Three-Dimensional-Printed Porous Tantalum Wedge Shows Promising Early Results for Opening-Wedge High Tibial Osteotomy: A Retrospective Comparative Study With Mean 50-Month Follow-Up.

Purpose: Bone void fillers are essential for successful outcomes in opening-wedge high tibial osteotomy (OWHTO), a procedure that corrects varus knee misalignment and alleviates medial compartment pain. However, the best filler for OWHTO is still uncertain. This study compared the clinical and radiographic results of using three-dimensional-printed (3DP) porous tantalum wedges versus allogeneic chip bone as fillers in OWHTO, aiming to provide a reference for clinical decision-making.

Methods: This exploratory-retrospective matched-cohort consecutively enrolled study included 20 patients (10 per group) who were treated between January 2020 and December 2022, with Group A (3DP porous tantalum) selected from a large trial and Group B (allogeneic chip bone) matched by age, gender, and varus severity.

Inclusion criteria: young, active patients with tibial varus and complete follow-up; exclusions: knee infection, instability, contracture, dislocation, or pan-compartmental osteoarthritis. Postoperatively, early full-weight-bearing rehabilitation was applied, with follow-ups at 6 weeks, 3 months, 6 months, 12 months, and annually.

Primary outcome: bone healing (modified van Hemert score, standing radiographs).

Secondary outcomes: hospital for special surgery knee score (HSS), visual analogue scale (VAS), time to full-weight-bearing walking, and radiographic parameters (joint line convergence angle [JLCA], femur-tibia angle [FTA], hip-knee-ankle angle [HKA], mechanical medial proximal tibial angle [mMPTA], mechanical axis deviation [MAD], weight-bearing line [WBL] ratio, posterior tibial slope [PTS]). Postoperative complications were recorded and compared between both groups. Statistical analyses used the Mann-Whitney U test for continuous data and the chi-square test for categorical data.

Results: Mean age was 48.7 ± 3.9 years, with a mean follow-up of 50.0 ± 7.0 months (range: 29.4-59.0). Group A had significantly higher bone healing scores at 6 weeks, 3 and 6 months (3.0 ± 0.8 vs. 1.6 ± 1.0, 3.4 ± 0.5 vs. 2.0 ± 0.9, 4.3 ± 0.5 vs. 2.9 ± 0.9, respectively, all p < 0.01), with no difference at 1 year (4.8 ± 0.4 vs. 4.4 ± 0.5, p = 0.075). Time to full-weight-bearing walking was significantly shorter in Group A (18.7 ± 3.2 vs. 54.4 ± 15.3 days; p < 0.001). Both groups showed significant postoperative improvements in VAS, HSS scores, and radiographic parameters (MAD, WBL ratio, mMPTA, HKA; all p < 0.01 vs. preoperative values), with no intergroup differences in these metrics (preoperative or postoperative). Overall complication rates were similar (20% vs. 60%; p = 0.074), but Group A had a lower incidence of delayed union (0% vs. 40%; p = 0.011). The statistical power for 1-year bone union grades was 0.65 (G*Power, effect size = 0.883).

Conclusion: 3DP porous tantalum wedges in OWHTO accelerate bone healing (up to 6 months), reduce time to full-weight-bearing walking, and lower delayed union rates compared to allogeneic chip bone, thereby establishing them as a promising option for future surgical interventions. Further large-scale, long-term trials are needed to confirm these benefits.