KEYWORDS
Anti-Gravity Treadmill training, anterior cruciate ligament reconstruction, muscular
atrophy, balance ability, post-operative rehabilitation, knee function, cohort study
1.Summary
1.1Background:
Post-operative muscular atrophy and impaired balance are great rehabilitation challenges in patients with anterior cruciate ligament reconstruction (ACLR). Anti-gravity treadmill training (AGTT) is a novel rehabilitation therapy that provides partial body-weight support (BWS) and enhances muscular motor. The present study aims to explore the effects of AGTT rehabilitation on muscular atrophy and balance ability, as well as the outcomes of knee function, physical activity, and return to sports in ACLR patients.
1.2Methods：
This was a prospective cohort study. ACLR patients were included between January 1, 2022, and December 31, 2023, and randomly divided into the AGTT group (6-week AGTT+routine rehabilitation protocol) and control group (routine rehabilitation protocol). After a 6-week AGTT, a muscular atrophy grading system was used to estimate the severity of quadriceps femoris atrophy, and the Berg balance scale (BBS) was used to evaluate the patients’ balance ability. At 1y follow-up, the outcome functional assessments were performed, including Lachman and pivot shift test, A-P ligament laxity (KT-2000), range of motion, International Knee Documentation Committee (IKDC) score, Tegner Activity Score (TAS), and rate of returning to sports
1.3 Results:
<73 ACLR patients have completed 1y follow-up, the total missing rate was 8.75%. After 6-week AGTT, the severity of quadriceps femoris atrophy was significantly decreased in the AGTT group (18/36, grade A/all) than the control group (7/37, P = 0.003), while the BBS in the AGTT group (53.67 ± 1.00) was significantly increased than the control group (52.12 ± 1.08, P
1.4Conclusion：
A 6-week AGTT rehabilitation can protect the quadriceps femoris muscular atrophy and promote balance recovery in ACLR patients, resulting in better short-term outcomes of joint stability, knee function, physical activity level, and return to sports
2.Materials and Methods
Patient involvement
Patients who underwent arthroscopic ACLR were included between January 1, 2022, and December 31, 2023, in the Inner Mongolia Autonomous Region People’s Hospital. The inclusion criteria were: (1) age: 18–50 years old, BMI ≤31; (2) unilateral ACL rupture, time from injury to ACLR ≤1 year; (3) ACLR with autologous double-bundle four-strand hamstring tendon; (4) agree to participate in this study after signing the informed consent; (5) agree to the arrangement of the rehabilitation subgrouping. The exclusion criteria were: (1) collateral ligament rupture or posterior ligament rupture; (2) ACL re-rupture; (3) history of lower-extremity fracture, ligament rupture, and operations of the bone-ligament system (14); (4) knee osteoarthritis with the Kellgren-Lawrence grade >2, rheumatoid arthritis, and gouty arthritis (14); (5) nerve system diseases.
Rehabilitation protocols of the two groups
AGTT was performed by an AGTT device (GA100S, Golden All, China) (Figure 1). The AGTT rehabilitation was started from the 3rd week after surgery and was conducted 3 times/week for a total duration of 6 weeks (18 sessions for each participant, 30 min/ session). AGTT rehabilitation protocols: (1) the initial 2 weeks of AGTT: walking for 30 min (speed = 0.5 km/h, BW = 20%, incline = 0%); (2) 3–4 weeks of AGTT: walking for 30 min [speed = 0.6–0.8 km/h (15), BW = 20%, incline = 0%]; (3) 5–6 weeks of AGTT: walking for 30 min [speed = 0.8–0.9 km/h (15), BW = 20%, incline = 1%–2% (15)]. To ensure the safety and efficacy during AGTT rehabilitation, one senior physiotherapist was assigned to supervise and manage the rehabilitation (Table 1).
Rehabilitation assessment on muscular atrophy
Muscular atrophy was estimated by measuring the differences of thigh circumference between the ACLR side and the contralateral side, at 10 cm above the upper border of the patella. The muscular atrophy was graded as follows: grade A (no difference), grade B (0–1 cm), grade C (1–2 cm), and grade D (>2 cm) (16). Rehabilitation assessment on muscular atrophy was performed at the end of the 8th week after ACLR (AGTT rehabilitation was also completed in the 8th week).
Rehabilitation assessment on balance ability
Berg balance scale (BBS) was used to evaluate balance ability, consisting of 14 simple functionally oriented balance tasks, beginning with “standing up” and progressing up to “stand upright without support”, “stand upright with closed eyes”, and “standing on one leg” etc. (17). Each task was scored by a fivepoint scale (0–4), and a total score between 0 and 56 was generated by summing those scores together at the end of the BBS test, a higher score indicated a better balance ability. The rehabilitation assessment on balance ability was performed at the end of the 8th week after ACLR.
Follow-ups
The follow-up was started when the ACLR operation was completed. The end was ACL re-rupture/severe complication/ death/missing/1 year (y) post operation, whichever occurred first. General clinical parameters included: age, gender, body mass index (BMI), whether combined with a meniscus tear, the graft diameter of ACLR, follow-up time, and complications.
The clinical assessments were performed at the end of the follow-up, including: the physical examination of ACL stability, ligament laxity (KT-2000), and knee range of motion (ROM), as well as the subjective scoring systems of knee function and physical activity. Outcome assessors were blinded to group assignment.
Clinical examinations of knee joint
The clinical examinations of knee stability were performed 1y post-operatively in all ACLR patients, consisting of the Lachman test and pivot shift test, which are generally used to determine the knee stability recovery after ACLR (18). Lachman test was used to assess the A-P joint stability, classified as: hard end-point (−), doubtable laxity (±), and soft end-point (+) (14). Pivot shift was used to assess the rotational stability, classified as: normal (−), glide (±), and clunk or gross (+) (19).
A-P ligament laxity was measured by KT-2000 when the knee is Pexed at 30°, by comparing it to the contralateral healthy side, classified as: normal, grade 1 (difference between 1 and 5 mm), grade 2 (between 5 and 10 mm), and grade 3 (>10 mm) (19). Knee range of motion (ROM) was measured by standardized goniometry technique in pre-operation and at 1y follow-up.
Subjective assessments of knee function
The International Knee Documentation Committee (IKDC) subjective-form score and Tegner Activity Score (TAS) were used to assess the outcome of knee function and physical activity correspondingly, at 1y follow-up (20, 21). IKDC scoring was performed by self-questionnaires with a full score of 100, and a higher score represented a better functional outcome. TAS was also performed by self-questionnaires, and a score of 10 was assigned based on the level of activity that the patient selected as best representing their current activity level, for example, a score of 0 represented “sick leave or disability pension because of knee problems”, while a score of 10 corresponded to “participation in national and international elite competitive sports” (21).
The rate of returning to sports at 1y follow-up was also used to evaluate the outcome of physical activity.
Statistical analysis
All of the statistical analyses were performed using SPSS 20.0 (SPSS Inc., 2009, Chicago, IL, USA). The continuous data were expressed as mean ± SD, and the count data (gender, combined with/without meniscus tear, muscular atrophy grading, complications, Lachman test result, Pivot shift result, A-P Laxity grading, and return to sports rate) were expressed as number (n) and rate (/). All of the continuous data in the present study were tested by the Shapiro–Wilk normality test. Intra-group comparisons of the continuous data were processed by the independent samples t-tests and Levene variance homogeneity tests between groups, while intra-group comparisons of the count data were processed by the Chisquare test or Fisher’s exact test. The level of significance was set at 0.05.
3.Results
Basic characteristics
Initially, 80 ACLR patients were continuously included in this prospective cohort study and completed the rehabilitation task, by a ratio of 1:1 in the AGTT group and control group. At 1y followup, 2 patients were missing (can not be reached in any way) and 2 patients declaimed that he/she was not living in the city during the follow-up time in the AGTT group, 1 patient was missing and 1 patient declaimed that he moved to another city, and 1 patient died of pancreatic cancer in the control group. Finally, 73 ACLR patients have completed 1y follow-up, the total missing rate was 8.75% (AGTT 4/36, Control 3/37), and the minimal follow-up was 12 months.
The basic characteristics of the AGTT group and control group were listed below, no significant difference of gender, age, BMI, whether combined with meniscus tear, graft diameter, and follow-up time was observed between the 2 groups.
Rehabilitation assessment on neuromuscular function
At the end of the 8th week after ACLR (AGTT rehabilitation was also completed at the 8th week), the rate of grade A of muscular atrophy grading system in the AGTT group was significantly higher than the control group (50.0% vs. 18.9%, P = 0.003) (Table 3), which also means the rate of grade B, C, D in the control group was significantly higher than the AGTT group (Table 3). The BBS of the AGTT group was significantly higher than that of the control group with the difference of 1.55 points (95% CI: 1.05–2.05) (Table 3).5 patients had complications during the AGTT rehabilitation period: 3 patients had transient edema, and 2 patients had transient pain (mild) of the knee joint. 8 patients had complications during the rehabilitation period in the control group: 4 patients had transient edema, 2 patients had transient pain (mild) of the knee joint, and 2 patients had experienced limited ROM (intervened by a rehabilitation therapist using manual release). All those complications were relieved or disappeared in 1 week. However, no significant difference of the complication rate was observed between the 2 groups (Table 3)
Clinical assessments on functional outcomes
At 1y follow-up, the rate of normal A-P laxity, IKDC, TAS and rate of return-to-sport in the AGTT group were significantly higher than that in the control group (Table 4). AGTT improved returnto-sport by 29 percentage points (72.2% vs. 43.2%, P = 0.012) than the control group (Table 4). The Lachman test, pivot shift test, and ROM did not show a significant difference between the 2 groups (Table 4).
4.Conclusions
The present cohort study found that the AGTT rehabilitation starting from the 3rd week in post-operation can protect quadriceps femoris muscular atrophy and promote balance recovery in ACLR patients, resulting in better short-term outcomes of joint stability, knee function, physical activity level, and return to sports. The variations in speed and incline of AGTT protocol may be the potential reason for the better efficacy and outcomes compared to the routine rehabilitation protocol.