title: Is It Possible and Safe to Perform Acetabular-preserving Resections for Malignant Neoplasms of the Periacetabular Region?
abstract: BACKGROUND
  Primary malignant tumors located near the acetabulum are usually managed by resection of the tumor with wide margins that include the acetabulum. These resections are deemed P2 resections by the Enneking and Dunham classification. There are various methods to perform the subsequent hip reconstruction. Unfortunately, there is no consensus as to the best management. In general, patients undergoing resection at this level will have substantial levels of pain and disability as measured by the Musculoskeletal Tumor Society (MSTS) scoring system. We believe there is a subset of patients whose tumors in this location can be resected while preserving all or most of the weightbearing acetabulum using navigation and careful surgical planning.
  
  
  OBJECTIVE
  (1) What complications were associated with this resection; (2) what oncological outcomes (histological margins and local recurrence) were achieved; and (3) what is the function achieved by these patients?
  
  
  METHODS
  This was a retrospective study of patients with periacetabular primary malignancy. From 2008 to 2014, we treated 12 patients who had periacetabular primary malignant tumors and in five, we performed resection with the weightbearing portion spared. During this period, our general indications to perform a resection that spared the acetabulum were the tumor with its resection margin not involving the weightbearing portion of the acetabulum. However, we did not perform this procedure in patients who had more cranial lesion involving the weightbearing portion or whose hip stability might be in question after the tumor excision. Three patients were women and the other two were men. Four were chondrosarcomas, whereas the other one was synovial sarcoma. Ages ranged from 46 to 60 years (average, 53 years). Minimum followup was 14 months (median, 37 months; range, 14-88 months); no patients were lost to followup before a 1-year minimum was achieved, and all patients have been seen within the last 9 months.
  
  
  RESULTS
  There were no intraoperative or early postoperative complications. None of the five patients had a positive margin by histological assessment. No local recurrences were detected. The median functional score by MSTS was 28 out of 30 (range, 27-30).
  
  
  CONCLUSIONS
  The roof of the acetabulum is the weightbearing portion of the acetabulum. It also maintains the stability of the hip. With precise preoperative planning of the resection and accurate execution of the procedure, the hip-sparing approach through partial acetabular resection can be performed in selected patients with malignant periacetabular neoplasms. Navigation makes it possible to minimize the amount of bone resection. In this preliminary report of a small number of patients, we had adequate short-term local tumor control. We believe the function is good, but we do not have a comparison group of patients to document improved function.
  
  
  METHODS
  Level IV, therapeutic study.
authors.affiliation: Queen Mary Hospital, Hong Kong SAR, China. albertlam2000@yahoo.com.|Department of Orthopaedics and Traumatology, Queen Mary Hospital, 5th Floor, Professorial Block, 102 Pok Fu Lam Road, Hong Kong SAR, China. albertlam2000@yahoo.com.
authors.forename: Ying-Lee
authors.initials: YL
authors.lastname: Lam
authors.affiliation: Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: Raymond
authors.initials: R
authors.lastname: Yau
authors.affiliation: Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: Kenneth W Y
authors.initials: KW
authors.lastname: Ho
authors.affiliation: Queen Elizabeth Hospital, Hong Kong SAR, China.
authors.forename: Ka-Lok
authors.initials: KL
authors.lastname: Mak
authors.affiliation: Queen Elizabeth Hospital, Hong Kong SAR, China.
authors.forename: Sin-Tak
authors.initials: ST
authors.lastname: Fong
authors.affiliation: Queen Elizabeth Hospital, Hong Kong SAR, China.
authors.forename: Timothy Y C
authors.initials: TY
authors.lastname: So
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D059925:Anatomic Landmarks; D001696:Biomechanical Phenomena; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D000072662:Margins of Excision; D008875:Middle Aged; D008953:Models, Anatomic; D010027:Osteotomy / Q000009:adverse effects / Q000379:methods*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000209:etiology; D018579:Patient Selection; D010386:Pelvic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D016474:Weight-Bearing