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V. Korakakis1,2, R. Kotsifaki2, R. Whiteley2, A. Bjerregaard3
1King's College London, Department of Population Health Sciences, Physiotherapy Education, London, United Kingdom, 2Aspetar, Orthopaedic and Sports Medicine Hospital, Rehabilitation Department, Doha, Qatar, 3Aspetar, Sports Medicine Hopsital, Department of Rehabilitation, Doha, Qatar
Background: An essential priority in rehabilitation after anterior cruciate ligament reconstruction (ACLR) is the restoration of knee muscle strength. However, longitudinal data of the knee strength milestones that patients and clinicians aim in the course of ACLR rehabilitation is sparse.
Purpose: To describe the knee muscle strength (quadriceps and hamstrings) up to 9 months after ACLR of an uncomplicated rehabilitation course, categorized into level of activity and graft type (bone-patellar tendon-bone – BPTB, hamstring – HS).
Methods: 392 professional and recreational athletes (age 26.2±6.7 years) underwent a supervised rehabilitation after ACLR. To assess the knee strength progress during an uncomplicated rehabilitation course, we excluded patients with pain and complications that hampered rehabilitation (>6 weeks) and resulted in a muscle strength decline exceeding 15% for two consecutive assessments.
Concentric peak strength (60°/sec) measurements of the knee joint muscles (adjusted to body weight-BW) were performed using an isokinetic dynamometer at five time-points (3, 4.5, 6, 7.5, and 9 months) following ACLR. Data was analyzed using mixed-effects models and participant specific random effects. Fixed effects included graft type, athlete categorization, time of strength assessment, and all interactions. We modelled the parameter estimates for covariates associated with recovery after applying Tukey adjustment for multiple comparisons.
Concentric peak strength (60°/sec) measurements of the knee joint muscles (adjusted to body weight-BW) were performed using an isokinetic dynamometer at five time-points (3, 4.5, 6, 7.5, and 9 months) following ACLR. Data was analyzed using mixed-effects models and participant specific random effects. Fixed effects included graft type, athlete categorization, time of strength assessment, and all interactions. We modelled the parameter estimates for covariates associated with recovery after applying Tukey adjustment for multiple comparisons.
Results: Professional athletes with a HS graft displayed significantly greater quadriceps strength than recreational with BPTB graft at all time-points of evaluation (except 7.5m, p=0.3627). No other significant differences were found between activity level and graft type.
Professional and recreational athletes’ quadriceps strength significantly (p<0.001, p<0.01 respectively) increased through time (irrespective of graft type). Professionals with HS graft reached maximum quadriceps strength (>2.5 times BW) at 6-months, and recreationals (>2.3 times BW) at 7.5-months post operatively.
Professional athletes with a BPTB graft displayed greater hamstring strength at all time-points of evaluation than all the other groups, while professionals with a HS graft had stronger hamstrings than the recreationals with a HS graft throughout rehabilitation (except 7.5m).
Professional athletes showed significantly (p<0.05) greater hamstring strength through time (irrespective of graft type). Both athletic categories reached maximum hamstring strength at 6-months post operatively (>1.7 and >1.5 times BW, for BPTB and HS).
Recreational athletes with a BPTB graft displayed a significant increase in hamstring strength within 4.5 months post-ACLR (1.4 times BW) and remained stable during rehabilitation. Conversely, hamstring strength of the recreational athletes with a HS graft was consistently improving up to 7.5 months postoperatively where it reached 1.4 times BW.
Professional and recreational athletes’ quadriceps strength significantly (p<0.001, p<0.01 respectively) increased through time (irrespective of graft type). Professionals with HS graft reached maximum quadriceps strength (>2.5 times BW) at 6-months, and recreationals (>2.3 times BW) at 7.5-months post operatively.
Professional athletes with a BPTB graft displayed greater hamstring strength at all time-points of evaluation than all the other groups, while professionals with a HS graft had stronger hamstrings than the recreationals with a HS graft throughout rehabilitation (except 7.5m).
Professional athletes showed significantly (p<0.05) greater hamstring strength through time (irrespective of graft type). Both athletic categories reached maximum hamstring strength at 6-months post operatively (>1.7 and >1.5 times BW, for BPTB and HS).
Recreational athletes with a BPTB graft displayed a significant increase in hamstring strength within 4.5 months post-ACLR (1.4 times BW) and remained stable during rehabilitation. Conversely, hamstring strength of the recreational athletes with a HS graft was consistently improving up to 7.5 months postoperatively where it reached 1.4 times BW.
Conclusions: Knee strength increases during rehabilitation but at the initial phase of ACLR rehabilitation is influenced by the graft type, while at the end of rehabilitation it is affected by the activity level. The maximum achieved strength is affected mostly by activity level.
Implications: The presented knee strength evolution data may be useful in interpreting the effectiveness of the treatment, in tracking the normal trajectory of the rehabilitation process, and informing the clinical reasoning and decision-making on the ACLR management choices.
Funding acknowledgements: None declared
Keywords:
Anterior Cruciate Ligament (ACL)
Strength
Quadriceps
Anterior Cruciate Ligament (ACL)
Strength
Quadriceps
Topics:
Musculoskeletal: lower limb
Sport & sports injuries
Musculoskeletal: lower limb
Sport & sports injuries
Did this work require ethics approval? Yes
Institution: Aspetar, Orthopaedic and Sports Medicine Hospital
Committee: Aspire Zone Foundation - IRB
Ethics number: F2017000227
All authors, affiliations and abstracts have been published as submitted.
