title: Quadriceps muscle weakness after anterior cruciate ligament reconstruction: a risk factor for knee osteoarthritis?
abstract: OBJECTIVE
  To identify risk factors for knee osteoarthritis (OA) 10-15 years after anterior cruciate ligament (ACL) reconstruction. We hypothesized that quadriceps muscle weakness after ACL reconstruction would be a risk factor for radiographic and symptomatic radiographic knee OA 10-15 years later.
  
  
  METHODS
  Subjects with ACL reconstruction (n=258) were followed for 10-15 years. Subjects with unilateral injury at the 10-15-year followup were included in the present study. Outcomes included the Cincinnati knee score, knee joint laxity, hop performance, and isokinetic muscle strength tests at 6 months, 1 year, and 2 years postoperatively. At the 10-15-year followup, radiographs were taken and graded according to the Kellgren/Lawrence classification (range 0-4).
  
  
  RESULTS
  Of the 212 subjects (82%) assessed at the 10-15-year followup, 164 subjects had unilateral injury. The mean±SD age at ACL reconstruction was 27.4±8.5 years. Increased age (odds ratio [OR] 1.06, 95% confidence interval [95% CI] 1.01-1.11) and meniscal injury and/or chondral lesion (OR 2.05, 95% CI 1.00-4.20) showed significantly higher odds for radiographic knee OA. Low self-reported knee function 2 years postoperatively (OR 0.95, 95% CI 0.92-0.98) and loss of quadriceps strength between the 2-year and the 10-15-year followup (OR 1.00, 95% CI 1.00-1.01) showed significantly higher odds for symptomatic radiographic knee OA. Quadriceps muscle weakness after ACL reconstruction was not significantly associated with knee OA.
  
  
  CONCLUSIONS
  This study detected no association between quadriceps weakness after ACL reconstruction and knee OA as measured 10-15 years later.
authors.affiliation: Norwegian Research Centre for Active Rehabilitation and Oslo University Hospital and Ullevaal, Oslo, Norway. oiestad@hotmail.com
authors.forename: Britt Elin
authors.initials: BE
authors.lastname: Øiestad
authors.forename: Inger
authors.initials: I
authors.lastname: Holm
authors.forename: Ragnhild
authors.initials: R
authors.lastname: Gunderson
authors.forename: Grethe
authors.initials: G
authors.lastname: Myklebust
authors.forename: May Arna
authors.initials: MA
authors.lastname: Risberg
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D007718:Knee Injuries / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D018908:Muscle Weakness / Q000150:complications / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D011379:Prognosis; D052097:Quadriceps Muscle / Q000503:physiopathology*; D011859:Radiography; D019651:Plastic Surgery Procedures / Q000009:adverse effects*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors