Abstract
This study evaluates how 2 different total hip arthroplasty (THA) stems compares regarding adaptive bone remodelling. The stems are both proximally porous coated, aiming for proximal fixation, but with different dispersal of the coating. They are also differently designed regarding the distal tip of the stem. We aimed to investigate if there is a difference in periprosthetic adaptive bone remodelling between two different designs. From February 2016 to September 2017, we randomised 62 patients, 1:1 (mean age = 64 years, Female/Male = 28/34), scheduled for an uncemented THA to receive either an EBM or a BM THA stem. We performed dual-energy x-ray absorptiometry (DEXA) scans within a week after surgery and at 3, 6, 12 and 24 months with measurements of bone mineral density (BMD) in the 7 Gruen zones (region of interest (ROI) 1–7). Additionally, Oxford Hip Score and Harris Hip Score were collected at 6, 12 and 24 months. We found a decrease in BMD between the postoperative and the 24-months values in all ROIs for both stems. The greatest decrease over time was seen for both groups in the ROI1 (BM = − 8.4%, p = 0.044, and EBM = − 6.5%, p = 0.001) and ROI7 (BM = − 7%, p = 0.005, and EBM = − 8.6%, p < 0.0005). We found a tendency in ROI2–4 of a higher degree of bone loss in the EBM group. However, this difference only continued beyond 6 months in ROI4 (24 months: BM = − 1.2% and EBM = − 2.8%, p = 0.001). The stems show similar adaptive bone remodelling and are clinically performing well.
Highlights
Total hip arthroplasty (THA): heralded in 2007 as the operation of the c entury1
In the Echo Bi-Metric Full Proximal Profile (EBM) group, 1 participant did not want to proceed in the study beyond 12 months, and in 1 case we had to exclude the patient from the study at 24 months because of technical difficulties
At 24 months we saw the most marked decrease in bone mineral density (BMD) in both groups in the ROI1 (BM = − 8.4%, p = 0.04, and EBM = − 6.5%, p = 0.001) and ROI7 (BM = − 7%, p = 0.005, and EBM = − 8.6%, p < 0.0005) followed by ROI2 (BM = − 4%, p = 0.007, and EBM = − 5.2%, p < 0.0005) (Table 2)
Summary
Total hip arthroplasty (THA): heralded in 2007 as the operation of the c entury. From one day to another, patients can walk again, go skiing again and play golf again. From previous studies we know that the bone mineral density (BMD) (g/cm2) decreases directly after surgery in response to the operative trauma and postoperative immobilisation, later on, because of the phenomenon called stress-shielding and in some patients, because of foreign body r eaction. This study aimed to investigate the regional adaptive bone remodelling between 2 slightly different designs of porous-coated uncemented titanium alloy hip prosthesis; the Bi-Metric Porous Primary (BM) stem and the Echo Bi-Metric Full Proximal Profile (EBM) stem. This evaluation was found relevant because the BM has been on the market for > 30 years with satisfying results; The EBM is the successor of the BM, made with a design based on the BM design but with theoretical enhancements. In 2018 784 BM stems were used and 626 EBM stems were used in Denmark (of a total of 7054 cementless THAs; the Corail stem being the most used (3148 in 2018))
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
