The surgical correction of hammer digits offers a variety of surgical treatments ranging from arthroplasty to arthrodesis, with many options for fixation. In the present study, we compared 2 buried implants for arthrodesis of lesser digit deformities: a Smart Toe® implant and a buried Kirschner wire. Both implants were placed in a prepared interphalangeal joint, did not violate other digital or metatarsal joints, and were not exposed percutaneously. A retrospective comparative study was performed of 117 digits with either a Smart Toe® implant or a buried Kirschner wire, performed from January 1, 2007 to December 31, 2010. Of the 117 digits, 31 were excluded because of a lack of 90-day radiographic follow-up. The average follow-up was 94 to 1130 days. The average patient age was 61.47 (range 43 to 84) years. Of the 86 included digits, 48 were left digits and 38 were right. Of the digits corrected, 54 were second digits, 24 were third digits and 8 were fourth digits. Fifty-eight Smart Toe® implants were found (15 with 19-mm straight; 2 with 19-mm angulated; 34 with 16-mm straight; and 7 with 16-mm angulated). Twenty-eight buried Kirschner wires were evaluated. No statistically significant difference was found between the Smart Toe® implants and the buried Kirschner wires, including the rate of malunion, nonunion, fracture of internal fixation, and the need for revision surgery. Of the 86 implants, 87.9% of the Smart Toe® implants and 85.7% of the buried Kirschner wires were in good position (0° to 10° of transverse angulation on radiographs). Osseous union was achieved in 68.9% of Smart Toe® implants and 82.1% of buried Kirschner wires. Fracture of internal fixation occurred in 12 of the Smart Toe® implants (20.7%) and 2 of the buried Kirschner wires (7.1%). Most of the fractured internal fixation and malunions or nonunions were asymptomatic, leading to revision surgery in only 8.6% of the Smart Toe® implants and 10.7% of the buried Kirschner wires. Both the Smart Toe® implant and the buried Kirschner wire offer a viable choice for internal fixation of an arthrodesis of the digit compared with other studies using other techniques

Proximal inter-phalangeal joint . (PIPJ). arthrodesis is a commonly performed procedure as a part of hammer and claw-toe correction. Conventional K-wire stabilisation has the potential disadvantages of infection; violation of DIP joint; external protrusion or the wire and necessity of removal. Newer intra-medullary stabilisation devices are also available, though tend to incur addition costs. We present our technique and results of using a single, buried 1.6 mm K-wire for proximal inter-phalangeal joint fusion. Our objectives were to assess union rates and patient satisfaction following intra-medullary K wires for PIP joint fusion. This involved reviewing 26 consecutive patients (34 toes) who had undergone hammer or claw toe correction. Case notes and radiographs were reviewed to establish results and complications and the need for revision surgery. Initial Radiographs taken at 6 weeks and a telephone survey was undertaken to assess patient satisfaction (16–44 weeks). Our findings were that of the twenty-one women and five men underwent surgery, with a mean age of 59 years (24–77), stable union was achieved in 33 of 36 toes. No patients had superficial or deep infection and no patient required wire removal or a revision procedure. In conclusion, PIPJ Arthrodesis with buried K Wires has excellent clinical outcome and high patient satisfaction

Background. Percutaneous K-wire fixation is a well-recognised and often performed method of stabilisation for distal radius fractures. However, there is paucity in the literature regarding the infection rate after percutaneous K-wire fixation for distal radius fractures. Aims. To analyse the rate and severity of infection after percutaneous K-wire fixation for distal radius fractures. Material and methods. Between October 2004 and June 2005, 43 patients with closed distal radius fractures had percutaneous K-wire fixation. The wires were left outside the skin in all the cases for easy removal at the end of six weeks at the clinic. They were followed up in the clinic at 1, 2, 4, and 6 weeks. The pin tracts were examined at 2 weeks and six weeks, or if needed earlier. The severity of pin tract infection was graded using modified Oppenheim classification. Results. Out of 43 patients, the male to female ratio was 13:30. The mean age was 49.1 years (range 5-86 years). There were nine cases of pin tract infection, out of which three were grade I, three were grade II, two were grade III, and one was grade IV. In three cases the K-wires had to be removed earlier. Discussion. The infection rate after percutaneous K-wire fixation for distal radius fractures is high (20.9%), which is equivalent to the infection rate quoted in the literature for hybrid external fixators. As the K-wires are used to fix the fractures, the expected implant infection rate in Trauma and Orthopaedics which is less than 1% should be aimed for. However this is not the case. Hence, burying the K-wires under the skin may be an alternative to reduce the infection rate after percutaneous K-wire fixation of distal radius

Introduction. Bone marrow stimulation has been a successful treatment option in cartilage repair and microfracture was the procedure of choice since the late 1980s. Despite its success in young and active patients, microfracture has inherent shortcomings such as shallow channels, wall compression, and non-standardized depth and diameter. This in vitro study assessed bone marrow access comparing microfracture, 1 and 2mm K-Wires, 1mm drill, and a recently introduced standardized subchondral bone needling procedure (Nanofracture) that creates 9mm deep and 1mm wide channels. Methods. An adult ovine model was used to assess access to bone the marrow spaces as well as effects on bone following microfracture, nanofracture, K-wire, and drilling following ethical clearance. All bone marrow stimulation techniques were conducted on a full thickness articular cartilage defect on the medial femoral condyles by the same surgeon. The same groups were repeated in vitro in 4 paired ovine distal femurs. MicroCT (Inveon Scanner, Siemens, Germany) was performed using 3D reconstruction and 25 micron slice analysis (MIMICS, Materialise, Belgium). Results. Microfracture elicited shallow depth with bone compression surrounding the channels. Trabecular channel access was limited; the channel depth and diameter were non-standardized and highly user and instrument dependent. Nanofracture demonstrated deep cancellous bone perforation with a high number of open trabecular channels. K-Wire drilling with both diameters resulted in well-defined channel walls, outlined by fine osseous deposits. Trabecular channel access was limited. The diameter of bone perforation is standardized, but depth is defined by visual controls. 1mm drill bit reaming demonstrated better osseous evacuation, but still limited trabecular marrow access. Discussion and Conclusion. Nanofracture resulted in thin, fragmented cancellous bone channels without rotational heat generation. Compared to microfracture, drilling and K-Wire stimulation, nanofracture showed superior bone marrow access with multiple trabecular access channels extending 9mm into subchondral bone

The aim of this study is to compare functional, clinical and radiological outcomes in K-wire fixation versus volar fixed-angle plate fixation in unstable, dorsally angulated distal radius fractures. Fifty-four adult patients with an isolated closed, unilateral, unstable, distal radius fracture were recruited to participate in the study. Only dorsally displaced fractures with no articular comminution were included. Patients were randomised to have their fracture treated with either closed reduction and K-wire fixation (3 wires) or fixed-angle volar plating. Both groups were immobilised in a below elbow cast for six weeks. The wires removed in the outpatients at six weeks and both groups were referred for physiotherapy. Independent clinical review was performed at three and six months post injury. Functional scoring was performed using the DASH and Gartland and Werley scoring systems. Radiographs were evaluated by an independent orthopaedic surgeon. Twenty-five patients were treated with a plate and twenty-nine with wires. There were no complications in the plate group. There were 9 complications in the K-wire group with 3 patients requiring a second operation (1 corrective osteotomy for malunion, 1 median nerve decompression and 1 retrieval of a migrated wire). The remaining complications included: 5 pin site infections (3 treated with early pin removal and 2 with oral antibiotics only), and 1 superficial radial nerve palsy. There were no tendon ruptures. Both groups scored satisfactory functional results with no statistical difference. There was a statistically significant difference in the radiological outcomes with the plate group achieving better results. We conclude that in unstable dorsally angulated distal radius fractures volar fixed-angle plate fixation is able to achieve comparable functional results to K-wire fixation with better radiological results and fewer complications. This has resulted in a change in our clinical practice

Fractures of the femoral head are a challenging problem. The most often performed head preserving procedure worldwide is closed reduction and insertion of cannulated screws under fluoroscopic control. The use of navigation is still experimental in general trauma since rigid reference markers must be attached to all fragments. The examined system (Surgix®, Tel Aviv, Israel) is a fluoroscopy based image analysing system. It consists of a workstation and X-ray opaque markers in surgical tools. When the tool is visible in a C-arm shot a trajectory is displayed as additional layer in the image to serve as guidance for the surgeon. Forty synthetic femurs (Synbone®, Malans, Switzerland) were used and placed inside foam to simulate the soft tissue of the thigh. The models were equipped with 4.5mm radio-opaque markers at the fovea capitis femoris as target point. The aim was to bring the tip of a K-wire as close as possible to the target point entering the bone at the lateral base of the greater trochanter in a center-center position. Twenty were done under image guidance and 20 were operated the conventional way. Outcome measures included the accuracy (the distance between the tip of the wire and the target in a CT), the number of guide wire insertions, procedure duration, radiation exposure and learning curve. In the image guided group optimal guide wire placement was accomplished on first pass in 65% of the cases as compared to 5% in the conventional group (p = < 0.0001). The average number of trial and error was significantly lower in the guided group (1.7 vs. 5.8, p = < 0.0001). Consequently the average duration of the guided procedure was significantly shorter (p = 0.0008) along with radiation exposure time reduced by over 70% (p = 0.0002). The guidance system hit averaged 5.8 mm off target as compared to 5.3 mm for the freehand method (p = 0.3319). Image based guidance significantly shortened the procedure, reduced the radiation exposure and the number of trials without changing the surgeons workflow and can be used in trauma cases were reference marker based navigation is not applicable

The internal fixation of scaphoid bone fractures remains technically difficult due to the size of the bone and its three- dimensional shape. Early rigid fixation, e.g with a screw, has been shown to support good functional outcome. In terms of stability of the fracture, biomechanical studies have shown a superior result with central screw placement in the scaphoid in comparison with an eccentric position, which can lead to delayed or non-union. Image-based navigation could be helpful for these cases. The main limitation of reference-based navigation systems is their dependence on fixed markers like used in modern navigation systems. Therefore it is limited in treatment of small bone fractures. In former experimental studies 20 artificial hand specimens were randomised into two groups and blinded with polyurethane foam: 10 were treated conventionally and 10 were image guided. For trajectory guidance a reduction of duration of surgery, radiation exposure and perforation rate compared to the conventional technique could be found. Accuracy was not improved by the new technique. The purpose of this study was to identify the possible advantages of the new guidance technique in a clinical setting. In this prospective, non-randomised case series we tested the feasibility of the system into the accommodated surgical workflow. There was no control group. Three cases of scaphoid fractures were included. All of the patients were treated with a cannulated screw following K-wire placement via the percutaneous volar approach described. In addition, length measurements and screw sizes were determined using special features of the system. The performing surgeon and two attending assistant doctors (one assisting the surgical procedure, one handling the guidance system) had to rate the system following each procedure via a user questionnaire. They had to rate the system's integration in the workflow and its contribution to the success of the surgical procedure in percentages (0 %: totally unsuccessful; 100 %: perfect integration and excellent contribution). All of the clinical procedures were performed by the same surgeon. The surgeons rated the system's contribution and integration as very good (91 and 94 % of 100 %). No adverse event occurred. An average of 1.3 trials ± 0.6 (1; 2) was required to place the K-wire in the fractured scaphoid bone. The dose-area product was 19 cGycm2 ± 3 (16; 22). The mean incision until suture time was 36.7 min ± 5.7 (30; 40). For clinical cases, the system was integrated and rated as very helpful by users. The system is simple and can be easily integrated into the surgical workflow. Therefore it should be evaluated further in prospective clinical series

The use of percutaneous Kirschner wires [K-wires] and plaster is a popular method of treatment for displaced distal radius fracture. However, multi-database electronic literature review reveals unsurprisingly different views regarding their use. From August 2002 till June 2004, 280 distal radial fractures were admitted to our orthopaedic department. They were recorded prospectively in the departmental trauma admissions database. We studied the 87 cases treated with the K-wires and plaster technique. They were classified according to the AO classification system. The mean patient age was 53 [5-88] years. The mean delay before surgery was 7 [0-24] days. We studied the complications reported by the attending orthopaedic surgical team. 48 out of 87 patients [55.1%] were reported to have complications. We analysed the displacement and the pin tract infection, as they were the main reported complications. 28 out of 87 patients [32%] had displacement [9 had further surgery to correct the displacement, 19 did not have any further surgery as the displacement was accepted]. 11 out of 87 patients [12.6%] had pin tract infection [7 needed early removals of the K-wires and systematic treatment]. Further analysis showed no statistically significant relation between the complications rate and the age of the patients, the delay before surgery or the type of the fractures. We demonstrate a considerable high displacement and infection rate with the use of K-wires and plaster technique for fixation of distal fracture irrespective of the age of the patients, the delay before surgery or the fracture classification. There are other methods for fixation of the distal radial fracture with proven less morbidity which should be considered

Many surgical procedures have been put forth for the management of AC disruption none of them proved to be preferred surgical procedure. To provide better surgical stabilization and functional outcome for the management of AC joint disruption. Study period from 2015 to 2017, total of 14 patients presented with AC joint disruption, patients underwent ethibond fixation and reinforcement with K wire.

Out of 14 patients 10 patients participated in the study. The procedure was stabilization of the AC joint by passing the ethibond suture material around the coracoid process and passing through two drill holes made in the clavicle at the attachment of the coracoclavicular ligament. The stabilization was reinforced by passing K wire through the acromion into the lateral end clavicle. After 3 weeks of surgery, K wire was removed and patient was mobilized. Results were assessed by Constant – Murley score. Patients were followed up for 1 year, the mean Constant – Murley score was 86. One patient had infection at the site of k wire entry, another patient had decreased range of movements at the shoulder. No implant back out, no incidence of dislocation were observed.

This method proves to be better alternative fixation as compared to only K wire fixation and also it avoids the blow out of clavicle while drilling to pass semitendon as clavicle in Indian population is relatively thinner. This procedure offers better stabilization, less morbidity and improved functional outcome as compared to the other various surgical procedures.

Introduction

A prospective study was done using Kirschner (K) wires to internally fix capitellum fractures and its results were analysed.

Distal interphalangeal joint (DIPJ) fusion using a k-wire has been the gold standard treatment for DIPJ arthritis. Recent studies have shown similar patient outcomes with the headless compression screws (HCS), however there has been no cost analysis to compare the two. Therefore, this study aims to 1) review the cost of DIPJ fusion between k-wire and HCS 2) compare functional outcome and patient satisfaction between the two groups. A retrospective review was performed over a nine-year period from 2012-2021 in Counties Manukau. Cost analysis was performed between patients who underwent DIPJ fusion with either HCS or k-wire. Costs included were surgical cost, repeat operations and follow-up clinic costs. The difference in pre-operative and post-operative functional and pain scores were also compared using the patient rate wrist/hand evaluation (PRWHE). Of the 85 eligible patients, 49 underwent fusion with k-wires and 36 had HCS. The overall cost was significantly lower in the HCS group which was 6554 New Zealand Dollars (NZD), whereas this was 10408 NZD in the k-wire group (p<0.0001). The adjusted relative risk of 1.3 indicate that the cost of k-wires is 1.3 times more than HCS (P=0.0053). The patients’ post-operative PRWHE pain (−22 vs −18, p<0.0001) and functional scores (−38 vs −36, p<0.0001) improved significantly in HCS group compared to the k-wire group. Literatures have shown similar DIPJ fusion outcomes between k-wire and HCS. K-wires often need to be removed post-operatively due to the metalware irritation. This leads to more surgical procedures and clinic follow-ups, which overall increases the cost of DIPJ fusion with k-wires. DIPJ fusion with HCS is a more cost-effective with a lower surgical and follow-up costs compared to the k-wiring technique. Patients with HCS also tend to have a significant improvement in post-operative pain and functional scores

Abstract. A study was done to test the strength of various configurations of tension band wiring (TBW) and we report clinical results of ‘Horizontal Figure of Eight TBW’ (H – 8 TBW). In an experimental lab, a model of the fractured patella was mounted on a Nene tensile testing machine and various configurations of TBWs were tested in different positions of Kirschner wires. The strength of TBW and various knots securing the ends of wires were analysed on load/displacement graphs. The experimental results were compared with the theoretical results using trigonometry and mathematical equations. Since 1986, H – 8 TBW (Sonanis and Bhende modification) was used clinically in 42 patients (40 fractured patella, and 2 greater trochanteric osteotomies) in 26 males and 16 females and all patients were followed up to average 18 months. Experimentally H – 8 TBW (0.8mm wire) could resist maximum distraction force of 700 N and achieved maximum compression. Placement of the two Kirschner wires at the mid way between centre and edge of patella at the level of fracture site achieved optimum rotational stability and compression. Crimping method of gripping the ends of wires was the most secured method (120 N). Clinically bony union using H-8 TBW was achieved in all 41 patients. Complications seen were wire discomfort in 3 patients and one death. We conclude that H – 8 TBW achieved maximum compression, optimum K wire placement was at the 1/4th distance from the edge of the patella, and crimping the ends of wire secured best fixation

Aims. To determine the impact of COVID-19 on orthopaediatric admissions and fracture clinics within a regional integrated care system (ICS). Methods. A retrospective review was performed for all paediatric orthopaedic patients admitted across the region during the recent lockdown period (24 March 2020 to 10 May 2020) and the same period in 2019. Age, sex, mechanism, anatomical region, and treatment modality were compared, as were fracture clinic attendances within the receiving regional major trauma centre (MTC) between the two periods. Results. Paediatric trauma admissions across the region fell by 33% (197 vs 132) with a proportional increase to 59% (n = 78) of admissions to the MTC during lockdown compared with 28.4% in 2019 (N = 56). There was a reduction in manipulation under anaesthetic (p = 0.015) and the use of Kirschner wires (K-wires) (p = 0.040) between the two time periods. The median time to surgery remained one day in both (2019 IQR 0 to 2; 2020 IQR 1 to 1). Supracondylar fractures were the most common reason for fracture clinic attendance (17.3%, n = 19) with a proportional increase of 108.4% vs 2019 (2019 n = 20; 2020 n = 19) (p = 0.007). While upper limb injuries and falls from play apparatus, equipment, or height remained the most common indications for admission, there was a reduction in sports injuries (p < 0.001) but an increase in lacerations (p = 0.031). Fracture clinic management changed with 67% (n = 40) of follow-up appointments via telephone and 69% (n = 65) of patients requiring cast immobilization treated with a 3M Soft Cast, enabling self-removal. The safeguarding team saw a 22% reduction in referrals (2019: n = 41, 2020: n = 32). Conclusion. During this viral pandemic, the number of trauma cases decreased with a change in the mechanism of injury, median age of presentation, and an increase in referrals to the regional MTC. Adaptions in standard practice led to fewer MUA, and K-wire procedures being performed, more supracondylar fractures managed through clinic and an increase in the use of removable cast. Cite this article: Bone Joint Open 2020;1-7:424–430

Previous studies describing drill trajectory for single incision distal biceps tendon repair suggest aiming ulnar and distal (Lo et al). This suggests that the starting point of the drill would be anterior and radial to the anatomic insertion of the distal biceps tendon. Restoration of the anatomic footprint may be important for restoration of normal strength, especially as full supination is approached. To determine the safest drill trajectory for preventing injury to the posterior interosseous nerve (PIN) when repairing the distal biceps tendon to the ANATOMIC footprint through a single-incision anterior approach utilising cortical button fixation. Through an anterior approach in ten cadaveric specimens, three drill holes were made in the radial tuberosity from the centre of the anatomic footprint with the forearm fully supinated. Holes were made in a 30º distal, transverse and 30º proximal direction. Each hole was made by angling the trajectory from an anterior to posterior and ulnar to radial direction leaving adequate bone on the ulnar side to accommodate an eight-millimetre tunnel. Proximity of each drill trajectory to the PIN was determined by making a second incision on the dorsum of the proximal forearm. A K-wire was passed through each hole and the distance between the PIN and K-wire measured for each trajectory. The PIN was closest to the trajectory K-wires drilled 30° distally (mean distance 5.4 mm), contacting the K-wire in three cases. The transverse drill trajectory resulted in contact with the PIN in one case (mean distance 7.6 mm). The proximal drill trajectory appeared safest with no PIN contact (mean distance 13.3 mm). This was statistically significant with a Friedman statistic of 15.05 (p value of 0.00054). When drilling from the anatomic footprint of the distal biceps tendon the PIN is furthest from a drill trajectory aimed proximally. The drill is aimed radially to minimise blowing out the ulnar cortex of the radius. For any reader inquiries, please contact . vansurgdoc@gmail.com

The treatment of paediatric supracondylar humeral fractures is likely one of the first procedures involving X-ray guided wire insertion that trainee orthopaedic surgeons will encounter. Pinning is a skill that requires high levels of anatomical knowledge, spatial awareness, and hand-eye coordination. We developed a simulation model using silicone soft-tissue and 3D-printed bones to allow development and practice of this skill at no additional risk to patients. For this model, we have focused on reusability and lowering raw-material costs without compromising fidelity. To achieve this, the initial bone model was extracted from open-source computed tomography scans and modified from adult to paediatric size. Muscle of appropriate robustness was then sculpted around the bones using 3D modelling software. A cutaneous layer was developed to mimic oedema using clay sculpturing on a plaster-casted paediatric forearm. These models were then used for 3D-printing and silicone casting respectively. The bone models were printed with settings to imitate cortical and cancellous densities and give high-fidelity tactile feedback upon drilling. Each humerus costs NZD $0.30 in material to print and can be used 1–3 times. Silicone casting of the soft-tissue layers imitates differing relative densities between muscle and oedematous cutaneous tissue, thereby increasing skill necessary to accurately palpate landmarks. Each soft-tissue sleeve cost NZD $70 in material costs to produce and can be used 20+ times. The resulting model is modular, reusable, and replaceable, with each component standardised and easily reproduced. It can be used to practice land-mark palpation and Kirschner wire pinning and is especially valuable in smaller centres which may not be able to afford traditional Saw Bones models. This low-cost model thereby improves equity while maintaining quality of simulation training

Aim. To describe a 2-stage treatment pathway for managing neuropathic forefoot ulcers and the safety and efficacy of percutaneous tendo-Achilles lengthening (TAL) in out-patient clinics. Methods. Forefoot ulcers in patients with diabetic neuropathy are a result of factors that result in increased forefoot plantar pressure. Plantar flexed metatarsal heads secondary to progressive claw toe deformity and hindfoot equinus from changes within the gastrocnemius-soleus-tendo-Achilles complex, with additional contraction of tibialis posterior and peroneal longus, secondary to motor neuropathy results in progressive increase in forefoot plantar pressures. Consecutive patients, who presented to our Diabetic Foot clinic since February 2019 with forefoot ulcers or recurrent forefoot callosity were treated with TAL in the first instance, and in patients with recurrent or non-healing ulcers, by proximal dorsal closing wedge osteotomy; a 2-stage treatment pathway. Patients were followed up at 3, 6, and 12 months to assess ulcer healing and recurrence. Results. One hundred and twelve patients (146 feet) underwent TAL by 3 consultants in the out-patient clinics. Of these, 96 feet were followed for a minimum of 12 months (range 12–36 months). None had infection or wound related problems at the tenotomy sites; complete transection of the tendon was noted in 4 patients (4%) and one-patient developed heel callosity suggestive of over-lengthening. In 92 feet (96%), the ulcers healed within 10 weeks (± 4 weeks). Additional z-lengthening of peroneal longus and tibialis posterior tendons helped in patients with big-toe and 5. th. metatarsal head ulcers. In 12 feet (10%), the ulcer failed to heal or recurred, the MRI scan in these patients showed plantar flexed metatarsals secondary to progressive claw toe deformity. The ulcer in this group healed after surgical offloading with proximal dorsal closing wedge osteotomy. In patients with osteomyelitis, the intramedullary canal was curetted and filled with local antibiotic eluting agents such as Cerament G. ®. The osteotomy site was stabilised with a percutaneous 1.6mm k-wire. Conclusion. The described 2-stage treatment pathway results in long-term healing of neuropathic forefoot ulcers, and in 96% of patients, the ulcer healed after out-patient percutaneous TAL alone. TAL is a safe and effective initial out-patient procedure with improved patient outcomes

Aim. Galleria mellonella larvae is a well-known insect infection model that has been used to test the virulence of bacterial and fungal strains as well as for the high throughput screening of antimicrobial compounds against infections. Recently, we have developed insect infection model G. mellonella larvae to study implant associated biofilm infections using small K-wire as implant material. Here, we aimed to further expand the use of G. mellonella to test other materials such as bone cement with combination of gentamicin to treat implant-associated infections. Method. The poly methyl methacrylate (PMMA) with and without gentamicin and liquid methyl methacrylate (MMA) were kindly provided by Heraeus Medical GmbH, Wehrheim. To make the bone cement implants as cubes, Teflon plate (Karl Lettenbauer, Erlangen) with specified well size was used. The Radiopaque polymer and monomer were mixed well in a bowl, applied over on to the Teflon plate and pressed with spatula to form fine and uniform cubes. After polymerization, the bone cement implants were taken out of the Teflon well plate with the help of pin. For the infection process, bone cement cubes were pre-incubated with S. aureus EDCC 5055 culture at 5×10. 6. CFU/ml for 30 min at 150 rpm shaking conditions. Later, these implants were washed with 10ml PBS and implanted in the larvae as mentioned. Survival of the larvae were observed at 37°C in an incubator. To analyze the susceptibility of the bacterial infections towards gentamicin, survival of the larvae compared with control group implanted only with bone cement. The effect of gentamicin was also measured in terms of S. aureus load in larvae on 2. nd. day. SEM analysis was performed to see the effect of gentamicin on biofilm formation on bone cement. Results. Our experiments established the G. mellonella as an excellent model to screen bone cement with antimicrobial compounds against bacterial infections. The gentamicin bone cement samples showed excellent S. aureus bacterial load reduction after the implantation in G. mellonella model. The bone cement with gentamicin showed better survival of larvae infected with S. aureus compared to control. Finally, the gentamicin also affected the biofilm formation on the bone cement surface with S. aureus. Conclusions. Thus, our work showed G. mellonella is a rapid, cheap economical pre-clinical model to study the bone cement associate bacterial infections as well as screening of the various antimicrobial compounds

Aim. Fungal periprosthetic joint infections are difficult to treat and often associated with a limited outcome for patients. Candida species account for approximately 90% of all fungal infections. In vivo biofilm models play major role to study biofilm development, morphology, and regulatory molecules for bacteria. However, in vivo modeling of biofilm-associated fungi models are very rare. Furthermore, due to ethical restrictions, mammalian models are replaced with other alternative models in basic research. Recently, we have developed insect infection model G. mellonella larvae to study implant associated biofilm infections with bacteria. This model organism was not used for fungi biofilm infection yet. Thus, we aimed to establish G. mellonella as in vivo model to study fungal implant infections using Candida albicans as model organism and to test anti-fungal medication. Method. Titanium and Stainless steel K-wires were cut into small pieces with size of 4mm. For the infection process, implants were pre-incubated in specified fungal growth culture Candida albicans at 1×10. 7. CFU/ml for 30 min at 150 rpm shaking conditions. Later, these implants were washed with 10ml PBS and implanted in the larvae as mentioned. To analyze the susceptibility of the implant-associated fungal infections towards anti fungal compounds, the larvae were treated with amphotericin B, fluconazole and voriconazole after 24h of implantation. The effect of anti-fungal compounds was measured in terms of survival observation for 5 days and fungal load in larvae on 2. nd. day. To reveal the fungal biofilm formation on implant, the implants were removed on day 3 and processed for SEM analysis. Results. Pre-incubated K-wire caused the Candida infection and observed the death of the larvae. The treatment with antifungal compounds recovered the larvae from the implant-infection, except in case of Voriconazole. However, the recovery with treatment of anti fungal compounds was not effective as the larvae with planktonic infection, which highlights typical biofilm phenotype. Further, the treatment with anti-fungal compounds with Amphotericin B and Fluconazole reduced the fungal load in larvae tissue. The SEM analysis revealed the formation fungal biofilm with hyphae and spores associated with larvae tissue on implant surface. Conclusions. The results from survival analysis, antifungal treatment and SEM analysis are very promising to use of G. mellonella as in vivo model to study fungal infections on implanted materials. Our study highlights the use of G. mellonella larvae as alternative in vivo model to study implant-associated fungal infections that reduces the use of the higher mammals

Optimal alignment of the acetabular cup component is crucial for good outcome of total hip arthroplasty [THA]. Increased accuracy of implant positioning may improve clinical outcome. To achieve this, patient specific instrumentation was developed. A patient-specific guide manufactured by 3D printing was designed to aid in positioning of the cup component with a pre-operatively defined anteversion and inclination angle. The guide fits perfectly on the acetabular rim. An alignment K-wire in a pre-operatively planned orientation is used as visual reference during cup implantation. Accuracy of the device was tested on 6 cadaveric specimens. During the experiment, cadavers were positioned for a THA procedure using a posterolateral approach. A normal-sized incision was made and approach used as in the conventional surgical procedure. The PSI was subsequently fitted onto the acetabular rim and secured into its unique position due to its patient specific design. The metallic pin was placed in a drill hole of the PSI. Post-operative CT image data of each acetabulum with the placed pin were transferred to Mimics and the 3D model was registered to the pre-operative one. The anteversion and inclination of the placed pin was calculated and compared to the pre-operatively planned orientation. The absolute difference in degrees was evaluated. A secondary test was carried out to assess the error during impaction while observing the alignment K-wire as a visual reference. In a laboratory setting, error during impaction with a visual reference of the K-wire was measured. Deviation from planning showed to be on average 1.04° for anteversion and 2.19° for inclination. By visually aligning the impactor with this alignment K-wire, the surgeon may achieve cup placement as pre-operatively planned. The effect of the visual alignment itself was also evaluated in a separate test-rig showing minimal deviations in the same range. The alignment validation test resulted in an average deviation of 1.2° for inclination and 1.4° for anteversion between the metallic alignment K-wire used as visual reference and the metallic K-wire impacted by the test subjects. The inter-user variability was 0.9° and 0.8° for anteversion and inclination respectively. The intra-user variability was 1.6° and 1.0° for anteversion and inclination respectively. Tests per test subject were conducted in a consecutive manner. We investigated the accuracy of two factors affecting accuracy in the cup insertion with PSI, i.e. accuracies of the errors of bony fitting and cup impaction. Since the accuracy of the major contributing factors to the overall accuracy of PSI for cup insertion with linear visual reference of a metallic K-wire was within the acceptable range of 2 to 3 degrees, we state that the PSI we have designed assists to achieve the preoperatively planned orientation of the cup and as such leads to the reduction of outliers in cup orientation. This acetabular cup orientation guide can transfer the pre-operative plan to the operating room

Aim. To investigate the ability of the bacteriophage Sb-1 to treat and prevent implant-associated infections due to methicillin-resistant Staphylococcus aureus (MRSA) in Galleria mellonella larvae implanted with a K-wire. Method. The stability of Sb-1 in G. mellonella larvae was investigated by injecting a phage titer of 10. 8. PFU and evaluating the presence of Sb-1 in hemolymph at different time points. For infection experiments, sterile stainless-steel K-wires (4 mm, 0.6 mm Ø) were implanted into larvae. Two days after implant, larvae were infected with MRSA ATCC 43300 (1×10. 5. CFU) and incubated at 37°C for further 2 days. Implanted-infected larvae were thus treated for 2 days (3×/day) with 10µL of: i) PBS; ii) Sb-1 (10. 7. PFU); iii) Daptomycin (4mg/kg), iv) PBS (24h)/Daptomycin(24h); v) Sb-1(24h)/Daptomycin(24h). To evaluate the prophylactic efficacy of Sb-1, an experiment based on phages or vancomycin (10mg/kg) administration, followed by MRSA infection of implanted larvae was performed. Both two days post-infection and post-treatment, K-wires were explanted, and the material was sonicated and plated for MRSA colony counting. Results. Sb-1 titer resulted stable in hemolymph of G. mellonella larvae for 6–8 h post-administration. Two days post-infection of K-wire implanted larvae, ≈5×10. 7. CFU/ml MRSA were found on the material. K-wires from larvae treated with Sb-1 or Daptomycin showed a MRSA CFU/ml reduction of ≈1 log compared to the CFU/ml values of the untreated control. The staggered administration Sb-1/Daptomycin determined higher CFU reduction (≈ 3.5 log). Prophylaxis with Sb-1 prevented MRSA infection of 7out of 10 larvae similarly to vancomycin. Conclusions. G. mellonella larvae implanted with K-wires are a suitable model to test antibiofilm formulations in vivo. Sb-1 phage is able to prevent implant-associated infection due to MRSA in larvae. Sequential combination of Sb-1 and Daptomycin strongly reduces the MRSA load on implanted K-wires