Aims

Tissue adhesives (TAs) are a commonly used adjunct to traditional surgical wound closures. However, TAs must be allowed to dry before application of a surgical dressing, increasing operating time and reducing intraoperative efficiency. The goal of this study is to identify a practical method for decreasing the curing time for TAs.

Introduction. Offset femoral broach handles have become more common as the anterior approach in total hip arthroplasty has increased in popularity. The difference in access to the femur compared to a posterior approach necessitates anterior and, in some cases, lateral offsets incorporated into the design of the broach handle to avoid interference with the patient's body and to ensure accessibility of the strike plate. Using a straight broach handle with a primary stem, impaction force is typically directed along the axis of the femoral broach. However, the addition of one or more offsets to facilitate an anterior approach results in force transmission in the transverse plane, which is unnecessary for eating the femoral broach. The direction of forces transmitted to the broach via strike plate impaction can introduce a large moment. A negative consequence of this moment is the amplification of stresses/strains at the bone/broach interface, which increases the likelihood of femoral fracture during impaction. It was proposed that optimizing the angle of the strike plate could minimize the moment to reduce the unintended stresses/strains at the bone/broach interface. Objectives. The objective was to minimize the stresses/strains imparted to the proximal aspect of the bone femur when broaching with a given dual offset broach handle design. Methods. Trigonometric calculations were used to optimize the strike plate angle for a given dual offset broach handle design. The point of intersection of the stem axis and transverse plane that intersects the medial calcar of the smallest size broach was assumed to be the ideal location of zero moment, given that intraoperative fractures related to this issue tend to occur in the proximal region of the femur. The strike plate was angled anteriorly and laterally such that the impaction force vector is directed at this point of intersection, thus negating the moment at this point. A prototype broach handle body was fabricated to accept different strike plates. Of the two strike plates tested, one strike plate was made such that the impaction surface followed the optimized angle, while the other simulated the strike plate angle of a previous, non-optimized design. Each broach handle configuration was connected to an identical broach and implanted into one of two identical Sawbones® femoral models. Equal loads were placed on the strike plates of each handle perpendicular to the strike plate angles. Digital image correlation was used to compare the resultant strains in both samples. Results. Testing demonstrated a 30% reduction in maximum strain on the proximal aspect of the bone using the broach handle with the optimized strike plate. Conclusions. While the optimal strike plate angle is dependent on the individual broach handle design, this method of optimization can be applied to the design of any offset broach handle. Optimization of offset broach handle strike plate angles could reduce the incidence of intraoperative femoral fractures when broaching by reducing the stresses/strains on the proximal aspect of the femur

INTRODUCTION. Understanding the relationship between knee specific tissue behavior and joint contact mechanics remains an area of focus. Seminal work from 1990's established the possibility to optimize tissue properties for recreation of laxity driven kinematics (Mommersteeg et al., 1996). Yet, the uniqueness and validity of such predictions could be strengthened, especially as they relate to joint contact conditions. Understanding this interplay has implications for the long term performance of joint replacements. Development of instrumented knee implants, highlighted by a single use tibial insert trial with embedded sensor technology (VERASENSE, Orthosensor Inc.), may offer an avenue to establish the relationship between tissue state and joint mechanics. Utilization of related data also has the potential to confirm computational predictions, where both rigid body motions and associated reactions are explicitly accounted for. Hence, the goal of this work was to evaluate an approach for optimization of ligament properties using joint mechanics data from an instrumented implant during laxity style testing. Such a framework could be used to inform joint balancing techniques, improve long term implant performance, and alternatively, qualify factors that may lead to poor outcomes. METHODS. Experimentation was performed on a 52 year old male, left, cadaveric specimen. Joint arthroplasty was performed using standard practice by an experienced orthopedic surgeon. To mimic passive intraoperative loading, laxity loading at 10°, 45° and 90° flexion, which consisted of discrete application of anterior-posterior (± 100N), varus-valgus (± 5 Nm) and internal-external (± 3 Nm) loads at each angle, was performed using a simVITROTM robotic musculoskeletal simulator (Cleveland Clinic, Cleveland, OH). Experimental results included relative tibiofemoral kinematics and sensor measured metrics (Fig 1). The finite element model was developed from specimen-specific MRIs and solved using Abaqus/Explicit. The model included the rigid bones, appropriately placed implants and relevant soft-tissue structures (Fig. 1). Ligament stiffness values were adopted from the literature and included a 6% strain toe region. Sets of nonlinear springs, defined using MR imaging, comprised each ligament/bundle. Optimization was performed, which minimized the root mean squared difference between VERASENSE measured tibiofemoral mechanics and the model predicted values. Ligament slack lengths were the control variables and the objective included each loading state and all contact metrics (θ, AFD, ML, and LL). RESULTS AND DISCUSSION. The model successfully recreated joint kinematics with average errors of 4° for rotations and 3 mm for translations, across all flexion angles (Fig 2). Though a systematic offset in θ was observed, model versus experiment contact locations were also in good agreement. Reaction forces were generally over-predicted by the model, but retained the overall trend (Fig 2). Sensitivity analysis also supported this finding. In light of the larger focus of this project, testing also included systematic removal of key tissues followed by repeat testing, as evaluated across numerous specimens. Overall, the presented framework represents a promising step towards establishing simulation based tools able to support exploratory studies as well as the clinical decision making process. Future work will evaluate efficacy across numerous specimens and assess sensitivity to key modeling and experimental parameters. To view tables/figures, please contact authors directly

In the current healthcare environment, cost containment has become more important than ever. Perioperative services are often scrutinized as they consume more than 30% of North American hospitals’ budgets. The procurement, processing, and use of sterile surgical inventory is a major component of the perioperative care budget and has been recognized as an area of operational inefficiency. Although a recent systematic review supported the optimization of surgical inventory reprocessing as a means to increase efficiency and eliminate waste, there is a paucity of data on how to actually implement this change. A well-studied and established approach to implementing organizational change is Kotter's Change Model (KCM). The KCM process posits that organizational change can be facilitated by a dynamic 8-step approach and has been increasingly applied to the healthcare setting to facilitate the implementation of quality improvement (QI) interventions. We performed an inventory optimization (IO) to improve inventory and instrument reprocessing efficiency for the purpose of cost containment using the KCM framework. The purpose of this quality improvement (QI) project was to implement the IO using KCM, overcome organizational barriers to change, and measure key outcome metrics related to surgical inventory and corresponding clinician satisfaction. We hypothesized that the KCM would be an effective method of implementing the IO.

This study was conducted at a tertiary academic hospital across the four highest-volume surgical services - Orthopedics, Otolaryngology, General Surgery, and Gynecology. The IO was implemented using the steps outlined by KCM (Figure 1): 1) create coalition, 2) create vision for change, 3) establish urgency, 4) communicate the vision, 5) empower broad based action, 6) generate general short term wins, 7) consolidate gains, and 8) anchor change. This process was evaluated using inventory metrics - total inventory reduction and depreciation cost savings; operational efficiency metrics - reprocessing labor efficiency and case cancellation rate; and clinician satisfaction.

The implementation of KCM is described in Table 1. Total inventory was reduced by 37.7% with an average tray size reduction of 18.0%. This led to a total reprocessing time savings of 1333 hours per annum and labour cost savings of $39 995 per annum. Depreciation cost savings was $64 320 per annum. Case cancellation rate due to instrument-related errors decreased from 3.9% to 0.2%. The proportion of staff completely satisfied with the inventory was 1.7% pre-IO and 80% post-IO.

This was the first study to show the success of applying KCM to facilitate change in the perioperative setting with respect to surgical inventory. We have outlined the important organizational obstacles faced when making changes to surgical inventory. The same KCM protocol can be followed for optimization processes for disposable versus reusable surgical device purchasing or perioperative scheduling. Although increasing efforts are being dedicated to quality improvement and efficiency, institutions will need an organized and systematic approach such as the KCM to successfully enact changes.

For any figures or tables, please contact the authors directly.

Aim

The aim of the present work was (i) to survey the situation of healthcare regarding the use of antibiotics in orthopaedics and trauma surgery in Germany, (ii) to determine which empiric antibiotic regimens are preferred in the treatment of periprosthethic joint infections (PJI) and (iii) to evaluate the hypothetical antibiotic adequacy of the applied empirical antibiotic therapy regimens based on a patient collective of a German university hospital.

Neuromuscular scoliosis patients face rates of major complications of up to 49%. Along with pre-operative risk reduction strategies (including nutritional and bone health optimization), intra-operative strategies to decrease blood loss and decrease surgical time may help mitigate these risks. A major contributor to blood loss and surgical time is the insertion of instrumentation which is challenging in neuromuscular patient given their abnormal vertebral and pelvic anatomy. Standard pre-operative radiographs provide minimal information regarding pedicle diameter, length, blocks to pedicle entry (e.g. iliac crest overhang), or iliac crest orientation. To minimize blood loss and surgical time, we developed an “ultra-low dose” CT protocol without sedation for neuromuscular patients.

Our prospective quality improvement study aimed to determine: if ultra-low dose CT without sedation was feasible given the movement disorders in this population; what the radiation exposure was compared to standard pre-operative imaging; whether the images allowed accurate assessment of the anatomy and intra-operative navigation given the ultra-low dose and potential movement during the scan.

Fifteen non-ambulatory surgical patients with neuromuscular scoliosis received the standard spine XR and an ultra-low dose CT scan. Charts were reviewed for etiology of neuromuscular scoliosis and medical co-morbidities. The CT protocol was a high-speed, high-pitch, tube-current modulated acquisition at a fixed tube voltage. Adaptive statistical iterative reconstruction was applied to soft-tissue and bone kernels to mitigate noise. Radiation dose was quantified using reported dose indices (computed tomography dose index (CTDIvol) and dose-length product (DLP)) and effective dose (E), calculated through Monte-Carlo simulation. Statistical analysis was completed using a paired student's T-test (α = 0.05). CT image quality was assessed for its use in preoperative planning and intraoperative navigation using 7D Surgical System Spine Module (7D Surgical, Toronto, Canada).

Eight males and seven females were included in the study. Their average age (14±2 years old), preoperative Cobb angle (95±21 degrees), and kyphosis (60±18 degrees) were recorded. One patient was unable to undergo the ultra-low dose CT protocol without sedation due to a co-diagnosis of severe autism. The average XR radiation dose was 0.5±0.3 mSv. Variability in radiographic dose was due to a wide range in patient size, positioning (supine, sitting), number of views, imaging technique and body habitus. Associated CT radiation metrics were CTDIvol = 0.46±0.14 mGy, DLP = 26.2±8.1 mGy.cm and E = 0.6±0.2 mSv. CT radiation variability was due to body habitus and arm orientation. The radiation dose differences between radiographic and CT imaging were not statistically significant. All CT scans had adequate quality for preoperative assessment of pedicle diameter and orientation, obstacles impeding pedicle entry, S2-Alar screw orientation, and intra-operative navigation.

“Ultra-low dose” CT scans without sedation were feasible in paediatric patients with neuromuscular scoliosis. The effective dose was similar between the standard preoperative spinal XR and “ultra-low dose” CT scans. The “ultra-low dose” CT scan allowed accurate assessment of the anatomy, aided in pre-operative planning, and allowed intra-operative navigation despite the movement disorders in this patient population.

Neuromuscular scoliosis patients face rates of major complications of up to 49%. Along with pre-operative risk reduction strategies (including nutritional and bone health optimization), intra-operative strategies to decrease blood loss and decrease surgical time may help mitigate these risks. A major contributor to blood loss and surgical time is the insertion of instrumentation which is challenging in neuromuscular patient given their abnormal vertebral and pelvic anatomy. Standard pre-operative radiographs provide minimal information regarding pedicle diameter, length, blocks to pedicle entry (e.g. iliac crest overhang), or iliac crest orientation. To minimize blood loss and surgical time, we developed an “ultra-low dose” CT protocol without sedation for neuromuscular patients.

Our prospective quality improvement study aimed to determine:

Fifteen non-ambulatory surgical patients with neuromuscular scoliosis received the standard spine XR and an ultra-low dose CT scan. Charts were reviewed for etiology of neuromuscular scoliosis and medical co-morbidities. The CT protocol was a high-speed, high-pitch, tube-current modulated acquisition at a fixed tube voltage. Adaptive statistical iterative reconstruction was applied to soft-tissue and bone kernels to mitigate noise. Radiation dose was quantified using reported dose indices (computed tomography dose index (CTDIvol) and dose-length product (DLP)) and effective dose (E), calculated through Monte-Carlo simulation. Statistical analysis was completed using a paired student's T-test (α= 0.05). CT image quality was assessed for its use in preoperative planning and intraoperative navigation using 7D Surgical System Spine Module (7D Surgical, Toronto, Canada).

Eight males and seven females were included in the study. Their average age (14±2 years old), preoperative Cobb angle (95±21 degrees), and kyphosis (60±18 degrees) were recorded. One patient was unable to undergo the ultra-low dose CT protocol without sedation due to a co-diagnosis of severe autism. The average XR radiation dose was 0.5±0.3 mSv. Variability in radiographic dose was due to a wide range in patient size, positioning (supine, sitting), number of views, imaging technique and body habitus. Associated CT radiation metrics were CTDIvol = 0.46±0.14 mGy, DLP = 26.2±8.1 mGy.cm and E = 0.6±0.2 mSv. CT radiation variability was due to body habitus and arm orientation. The radiation dose differences between radiographic and CT imaging were not statistically significant. All CT scans had adequate quality for preoperative assessment of pedicle diameter and orientation, obstacles impeding pedicle entry, S2-Alar screw orientation, and intra-operative navigation.

“Ultra-low dose” CT scans without sedation were feasible in paediatric patients with neuromuscular scoliosis. The effective dose was similar between the standard preoperative spinal XR and “ultra-low dose” CT scans. The “ultra-low dose” CT scan allowed accurate assessment of the anatomy, aided in pre-operative planning, and allowed intra-operative navigation despite the movement disorders in this patient population.

Many navigation (Image Guided Surgery or IGS) systems are keyed to safely and accurately placing implants into complex anatomy. In spine surgery such as disc arthroplasty and fusion surgery this can be extremely helpful. Likewise, in joint arthroplasty the accurate placement with respect to the operative plan is widely recognized to be of benefit to long term results.

However, where realignment of anatomy is desired following implant placement, such as in high tibial osteotomy, spinal fusion with correction of deformity, and spinal disc arthroplasty, navigation systems can tell you where you are, but not where you would like to be.

We have developed specific software modification technology, applicable to all current navigation systems that addresses this need for assistance in surgical correction of anatomy to a desired alignment without the requirement for further imaging or irradiation. The benefits of our software allow image free re-referencing of image guided surgery, accommodation of intra-operative changes in anatomy, and intra-operative accountability and adjustment to allow errors of image guidance to be identifiable and correctible, at any stage of image guided surgery.

This software allows accurate pre-operative planning, intra-operative verification and assessment of the operative plan, and actual outcomes of the surgery to be assessed as the surgery is performed. It allows the surgeon to subsequently verify if the operative planning has been adequately achieved, and if not can verify if continued surgery has then achieved the planning goals. This verification and image guidance does not require further imaging during surgery, relying upon the original data set and software enhancements.

INTRODUCTION

There is great potential for the use of computational tools within the design and test cycle for joint replacement devices.

The increasing need for stratified treatments that are more relevant to specific patients, and implant testing under more realistic, less idealised, conditions, will progressively increase the pre-clinical experimental testing work load. If the outcomes of experimental tests can be predicted using low cost computational tools, then these tools can be embedded early in the design cycle, e.g. benchmarking various design concepts, optimising component geometrical features and virtually predicting factors affecting the implant performance. Rapid, predictive tools could also allow population-stratified scenario testing at an early design stage, resulting in devices which are better suited to a patient-specific approach to treatment.

The aim of the current study was to demonstrate the ability of a rapid computational analysis tool to predict the behaviour of a total hip replacement (THR) device, specifically the risk of edge loading due to separation under experimental conditions.

Introduction

Spatial orientation of the pelvis in the sagittal plane is a key parameter for hip function. Pelvic extension (or retroversion) and pelvic flexion(or anteversion) are currently assessed using Sacral Slope (SS) evaluation (respectively SS decrease and SS increase). Pelvic retroversion may be a risk situation for THA patients. But the magnitude of SS is dependant on the magnitude of pelvic incidence (PI) and may fail to discriminate pelvic position due to patient's anatomy and the potential adaptation mechanisms: a high PI patient has a higher SS but this situation can hide an associated pelvic extension due to compensatory mechanisms of the pelvic area. A low PI patient has a lower SS with less adaptation possibilities in case of THA especially in aging patients. The individual relative pelvic version (RPV) is defined as the difference between « measured SS » (SSm) minus the « normal SS »(SSn) described for the standard population. The aim of the study was to evaluate RPV in standing and sitting position with a special interest for high and low PI patients.

The success of a cementless Total Hip Arthroplasty (THA) depends not only on initial micromotion, but also on long-term failure mechanisms, e.g., implant-bone interface stresses and stress shielding. Any preclinical investigation aimed at designing femoral implant needs to account for temporal evolution of interfacial condition, while dealing with these failure mechanisms. The goal of the present multi-criteria optimization study was to search for optimum implant geometry by implementing a novel machine learning framework comprised of a neural network (NN), genetic algorithm (GA) and finite element (FE) analysis. The optimum implant model was subsequently evaluated based on evolutionary interface conditions.

The optimization scheme of our earlier study [1] has been used here with an additional inclusion of an NN to predict the initial fixation of an implant model. The entire CAD based parameterization technique for the implant was described previously [1]. Three objective functions, the first two based on proximal resorbed Bone Mass Fraction (BMF) [1] and implant-bone interface failure index [1], respectively, and the other based on initial micromotion, were formulated to model the multi-criteria optimization problem. The first two objective functions, e.g., objectives f1 and f2, were calculated from the FE analysis (Ansys), whereas the third objective (f3) involved an NN developed for the purpose of predicting the post-operative micromotion based on the stem design parameters. Bonded interfacial condition was used to account for the effects of stress shielding and interface stresses, whereas a set of contact models were used to develop the NN for faster prediction of post-operative micromotion. A multi-criteria GA was executed up to a desired number of generations for optimization (Fig. 1). The final trade-off model was further evaluated using a combined remodelling and bone ingrowth simulation based on an evolutionary interface condition [2], and subsequently compared with a generic TriLock implant.

The non-dominated solutions obtained from the GA execution were interpolated to determine the 3D nature of the Pareto-optimal surface (Fig. 2). The effects of all failure mechanisms were found to be minimized in these optimized solutions (Fig. 2). However, the most compromised solution, i.e., the trade-off stem geometry (TSG), was chosen for further assessment based on evolutionary interfacial condition. The simulation-based combined remodelling and bone ingrowth study predicted a faster ingrowth for TSG as compared to the generic design. The surface area with post-operative (i.e., iteration 1) ingrowth was found to be ∼50% for the TSG, while that for the TriLock model was ∼38% (Fig. 3). However, both designs predicted similar long-term ingrowth (∼89% surface area). The long-term proximal bone resorption (upto lesser trochanter) was found to be ∼30% for the TSG, as compared to ∼37% for the TriLock model. The TSG was found to be bone-preserving with prominent frontal wedge and rectangular proximal section for better rotational stability; features present in some recent designs. The optimization scheme, therefore, appears to be a quick and robust preclinical assessment tool for cementless femoral implant design.

To view tables/figures, please contact authors directly.

Aims. Orthopaedic infection is a potentially serious complication of elective and emergency trauma and orthopaedic procedures, with a high associated burden of morbidity and cost. Optimization of vitamin D levels has been postulated to be beneficial in the prevention of orthopaedic infection. This study explores the role of vitamin D in orthopaedic infection through a systematic review of available evidence. Methods. A comprehensive search was conducted on databases including Medline and Embase, as well as grey literature such as Google Scholar and The World Health Organization Database. Pooled analysis with weighted means was undertaken. Results. Pooled analysis of four studies including 651 patients found the mean 25(OH)D level to be 50.7 nmol/l with a mean incidence of infection of 70%. There was a paucity of literature exploring prophylactic 25(OH)D supplementation on reducing orthopaedic infection, however, there was evidence of association between low 25(OH)D levels and increased incidence of orthopaedic infection. Conclusion. The results indicate a significant proportion of orthopaedic patients have low 25(OH]D levels, as well as an association between low 25(OH)D levels and orthopaedic infection, but more randomized controlled trials need to be conducted to establish the benefit of prophylactic supplementation and the optimum regimen by dose and time. Cite this article: Bone Jt Open 2021;2(9):721–727

Cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sexes and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially for Anterior and MIS exposures; Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimization of proximal femoral load transfer with consequent maximization of proximal bone preservation. The purpose of this presentation is to describe the design rationale and characteristics of short (< 120 mm) uncemented primary THA femoral stems and to evaluate the clinical and radiographic results of short stems. Outcome results extending beyond 10 years support the proposition that short stems of appropriate design provide dependable long-term fixation and equivalent clinical results to those currently achievable with cementless stems of conventional length in patients of all ages, sexes and level of activity

As an increasing number of young, active, large patients are becoming candidates for total hip replacements, there is an increasingly urgent need to identify arthroplasties that will be durable, highly functional and amenable to possible future successful revision. In an era when cemented femoral stems were the primary implant option, the concept of a surface replacement was attractive and, perhaps, appropriate. However, cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sex and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially with MIS THA exposures; Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimization of proximal femoral load transfer with consequent maximization of proximal bone preservation. The purpose of this presentation is to describe the design rationale and characteristics of short (< 115 mm) uncemented primary THA femoral stem, to evaluate the clinical and radiographic results of short stems and to discuss the possible drawbacks specific to the use of short stems

As an increasing number of young, active, large patients are becoming candidates for total hip replacements, there is an increasingly urgent need to identify arthroplasties that will be durable, highly functional and amenable to possible future successful revision. In an era when cemented femoral stems were the primary implant option, the concept of a surface replacement was attractive and, perhaps, appropriate. However, cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sex and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially with MIS THA exposures; Facilitation of revision with implants capable of providing durable fixation for active patients. The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimization of proximal femoral load transfer with consequent maximization of proximal bone preservation. The purpose of this presentation is to describe the design rationale and characteristics of short (<115mm) uncemented primary THA femoral stem, to evaluate the clinical and radiographic results of short stems and to discuss the possible drawbacks specific to the use of short stems

Cellular therapies play an important role in tendon tissue engineering with tenocytes being described as the most prominent cell population if available in large numbers. However, in vitro expansion of tenocytes in standard culture leads to phenotypic drift and cellular senescence. Recent work suggests that maintenance of tenogenic phenotype in vitro can be achieved by recapitulating different aspects of the native tendon microenvironment. One approach used to modulate the in vitro microenvironment and enhance extracellular matrix (ECM) deposition is macromolecular crowding (MMC). MMC is based on the addition of inert macromolecules to the culture media mimicking the dense extracellular matrix. In addition, as tendon has been described to be a relatively avascular and hypoxic tissue and low oxygen tension can stimulate collagen synthesis and cross-linking, we venture to assess the synergistic effect of MMC and low oxygen tension on human tenocyte phenotype maintenance by enhancing synthesis and deposition of tissue-specific ECM. Human tendons were kindly provided from University Hospital Galway, after obtaining appropriate licenses, ethical approvals and patient consent. Afterwards, tenocytes were extracted using the migration method. Experiments were conducted at passage three. Optimization of MMC conditions was assessed using 50 to 500 μg/ml carrageenan (Sigma Aldrich, UK). For variable oxygen tension cultures, tenocytes were incubated in a Coy Lab (USA) hypoxia chamber. ECM synthesis and deposition were assessed using SDS-PAGE (BioRad, UK) and immunocytochemistry (ABCAM, UK) analysis. Protein analysis for Scleraxis (ABCAM, UK) was performed using western blot. Gene analysis was conducted using a gene array (Roche, Ireland). Cell morphology was assessed using bright-field microscopy. All experiments were performed at least in triplicate. MINITAB (version 16, Minitab, Inc.) was used for statistical analysis. Two-sample t-test for pairwise comparisons and ANOVA for multiple comparisons were conducted. SDS-PAGE and immunocytochemistry analysis demonstrated that human tenocytes treated with the optimal MMC concentration at 2% oxygen tension showed increased synthesis and deposition of collagen type I, the major component of tendon ECM. Moreover, immunocytochemistry for the tendon-specific ECM proteins collagen type III, V, VI and fibronectin illustrated enhanced deposition when cells were treated with MMC at 2% oxygen tension. In addition, protein analysis revealed elevated dexpression of the tendon-specific protein Sclearaxis, while a detailed gene analysis revealed upregulation of tendon-related genes and downregulation of trans-differentiation markers again when cells cultured with MMC at 2% oxygen tension. Finally, low oxygen tension and MMC did not affect the metabolic activity, proliferation and viability of human tenocytes. Collectively, results suggest that the synergistic effect of MMC and low oxygen tension can accelerate the formation of ECM-rich substitutes, which stimulates tenogenic phenotype maintenance. Currently, the addition of substrate aligned topography together with MMC and hypoxia is being investigated in this multifactorial study for the development of an implantable device for tendon regeneration

Introduction. With many stakeholders, healthcare decisions are complex. However, patient interests should be prioritized. This maximizes healthcare value (quality divided by cost), simultaneously minimizing costs (objective) and maximizing quality (subjective). Unfortunately, even ‘high value’ procedures like total knee arthroplasty (TKA) suffer from recovery assessment subjectivity (i.e. high assessment variability) and increasing costs. High TKA costs and utilization yield high annual expenditures (∼$22B), including postoperative physical therapy (PT) accounting for ∼10% of total costs (∼$2.3B annually). Post-TKA PT is typically homogenous across subjects ensuring most recover, however recent work shows outcomes unimpacted by PT. Accordingly, opportunities exist improving healthcare value by simultaneously reducing unnecessary PT expenditures and improving outcomes. However, discerning recovery completion relies on discrete ROM measures captured clinically and subjective clinician experience (i.e. intuition about recovery). Accordingly, our goal was developing objective post-TKA performance assessment methods utilizing gait knee ROM and statistical analyses to categorize patient recovery (‘accelerated,’ ‘delayed,’ or ‘normal’). Methods. We first established statistical reasons for current post-TKA rehabilitation including risk-reward tradeoffs between incorrectly ascribing ‘poor recovery’ to well-recovering patients (T1 error) or ‘good recovery’ to poorly-recovering patients (T2 error) using methods described by Mudge et al. and known TKA volumes/rehabilitation costs. Next, previously captured gait ROM data from well-healed patients was utilized establishing standard recovery curves. These were then utilized to assess newly captured patient recovery. Following IRB approval, we prospectively captured gait ROM from 10 TKA patients (3M, 69±13 years) 1-week pre-TKA and 6-weeks immediately post-TKA. Performance was compared to recovery curves via control charts/Shewhart rules (daily performance) as well as standard deviation thresholds (weekly performance) establishing recovery as ‘accelerated,’ ‘delayed,’ or ‘normal.’ The categorization was extrapolated to US TKA population and savings/expenses quantified. Statistical analyses were performed in Minitab with statistical significance set to α<0.05. Results. Current post-TKA approach is as much PT as possible (AMPTAP). AMPTAP was confirmed statistically. Because poor recovery costs are significant, balancing T1/T2 error minimizes risk by removing T1 error risk (α=0.00) via 27 PT sessions for equal cost to one manipulation under anaesthesia (MUA). Previously captured, well-healed subject gait ROM were always normally distributed. Assessing performance via control charts showed serial ‘accelerated’/‘delayed’ recovery and would serially under/over-prescribe PT. Establishing recovery performance via ±1SD thresholds successfully evaluated 3 clinically established “poor recoverers” as ‘delayed’ and the reaming clinically established “good recoverers” as ‘normal’ or ‘accelerated’ throughout recovery. Discussion. Optimization for current AMPTAP approach, while effective reducing poor recovery risk, is a gross misuse of rehabilitation spending. Improved methods are necessary including those rooted with strong statistical foundation. Control charts are likely too fine an assessment as patient performance day-to-day is too variable resulting in clinical rehabilitation prescription over-reactions. In contrast, standard deviation thresholds likely provide a conservative approach that allows clinicians the opportunity to improve postoperative rehabilitation week-after-week throughout recovery. However, PT was not altered herein. Thus, the impact altering PT has on postoperative outcomes remains unknown. Future work should investigate how altering postoperative rehabilitation changes postoperative outcomes. For any figures or tables, please contact authors directly

Musculoskeletal modeling techniques simulate reverse total shoulder arthroplasty (RTSA) shoulders and how implant placement affects muscle moment arms. Yet, studies have not taken into account how muscle-length changes affect force-generating capacity postoperatively. We develop a patient-specific model for RTSA patients to predict muscle activation. Patient-specific muscle parameters were estimated using an optimization scheme calibrating the model to isometric arm abduction data at 0°, 45°, and 90°. We compared predicted muscle activation to experimental electromyography recordings. A twelve-degree of freedom model with experimental measurements created patient-specific data estimating muscle parameters corresponding to strength. Optimization minimized the difference between measured and estimated joint moments and muscle activations, yielding parameters corresponding to subjects' strength that can predict muscle activation and lengths. Model calibration was performed on RTSA patients' arm abduction data. Predicted muscle activation ranged between 3% and 70% of maximum. The maximum joint moment produced was 10 Nm. The model replicated measured moments accurately (R. 2. > 0.99). The optimized muscle parameters produced feasible muscle moments and activations for dynamic arm abduction when using data from isometric force trials. A normalized correlation was found between predicted and experimental muscle activation for dynamic abduction (r > 0.9); the moment generation to lift the arm was tracked (R. 2. = 0.99). Statement of Clinical Significance: We developed a framework to predict patient-specific muscle parameters. Combined with patient-specific models incorporating joint configurations, kinematics, and bone anatomy, they can predict muscle activation in novel tasks and, e.g., predict how RTSA implant and surgical decisions may affect muscle function

Revision total knee arthroplasty (TKA) can pose significant challenges. Successful reconstruction requires a systematic approach with the ultimate goal being a well fixed and balanced knee prosthesis. Careful preoperative planning is necessary for safe exposure, component removal, and appropriate management of bone loss during revision knee surgery. Prior to surgery, the cause of failure must be understood. Revision TKA without a clear diagnosis has been shown to lead to predictable poor results. A careful history and physical examination for both intrinsic and extrinsic causes of knee pain need to be performed. An ESR and C-reactive protein should be obtained in every patient with a painful TKA and in cases of serologic abnormalities, a joint aspiration performed. The integrity of the collateral ligaments and the degree of anticipated bone loss at the time of revision needs to be established. In cases of severe collateral ligament deficiency, the need for constrained or hinged knee implants should be anticipated. Plain radiographs are needed to evaluate present component position, loosening, and osteolysis. Oblique radiographs and advanced imaging (i.e. CT or MRI) have been shown to more accurately quantify the severity of lysis compared to standard radiographs. This careful assessment can help prepare for the need of special implants, stems, wedges, or augments. Finally, patient risk stratification and medical co-management can help minimise complications following revision TKA. Optimization of potentially modifiable risk factors such as glycemic control, BMI, and preoperative hemoglobin can reduce perioperative morbidity and complications

The number one reason to consider large heads in total hip arthroplasty (THA) is for increased stability. Large diameter femoral heads substantially increase stability by virtue of increased range of motion and increased jump distance, which is the amount of displacement required to sublux the head out of the socket. Prevention is the best means for reducing dislocation, with requisites for stability being appropriate component position, restoration of leg length, and restoration of offset. In a review from our center studying the frequency of dislocation with small diameter femoral heads (≤32 mm) in 1262 patients (1518 hips) who underwent primary THA performed via a direct lateral approach, we observed a dislocation rate of 0.8% (12 of 1518). In a subsequent study of 1748 patients (2020 hips) who underwent primary THA at our center with large diameter heads (mean 43 mm, range 36–60 mm), we observed a substantially lower 0.04% frequency of dislocation (one of 2010) at a mean followup of 2.6 years. Our findings have been echoed in studies from several other centers. Howie et al. reported a prospective controlled trial of 644 low risk patients undergoing primary or revision THA randomised to receive either a 36 mm or 28 mm metal head articulated on highly crosslinked polyethylene. They observed significantly lower frequency of frequency of dislocation with 36 mm heads both overall (1.3%, 4 of 299 versus 5.4%, 17 of 216 with 28 mm heads, p=0.012) and in primary use (0.8%, 2 of 258 versus 4.4%, 12 of 275 with 28 mm heads, p=0.024), and a similar trend in their smaller groups of revision patients (5%, 2 of 41, versus 12%, 5 of 41 with 28 mm heads, p=0.273). Lachiewicz and Soileau reported on early and late dislocation with 36- and 40 mm heads in 112 patients (122 hips) at presumed high risk for dislocation who underwent primary THA. Risk factors were age >75 for 80 hips, proximal femur fracture for 18, history of contralateral dislocation for 2, history of alcohol abuse in 2, large acetabulum (>60 mm) in 6, and other reasons in 14. Early dislocation (<1 year) occurred in 4% (5 of 122), all with 36 mm heads. Late dislocation (>5 years) did not occur in any of the 74 patients with followup beyond 5 years. Stroh et al. compared 225 patients (248 hips) treated with THA using small diameter heads (<36 mm) to 501 patients (559 hips) treated with THA using large diameter heads (≥36 mm). There were no dislocations with large diameter heads compared with 1.8% (10 of 559) with small diameter heads. Allen et al. studied whether or not large femoral heads improve functional outcome after primary THA via the posterior approach in 726 patients. There were 399 done with small heads (<36 mm), 254 with medium heads (36 mm), and 73 with large heads (>36 mm), analyzed pre-operatively, at 6 months, and at 12 months. The authors could not find a correlation between increasing head size and improved function at one year, but observed that dislocation was reduced with large diameter heads. Optimization of hip biomechanics via proper surgical technique, component position, and restoration of leg length and offset are mandatory in total hip arthroplasty. Large heads enhance stability by increasing range of motion prior to impingement and enhancing jump stability