The primary stability of the hip transposition type IIb: A biomechanical in vitro study

Wessling, Martin; Aach, Mirko; Herbort, Mirko; Gosheger, Georg; Hardes, Jendrik; Gebert, Carsten

doi:10.1016/j.clinbiomech.2009.01.008

« Previous Next »Clinical Biomechanics
Volume 24, Issue 4 , Pages 361-365, May 2009

The primary stability of the hip transposition type IIb: A biomechanical in vitro study

Martin Wessling
- Department of Orthopaedic Surgery, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48149 Muenster, Germany
- Department of Tumour and Revision Surgery, Orthopaedic Hospital Volmarstein, Lothar-Gau-Str. 11, D-58300 Wetter, Germany
- Corresponding author. Address: Department of Orthopaedic Surgery, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48149 Muenster, Germany.
- Martin Wessling and Mirko Aach contributed equally for this paper.
Mirko Aach
- Department of Spinal Chord Injuries, University Hospital Bergmannsheil Bochum, Bürkle-de-la-Camp-Platz 1, D-44789 Bochum, Germany
- Martin Wessling and Mirko Aach contributed equally for this paper.
Mirko Herbort
- Department of Trauma, Hand and Reconstructive Surgery, University Hospital Muenster, Waldeyerstraße 1, D-48149 Muenster, Germany
Georg Gosheger
- Department of Orthopaedic Surgery, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48149 Muenster, Germany
Jendrik Hardes
- Department of Orthopaedic Surgery, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48149 Muenster, Germany
Carsten Gebert
- Department of Orthopaedic Surgery, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48149 Muenster, Germany
- Department of Tumour and Revision Surgery, Orthopaedic Hospital Volmarstein, Lothar-Gau-Str. 11, D-58300 Wetter, Germany

Received 7 December 2008; accepted 21 January 2009. published online 26 February 2009.

Abstract

Background

The hip transposition is firmly established in pelvic sarcoma surgery. However, the primary stability of the hip transposition has not been tested yet so that the mobilisation, respectively the immobilisation of the patient so far solely relied on the experience of the surgeon. The aim of this study was to test the primary stability reliably with the help of a model and to reveal possible differences in stability between currently used anchor systems (TwinFix^® 6.5 and MITEK^® SuperAnchor^®).

Methods

A biomechanical model of porcine sacra was developed to document the maximum load capacity (load to failure test) and the performance under cyclic load (100N, 200N, 350N, 700N, 1400N, each with 1000 cycles), 28 sacra were tested in total. Macroscopic damages, displacement, yield load, stiffness and F_max were recorded as well.

Findings

The load to failure test results showed a 3,9 times higher maximum load capacity for the TwinFix^® 6.5 anchor (1307N) compared to the MITEK^® SuperAnchor^® (334N). The cyclical test revealed that nearly all MITEK^® SuperAnchors^® failed at a load of 350N. In contrast, the TwinFix^® 6.5 anchors resisted 4000 cycles up to a load of 1400N.

Interpretation

The TwinFix^® 6.5 anchor proved to be clearly superior to the MITEK^® SuperAnchor^®, resulting in the adjustment of the reconstruction technique. Therefore, the immobilisation period of a patient after a hip transposition type IIb could be shortened according to the results of the primary stability test.

Keywords: Pelvic tumour, Hip transposition, Primary stability, Biomechanical study