TRIPLE TAPERED C-STEM TOTAL HIP ARTHROPLASTY: EARLY RESULTS FROM A SINGLE SURGEON SERIES OF 290 (260 PATIENTS) TOTAL HIP REPLACEMENTS AT A MINIMUM OF 3 YEARS FOLLOW UP IN A DISTRICT GENERAL HOSPITAL.

Abstract

Introduction: The C-Stem was introduced in the endeavour to achieve greater stability, improved fixation, minimise subsidence and improve loading of the proximal femur to maintain bone quality and avoid stress shielding. Since promising early results in 2001, no studies including a large patient population from a single surgeon series have been published.

Methods: Health records and imaging modalities of 260 patients, operated between 2001 and 2004 were retrospectively evaluated by 2 independent reviewers. All patients had antero-lateral approach in supine position. Clearing of the calcar was carried out to allow adequate cement mantle proximally and posteromedially. Tip of the stem was allowed to penetrate in to the intramedullary bone block. All patients were followed up regularly with clinical and radiological information being updated.

Results: 90 men and 170 women, 30 bilateral cases were identified. Mean age at the time of surgery was 61.8 years (50–91). Commonest diagnosis was primary OA (56%) followed by secondary OA due to AVN or childhood pathology (30%) and previous trauma. 43 patients had previous operations in the form of failed internal fixation, osteotomy or hemiarthroplasty. Assessment included oxford hip score. Radiographs digitalised on DICOM software were analysed for subsidence (0.7 mm), alignment (94% satisfactory), bone-cement interface changes (35% progressive improvement) and proximal femur stress shielding (2.1%). At the time of final follow up 89% were independently mobile. 4 % thigh pain, 3 revisions for recurrent dislocations, 3 nonfatal and 2 fatal pulmonary embolism. Taking death or revision for any reason as endpoints, 97.8% survivorship was noted using Kaplan-miere analysis.

Discussion: The strength of the study includes large patient population, completeness of follow up and single surgeon series eliminating compounding factors. Bone cement interface improvement was noted in younger patients with high activity level. The study consolidates the soundness of the concept of C-Stem.