[S-ROM Modular THR System -Three and Half Years of Experience.]

PURPOSE OF THE STUDY Presentation of the first 3,5-year experience with the application of S-ROM system in total hip arthroplasty. MATERIAL A retrospective study evaluating 33 patients (14 men, 19 women), average age 57 years (25-84 years) operated on in the period betwen December 1996 and June 2000. In 5 cases we performed primary implantation and in 28 cases revision surgery. Indications to primary surgery included once primary osteoarthritis, twice postdysplastic osteoarthritis and twice trauma. Of revision surgeries, there were 19 cases of aseptic loosening, 8 cases of septic loosening and once malposition of the stem. In 10 cases the revision surgery consisted in a mere replacement of the stem, complete replantation including the acetabular cup was performed in 18 cases. In 24 cases it was the first revision of the stem, in 4 cases the second revision. In 19 patients the revised stem was originally cemented, in 8 patients cementless and in 2 patients it was impossible to identify the original type of the stem. Acetabular cup was replanted in 18 cases with two exceptions by means of a cementless component. METHOD The evaluation concentrated mainly on peroperative and postoperative complications and symptoms of loosening.The follow-up ranged between 4 and 45 months with the average of 30 months. Twenty-four patients were followed for more than 2 years, 16 patients for more than 3 years, 4 patients for less than one year. OUTCOMES We recorded in total 15 complications, of which 8 peroperative and 6 postoperative. Of 8 peroperative complications we evaluated 6 cases as specific for S-ROM. In 5 cases the introduction of the stem resulted in the calcar split which was treated by wire cerclage. In 1 case when we applied in the revision surgery a longer straight stem the tip of the stem got to a close contact, even perforated the anterior cortex of the femoral shaft. A nonspecific complication was represented by a spiral fracture of femoral shaft during the perforation of the pedestal formation below the tip of the original cementless loosened stem. The fracture was treated by a plate. For a similarly non-specific complication we consider partial reaming of the medial cortex during the revision surgery of a loosened cemented stem. Both the calcar splits and the fracture of the shaft healed without any complications. The cases of the perforation of the anterior cortex and the above mentioned reaming of the medial cortex were not associated with any subjective complaints or objective problems, either. Six postoperative complications included three dislocations (twice treated by open reduction), one paraarticular heterotopic ossification (Brooker III type), once pain in the thigh and once recurrence of the infection. In 24 patients with the follow-up longer than two years we did not record any signs of loosening or localized osteolysis or signs of metal wear betwen the stem and the conical sleeve. In 30 cases we evaluate the result of the operation as very good. As a failure we consider the case of a recurring dislocations, the case of paraarticular ossifications and thigh pain and the case of the recurrent infection. DISCUSSION Our results prove the existing literary data on good medium-term results of the application of S-ROM system, mainly in case of revision surgery. Its specific complication is a peroperative calcar (Adam's arch) split and perforation of the anterior diaphyseal cortex when using the long stem. CONCLUSION S-ROM represents a perspective system for revision surgeries. It is contraindicated in case of extensive defects of the proximal femur which do not allow to anchor the conic sleeve and in case of severe osteoporosis.

total hip arthroplasty, S-ROM, revision surgery.