Evaluation of Compartment Changes After Opening Wedge High Tibial Osteotomy Using Knee SPECT/CT

Abstract

배경: 개방형 경골 근위부 절골술은 무릎 관절염 및 내반 변형이 동반된 젊고 활동적이며, 비만이 아닌 환자에게 적합한 치료법이다. 그러나 일부 연구에서는 무릎 외측구획과 슬개대퇴 관절(PF)의 접촉 압력이 증가할 수 있다는 단점을 보고했다. 수술 후 무릎 관절의 외측 구획에 대한 부하 증가로 인해 OWHTO 이후 시간이 지남에 따라 OA 변화가 진행될 수 있다고 가정하는 것이 합리적입니다. 그러나 현재 개방형 경골 근위부 절골술 후 슬개대퇴 관절에서 관절염의 진행에 대한 합의가 없다.

대상 및 방법: 개방형 경골 근위부 절골술을 시행하는 34명의 환자 35개 무릎을 SPECT/를 사용하여 수술 전후의 변화를 평가하였다. 수술 전 및 수술 후 슬개대퇴관절 BTU (bone tracer uptake)를 하였다. 슬개대퇴관절의 BTU 변화와 관련된 인자를 분석하기 위하여 BTU 증가된 환자와 증가되지 않은 환자의 두 군으로 나누어 비교하고 다변량 분석을 시행하였다. 다변량 분석을 위하여 연령, 성별, BMI 신체질량 지수, 역학적 대퇴-경골각, 내측 근위 경골 각도, 역학적 내측 근위 경골 각도, 체중 부하 선, Blackburn-Peel ratio, 경골 후방경사각, 경골 결절-활차 홈 거리 및 congruence angle을 분석하였다.

결과: 무릎 내측 구획의 BTU는 수술 후에 유의하게 감소하였으나 (p=0.005) 외측(p=0.417)과 슬개대퇴관절 (p=0.318)은 SPECT/CT상의 평균 BTU에 유의한 변화가 없었다. 무릎 내측 구획의 BTU는 20례 (57%)에서 감소했고, 5례에서는 변화가 없었으며, 10례에서는 증가하였다. 외측 구획의 BTU는 12례에서 감소했고, 13례에서 변화가 없었으며, 10례(28%)에서 증가하였다. 슬개대퇴관절 관절 BTU는 감소한 경우가 16례, 변화가 없는 경우가 7례, 증가한 경우가 12례(34%)이었다. 근위 경골 절골술 후 슬개대퇴관절의 평균 BTU 증가와 관련된 요소는 경골 후방경사각의 증가였다.

결론: 경골 근위부 절골술 후 SPECT/CT를 사용하여 평균 BTU를 평가할 때 외측 구획 및 슬개대퇴관절에서 단기간 유의한 생체역학적 변화가 없었다. 그러나 슬개대퇴관절에서 12례 (34%)에서 평균 BTU가 증가하였다. 수술 후 경골 후방경사각의 증가는 수술 후 슬개대퇴관절의 평균 BTU증가와 관련 있을 수 있다. 경골 근위부 절골술 후 경골 후방경사각이 증가된 환자 중 슬개대퇴관절 평균 BTU의 증가가 임상결과에 나쁜 영향을 미치는지 확인하기 위하여 장기간의 추적연구가 필요하다.

주요어 : (경골 근위부 절골술, 단일광자방출단층촬영술, 슬개대퇴관절, 경골 후방경사각) 학번 : 2021-20067

Introduction Opening wedge high tibial osteotomy (OWHTO) is one of the surgical treatment options for young, physically active, and non-obese patients who have varus deformity with medial unicompartmental osteoarthritis (OA). Despite its potential benefits, extant literature has documented certain complications attributed to heightened contact pressure in the lateral compartment and the patellofemoral (PF) joint subsequent to OWHTO. Consequently, a plausible hypothesis suggests that the progression of OA may be triggered following OWHTO due to an increase in loading on the lateral compartment after the surgery. However, at present, there is a lack of consensus regarding the development of OA in the PF joint following OWHTO.

Methods Thirty-four consecutive patients (consisting of 35 knees) who underwent OWHTO for medial OA of the knee joint were included in this retrospective study. The surgical outcomes were assessed using knee clinical scores and radiographic evaluations. Additionally, biomechanical changes were evaluated preoperatively and postoperatively using knee SPECT/CT. The changes in BTU within each compartment following the surgery was analyzed based on the mean values of BTU and the proportion of patients exhibiting clinically significant BTU changes. Clinically significant BTU changes after surgery were defined as alterations exceeding 20% when compared to preoperative values. To determine the factors associated with increased BTU in the PF joint subsequent to OWHTO, patients were divided into two distinct subgroups as the increased BTU and the non-increased BTU groups. To explore the potential relationships, a multivariate regression analysis was performed, considering a set of independent variables, including age, sex, body mass index (BMI), mechanical femoro-tibial angle (MFTA), mechanical medial proximal tibial angle (MPTA), weight-bearing line ratio (WBLR), Blackburn-Peel index (BPI), posterior tibial slope angle (PTSA), tibial tuberosity to trochlear groove (TT-TG) distance, and congruence angle (CA).

Result Regarding the overall BTU changes, a significant reduction in mean BTU was observed in the medial compartment following the surgery (p=0.005). However, there were no notable changes in the mean BTU values observed in the lateral and PF joints. Specifically, within the medial compartment, BTU decreased in 20 cases (57%), remained unchanged in 5 cases, and increased in 10 cases. In the lateral compartment, BTU decreased in 12 cases, remained unchanged in 13 cases, and increased in 10 cases (28%). In the PF joint, BTU decreased in 16 cases, remained unchanged in 7 cases, and increased in 12 cases (34%). Post-surgery alignment changes were not significantly correlated with BTU changes in each compartment after surgery. However, in the subgroup analysis, which involved comparing patients with and without increased BTU in the PF joint, a significant relationship was observed between an increase in PTSA and the increase in BTU in the PF joint following OWHTO.

Conclusion Overall, the examination of mean BTU using SPECT/CT did not reveal significant biomechanical changes in the lateral and PF joints in the short-term period following OWHTO. However, it was observed that BTU increased in 12 (34%) cases in the PF joint. Moreover, a potential correlation was noted between the, increased PTSA after surgery and the increased BTU in the PF joint after surgery. A longitudinal follow-up study is essential to substantiate whether the increased BTU in the PF joint among patients exhibiting an increased PTSA has an adverse impact on adversely affect the clinical outcome s following OWHTO.

Keywords: High tibial osteotomy; Single Photon Emission Computed Tomography; Patellofemoral joint; posterior tibial slope angle Student Number: 2021-20067