Clinical and Radiological Outcomes of Oral Bisphosphonate Therapy Combined with Conservative Treatment in Subchondral Bone Marrow Edema of the Knee: A Retrospective Cohort Study

Background/Objectives: Subchondral bone marrow edema (BME) of the knee often causes persistent pain despite conservative treatment, and evidence supporting oral bisphosphonates is limited. We compared conservative treatment alone with conservative treatment plus oral alendronate. Methods: This retrospective cohort study included 82 patients with MRI-confirmed subchondral BME of the knee treated between January 2020 and January 2025. Patients received conservative treatment alone (n = 44) or conservative treatment plus alendronate 70 mg weekly for three months (n = 38). Visual Analog Scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were assessed at baseline and three months. Radiological response was assessed on follow-up MRI as the percentage reduction in BME area. Results: Both groups improved significantly at three months. The alendronate group showed greater reductions in VAS (4.0 ± 1.4 vs. 3.2 ± 1.3 points, p = 0.009) and total WOMAC scores (25.5 ± 8.9 vs. 19.8 ± 8.6 points, p = 0.002). Median time to full weight-bearing was shorter with alendronate (7 vs. 9 weeks, p = 0.021), and complete BME regression was more frequent (42.1% vs. 18.2%, Fisher’s exact p = 0.028). After adjustment for Kellgren–Lawrence grade, alendronate was associated with a favorable radiological response (OR = 3.66, 95% CI: 1.18–11.31, p = 0.024). No serious adverse events were recorded. Conclusions: Adding oral alendronate to conservative treatment was associated with greater clinical improvement, earlier full weight-bearing, and a more favorable radiological response at three months. Prospective randomized studies are needed to confirm these findings.