VERY HIGH SURVIVAL RATE OF THE CEMENTLESS SPOTORNO STEM IN LONGTERM ANALYSES OF TOTAL HIP ARTHROPLASTY.

Abstract

In cementless Total Hip Arthroplasty (THA), some discussion persist in different continents, weather straight double tapered stems providing proximal metaphyseal fixation are preferable to more diaphyseal cylindrical fixation designs.

With the objective of studying the grade of loosening of a straight double tapered stem and its survival rate, the authors analysed 257 THA with implanted Spotorno stems, followed up for a maximum of over 18 years (221 months), with an average of 110±57 months. The age of patients was 62±10 years in average, ranging from 18 to 86. Demographic data is analysed including, sex, height, weight and BMI.

Main diagnosis was Primary Degenerative Osteoarthritis in 56% and Avascular Necrosis in 13% of all patients. Other diagnosis occurrence is presented, as well as the affected side, type of cup, head and stem size distributions.

Clinical and functional evaluation of the THA showed Very Good and Good patient satisfaction grading in 78% of the cases and the average Harris Hip Score was 87, ranging from 49 to 98. In the Radiological evaluation, stem positioning, migration, osteolysis and distribution of radiolucent lines are quantified and described.

79 patients included in this study with 84 THA, died or were lost after a minimum of five years of complete clinical and radiological follow up. The most significant early and late complications of THA are presented and commented. THA requiring revision of the cup or stem for any cause, were 1 severe deep infection (0.4%), 4 cups loosened and migrated but not requiring revision of the stems (1.6%), 1 femoral osteolysis and loosening (0.4%) and 2 late traumatic femoral fractures (0.8%). From these, considering stem survival alone, a total of four stems (1.6%) underwent femoral revision as previously described, one due to infection, one due to loosening and two due to femoral fractures. Kaplan-Meyer cumulative survival analyses of the THA show a Spotorno stem survival rate of 98.4% at 18 years, with a confidence interval of 95%.

In the experience of the authors, the Spotorno double tapered straight stem provides excellent clinical results, with high survival rate at longterm evaluation. The design of the stem allows for immediate progressive weight bearing without significant migration or thigh pain. Femoral proximal osteolysis or radiolucent lines are almost always associated with wear or loosening of the cup, that very often allow for revision of the cup without the need for revision of the stem.