Of the total 64 patients, 57 patients had removal of instrumentation, and had an inclusive follow-up. The AVH, PVH, VBA, kyphotic angle reduction, and SI are presented in Tables and (Figs. , ). Using paired t test significance testing, the differences between the pre-operative and post-operative numbers were all significant in all groups (P < 0.01). The difference between the pre-removal to latest follow-up numbers was also significant in all groups (P < 0.01). From this observation, there is a statistically significant increase in vertebral correction post-operatively. However, there is also a statistically significant decrease in vertebral correction after implant removal.
Vertebral body angle (VBA), local kyphotic angle (LKA), and sagittal index (SI) (average degrees, minimum to maximum)
L2 fracture ASIA E with anterior column compression treated with indirect reduction and fixation without fusion pre-operatively (a), post-operatively (b), pre-instrumentation removal (c) and 5 years after instrumentation removal (d)
The average calculated normal canal diameter at the injury level (Y) was 18.3 mm. The corresponding pre-operative value was (X1) 11.0 mm, for a spinal canal narrowing percent (NR1) of 41.4%. The latest follow-up values showed that the canal diameter was restored, on average, to 16.1 mm at the injury level (X2). At this follow-up, the canal was compromised (NR2), in AP diameter, about 13.7%. On average, the middle sagittal diameter increased 5.1 mm with reduction. The narrowing ratio (NR) reduction was 27.6% (Fig. ). Comparisons between pre-operative and latest follow-up values were both significant at P < 0.01.
At latest follow-up, 64 cases were neurologically assessed. Of these cases, 3 were ASIA A, 0 B, 3 C, 6 D, and 52 ASIA E grades. 12 patients, who were graded lower than E, were noted to have bowel or bladder disturbances. The three patients with a pre-operative neurological status of ASIA A had no improvement at latest follow-up, but all other patients had improvement of at least one ASIA grade (Table ).
Of the patients with Frankel E neurological status, 52 had the Oswestry index functional evaluation at latest follow-up. The functional disorders index mean score was 16.7 ± 18.5 and was graded as excellent in 41, good in 7, and poor in 4 patients. Of these 52 patients, 76.9% had excellent or good function.
Pre-operatively all patients were graded as P4 on the Denis pain scale. At latest follow-up there was pain reduction in all patients but one: 28 P1, 29 P2, 6 P2, and 1 P4. The one patient with a P4 rating was found to have a disk herniation at latest follow-up.
In this series of 64 patients, there were no infections, no neurological deterioration, and no deep venous thrombosis (DVTs). A total of 57 patients had hardware removal. Two patients had implant failure at 10 months, one patient had failure at 12 months and another patient, who did not want hardware removal, was incidentally found to have broken hardware at 48 months. Of these four patients with hardware failure, none reported any pain.
At latest follow-up four screws were not in the ideal location. Three screws had broken the medial wall, but no patient reported any neurological problems. One screw was found to have broken out laterally, but this patient also did not have any neurological problems. After these fractures healed, the screws were removed without any sequelae.
Additionally, after 10–12 months four screws were found to be broken. This included one cranial level screw failure caused by fatigue in two patients and one patient with both cranial screws broken at 12 months.