Changes in the patellar height following open wedge high tibial osteotomy

Abstract

Background: Genu varum of the knee is a predisposing factor for osteoarthritis of the medial femoro-tibial compartment. High tibial osteotomy is the surgery of choice for such patients. Patello-femoral abnormalities have a negative effect on the prognosis of high tibial osteotomy. Both pre-existing patellar pain and patello-femoral joint space narrowing are reported to be more severe after high tibial osteotomy. The idea of high tibial osteotomy is to unload an overloaded compartment, to slow down the progress of osteoarthritis and to allow healing of articular cartilage. Aim of this work: was to assess and analyze the changes in patellar height after medial open wedge high tibial osteotomy. Patients and Methods: This was a prospective and retrospective case series study performed in the period from 2018 till 2019 on 30 patients at Kafr El Sheikh University Hospital. The age ranged between19-54 years. There was 16 male (53.33%) and 14 females (46.66%). In 19 knees the left side was affected (63.33%), 11 knees (36.66%) on the right side and three bilaterally (10%). Results: After medial opening wedge high tibial osteotomy and measurement the patellar height preoperatively and postoperatively, we found the patellar height on the Caton-Deschamps ratio method the patella was lowered in 22 cases, remained constant in 8 cases. Key-words: Genu varum, Patello-femoral joint, High tibial osteotomy. Introduction: Knee osteoarthritis (OA) is a disease common in older adults that can result in significant disability because of pain, stiffness, and loss of joint motion. Current treatment is aimed at minimizing pain, maintaining or improving joint mobility, and decreasing functional impairment. Although the pathogenesis of knee OA is not well understood, biomechanical stresses that affect the articular cartilage and a Department of orthopedic surgery, Faculty of medicine , Kafr elsheikh University, Egypt. b Department of orthopedic surgery Benha faculty of medicine, Benha University, Egypt. Correspondence to: Abd Al Rahman Z. Al Shewehi, Department of orthopedic surgery, Faculty of medicine , Kafr elsheikh University, Egypt . Email: [email protected] Received: 16 August 2019 Accepted: 17 May 2021 Changes in the patellar height following open wedge high tibial osteotomy, 2021 67 subchondral bone have been implicated as important inciting factors. [1-3] Varus angulation deformity results in medial compartment knee OA and contribute to the progression of OA by causing increased load to the medial knee compartment, with subsequent damage to the articular cartilage and subchondral bone in that area .[4] Medial opening wedge osteotomy is a relatively simple procedure that involves a single osteotomy and few dissections. The technique does not necessitate either a fibular osteotomy that has been associated with neurovascular complications or bone resection of lateral tibia. Accordingly, the normal anatomical tibial bone shape is maintained after the procedure, which allows for conversion to TKA. The level of correction can be identified and adjusted intraoperatively on coronal and sagittal planes and shortening of lower limbs can be prevented. [5] High tibial osteotomy is the surgery of choice for such patients. Patello-femoral abnormalities have a negative effect on the prognosis of high tibial osteotomy. Both pre-existing patellar pain and patellofemoral joint space narrowing are reported to be more severe after high tibial osteotomy. [6-7] The idea of high tibial osteotomy (HTO) is to unload an overloaded compartment, to slow down the progress of OA and to allow healing of articular cartilage. To obtain successful results in HTO not only requires the application of a good surgical technique but also depends on appropriate patient selection. [8-9] Description of this technique is dating back to the 50s, with Jackson and Dehaven. However, it was not until the 70s, with the publications of Conventry and Insall, that high tibial osteotomy became common practice. [9-11] At that time, closing wedge osteotomies were performed, despite the greater technical difficulty and risks involved, as there were no fixation materials available that could enable opening wedge osteotomy. Only after the development of medial wedge plate fixation that opening wedge osteotomy became applicable. [12] Research regarding the effects of HTO on the patellofemoral joint has shown an alteration of patellar height. The change in patellofemoral indices, patellar height, patellar tilt and patellar shift can be a potent cause of deranged patellofemoral kinematics and subsequent patellofemoral arthrosis. Patellar infera is associated with a decreased range of motion, a decreased lever arm, extensor lag, anterior knee pain, increased energy expenditure and a Benha medical journal vol. 38, special issue (orthopedic surgery), 2021 68 possibility of rupture of patellar or quadriceps tendons. [13-15] The principal causes of change of patellar height with medial opening wedge high tibial osteotomy are known to be from patellar ligament scarring, distal transfer of the tibial tubercle and the elevation of tibiofemoral joint line. [16]