title: [Clinical observation on extensor weakness after total knee arthroplasty for severe flexion deformity knees].
abstract: OBJECTIVE
  To find out the reasons of extensor weakness after total knee arthroplasty for severe flexion deformity knees, and the rehabilitation method.
  
  
  METHODS
  From January 2001 to January 2004, 30 knees (20 cases) with severe flexion deformity were performed total knee arthroplasty with PS prosthesis, and the follow up were at least 6 months (6 to 40 months, average 18 months). All cases in this group were classified with the extensor force grade and were given certain exercises according to the grade. The HSS scores, extensor force, residual flexion deformity, satisfaction scores and rang of motion were recorded pre-operation and 3 days, 2 weeks, 4 weeks, 8 weeks, 12 weeks, 6 months and then every year when follow up.
  
  
  RESULTS
  At the end point of the 6 months follow up, all items increased significantly, the average HSS score was 75.9 degrees, the average extensor force was 4.1, 8 knees among the group remained an average flexion deformity with 7.4 degrees, all patients were satisfied with the operation, and the average range of motion was 87.7 degrees.
  
  
  CONCLUSIONS
  Quadriceps atrophy for disuse and the relative extensor mechanism excess are the main cause of extensor deficit, correct strength evaluation and individual exercise project are critical principle for successful rehabilitation.
authors.affiliation: Department of Orthopaedics, Guanghua Hospital, Shanghai 200052, China.
authors.forename: Guo-zhang
authors.initials: GZ
authors.lastname: Feng
authors.forename: Hao
authors.initials: H
authors.lastname: Dai
authors.forename: Yong
authors.initials: Y
authors.lastname: He
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016916:Joint Deformities, Acquired / Q000601:surgery*; D007719:Knee Joint / Q000002:abnormalities* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology / Q000534:rehabilitation*; D011183:Postoperative Complications / Q000534:rehabilitation*