Serial Quantitative Assessment of Load Redistribution After Medial Open-Wedge High Tibial Osteotomy

The maximum standardized uptake value (SUV_max), as determined on combined single-photon emission computed tomography and conventional computed tomography (SPECT/CT), can be an indicator of biomechanical changes due to the load redistribution effect after medial open-wedge high tibial osteotomy (MOW-HTO).

The purposes of this study were to (1) analyze serial changes in the SUV_max in the medial, lateral, and patellofemoral compartments after MOW-HTO and (2) identify the contributing factors that affect changes in the SUV_max. The hypotheses were that (1) an elevated SUV_max in the medial compartment would be transferred to the lateral compartment because of the load redistribution effect and (2) there would be contributing factors that cause SUV_max changes.

Case series; Level of evidence, 4.

Included were 67 knees that were treated with biplanar MOW-HTO between March 2019 and December 2020. SPECT/CT was performed immediately after surgery and at 3 months and 1 year postoperatively to determine the serial load redistribution effect of MOW-HTO. The Pearson correlation coefficient was used to evaluate the relationship between SUV_max and radiological parameters, and subgroup analyses were conducted to compare the SUV_max according to associated cartilage procedures and the weightbearing line ratio (WBLR).

The SUV_max in the medial and lateral compartments increased at 3 months but decreased at 1 year postoperatively. The load redistribution effect was most prominent in the anterior zones of the femur (medial: P = .041; lateral: P = .012). In the patella, the SUV_max decreased in both the medial and the lateral zones at all follow-up times (P < .001 for all). The SUV_max in the anterolateral and posterolateral articular zones of the femur increased with a greater preoperative WBLR (r = 0.256, P = .039; and r = 0.261, P = .036, respectively). Patients who underwent an associated cartilage procedure had a significantly higher SUV_max in the anteromedial and posteromedial articular zones of both the femur and the tibia at 1 year postoperatively (P ≤ .002 for all).

After MOW-HTO, the unloading effect in the anteromedial articular zone of the femur was the most significant. A greater SUV_max in the lateral zones of the femur was observed in cases of overcorrection. The SUV_max in the medial zones was higher postoperatively in patients with associated cartilage procedures.