Yasushi Oshima and Joseph F Fetto
Introduction: To demonstrate the physiological mechanical forces on the medial and lateral femoral cortices in Total Hip Replacement (THR), the cementless “lateral flare” femoral stem has been developed, established, and clinically validated at our institution. The mid-term outcomes had been reported, and therefore, the long-term outcomes of this femoral stem were evaluated in this study.
Patients and methods: A total of 62 hips in 58 consecutive patients, which had been previously reported, were investigated by physical examinations, radiographic evaluations and telephone interviews.
Results: There were 49 hips in 45 patients (79.0%) available for long-term follow-up. of the 49 hips; the mean duration of follow-up period was 15.8 ± 1.5 years (10.1-17.9 years). There were no cases of critical stress shielding which required revision surgery of any femoral components. Consequently, no femoral components have been revised at the time of this report.
Discussion: Besides the lateral expansion, this femoral stem has a trapezoidal shape of the cross section in the proximal one-third, and a flat posterior surface with a fixed anteversion in the neck. Because of these features, this stem could demonstrate the physiological forces on femur and the stabilization against rotation forces encountered inside the femoral canal.
Conclusion: The lateral flare stem is a promising prosthesis with a carefully considered design, which provides not only initial stability but long-term stability and bone preservation throughout a long follow-up period.