(P 295) PERIACETABULAR INTERNAL HEMIPELVECTOMY WITH AND WITHOUT SACRAL RESECTION: AN INSTITUTIONAL EXPERIENCE AND SYSTEMATIC REVIEW

Objective: Internal hemipelvectomy is a limb sparing procedure most commonly indicated for malignant bone and soft tissue tumors of the pelvis. Partial resection and pelvic reconstruction may be challenging for orthopedic oncologists due to late presentation, high tumor burden, and complex anatomy. Specifically, wide resection of tumors involving the periacetabular and sacroiliac (SI) regions may compromise adjacent vital neurovascular structures, impair wound healing, or limit functional recovery. Moreover, since implants are commonly fixed to the sacrum, concomitant sacral resection reduces viable bone stock for fixation, and can compromise construct strength and generate lumbosacral instability.

The purpose of this study was to present and evaluate a series of patients treated at a single institution who underwent periacetabular internal hemipelvectomy (Type II) with or without sacral extension (Type IV). To validate these findings, we systematically reviewed existing literature to investigate postoperative complications, functional outcomes, and implant and patient survival following pelvic tumor resection via Type II hemipelvectomy with or without Type IV resection.

Methods: We retrospectively reviewed a surgical registry at a single institution of consecutive patients from 1994 to 2000 treated with internal hemipelvectomy for primary or secondary pelvic bone tumors. All type II resection patients were stratified into two separate cohorts based on whether or not periacetabular resection was extended beyond the SI joint to include the sacrum (Type IV), as per Enneking and Dunham classification. Patient demographics, operative parameters, complications, and oncological outcomes were collected. Categorical and continuous variables were compared with Pearson’s chi square or Fisher’s exact test and the Mann-Whitney U-test, respectively. Literature review according to PRISMA guidelines queried studies pertaining to patient outcomes following periacetabular internal hemipelvectomy.

Results: A total of 76 patients were treated at a single institution with internal hemipelvectomy for pelvic tumor resection, of whom 21 had periacetabular resection. Fifteen patients underwent Type II resection without Type IV involvement, whereas six patients had combined Type II/IV resection. There were no significant differences between groups in operative time, blood loss, complications, local recurrence, postoperative metastasis, or disease mortality. Systematic review yielded 69 studies comprising 929 patients who underwent internal hemipelvectomy with acetabular resection. Of these, 906 (97.5%) had only Type II resection while 23 (2.5%) had concomitant Type II/IV resection. While overall complication rates were comparable, Type II resection alone produced significantly fewer neurological complications when compared to Type II resection with sacral extension (3.9% vs. 17.4%, p = .001). No significant differences were found between rates of wound complications, infections, or construct failures. Local recurrence, postoperative metastasis, and survival outcomes were similar. Type II internal hemipelvectomy without Type IV resection on average produced higher postoperative MSTS functional scores than with Type IV resection.

Conclusion: Surgical treatment of pelvic tumors remains challenging and requires meticulous preoperative planning and execution. In this series, there were no differences between the two groups. After a comprehensive systematic review we found that operative parameters, local recurrence or systemic metastasis, implant survival, and disease mortality were comparable in patients undergoing Type II internal hemipelvectomy alone compared to patients undergoing some combination of Type II/IV resection. However, compound resections increased the risk of neurological complications and poorer functional results thereby demonstrating the need for careful consideration of the operative risks, desired postoperative functional recovery, and oncological prognosis on a case by case basis.