Research

Wasted implants

x-ref Hip, Knee, Shoulder

In a brief report from Akron (USA), the management of a surgeon-owned hospital tried a novel method for reducing wasted implants. The study team identified that a 1.5% implant wastage rate was occurring in their institution during arthroplasty surgery. The (arguably slightly aggressive) response was the publication of an open ‘league table’ of surgeons’ implant wastage rates. Roll on one year, and the authors repeated their audit with, it appears, little effect. A statistically insignificant improvement in implant wastage to 1.1% was seen.¹ It does beg the question as to whether, with apparent ‘mistake’ rates of over 1% in implant selection in theatre, the labelling is good enough on implant boxes. Surely with the public naming and shaming approach taken by these authors, surgeons will have done their utmost to reduce implant wastage?

Biofilms revisited

x-ref Hip, Knee, Shoulder, Ankle, Trauma

One explanation for the difficulties facing revision surgeons in eradiating infection is the persistence of biofilms. Bacteria arranged in a semi-dormant state under a protective layer of glycocalyx on the surface of an implant are often surprisingly resistant to antibiotics, lavage and even aggressive debridement. A pair of papers shed some light on potential, more direct physical attacks during revision surgery to address this problem. Researchers in Surrey (UK)² (and we admit, here at 360, that we are likening the biofilm effect to that seen commonly in dental plaque) have used an experimental model to test the value of sodium bicarbonate (thought in dentistry to be effective) on disrupting biofilms. Their model consisted of some fermenter-grown human dental biofilms. Each was subjected to a different concentration of sodium bicarbonate and the efficacy assessed using colony viability counts on microscopy. In short, these investigative dentists established that sodium bicarbonate is most effective in older, more established biofilm models.In a similarly experimental paper, researchers in Copenhagen (Denmark) evaluated the potential for acetic acid (vinegar) to effectively disrupt biofilm-established bacteria. These authors present a comprehensive look at the potential for acetic acid to be used as an anti-biofilm agent. Their rather general article covers both gram-positive and gram-negative bacteria, along with some anecdotal clinical evidence.³ While we are not supposing for a minute that either of these two articles holds the key to dealing with infected biofilm-colonised joints, it is clear that new and inventive approaches are required, and examining the mechanism of action of topical non-toxic agents may yield some novel treatments in the future.

Peri-operative anticoagulation not required in atrial fibrillation

x-ref Hip, Knee, Foot, Hand, Shoulder, Spine, Trauma, Oncology, Paeds, Research

In a game-changing paper for peri-operative management, researchers in Copenhagen (Denmark) have debunked another myth surrounding low molecular weight heparins (LMWH). Common practice the world over has been to place patients on warfarin on a ‘bridging’ anticoagulation with LMWH. This has been for two reasons: to protect them in the peri-operative period, and also to cover the re-warfarinisation period which is associated with a transient hypercoagulant state as warfarin preferentially inhibits anti-protein C and anti-protein S over other clotting factors. The need to provide bridging cover in patients with a strong history of thrombosis (e.g. major PE, proximal DVT or arterial embolus) seems sensible, but what about the relative indications such as providing cover for patients on warfarin for atrial fibrillation (AF)? The research team conducted an impressive randomised controlled trial involving 1884 patients, half randomised to LMWH cover for the peri-operative period and the other half randomised to placebo. Outcomes were assessed within 30 days of the procedure and primarily thromboembolic events (stroke, SVTE, TIA) were taken as end points. The incidence of adverse thromboembolic events was 0.3% in the bridging group and 0.4% in the non-bridging group. With a study like this powered for non-inferiority, this result suggests that the use of bridging anti-coagulation was not required in patients with AF and on warfarin.⁴ Although many clinicians do not use VTE prophylaxis in this group, this is nevertheless a landmark paper demonstrating once and for all that it is an unnecessary health economic burden, not to mention the inconvenience caused to patients and clinicians.

Determinants in outcome following orthopaedic surgery

x-ref Hip, Knee, Foot, Hand, Shoulder, Spine, Trauma, Oncology, Paeds, Research

Orthopaedic surgeons, especially arthroplasty surgeons, are being monitored extensively on their outcomes. Publicly available data in many healthcare economies now not only list ‘hard’ end points like death, infection and revision surgery (which we all know have a significant element of selection and practice bias) by hospital, but also by surgeon. It will not be long before patient-reported outcome measures (PROMS) are publically available. One of the dangers of this kind of data transparency is that outcome measures may not always be reporting what we believe them to be. The more generalisable, self-administered and subjective a measure (such as the EQ5D, DASH, etc), the less it is potentially subject to administrator bias, but the more it is subject to patient bias. Consciously or not, the majority of these scores likely also measure patient experience. Researchers in Durham (USA) have set out to quantify the effect of some ‘non-modifiable’ risk factors on patient satisfaction scores. The research team used a previously collected large sample of 12 177 outpatient clinical encounters at a teaching hospital in an effort to partly unpick what is to a certain extent a Gordian knot. The study team used this sample of pre-collected data and divided the patients into ‘generally satisfied’ and ‘unsatisfied’ subgroups. A number of potential non-modifiable confounders were also evaluated including age, sex, employment, health insurance, zip code and subspecialty. Although a more complex multivariant analysis model may have been more appropriate, the authors used a perfectly acceptable statistical model looking for predictors of satisfaction and dissatisfaction. Their analysis suggested that increasing age was strongly associated with satisfaction (younger patients being less satisfied) and patients who have travelled further, curiously, were more satisfied with their care.⁵ The authors of this interesting study make a good point, and one that will not be news to any practising orthopaedic surgeon. Patient-reported outcomes are as much about the patient and the environment as they are about the surgery. This of course doesn’t make them an invalid outcome tool – assuming, that is, that everyone has the same patient mix.

Patient ‘activation’ and outcomes

Patient ‘activation’ is a bit of a buzz word on the other side of the pond, but we are sure it is a concept with which we are going to become familiar the world over. There are patients who do well and patients who do not – this is a truism in all types of medicine and surgery. The more experienced clinician will always talk about ‘picking a winner’, but how do we know or quantify who are going to be winners. Patient activation goes some way towards explaining this. It is the concept that a patient’s ability to engage with adaptive health behaviours might be as important in achieving a good result as many other factors. In one of the first papers studying the effects of activation, researchers in Salt Lake City (USA) have explored the relationship between patient activation and joint arthroplasty outcome scores. The study is a simply designed, prospective case series of 134 patients undergoing hip or knee arthroplasty at one of two centres. Data were collected pre-operatively including the patient activation measure (PAM), Hip Disability and Osteoarthritis Outcome Score (HDOS) and Knee Injury and Osteoarthritis Outcome Score (KOOS). Patients’ activity and quality of life measures were quantified using the UCLA and SF-12 scores.⁶ The results themselves are both intuitive and fascinating. Patients with higher PAM scores experienced improved outcomes as measured by the KOOS and HDOS scores. Perhaps unsurprisingly, a higher PAM score was also associated with improvement in post-operative satisfaction and physical health scores.

Neuroplasticity and nerve repair

x-ref Hand; Shoulder

In one of the most interesting papers to cross the 360 editors’ desk in some time, researchers in Malmö (Sweden) ask this fascinating question in their small-scale randomised controlled trial: can neuroplasticity improve outcomes in nerve repair? Their study concerns the outcomes of 39 patients, all with median or ulnar nerve injuries who underwent primary repairs in the forearm. Participants were randomised to start sensory and motor relearning either within a week of the injury - well before any regeneration - or only once there were clinical signs of regeneration.⁷ The sensory outcomes in the early intervention group were significantly better (as measured by the texture and shape discrimination domains of the Rosen score), with improved shape discrimination. Although a small-scale study, this should be a game changer in the field of peripheral nerve repair. There are few drawbacks to starting rehabilitation early and clearly encouraging early plasticity pays dividends later.

KOOS score in predicting injury?

x-ref Knee

It has been known for some time that there are significant gender differences in both the propensity to injure the knee and the injury patterns that occur. There is some suggestion that self-reporting of previous knee injury and lower Knee Injury and Osteoarthritis Outcome Scores (KOOS) may have a predictive value in anticipating future injuries in other areas of sports. However, curiously there have been no studies to date in female footballers, one of the highest risk groups for knee injuries.⁸ A research team in Amager-Hvidovre (Denmark) undertook a simple epidemiology study of 326 adolescent female football players without injury, as a baseline cohort. They recorded the players’ self-reported previous knee injuries and administered a KOOS score. Rather innovatively, the research team utilised text message technology to undertake weekly surveys of participants’ time lost from play. Risk factor analysis was undertaken and established that previous self-reported knee injuries (relative risk 3.65) and all KOOS subscores were also predictive of future time lost from play due to injury when less than 80 points. Female soft-tissue knee injuries are one of the areas where ‘prehab’ with appropriate proprioceptive and muscle-strengthening exercise has been demonstrated to reduce the rate of future injury. Perhaps targeting this intervention at young female players with these risk factors could reduce injury rates even further.