Shoulder & Elbow

Propionibacterium acnes in primary shoulder arthroplasty: is it a technical surgical issue?

In the last edition of 360, we discussed a paper evaluating the role of single-stage revision shoulder arthroplasty in patients with subclinical infection, where almost half of all revised cases had more than two positive cultures for Propionibacterium acnes (P. acnes).³P. acnes is known to be associated with indolent infection leading to osteolysis and loosening of shoulder prostheses, and is of great concern to shoulder surgeons. In this thought-provoking study from Australia, microbiological samples were obtained from a range of potential contaminant sites in 40 consecutive patients undergoing primary shoulder arthroplasty. These authors from St Leonards (Australia)⁴ designed a study where cultures via swab were obtained from consecutive patients undergoing primary shoulder arthroplasty. In each patient, specimens were taken from the subdermal layer, the tip of the surgeon’s glove, the deep scalpel blade, forceps and the skin incision scalpel blade. The study is based on the results of 40 patients, all undergoing shoulder arthroplasty. Of these, one third had at least a single culture positive for P. acnes, with 8% of females (n = 2/25) and 73% of males (n = 11/15) having more than a single positive culture. The most common site of contamination was the subdermal tissue (12 positive samples), however, there was a worrying rate of contamination of surgical gloves (seven samples) and forceps (seven samples). Allowing for the difficulties that culture of P. acnes poses in the laboratory, it is certainly possible that there were still more positive samples. The authors determined that males had a 66-fold increased chance of having a positive microbiological culture for subdermal colonisation and not unreasonably concluded that P. acnes can be found throughout the surgical field. This seemingly ever-present microbe is a persistent problem to shoulder surgeons and, as the team from Australia have suggested, given the high rate of surgeon contamination presented here new approaches are certainly needed to try to reduce the risk of colonisation at the time of primary surgery.

Primary elbow arthroplasty in distal humeral fractures

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The use of primary total elbow replacement (TER) for distal humeral fractures is on the rise but the reasons for this are unclear. Is this trend due to improved surgical results or a change in the pattern of presentation of these fractures? As the number of elderly complex osteoporotic distal humeral fractures grows, there is an increasing interest in the role of TER for these injuries. In 2009, McKee and the COTS group provided the best evidence (although flawed) to date with their multicentre prospective randomised controlled trial of ORIF versus TER for distal humeral fractures in the elderly. The results of this trial were in favour of TER, with more predictable and superior functional outcomes for TER when compared with ORIF.⁵ In this registry study from Los Angeles, California (USA) utilising the Nationwide Inpatient Sample database, the authors sought to establish what were the trends in the use of TER for distal humeral fractures in elderly patients (⩾ 65 years of age).⁶ The study analysed data over a ten-year period from 2002 to 2012. The take-home message from this registry-based study is that there was a 2.6-fold annual increase in the use of TER for these injuries. Surgery accounted for 13% of surgically managed distal humeral fractures in 2012, a significant increase from the baseline value of 5.1% seen in 2002. In terms of overall costs, TER was over $16,000 more expensive than ORIF. Interestingly, the authors comment that, given the ‘complexity, long-term restrictions and risks associated with TER’, this increasing trend needs to be monitored closely. Here at 360, we would echo the conclusion of the COTS group’s study that arthroplasty is really only a preferred treatment method in these elderly patients when the complexity of the fracture means that stable fixation is not attainable. The rise in the use of TER highlighted in this study seems likely to be related to the rise in the number of osteoporotic distal humeral fractures, meaning that TER needs to be utilised on an increasing basis. However, most would agree that the indications and long-term outcome of TER for trauma are still to be fully defined, especially for an intervention reported to cost in excess of $85,000.