Stem revision. Classification and treatment

The goal of every hip revision is to restore as much function as possible. Frequent problems are defects of the load-carrying bony substance and funct ional deficits due to trochanteric avulsions, abductor insufficiencies, and lesions of the superior gluteal nerve. Disturbed functions of these im por ta nt structures may lead to unsatisfactory results with high dislocation r ates and limping. Various femoral defect classifications differ in their description of the l esion as well as in their proposed therapeutic approach. Significant differ ences exist in the field of allograft use. Among others, the AAOS, SO.F.C.O .T,and Paprosky's classifications are described. Our own easy to use altern ative classification is introduced which takes into consideration the fixat ion principle of the new stem. It thus helps to select the type of implant and offers a guideline for technical modalities. A Type 1 defect allows a revision with a component suitable for a primary c ase. Type 2 defects can be treated with a short revision stem exceeding the length of the revised stem. Type 3 defects are treated with a "load-sharin g" concept where an optimized metaphyseal fill and a cylindrical shape dist ally share the axial and torsion loads. Type 4 defects are reconstructed wi th a combination of a revision stem and an allograft.