Muscle Strength and Functional Performance in Patients With Anterior Cruciate Ligament Injury Treated With Training and Surgical Reconstruction or Training Only: A Two to Five-Year Followup EVA AGEBERG, 1 ROLAND THOMEE ´ , 2 CAMILLE NEETER, 2 KARIN GRA ¨ VARE SILBERNAGEL, 2 AND EWA M. ROOS 3 Objective. To study muscle strength and functional performance in patients with anterior cruciate ligament (ACL) injury with or without surgical reconstruction 2 to 5 years after injury. Good muscle function is important in preventing early-onset osteoarthritis (OA), but the role of reconstructive surgery in restoring muscle function is unclear. Methods. Of 121 patients with ACL injury included in a randomized controlled trial on training and surgical recon- struction versus training only (the Knee, Anterior cruciate ligament, NON-surgical versus surgical treatment [KANON] study, ISRCTN: 84752559), 54 (mean age at followup 30 years, range 20 –39, 28% women) were assessed a mean  SD of 3  0.9 years after injury with reliable, valid, and responsive test batteries for strength (knee extension, knee flexion, leg press) and hop performance (vertical jump, one-leg hop, side hop). The Limb Symmetry Index (LSI; injured leg divided by uninjured and multiplied by 100) value and absolute values were used for comparisons between groups (analysis of variance). An LSI >90% was considered normal. Results. There were no differences between the surgical and nonsurgical treatment groups in muscle strength or functional performance. Between 44% and 89% of subjects had normal muscle function in the single tests, and between 44% and 56% had normal function in the test batteries. Conclusion. The lack of differences between patients treated with training and surgical reconstruction or training only indicates that reconstructive surgery is not a prerequisite for restoring muscle function. Abnormal muscle function, found in approximately one-third or more of the patients, may be a predictor of future knee OA. INTRODUCTION Anterior cruciate ligament (ACL) injuries are associated with the development of osteoarthritis (OA) in the long term, leading to pain, functional limitations, and decline in quality of life in the young or middle-aged adult (1,2). There is no evidence to suggest that reconstruction of the ACL prevents or reduces the rate of early-onset OA (2). On the contrary, the prevalence of OA may be even higher in patients with reconstructed ACL than in those with non- reconstructed ACL (3,4). Despite these long-term conse- quences, surgical treatment is widely used (5) and 50% of patients in Sweden and 90% of patients in the US with ACL deficiency have surgical reconstruction. It has been suggested that neuromuscular function is of importance for the overall outcome after injury (6) and in preventing OA (1,7,8). Longitudinal, prospective studies Supported by the Swedish National Centre for Research in Sports, the Swedish Research Council, the Swedish Rheu- matism Association, Region Skåne, the Local Research and Development Council of Go ¨ teborg and Southern Bohusla ¨n, and the Faculty of Medicine, Lund University. The original KANON study, from which the patients were included, was additionally supported by Pfizer Global Research, Thelma Zoegas Fund, the Swedish National Centre for Research in Sports, and the Stig & Ragna Gorthon Research Fund. 1 Eva Ageberg, PT, PhD: Clinical Sciences Lund, Lund University, Lund, Sweden; 2 Roland Thomee ´, PT, PhD, Camille Neeter, PT, PhD, Karin Gra ¨ vare Silbernagel, PT, ATC, PhD: Lundberg Laboratory of Orthopaedic Research, Go ¨ teborg University, Gothenburg, Sweden; 3 Ewa M. Roos, PT, PhD: Clinical Sciences Lund, Lund University, Lund, Sweden, and Institute of Sports Science and Clinical Bio- mechanics, University of Southern Denmark, Odense, Denmark. Address correspondence to Eva Ageberg, PT, PhD, Depart- ment of Orthopedics, Clinical Sciences Lund, Lund Univer- sity, Lund University Hospital, SE-221 85 Lund, Sweden. E-mail: eva.ageberg@med.lu.se. Submitted for publication January 24, 2008; accepted in revised form July 9, 2008. Arthritis & Rheumatism (Arthritis Care & Research) Vol. 59, No. 12, December 15, 2008, pp 1773–1779 DOI 10.1002/art.24066 © 2008, American College of Rheumatology ORIGINAL ARTICLE 1773