Abstract
BACKGROUND: Mechanical axis deviation (MAD) disrupts the natural force distribution within the knee joint. MAD malalignment imparts atypical tibial plateau loading forces, which can cause painful knee cartilage degeneration, abnormal gait, and reduced activity and mobility(1). A medial opening-wedge high tibial osteotomy corrects varus MAD for deformities centered in the proximal tibia, reducing medial knee compartment stress, which often improves pain, function, and self-image(2). DESCRIPTION: Surgical planning starts with a history to understand the patient symptoms, potential etiologies, and goals. Physical examination assesses standing and walking coronal alignment, investigates any rotational concerns, and evaluates lower-extremity joint motion. A bilateral weight-bearing hip-to-ankle anteroposterior radiograph is used to measure the MAD, lateral distal femoral angle, and medial proximal tibial angle, which determine the center of rotation and angulation (CORA). Weight-bearing anteroposterior, flexion posteroanterior, and lateral knee radiographs are used to assess arthrosis and patellar tracking(3,4). The key steps include a medial exposure of the proximal tibia, biplanar osteotomy in the proximal metaphyseal tibia (1 plane is the sagittal plane to impart angular correction and the other plane is parallel and posterior to the patella), opening of the wedge, fixation with plate and screws, and skin closure. ALTERNATIVES: Nonoperative treatments such as bracing, physical therapy, joint injection, and activity modification may palliate symptoms but do not correct the deformity. Distal femoral osteotomies are indicated when the deformity center of rotation and angulation exist in that location(5). Hexapod frames are more appropriate for multiplanar or large deformities (>11°), which may benefit from gradual correction(3,6). A lateral closing-wedge high tibial osteotomy can achieve similar realignment but puts the common peroneal nerve at risk because of the surgical approach, and there is limited visualization of the tibia because of fibular obstruction(2,7,8). Skeletally immature patients with sufficient growth remaining may be partially or fully managed with lateral proximal tibial hemiepiphysiodesis(9). Total knee arthroplasty (TKA) can address coronal plane deformities and joint arthritis but is joint-ablative, and often patients are counseled to reduce their activity intensity and beware of periprosthetic joint infection(10). RATIONALE: Untreated MAD predisposes to early degenerative osteoarthritis and can impair gait, resulting in subpar activity levels and reduced quality of life. Medial opening-wedge high tibial osteotomy corrects proximal tibia-based varus malalignment; normalizes knee joint loading, which should alleviate pain; and preserves the native knee joint, which permits higher activity and lower infection concern than TKA. The medial approach is technically easier and safer than a lateral closing-wedge osteotomy. Medial opening-wedge high tibial osteotomy offers a joint-preserving correction of alignment and is especially suitable for young or active patients aiming to delay or avoid joint replacement surgery, imparting pain relief and allowing improved mobility and quality of life(1). EXPECTED OUTCOMES: On osteotomy union, patients should feel improvement of pain and have a more balanced gait(1,8,11). Medial opening-wedge high tibial osteotomy is a joint-preserving operation that can prevent the need for a TKA without excluding it as a future option. IMPORTANT TIPS: Clearly agree upon expectations and correction goals with patient preoperatively.Measure radiographs carefully preoperatively to correctly identify the CORA and amount of correction.Support the operated leg at all times to avoid uncontrolled fracture after osteotomy.Check alignment carefully intraoperatively, with patella facing directly upwards.Avoid postoperative fracture by limiting weight-bearing to 50 lbs (22.7 kg) for 6 weeks. ACRONYMS AND ABBREVIATIONS: LDFA = lateral distal femoral angleMOWHTO = medial opening-wedge high tibial osteotomyMPTA = medial proximal tibial angleCORA = center of rotation and angulationMVA = motor vehicle accidentBL = bilateralFx = fracturePT = physical therapyROM = range of motionK-wire = Kirschner wire.