Giant cell tumor of bone is a benign lesion that is ‘locally aggressive and potentially malignant’. The most common specific location of ‘GCT’ is about the knee (50–65%), followed by the distal radius (10–12%), sacrum (4–9%) and proximal humerus (3%–8%). The pelvis is recognized as an infrequent site of involvement accounting for as few as 2% to 3% of all giant cell tumors. Giant cell tumors often can reach an alarming size in the pelvis jeopardizing the surrounding structures.

Treatment options described in literature for pelvic giant cell tumors include radiation therapy; surgery with intralesional margin; surgery with an intralesional margin and physical adjuvants, and surgery with wide margins.

Following Type II (Periacetabular) resections the two preferred modes of reconstruction are either Saddle Prosthesis or Ilio femoral fusion. But, in patients with extensive periacetabular involvement with tumor extension into ilium the type II resection has to be combined with a Type I (Ilial) resection. This may result in insufficient ilium being available for reconstruction to consider either a iliofemoral fusion or a saddle prosthesis. In such situations we recommend Sacroiliofemoral fusion as a novel variation of iliofemoral arthrodesis.

We present two cases of GCT of pelvis with significant periacetabular involvement treated by Sacroiliofemoral fusion. A follow up at 2 years in both cases showed no recurrences, mean MSTS of 21 & TESS of 70.

This paper discusses the various treatment options for such extensive periacetbular giant cell tumors, operative technique for sacroiliofemoral fusion, outcome evaluation after 2 years by MSTS & Toronto Extremity Salvage scores.