Lower Extremity Performance Following ACL Rehabilitation
Background The additional effect of anterior cruciate ligament (ACL) reconstruction on muscle strength and physical performance after a structured exercise programme is not well understood.
Objectives To investigate and compare muscle strength and physical performance test results after a structured exercise programme, in young active adults with acute ACL injury, between those treated with and without ACL reconstruction (ACLR) and to evaluate these test results as predictors of clinical outcomes 2 and 5 years after injury.
Study design Prospective cohort study.
Methods In a treatment randomised controlled trial of acute ACL injury (the KANON-study), 87/121 young active adults underwent two muscle strength tests and five physical performance tests after a structured exercise programme (median 37 (IQR 24) weeks after injury). Results were presented and compared as limb symmetry indices (LSI); endpoints in predictive analyses were having a delayed ACLR over the first 5 years and self-reported knee function (Knee injury and Osteoarthritis Outcome Score; KOOS4) at 2 and 5 years.
Results Overall, 74–95% of patients had LSI≥90% in the individual tests, with no difference between treatment groups (p=0.08–0.92). Results of the one-leg rise tests predicted KOOS4 at 2 and 5 years (R=0.25 and 0.24, p=0.001 and 0.002) and vertical hop results predicted having a delayed ACLR over a 5-year course after injury (p=0.048) in those starting with exercise alone (n=21).
Conclusions After an acute ACL tear, the majority of young active adults regain physical performance and muscle strength after a structured exercise programme, with or without surgical reconstruction. Poor physical performance at the end of rehabilitation predicted worse patient-reported outcomes at 2 and 5 years regardless of treatment.
Rupture of the anterior cruciate ligament (ACL) may cause long-lasting functional impairment and knee osteoarthritis (OA). Optimal treatment after acute ACL injury is debated. A recent randomised controlled trial (RCT) failed to show any clinically significant difference in self-reported knee function, physical activity level and the frequency of radiographic knee OA 2 and 5 years after acute ACL injury between young active adults treated with and without ACL reconstruction (ACLR).
ACLR aims to restore the mechanical stability of the injured knee, whereas a structured exercise programme aims to restore knee function; it is an essential part of treatment whether patients undergo knee reconstruction or not. Physical performance testing is usually performed to determine if and when the patient may resume sports but there is no consensus on which specific physical performance tests to use in the ACL injured patient. Tests of muscle strength and endurance, balance and muscle power are commonly employed in combination. The use of a test battery, including two or more hop tests, has been recommended to assess different aspects of muscle function after ACL injury and reconstruction. Test results are often expressed as limb symmetry index (LSI, injured leg divided by uninjured leg results×100), and satisfactory muscular function is usually defined as an LSI≥90%.
Few studies have compared physical performance of ACL-injured patients treated with and without ACLR. Consequently, the added benefit of ACLR on physical performance remains to be determined. One year after ACL injury, Moksnes and Risberg found that non-operated patients performed better than operated patients in two of four single-legged hop tests. Two independent reports found that hop test results obtained during the early phase of a structured exercise programme after ACL injury could predict self-reported outcome after 1 year in both ACL-reconstructed and in non-reconstructed patients. However, data from high-quality randomised trials are lacking. Early identification of factors that could predict later need of ACLR and longer term self-reported knee function may be important.
Using data from a treatment RCT on acute ACL injury (the KANON study, ISRCTN84752559), we aimed to (1) compare results of muscle strength and physical performance testing, performed at the end of the exercise period, between patients treated with and without ACLR, (2) evaluate muscle strength and physical performance test results as predictors of self-reported outcome at 2 and 5 years after injury and (3) explore whether muscle strength and physical performance test results predicted the future need of ACLR in those starting with exercise alone.
Abstract and Introduction
Abstract
Background The additional effect of anterior cruciate ligament (ACL) reconstruction on muscle strength and physical performance after a structured exercise programme is not well understood.
Objectives To investigate and compare muscle strength and physical performance test results after a structured exercise programme, in young active adults with acute ACL injury, between those treated with and without ACL reconstruction (ACLR) and to evaluate these test results as predictors of clinical outcomes 2 and 5 years after injury.
Study design Prospective cohort study.
Methods In a treatment randomised controlled trial of acute ACL injury (the KANON-study), 87/121 young active adults underwent two muscle strength tests and five physical performance tests after a structured exercise programme (median 37 (IQR 24) weeks after injury). Results were presented and compared as limb symmetry indices (LSI); endpoints in predictive analyses were having a delayed ACLR over the first 5 years and self-reported knee function (Knee injury and Osteoarthritis Outcome Score; KOOS4) at 2 and 5 years.
Results Overall, 74–95% of patients had LSI≥90% in the individual tests, with no difference between treatment groups (p=0.08–0.92). Results of the one-leg rise tests predicted KOOS4 at 2 and 5 years (R=0.25 and 0.24, p=0.001 and 0.002) and vertical hop results predicted having a delayed ACLR over a 5-year course after injury (p=0.048) in those starting with exercise alone (n=21).
Conclusions After an acute ACL tear, the majority of young active adults regain physical performance and muscle strength after a structured exercise programme, with or without surgical reconstruction. Poor physical performance at the end of rehabilitation predicted worse patient-reported outcomes at 2 and 5 years regardless of treatment.
Introduction
Rupture of the anterior cruciate ligament (ACL) may cause long-lasting functional impairment and knee osteoarthritis (OA). Optimal treatment after acute ACL injury is debated. A recent randomised controlled trial (RCT) failed to show any clinically significant difference in self-reported knee function, physical activity level and the frequency of radiographic knee OA 2 and 5 years after acute ACL injury between young active adults treated with and without ACL reconstruction (ACLR).
ACLR aims to restore the mechanical stability of the injured knee, whereas a structured exercise programme aims to restore knee function; it is an essential part of treatment whether patients undergo knee reconstruction or not. Physical performance testing is usually performed to determine if and when the patient may resume sports but there is no consensus on which specific physical performance tests to use in the ACL injured patient. Tests of muscle strength and endurance, balance and muscle power are commonly employed in combination. The use of a test battery, including two or more hop tests, has been recommended to assess different aspects of muscle function after ACL injury and reconstruction. Test results are often expressed as limb symmetry index (LSI, injured leg divided by uninjured leg results×100), and satisfactory muscular function is usually defined as an LSI≥90%.
Few studies have compared physical performance of ACL-injured patients treated with and without ACLR. Consequently, the added benefit of ACLR on physical performance remains to be determined. One year after ACL injury, Moksnes and Risberg found that non-operated patients performed better than operated patients in two of four single-legged hop tests. Two independent reports found that hop test results obtained during the early phase of a structured exercise programme after ACL injury could predict self-reported outcome after 1 year in both ACL-reconstructed and in non-reconstructed patients. However, data from high-quality randomised trials are lacking. Early identification of factors that could predict later need of ACLR and longer term self-reported knee function may be important.
Using data from a treatment RCT on acute ACL injury (the KANON study, ISRCTN84752559), we aimed to (1) compare results of muscle strength and physical performance testing, performed at the end of the exercise period, between patients treated with and without ACLR, (2) evaluate muscle strength and physical performance test results as predictors of self-reported outcome at 2 and 5 years after injury and (3) explore whether muscle strength and physical performance test results predicted the future need of ACLR in those starting with exercise alone.
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