Summary High Tibial Osteotomy (HTO) is a surgical procedure that is performed to correct angular deformities of the knee to prevent development or progression of unicompartmental osteoarthritis. It is predominately done to correct for varus deformities in young patients but can also be done to correct valgus deformities. Contraindications include inflammatory arthritis, flexion contracture > 15 degrees, bicompartmental osteoarthritis, and ligamentous instability. Epidemiology Primary or secondary medial knee arthrosis is the most common indication Isolated lateral compartment osteoarthritis is much less common Etiology Use predominately done for varus deformities less common for valgus deformities Angular deformity in the knee leads to abnormal distribution of weight bearing stresses can accelerate wear in medial or lateral compartments of the knee and lead to degeneration HTO is commonly combined with cartilage restoration procedures to provide better mechanical environment for biologic repair Anatomy Mechanical axis of lower extremity can be assessed by drawing straight line from center of femoral head to the center of the ankle joint line axis should pass just medial to the medial tibial spine Classification Varus vs Valgus alignment Presentation Symptoms pain on medial or lateral side of knee Exam knee malalignment Imaging Radiographs standing alignment hip-to-ankle films show knee malalignment using mechanical axis line Studies Treatment Indications young, active patient (<50 years) in whom an arthroplasty would fail due to excessive wear healthy patient with good vascular status non-obese patients pain and disability interfering with daily life only one knee compartment is affected compliant patient that will be able to follow postop protocol General contraindications inflammatory arthritis obese patient BMI>35 flexion contracture >15 degrees knee flexion <90 degrees procedure will need >20 degrees of correction patellofemoral arthritis ligament instability varus thrust during gait Valgus-producing tibial osteotomy Goals unload the involved joint compartment by correcting tibial malalignment A medial unloader brace can be used for therapeutic and diagnostic purposes. If a patient benefits from the brace, they are likely to benefit from surgery. maintain the joint line perpendicular to mechanical axis of the leg Indications can be done for varus knee with medial compartment degeneration (more common) best results achieved by overcorrection of the anatomical axis to 8-10 degrees of valgus Contraindications narrow lateral compartment cartilage space with stress radiographs loss of lateral meniscus lateral tibial subluxation >1cm medial compartment bone loss >2-3mm varus deformity >10 degrees Varus-producing tibial osteotomy Used less commonly than distal femoral osteotomy produces obliquity of the tibiofemoral joint line Goals unload the involved joint compartment by correcting tibial malalignment maintain the joint line perpendicular to mechanical axis of the leg Indications can be done for valgus knee with lateral compartment degeneration deformity should be <12 degrees or else the joint line will become oblique Contraindications medial compartment arthritis loss of medial meniscus distal femoral osteotomy better if lateral femoral condyle hypoplasia present adjunct to soft tissue reconstructive surgeries (ACL/PCL/MACI) when there is coronal malalignment Technique Lateral closing wedge technique wedge of bone removed with tibia via an anterolateral approach ORIF of wedge has advantages more inherent stability allows for faster rehab and weight bearing no required bone grafting Medial opening wedge technique transverse bone cut made in proximal tibia, and wedged open on medial side ORIF of wedge has advantages of maintaining posterior slope increasing slope increases stress on ACL, while decreased slope alleviates stress on the ACL avoids proximal tibiofibular joint avoids peroneal nerve in anterior compartment Focal dome osteotomy (concavity proximal) the center of the dome is located at the center of rotation of angulation (CORA) has advantages corrects limb alignment with the least translation of bone ends least translation of anatomical axis minimal shortening Complications Recurrence of deformity 60% failure rate after 3 years when failure to overcorrect patients are overweight Loss of posterior slope Patella baja refers to a shortened patellar tendon which decreases the distance of the patellar tendon from the inferior joint line can be caused by raising tibiofemoral joint line in opening wedge osteotomies can be caused by retropatellar scarring and tendon contracture can cause bony impingement of patella on tibia Compartment syndrome Peroneal nerve palsy more common in lateral opening wedge osteotomy and lateral closing wedge osteotomy minimal risk in medial opening wedge osteotomy Malunion or nonunion Prognosis Varus-producing high tibial osteotomy success rate is 87% in 10 years Valgus-producing high tibial osteotomy success rate is 50-85% in 10 years