Incomplete seating of the liner with the Trident acetabular system: a cause for concern?

We reviewed the initial post-operative radiographs of the Trident acetabulum and identified a problem with seating of the metal-backed ceramic liner. We identified 117 hips in 113 patients who had undergone primary total hip replacement using the Trident shell with a metal-backed alumina liner. Of these, 19 (16.4%) were noted to have incomplete seating of the liner, as judged by plain anteroposterior and lateral radiographs. One case of complete liner dissociation necessitating early revision was not included in the prevalence figures. One mis-seated liner was revised in the early post-operative period and two that were initially incompletely seated were found on follow-up radiographs to have become correctly seated. There may be technical issues with regard to the implanting of this prosthesis of which surgeons should be aware. However, there is the distinct possibility that the Trident shell deforms upon implantation, thereby preventing complete seating of the liner.

The role of laser Doppler flowmetry in assessing the viability of bone fragments in an open fracture.

The management of open fractures requires excision of all devitalised tissues, both bony and soft tissue, and failure to do so is likely to increase the risk of infection. This study evaluated the applicability of laser Doppler flowmetry for the objective evaluation of fracture fragment viability in an experimental open ballistic fracture over a period of 12 h. The results indicate that this technique could not be used to distinguish between vascularised and non-vascularised fragments at any time, and did not aid the surgeon in their decision making at the time of wound excision. Subjective evaluation, based upon the degree of soft tissue attachment of fragments, was a far better indicator of fragment vascularity, although it had a relatively low specificity. There remains the need for education and training for trauma surgeons in the evaluation of fragment viability to ensure adequate wound excision as part of fracture management.

Anal gland carcinoma.

BACKGROUND: Anal gland carcinoma is a rare entity. The authors conducted a joint study of cases coded as definite or possible anal gland carcinoma from the archives of the Armed Forces Institute of Pathology and the Canadian Reference Center for Cancer Pathology. METHODS: Seven cases of potential anal gland carcinoma were identified from the Canadian files and 12 from the Armed Forces Institute of Pathology archives. Of these 19 cases, 14 had adequate material to allow clinical, histologic, and immunohistochemical analysis. RESULTS: Seven of these 14 cases met a modified World Health Organization (WHO) definition of anal gland carcinoma. The mean age of these patients was 66 years (range, 60-72 years), with a male-to-female ratio of 6:1. The tumors were composed of haphazardly dispersed, small glands with scant mucin production that invaded the wall of the anorectal area with no obvious intraluminal component observed clinically or microscopically. Immunohistochemical studies were performed on all seven of these cases, revealing cytokeratin (CK) 7+/CK 20- expression in six cases, and CK 7+/CK 20+ expression in one case. The remaining seven cases showed no intraluminal component but did not meet a modified WHO definition of anal gland carcinoma. This group included three mucinous adenocarcinomas (two clinically arising in anal fistulas), all of which were CK 7+/CK 20+, and a rectal-type adenocarcinoma that was CK 7-/CK 20+. There was also a tumor interpreted as probable rectal-type adenocarcinoma that was CK 7+/CK 20+, and a tumor interpreted as probable squamous cell carcinoma that was CK 7-/CK 20-. The seventh tumor in this group, which could not be classified, was CK 7+/CK 20-. CONCLUSIONS: A useful and discriminating definition of anal gland carcinoma is an anal canal tumor composed of haphazardly dispersed, small glands with scant mucin production invading the wall of the anorectal area without an intraluminal component. The glands are positive for CK 7.

Evaluation of the viability of bone fragments.

We used laser Doppler flowmetry (LDF) to measure flux in cortical bone fragments as a method of determining their vascular status and viability. In an experimental tibial osteotomy measurements of flux were made from specific cortical sites both before and after osteotomy. Flux levels fell rapidly in non-vascularised fragments and remained significantly reduced throughout the experiment. By contrast, those in vascularised fragments were significantly reduced one and two hours after the osteotomy but then increased. From three hours after the osteotomy there was no significant difference in flux levels between the vascularised fragments and proximal bone stock. We conclude that measurement of bone flux by LDF may have a role in the objective evaluation of the viability of bone fragments, but that further studies are required to validate the technique before its adoption in the management of the injured patient.