Chronic Knee Dislocation: Reduction, Reconstruction, and Application of a Skeletally Fixed Knee Hinge A Report of Two Cases

A chronic knee dislocation, although extremely rare, is a difficult problem that requires complex management. There are two opposing goals after catastrophic ligament knee injuries: obtaining stability and obtaining range of motion. Achieving both of these goals can be very diffi-cult.1,2,5,7,10,12 Multiple ligament reconstructions using allograft tissues are currently the recommended method of dealing with acute unstable knee injuries.1,4,11 Despite modern techniques, recurrent knee laxity or stiffness can be problematic.1,2,5,7,10,12 These problems are amplified in the case of a chronic fixed dislocation. Recently, there was a report of delayed reduction without reconstruction 24 weeks after a traumatic posterior knee dislocation.3 The patient was treated with open reduction, mainte-nance of the reduction with Steinman pins, and placement of the limb in a cylinder cast for 12 weeks. Reconstruction was not attempted because of compromised articular sur-faces. The final result yielded a range of motion from 5° to 40°. To reduce the chronically dislocated knee, complete re-leases of scar tissue and capsule are required, placing increased stresses on the reconstruction. In an attempt to decrease stress on the newly reconstructed ligaments and still allow knee motion, a skeletally fixed hinge system can be used. Because of the degree of instability, a limited period of hinge application is thought to be helpful in reestablishing stable motion. For acceptable use, the hinge should provide an anatomic range of motion, offer ease of application, and be tolerated by the patient. We are reporting two cases of chronic, fixed posterior knee dislocations. Both were treated with extensive re-lease and allograft ligament reconstruction with the addi-tion of a skeletally fixed knee hinge for the first 6 weeks