IntroductionThe inside-out technique is a safe and reproducible method to effectively correct a fixed varus-flexion deformity during total knee arthroplasty by performing a posteromedial capsular release and so-called pie-crust lengthening of the superficial medial collateral ligament (sMCL).
Step 1: Preoperative PlanningAnalyze preoperative radiographs as a key step in planning the surgery for the required amount of osseous cuts and soft-tissue release.
Step 2: ExposureObtain adequate exposure for proper visualization and assessment.
Step 3: Tibial and Femoral CutsAdequate bone cuts with proper alignment are an essential step of this technique.
Step 4: Posteromedial CapsulotomyThis is the most important step for extension balancing in knees with flexion contracture; the posteromedial aspect of the capsule in varus deformity should be safely incised at the level of the tibial cut.
Step 5: Pie-Crusting of the sMCLPerform pie-crusting followed by serial manipulations in a controlled manner to avoid overrelease of the sMCL.
Step 6: Flexion Gap BalancingThis is a key step for proper balancing, femoral sizing, rotation, lateralization, and patellofemoral tracking.
ResultsFrom October 2006 to December 2009, thirty-one consecutive patients (thirty-four knees) with a severe fixed varus-flexion deformity (varus alignment of ≥15° and flexion contracture of ≥5°) underwent total knee arthroplasty with the inside-out technique.
What to Watch ForIndicationsContraindicationsPitfalls & Challenges