Open Access Study protocol

Minimally invasive computer-navigated total hip arthroplasty, following the concept of femur first and combined anteversion: design of a blinded randomized controlled trial

Tobias Renkawitz1*, Martin Haimerl2, Lars Dohmen2, Sabine Gneiting2, Melanie Wegner2, Nicole Ehret2, Claudia Buchele2, Mario Schubert2, Philipp Lechler1, Michael Woerner1, Ernst Sendtner1, Tibor Schuster3, Kurt Ulm3, Robert Springorum1 and Joachim Grifka1

Author Affiliations

1 Department of Orthopaedic Surgery, Regensburg University Medical Center, Germany

2 Brainlab AG, R&D Surgery, Feldkirchen, Germany

3 Institute for Medical Statistics and Epidemiology, TU Muenchen, Germany

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BMC Musculoskeletal Disorders 2011, 12:192  doi:10.1186/1471-2474-12-192

Published: 19 August 2011

Abstract

Background

Impingement can be a serious complication after total hip arthroplasty (THA), and is one of the major causes of postoperative pain, dislocation, aseptic loosening, and implant breakage. Minimally invasive THA and computer-navigated surgery were introduced several years ago. We have developed a novel, computer-assisted operation method for THA following the concept of "femur first"/"combined anteversion", which incorporates various aspects of performing a functional optimization of the cup position, and comprehensively addresses range of motion (ROM) as well as cup containment and alignment parameters. Hence, the purpose of this study is to assess whether the artificial joint's ROM can be improved by this computer-assisted operation method. Second, the clinical and radiological outcome will be evaluated.

Methods/Design

A registered patient- and observer-blinded randomized controlled trial will be conducted. Patients between the ages of 50 and 75 admitted for primary unilateral THA will be included. Patients will be randomly allocated to either receive minimally invasive computer-navigated "femur first" THA or the conventional minimally invasive THA procedure. Self-reported functional status and health-related quality of life (questionnaires) will be assessed both preoperatively and postoperatively. Perioperative complications will be registered. Radiographic evaluation will take place up to 6 weeks postoperatively with a computed tomography (CT) scan. Component position will be evaluated by an independent external institute on a 3D reconstruction of the femur/pelvis using image-processing software. Postoperative ROM will be calculated by an algorithm which automatically determines bony and prosthetic impingements.

Discussion

In the past, computer navigation has improved the accuracy of component positioning. So far, there are only few objective data quantifying the risks and benefits of computer navigated THA. Therefore, this study has been designed to compare minimally invasive computer-navigated "femur first" THA with a conventional technique for minimally invasive THA. The results of this trial will be presented as soon as they become available.

Trial registration number

DRKS00000739