Aim. Arthroscopic interventions have revolutionized the treatment of joint pathologies. The appropriate diagnostics and treatment are required for infections after ligament reconstructions using non-resorbable material such as tendon grafts, anchors, and sutures, prone to biofilm formation. The infection rate is around 1% for knee and shoulder, while up to 4% for Achilles tendon reconstructions. Despite high number of these procedures worldwide, there is limited evidence about the best treatment protocol. Our study aimed to provide a general protocol for the treatment of small implants for soft tissue reconstruction. Method. Between 2019 and 2023, we treated 48 infections of ligament, meniscus, and tendon reconstructions out of 7291 related procedures performed in the same time period. Early infection (<30 days) were treated with an arthroscopic debridement and implant retention (DAIR), except Achilles tendons had open DAIR, while those with delayed or chronic infection (>30 days) were treated with extensive debridement and lavage combined with one-stage exchange (OSE) or implant removal. During surgery, at least 5 microbiological s and samples for histopathology were obtained. The removed material was sonicated. After surgery, all patients were one week on iv. antibiotics, followed by oral antibiofilm antibiotics for 6 weeks including rifampicin and/or a quinolone. All patients were followed for at least 1 year. Failure was defined as the need for additional revision surgery after finished iv. antibiotic treatment. Results. Among 48 patients, 38 were early and 10 were late acute or chronic infections. The incidence of infection for our cohort was 0.7%. We observed 27 infections after ligament reconstruction of the knee, 15 of the shoulder, 5 of the ankle, and 1 infection of the elbow joint. 40 patients were treated with DAIR, 5 with OSE, and 3 with implant removal. We had 11 C. acnes, 10 S. aureus, 6 S. epidermidis, 2 P. aeruginosa, 2 S. lugdunensis, 10 mixed flora, and 3 culture-negative infections. 12 patients received antibiotics before surgery, and all culture-negative infections were related to this subgroup. We observed 2 failures, both in a combination of proximal tibial osteotomy and ligament reconstruction of the knee joint. The success rate of our protocol was 96%. Conclusions. Prompt surgical treatment followed by 6 weeks of antibiotic treatment cured 96% of infections of small implants after reconstruction procedures of knee, shoulder, and ankle joints. Our study is the first to provide a treatment protocol for infections of small implants after ligament reconstruction procedures

Introduction. Recently, computer-aided orthopaedic surgery has enabled three dimensional (3D) preoperative planning, navigation systems and patient matched instrument, and they provide good clinical results in total knee arthroplasty. However, the preoperative planning methods and the criteria in total elbow arthroplasty (TEA) still have not sufficiently established due to the uncertainty of 3D anatomical geometry of the elbow joints. In order to clarify the 3D anatomical geometry, this study measured 3D bone models of the normal elbow joints. Additionally this study attempted to apply the 3D preoperative planning to ordinary surgery. Then the postoperative position of implant has evaluated as compared with the position in 3D preoperative planning. Methods. Three dimensional bone measurements on 4 normal cases were performed. Three dimensional bone models were constructed with CT image using Bone Viewer®(ORTHREE Co., Ltd.). TEA was performed with FINE® Total Elbow System (Nakashima Medical Co., Ltd.) for 3 rheumatoid arthritis (RA) cases (Fig. 1). Three dimensional preoperative planning was based on this bone measurement, and postoperative position of implant were evaluated. The postoperative assessments were evaluated by superimposing preoperative planning image on postoperative CT image using Bone Simulator® (ORTHREE Co., Ltd.). This study only covers humeral part. Results. The results of 3D bone measurements on 4 normal cases shows the average internal rotation angle between the flexion-extension axis and the epicondyles axis in the distal humerus was 2.2 degrees. The average valgus tilt of the distal humerus was 3.7 degrees. Postoperative position of humeral component for 3 RA cases was installed at proximal and valgus position compared to the preoperative planning. Discussion. This study indicates that ordinary two dimensional criteria and 3D anatomical one in the elbow joint may be different in several bony landmarks such as rotation, varus and valgus. Additionally these results show the differences between postoperative position of implant and preoperative position in 3D planning. More studies need to be conducted to validate postoperative evaluation and preoperative planning

We investigated whether an alternative tension band wire technique will produce greater compression and less displacement at olecranon (elbow) fracture sites compared to a standard figure of eight tension band technique. Olecranon fractures are commonly treated with tension band wiring using stainless steel wire in a figure of eight configuration. However recently published studies have raised doubts over the validity of the tension band concept proving that the standard figure of eight configuration does not provide fracture compression when the elbow is flexed. We propose an alternative tension band technique where the figure of eight is applied in a modified configuration producing greater compression across the fracture. An artificial elbow joint was simulated using artificial forearm (ulna) and arm (humerus) bones. The design simulated the action of the muscles around the elbow joint to produce flexion and extension. There were two arms to this investigation. (1) Standard tension band wire configuration with stainless steel. (2) Modified tension band wire configuration with stainless steel. The simulated elbow was put through a range of movement and sensors measured the compression at the articular and non-articluar surfaces of the fracture. Measurements were taken for compression with different weights applied to challenge both the techniques of tension band wiring. Measurements from the non articular surface of the fracture demonstrated greater compression with alternative tension band technique. However it was not statistically significant (ANOVA). Compression at the articular surface of the fracture exhibited statistically significant (p<0.05) greater compression with the alternative technique. Neither technique produced greater compression during flexion of the simulated elbow. The alternative tension band wiring technique proved superior in providing greater compression over the fracture site

We report the case of a 12-year-old boy with flexion loss in the left elbow caused by deficient of the concavity corresponding to the coronoid fossa in the distal humerus. The range of motion (ROM) was 15°/100°, and pain was induced by passive terminal flexion. Plain radiographs revealed complete epiphyseal closure, and computed tomography (CT) revealed a flat anterior surface of the distal humerus; the coronoid fossa was absent. Then, the bony morphometric contour was surgically recreated using a navigation system and a three-dimensional elbow joint model. A three-dimensional model of the elbow joint was made preoperatively and the model comprising the distal humerus was milled so that elbow flexion flexion of more than 140° could be achieved against the proximal ulna and radius. Navigation-assisted surgery (contouring arthroplasty) was performed using CT data from this milled three-dimensional model. Subsequently, an intraoperative passive elbow flexion of 135° was obtained. However, active elbow flexion was still inadequate one year after operation, and a triceps lengthening procedure was performed. At the final follow-up one year after triceps lengthening, a considerable improvement in flexion was observed with a ROM of −12°/125°. Plain radiographs revealed no signs of degenerative change, and CT revealed the formation of the radial and coronoid fossae on the anterior surface of the distal humerus. Navigation-assisted surgery for deformity of the distal humerus based on a contoured three-dimensional model is extremely effective as it facilitates evaluation of the bony morphometry of the distal humerus. It is particularly useful as an indicator for milling the actual bone when a model of the mirror image of the unaffected side cannot be applied to the affected side as observed in our case

Objective:. Total elbow joint arthroplasty has limited longevity and is therefore not appropriate for younger rheumatoid arthritis patients. Arthroplasty using an inter-positional membrane may be another surgical option for this population. However, clinical results for joint arthroplasty using the inter-positional membrane have not traditionally been favorable because rheumatoid activity could not be controlled. Today, rheumatoid activity can be controlled with biologics; therefore, the utility of the inter-positional membrane procedure was re-evaluated. Methods:. An 8×6 cm sheet of fascia was detached from the patient's tensor fascia lata muscle to produce a JK membrane. The fascia was stretched on a frame and kept in a 2% chromic acid potassium solution for 24 hours. Then, the fascia was exposed to direct sunlight in order to reduce the dichromic acid. The fascia was washed out in running water for 24 hours and was then stored in phenol with the addition of 70% alcohol. Elbow arthroplasties were performed on three elbow joints in two young female patients. The first case had a significantly damaged right elbow joint with severe joint dysfunction. A JK membrane arthroplasty was done for the first case in 2003, when this patient was 34 years old. Biologics were administered with methotrexate after the surgery. The second case demonstrated bilateral ankylosed elbows due to idiopathic juvenile arthritis. Bilateral JK membrane arthroplasties were performed in 2010, when this patient was 32 years old. Several operative and manual manipulations were necessary in order to increase the range of motion following surgery. Biologics were administered with cyclosporine. Results:. Joint function was significantly improved in all three joints without pain after the JK membrane elbow arthroplasties. In case one, the JOA (Japan Orthopaedic Association) elbow score improved from 21 points before surgery to 85 points after surgery and active elbow flexion improved to 110 degrees following surgery. In case two, the JOA elbow score was 55 and 82 points in the right elbow and 52 and 83 points in left elbow before and after surgery, respectively. In case two, active flexion improved to 120 degrees for the right elbow and 110 degrees for the left elbow following surgery. RA was well controlled in both patients. Conclusion:. Elbow arthroplasty using an inter-positional membrane appears to be useful in young patients when RA activity is controlled with biologics

Clinical assessment of elbow deformity in children at present is mainly based on physical examination and plain X-ray images, which may be inaccurate if the elbow is not in fully supination; furthermore, the rotational deformity is even harder to be determined by such methods. Morrey suggested that the axis of rotation of the elbow joint can be simplified to a single axis. Based on such assumption, we are proposing a method to assess elbow deformity using rotational axis of the joint, and an optimized calculation algorithm is presented. The rotation axis of elbow in respective to the upper arm can be obtained from the motion tract of markers placed at the forearm. Cadaver study was done, in which three skeletal motion trackers were placed over both the anterior aspect of humerus, as well as distal ulna. Osteotomy was created at the supracondylar region of humerus through lateral approach, and the bone fragments were stabilized with a set of external skeletal fixator, leaving the soft tissue intact. The amount of deformity was created manually by adjusting the position of the distal fragment via skeletal fixator. Ultrasound 3D motion tracking system from Zebris® was used in this study, and the program was developed under the Matlab environment. Cycles of passive elbow flexion/extension motion were carried out for each set of deformity. The data were initially transformed to humerus coordinate, and since the upper arm was not absolutely stationary, its influence on the measured position of ulna was adjusted. With this adjusted data, a best fit plane that would include most of the ulna positions (MU) within a minimal distance was obtained. The rotation axis was calculated as the normal vector to this plane, and the carrying angle could subsequently be assessed according to the relationship between this axis and the x-axis on the xy-plane as well as on the xz-plane. Fresh frozen cadaver study was conducted in the Medical Simulation Center at Tzu-Chi University. After adjustment of the raw data to eliminate the influence of humerus motion, the ulna motion could be narrowed down from a band of 10mm to 3mm, with a significant smaller standard deviation. The rotation axis was obtained by the normal vector to the best fit plane. Two different approaches were attempted to find the plane. In the first method, the plane was obtained via least square method from the adjusted ulna positions, and the second method found the plane via RANSAC method. Calculations were repeated several times for each method, and the results showed a variation of 5 degrees in the first method and about 2 degrees in the second method. Rotational axis can be used to define the 3-dimensional deformity of elbow joint; however, it is difficult to obtain such axis accurately due to hypermobility and multi-directional motion of the shoulder joint. In this study, we have developed another method to assess the elbow deformity using motion analysis system instead of the conventional image studies, and this may be applicable clinically if the facility becomes more accessible in the future. (This research was supported by the project TCRD-TPE-99-30 granted by the Buddhist Tzu-Chi General Hospital, Taipei Branch)

Aim. The incidence of hematogenous periprosthetic joint infections (hPJI) is unknown and the cases probably largely underreported. Unrecognized and untreated primary infectious foci may cause continuous bacteremia, further spread of microorganisms and thus treatment failure or relapse of infection. This study aimed at improving knowledge about primary foci and microbiological characteristics of this entity to establish preventive measures and improve diagnostic and therapeutic strategies to counteract hPJI. Method. We retrospectively analysed all consecutive patients with hPJI, who were treated at our institution from January 2010 until December 2016. Diagnosis of PJI was established if 1 of the following criteria applied:(i) macroscopic purulence, (ii) presence of sinus tract, (iii) positive cytology of joint aspirate (>2000 leukocytes/μl or >70% granulocytes), (iv) significant microbial growth in synovial fluid, periprosthetic tissue or sonication culture of retrieved prosthesis components, (v) positive histopathology. PJI was classified as hematogenous if the following criteria were fulfilled additionally: (1) onset of symptoms more than 1 month after arthroplasty AND (2) i) isolation of the same organism in blood cultures OR ii) evidence of a distant infectious focus consistent with the pathogen. Results. A total of 70 episodes of hPJI were included. Median age was 74 years (32–89 years), 36 were women and 29 men. Sites of PJI included 39 knees, 29 hips, one shoulder and one elbow joint. The pathogen was identified in 99% (n=69), the majority of episodes was monomicrobial (n=64, 91%). Blood cultures were collected in 39 cases (56%) and identified the pathogen in 67% (n=26). Isolated pathogens were Staphylococcus aureus (n=29), Streptococcus spp. (n=20) and Enterococcus faecalis (n=12), coagulase-negative staphylococci (n=6) and gram-negative bacilli (n=5). In 55% the primary focus was identified and included an intravascular (endocarditis, endoplastitis, thrombophlebitis; n=15), urogenitary (n=8), dental (n=6), gastrointestinal (n=5) and osteoarticular (n=2) and skin and soft tissue origin (n=1). The primary focus could not be identified in 29 cases (41%), primarily due to underuse of diagnostic workup. Conclusions. Causative agents were identified in the vast majority of hPJI with a predominance (75%) of high virulent microorganisms such as staphylococci, streptococci and gram-negative bacilli. Our results highlight the importance of a meticulous diagnostic workup including collection of blood cultures and performance of echocardiography in hematogenous PJI in order to cure the infection and prevent relapse. Awareness must be raised with regard to every prosthesis being endangered by hematogenous seeding from a distant infectious focus during the entire indwelling time

As a treatment for end-stage elbow joint arthritis, total elbow replacement (TER) results in joint motions similar to the intact joint; however, bearing wear, excessive deformations and/or early fracture may necessitate early revision of failed implant components. Compared to hips, knees and shoulders, very little research has been focused on the evaluation of the outcomes of TER, possible failure mechanisms and the development of optimal designs. The current study aims to develop computational models of TER implants in order to analyze implant behaviour; considering contact stresses, plastic deformations and damage progression. A geometrical model of a TER assembly was developed based on measurements from a Coonrad-Morrey TER implant (Zimmer, Inc., Warsaw, IN). Ultra high molecular weight polyethylene (UHMWPE) nonlinear elasto-plastic material properties were assigned to the humeral and ulnar bushings. A frictional penalty contact formulation with a coefficient of friction of 0.04 was defined between all of the surfaces of the model to take into account every possible interaction between different implant components in vivo. The loading scenario applied to the model includes a flexion-extension motion, a joint force reaction with variable magnitude and direction and a time varying varus-valgus (VV) moment with a maximum magnitude of 13 N.m, simulating a chair-rise scenario as an extreme loading condition. An explicit dynamic finite element solver was used (ABAQUS Explicit, Dassault Systèmes, Vélizy-Villacoublay, France), due to improved capabilities when performing large deformation analyses. Model results were compared directly with corresponding experimental data. Experimental wear tests were performed on the abovementioned implants using a VIVO (AMTI, Watertown, MA) six degree-of-freedom (6-DOF) joint motion simulator apparatus. The worn TER bushings were scanned after the test using micro computed tomography (µCT) imaging techniques, and reconstructed as 3D models. Comparisons were made based on the sites of damage and deformed geometries between the numerical results and experimental test data. In addition to that, parametric geometrical models were developed using worn geometry of the retrievals in order to account for primary wear and deformations while simulating long-term contact stress and secondary damage progression on the bushings (Fig. 1). Contact pressure distributions on the humeral and ulnar bushings correlate with the sites of damage as represented by the µCT data and gross observation of clinical retrievals. Furthermore, deformation patterns and kinematics of the components are in good agreement with the experimental results (Fig.2). Excessive plastic deformations are evident in both the numerical and the experimental results close to the regions with high contact pressures. Simulating parametric initially-worn geometries results in the formation of secondary damage zones, as well as redistribution of contact stresses and contact locations (Fig. 3). The results demonstrate UHMWPE bushing damage due to different loading protocols. Numerical results demonstrate strong agreement with experimental data based on the location of deformation and creep on bushings and exhibit promising capabilities for predicting the damage and failure mechanisms of TER implants. For figures/tables, please contact authors directly.

Introduction. Hemiarthroplasty is a treatment option for comminuted fractures and non-unions of the distal humerus. Unfortunately, the poor anatomical fit of off-the-shelf distal humeral hemiarthroplasty (DHH) implants can cause altered cartilage contact mechanics. The result is reduced contact area and higher cartilage stresses, thus subsequent cartilage erosion a concern. Previous studies have investigated reverse-engineered DHH implants which reproduce the shape of the distal humerus bone or cartilage at the articulation, but still failed to match native contact mechanics. In this study, design optimization was used to determine the optimal DHH implant shape. We hypothesized that patient-specific optimal implants will outperform population-optimized designs, and both will optimize simple reverse-engineered designs. Methods. The boney geometries of six elbow joints were created based on cadaver arm CT data using a semi-automatic threshold technique in 3D Slicer. CT scans were also obtained with the elbows denuded and disarticulated, such that the high contrast between hydrated cartilage and air could be exploited in order to reconstruct cartilage geometry. Using this 3D model data, finite element contact models were created for each elbow, where bones (distal humerus, proximal ulna and radius) were modelled as rigid surfaces covered by non-uniform thickness layers of cartilage. Cartilage was modelled as a Neo-Hookean hyperelastic material (K = 0.31 MPa, G = 0.37 MPa), and frictionless contact was assumed. In order to simulate hemiarthroplasty, the distal humerus cartilage surface was replaced by either a rigid surface in the shape of the subchondral bone (bone reverse engineered or BRE design), or a surface offset from the bone by some distance, which was defined parametrically and modified by an optimization algorithm. Simple flexion-extension with constant balanced muscle loads was simulated in ABAQUS (Fig 1), and resulting contact areas and contact stresses were calculated. For each specimen, the contact mechanics of the intact and DHH reconstructed joints were calculated. A design optimization algorithm in Matlab was used to determine the optimal offset distance which resulted in contact stress distributions on the ulna and radius which most closely resembled their intact conditions. This procedure was repeated in order to generate specimen-optimal offsets, as well as population-optimal offsets. Results. The population-optimal offset distance was 0.72 mm; whereas the specimen-optimal offsets ranged from 0.52 to 1.04 mm. Compared to the BRE design, which is effectively an offset distance of 0 mm, contact area generally increased at both the ulna (Fig 2) and radius (Fig 3) when either optimized design was used. On average, the specimen-optimal implant designs yielded only slightly larger contact areas than the population-optimal offsets, and only at mid-flexion (40–60 deg). Neither optimization strategy increased contact areas to those of the intact joint. Conclusions. Design optimization is a promising technique for improving patient-specific implants by offering customization in terms of contact mechanics, instead of simply reproducing osseous geometry. In this study, our models predict a large increase in contact area if optimal offsets are used when designing subject-specific DHH, and a population-optimal offset distance seems to be just as good as a subject-optimal offset. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Background. External fixation for a fracture-dislocation to a joint like the elbow, while maintaining joint mobility is currently done after identifying the center of rotation under X-ray guidance, when applying either a mono-lateral or a circular fixator. Current treatment. using the galaxy fixation system by Orthofix, the surgeon needs to correctly identify the center of rotation of the elbow under X-ray guidance on lateral views. If the center of rotation of the fixator is not aligned with that of the elbow joint, the assembly will not work, i.e. the elbow will be disrupted on trying to achieve flexion or extension movements. Figures (A, B, C and D) summarize the critical steps in identifying the centre of rotation (Courtesy of Orthofix Orthopedics International). New design. This new idea aims to propagate the principle of sliding external fixation applied on the extensor side of a joint, with the limbs of the fixator being able to slide in and out during joint extension and flexion respectively, without hindering the joint movement. Taking the ulno-humeral joint as an example, it is enough to apply the sliding external fixator in line with the subcutaneous border of the ulna, and the pins in the sagital plane, without the need to use x-ray guidance to identify the center of rotation, which simplifies the procedure, and makes it less technically demanding. The sliding external fixator over the elbow involves two bars which accommodate half pins fixation with headless grip screws to hold the pins, identical to the Rancho cubes technique by Smith & Nephew, these slide snugly into sleeves, those sleeves linked together through a hinge behind the elbow, and the bars are spring loaded to the hinge through the inside of the sleeves, which means they will slid into the sleeves in extension and out in flexion. Length of the sleeve should prevent the bars from dislodgement, and the cross section of both the bars and the sleeves have to correspond to each other for the sleeves to accommodate the bars within them and to prevent rotational instability within the construct itself. Summary. Applying an external fixator on the extensor surface is an idea could lead to major changes in external fixation product design, the ulno-humeral joint is taken as an example, and other joints could also be addressed taking in consideration joint size and anatomical structures at risk. The sliding technique makes the application easier, without the need to X-ray guided identification of the center of rotation

Background. Total elbow arthroplasty (TEA) has become an established procedure in the treatment of patients with rheumatoid arthritis (RA). However, there is little information on whether limited extension of the elbow affects clinical outcome scores after TEA and what causes the limited extension. Methods. We retrospectively analyzed fifty-four cases of primary TEA in patients with RA. There were seven men and thirty-nine women with a mean age of 63.6 years (range, thirty to eighty years). Thirty-seven of Coonrad-Morrey and seventeen of Discovery prostheses were used. The mean length of follow-up was 7.1 ± 4.0 years (range 2.0–14.6 years). Mayo Elbow Performing Score (MEPS) and radiological measurements were recorded. Anteroposterior and lateral radiographs were assessed before and after the operation and at the latest follow-up. Widening of the joint space was calculated by subtracting the length measured on the postoperative radiograph from that on the preoperative radiograph. Results. MEPS was significantly improved after surgery (51.2 to 91.1), especially in the domains of pain (18.6 to 43.1), stability (5.9 to 10) and daily function (10.7 to 21.0). Range of motion was significantly improved, in flexion (111.3° to 140.6°), pronation (62.1° to 72.3°), and supination (60.2° to 72.3°), but not in extension (30.0° to 28.8°). Simple and multivariate analyses showed that longer disease duration (p = 0.004), higher Larsen grade (p = 0.013), worse pronation/supination arc (p = 0.004) and worse postoperative extension (p = 0.033), but not postoperative flexion (p = 0.532), were significantly correlated with lower MEPS daily function. Conversely, simple and multivariate analyses showed that worse postoperative extension was correlated with lower MEPS daily function (p = 0.005) and worse preoperative extension (p < 0.001). Radiological analyses showed that, in the limited extension group (≧40°), the degree of extension was correlated with radiological widening of the joint. Conclusions. In linked TEA, perioperative widening of the elbow joint caused limited extension and worse daily function in patients with RA

Background. For correction of cubitus varus deformity many types of osteotomies and fixation methods have been described, but besides technical difficulties, they have limitations such as non-union, stiffness of the elbow joint and neurovascular injury. The prominence of the lateral condyle can also give rise to a poor cosmetic result. To overcome these problems, we reviewed the results of simple dome osteotomy with fixation by cross pins. Methods. From 2003 to 2007, eleven children with cubitus varus deformity having full range of movements and good elbow function had surgery. The average age was 9.2 years (range, 7 to 13) and M:F ratio was 4:1. Through a posterior triceps splitting approach a dome-shaped osteotomy is fashioned, the distal part of humerus is aligned as planned and then fixation by cross pinning is achieved. Patients were followed for two years. Pre-operative and post-operative humeral-elbow angles, ranges of motion and lateral prominence indices were compared. The results were evaluated according to the modified criteria of Oppenheim et al. Results. There were 8 excellent and 3 good results. The average correction of the humeral-elbow angle was 32.5° (range, 22 to 45), post-operative angle was 10.4°, and 8.4° at final follow-up. The average increase in the lateral prominence index was 20.8%, and when compared to the normal side, it was 12.3% greater. None of the children had lateral prominence of greater than 5 mm. Two of the cases developed transient ulnar nerve neuropraxia. Conclusion. The dome-shaped osteotomy fixed by crossed pins is a relatively simple procedure and obtains three dimensional correction of the deformity. The osteotomy site is inherently more stable than a lateral wedge osteotomy and less technically demanding as compared to step cut osteotomy. This is also effective in minimising the lateral condylar prominence

Purpose. Radial head implant over-lengthening, a common cause of capitellar wear and clinical failure, is difficult to diagnose using radiographs of the injured elbow. The purpose of this study was to determine if a novel measurement technique based on contralateral elbow radiographs, termed the RACER method, could be used to accurately estimate the magnitude of radial head implant over-lengthening. Part I of this study examined the side-to-side consistency of radiographic landmarks used in the measurement technique. Part II of this study validated the technique using simulated radial head implant over-lengthening in a cadaveric model. Method. Part I: A side-to-side comparison of elbow joint dimensions was performed in 50 patients (100 radiographs). Part II: Radial head prostheses of varying lengths (0,+2mm,+4mm,+6mm,+8mm) were implanted in 4 paired cadaveric specimens (8 elbows). Radiographs were obtained and measurements were performed by 2 examiners blinded to implant size to determine if contralateral radiographs could diagnose and provide a valid estimate of the magnitude of implant over-lengthening. Intra and inter-rater reliability was determined. Results. No significant side-to-side differences (p>0.2) in radiographic measurements were identified between paired elbows. The RACER measurement technique using contralateral radiographs was successful in predicting the implant size (1mm) in 104 of 120 (87%) of scenarios tested. The sensitivity of the technique, the ability of the test to correctly identify over-lengthening when it was present within 1mm, was 98%. The intra-rater agreement for a single orthopaedic surgeon measuring on 2 separate occasions was excellent (ICC>0.90). The inter-rater agreement between two separate surgeons was also excellent, with the 95% lower confidence interval exceeding 0.90 in all cases. Conclusion. A novel measurement technique based on contralateral elbow radiographs can be used to diagnose and calculate the magnitude of radial head implant over-lengthening. Clinical Significance: Implantation of an incorrectly sized radial head prosthesis is not uncommon. The described technique can be used to effectively diagnose and determine the magnitude of over-lengthening

Background. The quest for the perfectly designed elbow prosthesis continues as instability and loosening remain the foremost reasons for the failure of total elbow replacement (TER). The Discovery® Elbow System (Biomet, UK) (Figure 1), which has been used in UK since 2003, is one of the latest generations of linked prosthesis. This system was designed to decrease polyethylene-bushing wear, improve anatomic stem design, restore elbow joint biomechanics, and produce a hinge that could be easily revised. This report describes the short term outcome of TER using the Discovery® Elbow System. Patients and Methods. A total of 60 TERs including 48 primary and 12 revisions were performed between 2003 and 2008. Patients included 21 males (37%) and 36 females (63%) with a mean age of 63 years. The indications for primary TER were advanced rheumatoid arthritis (n=19), osteoarthritis (n=16), post traumatic osteoarthritis (n=9), acute fractures (n=3), and haemophilic arthropathy (n=1). The outcome was assessed using pain score, Liverpool Elbow Score (LES), and range of movement during a mean follow-up of 26 months. Associated complications were documented. Radiological assessment included evaluation for loosening, instability and periprosthetic fractures. Results. The mean LES was significantly (p<0.001) improved from 3.8 (±1) pre-operatively to 6.9 (±2) at the final follow- up. Significant improvements were noted in elbow flexion from 100° (±22) to 120° (±15), supination from 41° (±28) to 65° (±20) and pronation from 52° (±22) to 72° (±18). There was no significant change in elbow extension. Mean improvement in flexion-extension and pronation-supination arc was 22° and 44°, respectively. 46 cases (77%) were completely pain-free at the final follow-up. The main complications included deep infection (4 cases – treated with staged revision TER), postoperative ulnar neuropathy (3 cases–treated with decompression), intra-operative fractures of medial condyle (3 cases – treated non-operatively with brace), and elbow haemarthrosis (1 case). Discussion. TER with Discovery® Elbow System resulted in either no pain or mild pain in 87% of cases. Patients undergoing Acclaim, Souter-Strathclyde, GSB III, and Coonrad-Morrey TER have been reported to have no/mild pain in 64%, 67%, 50–92% and 60–100% of cases, respectively. A 22° improvement in flexion-extension arc is comparable to that of Acclaim (23°), Souter-Strathclyde (15°), GSB III (19–33°), and Coonrad-Morrey (17–26°) TER. An improvement of 44° in pronation-supination arc in our series is also comparable to that of 31–67° reported for GSB III and higher than the Coonrad-Morrey prosthesis (21–28°). In terms of complications, an infection rate of 6.7% is consistent with those reported for GSB III TER (7–11%) and Coonrad-Morrey (6–8%). The incidence of persistent ulnar neuropathy was lower compared to GSB III TER (11–14%), Coonrad-Morrey (12–26%), and Acclaim (8%). While the survival of Discovery TER was 93%, the survival of GSB III (5–6 years) and Coonrad-Morrey (5 years) has been reported as 71–85% and 72–90%. The results indicate that Discovery® Elbow System is an effective device for total elbow arthroplasty in terms of functional improvement, pain relief and range of motion at short-term follow-up

Purpose. Recent work has shown that joint contracture severity can be decreased with the mast cell stabilizer ketotifen in association with decreased numbers of myofibroblasts and mast cells in the joint capsule of a rabbit model of post-traumatic contractures. Neuropeptides such as Substance P (SP) can induce mast cells to release growth factors. Using a gel contraction assay, we test the hypothesis that joint capsule cell-mediated contraction of a collagen gel can be enhanced with SP, but the effect is magnified in the presence of mast cells. Method. Anterior elbow joint capsules were obtained at the time of surgical release from 2 men (age 34 and 54) and 1 woman (age 40) with chronic (> 1 year) post-traumatic joint contractures. The human mast cell line HMC-1 (Mayo Clinic, Rochester), SP and the NK1 receptor antagonist RP67580 (Sigma, Oakville, ON) were used. NK1 is the SP receptor. Neutralized Collagen solution composed with 58% Vitrogen 100 purified collagen mixed with HMC-1 cells only (7.5 105), human capsule cells (2.5 105), or human capsule cells (2.5 105) and 7.5 105 mast cells (1:3) were cast into 24- well tissue culture plates. In some experiments, SP (1 × 10. −5. M) +/− RP67580 (0.5 mM) were added. The gels were maintained with 0.5 ml DMEM composed with 2% BSA and incubated at 37C for 12 h for gelation to occur. The gels were then detached from the wall and the bottom of culture plate wells, and photographed at regular intervals up to 72 hours. Gel contraction studies were carried out on passage 4 and done in triplicate for each patient. The average value of each patients triplicate was combined to give a mean contraction at each time point. Statistical analysis involved an ANOVA with posthoc Bonferroni correction. P < 0.001 was significant. Results. Mast cells alone or with SP were unable to contract collagen gels. Joint capsule cells were able to contract the collagen gels and this was enhanced in the presence of SP, although not statistically significant. Joint capsule cells combined with mast cells enhanced the gel contraction more than joint capsule cells alone or with SP (p<0.001). The addition of SP accelerated the joint capsule cell-mediated gel contraction in the presence of mast cells the greatest (p<0.001 over all other conditions). The inhibitor RP67580 completely abolished the collagen gel contraction of the joint capsule cells in all conditions. Conclusion. The in vitro experiment shows that joint capsule cell function, in the form of collagen gel contraction, is modified by the presence of mast cells and neuropeptides. These findings are significant as they strengthen the hypothesis that a myofibroblast mast cell neuropeptide fibrosis axis may be contributing to the joint capsule changes underling the loss of motion in post-traumatic joint contractures. In vivo studies with the rabbit model of post-traumatic contractures will be performed using the compounds examined in the current study

Construction of a functional skeleton is accomplished through co-ordination of the developmental processes of chondrogenesis, osteogenesis, and synovial joint formation. Infants whose movement in utero is reduced or restricted and who subsequently suffer from joint dysplasia (including joint contractures) and thin hypo-mineralised bones, demonstrate that embryonic movement is crucial for appropriate skeletogenesis. This has been confirmed in mouse, chick, and zebrafish animal models, where reduced or eliminated movement consistently yields similar malformations and which provide the possibility of experimentation to uncover the precise disturbances and the mechanisms by which movement impacts molecular regulation. Molecular genetic studies have shown the important roles played by cell communication signalling pathways, namely Wnt, Hedgehog, and transforming growth factor-beta/bone morphogenetic protein. These pathways regulate cell behaviours such as proliferation and differentiation to control maturation of the skeletal elements, and are affected when movement is altered. Cell contacts to the extra-cellular matrix as well as the cytoskeleton offer a means of mechanotransduction which could integrate mechanical cues with genetic regulation. Indeed, expression of cytoskeletal genes has been shown to be affected by immobilisation. In addition to furthering our understanding of a fundamental aspect of cell control and differentiation during development, research in this area is applicable to the engineering of stable skeletal tissues from stem cells, which relies on an understanding of developmental mechanisms including genetic and physical criteria. A deeper understanding of how movement affects skeletogenesis therefore has broader implications for regenerative therapeutics for injury or disease, as well as for optimisation of physical therapy regimes for individuals affected by skeletal abnormalities.

Cite this article: Bone Joint Res 2015;4:105–116