title: Staged lengthening arthroplasty for pediatric osteosarcoma around the knee.
abstract: BACKGROUND
  Orthopaedic oncologists often must address leg-length discrepancy after resection of tumors in growing patients with osteosarcoma. There are various alternatives to address this problem. We describe a three-stage procedure: (1) temporary arthrodesis, (2) lengthening by Ilizarov apparatus, and (3) tumor prosthesis.
  
  
  OBJECTIVE
  We asked (1) to what extent are affected limbs actually lengthened; (2) how many of the patients who undergo a lengthening procedure eventually achieve joint arthroplasty; and (3) can the three-stage procedure give patients a functioning joint with equalization of limb length?
  
  
  METHODS
  We reviewed 56 patients (younger than 14 years) with osteosarcoma who had staged lengthening arthroplasty between 1991 and 2004.
  
  
  RESULTS
  Thirty-five of the 56 patients (63%) underwent soft tissue lengthening, and of these 35, 28 (50% of the original group of 56) had implantation of a mobile joint. Three of the 28 prostheses were later removed owing to infection after arthroplasty. The overall average length gained was 7.8 cm (range, 4-14 cm), and 25 (71%) of the 35 patients had a mobile joint at final followup. The average Musculoskeletal Tumor Society functional score was 23.2 (range, 15-28) and limb-length discrepancy at final followup was 2.6 cm (range, 0-6.5 cm). Although most mobile joints had an acceptable ROM (average, 74.2 degrees ; range, 35 degrees -110 degrees ), extension lag was frequent.
  
  
  CONCLUSIONS
  Our approach is one option for skeletally immature patients, especially in situations where an expandable prosthesis is not available. However, this technique requires multiple stages and would be inappropriate for patients who cannot accept prolonged functional deficit owing to a limited lifespan or other reasons.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopedic Surgery, Korea Cancer Center Hospital, 215-4 Gongneung-dong, Nowon-gu, Seoul 139-706, Korea.
authors.forename: Chang-Bae
authors.initials: CB
authors.lastname: Kong
authors.forename: Soo-Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Dae-Geun
authors.initials: DG
authors.lastname: Jeon
mesh_terms: D000293:Adolescent; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation; D001852:Bone Lengthening / Q000379:methods; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D002648:Child; D020878:Device Removal; D016267:External Fixators; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000254:growth & development / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis / Q000009:adverse effects; D007870:Leg Length Inequality / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D016459:Prosthesis-Related Infections / Q000209:etiology / Q000601:surgery; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012086:Reoperation; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome