Efficacy of various forms of fixation of transverse fractures of the patella.

To determine whether any of the commonly used wiring techniques are rigid enough to allow early motion in the treatment of transverse fracture of the patella, the patellae of twenty-five fresh cadaver knees were fractured transversely and fixed using the following techniques: circumferential wiring, tension-band wiring, Magnusson wiring, and a modification of tension-band wiring. The knees were mounted in a machine capable of measuring quadriceps force, flexion angle, and fracture separation simultaneously. The knees were extended from 90 to zero degrees by applying tension to the quadriceps tendon with the force of gravity as the only resistance, and separation of the fracture fragments was measured first with the retinaculum unrepaired and then again with the retinaculum repaired. Separation of the fracture fragments was much less with the Magnusson wiring and modified tension-band wiring than with circumferential wiring or standard tension-band wiring. The retinacular repair was found to contribute to stability; however, this seemed most important in the less rigid repairs. We concluded that if early motion is to be used in treating transverse fractures of the patella, techniques in which the wire is anchored directly in bone should be used and the retinaculum should be repaired.