Assessment of unloading effects after open wedge high tibial osteotomy using quantitative bone scintigraphy

Introduction: We evaluated changes in bone tracer uptake (BTU) in open wedge high tibial osteotomy (OWHTO) and determined if BTU correlates with clinical symptoms, postoperative alignment, or cartilage regeneration after OWHTO. Materials and methods: Seventy-five knees in 64 patients who underwent OWHTO for medial compartment osteoarthritis were enrolled in this retrospective study. All cases were assessed preoperatively and at plate removal using bone scintigraphy. Visual analog scale (VAS), Japanese Orthopedic Association (JOA) score, Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score (KOOS), and the weight-bearing line ratio (WBLR) were assessed preoperatively and at plate removal. In addition, cartilage regeneration was evaluated at plate removal. We assessed changes in BTU for the medial and lateral compartment after OWHTO and the correlations between BTU of the medial compartment and all other parameters were analyzed. Results: Postoperatively, all outcome measures significantly improved: mean VAS 61.4 +/- 18.3 to 9.5 +/- 8.2, mean JOA score 65.1 +/- 11.5 to 94.7 +/- 6.0, mean OKS 29.4 +/- 8.1 to 42.3 +/- 4.1, mean KOOS 57.0 +/- 14.3 to 83.7 +/- 9.6, mean WBLR 22.8 +/- 10.9 to 70.0 +/- 9.4. Cartilage regeneration was observed in 53 knees (70.7%). BTU of the medial compartment significantly decreased after OWTHO, whereas no increased postoperative BTU was found in the lateral compartment. Postoperative BTU of the medial compartment significantly correlated with VAS, KOOS, and WBLR. No statistically significant associations were found between BTU and cartilage regeneration. Conclusions: OWHTO significantly decreased BTU of the medial compartment, which correlated with knee pain and postoperative mechanical alignment. Unloading effects of OWHTO led to pain relief after surgery, regardless of cartilage regeneration. (c) 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.