title: Boomerang proximal tibial osteotomy for the treatment of severe varus gonarthrosis.
abstract: OBJECTIVE
  The purpose of the study was to review the results of modified infratubercle displacement osteotomy in patients with severe varus gonarthrosis and to determine the factors influencing outcomes.
  
  
  METHODS
  A total of 177 knees in 133 patients with severe varus gonarthrosis were treated with infratubercle boomerang-shaped osteotomy, stabilised with dual plates. The mean age of the patients was 63.8 years (range 43-80 years), and the mean follow-up period was 61.4 months (range 24 -139 months). The factors associated with clinical and survival outcomes were analysed including age, gender, body mass index (BMI), preoperative and post-operative femorotibial angle and femorotibial angle at one year after surgery.
  
  
  RESULTS
  Using the Knee Society clinical rating system 149 knees or 84.2 % were rated as having good to excellent results and 21 knees or 15.8 % as having fair to poor results. Overall, the mean preoperative knee score of 33.6 points had improved significantly to 80.7 points at the final follow-up (p < 0.001). Using Kaplan-Meier survivorship analysis the five-year survival was 97.1 % with conversion to arthroplasty or second osteotomy as the end point and 89.2 % with a knee score of under 70 points as the end point. The anatomical femorotibial angle at one year after osteotomy had the most significant positive effect on the clinical (p < 0.001) and survival outcomes for all end points (p = 0.002 for conversion to arthroplasty or second osteotomy and p < 0.001 for knee score less than 70 points).
  
  
  CONCLUSIONS
  The boomerang osteotomy can create adequate valgus alignment in severe varus gonarthrosis. The one-year post-operative knee alignment of 11° valgus provided the most satisfactory results and that between six and 15° valgus the longest survival time.
authors: Orthopaedics, Police General Hospital, Bangkok, Thailand. chanchits@gmail.com
authors: Chanchit
authors: C
authors: Sangkaew
authors: Peerapong
authors: P
authors: Piyapittayanun
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017760:Bone Malalignment / Q000000981:diagnostic imaging / Q000601:surgery*; D001860:Bone Plates; D001863:Bone Screws; D005260:Female; D005269:Femur / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators; D016916:Joint Deformities, Acquired / Q000000981:diagnostic imaging / Q000601:surgery*; D053208:Kaplan-Meier Estimate; D007719:Knee Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013977:Tibia / Q000002:abnormalities / Q000601:surgery*; D016896:Treatment Outcome
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