The influence of contamination and cleaning on the strength of modular head taper fixation in total hip arthroplasty

• Published in: The Journal of arthroplasty 2017-10, Vol.32 (10), p.3200-3205
• Main Authors: Krull, Annika, M.Sc, Morlock, Michael M., Univ. Prof., Dr.habil., Ph.D, Bishop, Nicholas E., Prof. Dr.-Ing
• Format: Article
• Language: English
• Subjects: Alloys; Animals; Arthroplasty, Replacement, Hip - standards; Cattle; Ceramics; contamination; Corrosion; Equipment Contamination; fat; Fats - adverse effects; Hip Prosthesis - standards; Humans; impaction; Mechanical Phenomena; Orthopedics; Prosthesis Failure; Prosthesis Retention; pull-off force; Sodium Chloride - adverse effects; taper connection; Titanium; total hip arthroplasty (THA)
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1016/j.arth.2017.05.009

Background Intraoperative interface contamination of modular head-stem taper junctions in total hip replacement can lead to poor fixation strength, which can cause fretting and crevice corrosion or even stem taper fracture during loading. Careful cleaning prior to assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. Methods Metal- or ceramic heads were impacted onto titanium alloy stem tapers with their interfaces either clean or contaminated with fat or saline solution. The same procedure was performed after cleaning the contaminated interfaces using saline solution and dry gauze dressings, resulting in a total of 10 groups (n=5). Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. Results Pull-off forces after contamination with fat were significantly lower than for the uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution without drying were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, with forces in some cases so low that manual removal of the head was possible. Cleaned and dried tapers achieved similar pull-off forces as the uncontaminated tapers for both head materials. Conclusion Intra-operative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly prior to assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength.