.3%; 3/29) experienced a deep venous thromboembolism (DVT), 2 in the control group (13.3%; 2/15), and 1 in the AlterG group (7.1%; 1/14). Venous thromboembolism protocol of enoxaparin 30 mg twice daily while in the hospital and enoxaparin 40 mg once daily for 10 days after discharge was followed for all patients.