Stiffness is reported in up to 16% of patients after total knee replacement (TKR)1. Treatment of stiffness after TKR remains a challenge. Manipulation under anaesthesia (MUA) accounts for between 6%-36% of readmissions following TKR2,3. The outcomes of MUA remain variable/unpredictable. Post-operative CPM is used as an adjuvant to MUA, potentially offering improved ROM, however, remains the subject of debate. We report a retrospective study comparing MUA with and without post-operative CPM. In our institution patients undergoing MUA to receive CPM post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period MUA procedures were undertaken without CPM. Two cohorts were included: 1) MUA + post-operative CPM 2) Daycase MUA. Patients’ demographics, pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded. Between 2017-2022 126 patients underwent MUA and were admitted for CPM and 42 had daycase MUA. The median Age was 66.5 and 64% were female. 57% had extension deficit (>5o), 70% had flexion deficit (< 90o), and 37% had both. The mean Pre-operative ROM was 72.3o(SD:18.3o) vs. 68.5o(19.0o), ROM at MUA was 95.5o(SD:20.7o) vs 108.3o(SD:14.1o) [p< 0.01], and at final follow-up 87.4o(SD:21.9o) vs. 92.1o(SD:18.2o) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92%(SD:17) and 85%(SD:14)[p=0.03] for daycase and CPM groups respectively. There was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. The CPM group lost a greater ROM after MUA (15% vs. 8%). We conclude that post-operative CPM does not improve ROM achieved after MUA.
The primary aim of this study was to present the mid-term follow-up of a multicentre randomized controlled trial (RCT) which compared the functional outcome following routine removal (RR) to the outcome following on-demand removal (ODR) of the syndesmotic screw (SS). All patients included in the ‘ROutine vs on DEmand removal Of the syndesmotic screw’ (RODEO) trial received the Olerud-Molander Ankle Score (OMAS), American Orthopaedic Foot and Ankle Hindfoot Score (AOFAS), Foot and Ankle Outcome Score (FAOS), and EuroQol five-dimension questionnaire (EQ-5D). Out of the 152 patients, 109 (71.7%) completed the mid-term follow-up questionnaire and were included in this study (53 treated with RR and 56 with ODR). Median follow-up was 50 months (interquartile range 43.0 to 56.0) since the initial surgical treatment of the acute syndesmotic injury. The primary outcome of this study consisted of the OMAS scores of the two groups.Aims
Methods
Stiffness is reported in 4%–16% of patients after having undergone total knee replacement (TKR). Limitation to range of motion (ROM) can limit a patient's ability to undertake activities of daily living with a knee flexion of 83o, 93o, and 106o required to walk up stairs, sit on a chair, and tie one's shoelaces respectively. The treatment of stiffness after TKR remains a challenge. Many treatment options are described for treating the stiff TKR. In addition to physiotherapy the most employed of these is manipulation under anaesthesia (MUA). MUA accounts for up to 36% of readmissions following TKR. Though frequently undertaken the outcomes of MUA remain variable and unpredictable. CPM as an adjuvant therapy to MUA remains the subject of debate. Combining the use of CPM after MUA in theory adds the potential benefits of CPM to those of MUA potentially offering greater improvements in ROM. This paper reports a retrospective study comparing patients who underwent MUA with and without post-operative CPM. Standard practice in our institution is for patients undergoing MUA for stiff TKR to receive CPM for between 12–24hours post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period several MUA procedures were undertaken without subsequent inpatient CPM. We retrospectively identified two cohorts of patients treated for stiff TKR: group 1) MUA + post-operative CPM 2) Daycase MUA. All patients had undergone initial physiotherapy to try and improve their ROM prior to proceeding to MUA. In addition to patients’ demographics pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded for each patient.Abstract
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Obesity is prevalent with nearly one third of the world's population being classified as obese. Total knee arthroplasty (TKA) is an effective treatment option for high BMI patients achieving similar outcomes to non-obese patients. However, increased rates of aseptic loosening in patients with a high BMI have been reported. In patients with high BMI/body mass there is an increase in strain placed on the implant fixation interfaces. As such component fixation is a potential concern when performing TKA in the obese patient. To address this concern the use of extended tibial stems in cemented implants or cementless fixation have been advocated. Extend tibial stems are thought to improve implant stability reducing the micromotion between interfaces and consequently the risk of aseptic loosening. Cementless implants, once biologic fixation is achieved, effectively integrate into bone eliminating an interface. This retrospective study compared the use of extended tibial stems and cementless implants to conventional cemented implants in high BMI patients. From a prospectively maintained database of 3239 primary Attune TKA (Depuy, Warsaw, Indiana), obese patients (body mass index (BMI) >30 kg/m²) were retrospectively reviewed. Two groups of patients 1) using a tibial stem extension [n=162] and 2) cementless fixation [n=163] were compared to 3) a control group (n=1426) with a standard tibial stem cemented implant. All operations were performed by or under the direct supervision of specialist arthroplasty surgeons. Analysis compared the groups with respect to class I, II, and III (BMI >30kg/m², >35 kg/m², >40 kg/m²) obesity. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Where radiographic images at greater than 3 months post-operatively were available, radiographs were examined to compare the presence of peri-implant radiolucent lines.Abstract
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Up to 20% of patients can remain dissatisfied following TKR. A proportion of TKRs will need early revision with aseptic loosening the most common. The ATTUNE TKR was introduced in 2011 as successor to its predicate design The PFC Sigma (DePuy Synthes, Warsaw, In). However, following reports of early failures of the tibial component there have been ongoing concerns of increased loosening rates with the ATTUNE TKR. In 2017 a redesigned tibial baseplate (S+) was introduced, which included cement pockets and an increased surface roughness to improve cement bonding. Given the concerns of early tibial loosening with the ATTUNE knee system, this study aimed to compare revision rates and those specific to aseptic loosening of the ATTUNE implant in comparison to an established predicate as well as other implant designs used in a high-volume arthroplasty centre. The Attune TKR was introduced to our unit in December 2011. Prior to this we routinely used a predicate design with an excellent long-term track record (PFC Sigma) which remains in use. In addition, other designs were available and used as per surgeon preference. Using a prospectively maintained database, we identified 10,202 patients who underwent primary cemented TKR at our institution between 01/04/2003–31/03/2022 with a minimum of 1 year follow-up (Mean 8.4years, range 1–20years): 1) 2406 with ATTUNE TKR (of which 557 were S+) 2) 4652 with PFC TKR 3) 3154 with other cemented designs. All implants were cemented using high viscosity cement. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Matched cohorts were selected from the ATTUNE subsets (original and S+) and PFC groups using the nearest neighbor method for radiographic analysis. Radiographs were assessed to compare the presence of radiolucent lines in the Attune S+, standard Attune, and PFC implants.Abstract
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Total hip replacement (THR) is one of the most successful and cost-effective interventions in orthopaedic surgery. Dislocation is a debilitating complication of THR and managing an unstable THR constitutes a significant clinical challenge. Stability in THR is multifactorial and is influenced by surgical, patient and implant related factors. It is established that larger diameter femoral heads have a wider impingement-free range of movement and an increase in jump distance, both of which are relevant in reducing the risk of dislocation. However, they can generate higher frictional torque which has led to concerns related to increased wear and loosening. Furthermore, the potential for taper corrosion or trunnionosis is also a potential concern with larger femoral heads, particularly those made from cobalt-chrome. These concerns have meant there is hesitancy among surgeons to use larger sized heads. This study presents the comparison of clinical outcomes for different head sizes (28mm, 32mm and 36mm) in primary THR for 10,104 hips in a single centre. A retrospective study of all consecutive patients who underwent primary THR at our institution between 1st April 2003 and 31st Dec 2019 was undertaken. Institutional approval for this study was obtained. Demographic and surgical data were collected. The primary outcome measures were all-cause revision, revision for dislocation, and all-cause revision excluding dislocation. Continuous descriptive statistics used means, median values, ranges, and 95% confidence intervals where appropriate. Kaplan-Meier survival curves were used to estimate time to revision. Cox proportional hazard regression analysis was used to compare revision rates between the femoral head size groups. Adjustments were made for age at surgery, gender, primary diagnosis, ASA score, articulation type, and fixation method.Abstract
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We present a large single surgeon case series evaluation of a new growth guidance technique for the treatment of progressive early onset scoliosis (EOS). A traditional Luque trolley construct uses wires to hold growth guidance rods together. We describe a new technique that uses domino end to side connectors in place of the wires with the aim of providing a stronger construct to better limit curve progression, while allowing longitudinal growth. We did a thorough retrospective review of patient records and radiological imaging. Sequential measurements of Cobb angle and length of rods were recorded, as well as any further surgical procedures and associated complications. This enabled us to quantify the ability of a technique to limit curve progression and simultaneously allow growth of the construct. In total, 28 patients with EOS (20 idiopathic, four syndromic, and four neuromuscular) have been treated with this technique, 25 of whom have a minimum follow-up of 2 years and 13 have a minimum follow-up of 5 years. The average correction of the preoperative Cobb angle was 48.9%. At the 2-year follow up, the average loss of this initial correction was 15 degrees, rising to only 20 degrees at a minimum of 5 years (including four patients with a follow-up of 8 years or more). The growth of the constructs was limited. The average growth at 2 years was 3.7 mm, rising to 19 mm at the 5-year follow-up. Patients who underwent surgery with this technique before the age of 8 years seemed to do better. This group had a revision rate of only 18% at an average time of 7 years after the index procedure, and the average growth was 22 mm. However, the group that had index surgery after the age of 8 years had a 64% revision rate at an average of 3.2 years after surgery and an average growth of only 11.6 mm. Overall, in the cases series, there were four hardware failures (14%) and one deep infection (3.5%), and only ten patients (36%) had one extra surgery after the index procedure. Only two of the 13 patients who are at a follow-up of 5 years or more have had revision. This modified Luque trolley technique has a good capacity for initial curve correction and for limiting further curve progression, with limited longitudinal growth before 2 years and improved growth thereafter. This technique might not be so useful after the age of 8 years because of poor growth and a higher early revision rate. We have also demonstrated a low cost technique with a low hardware failure rate that saves many future surgeries for the patient compared with other techniques used in the treatment of EOS.
Complications after spinal fusion surgery are common, with implant loosening occurring in up to 50% of osteoporotic patients. Pedicle screw fixation strength reduces as a result of decreased trabecular bone density, whereas sublaminar wiring is less affected by these changes. Therefore, pedicle screw augmentation with radiopaque sublaminar wires (made with Dyneema Purity® Radiapque fibers, DSM Biomedical, Geleen, the Netherlands) may improve fixation strength. Furthermore, sublaminar tape could result in a gradual motion transition to distribute stress over multiple levels and thereby reduce implant loosening. The objective of this study is to test this hypothesis in a novel experimental setup in which a cantilever bending moment is applied to individual human vertebrae. Thirty-eight human cadaver vertebrae were stratified into four different groups: ultra-high molecular weight polyethylene sublaminar tape (ST), pedicle screw (PS), metal sublaminar wire (SW) and pedicle screw reinforced with sublaminar tape (PS+ST). The vertebrae were individually embedded in resin, and a cantilever bending moment was applied bilaterally through the spinal rods using a universal material testing machine. This cantilever bending setup closely resembles the loading of fixators at transitional levels of spinal instrumentation. The pull-out strength of the ST (3563 ± 476N) was not significantly different compared to PS, SW or PS+ST. The PS+ST group had a significantly higher pull-out strength (4522 ± 826N) compared to PS (2678 ± 292N) as well as SW (2931 ± 250N). The higher failure strength of PS + ST compared to PS indicates that PS augmentation with ST may be an effective measure to reduce the incidence of screw pullout, even in osteoporotic vertebrae. Moreover, the lower stiffness of sublaminar fixation techniques and the absence of damage to the cortices in the ST group suggest that ST as a stand-alone fixation technique in adult spinal deformity surgery may also be clinically feasible and offer clinical benefits.
After anterior cruciate ligament (ACL) rupture, reconstructive surgery with a hamstring tendon autograft is often performed. Despite overall good results, ACL re-rupture occurs in up to 10% of the patient population, increasing to 30% of the cases for patients aged under 20 years. This can be related to tissue remodelling in the first months to years after surgery, which compromises the graft's mechanical strength. Resident graft fibroblasts secrete matrix metalloproteinases (MMPs), which break down the collagen I extracellular matrix. After necrosis of these fibroblasts, myofibroblasts repopulate the graft, and deposit more collagen III rather than collagen I. Eventually, the cellular and matrix properties converge towards those of the native ACL, but full restoration of the ACL properties is not achieved. It is unknown how inter-patient differences in tissue remodelling capacity contribute to ACL graft rupture risk. This research measured patient-specific tissue remodelling-related properties of human hamstring tendon-derived cells in an in vitro micro-tissue platform, in order to identify potential biological predictors for graft rupture. Human hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions. These cells were seeded in collagen I gels on a micro-tissue platform to assess inter-patient cellular differences in tissue remodelling capacity. Remodelling was induced by removing the outermost micro-posts, and micro-tissue compaction over time was assessed using transmitted light microscopy. Protein expression of tendon marker tenomodulin and myofibroblast marker α-smooth muscle actin (αSMA) were measured using Western blot. Expression and activity of remodelling marker MMP2 were determined using gelatin zymography. Cells were obtained from 12 patients (aged 12–51 years). Patient-specific variations in micro-tissue compaction speed or magnitude were observed. Up to 50-fold differences in αSMA expression were found between patients, although these did not correlate with faster or stronger compaction. Surprisingly, tenomodulin was only detected in samples obtained from two patients. Total MMP2 expression varied between patients, but no large differences in active fractions were found. No correlation of patient age with any of the remodelling-related factors was detected. Remodelling-related biological differences between patient tendon-derived cells could be assessed with the presented micro-tissue platform, and did not correlate with age. This demonstrates the need to compare this biological variation in vitro - especially cells with extreme properties - to clinical outcome. Sample size is currently increased, and patient outcome will be determined. Combined with results obtained from the in vitro platform, this could lead to a predictive tool to identify patients at risk for graft rupture.
Novel biomaterials are being developed and studied, intended to be applied as bone graft substitute materials. Typically, these materials are being tested in in vitro setups, where among others their cytotoxicity and alkaline phosphatase activity (as a marker for osteoblastic differentiation) are being evaluated. However, it has been reported that in vitro tests correlate poorly with in vivo results and therefore many promising biomaterials may not reach the clinic as a bone graft substitute product. One of the reasons for the poor correlation, may be the minimal complexity of the in vitro tests, as compared to the in vivo environment. Ex vivo models, mimicking the natural tissue environment whilst maintaining control of culture parameters, may be a promising alternative to assess biomaterials for bone formation. Assess the possibility of an ex vivo culture platform to test biomaterials on their potential to stimulate new bone formation. Osteochondral plugs (cylinders n=10, Ø 10 mm, height 15 mm) were drilled from fresh porcine knees, from the slaughterhouse. A bone defect (Ø 6 mm) was created and which was filled with a biomaterial graft (S53P4 bioactive glass (n=3); collagen sponges loaded with BMP-2 (n=3, as positive control)) or kept empty (n=4). The explants were cultured in custom-made two-chamber bioreactors for six weeks (LifeTec Group BV). Cartilage and bone were physically separated, similar to the in vivo situation, by a sealing ring. The two tissues were cultured in separate compartments, allowing for specific culture medium for each tissue. Medium was changed every 2–3 days and weekly micro computed tomography (µCT) images were obtained to longitudinally monitor the formation of new bone. An MTT assay was performed on half of the samples after six weeks of culture. The other samples were fixed for histology, to determine which cells were present after six weeks. The MTT metabolic assay showed that a number of cells in the bone were viable after six weeks. The further away from the border, the fewer living cells were observed. The cells in the cartilage also survived. No significant bone formation was observed with µCT in either of groups, even though abundant bone formation was expected in the BMP-2 group. Explanations of the negative results of the positive group might be that too few viable cells remain after six weeks, or that the cells that are still present are not able to form bone. No significant bone formation was observed in the bone defects in osteochondral explants that were cultured with, or without, biomaterials for six weeks. However, the platform showed that it is capable to successfully culture osteochondral explants for six weeks. Histology needs to be performed to evaluate which cells were present at the end of the culture and this will be compared to the cells present directly after drilling the explants.
Currently, between 17% of patients undergoing surgery for adult spinal deformity experience severe instrumentation related problems such as screw pullout or proximal junctional failure necessitating revision surgery. Cables may be used to reinforce pedicle screw fixation as an additive measure or may provide less rigid fixation at the construct end levels in order to prevent junctional level problems. The purpose of this study is to provide insight into the maximum expected load during flexion in UHMWPE cable in constructs intended for correction of adult spine deformity (degenerative scoliosis) in the PoSTuRe first-in-man clinical trial. Following the concept of toppinoff, a new construct is proposed with screw/cable fixation of rods at the lower levels and standalone UHMWPE cables at the upper level (T11). A parametric FE model of the instrumented thoracolumbar spine, which has been previously validated, was used to represent the construct. Pedicle screws are modeled by assigning a rigid tie constraint between the rod and the lamina of the corresponding spinal level. Cables are modeled using linear elastic line elements, fixing the rod to the lamina medially at the cranial laminar end and laterally at the caudal laminar end. A Youngs modulus was assigned such that the stiffness of the line element was the same as that of the cable. An 8 Nm flexion moment was applied to the cranial endplate. The maximum value of the force in the wire (80 N) is found at the T11 (upper) level. At the other levels, forces in the cable are very small because most of the force is carried by the screw (T12) or because the wires are force shielded by the contralateral and adjacent level pedicle screws (L2, L3). The model provides first estimates of the forces that can be expected in the UHMWPE cables in constructs for kyphosis correction during movement. It is expected that this approach can help in defining the number of wires for optimal treatment.
The purpose of this investigation was to evaluate systematically the literature concerning biopsy, MRI signal to noise quotient (SNQ) and clinical outcomes in graft-maturity assessment after autograft anterior cruciate ligament reconstruction (ACLR) and their possible relationships. Methods: The systematic review was reported and conducted according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Studies through May 2019 evaluating methods of intra-articular ACL autograft maturity assessment were considered for inclusion. Eligible methods were histologic studies of biopsy specimens and conventional MRI studies reporting serial SNQ and/ or correlation with clinical parameters. Ten biopsy studies and 13 imaging studies, with a total of 706 patients, met the inclusion criteria. Biopsy studies show that graft remodeling undergoes an early healing phase, a phase of remodeling or proliferation and a ligamentization phase as an ongoing process even 1 year after surgery. Imaging studies showed an initial increase in SNQ, peaking at approximately 6 months, followed by a gradual decrease over time. There is no evident correlation between graft SNQ and knee stability outcome scores at the short- and long-term follow-up after ACLR. The remodeling of the graft is an ongoing process even 1 year after ACLR, based on human biopsy studies. MRI SNQ peaked at approximately 6 months, followed by a gradual decrease over time. Heterogeneity of the MRI methods and technical restrictions used in the current literature limit prediction of graft maturity and clinical and functional outcome measures by means of MRI graft SNQ after ACLR.
The angle of acetabular inclination is an important measurement in total hip replacement (THR) procedures. Determining the acetabular component orientation intra-operatively remains a challenge. An increasing number of innovators have described techniques and devices to achieve it. This paper describes a mechanical inclinometer design to measure intra-operative acetabular cup inclination. Then, the mechanical device is tested to determine its accuracy. The aim was to design an inclinometer to measure inclination without existing instrumentation modification. The device was designed to meet the following criteria: 1. measure inclination with acceptable accuracy (+/− 5o); 2. easy to use intra-operatively (handling & visualization); 3. adaptable and useable with majority of instrumentation kits without modification; 4. sterilizable by all methods; 5. robust/reusable. The prototype device was drafted by computer aided design (CAD) software. Then a prototype was constructed using a 3D printer to establish the final format. The final device was CNC machined from SAE 304 stainless steel. The design uses an eccentrically weighted flywheel mounted on two W16002-2RS ball bearings pressed into symmetrical housing components. The weighted wheel is engraved with calibrated markings relative to its mass centre. Device functioning is dependent on gravity maintaining the weighted wheel in a fixed orientation while the housing can adapt to the calibration allowing for determining the corresponding measurement. The prototype device accuracy was compared to a digital device. A digital protractor was used to create an angle. The mechanical inclinometer (user blinded to digital reading) was used to determine the angle and compared to the digital reading. The accuracy of the device compared to the standard freehand technique was assessed using a saw bone pelvis fixed in a lateral decubitus position. 18 surgeons (6 expert, 6 intermediate, 6 novice) were asked to place an uncemented acetabular cup in a saw bone pelvis to a target of 40 degrees. First freehand then using the inclinometer. The inclination was determined using a custom-built inertial measurement unit with the user blinded to the result. Comparison between the mechanical and digital devices showed that the mechanical device had an average error of −0.2, a standard deviation of 1.5, and range −3.3 to 2.6. The average root mean square error was 1.1 with a standard deviation of 0.9. Comparison of the inclinometer to the freehand technique showed that with the freehand component placement 50% of the surgeons were outside the acceptable range of 35–45 degrees. The use of the inclinometer resulted all participants to achieve placement within the acceptable range. It was noted that expert surgeons were more accurate at achieving the target inclination when compared to less experienced surgeons. This work demonstrates that the design and initial testing of a mechanical inclinometer is suitable for use in determining the acetabular cup inclination in THR. Experimental testing showed that the device is accurate to within acceptable limits and reliably improved the accuracy of uncemented cup implantation in all surgeons.
For many designs of total knee arthroplasty (TKA) it remains unclear whether cemented or uncemented fixation provides optimal long-term survival. The main limitation in most studies is a retrospective or non-comparative study design. The same is true for comparative trials looking only at the survival rate as extensive sample sizes are needed to detect true differences in fixation and durability. Studies using radiostereometric analysis (RSA) techniques have shown to be highly predictive in detecting late occurring aseptic loosening at an early stage. To investigate the difference in predicted long-term survival between cemented, uncemented, and hybrid fixation of TKA, we performed a randomized controlled trial using RSA. A total of 105 patients were randomized into three groups (cemented, uncemented, and hybrid fixation of the ACS Mobile Bearing (ACS MB) knee system, implantcast). RSA examinations were performed on the first day after surgery and at scheduled follow-up visits at three months, six months, one year, and two years postoperatively. Patient-reported outcome measures (PROMs) were obtained preoperatively and after two years follow-up. Patients and follow-up investigators were blinded for the result of randomization.Aims
Methods
Besides conventional radiographs, the use of MRI, CT, and bone scintigraphy is frequent in the diagnosis of a fracture of the scaphoid. However, which techniques give the best results remain unknown. The investigation of a new imaging technique initially requires an analysis of its precision. The primary aim of this study was to investigate the interobserver agreement of high-resolution peripheral quantitative CT (HR-pQCT) in the diagnosis of a scaphoid fracture. A secondary aim was to investigate the interobserver agreement for the presence of other fractures and for the classification of scaphoid fracture. Two radiologists and two orthopaedic trauma surgeons evaluated HR-pQCT scans of 31 patients with a clinically-suspected scaphoid fracture. The observers were asked to determine the presence of a scaphoid or other fracture and to classify the scaphoid fracture based on the Herbert classification system. Fleiss kappa statistics were used to calculate the interobserver agreement for the diagnosis of a fracture. Intraclass correlation coefficients (ICCs) were used to assess the agreement for the classification of scaphoid fracture.Aims
Methods
“Implant associated “We produced a set of 20 recombinant mAbs specific for staphylococcal antigens. Using flow cytometry and ELISA-based methods we determined the binding of these mAbs to planktonic staphylococci and Aim
Method
To retrospectively evaluate infection eradication rate of DAIR procedures performed in our tertiary referral center. We analyzed whether the outcome was influenced by time of infection after arthroplasty, previous surgery or causative pathogen. We retrospectively collected data of 81 patients treated with DAIR for periprosthetic joint infections after hip (n=48) and knee (n=33) arthroplasty between 2011 and 2017. Patients were divided into 3 groups: acute early infections (occurring <4 weeks, 29 cases), late chronic infections (occurring >4 weeks postoperative, 49 cases) and acute haematogenous infections (occuring >3 months after surgery with symptoms less than 4 weeks, 3 cases). Primary outcome was successful infection eradication after treatment within one year. Eradication failure was determined as unplanned subsequent surgery because of persistent infection, use of suppressive antibiotics or signs of infection at one year follow-up.Aim
Methods
Clinical researchers use Pfirrmann classification for grading intervertebral disc degeneration radiologically. Basic researchers have access to morphology and instead use the Thompson score. The aim of this study was to assess the inter-observer reliability of both classifications, along with their correlation. We obtained T2-weighted MR images of 80 human lumbar intervertebral discs with various stages of degeneration to assess the Pfirrmann-score. Then the discs were dissected midsagittally to obtain the Thompson-score. The observers were typical users of both grading systems: a spine surgeon, radiology resident, orthopaedic resident, and a basic scientist, all experts on intervertebral disc degeneration. Cohen's kappa (CK) was used to determine inter-observer reliability, and intra-class correlation (ICC) as a measure for the variation between the outcomes. For the Thompson score, the average CK was 0.366 and ICC score 0.873. The average inter-observer reliability for the Pfirrmann score was 0.214 (CK) and 0.790 (ICC). Comparing the grading systems, the intra-observer agreement was 0.240 (CK) and 0.685 (ICC).Purpose of study and background
Methods and Results
Method of fixation in THA is a contentious issue, with proponents of either technique citing improved implant survival and outcomes. Current comparisons rely on insufficiently powered studies with short-term follow up or larger poorly controlled registry studies. Patient factors are considered a key variable contributing to the risk of implant failure. One way to overcome this confounder is to compare the survival of cementless and cemented THAs patients who have undergone bilateral THAs with cemented hip on one side and cementless hip on the other. We compared stem survival of patients who have bilateral THA with one cemented stem in one hip and a cementless stem in the contralateral hip in the National Joint Registry. UK National Joint Registry is the largest registry of its kind in the world. This study included 2934 patients with 5868 THAs who underwent bilateral THAs s between 2003 and 2016. These patients had undergone bilateral sequential THAs within 3 years of each other: cemented THA on one side and cementless on the other, Patients had identical pre-operative American Society of Anaesthesiologists group for both THAs and same indication for surgery. Implant survival was compared using Cox regression with an endpoint of stem revision.Background
Methods
Intraoperative periprosthetic femoral fractures (IOPFF) lead to reduced implant survival. A deeper understanding of predictors enables surgeons to modify techniques and patient selection to reduce the risk of IOPFF. The aim of this study was to estimate predictors of IOPFF and each anatomical subtype (calcar crack, trochanteric fracture, femoral shaft fracture) during primary THA. This retrospective cohort study included 793823 primary THAs between 2004 and 2016. Relative risks for patient, surgical and implant factors are estimated for any IOPFF fracture and for all anatomical subtypes of IOPFF.Introduction
Methods
Here we describe a cohort study to determine the performance of a commercially available Fluorescence In Situ Hybridization (FISH)-kit on samples of 65 consecutive patients suspected of orthopedic implant associated infections (IAI). Culture is routinely used and has a high specificity and sensitivity but requires days to more than a week for slow growing bacteria. FISH results are available within 45–60 minutes and thus specific treatment can start immediately. In addition, previous antibiotic therapy may hinder culture while bacteria may still be detected by FISH. The hemoFISH-kit from Miacom diagnostics (Dusseldorf, Germany) was used on a total of 82 joint aspirates, sonication fluids and tissue samples of 65 consecutive patients to detect and identify possible microorganisms. This FISH-kit contains a universal 16S rRNA probe and species-specific probes for bacteria commonly encountered in blood infections. FISH and culture were compared to the clinical definition of IAI. These definitions were based on the criteria described by Pro-Implant Foundation criteria for IAI after fracture fixation or prosthetic joint infection. If no criteria were described in the literature for a specific IAI then MSIS criteria were used.Aim
Method
Adequate osseointegration of knee resurfacing implants for the treatment of focal cartilage defects is an important prerequisite for good clinical outcomes. Inadequate initial fixation and sustained micromotion may lead to osteolysis and ultimately implant failure. PET/CT with the bone seeking tracer 18F-sodium fluoride (18F-NaF) allows for localisation and quantification of abnormalities in bone metabolism. 18F-NaF PET/CT has been shown to correlate with loosening of implants in the hip and spine. Here, we asses osseointegration of the knee resurfacing implants using micro-computed tomography (µCT) and correlate µCT parameters to 18F-NaF uptake on PET/CT scans taken 3 and 12 weeks after surgery. We hypothesize that 18F-NaF uptake at 12 weeks and its relative decrease between 3 and 12 weeks correlates with osseointegration at 12 weeks postoperatively. Polymer implants with Young”s moduli approximately equal to- and below the Young's modulus of bone, with- and without surface modification were used in this study next to a control metal implant. Five different osteochondral implants were implanted bilaterally in critically-sized osteochondral defects in 16 goats. At 3 and 12 weeks postoperatively, a 10-minute static PET/CT-scan (Philips, Gemini TF PET/CT) was made 60 minutes after intravenous injection of 18F-NaF. Image processing resulted in an overall bone metabolism parameter, i.e. standardized uptake value (SUV). A cylindrical region of interest was drawn around each implant to obtain the maximum SUV (SUVmax). Bone quality parameters were quantified in a cylinder surrounding the implant using µCT after sacrifice as a measure for osseointegration. The in vivo 18F-NaF PET/CT uptake parameters were correlated to the bone quality parameters.INTRODUCTION
METHODS
Endochondral ossification in the growth plate is directly responsible for skeletal growth and its Healthy skeletally immature (5 weeks old) C57BL/6 mice were treated for ten weeks with celecoxib (daily oral administration 10 mg/kg) or placebo (water) (institutional approval 2013–094) (n=12 per group). At 15 weeks postnatally, total growth plate thickness, the thickness of specific growth plate zones, (immuno)histological analysis of extracellular matrix composition in the growth plate, cell number and cell size, longitudinal bone growth and bone micro-architecture by micro-CT were analysed. Inhibition of COX-2 activity was confirmed by determining PGE2 levels in plasma using an ELISA.INTRODUCTION
METHODS
Hip fractures cause significant morbidity and mortality, affecting 70,000 people in the UK each year. The dynamic hip screw (DHS) is used for the osteosynthesis of extracapsular neck of femur fractures, a procedure that requires complex psychomotor skills to achieve optimal lag screw positioning. The tip-apex distance (TAD) is a measure of the position of the lag screw from the apex of the femoral head, and is the most comprehensive predictor of cut-out (failure of the DHS construct). To develop these skills, trainees need exposure to the procedure, however with the European Working Time Directive, this is becoming harder to achieve. Simulation can be used as an adjunct to theatre learning, however it is limited. FluoroSim is a digital fluoroscopy simulator that can be used in conjunction with workshop bones to simulate the first step of the DHS procedure (guide-wire insertion) using image guidance. This study assessed the construct validity of FluoroSim. The null hypothesis stated that there would be no difference in the objective metrics recorded from FluoroSim between users with different exposure to the DHS procedure. This multicentre study recruited twenty-six orthopaedic doctors. They were categorised into three groups based on the number of DHS procedures they had completed as the primary surgeon (novice <10, intermediate 10≤x<40 and experienced ≥40). Twenty-six participants completed a single DHS guide-wire attempt into a workshop bone using FluoroSim. The TAD, procedural time, number of radiographs, number of guide-wire retires and cut-out rate (COR) were recorded for each attempt.Background
Methods
Training within surgery is changing from the traditional Halstedian apprenticeship model. There is need for objective assessment of trainees, especially their technical skills, to ensure they are safe to practice and to highlight areas for development. In addition, due to working time restrictions in both the UK and the US, theatre time is being limited for trainees, reducing their opportunities to learn such technical skills. Simulation is one adjunct to training that can be utilised to both assess trainees objectively, and provide a platform for trainees to develop their skills in a safe and controlled environment. The insertion of a dynamic hip screw (DHS) relies on complex psychomotor skills to obtain an optimal implant position. The tip-apex distance (TAD) is a measurement of this positioning, used to predict failure of the implant. These skills can be obtained away from theatre using workshop bone simulation, however this method does not utilise fluoroscopy due to the associated radiation risks. FluoroSim is a novel digital fluoroscopy simulator that can recreate digital radiographs with workshop bone simulation for the insertion of a DHS guide-wire. In this study, we present the training effect demonstrated on FluoroSim. The null hypothesis states that no difference will be present between users with different amounts of exposure to FluoroSim. Medical students were recruited from three London universities and randomised into a training (n=23) and a control (n=22) cohort. All participants watched a video explanation of the simulator and task and were blinded to their allocation. Training participants completed 10 attempts in total, 5 attempts in week one, followed by a one week wash out period, followed by 5 attempts in week 2. The control group completed a single attempt each week. For each attempt, 5 metrics were recorded; TAD, procedural time, number of radiographs, number of guide-wire retires and cut-out rate (COR).Background
Methods
Hip fractures affect 1.6 million people globally per annum, associated with significant morbidity and mortality. A large proportion are extracapsular neck of femur fractures, treated with the dynamic hip screw (DHS). Mechanical failure due to cut-out is seen in up to 7% of DHS implants. The most important predictor of cut-out is the tip-apex distance (TAD), a numerical value of the lag screw”s position in the femoral head. This distance is determined by the psychomotor skills of the surgeon guided by fluoroscopic imaging in theatre. With the current state of surgical training, it is harder for junior trainees to gain exposure to these operations, resulting in reduced practice. Additionally, methods of simulation using workshop bones do not utilise the imaging component due to the associated radiation risks. We present a digital fluoroscopy software, FluoroSim, a realistic, affordable, and accessible fluoroscopic simulation tool that can be used with workshop bones to simulate the first step of the DHS procedure. Additionally, we present the first round of accuracy tests with this software. The software was developed at the Royal National Orthopaedic Hospital, London, England. Two orthogonally placed cameras were used to track two coloured markers attached to a DHS guide-wire. Affine transformation matrices were used in both the anterior-posterior (AP) and cross table lateral (CTL) planes to match three points from the camera image of the workshop bone to three points on a pre-loaded hip radiograph. The two centre points of each marker were identified with image processing algorithms and utilised to digitally produce a line representing the guide-wire on the two radiographs. To test the accuracy of the system, the software generated 3D guide-wire apex distance (GAD) (from the tip of the guide-wire to a marker at the centre of calibration) was compared to the same distance measured with a digital calliper (MGAD). In addition, the same accuracy value was determined in a simulation scenario, from 406 attempts by 67 medical students.Background
Methods
Growth-guidance constructs are an alternative to growing rods for the surgical treatment of early onset scoliosis (EOS). In growth-guidance systems, free-sliding anchors preserve longitudinal spinal growth, thereby eliminating the need for surgical lengthening procedures. Non-segmental constructs containing ultra-high molecular weight polyethylene (UHMWPE) sublaminar wires have been proposed as an improvement to the traditional Luque trolley. In such a construct, UHMWPE sublaminar wires, secured by means of a knot, serve as sliding anchors at the proximal and distal ends of a construct, while pedicle screws at the apex prevent rod migration and enable curve derotation. Ideally, a construct with the optimal UHMWPE sublaminar wire density, offering the best balance between providing adequate spinal fixation and minimizing surgical exposure, is designed preoperatively for each individual patient. In a previous study, we developed a parametric finite element (FE) model that potentially enables preoperative patient-specific planning of this type of spinal surgery. The objective of this study is to investigate if this model can capture the decrease in range of motion (ROM) after spinal fixation as measured in an experimental study. In a previous INTRODUCTION
MATERIALS AND METHODS
Bio-Active Glass (BAG) is a promising bone graft substitute for large bone defect reconstruction because of its favourable osteoconductive, antibacterial and angiogenic properties. Potentially, it could also mechanically reinforce the defect, thus making it suitable for load-bearing defects. However, the mechanical properties of the reconstructive layer consisting of BAG/bone allograft mixtures are unknown. The goals of this study therefore were, first, to measure the mechanical properties of different BAG/bone graft mixtures and, second, to investigate to what extent such mixtures could reinforce distal tibial defects using micro-FE analysis and high-resolution CT scans. Four different BAG/bone graft mixtures were impacted in a cylindrical holder, mechanically tested in confined compression and scanned with micro-CT. From these images, bone graft material and glass were segmented using two different threshold values. The interface between bone and BAG was modelled separately by dilating the glass phase. Micro-Finite-Element (FE) models of the composites were made using a Young's modulus of 2.5 GPa for bone and 35 GPa for BAG. The Young's modulus for the interface region was determined by fitting experimental and micro-FE results for the same specimens. (82 μm resolution) CT scans of a 9 mm region of the distal tibia of 3 subjects were used. Micro-FE models of this region were made to determine its stiffness in the original state, with a simulated cortical defect and after a mixture of BAG/bone was modelled in the defect.Background
Materials and Methods
Finite element (FE) models have become a standard pre-clinical tool to study biomechanics of spine and are used to simulate and evaluate different strategies in scoliosis treatment: examine their efficacy as well as the effect of different implant design parameters. The goal of this study is to investigate, in a system of rods and laminar wires, the effect of the number of wires and their pre-stress on whole spine stiffness. A generic FE model was developed to represent a full human spine, including vertebrae, intervertebral discs, ligaments, facet and costovertebral joints, and ribcage. Intervertebral discs were modeled with 3D rebar elements with linear elastic material properties. Vertebrae, ribs, sternum, facet joints, cartilage and endplates were modeled with brick elements, and costal muscles with shell elements with linear elastic properties. Furthermore, ligaments were modeled with truss elements with nonlinear hypo-elastic properties. The spine model was instrumented from T7 to T12 with rods and wires modeled as titanium. Nonlinear contact properties were defined for rib neck-vertebra, transverse processes-rib and facet joint sets. The FE model was loaded in flexion and the whole spine instantaneous stiffness was calculated for different wire pre-stressing levels (0.1 to 2 MPa). Similar analyses were performed with changed numbers of wires and whole spine stiffness was calculated.Background
Methods
Traditional TKR designs exhibit abnormal and unpredictable kinematics: with posterior subluxation in extension and anterior slide with flexion. These can contribute to restricted knee flexion and reduced quadriceps efficiency. Newer designs attempt to provide “guided motion” with the aim of mimicking normal knee kinematics. The Journey (Smith & Nephew) BCS TKR incorporates both an anterior and a posterior cam/post mechanism while Triathlon PS TKR (Stryker) incorporates a posterior cam/post mechanism. This study compares the in-vivo kinematics of these two designs and compares it with normal knee. Knee kinematics of 10 patients with Journey-BCS TKR and 11 patients with Triathlon PS TKR; all with excellent clinical outcome (average age: 65) were analysed. Patients underwent fluoroscopic assessment of the knee during a step-up and deep knee bend exercise. 2D fluoroscopic images were recorded. Data was analysed for patella tendon angle (PTA) and contact points using a 3D model fitting technique. This data was compared to normal knee kinematics (n=20).Introduction
Methods
This study reports a clinical comparison of new and old establishing whether this modified implant has maintained the established normal kinematic profile of the Oxford UKR.
Knee kinematics were assessed by analysing the movement of the femur relative to the tibia using the PTA.
This study assesses the functional in vivo kinematics of Advanced Medial Pivot (AMP) TKR and compares it to kinematics of the normal knee.
From 1990 to 1993 we treated 22 consecutive patients who had progressive spinal kyphosis due to ankylosing spondylitis by a closing-wedge posterior vertebral osteotomy with partial corporectomy of L4 and transpedicular fixation. The average correction was 32 degrees (24 to 52) with a mean loss of correction after operation of 2.7 degrees (0 to 13). The average operating time was 185 minutes (135 to 240) and blood loss was 2500 ml (1200 to 5000). The osteotomy corrected all patients sufficiently to allow them to see ahead and their posture was improved. There were no fatal complications, but in two cases there was failure of the instrumentation and one patient needed reoperation for nerve compression. Two deep wound infections required removal of the implant and six patients had superficial skin infections under the plaster. The use of a circoelectric bed and intermittent prone lying eliminated this problem.
We report the operative technique and results of a new method of central grafting for persistent nonunion of the tibial shaft. The operation is performed through a lateral approach, anterior to the fibula. Fresh autogenous bone from the iliac crest is used to form a central bridge between the tibia and fibula above, below and at the level of the nonunion. In 48 tibiae, most with long-standing nonunion and some with infection or bone defects, sound healing was obtained in 45 after one operation. Only one failure needed amputation.
In 139 patients with burst fractures of the thoracic, thoracolumbar or lumbar spine, the least sagittal diameter of the spinal canal at the level of injury was measured by computerised tomography. By multiple logistic regression we investigated the joint correlation of the level of the burst fracture and the percentage of spinal canal stenosis with the probability of an associated neurological deficit. There was a very significant correlation between neurological deficit and the percentage of spinal canal stenosis; the higher the level of injury the greater was the probability. The severity of neurological deficit could not be predicted.
Subperiosteal osteoid osteoma in a juxta-articular site presents a diagnostic challenge. The clinical features of joint stiffness, synovitis, muscle atrophy and local warmth may suggest arthritis rather than osteoid osteoma, while radiographs, bone scans and angiograms may not be diagnostic. We describe four cases of this rare condition.
1. In ten healthy young men an experimental paralysis of the supraspinatus muscle was induced with the aid of Xylocaine injected in or near the suprascapular nerve. 2. The completeness of the paralysis was checked by electromyography. 3. With the supraspinatus muscle completely eliminated, all subjects could move the arm against gravity through its full range in the shoulder joint, though the force and the power of endurance during abduction were diminished. 4. It is concluded that the role of the supraspinatus muscle is of a quantitative nature only.
1. The effects of heavy training on a skeletal muscle have been studied in the rat. After denervation of the triceps surae muscle the tendon of the plantaris muscle was implanted into the tuberosity of the calcaneum. It was then possible to demand an unusual performance of the plantaris, the weight of which is only 18 per cent of the weight of the triceps surae. 2. Formation of new muscle fibres was observed after prolonged heavy training. This is incontrast to the opinion of most investigators, who have seen no new fibres formed after training. Degenerative changes followed by regeneration were also seen. 3. The trained muscle could almost double its weight, and treble its force. Paradoxically, the supposedly non-contractile sarcoplasm was seen to have increased after training. 4. Training induced a strong protein synthesis in muscle. In normal muscle protein synthesis can hardly be demonstrated. 5. Connective tissue grew between single muscle fibres in the heavily trained muscle. Its distribution was unequal. 6. Heavy exercise caused marked swelling of an untrained muscle. 7. Functional recovery was satisfactory after the operation. This showed that a muscle can be replaced by one only one-fifth its weight, provided the latter is trained adequately. 8. Not even the most arduous training could inflict permanent damage on the muscle.