Abstract
Introduction
Although total hip replacement (THR) has been described as the operation of the century, there is still room for improvement. There is therefore continued effort for advanced implants and bearing surfaces, moreover so, for the younger patient with a longer life expectancy and increased needs.
Objectives
This prospective case-series study aims to present the preliminary, minimum three-years, results of a novel uncemeted stem, the Leader StemÒ (Vadin Implants Ltd, London, U.K.). The Leader StemÒ is a titanium, tapered stem for immediate three-point fixation. There is a metaphyseal porous-coating with titanium microspheres for bone in-growth. It has anti-rotational ribs in the metaphyseal - diaphyseal junction to promote initial stability and a grit blasted diaphyseal region for bone on-growth. The distal tip is polished and shortened to minimize thigh pain, while the whole design and concept is one to eradicate stress shielding.
Methods
Between June 2010 and May 2012 we operated on 20 males and 29 female patients (53 THRs, mean age 66±13 years). The diagnosis was osteoarthritis in 39 patients (41 THRs), developmental dysplasia in six patients (eight THRs), avascular necrosis in two patients (two THRs) and chondrolysis in two patients (two THRs). Operations were performed by the posterior approach by two hip surgeons. The bearing surface was ceramic on ceramic in six patients (eight THRs), metal on polyethylene in 22 patients (22 THRs) and ceramic on polyethylene in 21 patients (23 THRs). Patients' demographic data, Harris Hip Scores (HHS) and Oxford Hip Scores (OHS) were collected prospectively, preoperatively, postoperatively, and at six months intervals thereafter. Radiographic evaluation was performed on standard anteroposterior and lateral X-rays at the same time intervals.
Results
At last follow-up, mean 50 months after surgery, no revision for any reason has been reported. Six patients were lost to follow-up and one deceased three years post-operatively from an unrelated reason with a stable and untroubled prosthesis. There was one periprosthetic fracture two years after the initial operation but with a stable prosthesis, which was treated with open reduction – internal fixation. Three patients had complained of thigh pain, which had resolved at last follow up. At the most recent follow-up, the average HHS improved from 33.9±13.6 preoperatively to 89.35±12.72 and OHS from 12.7±5.6 to 41.6±7.2. No clinical score was significantly correlated to any demographic index, but the latest HHS was well correlated to the pre-operative score (R=0.41, p=0.007). Radiographically, no radiolucent lines in any of the Gruen zones and no stem subsidence were observed at any time interval, while cortical hypertrophy was observed at the diaphyseal zone in two patients.
Conclusions
This study showed that this new press-fit stem design had excellent short-term clinical and radiological results in all followed-up patients, irrespective of their age, gender, and body mass index. Longer follow-up is needed to evaluate its long-term survival and effectiveness.
