PERIPROSTHETIC bone density after unicompartmental knee arthroplasty may follow a predictable early loss then recovery pattern.
Study Design and Patient Cohort
In this prospective cohort study, investigators evaluated dynamic changes in periprosthetic bone mineral density around medial unicompartmental knee arthroplasty in patients with anteromedial knee osteoarthritis. Forty adults with anteromedial osteoarthritis undergoing cemented Oxford medial unicompartmental knee arthroplasty performed by a single surgeon were followed between January 2020 and January 2024. Dual-energy X ray absorptiometry was used to quantify periprosthetic bone mineral density preoperatively and at one, three, six, and twelve months postoperatively across defined tibial and femoral regions of interest.
Periprosthetic Bone Density After Unicompartmental Knee Arthroplasty
Periprosthetic bone mineral density declined rapidly in the early postoperative period. Significant reductions were observed at one and three months after unicompartmental knee arthroplasty, consistent with early stress redistribution and postoperative bone remodeling around the implant. From six to twelve months, periprosthetic bone mineral density increased, indicating partial recovery over time.
By the six and twelve month timepoints, changes in bone mineral density around the tibial component regions of interest and the posterior aspect of the femoral stem appeared stable, with no significant differences between these later assessments. These findings suggest that most measurable remodeling around the cemented Oxford prosthesis occurs within the first six months, followed by a plateau phase rather than continuous loss.
Clinical Implications for Postoperative Management
Aseptic loosening remains a key cause of failure after knee arthroplasty, and periprosthetic bone loss is an established contributor in total knee arthroplasty. Although this study did not directly assess loosening, the observed rapid decline in periprosthetic bone mineral density within the first three months after unicompartmental knee arthroplasty highlights a potential therapeutic window. The authors suggest that early anti osteoporotic treatment in selected patients may help preserve periprosthetic bone support during this vulnerable period.
For clinicians managing knee osteoarthritis with unicompartmental knee arthroplasty, these data reinforce the importance of monitoring bone health, particularly in individuals at higher baseline risk of low bone mineral density. Integrating bone health optimization into perioperative pathways may help reduce future loosening risk and support longer term implant survival.
Reference: Wei L et al. Changes in periprosthetic bone mineral density after medial unicompartmental knee arthroplasty: a prospective cohort study. Int Orthop. 2025;doi:10.1007/s00264-025-06711-0.
