CLINICAL-RESULTS OF THE MIDSTEM POROUS-COATED ANATOMIC UNCEMENTED FEMORAL STEM IN PRIMARY TOTAL HIP-ARTHROPLASTY - A 5 TO 9-YEAR PROSPECTIVE-STUDY

The clinical and radiologic results of an inclusive series of 60 patie nts (70 hips) who had primary total hip arthroplasty using the porous- coated anatomic (PCA) midstem femoral prosthesis was prospectively stu died. The midstem component features a proximal circumferential porous bead coating similar to the PCA primary stem; but increased proximal thickness, increased length, and a distal anterior curve for additiona l rotational stability. The mean Harris Hip Score rose from 39.5 point s before surgery to 91.3 points at a minimum follow-up of 5 years (ave rage, 69 months); 88% were good or excellent. Moderate or severe thigh pain on a visual analogue scale was reported by 30% of cases, and was more common in women. Radiographic analysis indicated preservation of proximal bone stock and bony ingrowth in 87%, but stem subsidence in 9%. One stem has been revised for subsidence and thigh pain (1.4%). an d one stem is radiographically loose, but the patient refuses surgical revision. Endosteal osteolysis vc as rarely seen (2.8%) and was benig n in appearance. Acetabular components used included 63 nonmodular PCA metal-backed cups and 7 hemispherical porous ingrowth cups fixed with screws. One PCA cup was revised for loosening (1.4%), and one is radi ographically loose but stable (1.4%). Only one cup exhibited an area o f osteolysis. Ar this intermediate follow-up the clinical outcome of t he midstem component is stable and excellent. The radiographic results appear superior to the PCP, primary stem, with a lower incidence of s tem subsidence and osteolysis.;The prevalence of thigh pain is a conce rn and we recommend regular follow-up of patients with the midstem fem oral implant, and the use of a visual analogue thigh pain scale when a ny femoral prosthesis is evaluated.