The Modern Indications for Medial UKA the “Oxford Philosophy” Deciphered

UKA is an effective treatment of avascular necrosis localised in a single compartment, but only 2–6% of knee replacement surgery patients are eligible for it due to age, weight, level of activity, pain, joint mobility, patellar subchondral exposure, and radiological chondrocalcinosis. The Oxford team of John Goodfellow and John O’Connor has validated broader patient selection criteria that can increase the number of UKA by widening the indications and/or ignoring certain “traditional” contraindications. The anterior condylar shell is partially retracted or in conflict with osteophytes, preventing correction of the varus deformity and contributing to permanent flexion deformity. Postoperative stretching of the medial collateral ligament prevents its retraction, making the deformity reducible during a forced valgus movement at 20°. UKA is possible in the setting of femoral osteonecrosis, but vigilance is recommended due to increased risk of infection and loosening of the prosthesis. Preoperative MRI is necessary to confirm the diagnosis and assess the extent of necrosis. Medial tibiofemoral OA after tibial osteotomy (HTO) can be treated with medial UKA. Bicompartmental UKA and simultaneous patellofemoral arthroplasty are rare. UKA is an attractive alternative to TKR in the setting of deterioration of the medial tibiofemoral compartment after an initial procedure. UKA should no longer be considered a contraindication due to high body weight, young age, major physical activity, radiological chondrocalcinosis, patellofemoral damage, medial subluxation of the tibia, and osteophytes in the lateral plateau. Younger patients may enable better mobility without significantly improving functional scores. UKA should not be seen as a simpler alternative to TKR due to age and physical activity. Flexion deformity is not a contraindication, but the status of the ACL and causes must be correctly assessed. The patellofemoral joint is not a contraindication to medial UKA, and the presence of anterior pain does not predict an unfavourable result. Unjustified contraindications are responsible for limiting the use of UKA in the treatment of knee anteromedial OA. UKA can be performed on a knee with a nonfunctional anterior cruciate ligament due to good functional results and low morbidity in elderly patients. Three nosological entities are advanced anteromedial OA, posteromedial OA, and medial tibiofemoral OA. UKA can be proposed as an alternative to TKR for PMOA, but long-term survival remains little documented and should be reserved for experienced surgeons. Widening the selection criteria for UKA-eligible patients is necessary to limit the rate of revision surgery. AMOA is the main indication for medial UKA, but widening the indications to marginal indications is not a good method of increasing the volume of procedures. UKA can increase the rate of use and annual volume in a safe manner by reducing the list of “traditional” contraindications, such as high weight, young age, major physical activity, radiological chondrocalcinosis, patellofemoral damage, medial subluxation of the tibia, and osteophytes in the lateral plateau.