Percutaneous modified iliac screw fixation: technique and clinical experience

S1 pedicle screws are often associated with loosening and breakage. Conventional iliac screw (CIS) or S2 alar-iliac (S2AI) techniques improve stability but have their own drawbacks. The percutaneous modified iliac screw (PMIS) technique was developed to overcome these issues with a less invasive approach.

This study is a retrospective case series conducted by a single surgeon. The PMIS technique uses two virtual fluoroscopic reference lines to avoid critical structures and allows percutaneous insertion of the screw into the intra-iliac cancellous corridor. Between 2014 and 2025, ten patients (2 males, 8 females; mean age 59.9 years) underwent sacropelvic fixation using the PMIS approach. Indications included spinal metastasis (n = 8), infection (n = 1), and degeneration (n = 1). Radiographs were used to evaluate instrumentation, complications, and spinopelvic parameters (PI, PT, SS) before surgery and at the final follow-up.

No infection, screw prominence, or screw-related complications were noted. One revision was needed due to progression of a spinal infection unrelated to the PMIS. Radiographic measurements of PI, PT, and SS remained largely unchanged between preoperative and final follow-up.

PMIS provides a safe and minimally invasive option for sacropelvic fixation. It avoids the limitations of CIS and S2AI while reducing soft tissue dissection. Although early results are promising, larger studies are needed to validate the effectiveness and broader clinical use of this method.