Initially, closed reduction is advised as the treatment for acute PTFJ dislocation.11,19,24 It involves placing the knee in 80°to 110° of flexion to relax the biceps femoris and LCL, then applying an appropriate force to the fibular head in a direction opposite the displacement.11,24 An audible pop is often heard as the fibula reduces back into normal alignment. Stability of the reduction and stability of the knee should be determined with respect to both posterolateral structures and the LCL after reduction.11 Anterolateral dislocations are usually easier to reduce, as a posteromedial or superior dislocation can result in the fibular head being perched on the lateral tibial ridge, and held by the LCL.11
Calabró and colleagues27 described a new, simple, and safe alternative technique of closed reduction of an anterior dislocation if the classical method fails. This technique relies on ligamentotaxis and a dynamic counteraction between muscles and ligaments to reduce the joint. The patient flexes the knee >90° while the physician applies a counterforce to the heel with the palm. Simultaneously, gentle direct pressure should be applied to the fibular head to move it toward the lateral tibial ridge. With a relaxed LCL, the biceps femoris tendon will actively reduce the proximal fibular head back into its correct anatomic orientation.27
When a closed reduction in an awake patient has failed, a reduction under sedation or anesthesia should be performed. If that fails, an open reduction should be performed. Following an open reduction, the joint is stabilized with Kirschner wires, bioabsorbable pins, or cortical screws.24-26,28 The torn capsule and any injured ligaments should also be primarily repaired. After approximately 6 weeks, the stabilization hardware may be removed.24,25
Acute posteromedial dislocations are treated similarly to anterolateral dislocations; however, open reduction and repair of the capsule and ligaments are more frequently required.10 Superior dislocations are also more frequently reduced by open methods, sometimes dictated by open treatment of associated tibia or ankle fracture.10 Damage to any structure of the posterolateral knee as a result of acute PTFJ injury should be repaired, as this has been associated with better outcomes.14
PTFJ dislocation and tibia fracture can occur together, and in a retrospective study conducted by Herzog and colleagues29 the authors recorded the incidence of PTFJ dislocation as 1.5% of operative tibial shaft fractures and 1.9% of operative tibial plateau fractures. Haupt and colleagues30 also conducted a retrospective study in which the authors recorded the incidence of PTFJ dislocations in 1.06% of all tibial shaft fractures in their series. In both studies combined, all except 1 PTFJ dislocation had been caused by high-energy trauma.29,30 In the case of PTFJ dislocation with tibial shaft fracture, intramedullary nailing of the tibial shaft fracture followed by open reduction of the PTFJ with 1 or 2 positioning screws just below the PTFJ has yielded satisfactory results.30 The positioning screw should be removed 6 weeks post-operation to prevent PTFJ arthrodesis and patients should be supported in full weight-bearing.30 An illustrative case report from our institution is shown in Figure 3.
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