Surgical management
MB-PKAs, chondropathy
OSTEOPHYTES, CHONDROPATHY
Magnetic resonance imaging (MRI) was assessed pre-operatively to confirm the anatomical integrity of cruciate and collateral ligaments in all patients, and to exclude chondropathy of the lateral knee compartment. All MB-PKAs were performed with the same minimal invasive surgical approach. All the patients were placed in a supine position on a standard operating table after administering spinal anaesthesia. A tourniquet was applied to the proximal thigh on the operative side and inflated to 300 mm Hg. The operated leg was placed on thigh support with the hip flexed to about 30° degrees and the leg pendant. A medial small parapatellar incision was made; the patella was not dislocated avoiding, as much as possible, any damage to the synovial reflections of the suprapatellar pouch. The margins of the medial tibial condyle were exposed and cleared, taking care not to release too much of the soft tissue. The medial meniscus was removed. The osteophytes were removed from the tibia, femur and the intercondylar notch. The anterior cruciate ligament (ACL) status was checked. First, the tibial cut was made sagittal as near to the ACL insertion as possible. However, precautions were taken not to cut ACL fibres. The saw was parallel to the anatomical axis of the tibia and not tilted medially, laterally, anteriorly or posteriorly. The femoral cuts were then taken using the intramedullary guide and microplasty instrumentation. The flexion–extension gap balancing was measured in 20° of flexion. The extension gap is usually less than 4 mm: if the thinnest (1 mm feeler gauge) cannot be inserted, the gap is assumed to be 0 mm. Subtract the extension gap from the extension gap to calculate additional bone removal. For instance, if the extension gap measured 4 mm and the extension gap 1 mm, then the amount of bone to be milled is 3 mm. To achieve this, insert a 3 spigot and mill until the cutter will not advance further. After the final sizing, the implants were cemented and an appropriately sized mobile poly insert was used [All FB-PKAs were performed with the same minimal invasive surgical approach. All patients were placed in a supine position on a standard operating table after the spinal anaesthesia had been induced and the knee and the ipsilateral hip were freely mobile without the use of a tourniquet. A good exposure was obtained with skin incision starting from the medial margin of the patella to a point approximately 3 cm distal to the joint line. As reported by the surgical technique, a good ratio is usually an incision 2/3 above and 1/3 below the joint line. Further, a deep exposure was achieved with a parapatellar approach through the subcutaneous tissues to the joint capsule and the patella was laterally dislocated. A routine inspection of the patellofemoral and lateral compartment was conducted and the ACL status was checked. The medial and intercondylar osteophytes were removed, and an anterior tibial pre-cut was performed to get adequate posterior and articular view and access. In all cases, the Zimmer-Biomet PPK system (Zimmer, Warsaw, Indiana, USA) was implanted using the corresponding instrumentation, extramedullary tibial guide and femoral and tibial cutting guides. All components were cemented using Refobacin® Bone Cement 