Quadriceps muscle activation and radiographic osteoarthritis following ACL revision.
OBJECTIVE
Quadriceps strength and activation may play an important role in the recovery from ACL revision surgery. The purpose of this study was to describe quadriceps strength and central activation ratio (CAR) and correlate with radiographic findings in patients with ACL revision surgery.


METHODS
Twenty-one patients who were on average 47.5 ± 21.1 months [range: 14-85 months] post-revision ACL reconstruction. We performed knee joint physical examination and radiographic evaluation. Quadriceps strength testing consisted of maximal voluntary isometric contractions (MVIC) with the knee bent to 90-degrees bilaterally. We calculated quadriceps central activation ratio using the superimposed burst technique. Radiographs (bilateral standing antero-posterior in knee flexion and lateral in full extension) were evaluated by a fellowship-trained orthopedic surgeon using the International Knee Documentation Committee (IKDC) grading system.


RESULTS
Mean CAR was 83.9 ± 12.0% on the reconstructed limb and 85.5 ± 9.5% on the contralateral limb. Average, normalized MVIC torque was 2.5 ± 1.0 Nm/kg on the reconstructed limb and 2.7 ± 1.0 N m/kg for the contralateral limb. Patient age at the time of follow-up evaluation was related to severity of knee joint degeneration, particularly the medial, anterior and patellofemoral compartments. Younger patients with lower CARs tended to have more severe degeneration in the patellofemoral joint. Older patients with lower normalized MVIC torque values tended to exhibit more severely graded degeneration in the patellofemoral joint.


CONCLUSIONS
Bilateral quadriceps central activation deficits and radiographic osteoarthritis are evident in patients with revision ACL reconstruction.
Department of Orthopaedic Surgery, University of Virginia, 400 Ray C. Hunt Drive, Suite 330, PO Box 800159, Charlottesville, VA 22908, USA. jmh3zf@virginia.edu
Joseph M
JM
Hart
Kimberly A
KA
Turman
David R
DR
Diduch
Jennifer A
JA
Hart
Mark D
MD
Miller
D000328:Adult; D000367:Age Factors; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D015331:Cohort Studies; D004599:Electric Stimulation Therapy / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D007537:Isometric Contraction; D007718:Knee Injuries / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D018908:Muscle Weakness / Q000209:etiology / Q000534:rehabilitation*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D010808:Physical Examination / Q000379:methods; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D011859:Radiography; D019651:Plastic Surgery Procedures / Q000009:adverse effects* / Q000379:methods; D012086:Reoperation; D018570:Risk Assessment; D012737:Sex Factors; D013997:Time Factors; D055815:Young Adult