How does iliosacral bone tumor resection without reconstruction affect the ipsilateral hip joint?

BACKGROUND: Whether reconstruction is more beneficial after iliosacral bone tumor resection remains controversial. Because of high rates of complications and recurrence, few patients benefit from reconstruction. The aim of this study is to assess functional outcomes and to reveal changes in the ipsilateral hip joint after partial iliosacral resection. METHODS: From 1998 to 2016, 21 patients aged 20–66 years underwent iliosacral resection, 18 without reconstruction (group 1) and 3 with reconstruction (group 2). Function was evaluated using the Musculoskeletal Tumor Society 1993 rating scale (MSTS 1993), and disability was measured using the Toronto Extremity Salvage Score (TESS). I-A distance was defined as the distance from the iliosacral joint to the upper line of the acetabulum along the curved line. Group 1 were subdivided into two groups: group 1A included the patients with a defect less than one-third of the I-A distance and group 1B the remainder. Acetabulum-head index (AHI) and center-edge angle (CE angle) were measured. The relationship between defect length and femoral head coverage was analyzed. RESULTS: The mean follow-up was 67.3 months. Eighteen patients were included in group 1 and three in group 2. Preoperative data of the 3 groups were statistically equivalent. In addition, no difference of postoperative functional outcome has been highlighted. The final average MSTS 1993 score was 93.6% in group 1 and 93.3% in group 2. The mean TESS was 98 in group 1 and 98.5 in group 2. AHI and CE angle between groups 1 and 2 were not different. The AHI was 80 ± 5.4% in group 1A and 67 ± 9.0% in group 1B (t = − 3.740, P = 0.002), while the CE angle was 29 ± 5.9° in group 1A and 20 ± 6.3° in group 1B (t = − 3.172, P = 0.006) at the last follow-up. Regarding the limb-length discrepancy, group 1 and 2 were similar whereas group 1A and 1B were statistically different (group 1A: 0.7 ± 0.7 cm; group 2: 2.6 ± 1.0 cm; t = − 4.324, P = 0.001). CONCLUSIONS: Ilio-sacral resection without reconstruction removing more than one- third of the I-A distance leads to an impairement of the limb-length discrepancy and an increase of the defect of the acetabular coverage without altering the functional outcome. Nevertheless, iliosacral resection without reconstruction could serve as a viable treatment option for pelvic type I-IV tumors.