Use of a threaded-coupled femoral extraction device allows for higher extraction force when compared to loop or vice grip devices; A potted stem analysis.

BACKGROUND

Extraction of a well-fixed femoral stem during revision total hip arthroplasty presents a technical challenge to the operating surgeon. The option of several stem designs during implantation necessitates the availability of extraction tools to be utilised intra-operatively. This study aims to compare the amount of axial force generated from using a threaded-coupled extraction device, loop extraction device, and vice-grip universal extraction set on a potted total hip arthroplasty stem construct.

METHODS

A size 7 Stryker Accolade® II femoral stem (Stryker, Mahwah, NJ) was potted within a 5.20 cm inner diameter polyvinyl chloride pipe using a potting medium with tensile strength and lap shear of 1000psi. This construct was coupled to a material testing system whose force transducer was calibrated to a recording speed of 1000 frames per second. The extractors were coupled to the potted stem, and a force of 1.32 J was applied ten times sequentially to each construct. Force was recorded in Newtons.

RESULTS

The maximum average force for the threaded, loop, and Shukla extractors was 111.46 ± 1.77 N, 90.22 ± 0.87 N, and 64.70 ± 9.03 N (p < 0.01). Loss of coupling was not experienced with any extractor.

CONCLUSION

Within our study, the forces observed per constant load when utilising a threaded-coupled extraction device that attaches to the shoulder of the implant were significantly higher than those seen when using an extraction device that couples to the neck of the femoral stem.