Effects of teriparatide on cementless bipolar hemiarthroplasty in patients with osteoporotic femoral neck fractures

Abstract

Background: For osteoporotic femoral neck fractures, suitable bone-implant stability is critical for pain relief, early return to daily activities and reduction of complications. Teriparatide (parathyroid hormone [PTH1-34]) can improve bone-implant stability in some basic studies. However it's use in osteoporotic femoral neck fractures treated by cementless hemiarthroplasties for the beneficial effects on bone-implant stability is sparse in the literature. The aim of this study was to determine if post-operative teriparatide administration can reduce femoral stem migration and improve early functional recovery and health-related quality of life (HRQoL).

Methods: Between 2010 and 2014, patients with osteoporotic femoral neck fracture who underwent cementless bipolar hemiarthroplasty were included into this retrospective cohort study. Group A included patients treated with cementless bipolar hemiarthroplasty only; Group B patients had additional teriparatide. Demographic data, complications, radiographic and functional outcomes as well as health-related quality of life (HRQoL) were compared.

Results: There were 52 hips in group A (no teriparatide) and 40 hips in group B (patient who received teriparatide). The subsidence of the femoral stem tended to be significantly decreased in the teriparatide group at 6 and 12 weeks post-operatively (p = 0.003 and p = 0.008, respectively). The Harris Hip Score (HHS) increased significantly from pre-operation to 6 weeks post-operatively and thereafter up to one year in both groups. However, there were no significant differences in terms of subsequent fracture, mortality, HHS, and HRQoL between two groups during the entire study period.

Conclusions: Teriparatide significantly reduces the subsidence of the cementless femoral stem in elderly patients in the early post-operative period, but this benefit does not reflect better functional outcomes and HRQoL. Further prospective randomized large-scale cohort study is warranted for evidence-based recommendations.

Keywords: Femoral neck fracture; Hip arthroplasty; Implant migration; Osteoporosis; Teriparatide.

Fig. 1

a Plain X-ray of the implanted femoral components taken immediately after surgery. The implant (PROFEMUR® Z) fitted at the metaphyseal-diaphyseal junction and the proximal diaphysis. The vertical distance between the lateral shoulder of the prosthesis and the superior tip of the greater trochanter on the radiograph was recorded as A; the distance from the lateral shoulder of the prosthesis to the distal tip of the prosthesis was recorded as B. b Plain X-ray of the implanted femoral components taken on follow-up. When measuring subsidence, corrections were made using the ratio of vertical distance between the lateral shoulder of the prosthesis to the distal tip of the prosthesis (B’/B). The corrected vertical distance between the lateral shoulder of the prosthesis and the superior tip of the greater trochanter was calculated using the equation: A X (B’/B). The subsidence was calculated as A’ – A X (B’/B)

Fig. 2

Assessment of the femoral stem-canal ratio. A line was drawn along the lateral margin of the lateral cortex and extended, and then the width between this line and the medial cortex was measured (C-D). Femoral stem-canal ratio was defined as the ratio of the width of the femoral component to the width of the medullary canal (E-F/C-D). Satisfactory was recorded when the ratio was more than 80 %. Radiographic evaluation originally appeared in J Bone Joint Surg Br 1993;75:6-13. E-F: the width of the femoral component

Fig. 3

The migration pattern of the femoral components. The values are the mean for the teriparatide and control groups on follow-up intervals immediately after surgery and at 6 and 12 weeks and 6 and 12 months. The subsidence of the stem was significantly decreased in the teriparatide group compared to the control group at each time point. The distal migration of the stem reached a plateau phase at 6 months and 12 months post-operatively in both groups. *p < 0.05, Mann-Whitney U test