Modalities of failure of cement-augmented pedicle screws

Cement-augmented pedicle screw instrumentation procedures are performed for stabilization in patients with surgical spinal conditions with poor bone quality at the target levels. Although this is done to combat the risk of failure due to loosening, cutting out or pulling out of the screws, failure may still occur. The purpose of this study was to identify the modalities and rates of failure of CAPSI constructs to better predict occurrence of failure.

We retrospectively reviewed clinical data of patients who underwent CAPSI fusion procedures between 2010 and 2022. We collected pre, intra and post-operative clinical and radiographic data.

621 pedicle screws in 319 levels were augmented out of 1333 screws in 809 instrumented levels in 120 patients. F:M = 3:1; mean age 68.6 years and mean BMI 27.10. The mean length of follow up overall was 2.2 years (Range 7 days-11 years). The most common surgical indications were degenerative scoliosis and osteoporotic fractures. Construct failure occurred in 32 cases; seven cases were associated with trauma and 11 cases presented with a neurologic deficit. The most common modality of failure was osteonecrotic collapse (20 cases); proximal construct failure occurred in 22 cases; there was evidence of haloing at the screw-bone-cement interfaces in 23 out 32 cases. 21 out of 32 cases required revision surgical procedures within an average of 453 days.

Failure of CAPSI constructs occurred in 26.7% of patients. High occurrence of osteonecrotic collapse and haloing at the screw-cement-bone interfaces likely represents a relationship with construct failure.