PMC8020459_01
Preoperative long-standing anteroposterior radiograph of the lower extremity.
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A long-standing anteroposterior radiograph confirmed 16  of genu valgum deformity with the mechanical axis passing through her lateral tibial plateau (Figures 1 and 2).
Preoperative lateral radiograph of the right knee.
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A long-standing anteroposterior radiograph confirmed 16  of genu valgum deformity with the mechanical axis passing through her lateral tibial plateau (Figures 1 and 2).
Patellar dislocation on preoperative CT scan.
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A CT scan evaluation revealed a narrow medullary cavity of the distal femur as well as patellar dislocation and severe osteoarthritis of the knee with complete loss of the lateral compartment joint space (Figure 3).
Intraoperative photography showing the patella located on the lateral aspect of the lateral femoral condyle (medial border of patella was marked with two stitches).
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The patella was palpable on the lateral aspect of the lateral femoral condyle (Figure 4).
Intraoperative photography showing the patella centrally placed in the groove of the femoral component.
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The definitive components were cemented (Figure 5).
Diagrammatic representation of the soft tissue release performed to correct congenital dislocation of the patella. (A) Step 1 - Vertical limb of the medial incision (solid red line) made along the medial edge of the patellar tendon to the tibial tubercle; Step 2 - Horizontal limb of the medial incision (dashed red line) taken along the inferior margin of the vastus medialis; Step 3 - Blunt dissection of the vastus medialis from the medial intermuscular septum (dotted red line) approximately 10 cm proximal to the adductor tubercle; Step 4 - Lateral release of the patellar retinaculum (dashed blue line) performed from inside the knee joint staying lateral to the vastus lateralis; Step 5 - Release of the vastus lateralis (solid blue line) from the lateral intermuscular septum and anterior femur by submuscular dissection. Schematic diagram of the extensor mechanism realignment. (B) Step 1 - Temporary fixation of the medial retinaculum flap brought laterally and fixed to the superolateral aspect of the patella; Step 2 - Evaluation of the patellar tracking; Step 3 - Resection of the redundant pouch of the medial retinaculum flap pulled over the patellar tendon; Step 4 - Distal medial repair with the suture of the medial capsule and the patellar ligament in a secure manner; Step 5 - Suture of the proximal part of the medial retinaculum flap (pulled over the anterior aspect of the patella) to the extensor apparatus; Step 6 - The medial capsular suture completed proximally.
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Schematic diagrams present a step-by-step description of the surgical technique (Figure 6A and B).
Postoperative radiograph of the right knee: (A) anteroposterior and (B) lateral.
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Anteroposterior and lateral radiographs were obtained, the patella was clearly seen on the lateral view (Figure 7A and B).