title: Correlation between range of motion and outcome after lumbar total disc replacement: 8.6-year follow-up.
abstract: METHODS
  Retrospective radiographic and chart review.
  
  
  OBJECTIVE
  To examine the relationship between lumbar total disc replacement (TDR) range of motion (ROM) and clinical outcome at 8.6-year follow-up.
  
  
  BACKGROUND
  There are no studies on the relationship between TDR motion and clinical outcomes.
  
  
  METHODS
  We reviewed 38 patients who underwent 1 or 2-level TDR implantation with 51 TDR. Flexion-extension ROM was measured on lateral radiographs. Clinical outcomes were measured at 8.6 years by modified Stauffer-Coventry scores, Oswestry Disability Questionnaires (ODQ), and subjective ratings of back pain, leg pain, and disability. Spearman rank correlation coefficient was used to determine if ROM was correlated with clinical outcome. Patients were divided into 2 groups by motion (< or = 5 degrees and > 5 degrees ). Statistical differences in outcome were sought.
  
  
  RESULTS
  Spearman rank correlation coefficient revealed weak-to-moderate but statistically significant associations between ROM and outcome for postoperative back pain (r = -0.35, P = 0.034), ODQ (r = -0.33, P = 0.046), and modified Stauffer-Coventry scores (r = 0.42, P = 0.0095). Patients with motion of > 5 degrees had superior outcomes in ODQ (mean difference 12.6 points, P = 0.026) and Stauffer-Coventry scores (mean difference 2.2 points, P = 0.015).
  
  
  CONCLUSIONS
  The radiographic ROM at 8.6-year follow-up was positively correlated with several outcomes measures. Patients with motion > 5 degrees had clinically modest but statistically better outcomes in ODQ and modifiedStauffer-Coventry scores. Longer follow-ups will be necessary to measure fully the impact of TDR ROM on outcome.
authors.affiliation: Spine Surgery Service, Hospital for Special Surgery, New York, NY 10021, USA. russelhuang@yahoo.com
authors.forename: Russel C
authors.initials: RC
authors.lastname: Huang
authors.forename: Federico P
authors.initials: FP
authors.lastname: Girardi
authors.forename: Frank P
authors.initials: FP
authors.lastname: Cammisa
authors.forename: Moe R
authors.initials: MR
authors.lastname: Lim
authors.forename: Patrick
authors.initials: P
authors.lastname: Tropiano
authors.forename: Thierry
authors.initials: T
authors.lastname: Marnay
mesh_terms: D000328:Adult; D000368:Aged; D019643:Arthroplasty, Replacement / Q000379:methods*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology / Q000601:surgery*; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D017116:Low Back Pain / Q000209:etiology / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009068:Movement; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D016896:Treatment Outcome