Weekly injection of teriparatide for bone ingrowth after cementless total knee arthroplasty.

PURPOSE To compare bone mineral density (BMD) in patients with or without weekly injection of teriparatide to promote bone ingrowth after cementless total knee arthroplasty (TKA). METHODS Records of 8 men and 32 women (mean age, 75.6 years) who underwent cementless TKA for medial knee osteoarthritis with (n=20) or without (n=20) once-weekly subcutaneous/hypodermic injection of teriparatide for 48 weeks were reviewed. BMD and bone volume/total volume (BV/TV) of the bone-prosthesis interface of the proximal tibia in 6 regions of interest (ROI) were assessed at 3, 6, 9, and 12 months using multi-detector computed tomography. RESULTS Patients with or without weekly injection of teriparatide after cementless TKA were comparable in terms of baseline characteristics and pre- and post-operative knee range of motion and Knee Society knee and function scores. In ROI 1 (medial), ROI 3 (anteromedial), and ROI 4 (posteromedial), the BV/TV increased throughout the postoperative period in patients with weekly injection of teriparatide and declined after 6 months in patients without weekly injection of teriparatide. These 3 ROIs of the 2 groups differed significantly only in BMD at 6, 9, and 12 months. In ROI 2 (lateral), ROI 5 (anterolateral), and ROI 6 (posterolateral), both BV/TV and BMD showed a decreasing trend, and these 3 ROIs of the 2 groups did not differ significantly. CONCLUSION Weekly injection of teriparatide after cementless TKA promoted bone ingrowth mostly in the medial aspect of the bone-prosthesis interface.