Improvement of Outcomes With Nonconcurrent Strength and Cardiovascular-Endurance Rehabilitation Conditioning After ACI Surgery to the Knee

in Journal of Sport Rehabilitation
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Autologous chondrocyte implantation (ACI) aims to restore hyaline cartilage. Traditionally, ACI rehabilitation is prescribed in a concurrent (CON) format. However, it is well known from studies in asymptomatic populations that CON training produces an interference effect that can attenuate strength gains. Strength is integral to joint function, so adopting a nonconcurrent (N-CON) approach to ACI rehabilitation might improve outcomes.


To assess changes in function and neuromuscular performance during 48 wk of CON and N-CON physical rehabilitation after ACI to the knee.


Orthopedic Hospital NHS Foundation Trust.


Randomized control, pilot study.


11 patients (9 male, 2 female; age 32.3 ± 6.6 y; body mass 79.3 ±10.4 kg; time from injury to surgery 7.1 ± 4.9 mo [mean ± SD]) randomly allocated to N-CON:CON (2:1).


Standardized CON and N-CON physiotherapy that involved separation of strength and cardiovascular-endurance conditioning.

Main Outcome Measures:

Function in the single-leg-hop test, patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score [KOOS], International Knee Documentation Committee subjective questionnaire [IKDC]), and neuromuscular outcomes of peak force (PF), rate of force development (RFD), electromechanical delay (EMD), and sensorimotor performance (force error [FE]) of the knee extensors and flexors of the injured and noninjured legs, measured presurgery and at 6, 12, 24, and 48 wk postsurgery.


Factorial ANOVAs with repeated measures of group by leg and by test occasion revealed significantly superior improvements for KOOS, IKDC, PF, EMD, and FE associated with N-CON vs CON rehabilitation (F1.5,13.4 GG = 3.7−4.7, P < .05). These results confirm increased peak effectiveness of N-CON rehabilitation (~4.5−13.3% better than CON over 48 wk of rehabilitation). N-CON and CON showed similar patterns of improvement for single-leg-hop test and RFD.


Nonconcurrent strength and cardiovascular-endurance conditioning during 48 wk of rehabilitation after ACI surgery elicited significantly greater improvements to functional and neuromuscular outcomes than did contemporary concurrent rehabilitation.

Bailey is with the Dept of Physiotherapy, and Richardson, the Inst of Orthopaedics, RJAH Orthopaedic NHS Foundation Trust, Oswestry, UK. Minshull is with the School of Health Sciences, Queen Margaret University Edinburgh, Edinburgh, UK. Gleeson is with the School of Health Sciences, Queen Margaret University Edinburgh, Edinburgh, UK. Address author correspondence to Andrea Bailey at