Do final rehabilitation volumes influence function after anterior cross ligament reconstruction? A pilot study

Abstract Introduction Rupture of the anterior cruciate ligament (ACL) is one of the frequent traumatic injuries of the knee joint complex, and the isokinetic dynamometer is essential to assess and measure its joint function. Objective To analyze the volume of physical therapy treatment using the same protocol with different duration in patients undergoing ACL reconstruction. Methods This is a prospective observational cohort study. The sample consisted of 13 adult male individuals who underwent ACL reconstruction surgery. Participants were divided into two groups: accelerated treatment (AC) and non-accelerated treatment (NAC). Participants underwent a standardized protocol of post-reconstruction physio-therapy, starting in the immediate postoperative period. The AC group performed the treatment three times a week, with a duration of 4 hours each session for 6 months, while the NAC performed twice a week with duration of two hours each session for eight months. Results The groups showed the same behavior during the post-reconstruction treatment periods, showing that regardless of time, the results were beneficial at the end of the treatment. However, in the accelerated protocol, the injured limb showed a significant difference for extender peak torque (PTEXT) in the preoperative and 4-month postoperative period (230.5 vs 182.6), 4-month postoperative period and final (182.6 vs 242.1) in the AC group, while in the NAC group there was no significant difference between times in this same limb. Conclusion Greater volumes of weekly training characterized better results, showing that rehabilitation time is not a predictor of discharge, but rehabilitation time obtains good results for the variables.


Introduction
Rupture of the anterior cruciate ligament (ACL) is one of the most frequent traumatic injuries in the knee joint complex.Surgical reconstruction aims to restore the functional stability of the knee and can be performed using different techniques and graft sites.1,2 According to international standards and consensus, postoperative ACL rehabilitation is usually performed between 9 and 12 months after surgery.Consequently, long-term rehabilitation protocols for patients with ACL reconstructed are strongly recommended.3 On the other hand, accelerated rehabilitation promotes pain relief, recovers active joint mobility, muscle strength and the individual's proprioceptive capacity, allowing them to return to their activities in a short period when compared to non-accelerated rehabilitation.4 However, the process of returning to physical and sports activities is not based on time, but on the individual's ability to achieve goals, and the time required for this diverges according to the particularities of each one.
Rehabilitation after ACL injuries aims to restore muscle strength, improve neuromuscular control, restore range of motion and allow a return to pre-injury activity levels.5 Patients usually return to activities and sports after reaching muscle strength with a deficit of less than 10-15% compared to the contralateral side, but strength is not the only factor to be considered.6 The isokinetic dynamometer is considered the gold standard for strength assessment, being essential to measure knee joint function and rebalance.Isokinetic assessment is essential during ACL rehabilitation, as it is a safe, reproducible and objective assessment method, measuring parameters such as peak torque (Nm), total muscle work (Joules) and muscle power (Watts).7 Given the aforementioned facts, the objective of this study was to observe whether different volumes of physiotherapeutic treatment using the same protocol in patients undergoing ACL reconstruction would result in better rehabilitation from the point of view of muscle performance components (peak torque, power and work) by the isokinetic dynamometer.

Methods
This pilot study was approved by the Human Research Ethics Committee at the Universidade Estadual do Norte do Paraná (opinion number 4.312.851).The sample was selected for convenience and composed by 13 adult male individuals who were recreational athlete and underwent surgery to reconstruct the anterior cruciate ligament.Exclusion criteria were patients with a history of neurological disease (stroke, degenerative diseases of the central nervous system or peripheral nervous system), who were using medication for psychotropic purposes during the treatment period or who were hypertensive.The sample was defined by convenience.Participants were divided into two groups, one undergoing accelerated treatment (AC; n = 8) and the other non-accelerated (NAC; n = 5).

Rehabilitation program
All participants underwent a standardized protocol of physical therapy (Appendix Functional training was progressively performed after the application of some criteria, such as symmetry, ability to jump on one leg without pain, absence of edema, pain, and full range of motion assessed by clinical examination.
In the final phase of treatment, patients started training with the sport specificity in a dynamic way, using balls, trampoline and other instruments on the ground and on the field.All exercises were gradually progressed and carefully according to the patient's tolerance.The addition of intense exercises safety and effectiveness were fully monitored and prior to the performance they were accompanied by verbal feedback to help the patient to develop safe movements.

Isokinetic evaluation
The isokinetic evaluation took place in the laboratory The larger the effect size, the greater the impact that the central variable is having and the more important the fact that it has a contribution to the analyzed issue.

Results
Data referring to the sample number and anthropometric profile (age, weight, height and fat percentage) were collected during the first isokinetic assessment and are detailed in Table 1.The sample was considered homogeneous with no significant differences between groups.
during the treatment period, with this increase being greater in the NAC group (15%) compared to the AC (4.8%) from the preoperative period to the end.For PTFLX, the gain in I was progressive, showing an increase of 16.9% in the AC protocol and 12.1% in the NAC at the end of the treatment.In the NI, both protocols showed a significant increase in PT, 6.7% for AC and 20.9% for NAC; although AC rehabilitation stood out for gain of PT in I compared to NAC for NI.The two maintained the same results during rehabilitation and no significant differences were found between groups.
In Table 3, the results of the intra and intergroup analysis for potency (POT) in Watts show that both EXT and FLX are represented.POTEXT in AC rehabilitation for L showed a progressive increase from the beginning to the end of the treatment of 17.2%, being significant from the postoperative period of 4 months to the end, with a difference of 16.3%.In NAC rehabilitation, there was a significant reduction of 32.9% from pre to postoperative period of 4 months, and an increase of 30.6% to the end, almost equivalent to the reduction values.
For POTFLX, L in the AC treatment showed a progressive improvement in all evaluation periods, all of which were significant, while in the NAC rehabilitation a tendency to reduction was observed, which decreased by 8.1% when comparing the preoperative period with the final period.In the NI from the preoperative period to the end of rehabilitation, the AC group showed a significant increase of 9.6%, while the NAC treatment had a reduction of 8.1%.Therefore, AC rehabilitation was more beneficial to POTFLX for both the injured leg and the uninjured leg.Although both groups showed reductions during the treatment periods, accelerated rehabilitation presented smaller reductions, being more beneficial for POTEXT in both limbs.
The results of total work (TT) in Joules, of EXT and FLX are shown in Table 4.In both groups, there were reductions from the preoperative to the 4-month postoperative period, both for the extensor and for the flexor.For TTEXT in AC rehabilitation for I, there was a 9.5% reduction between the pre and postoperative period of 4 months, but between the pre and the end, and postoperative period of 4 months to the end there was an improvement of 6.6% and 17.9% respectively, being significant in the second case.Also for this limb, for NAC rehabilitation there was a significant reduction of 24.4% between the pre and postoperative period of 4 months and a significant increase of 30.6% from the  Table 2 shows the results of the intra and intergroup analysis of variance for the peak torque (PT) in Nm, for both knee extensors (EXT) and knee flexors (FLX) muscles.Regarding extender peak torque (PTEXT), in AC rehabilitation, the injured limb (I) showed a tendency to increase throughout the treatment, with 12.4% higher values when comparing the pre and the final stages.
However, the difference was not significant.As for the NAC protocol for this same limb, from the preoperative to the 4-month post-operative period, there was a significant loss of 20.7% for PTEXT.However, during the rehabilitation period there was an increase of 32.5% from the 4-month postoperative period to the end of treatment.The uninjured limb (NI), on the other hand, showed a tendency to maintain or increase its strength postoperative period of 4 months to the end.Although there was an increase during the treatment, when comparing the initial value to the end, a loss of 1.2% in the injured limb was verified.For NI in AC rehabilitation, there was a reduction during the entire treatment period, being significant from pre to postoperative period of 4 months.In NAC rehabilitation, there was an improvement of 2.2% from pre to end of treatment.Therefore, although it showed a significant reduction between pre and post, AC rehabilitation still showed improvements at the end of the treatment for I.
For TTFLX, the I in AC rehabilitation progressively increased during treatment, resulting in a significant increase of 16.6% from postoperative period of 4 months to the end, and 17.5% when comparing pre and end of treatment.In the NAC rehabilitation, there was a progressive reduction during the treatment, being 2.9% when comparing the pre and end of treatment.In the NI limb for both groups there was a reduction in the postoperative values, with an increase after 4 months to the end.However, when evaluated pre and end of treatment, the AC gained 1.3% and the NAC lost 7.6%.Thus, for TTFLX gain, AC rehabilitation proved to be more effective for limb I and NI.
Regarding bilateral deficits at the end of treatment, for the PT of the extender group, the participants of the NAC had bilateral deficits greater than the AC, which was above the recommended in the literature.For this same variable, both the knee extensors and the knee flexors, the values were close to what was expected, being better in the flexors.As for the PT, the deficits are also within the ideals.However, the participants of the AC group presented better results.
The agonist-antagonist relationship is shown in Table 5.It is possible to observe that, in the preoperative period, both NI and I had similar values in both groups, showing that all participants had values close to PT.In the 4-month postoperative period, the I of the NAC group had higher values than the AC, which is related to the significant reductions in PTEXT values.With the progressive increase in the EXT values from 4 months after the end of treatment, an improvement in the agonist-antagonist ratio in both groups can also be observed.showing that changes in strength will lead to changes in these abilities.Accordingly, it is important that during rehabilitation goals are set for these abilities, in addition to strength.
The hamstring/quadriceps muscles strength ratio has been used as an indicator of balance.12 It is a very significant parameter in estimating the time to return to sports activities.At the end of the treatment, our patients had results close to those expected for the population at the recommended level that allows them to return to sports activities.In the knee, the ratio between the peak torque of the flexors/extensors should be around 60%.Therefore, the difference between the extensors and the flexors should not be greater than 40%.13-15 In the uninjured limb, the ratio with lower values can be explained by the dominance of the limbs.A large part of our sample had the dominant limb uninjured, and in these cases, the knee extensor muscles are stronger due to dominance, providing a lower agonist/antagonist ratio.Although they presented a lower ratio for the uninjured limb, the participants maintained joint stability.
In fact, the goal of rehabilitation was fulfilled, as both groups improved at the end and there was no significant difference between the groups in any of the evaluated moments.The reductions presented at the end of the treatment are within the expected range in the literature, between 10 and 15%, 16 showing that the patients maintained joint rebalancing, despite the reductions during treatment.Isokinetic assessment is a great method to treatment when it comes to ACL postoperative period, as it allows to objectively quantify the variables and describe them throughout the physical therapy treatment.Furthermore, it is recommended that the isokinetic knee evaluation be used as one of the criteria to decide whether the patient should return to activities or not.17 • Cryotherapy guidance at home with compression 4 times per day for 20 min; • Hip, knee and ankle active-assisted mobilization orientation with an auxiliary device (crutch); • At the end of the second week, start proprioception while standing, keeping the weight bearing at 30%.Laser HeNe around the stitches and scan on the stitches; • Punctual AsGa laser over the graft tendon and scan over it; • US 1mHz pulsed in case of resorbable screw; • Manual lymphatic drainage • Fascia release and thigh and leg massage; • Light transverse massage around the scar after removing the stitches.
• Active-assisted hip mobilization against gravity with slight manual resistance; • Side lying hip and knee mobilization with mild progressive manual resistance associating with PNF.
Patient performs hip flexion and knee flexion while therapist resists; • Ankle mobilization; • Multidirectional patellar mobilization; • Fibular head mobilization; • Active-assisted knee mobilization to pain limit; • Active-assisted knee mobilization with elastic band on the calcaneus; of the Health Sciences Center at the Universidade Estadual do Norte do Paraná (CCS-UENP) in the preoperative period, in the 4-month postoperative period, and at the end, in the 6-month postoperative period in the AC group and in the 8-month postoperative period in the NAC group.The same evaluators performed the bilateral knee evaluation during all periods, using a Biodex Multi-Joint Pro isokinetic dynamometer.Participants were evaluated for knee flexion and knee extension using the following protocol: prior to the test, an active warm-up for 5 minutes using an exercise bike with an intensity of 50 J and then the evaluation was started.Participants were evaluated in a sitting position.Stabilization straps were applied to the trunk and thighs, and a resistance pad placed at a level of 3 cm above the malleolus.All participants underwent uninvolved limb testing first and the knee range of motion during the test was set to 0-90°.Bilateral tests (concentric/concentric) of knee extension and knee flexion were performed with the protocol of 60°/s (5 repetitions) and 180°/s (5 repetitions), with a 30 seconds interval between sets.Verbal encouragement during the test was consistent and standardized.Peak torque (Nm), muscle power (Watts), total work (Joules) and agonist/antagonist ratio, automatically calculated by the device, were analyzed.Statistical analysisStatistical analysis was performed using the SPSS 20.0 statistical program.The Shapiro-Wilk test was used to verify data normality, which are presented as mean and standard deviation.The analysis of variance test for repeated measures was used to compare the moments of assessment (pre, post-4 months and post-6 months or post-8 months) for the AC and NAC groups.The independent t test was used to compare NAC and AC groups for all variables in both limbs (injured and uninjured).An additional analysis was used to observe the effects of time, group and time x group, which are presented in graphs.Analysis of variance (ANOVA) for FISIOTERAPIA EM MOVIMENTO Physical Therapy in Movement Souza RM et al.Fisioter Mov.2023;36:e36125 4 repeated measures was used, in which the assumption of sphericity was tested using the Mauchly test.In case of violation of the sphericity assumption, the Greenhouse-Geisser correction was used.When necessary, the posthoc Bonferroni test was used.Eta square (ES) values greater than or equal to 0.14 represent large effect size.
Note: Values expressed as mean ± standard deviation.

Figure 1 Figure 1 - 2 3FISIOTERAPIA
Figure 1 shows the results of the analysis of sphericity for the groups in time and time*group.The time 1 represents the preoperative period, time 2 the
Russian current on vast medial, vast lateral and vast intermediate (6 points) requesting internal, external rotations and neutral knee position.Sitting position with feet off the stretcher, cushion below the popliteal fossa, requesting knee extension when supporting the chain.Physical therapist maintains manual support if necessary; • Russian current on hamstrings (4 points) with internal and external rotations.Position: prone position with supra patellar pad, requesting maximum flexion; • Eccentric contraction of hamstrings training with guidance and manual support with resistance; • CORE training in supine position (bridge with bipedal support); • Start abdominal strengthening; • Standing proprioception with support, on the parallel bar;

Table 1 -
Anthropometric profile for the accelerated (AC) and non-accelerated (NAC) groups

Table 5 -
Analysis of intra and intergroup variances for the agonist/antagonist ratio