Hydroxyapatite-Coated Screws Versus Titanium Triangular Dowels for Sacroiliac Joint Fusion: Results From a Nonrandomized Prospective Outcome Study

Objective: This is a single-surgeon series that prospectively evaluates the results of sacroiliac joint (SIJ) fusion for patients with SIJ dysfunction using hydroxyapatite-coated screws (HACSs) compared with titanium triangular dowels (TTDs).

Methods: A total of 113 patients underwent SIJ fusion surgery between 2013 and 2018 at the University Hospital Llandough to treat symptomatic SIJ dysfunction not responding to nonoperative measures. Of the 113 patients, 40 were treated with HACSs and 73 with TTDs. Patient-reported outcomes measures (PROMs) were collected preoperatively and at 12 months postoperatively, including the 36-item short-form health survey, Oswestry disability index, EuroQol-5D-5L, and Majeed pelvic score. Patients with ongoing symptoms were followed up beyond the study period.

Results: Of the 113 patients, 33 completed follow-up in the HACS group compared with 61 in the TTD group. Both groups had comparable preoperative PROMs; however, the postoperative PROMs were significantly better in the TTD group. Additionally, 21 patients (63%) in the HACS group had radiological evidence of screw lysis compared with 5 patients (9%) in the TTD group. A subgroup analysis revealed less significant improvement in PROMs for patients with screw lysis compared with those without. Four patients were offered further revision surgery.

Conclusions: Minimally invasive SIJ fusion has been shown to have good clinical outcomes for select patients. However, our experience shows that HACSs are associated with a high rate of screw lysis and poorer patient outcomes compared with TTDs. Therefore, we recommend the use of TTDs instead of HACSs for SIJ fusion surgery.