The Effectiveness of Preoperative Exercises on the Outcomes After Anterior Cruciate Ligament Reconstruction: A Systematic Review

* Corresponding Author: Maedeh Taghizadeh Kermani, PhD. Address: Department of Corrective Exercise and Sport Injury, Faculty of Physical Education and Sport Sciences, Bu Ali Sina University, Hamedan, Iran. Tel: +98 (915) 4486601 E-mail: maedeh.taghizadeh1988@gmail.com 1. Department of Corrective Exercise and Sport Injury, Faculty of Physical Education and Sport Sciences, Bu Ali Sina University, Hamedan, Iran. 2. Department of Sport Physiology, Faculty of Sport Sciences, Ferdowsi University, Mashhad, Iran. Ali Yalfani1 , Ahmad Ebrahimi Atri2 , *Maedeh Taghizadeh Kermani1


Introduction
ersistent quadriceps weakness has been reported as one of the limiting factors in returning to pre-injury competition level, which can last for more than 2 years after surgery. Weakness of the quadriceps not only causes P abnormal gait and loss of function, but may also be a factor in knee osteoarthritis. There is a weakness in the quadriceps in reducing the angle and torque of the knee in walking following Anterior Cruciate Ligament (ACL) reconstruction. The preoperative phase may be helpful in reducing the risk of postoperative complications and improving successful return to high-level activity. To our knowledge, this is the first systematic review study conducted to evaluate the ef-fectiveness of preoperative rehabilitation protocols to improve patient outcomes after ACL reconstruction.

Methods
This systematic review was conducted using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement guidelines. The searching was conducted in PubMed database using following keywords: ACL Preoperative exercise, Prehabilitation ACL, preoperative Protocol. The initial search yielded 442 articles on ACL reconstruction. The papers were then examined based on the entry criteria. After checking the titles, abstracts and full texts of the articles, 10 articles on the effect of preoperative ACL exercises on the postoperative outcomes were identified. Entry criteria were related to studies that examined the effects of preoperative ACL exercises on postoperative results whose designs were randomized clinical trial, observational cohort, and case-control. Studies that had no pre-surgery training protocol (with only post-surgery exercises), case reports, and review articles were omitted. Table  1 shows the criteria for entering the study based on PICO method. Physiotherapy Evidence Database (PEDro) scale was used for randomized studies to evaluate the quality of their methodology. For cohort studies, the Critical Appraisal Skills Program (CASP) was applied.

Results
The PEDro score of randomized studies ranged from 3 to 7 out of 10 (mean score=6), indicating a moderate methodological quality; there were 2 studies with low quality, 4 with moderate quality and 2 with high quality. The CASP score of the two cohort studies was 10 and 11 out of 12. Most studies had evaluated the effect of a preoperative ACL exercises program on the isokinetic strength of the knee. One study showed a significant difference in quadriceps strength between patients received preoperative ACL exercises (range of motion, strength and balance exercises) and those without preoperative exercises after surgery. In a study, a significant difference in maximum torque and quadriceps muscle function was observed in the intervention group that performed isokinetic strength training at 60-120 degrees per second for 4 weeks before surgery [25]. Logerstedt et al. examined the relationship between quadriceps strength before surgery and knee function after surgery. They found that quadriceps strength before surgery was a significant indicator of the International Knee Documentation Committee 2000 (IKDC 2000) score 6 months after surgery, and quadriceps weakness before surgery can affect the knee function after 6 months. Knee function was assessed using single-leg jump and a functional questionnaire. Three studies showed a significant difference between intervention and control groups. Kim et al. and Shaarani showed a significant increase in performance (during single-leg jump and using a functional questionnaire) in the intervention group who received preoperative exercise (range of motion, balance, and strength) compared to the controls. Filla et al. showed that in DOC University patients, there was a significant improvement in the IKDC 2000 and Knee Osteoarthritis outcome Score 2 years after surgery.

Discussion
The review of the studies showed that the groups that had received a preoperative exercise program showed a significant improvement in knee function and physical performance after surgery compared to the controls. It has been suggested that performing preoperative exercises (strength + neuromuscular) and achieving a normal range of motion, activating the quadriceps, reducing pain and swelling can lead to significant progress after two years of ACL reconstruction. Weakness in knee extensor strength after surgery is a common problem that has been reported in previous studies. The rapid decline in the function of the quadriceps, which occurs mainly in the early postoperative period, is caused by arthrogenic muscle inhibition due to pain, inflammation, swelling,

Inclusion Criteria Pico Indicators
Randomized controlled trial and cohort Design as well as impairment in the proprioceptors of the joint. This neurological mechanism for weakness of the quadriceps may persist for a long time after injury or ACL surgery.

Conclusion
Rehabilitation exercises before ACL reconstruction (neuromuscular and strength exercises) can increase knee function based on a single-leg jump test and functional questionnaire scores. It can increase the quadriceps strength in the short and long periods after surgery. Maximizing the strength of the quadriceps with advanced preoperative exercises should be a major goal for specialists to improve knee function after ACL surgery.

Compliance with ethical guidelines
This study is a systematic review and there is no need for ethical approve.

Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or notfor-profit sectors.

Conflicts of interest
The authors declare no conflict of interest.