Is It Time to Rethink the Relationship Between Subscapularis Tears and the Long Head of Biceps Tendon?

Introduction Pre-operative diagnosis of subscapularis tears remains a difficult challenge. Ultrasound has been shown to be ineffective at directly detecting subscapularis tears. It has been widely accepted that medial subluxation of the long head of biceps tendon (LHBT) is associated with full-thickness subscapularis tears. The aims of this study are to assess whether LHBT subluxation on ultrasound scanning has any predictive value for subscapularis tears and to determine the relationship between LHBT subluxation and subscapularis tears at arthroscopy. Methods Pre-operative ultrasound and arthroscopic findings for patients undergoing arthroscopic rotator cuff repair at our institution between March 2011 and January 2016 were analysed. The accuracy of LHBT subluxation on ultrasound and at arthroscopy as a predictor of subscapularis tears at arthroscopy was calculated. The correlation between LHBT subluxation and subscapularis tears was determined. A standardised technique was used for ultrasound scans, and the grade of the sonographer was recorded. Results Three hundred fifty-nine rotator cuff repairs were performed. Twenty-four patients had a subluxed LHBT. Ultrasound was poorly sensitive (50%), and a subluxed LHBT on ultrasound only correlated very weakly with subscapularis tears at arthroscopy (R = 0.268, p<0.001). At arthroscopy, 92 patients had full-thickness subscapularis tears. Of these, only 16 patients (17%) had a subluxed/dislocated LHBT. Of the 24 patients with a subluxed LHBT, eight had no subscapularis tears. Thus, LHBT subluxation/dislocation only correlated weakly with full-thickness subscapularis tears (R=0.252, p<0.001). Conclusion Due to their close anatomical relationship, traditional teaching suggests subscapularis tears are associated with medial LHBT subluxation. Our data indicate that, contrary to popular belief, the two are only weakly correlated. In our series, the majority of patients with subscapularis tears (83%) had their LHBT in-groove. The authors therefore recommend high vigilance during arthroscopy for the diagnosis and repair of subscapularis tears, regardless of pre-operative ultrasound findings and the intra-operative position of the LHBT.

Thresholds for indirect DNA damage across cellular barriers for orthopaedic biomaterials.

Cobalt-chromium particles and ions can induce indirect DNA damage and chromosome aberrations in human cells on the other side of a cellular barrier in tissue culture. This occurs by intercellular signalling across the barrier. We now show that the threshold for this effect depends on the metal form and the particle composition. Ionic cobalt and chromium induced single strand breaks at concentrations equivalent to those found in the blood of patients with well functioning metal on metal hip prostheses. However, they only caused double strand breaks if the chromium was present as chromium (VI), and did not induce chromosome aberrations. Nanoparticles of cobalt-chromium alloy caused DNA double strand breaks and chromosome aberrations, of which the majority were tetraploidy. Ceramic nanoparticles induced only single strand breaks and/or alkaline labile sites when indirectly exposed to human fibroblasts. The assessment of reproductive risk from maternal exposure to biomaterials is not yet possible with epidemiology. Whilst the barrier model used here differs from the in vivo situation in several respects, it may be useful as a framework to evaluate biomaterial induced damage across physiological barriers.

Nanoparticles can cause DNA damage across a cellular barrier.

The increasing use of nanoparticles in medicine has raised concerns over their ability to gain access to privileged sites in the body. Here, we show that cobalt-chromium nanoparticles (29.5 +/- 6.3 nm in diameter) can damage human fibroblast cells across an intact cellular barrier without having to cross the barrier. The damage is mediated by a novel mechanism involving transmission of purine nucleotides (such as ATP) and intercellular signalling within the barrier through connexin gap junctions or hemichannels and pannexin channels. The outcome, which includes DNA damage without significant cell death, is different from that observed in cells subjected to direct exposure to nanoparticles. Our results suggest the importance of indirect effects when evaluating the safety of nanoparticles. The potential damage to tissues located behind cellular barriers needs to be considered when using nanoparticles for targeting diseased states.

An experimental comparison of handover methods.

INTRODUCTION: With the increase in shift pattern work for junior doctors in the NHS, accurate handover of patient clinical information is of great importance. There is no published method that forms the gold standard of handover and there are large variations in practice. This study aims to compare the reliability of three different handover methods. PATIENTS AND METHODS: We observed the handover of 12 simulated patients over five consecutive handover cycles between SHOs on a one-to-one basis. Three handover styles were used and a numerical scoring system assessed clinical information lost per handover cycle. RESULTS: After five handover cycles, only 2.5% of patient information was retained using the verbal-only handover method, 85.5% was retained when using the using the verbal with note taking method and 99% was retained when a printed handout containing all patient information was used. CONCLUSIONS: When patient information is handed over by the verbal only method, very few facts are retained; therefore, this method should be avoided whenever possible. Verbal handover with note taking is shown to be an effective method of handover in our study, although we accept that this is an artificial scenario and may not reflect the reality of a busy hospital. Nearly all information is retained by the printed handout method but this relies on the handout being regularly updated.