Effect of teriparatide (rh-PTH 1-34) versus bisphosphonate on the healing of osteoporotic vertebral compression fracture: A retrospective comparative study

Abstract

Background: Teriparatide (recombinant human parathyroid hormone 1-34) is increasingly used for the treatment of severe osteoporosis because it stimulates bone formation and may potentially enhance fracture healing. The objective of this study was to investigate the effects of teriparatide versus a bisphosphonate on radiographic outcomes in the treatment of osteoporotic vertebral compression fractures (OVCF).

Methods: A total of 98 patients undergoing non-operative treatment for recent single-level OVCF were reviewed retrospectively. Thirty-eight patients were treated by a once-daily subcutaneous injection of 20 micrograms of teriparatide (TPD group), whereas 60 patients received 35 mg of alendronate weekly (BP group). Except for these medications, the same treatment protocol was applied to both groups. The radiographic assessments included union status, vertebral kyphosis, and mid-vertebral body height. The rates of fracture site surgical intervention were also compared between the two groups. The mean follow-up period was 27 months (median 22.5, range 2 - 75 months).

Results: Cox regression analysis showed that TPD reduced the time-to-union (adjusted relative hazard ratio: 1.86, 95% C.I.: 1.21 - 2.83). The union rate at six months after treatment was 89% in the TPD group and 68% in the BP group; the surgical intervention rate was significantly higher in the TPD group (p = 0.026, adjusted odds ratio: 8.15, 95% C.I.: 2.02 - 43.33). The change in local kyphosis was 4.6° in the TPD group and 3.8° in the BP group (p = 0.495, paired t-test). The change of mid-vertebral body height was 4.4 mm in the TPD group and 3.4 mm in the BP group (p = 0.228, paired t-test). Fracture site surgical interventions were not required in the TPD group; however, two patients in the BP group eventually underwent surgical treatment for symptomatic non-union or vertebral collapse.

Conclusions: This retrospective study suggests that teriparatide may enhance fracture healing and improve the union rate in OVCF.

Keywords: Bisphosphonates; Osteoporosis; Osteoporotic vertebral compression fracture; Recombinant human parathyroid hormone 1–34; Teriparatide; Union rate.

Fig. 1

Bridging bone around a vertebral cleft. Although a vertebral cleft was observed, the presence of bony bridging around the fractured vertebra (arrows) was interpreted as diagnostic of radiographic union

Fig. 2

Kaplan-Meier curves for time-to-union in the TPD group versus the BP group. The Kaplan-Meier curve showed the time course of union in the TPD group and the BP group (p < 0.001, log-rank test). The thin black arrow shows the end of follow-up with non-union, and the bold white arrow indicates the end of follow-up due to surgical intervention. The union rate was 89% in the TPD group and 68% in the BP group by six months after treatment (p = 0.026, Fisher’s exact test). At the final follow-up, 97% of those in the TPD group and 90% of those in the BP group achieved a stable union (p = 0.243, Fisher’s exact test)

Fig. 3

Mid-vertebral body height and vertebral kyphosis angle. Vertebral body height was 17.4 ± 0.7 mm in the TPD group and 16.6 ± 0.9 mm in the BP group before treatment. This measure decreased to 13.0 ± 0.7 mm and 13.2 ± 0.9 mm at the final follow-up, respectively (p = 0.228, paired t-test). The vertebral kyphosis angle was 8.6 ± 1.0° in the TPD group and 10.8 ± 0.8° in the BP group before treatment. This angle increased to 13.2 ± 1.3° and 14.6 ± 1.0° at the final follow-up, respectively (p = 0.495, paired t-test)

Fig. 4

Duration of prior bisphosphonate use and time-to-union of osteoporotic vertebral fracture. This graph showed the relationship between the duration of bisphosphonate use at the time of OVCF and the OVCF time-to-union. The white round mark indicates the TPD group and the black round mark indicates the BP group. The duration of bisphosphonate use did not correlate with OVCF time-to-union in either group