Developmental Patterns and Risk Factors of Scoliosis After Hemipelvectomy for the Pelvic Bone Tumor

Abstract

Background: Postoperative scoliosis is often seen after hemipelvectomy for malignancies involving the pelvic area, but the details remain unclear. The objectives were to investigate the development patterns and risk factors of scoliosis after hemipelvectomy.

Methods: We retrospectively reviewed 30 patients who underwent hemipelvectomy at our hospital between 1998 and 2020. The risk factors of scoliosis with a Cobb angle of ≥10° were investigated.

Results: The postoperative Cobb angle significantly increased in all patients compared with the preoperative one (p < 0.001), and the change ratio of the Cobb angle was significantly higher during the first postoperative year than thereafter. The external hemipelvectomy (EH) group demonstrated a larger Cobb angle and a higher change ratio than the internal hemipelvectomy group. Nine patients developed scoliosis with a final Cobb angle of ≥10°, and the risk factors were EH (p = 0.017), P1+2+3+4 resection according to the Enneking classification (p = 0.005), iliac crest resection (p = 0.004), L5/S resection (p = 0.020), and no pelvic ring reconstruction after hemipelvectomy (p = 0.004).

Conclusions: Approximately 30% of patients who underwent hemipelvectomy developed scoliosis with a Cobb angle of ≥10°, and this angle increased rapidly during the first postoperative year. Hence, careful follow-up of scoliosis is required after hemipelvectomy.

Keywords: hemipelvectomy; sarcoma; scoliosis.

Figure 1

CT scout image of a patient who had undergone hemipelvectomy.

Figure 2

Cobb angle change of all patients. (a) Time-course change of the Cobb angle. The Cobb angle increased over time after hemipelvectomy. (b) The change ratio of the Cobb angle. The change ratio was prominent during the first year after hemipelvectomy. In the x-axis, Pre means the preoperative time point, and PostX means X years after hemipelvectomy. The intervals between Post1–Pre, Post2–Post1, and Post3–Post2 were described as 1st, 2nd, and 3rd intervals, respectively.

Figure 3

Cobb angle change in the external hemipelvectomy group and internal hemipelvectomy group. (a) Time-course change of the Cobb angle in the external hemipelvectomy (EH, blue box plot) group and internal hemipelvectomy (IH, orange box plot) group. The Cobb angle in the EH group was significantly larger than that in the IH group. (b) The change ratio of the Cobb angle in each group. The change ratio was higher in the EH group than in the IH group during the first year after surgery. In the x-axis, Pre means the preoperative time point, and PostX means X years after hemipelvectomy.

Figure 4

Effect of L5/S resection on Cobb angle change in the external hemipelvectomy group. (a) Time-course change of the Cobb angle in the L5/S-resected group (deep blue box plot) and L5/S-preserved group (light blue box plot) among the EH groups. The Cobb angle was significantly larger in the L5/S-resected group than in the L5/S-preserved group. (b) The change ratio of the Cobb angle in each group. The change ratio was higher in the L5/S-resected group than in the L5/S-preserved group between the 1st and 2nd intervals. In the x-axis, Pre means the preoperative time point, and PostX means X years after hemipelvectomy.

Figure 5

Relationship between iliac crest resection and the curve direction of scoliosis. (a) A patient who underwent EH with iliac crest resection demonstrated a convex curve toward the ipsilateral side of the resection. (b) A patient who underwent EH with iliac crest preservation demonstrated a convex curve toward the contralateral side of the resection. Red arrows indicate the convex side.