Types of operations monitored (N = 169).
| Operations | No. (%) of Cases |
| Anterior cervical discectomy and fusion | 72 (42.6%) |
| Anterior cervical discectom and fusion (revision) | 1 (0.6%) |
| Posterior cervical discectomy and fusion | 25 (14.8%) |
| Posterior occipital cervical fusion | 5 (3%) |
| Cervical corpectomy | 3 (1.8%) |
| Cervical discectomy | 4 (2.4%) |
| Thoracic corpectomy | 3 (1.8%) |
| Thoracic fusion (revision) | 4 (2.4%) |
| Thoracolumbar decompression and fusion | 17 (10%) |
| Lumbar discectomy and fusion | 1 (0.6%) |
| Lumbar fusion (revision) | 4 (2.4%) |
| Posterior thoracolumbar instrumented fusion (scoliosis correction) | 29 (17.2%) |
| Scoliosis correction (revision) | 1 (0.6%) |
| Removal of intervertebral disc prosthesis | 1 (0.6%) |