Percutaneous insertion of craniocaudal expandable implants for vertebral compression fracture

4.1 In a randomised controlled trial (RCT) of 300 patients treated by a vertebral craniocaudal expandable implant (n=153) or by balloon kyphoplasty (n=147), procedure success at 12 months was 94% (120/127) in the implant group and 98% in the balloon kyphoplasty group (no statistically significant difference between groups; -3%, Bayesian credible interval 9% to 2%). Procedure success was defined as a reduction in pain by 15 mm or more from baseline on the 100 mm visual analogue scale (VAS), maintenance of function (did not worsen by 10 or more points) or improvement in function from baseline on the 100-point Oswestry disability index (ODI), and no device-related serious adverse events.

4.2 In the RCT of 300 patients treated by a vertebral craniocaudal expandable implant (n=153) or by balloon kyphoplasty (n=147), there was a statistically significant improvement from baseline in the mean VAS scores for pain (0 to 100 mm, from no pain to worst imaginable pain) in both groups at follow-up. In the implant group, the mean VAS score changes (± standard deviation, SD) from baseline were: ‑59.8±28.9 (n=140) at 30 days, ‑68.6±25.9 (n=135) at 6 months and -70.8±26.3 (n=127) at 12 months. In the balloon kyphoplasty group, the mean VAS score changes from baseline were -61.1±26.9 (n=135) at 30 days, -65.2± 27.4 (n=126) at 6 months and -71.8±23.5 (n=126) at 12 months. No statistically significant differences between groups were seen at follow-up. In a retrospective matched-paired comparative study of 52 patients treated by a vertebral craniocaudal expandable implant (n=26) or by balloon kyphoplasty (n=26), the mean VAS scores (±SD) improved in both groups from 87.6±12.8 before the procedure to 10.8±20.8 at 6 months in the implant group and from 83.1±14.9 to 24.6±11.0 in the balloon kyphoplasty group (p value within group not reported). VAS scores 6 months after the procedure were statistically significantly different between groups (p<0.0001).

4.3 In an observational study of 103 patients treated by a craniocaudal expandable implant, the rate of patients with no analgesic treatment improved from 6% (6/103) at baseline to 27% (28/103) at 48-hour follow-up, 67% (61/91) at 3-month follow-up and 73% (57/78) at 12-month follow up (p value not reported).

4.4 In the RCT of 300 patients treated by a vertebral craniocaudal expandable implant (n=153) or by balloon kyphoplasty (n=147), the mean ODI score (0 to 100, from no disability to maximum disability) changes from baseline were -31.4±21.9 (n=140) at 30 days, -37.7±20.1 (n=135) at 6 months and -38.1±19.8 (n=127) at 12 months in the implant group. In the balloon kyphoplasty group, the mean ODI score changes from baseline were ‑34.6±20.4 (n=135) at 30 days, ‑38.4±20.4 (n=126) at 6 months and -42.2±21.7 (n=126) at 12 months. There was a statistically significant improvement in ODI scores within groups but not between groups (level of statistical significance not reported).

4.5 In an RCT of 185 patients treated by a vertebral craniocaudal expandable implant (n=92) or by balloon kyphoplasty (n=93), there was a statistically significant improvement in the mean short-form (SF)-36 (physical functioning domain) scores in both groups from 32±11 before the procedure to 65.8±15.6 at 1 year in the implant group and from 28±12 to 68±19.8 in the balloon kyphoplasty group (p=0.001 for both groups compared with baseline, but no statistically significant difference between groups at 1-year follow‑up, p=0.72). There was also a statistically significant improvement in the mean SF‑36 (mental health domain) scores in both groups, from 42±10 before the procedure to 64±11 at 1 year in the implant group and from 41±9 to 62±10 in the balloon kyphoplasty group (p=0.001 for both groups compared with baseline but no statistically significant difference between groups at 1-year follow-up, p=0.64).

4.6 In an RCT of 300 patients treated by a vertebral craniocaudal expandable implant (n=150) or by balloon kyphoplasty (n=150), there was a statistically significantly greater increase in vertebral body height after the procedure in the implant group than in the kyphoplasty group (p<0.05). In the implant group, vertebral height was restored by more than 50% in 85% of patients, by less than 50% in 12% of patients and there was no change in 3%. In the balloon kyphoplasty group, vertebral height was restored by more than 50% in 58% of patients, by less than 50% in 26% of patients and there was no change in 16%. In the retrospective matched‑paired comparative study of 52 patients treated by a vertebral craniocaudal expandable implant (n=26) or by balloon kyphoplasty (n=26), there was a statistically significant increase in anterior and mid-vertebral height (mean±SD) in both groups after the procedure. This increased from 21.06 ± 2.77 mm before the procedure to 22.41± 7.14 mm after the procedure (anterior) and from 18.36± 5.64 mm to 20.89± 6.00 mm (mid) in the implant group, and from 21.68 ± 2.08 mm to 25.09± 2.54 mm (anterior) and from 21.97± 1.78 mm to 25.29± 2.10 mm (mid) in the balloon kyphoplasty group (p<0.001 for the within-group comparison). At 6 months, vertebral height had not changed much from after the procedure in both groups: in the implant group, anterior vertebral height was 22.28 ± 6.85 mm and mid-vertebral height was 21.19± 6.08 mm, and in the balloon kyphoplasty group, anterior vertebral height was 24.56± 2.27 mm and mid-vertebral height was 24.91± 2.08 mm. In a prospective case series of 32 patients, the mean (±SD) Beck index (anterior edge height divided by posterior edge height) changed from 0.75± 0.14 before the procedure to 0.77± 0.14 at 12 months.

4.7 In the RCT of 185 patients treated by a vertebral craniocaudal expandable implant (n=92) or by balloon kyphoplasty (n=93) there was a statistically significant decrease in mean (±SD) wedge angle only in the implant group, from 13.7±7 degrees before the procedure to 7.80±6 degrees after the procedure (p=0.009). The mean wedge angle in the balloon kyphoplasty group decreased from 14.9±8 degrees to 11.5±7 degrees (p=0.067). Wedge angles after the procedure were not statistically significantly different between groups (p=0.11). In the prospective case series of 32 patients, there was a statistically significant decrease in the mean (±SD) vertebral kyphotic angle and in the mean Cobb angle from 9.0± 5.8 degrees before the procedure to 8.3± 5.6 degrees at 3 days and 8.3± 5.5 degrees at 12 months. For the mean (±SD) Cobb angle there was a statistically significant decrease from 12.3± 16.4 degrees before the procedure to 10.8± 16.4 degrees at 3 days and 10.8± 16.3 degrees at 12 months (p<0.05 for the comparisons at 12 months versus baseline).

4.8 In the RCT of 185 patients treated by a vertebral craniocaudal expandable implant (n=92) or by balloon kyphoplasty (n=93), there was residual kyphosis of 5 degrees or more at the final observation in 84% (69/82) of spines in the implant group and in 100% (86/86) of spines in the balloon kyphoplasty group (p<0.001).

4.9 The specialist advisers listed the following key efficacy outcomes: radiological parameters such as restoring and maintaining vertebral body height, alignment and sagittal balance, and functional outcome measures.