Nanohydroxyapatite/polyamide 66 strut subsidence after one-level corpectomy: underlying mechanism and effect on cervical neurological function

The aim of this study was to investigate n-HA/PA66 strut subsidence after one-level in Anterior cervical corpectomy decompression and fusion (ACCF) and its effect on treatment outcomes to better understand the underlying mechanism and related risk factors. In total, 56 patients undergoing ACCF using n-HA/PA66 struts were analysed retrospectively. After a 12-month follow-up, the height of the fused segments and fused intervertebral heights were measured, the neurological findings were evaluated using the Japanese Orthopedic Association (JOA) and axial pain was assessed using a Visual Analogue Scale(VAS). Subsidence was defined as a decrease in the height of the fused segments or the fused intervertebral body greater than 3 mm compared with that on postoperative day one, and all patients were assigned to the n-HA/PA66 strut subsidence and control groups. In total, 45 patients experienced n-HA/PA66 strut subsidence during the postoperative (3 ± 2.42/3.11 ± 2.01) months. No significant differences were observed in sex, age, hospitalization time, surgical haemorrhage,bone mineral density (BMD), or height in the n-HA/PA66 strut group. The JOA and VAS of neck pain in the control group improved more than those in the subsidence group, suggesting that subsidence might be correlated with poor improvement of neurological function. In conclusion, n-HA/PA66 strut subsidence is a common complication after ACCF, and the reduced height of the postoperative fused segments and the height reduction in the postoperative fused intervertebral bodies are independent risk factors of n-HA/PA66 strut subsidence.