Bdellovibrio bacteriovorus uses chimeric fibre proteins to recognize and invade a broad range of bacterial hosts.

Predatory bacteria, like the model endoperiplasmic bacterium Bdellovibrio bacteriovorus, show several adaptations relevant to their requirements for locating, entering and killing other bacteria. The mechanisms underlying prey recognition and handling remain obscure. Here we use complementary genetic, microscopic and structural methods to address this deficit. During invasion, the B. bacteriovorus protein CpoB concentrates into a vesicular compartment that is deposited into the prey periplasm. Proteomic and structural analyses of vesicle contents reveal several fibre-like proteins, which we name the mosaic adhesive trimer (MAT) superfamily, and show localization on the predator surface before prey encounter. These dynamic proteins indicate a variety of binding capabilities, and we confirm that one MAT member shows specificity for surface glycans from a particular prey. Our study shows that the B. bacteriovorus MAT protein repertoire enables a broad means for the recognition and handling of diverse prey epitopes encountered during bacterial predation and invasion.

How to prioritize patients and redesign care to safely resume planned surgery during the COVID-19 pandemic.

AIMS: Restarting planned surgery during the COVID-19 pandemic is a clinical and societal priority, but it is unknown whether it can be done safely and include high-risk or complex cases. We developed a Surgical Prioritization and Allocation Guide (SPAG). Here, we validate its effectiveness and safety in COVID-free sites. METHODS: A multidisciplinary surgical prioritization committee developed the SPAG, incorporating procedural urgency, shared decision-making, patient safety, and biopsychosocial factors; and applied it to 1,142 adult patients awaiting orthopaedic surgery. Patients were stratified into four priority groups and underwent surgery at three COVID-free sites, including one with access to a high dependency unit (HDU) or intensive care unit (ICU) and specialist resources. Safety was assessed by the number of patients requiring inpatient postoperative HDU/ICU admission, contracting COVID-19 within 14 days postoperatively, and mortality within 30 days postoperatively. RESULTS: A total of 1,142 patients were included, 47 declined surgery, and 110 were deemed high-risk or requiring specialist resources. In the ten-week study period, 28 high-risk patients underwent surgery, during which 68% (13/19) of Priority 2 (P2, surgery within one month) patients underwent surgery, and 15% (3/20) of P3 (< three months) and 16% (11/71) of P4 (> three months) groups. Of the 1,032 low-risk patients, 322 patients underwent surgery. Overall, 21 P3 and P4 patients were expedited to 'Urgent' based on biopsychosocial factors identified by the SPAG. During the study period, 91% (19/21) of the Urgent group, 52% (49/95) of P2, 36% (70/196) of P3, and 26% (184/720) of P4 underwent surgery. No patients died or were admitted to HDU/ICU, or contracted COVID-19. CONCLUSION: Our widely generalizable model enabled the restart of planned surgery during the COVID-19 pandemic, without compromising patient safety or excluding high-risk or complex cases. Patients classified as Urgent or P2 were most likely to undergo surgery, including those deemed high-risk. This model, which includes assessment of biopsychosocial factors alongside disease severity, can assist in equitably prioritizing the substantial list of patients now awaiting planned orthopaedic surgery worldwide. Cite this article: Bone Jt Open 2021;2(2):134-140.

Benefits of rapid deployment aortic valve replacement with a mini upper sternotomy.

BACKGROUND: Surgical aortic valve replacement (AVR) is currently deemed the gold standard of care for patients with severe aortic stenosis. Currently, most AVRs are safely performed through a full median sternotomy approach. With an increasingly elderly and high-risk patient population, major advances in valve technology and surgical technique have been introduced to reduce perioperative risk and post-operative complications associated with the full sternotomy approach, in order to ensure surgical AVR remains the gold standard. For example, minimally invasive approaches (most commonly via mini sternotomy) have been developed to improve patient outcomes. The advent of rapid deployment valve technology has also been shown to improve morbidity and mortality by reducing cardiopulmonary bypass and aortic cross-clamp times, as well as facilitating the use of minimal access approaches. Rapid deployment valves were introduced into our department at the Royal Infirmary of Edinburgh in 2014. The aim of this study is to investigate if utilising the combination of rapid deployment valves and a mini sternotomy minimally invasive approach resulted in improved outcomes in various patient subgroups. METHODS: Over a 3-year period, we identified 714 patients who underwent isolated AVR in our centre. They were divided into two groups: 61 patients (8.5%) were identified who received rapid deployment AVR via J-shaped mini upper sternotomy (MIRDAVR group), whilst 653 patients (91.5%) were identified who received either a full sternotomy (using a conventional prosthesis or rapid deployment valve) or minimally invasive approach using a conventional valve (CONVAVR group). We retrospectively analysed data from our cardiac surgery database, including pre-operative demographics, intraoperative times and postoperative outcomes. Outcomes were also compared in two different subgroups: octogenarians and high-risk patients. RESULTS: Pre-operative demographics showed that there were significantly more female and elderly patients in the MIRDAVR group. The MIRDAVR group had significantly reduced cardiopulmonary bypass (63.7 min vs. 104 min, p = 0.0001) and aortic cross-clamp times (47.3 min vs. 80.1 min, p = 0.0001) compared to the CONVAVR group. These results were particularly significant in the octogenarian population, who also had a reduced length of ICU stay (30.9 h vs. 65.6 h, p = 0.049). In high-risk patients (i.e. logistic EuroSCORE I > 10%), minimally invasive-rapid deployment aortic valve replacement is still beneficial and is also characterized by significantly shorter cardiopulmonary bypass time (69.1 min vs. 96.1 min, p = 0.03). However, post-operative correlations, such as length of ICU stay, become no more significant, likely due to serious co-morbidities in this patient group. CONCLUSION: We have demonstrated that minimally invasive rapid deployment aortic valve replacement is associated with significantly reduced cardiopulmonary bypass and aortic cross-clamp times. This correlation is much stronger in the octogenarian population, who were also found to have significantly reduced length of ICU stay. Our study raises the suggestion that this approach should be utilised more frequently in clinical practice, particularly in octogenarian patients.

Severe Neurovascular Compromise Associated with Plastic Deformation of Ulna Elastic Nail Following Forearm Re-fracture.

We present a case of periprosthetic re-fracture of the forearm in a child with previous intramedullary elastic nailing of the ulna and plate fixation of the radius for a both-bone forearm fracture. In-situ plastic deformation of the ulna elastic nail resulted in persistent angulation and subsequent severe neurovascular compromise. The angulation was resistant to emergent attempts at closed manipulation and therefore nail removal, open reduction, and internal fixation were performed. At final follow-up, fracture union was demonstrated and there was no residual neurological deficit.

The Hidden Cost of Modern Medical Interventions: How Medical Advances Have Shaped the Prevalence of Human Fungal Disease.

Life expectancy in the West is the highest it has ever been, due to the introduction of better hygiene practices and sophisticated medical interventions for cancer, autoimmunity and infectious disease. With these modern advances, a rise in the prevalence of opportunistic infections has also been observed. These include several fungal infections, which present a particular clinical challenge due to the lack of fungal vaccines, limited diagnostics and increasing antifungal drug resistance. This mini-review outlines how modern-day clinical practices have shaped the recent increase in fungal diseases observed in the last few decades. We discuss new research that has implicated the use of immune-modulating drugs in the enhanced susceptibility of vulnerable patients to life-threatening fungal infections.

Pseudomonas aeruginosa inhibits Rhizopus microsporus germination through sequestration of free environmental iron.

Rhizopus spp are the most common etiological agents of mucormycosis, causing over 90% mortality in disseminated infection. Key to pathogenesis is the ability of fungal spores to swell, germinate, and penetrate surrounding tissues. Antibiotic treatment in at-risk patients increases the probability of the patient developing mucormycosis, suggesting that bacteria have the potential to control the growth of the fungus. However, research into polymicrobial relationships involving Rhizopus spp has not been extensively explored. Here we show that co-culturing Rhizopus microsporus and Pseudomonas aeruginosa results in the inhibition of spore germination. This inhibition was mediated via the secretion of bacterial siderophores, which induced iron stress on the fungus. Addition of P. aeruginosa siderophores to R. microsporus spores in the zebrafish larval model of infection resulted in inhibition of fungal germination and reduced host mortality. Therefore, during infection antibacterial treatment may relieve bacterial imposed nutrient restriction resulting in secondary fungal infections.

Access to the talar dome surface with different surgical approaches.

BACKGROUND: Access to the talar dome for the treatment of osteochondral lesions (OCLs) can be achieved via several different approaches to the ankle joint. The recent description of an anatomical nine-grid scheme of the talus has proven useful to localise OCLs but no studies have demonstrated which approaches are indicated to access each of these zones. The aim of this study is to demonstrate the access afforded to each zone by each approach. METHODS: Four standard soft tissue ankle approaches were performed simultaneously in ten fresh-frozen cadavers (anterolateral - AL, anteromedial - AM, posterolateral - PL, posteromedial - PM). The area of the talus, which was accessible with an instrument perpendicular to the surface was documented for each of the approaches. Using ImageJ software the surface area exposed with each approach was calculated. The talar dome was then divided using a nine-grid scheme and exposure to each zone was documented. RESULTS: The AL, AM, PL and PM approaches allow for exposure of 24%, 25%, 5%, 7% of the talar dome respectively. The AL gives access to zones 3 (completely) and 2, 5, 6 (partially); the AM to zones 1 (completely) and 2, 4, 5 (partially); the PL to zones 9 and 8 (partially); and the PM to zones 7 and 8 (partially). CONCLUSIONS: A large area of the talar dome cannot be easily accessed with the use of standard soft tissue approaches (39%). Minimal or no access is achieved for grid zones 4-6 and 8. In those instances careful preoperative planning is necessary and extended exposure can be achieved with the use of osteotomies, section of the ATFL or through modified approaches.

The dowel technique for first metatarso-phalangeal joint arthrodesis in revision surgery with bone loss.

BACKGROUND: The operative management of failed first metatarso-phalangeal joint (MTPJ) surgery is often complicated by bone loss and shortening of the hallux. Restoration of first ray length and alignment often cannot be achieved with in situ fusion and reconstruction techniques with bone graft are therefore required. We present a novel technique of longitudinal (proximo-distal) bone dowel arthrodesis for first MTPJ arthrodesis with bone loss. METHODS: Between August 2007 and February 2015, eight patients have been treated by the senior author with this technique. The mean age at surgery was 60.5 years (range 45-80) with seven females and one male. Index surgery was MTPJ arthrodesis (three patients), Keller excision arthroplasty (two patients), MTPJ hemiarthroplasty (two patients) and silastic arthroplasty (one patient). Clinical and radiological fusion was assessed and other radiological measurements included hallux valgus angle (HVA) and length of the hallux (LOH). RESULTS: All patients achieved fusion at a mean of 9.3 weeks (range 6-12) from surgery and only one patient required removal of metalwork. There were no major complications. The HVA improved in all cases from 21.4±2.8 pre-operatively to 11.6±3.5 post-operatively (p>0.05). The LOH also increased in all cases from 82.1±8.3mm to 86.7±8.2mm (p>0.05). The subgroup of patients who were revised from an arthroplasty, where maintenance of length rather than increase in length was desirable (hemiarthroplasty, silastic) had significantly lower increase in LOH than those revised from a non-arthroplasty index surgery (arthrodesis, Keller) (p=0.029). CONCLUSION: The dowel technique is successful for first MTPJ arthrodesis revision surgery with optimal union rates and satisfactory radiographic and clinical outcomes. It is an effective and versatile option for managing bone loss and deformity of the hallux.

Management of chronic Achilles tendon ruptures-A review.

Achilles tendon ruptures are increasingly common yet up to a fifth of them are undiagnosed after medical consultation. Those undiagnosed will become chronic ruptures causing considerable functional morbidity and represent a challenge to the treating doctor. The purpose of this article is to discuss the presentation and management of chronic Achilles tendon ruptures. Due to the paucity of data, evidence-based recommendations are unavailable. A number of different surgical techniques are presented and a working algorithm is described to aid in the treatment of these lesions.

Double First Metatarsal and Akin Osteotomy for Severe Hallux Valgus.

BACKGROUND: The technique of double first metatarsal osteotomies was first developed in response to the high frequency of recurrence noted in the treatment of severe adolescent congruent hallux valgus deformities. The concept behind the use of this technique is that it allows the individual correction of each component of the deformity. We have modified the technique for use in adult hallux valgus where the majority of deformities are incongruent deformities and the distal chevron osteotomy is used primarily for its additional translational properties rather than purely to correct the distal metatarsal articular angle (DMAA). We report on a series of double first metatarsal osteotomies (basal opening wedge and distal chevron osteotomy) with Akin osteotomy in the treatment of moderate to severe adult hallux valgus deformity. METHODS: All patients presenting to our institution with a hallux valgus deformity and treated with this procedure between 2008 and 2013 with a minimum of 1 year of follow-up were identified. Data were obtained through review of case notes, electronic charts, and digital imaging. A total of 50 feet in 48 patients underwent double first metatarsal osteotomy with Akin osteotomy. Three patients were excluded due to loss to follow-up, leaving 47 feet in 45 patients with a mean follow-up of 45 months (range, 14-60 months). Of these 43 (96%) were female and the mean age was 56 years (range, 35-70 years). RESULTS: The mean preoperative hallux valgus angle (HVA), intermetatarsal angle (IMA), DMAA, sesamoid position, and lateral first metatarsotalar angle were 42 degrees (range, 32-52 degrees), 18 degrees (range, 6-26 degrees), 12 degrees (range, 4-26 degrees), stage 6 (range, 4-7), and 2 degrees of dorsiflexion (range, 20 degrees of dorsiflexion to 4 degrees of plantar flexion), respectively. The mean postoperative HVA, IMA, DMAA, sesamoid position, and lateral first metatarsotalar angle were 7 degrees (range, 2 to 24 degrees), 4 degrees (range, 4-14 degrees), 6 degrees (range, 10-22 degrees), stage 2 (range, 1-5) and 6 degrees of plantar flexion (range, 8 degrees of dorsiflexion to 18 degrees of plantar flexion), respectively. The osteotomies consolidated at a mean of 7 weeks (range, 5-9 weeks). There were no cases of delayed union or nonunion. Of the cohort, 45 (96%) stated that they were satisfied overall with the results of their surgery and would have it again. The mean postoperative summary index Manchester-Oxford Foot Questionnaire (MOXFQ) score was 12.9 (range, 0-60.9) out of 100 at a mean follow-up of 45 months (range, 14-60 months). For the minority of cases, 8 (17%), that had preoperative scoring, the summary index MOXFQ score was 73.7 (range, 29.7-100). CONCLUSIONS: The double first metatarsal osteotomy (basal opening wedge and distal chevron osteotomy) with Akin osteotomy provides powerful correction and facilitates correction of the individual components of the hallux valgus deformity. The individual osteotomies that make up this procedure are familiar to the majority of foot and ankle surgeons, thus limiting the associated learning curve. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Anatomic structures at risk: curved hindfoot arthrodesis nail--a cadaveric approach.

Retrograde intramedullary nailing of the hindfoot and ankle is an established procedure for salvage of severe foot and ankle deformity, arthritis, tumor, and instability. In the present study, retrograde hindfoot (tibiotalocalcaneal) arthrodesis nailing was performed using a standardized technique on 7 cadaver specimens by trained senior surgeons. The specimens were then dissected to determine the distance of the subcalcaneal structures at risk from the insertion point of the nail. The findings showed that the distance of the lateral neurovascular bundle from the edge of the nail was 6.5 (range 3.5 to 8, 95% confidence interval 5.9 to 7.1) mm. No neurovascular bundle was compromised, and all were within a previously described "safe window."

Transient osteoporosis of the foot.

Transient osteoporosis is a rare cause of pain in the foot. There is a broad differential diagnosis. A multidisciplinary assessment by both an orthopaedic surgeon and rheumatologist with review of the imaging by a radiologist is useful, as this condition is a diagnosis of exclusion.