Increased patellar bone tracer uptake in preoperative SPECT/CT before medial opening high tibial osteotomy correlates with inferior clinical outcome

Abstract

Purpose The purpose of this study was to investigate whether specific bone tracer uptake (BTU) patterns on preoperative SPECT/CT could predict which patients with varus alignment and medial overload would particularly benefit from medial opening-wedge high tibial osteotomy (MOWHTO). It was the hypothesis that an increased preoperative BTU relative to the reference BTU of the femur on SPECT/CT in the lateral and patellar compartments of the knee are predictive factors for inferior clinical outcome and that the clinical outcome correlates with the extent of alignment correction. Methods Twenty-three knees from 22 patients who underwent MOWHTO for medial compartment overload were investigated preoperatively using Tc-99m-SPECT/CT. BTU was quantified and localised to specific joint areas according to a previously validated scheme. Pre- and postoperative mechanical alignment was measured. Clinical outcome was assessed at a median of 24 months (range 11–30) after MOWHTO by collecting the WOMAC score. Results Significant correlations between BTU in the patellar area and the total WOMAC score and its subcategories pain and stiffness were found. Thus, BTU in the 1sPat area (superior lateral patellar compartment) correlated with total WOMAC (rho = 0.43, p = 0.04), pain subcategory (rho = 0.43, p = 0.04), and stiffness subcategory (rho = 0.59, p = 0.003). No significant correlations were found between alignment correction, age, gender and WOMAC. Conclusion This study highlights the role of preoperative SPECT in modern knee surgery to obtain information about the loading pattern on different compartments of the knee. Despite the limited number of participants, the present study shows that a preoperative SPECT/CT scan can help the treating surgeons to identify patients who may be at risk of inferior clinical outcome if an MOWHTO is considered, as an elevated BTU in the patellar region on preoperative SPECT/CT appears to be a potential risk factor for postoperative pain and stiffness. Level of evidence Level III.

Preoperative joint line convergence angle correction is a key factor in optimising accuracy in varus knee correction osteotomy

“…This issue has been controversial, and additional preoperative assessments may be necessary to anticipate the clinical outcome [36]. However, in the authors' opinion, an accuracy of ± 1.5°, as mentioned before, seems necessary when performing varus correction osteotomies because biomechanical studies have observed a signiicant load shift beginning at 3° of varus [4,8].…”

“…The clinical relevance of overcorrection was shown in a study by Hohloch et al, who demonstrated in a comparative study of HTOs aiming for postoperative 50–55%, 55–60% and > 60% mTFA intersection significantly better results in terms of Lysholm Score and Knee Injury and Osteoarthritis Outcome Score (KOOS) for a 50–55% intersection [ 13 ]. This issue has been controversial, and additional preoperative assessments may be necessary to anticipate the clinical outcome [ 36 ]. However, in the authors’ opinion, an accuracy of ± 1.5°, as mentioned before, seems necessary when performing varus correction osteotomies because biomechanical studies have observed a significant load shift beginning at 3° of varus [ 4 , 8 ].…”

Cartilage regeneration is related to superior mid‐term patient‐reported outcomes after open‐wedge high tibial osteotomy

“…In addition, only the cartilage status of the medial compartment was assessed in this study. Schelker et al [29] reported that increased patellar bone tracer uptake in preoperative SPECT/CT before OWHTO correlates with inferior clinical outcomes. Not only should the medial compartment be considered, but preoperative conditions, the patellofemoral joint and the lateral compartment must also be assessed in future studies.…”

Larger bone marrow lesion volume before medial open-wedge high tibial osteotomy correlates with better improvement of clinical scores in patients with knee osteoarthritis

“…Sixth, the effect of the patellofemoral joint on the clinical outcomes was not evaluated. A recent study reported inferior post‐operative outcomes in patients with increased patellar bone tracer uptake on pre‐operative SPECT/CT [26]. BML in the patellofemoral joint might affect clinical outcomes after HTO.…”