Purpose of the study: We conducted a prospective randomized study to compare use of macroporous biphasic calcium phosphate ceramic and bone autografts for filling medial open wedge osteotomies of the proximal tibia.
Material and methods: This phase III pragmatic clinical trial was designed for direct patient benefit. Randomization was performed in the operating room after completing the osteotomy. Twenty-six men and 14 women, mean age 51 years (range 19–75 years) were included. A biomaterial implant was used for 22 patients and an autograft for 18. Mean correction was 10 mm (range 6–15). One patient was excluded from the analysis, no patient was lost to follow-up. All patients were reviewed at minimum two years follow-up.
Results: At three months, knees were less painful with less subjective functional impact after filling with an autograft (pain VAS 3.1 versus 2.1 and function VAS 3.4 versus 2.5). These results were more balanced at six months (pain 1.6 versus 1.8 and function 1.8 versus 2.1) and remained stable at one and two years. The IKS knee scores were symmetrical at one at two years for both groups (IKS1 93 versus 86 and IKS2 90 versus 90). Bone healing was achieved within the usual delay. Axial alignment was stable at two years in both groups. There were eleven complications (28%), nine requiring revision: infected hematoma (n=1), intraoperative vascular injury without serious consequences (n=1), loss of correction (n=2), nonunion after filling with biomaterial (n=1), iliac abscess after filling with autograft (n=2) and painful calcification of the iliac region requiring resection (n=1).
Discussion: We observed three factors which can favor mechanical failure after filling with a ceramic material: intraoperative rupture of the lateral hinge, obesity, and excessively early unprepared weight bearing.
Conclusion: Although the difference did not reach significance, the risk of mechanical complications appears greater with macroporous en bloc ceramic filling. This material is less tolerant to comorbid conditions (obesity) and requires very precise technique as well as careful observance of postoperative care (no early weight bearing). Nevertheless, this method does have the advantage of avoiding painful sequelae and complications related to harvesting the iliac graft.
