Introduction. This study aimed to assess the relationship between preparation times and operative procedures for elective orthopaedic surgery. A clearer understanding of these relationships may facilitate list organisation and thereby contribute to improved operating theatre efficiency. Methods. Two years of elective orthopaedic theatre data was retrospectively analysed. The hospital medical information unit provided de- identified data for 2015 and 2016 elective orthopaedic cases, from which were selected seven categories of procedures with sufficient numbers to allow further analysis - primary hip and knee replacement, spinal surgery, shoulder surgery (excluding shoulder replacement), knee surgery, foot and ankle surgery (excluding ankle replacement), Dupuytrens surgery and general orthopaedic surgery. The data analysed included patient age, ASA grade, operation, operation time, and preparation time (calculated as the time from the start of the anaesthetic proceedings to the patient's admission to Recovery, with the operating time [skin incision to skin closure] subtracted). Statistical analysis of the data was undertaken. Results. A total of 1596 procedures performed over the two year period were analysed. Preparation times for the different procedures were assessed, along with the relationship to the procedure complexity. Neither age nor ASA correlated strongly with preparation times. Spine procedures had greater preparation times than hip and knee arthroplasty. Greater uniformity in preparation times for hip and knee arthroplasty was seen across the anaesthetic group than operative times across the surgeon group. Discussion. Preparation times are just one aspect that may be evaluated with regard to theatre utilisation. This study did not address the theatre turn-over time between cases, which includes transfer of the patient from the admitting/pre-operative area into the theatre. Conclusion. Preparation times for elective procedures follow a pattern which may be used to inform list planning, with the potential for greater theatre efficiencies with regard to list utilisation and staff allocation

To document and assess the available evidence regarding single bundle, hamstrings autograft preparation techniques for Anterior Cruciate Ligament reconstruction (ACLR) and provide graft preparation options for different clinical scenarios. Three online databases (Embase, PubMed and Ovid [MEDLINE]) were searched from database inception until April 10, 2021. The inclusion criteria were English language studies, human studies, and operative technique studies for single bundle hamstrings autograft preparation for ACLR. Descriptive characteristics, the number of tendons, number of strands, tendon length, graft length and graft diameter were recorded. The methodological quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) instrument and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system for non-randomized and randomized studies, respectively. The initial search yielded 5485 studies, 32 met the inclusion criteria. The mean MINORS score across all nonrandomized studies was 8.2 (standard deviation, SD 6.6) indicating an overall low quality of evidence. The mean MINORS score for comparative studies was 17.4 (SD 3.2) indicating a fair quality of evidence. The GRADE assessment for risk of bias in the randomized study included was low. There were 2138 knees in 1881 participants, including 1296 (78.1%) males and 363 (21.9%) females recorded. The mean age was 30.3 years. The mean follow-up time was 43.9 months when reported (range 16-55 months). Eleven studies utilized the semitendinosus tendon alone, while 21 studies used both semitendinosus and gracilis tendons. There were 82 (3.8%) two-strand grafts, 158 (7.4%) three-strand grafts, 1044 (48.8%) four-strand grafts, 546 (25.5%) five-strand grafts, and 308 (14.4%) six-strand grafts included. Overall, 372 (19.7%) participants had a single-tendon ACLR compared to 1509 (80.2%) participants who had a two-tendon ACLR. The mean graft diameter was 9.4mm when reported. The minimum semitendinosus and gracilis tendon lengths necessary ranged from 210-280mm and 160-280mm respectively. The minimum graft length necessary ranged from 63-120mm except for an all-epiphyseal graft in the paediatric population that required a minimum length of 50mm. The minimum femoral, tibial, and intra-articular graft length ranged from 15-25mm, 15-35mm and 20-30mm respectively. Thirteen studies detailed intra-operative strategies to increase graft size such as adding an extra strand or altering the tibial and/or femoral fixation strategies to shorten and widen the graft. Two studies reported ACL reinjury or graft failure rate. One study found no difference in the re-injury rate between four-, five- and six-strand grafts (p = 0.06) and the other found no difference in the failure rate between four- and five- strand grafts (p = 0.55). There was no difference in the post-operative Lysholm score in 3 studies that compared four- and five-strand ACLR. One of the five studies that compared post-operative IKDC scores between graft types found a difference between two- and three- strand grafts, favoring three-strand grafts. There are many single bundle hamstrings autograft preparation techniques for ACLR that have been used successfully with minimal differences in clinical outcomes. There are different configurations that may be utilized interchangeably depending on the number, size and length of tendons harvested to obtain an adequate graft diameter and successful ACLR

Background. Cemented femoral stems have an excellent long-term outcome. Modern cement techniques should be used to optimize femoral stem fixation. Bleeding from the bone surface during cemented hip arthroplasty compromises the bone-cement interface. However, no studies have examined this bleeding in vivo nor the effect the different cleaning methods used. In the present study we evaluated bleeding patterns and efficacy of cleaning methods used in third generation cementing techniques. Methods. We prospectively performed a medulloscopy with a 10 mm laparoscope in 200 primary hip arthroplasties. Intramedullary bleeding was evaluated after femoral canal preparation and use of the different cleaning methods. The femoral canal was divided into three areas to facilitate comparison. The intramedullary bleeding was standardized on a four point scale. A non-parametric repeated measures ANOVA was used for statistical analysis. Results. Cotton swabs and brushes did not reduce the intramedullary bleeding significantly after broaching of the canal. Compared to these standard cleaning methods, pulsed lavage and the addition of brushing provided better blood removal (p<0.001). There was a trend, although not statistical significant (p=0.24), towards better canal cleaning if a canal filling tampon with suction was added. Arterial bleeding originating from the posterior wall of the canal was noticed in 26 cases (13 percent). These could only be controlled by diathermy tools. Conclusion. Most standard preparation techniques are insufficient to prepare the femoral canal before cement insertion. In case of severe intramedullary bleeding, an arterial bleeding should be ruled out and if necessary treated with the aid of diathermy tools. We recommend pulsed lavage combined with a brush and a canal filling tampon for femoral canal preparation in cemented primary hip arthroplasty for optimal reduction of intramedullary bleeding

Lavage and preparation of cancellous bone surface is essential to ensure adequate fixation of components in cemented total knee arthroplasty (TKA). Commonly used techniques for bone preparation such as pulse lavage, apart from adding to the cost, may cause local loss of loose cancellous bone and may even drive contaminants deeper into the tissue when used during TKA. We describe a simple, inexpensive and effective tool of using a sterilised toothbrush for preparing bone surface during cemented TKA

Lavage and preparation of cancellous bone surface is essential to ensure adequate fixation of components in cemented total knee arthroplasty (TKA). Commonly used techniques for bone preparation such as pulse lavage, apart from adding to the cost, may cause local loss of loose cancellous bone and may even drive contaminants deeper into the tissue when used during TKA. We describe a simple, inexpensive and effective tool of using a sterilised toothbrush for preparing bone surface during cemented TKA

Introduction:. Despite all the attention to new technologies and sophisticated implant designs, imperfect surgical technique remains a obstacle to improving the results of total knee replacement (TKR). On the tibial side, common errors which are known to contribute to post-operative instability and reduced function include internal rotation of the tibial tray, inadequate posterior slope, and excessive component varus or valgus. However, the prevalence of each error in surgeries performed by surgeons and trainees is unknown. The following study was undertaken to determine which of these errors occurs most frequently in trainees acquiring the surgical skills to perform TKR. Materials and Methods:. A total of 43 knee replacement procedures were performed by 11 surgical trainees (surgical students, residents and fellows) in a computerized training center. After initial instruction, each trainee performed a series of four TKR procedures in cadavers (n = 2) and bone replicas (n = 2) using a contemporary TKR instrument set and the assistance of an experienced surgical instructor. Prior to each procedure, computer models of each cadaver and/or bone replica tibia were prepared by reconstructing CT scans of each specimen. All training procedures were performed in a navigated operating room using a 12 camera motion analysis system (Motion Analysis Inc.) with a spatial resolution in all three orthogonal directions of ± 0.15 mm. The natural slope, varus/valgus alignment, and axial rotation of the proximal tibial surface were recorded prior to surgery and after placement of the tibial component. For evaluation of all data, acceptable limits for implantation were defined as: posterior slope: 0–10°; varus/valgus inclination of tibial resection: ± 3°; and external rotation: 0–10°. Results:. The tibial component was implanted with an average posterior slope of 3.4° ± 3.4°. In 83% of trials, the trainees cut the tibia with less posterior slope than intended (average shortfall: 2.0° ± 4.0°). In 14% of cases the tibial resection sloped anteriorly, whereas in another 5% the posterior slope exceeded 10°. The coronal alignment of the tibial osteotomy averaged 0.1° ± 2.9° of valgus, with 19% of components were implanted in more than 3° of valgus vs. 14% varus (>3°). The average rotational orientation of the tibial component was 5.4° ± 5.3° of external rotation. Overall, 21% of components were placed in internal rotation, and a further 29% in more than 10° of external rotation. Rotational malalignment of the tibial component was the most common error in technique encountered in the study population. Conclusion:. 1. Tibial preparation still presents significant difficulty to many less experienced surgeons, despite the use of modern instrumentation and careful didactic instruction. 2. The most prevalent error in tibial preparation in TKR is malrotation of the tibial component, especially in internal rotation. 3. The errors measured in the computerized bioskills lab replicate clinical cases often presenting with symptoms necessitating early revision. 4. Greater attention is needed to training of surgical skills and intraoperative assessment of sources of technical error, such as component position to improve clinical outcomes of TKR

Introduction. The advantages of the direct anterior approach (DAA) for total hip arthroplasty include the preservation of external rotators and hip abductors thus leading to quicker recovery times. To our knowledge, there is no objective method in the literature to predict the level of difficulty for femoral exposure through the DAA. It would be beneficial to the surgeon learning the DAA to assess difficulty pre-operatively to avoid prolonged operative times. The purpose of this study was to develop a predictive model of femoral exposure difficulty in the DAA using a combination of demographic data and radiographic measurements. Methods. 305 post-operative radiographs of consecutive THA's in patients (184 female, 120 male) with primary or secondary osteoarthritis, mean age 64.6 (range 26–91, SD=11.43) performed through the DAA by one of the co-investigators from 12/2005 to 12/2009 were retrospectively reviewed by two separate observers. The observers were blinded to the difficulty level of femoral exposure. Standard post-operative AP pelvis films were assessed with TraumaCad software (TraumaCad 2.2, Voyant Health, Columbia, MD) to make radiographic measurements as shown in Figure 1–2. Each radiograph was calibrated using the size of the femoral head implant. Exclusion criteria included films that had inadequate coverage of the entire pelvis, mal-rotation, or poor exposure. Statistical analysis was performed using STAT 9.1 (StatCorp; College Station, Texas, USA). A two-sided Kruskal–Wallis test was utilized for non-parametric data. Chi-squared tests and Fisher's Exact Test were used to compare proportions. Statistically significant associations were then added to a multivariate model predicting an outcome of difficult exposure. Results. The difficult exposures were equally distributed throughout the study period. The side of the THA was not associated with a difficult exposure (χ. 2. =0.5516, p=0.968) whereas 66% of difficult cases were male (χ. 2. =38.5323, p=0.0001). Height, weight, BMI, and age were all independent predictors of a difficult exposure, with taller (>175cm) more difficult than shorter (p=.0001), heavier (>100kg) more difficult than lighter (p=.0001), higher BMI (>32) being more difficult than lower BMI (p=.0001), and younger age (<60) being more difficult than older age (p=.003). Radiographic criteria that were predictive of difficult femoral preparation were decreased distance (<110mm) between teardrop signs (p=.0001), increased distance (>211mm) between each SLA (p=0.013), and increased distance (>306mm) between the GT (p=.007). The distance between each ASIS (p=0.375), ASIS to GT (p=.191), and ASIS to SLA (p=.191) were not predictive of difficult femoral preparations. From this, we determined a simple pre-operative scoring tool which allows the surgeon to predict difficult femoral preparations with an 87% sensitivity and easy preparations with >95% specificity. Conclusion. The DAA approach has proven difficult to learn for many surgeons. Careful patient selection can facilitate the learning curve and improve patient outcomes. We describe a simple to implement preoperative rating scale, which gives the surgeon learning DAA an algorithm for appropriate patient selection. Selecting the appropriate patient can reduce the risks to the patient and minimize the cost to society of integrating new surgical techniques

Introduction. Good outcomes in reverse shoulder arthroplasty (RSA) rely in part on stability of the humeral component. Traditionally humeral components have been cemented, however there has been recent interest in press-fit fixation of humeral components in RSA. Lateralization of the head center in RSA can impart larger moments on the humeral component than for anatomic reconstructions, increasing the importance of distal humeral canal preparation for implant stability. To date, the primary stability of any type of press-fit humeral prosthesis has been largely unexplored. The goal of this study is to evaluate the effect of over-reaming the distal humeral canal in a press-fit humeral component in RSA. Methods. Computed tomography (CT) data of the shoulder were obtained from 55 shoulders. Images were segmented to produce digital models of the humerus. Humeral components for RSA (2mm diameter size increments) were sized and placed per the surgical technique, including preparation of the humerus with the appropriate reamers (1mm increments). Finite element models for each specimen were created with heterogeneous bone properties derived from the CT scan. Pressfit between the bone and stem was resolved to quantify the initial contact pressure on the stem; each stem was then loaded at 566N oriented 20° lateral and 45° anterior. Overall motion of the stem was measured, as well as interfacial micromotion in the porous coating region (Fig. 1). The effect of line-to-line (L2L) reaming and over-reaming by 1 mm was evaluated using an unpaired Student's t-test, with significance defined at p<0.05. Results. Across all specimens, stem sizes 8 (n=3), 10 (n=25), 12 (n=20), 14 (n=2), and 16 (n=1) were used. Stem motion ranged from approximately 250–750μm; micromotion remained under 300μm (Fig. 2). Stem motion was significantly less for L2L reaming as compared to over-reaming for both size 10 (p=.008) and size 12 (p=.002) stems; micromotion was significantly less for size 12 (p=.002) stems. L2L reaming to a larger diameter stem resulted in significantly reduced stem motion (average 390μm versus 530μm, p<.001) and micromotion (average 53μm versus 135μm, p=.001) than over-reaming and using a smaller diameter stem. Stem rotation following L2L reaming was generally below 0.5°, and exceeded 0.75° when over-reaming. Discussion and Conclusion. Reaming of the humeral canal directly impacts the stability of humeral stems in RSA. Even with satisfactory proximal press-fit, over-reaming enables increased rotation of the stem under functional loading prior to cortical engagement, and results in increased micromotion. In cases in which the reamer and stem offerings result in over-reaming, L2L reaming to the next larger stem significantly reduces stem motion and micromotion. However, reaming up also removes distal cortical bone, and thus the strength of the prepared humerus must be considered. In conclusion, line-to-line reaming significantly reduces the micromotion of humeral stems as compared to over-reaming

Purpose. The purpose of this study is to inspect balance of the pelvis in the acetabular operation of total hip arthroplasty (THA) using direct anterior approach (DAA), and it is to examine precision of the acetabular socket setting. Materials and Methods. We performed THA using DAA to 104 patients (114 hips) joints from August 2006 to April 2009 and identified for seventy five patients (eighty four hips) that imaging of the postoperative CT was possible. The orientation of acetabular sockets were performed using an alignment guide which assumed an operating table an axis from August 2006 to September 2008 (A group), and using an alignment guide which assumed a pelvis an axis from October 2008 to May 2009(B group). A group were thirty eight patients (forty four hips), and B group were twenty eight (thirty). There were two men and thirty six women in A group, and one man and twenty seven women in B group. The average age of both groups was 66 years old. The objective angle of the acetabular socket was performed as angle guide of abduction of 45° and anteversion of 20°. The orientation of the acetabular socket converted the angle of postoperative CT into radiographic angle, and measured it. For sixteen hips in B group, both angle guide was used, and there were measured a difference of two angle guide in the acetabular operation as movement of the pelvis. The examination item assumed it the mean values of angle for the acetabular socket in both groups, precision to set up the acetabular socket to planned orientation within ±5 °and a mean difference of two angle guides of sixteen hips in B group. Results. The mean values of abduction for the acetabular socket were 45 °in A group and 43.8 °in B group, and that of anteversion for the acetabular socket were 22.5 °in A group and were 20.9 °in B group. In A group, the precision to set up the acetabular socket to abduction 45±5 °was 91.8%, and that to anteversion 20±5 ° was 71%. Hips that anteversion of the acetabular socket was more than 25° were 13/44 joints. In B group, the precision to set up the acetabular socket to abduction of 45±5 °was 97%, and that to anteversion of 20±5°was 97.5%. The difference of two alignment guide for sixteen hips in B group were mean 5°(0～9°), and anteversion of pelvis decreased. Disccussion. THA using DAA causes a pelvic anteversion during the acetabular preparation and as a result, anteversion of postoperative acetabular sockets increase. It suggests that even if DAA is supine position, the movement of the pelvis occurs. Conclusion. The precision to set up the acetabular socket which we used alignment guide make the pelvis the axis was higher than that used alignment guide make the operating table the axis. In the acetabular preparation using DAA, anteversion of the pelvis occurred mean 5°

Aim. To test the hypothesis that surface skin swabs taken after skin preparation with alcoholic povidone iodine (APVPI) would not grow bacteria, whereas full thickness biopsies taken from the line of surgical incision would grow bacteria. Method. Informed consent was obtained from 44 patients undergoing primary hip (n=13) and knee (n=31) arthroplasty. Each received antimicrobial prophylaxis before skin preparation with APVPI under laminar flow. After the APVPI had dried, a skin swab and a full thickness 8mm x 4mm elliptical skin biopsy were taken from the line of incision. The skin swab was rolled in 5mL anaerobe basal broth to inactivate the APVPI, incubated at 37 degrees and checked for growth for 2 weeks. One half of the skin biopsy was snap frozen and used for gram and nitroblue tetrazolium staining. The other half was placed into 5mL of anaerobe basal broth, incubated at 37 degrees and monitored for growth for 2 weeks. Results. Forty-four skin biopsy samples and 42 corresponding swabs were collected. Fourteen of 42 surface swabs were positive for bacteria (5 Staphylococcus epidermidis, 6 Propionibacteria acnes, 1 S. aureus, 1 S. capitis, 1 S. epidermidis and P. acnes, and 1 S. warneri and P. acnes). Fifteen of 44 skin biopsies were positive for bacteria (7 P. acnes, 3 S. epidermidis, 1 S. aureus, 1 S. capitis, 1 Psuedomonas spp, 1 P. acnes and S. epidermidis, 1 S. edidermidis and S. capitis). Gram positive bacteria were seen in all gram stained sections of skin and all sections of skin were positive for live bacteria when stained with nitroblue tetrazolium. Discussion. This study shows that skin preparation with APVPI does not completely remove viable bacteria from the skin. Surgeons need to be aware of this and to adapt their surgical technique to avoid coming into contact with the patient's skin, including cut edges, when performing surgery involving implants

INTRODUCTION. Loosening is a major cause for revision in uncemented hip prostheses due to insufficient primary stability. Primary stability after surgery is achieved through press-fit in an undersized cavity. Cavity preparation is performed either by extraction (removing bone) or compaction (crushing bone) broaching. Densification of trabecular bone has been shown to enhance primary stability in human femora; however, the effect of clinically used compaction and extraction broaches on human bone with varying bone mineral density (BMD) has not yet been quantified. The purpose of this study was to determine the influence of the broach design and BMD on the level of densification at the bone-cavity interface, stem seating, the bone-implant contact area and the press-fit achieved. METHODS. Paired human femora (m/f=11/12, age=60±18 y) were scanned with quantitative computed tomography (QCT, Philips Brilliance 16) before broaching, with the final broach, after its removal and after stem implantation. Compaction broaching (n=4) was compared in an in situ (cadaver) study against extraction broaching with blunt tooth types (n=3); in an ex situ (excised femora) study, compaction broaching was compared against extraction broaching with sharp tooth types (n=8 each). QCT data were resampled to voxel sizes of 1×1×1 mm (in situ) and 0.5×0.5×1 mm (ex situ). Mean trabecular BMD of the proximal femur was determined. The cavity volumes were segmented in the post-broach images (threshold: −250 mgHA/cm3, Avizo 9.2) and a volume of interest (VOI) of one-voxel thickness was added around the cavity to capture the interfacial bone. VOIs were transferred to the pre-broach image and bone densification was calculated within each VOI as the increase from pre- to post-broach image (MATLAB). Detailed surface data sets of broaches and stems were collected with a 3D laser-scanner (Creaform Handyscan 700) and aligned with the segmented components in the CT scans (Fig. 1). Stem seating was defined as the difference between the top edge of the stem coating and the final broach. Distance maps between the stem and cavity surface were generated to determine the bone-implant contact area and press-fit. All parameters were analysed between 5 mm distal to the coating and 1 cm distal to the lesser trochanter and analysed with related-samples Wilcoxon signed rank and Spearman's correlation tests (IBM SPSS Statistics 22). RESULTS. Trabecular BMD ranged from 81 to 221 mgHA/cm3. Densification was higher with compaction compared to sharp (p=0.034), but not blunt extraction broaching (p=1.000). Proximal bone-implant contact area, press-fit and stem seating did not differ between broaching methods. Bone-implant contact area and bone densification increased with trabecular BMD (rs=0.658, p=0.001 and rs=0.443, p=0.034), press-fit with stem seating (rs=0.746, p<0.001) and contact area with bone densification (rs=0.432, p=0.039). DISCUSSION. Sharp extraction broaching reduces densification at the bone-cavity interface, but does not affect the press-fit or contact area. Trabecular BMD was positively associated with contact area, and stem seating with press-fit. Future studies will aim to link these findings to primary stability and influence on periprosthetic fractures. For any figures or tables, please contact authors directly

Introduction. Precision Freehand Sculpting(PFS), is a hand-held semi-active robotic technology for bone shaping that works within the surgical navigation framework. PFS can alternate between two control modes – one based on control of exposure of the cutting bur (“Exposure Control”) and another based on the control of the speed of the cutting bur (“Speed Control”). In this study we evaluate the performance of PFS in preparing the femoral bone surface for unicondylar knee replacement (UKR). Methods. The experiment is designed to prepare a synthetic bone for unicondylar knee replacement (UKR). The implant plan is mapped to individual specimen using a jig that fit in a unique and repeatable way to all specimens. During bone preparation, the PFS handpiece and the specimen are both tracked with the Polaris Spectra (Northern Digital Inc.) using passive reflective markers. The cutting plan is specified so that the specimens can receive a specially designed implant after the cut is finished. The implant is a modified commercial design with three planar back faces and two pegs. In addition there are 10 conical divots on the implant surface that can be used to register the implant after it is placed on the prepared bone surface. The distal and distal-anterior facets were cut with a 5 mm cylindrical bur using Extension Control. The posterior facet and the post holes were cut using 6 mm spherical bur using Speed Control. Three subjects cut 5 specimens each. One subject was an experienced PFS user. The second user was somewhat less experienced, and the third user was completely inexperienced with the use of PFS. The performance was evaluated in terms of the implant fit and the performance time. The final implant fit was characterized using a MicroScribe MX desktop coordinate measuring arm. Results. The average cut times for the first two cuts combined were 4:45 min, and for the posterior cut 3:26 min. The average distances/st.dev. from the planned implant position were 0.54 /0.23 mm and the angular differences were average/st.dev. of 1.08/ 0.53 degrees. Conclusions. All specimens were cut accurately, and with clinically acceptable surface finish. No implants were significantly malpositioned, nor were any unable to be positioned due to poor fit or planar malalignment. For both experienced users, the procedure times were short, averaging below 8 min, whereas the inexperienced user demonstrated rapid improvement in performance time

Introduction. Arthrodesis of the 1st metatarso-phalangeal joint (MTPJ) is a common procedure in forefoot surgery for hallux rigidus and severe hallux valgus. Debate persists on two issues - the best preparation method for the articular surfaces, and the optimal technique for operative stabilisation of the joint. Methods. We performed 1. st. MTPJ arthrodesis in 100 patients randomized into two equal groups. In the first group, the articular surfaces were prepared using cup-and-cone reamers, whilst in the second group, ‘flat cut’ osteotomies were performed with an oscillating saw. In all other respects, their treatment was identical. Fixation was secured using a plantar double compression Fixos™ screw and dorsal Anchorage™ plate. Full weight-bearing was allowed on the first post-operative day. Patients completed self-administered satisfaction questionnaires, including an AOFAS and SF-36 score pre-operatively and at two and six months post-operatively. Clinical examination and radiographs were compared at zero, two and six months. Statistical analysis was performed using Instat. Results. Radiographic union of the 1. st. MTPJ was documented in 45/50 patients in the reamer group and 42/50 in the ‘flat-cut’ group at two months and in all patients at six months. The AOFAS score improved from a mean of 46 +/− 15 pre-operatively to 72 +/−8 (out of 90) at two months and 83 +/− 4 (out of 90) at six months. SF-36 subscales for bodily pain and for physical function increased from 42.4 +/− 16.1 and 37.3 +/− 12.8 respectively pre-operatively to 82.2 +/− 11.2 and 84.6 +/− 9.3 respectively at six months. There was no statistically significant difference between groups. Conclusions. Arthrodesis of the 1. st. MTPJ with the Anchorage™ plate and compression screw gives excellent clinical and radiographic results. Preparation method does not affect early outcomes but may influence important technical points such as length of the first ray or inter-phalangeal angle

Introduction

To utilize existing cancellous bone for initial stability, custom-made stems were implanted without reaming and rasping. This study reviewed the results of this non-reaming technique.

A cleaning process reduces the contamination risk in bone impaction grafting but also modifies the grain size distribution. The cleaned allograft shows a higher mechanical stability than the untreated group.

In revision total hip replacement, bone loss can be managed by impacting porous bone chips. The bone chips have to be compacted to guarantee sufficient mechanical strength. To improve the safety of bone grafts and to reduce the risk of bacterial and viral contamination, cleaning processes are used to remove the organic portion of the tissue while maintaining its mechanical characteristics.

A cleaning procedure described by Coraca-Huber et al. was compared to untreated allografts by performing a sieve analysis, followed by an uniaxial compression test. Differences in grain size distribution and weight loss during the cleaning procedure were compared to data from literature. Yield stress limits, flowability coefficients as well as initial density and density at the yield limit of the two groups were determined for each group over 30 measurements. The measurements were taken before and after compression with an impaction apparatus (dropped weight).

The cleaning process reduced the initial weight by 56%, which is comparable to the results of McKenna et. al. Cleaned allograft showed a 25% lower weight of bone chips sized > 4 mm compared to data from a previous study.

The cleaned bone chips showed a statistically significant (p > 0.01) higher yield limit to a compression force (0.165 ± 0.069 MPa) compared to untreated allograft after compaction (0.117 ± 0.062 MPa). The flowability coefficient was 0.024 for the cleaned allograft and 0.034 for the untreated allograft.

Initial density as well as the density at the yield limit was higher for the untreated allografts, as the sample weight was twice as high as in the cleaned group, to compensate for the washout of the organic portion. The cleaned bone grafts showed a higher compaction rate, which was 31%, compared the the untreated group with a compaction rate of 22%.

The cleaned allograft showed a higher compaction rate, which means that the gaps between the single grains are filled out with smaller particles, resulting in better interlocking. In the untreated allograft the interlocking mechanism is hindered by the organic elements. This observation is confirmed by a reduced flowabillity and a higher yield stress limit. The loss of weight as well as a higher compaction rate implies that more cleaned graft material is needed to fill bone defects in hip surgery. Sonication may damage the bone structure of the allograft and reduce the size of the particles.

Source of the study: University of Auckland, Auckland, New Zealand. Unicompartmental knee arthroplasty (UKA) has benefits for patients with appropriate indications. However, UKA has a higher risk of revision, particularly for low-usage surgeons. The introduction of robotic-arm assisted systems may allow for improved outcomes but is also associated with a learning curve. We aimed to characterise the learning curve of a robotic-arm assisted system (MAKO) for UKA in terms of operative time, limb alignment, component sizing, and patient outcomes. Operative times, pre- and post-surgical limb alignments, and component sizing were prospectively recorded for consecutive cases of primary medial UKA between 2017 and 2021 (n=152, 5 surgeons). Patient outcomes were captured with the Oxford Knee Score (OKS), EuroQol-5D (EQ-5D), Forgotten Joint Score (FJS-12) and re-operation events up to two years post-UKA. A Cumulative Summation (CUSUM) method was used to estimate learning curves and to distinguish between learning and proficiency phases. Introduction of the system had a learning curve of 11 cases. There was increased operative time of 13 minutes between learning and proficiency phases (learning 98 mins vs. proficiency 85 mins; p<0.001), associated with navigation registration and bone preparation/cutting. A learning curve was also found with polyethylene insert sizing (p=0.03). No difference in patient outcomes between the two phases were detected for patient-reported outcome measures, implant survival (both phases 98%; NS) or re-operation (learning 100% vs. proficiency: 96%; NS). Implant survival and re-operation rates did not differ between low and high usage surgeons (cut-off of 12 UKAs per year). Introduction of the robotic-arm assisted system for UKA led to increased operative times for navigation registration and bone preparation, but no differences were detected in terms of component placement or patient outcomes regardless of usage. The short learning curve regardless of UKA usage indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons

Aim. The aim of this study was to develop an in-house multiplex PCR real-time assay on the LightCycler 480 system (Roche, Basel, Switzerland) with the aim of rapid detection of common pathogens in prosthetic joint infections (PJI), followed by validation on clinical samples (sonication fluid and tissue biopsies) routinely collected for PJI diagnosis. Methods. Using the PrimerQuest and CLC WorkBench tool, we designed six primer sets with specific fluorescently labelled TaqMan probes for the nuc gene in different Staphylococcus species (S. aureus, S. epidermidis, S. capitis, S. lugdunensis, S. hominis, S. haemolyticus). In addition, primers previously developed by Renz et al. (2022) for C. acnes were integrated into our assay with internal control of isolation, leading to the development of specific mPCR assay with seven included targets. Analytical sensitivity and specificity were evaluated using reference bacterial strains. To determine the assay's limit of detection (LOD), we conducted serial dilutions of eluates containing known concentrations of bacterial DNA copies/µl. The overall LOD in spiked clinical samples, including sample preparation and DNA isolation on MagnaPure24, was measured through 10-fold serial dilutions (from 10. 9. to 10. -1. CFU/ml) including additional dilutions of 5000, 500, 50 and 5 CFU/ml. Results. The results with LOD in serial dilutions of eluates and spiked clinical samples, together with analytical sensitivity and specificity, are shown in Table 1. Conclusion. The mPCR assay showed excellent analytical sensitivity and specificity, but with considerably lower LOD after sample preparation and further DNA isolation in spiked clinical samples. Although still promising in diagnostics of acute infections, the use of mPCR could be challenging in chronic, low-grade infections with lower microbial burden. Nevertheless, PCR offers significant advantages in terms of speed and can shorten the time to result, especially for C. acnes infections. Additionally, it represents a promising complementary approach in patients with suspected PJI on antibiotic therapy with negative culture results. For any tables or figures, please contact the authors directly

Aims. The microbiological detection of microorganisms plays a crucial role in the diagnosis as well as in the targeted systemic and local antibiotic therapy of periprosthetic infections (PJI). Despite extensive efforts to improve the sensitivity of current culture methods, the rate of culture-negative infections is approximately 10–20% of all PJI. This study investigates an preanalytical algorithm (culture collection and direct processing in the OR) to potentially increasing culture yield in patients with PJI. Methods. Patients undergoing staged revision arthroplasty for PJI in our hospital between October 2021 and 2022 were included in this prospective pilot study. Intraoperatively twenty tissue samples were collected and distributed among 4 groups. Tissue samples were prepared according to standard without medium and in thioglycolate medium at 3 different temperatures (room temperature, 4°C, 37° for 24h before transport to microbiology) directly in the OR. The removed implants were sonicated. Cultures were investigated on days 1, 3, 7, 12, 14 for possible growth. All grown organism, the number of positive samples and the time to positivity were recorded and compared. Results. 71 patients were included (age, gender). Compared to the standard procedure the thioglycolate broth at 37°C was significantly more often culture-negative (p=0.031). No significant differences in the frequency of culture-negative samples were detected in the other groups. 8.4% (6/71) patients were culture negative in the standard culture but positive in the thioglycolate samples. In contrast, 7% (5/71) were culture negative in the thioglycolate samples but had bacterial detection in the standard approach. In 4.7% (3/63) of the patients, only the sonication showed growth, whereas 25.4% (16/63) had no growth in sonication fluid but in one of the cultures. For S. caprae, there was a significantly different distribution (p=0.026) with more frequent detection in the group with thioglycolate at 37°C. The standard procedure (p=0.005) and sonication (p=0.023) showed a shorter time to positivity of the culture compared to the thioglycolate approach at 4°C. Conclusions. No general differences could be shown between the standard preparation and the thioglycolate preparation; in particular, storage at different temperatures does not seem to result in any difference. For individual cases (8% in this study), bacterial growth was detected in the thioglycolate group that would have been culture-negative otherwise. There might be organism dependent differences in growth in different media

Aim. The aim of this study is to evaluate if the gentamycin elution from bone cement is influenced by the timing of application of the antibiotic powder. Method. This was an experimental in vitro study that compared the elution properties of different formulation of gentamycin from a commercially available hip, knee and shoulder cement spacers. Four different experimental models were prepared. Five different spacers were prepared for each experimental mode and for each joint. We compared four different formulation of cement spacers: spacer #1, in which the spacer was prepared with a premixed bone-cement antibiotic mixture; spacer #2, in which the spacer was prepared by adding antibiotic powder to the bone cement at the time of spacer preparation; spacer #3, in which the spacer was prepared as spacer #2 but was stored for two months before starting the experiment; spacer #4, in addition to the gentamycin, other two antibiotics (tobramycin and vancomycin) were added to the bone cement. Gentamycin concentration was documented at seven intervals of time: T0 = 0h, T1 = 1h, T2 = 24h, T3 = 1W, T4 = 2W, T5 = 1M, T6 = 3M and T7 = 6M. The gentamycin elution at each interval of time was evaluated by using a T-student test. Results. Spacer #2, in which the gentamycin powder was added to the bone cement at the time of spacer preparation showed the higher gentamycin elution at each interval of time observed. In addition, Spacer #1, in which gentamycin powder was premixed with the bone cement showed a higher gentamycin elution when compared with spacer #3, in which the spacers were stored for two months to simulate the preformed spacers. Lastly, the addition of different antibiotic to the bone cement increases the gentamycin elution from the spacers (as demonstrated by spacer #4 model). Conclusions. a higher gentamycin elution was observed if spacer was prepared at the time of surgery when compared with preformed spacer. Lastly, our study confirmed the synergistic effect of adding one or more antibiotics with the aims to increase gentamycin elution

The Adams-Berger reconstruction is an effective technique for treating distal radioulnar joint (DRUJ) instability. Graft preparation techniques vary amongst surgeons with insufficient evidence to support one technique over another. Our study evaluated the biomechanical properties of four graft preparation techniques. Extensor tendons were harvested from fresh frozen porcine trotters obtained from a local butcher shop and prepared in one of three configurations (n=5 per group): tendon only; tendon prepared with non-locking, running suture (2-0 FiberLoop, Arthrex, Naples, FL) spaced at 6 mm intervals; and tendon prepared with suture spaced at 12 mm intervals. A fourth configuration of suture alone was also tested. Tendons were allocated in a manner to ensure comparable average diameters amongst groups. Biomechanical testing occurred using custom jigs simulating radial and ulnar tunnels attached to a Bose Electroforce 3510 mechanical testing machine (TA Instruments). After being woven through the jigs, all tendons were sutured end-to-end with 2-0 PROLENE suture (Ethicon). Tendons then underwent a staircase cyclic loading protocol (5-25 Newtons [N] at 1 hertz [Hz] for 1000 cycles, then 5-50 N at 1 Hz for 1000 cycles, then 5-75 N at 1 Hz for 1000 cycles) until graft failure; if samples did not fail during the protocol, they were then loaded to failure. Samples were visually inspected for mode of failure after the protocol. A one-way analysis of variance was used to compare average tendon diameter; post-hac Tuhey tests were used to compare elongation and elongation rate. Survival to cyclic loading was analyzed using Kaplan-Meier survival curves with log rank. Statistical significance was set at a = 0.05. The average tendon diameter of each group was not statistically different [4.17 mm (tendon only), 4.33 mm (FiberLoop spaced 6 mm), and 4.30 mm (FiberLoop spaced 12 mm)]. The average survival of tendon augmented with FiberLoop was significantly higher than tendon only, and all groups had significantly improved survival compared to suture only. There was no difference in survival between FiberLoop spaced 6 mm and 12 mm. Elongation was significantly lower with suture compared to tendon augmented with FiberLoop spaced 6 mm. Elongation rate was significantly lower with suture compared to all groups. Modes of failure included rupture of the tendon, suture, or both at the simulated bone and suture and/or tendon interface, and elongation of the entire construct without rupture. In this biomechanical study, augmentation of porcine tendons with FiberLoop suture spaced at either 6 or 12 mm for DRUJ reconstruction significantly increased survival to a staircase cyclic loading protocol, as suture material was significantly stiffer than any of the tendon graft configurations