Introduction. Cervical orthoses are commonly used to regulate the motion of cervical spines for conservative treatment of injuries and for post-operative immobilization. Previous studies have reported the efficacy of orthoses for 2D flex-extension or 3D motions of the entire cervical spine. However, the ability of cervical orthoses to reduce motion might be different at each intervertebral level and for different types of motion (flexion-extension, rotation, lateral bending). The effectiveness of immobilizing orthoses at each cervical intervertebral level for 3D motions has not been reported. The purpose of this study is to evaluate the effectiveness of the Philadelphia collar to each level of cervical spines with 3D motion analysis under loading condition. Patients & Methods. Patient Sample Four asymptomatic volunteer subjects were recruited and provided informed consent. Approval of the experimental design by the institutional review board was obtained. These 4 individuals were without any history of cervical diseases or procedures. The presence of any symptoms, spinal disorders and anatomical abnormalities in fluoroscopic images or CT was a criterion of exclusion from this study. Outcome Measures To evaluate the efficacy of the Philadelphia collar, ANOVA was used to compare the range of motion with and without collar at the C3/4, C4/5, C5/6 and C6/7 intervertebral levels for each motion. The level of statistical significance was set at p < 0.05. When a statistical difference was detected, post hoc Tukey tests were performed. Methods. Three-dimensional models of the C3–C7 vertebrae were developed from CT scans of each subject using commercial software (see Figure 1). Two fluoroscopy systems were positioned to acquire orthogonal images of the cervical spine. The subject was seated within the view of the dual fluoroscopic imaging system (see Figure 2). Pairs of images were taken in each of 7 positions: neutral posture, maximum flexion and extension, maximum left and right lateral bending, and maximum left and right rotation. The images and 3D vertebral models were imported into biplane 2D-3D registration software, where the vertebral models were projected onto the pair of digitized images and the 3D bone pose was adjusted to match its radiographic projection in each image (see Figure 3). Relative motions between each vertebral body were calculated from body-fixed coordinate systems using a flexion-lateral bending-axial rotation Cardan angle sequence. Results. Flexion range was significantly reduced with the collar at each cervical level. Extension range was significantly reduced at the C3/4 level. Rotation and lateral bending were reduced for C3/4, C4/5, C5/6 levels with the collar. Discussion/Conclusion. The Philadelphia Collar significantly reduces cervical motion at C3/4, C4/5 and C5/6 levels in almost all motions (except for extension). At the C6/7 level, this type of collar has limited effectiveness reducing cervical motion. We used 3D radiographic measurements to quantify the effectiveness of the Philadelphia collar for reducing cervical motion. Bi-plane 2D-3D registration method is useful technique to evaluate 3D motion of cervical spines

Introduction. Aseptic loosening is the most common mode of failure of massive endoprostheses. Introduction of Hydroxyapatite coated collars have reduced the incidence of aseptic loosening. However bone growth is not always seen on these collars. Objectives. The aims of our study were to determine the extent of osseous integration of Hydroxyapatite coated collars, attempt a grading system for bone growth and to determine the effect of diagnosis, surgical technique and adjuvant therapy on bone growth. Methods. We reviewed the records and radiographs of 58 patients who had a massive endoprosthesis implanted by two surgeons in our unit over the last five years. Revision surgeries were recorded separately. Bone growth was graded 1–4 based on appearance in antero-posterior and lateral radiographs. Results. Three groups were identified. Group 1-Resections for primary bone tumours (33 patients), Group 2-resections for metastatic bone disease (22 patients) and Group 3- Resections for non tumour indications (3 patients). Overall, 60% of patients had grade 1, 12% had grade 2, 19% had grade 3 and 9% had grade 4 osteointegration. Grade 3 or 4 Collar osteointegration was found in 37% of patients in Group 1, 9% in group 2 and 67% in group 3. 5% of patients with grade 1 integration, 100% patients with grade 2 integration and none of the patients with grade 3 or 4 integration underwent revision for aseptic loosening. Appearance or widening of a gap between the resected bone end and the collar indicated loosening and impending revision. Proximal humeral replacements had the lowest rate of osteointegration (12%). Adjuvant therapy did not affect osteointegration. Conclusion. Osteointegration of collars is seen more often after resection of primary bone tumours. The role of collars in metastatic tumour surgery is questionable. Our radiographic grading system of bone growth predicted aseptic loosening

Introduction. The value of collared stems for uncemented implants remains controversial. Some comparative studies have demonstrated advantages of collared stems regarding the potential for subsidence. Other studies with longer follow-up have shown no adverse effect of the use of a collar regarding the femoral component survivorship. To date, the adequate size of the collar with regards to the anatomy of the proximal femur has never been studied. The goal of this study was to assess whether the size of the collar needs to be adjusted according to the size of the femoral component used, and according to the use of a standard or a lateralized component. Materials and Method. 102 CT of normal femurs have been divided into 2 groups of 51 femurs each. Each group has been analysed by 2 independant surgeons. Each CT view passed through the axis of the proximal diaphysis and the center of the femoral head. The scale was 100%. Templates of femoral components have been set in order to reproduce the center of rotation and an optimal filling of the proximal femoral canal. Sizes of the femoral components as well as the need for standard or lateralized implants have been recorded. In order to determine the ideal size of the collar, the distance between the medial edge of the prothesis and the medial edge of the femur (so-called P-C distance) at the level of the neck cut (calcar) has been measured. Results. The inter-observer concordance for the selection of the implant type (i.e. standard or lateralized), size, and P-C distance measurement was satisfactory (kappa 0.7). 56% of the selected implants were standard. The mean size was 5 (1 to 10). The mean P-C distance was 9.9mm (5 to 16mm). It was 8.8mm for standard implants and 11.3mm for lateralized implants, with significant difference (p<0.0001). The size of the selected implant was significantly related to the P-C distance (r=0.27; p<0.005). Conclusion. These results suggest that the size of the collar should increase with larger sizes, and that the use of a longer collar with lateralized implants should be advocated

Cervical spine collars are applied in trauma situations to immobilise patients' cervical spines. Whilst movement of the cervical spine following the application of a collar has been well documented, the movement in the cervical spine during the application of a collar has not been. There is universal agreement that C-spine collars should be applied to patients involved in high speed trauma, but there is no consensus as to the best method of application. The clinical authors have been shown two different techniques on how to apply the C-spine collars in their Advanced Life Support Training (ATLS). One technique is the same as that recommended by the Laerdal Company (Laerdal Medical Ltd, Kent) that manufactures the cervical spine collar that we looked at. The other technique was refined by a Neurosurgeon with an interest in pre-hospital care. In both techniques the subjects' head is immobilised by an assistant whilst the collar is applied. We aimed to quantify which of these techniques caused the least movement to the cervical spine. There is no evidence in the literature quantifying how much movement in any plane in the unstable cervical spine is safe. Therefore, we worked on the principle: the less movement the better. The Qualisys Motion Capture System (Qualisys AB, Gothenburg, Sweden) was used to create an environment that would measure movement on the neck during collar application. This system consisted of cameras that were pre-positioned in a set order determined by trial and error initially. These cameras captured reflected infra-red light from markers placed on anatomically defined points on the subject's body. As the position of the cameras was fixed then as the patients moved the markers through space, a software package could deduce the relative movement of the markers to each camera with 6 degrees of freedom (6DOF). Six healthy volunteers (3 M, 3 F; age 21-29) with no prior neck injuries acted as subjects. The collar was always applied by the same person. Each technique was used 3 times on each subject. To replicate the clinical situation another volunteer would hold the head for each test. The movements we measured were along the x, y, and z axes, thus acting as an approximation to flexion, extension and rotation occurring at the C-spine during collar application. The average movement in each axis (x, y and z) was 8 degrees, 8 degrees and 5 degrees respectively for both techniques. No further data analysis was attempted on this small data set. However this pilot study shows that our method enables researchers to reproducibly collect data about cervical spine movement whilst applying a cervical collar

Increasing pressure to use rapid recovery care pathways when treating patients undergoing total hip arthroplasty (THA) is evident in current health care systems for numerous reasons. Patient autonomy and health care economics has challenged the ability of THA implants to maintain functional integrity before achieving bony union. Although collared stems have been shown to provide improved axial stability, it is unclear if this stability correlates with activity levels or results in improved early function to patients compared to collarless stems. This study aims to examine the role of implant design on patient activity and implant fixation. The early follow-up period was examined as the majority of variation between implants is expected during this time-frame. Patients (n=100) with unilateral hip OA who were undergoing primary THA surgery were recruited pre-operatively to participate in this prospective randomized controlled trial. All patients were randomized to receive either a collared (n=50) or collarless (n=50) cementless femoral stem. Patients will be seen at nine appointments (pre-operative, < 2 4 hours post-operation, two-, four-, six-weeks, three-, six-months, one-, and two-years). Patients completed an instrumented timed up-and-go (TUG) test using wearable sensors at each visit, excluding the day of their surgery. Participants logged their steps using Fitbit activity trackers and a seven-day average prior to each visit was recorded. Patients also underwent supine radiostereometric analysis (RSA) imaging < 2 4 hours post-operation prior to leaving the hospital, and at all follow-up appointments. Nineteen collared stem patients and 20 collarless stem patients have been assessed. There were no demographic differences between groups. From < 2 4 hours to two weeks the collared implant subsided 0.90 ± 1.20 mm and the collarless implant subsided 3.32 ± 3.10 mm (p=0.014). From two weeks to three months the collared implant subsided 0.65 ± 1.54 mm and the collarless implant subsided 0.45 ± 0.52 mm (p=0.673). Subsidence following two weeks was lower than prior to two weeks in the collarless group (p=0.02) but not different in the collared group. Step count was reduced at two weeks compared to pre-operatively by 4078 ± 2959 steps for collared patients and 4282 ± 3187 steps for collarless patients (p=0.872). Step count increased from two weeks to three months by 6652 ± 4822 steps for collared patients and 4557 ± 2636 steps for collarless patients (p=0.289). TUG test time was increased at two weeks compared to pre-operatively by 4.71 ± 5.13 s for collared patients and 6.54 ± 10.18 s for collarless patients (p=0.551). TUG test time decreased from two weeks to three months by 7.21 ± 5.56 s for collared patients and 8.38 ± 7.20 s for collarless patients (p=0.685). There was no correlation between subsidence and step count or TUG test time. Collared implants subsided less in the first two weeks compared to collarless implants but subsequent subsidence after two weeks was not significantly different. The presence of a collar on the stem did not affect patient activity and function and these factors were not correlated to subsidence, suggesting that initial fixation is instead primarily related to implant design

Background. There is increasing impetus to use rapid recovery care pathways when treating patients undergoing total hip arthroplasty (THA). The direct anterior (DA) approach is a muscle sparing technique that is believed to support these new pathways. Implants designed for these approaches are available in both collared and collarless variations and understanding the impact each has is important for providing the best treatment to patients. Purpose/Aim of Study. This study aims to examine the role of implant design on implant fixation and patient recovery. Materials and Methods. Patients (n=50) with unilateral hip OA who were undergoing primary DA THA surgery were recruited pre-operatively to participate in this prospective randomized controlled trial. All patients were randomized to receive either a collared (n=25) or collarless (n=25) cementless, fully hydroxyapatite coated femoral stem. Patients were seen at nine appointments (pre-operative, <24 hours post-operation, two-, four-, six-weeks, three-, six-months, one-, and two-years). Patients underwent supine radiostereometric analysis (RSA) imaging <24 hours post-operation prior to leaving the hospital, and at all follow-up appointments. Patients also completed an instrumented timed up-and-go (TUG) test using wearable sensors at each visit, excluding the day of their surgery. Participants logged their steps using Fitbit activity trackers and a seven-day average prior to each visit was recorded. Findings/Results. Twenty-two patients that received a collared stem and 27 patients that received a collarless stem have been assessed. There were no demographic differences between groups. From <24 hours to two weeks the collared implants subsided 0.90 ± 1.20 mm and the collarless implants subsided 3.80 ± 3.37 mm (p=0.001). From two weeks to three months the collared implants subsided 0.67 ± 1.61 mm and the collarless implants subsided 0.45 ± 0.46 mm (p=0.377). Step count was reduced at two weeks to 3108 ± 1388 steps for collared patients and 2340 ± 1685 steps for collarless patients (p=0.072). Step count was increased at three months to 8939 ± 3494 steps for collared patients and 6114 ± 2529 steps for collarless patients (p=0.034). TUG test time was increased at two weeks compared to pre-operatively by 3.45 ± 6.01 s for collared patients and 2.29 ± 4.92 s for collarless patients (p=0.754). TUG test time decreased from two weeks to three months by 6.30 ± 6.05 s for collared patients and 5.68 ± 4.68 s for collarless patients (p=0.922). Conclusions. Collared implants subsided less in the first two weeks compared to collarless implants but subsequent subsidence after two weeks was not significantly different. Presence of a collar on the stem impacted patient activity but not function. This suggests that both the implant design as well as the surgical technique may play a role in the patient's early post-operative experience

Introduction. Primary stability is essential for long-term performance of cementless femoral components. There is debate as to whether collars contribute to primary stability. The results from experimental studies and finite element (FE) analysis have been variable and contradictory. Subtle differences in performance are often swamped by variation between cadaveric specimens in vitro, whereas FE studies tend to be performed on a single femur. However, FE studies have the potential to make comparisons of implant designs within the same cohort of femurs, allowing for subtle performance differences to be identified if present. This study investigates the effect of a collar on primary stability of a femoral prosthesis across a representative cohort of femurs. Materials and Methods. FE models were generated from QCT scans of eight cadaveric femurs taken from the Melbourne Femur Collection (4 male and 4 female; BMI: 18.7 – 36.8 kg.m-2; age: 59 – 80 years) which were of joint replacement age. Heterogeneous bone material properties were assigned based on the CT greyscale information. Each femur was implanted with the collared and collarless version of Corail femoral stem (DePuy, Leeds, United Kingdom). The stems were sized and positioned so that the prosthesis filled the medullary canal with minimal gap between the prosthesis and the inner boundary of the cortical bone. The peak muscle and joint contact forces associated with level gait were applied and the distal femur was rigidly fixed. The forces were scaled based on the body weight for each subject. Micromotion, as well as microstrains at the bone-prosthesis interface were measured for each subject. Paired t-test was run to compare the micromotion and the microstrains measured for the collared and collarless prosthesis. Results. There were no significant differences in micromotion (p > 0.005) and microstrains (p » 0.005) between collared and collarless prostheses. The mean of the median micromotions for the collared and the collarless prostheses were 19.4 microns and 20.5 microns, respectively. The mean of the median equivalent strains at the bone-implant interface for the collared and the collarless prostheses were 828.5 microstrains and 824.3 microstrains, respectively. The mean percentage of the area at the contact interface that experienced equivalent strains lower than 2000 microstrains was 69.9% for the collared and 70.0% for the collarless designs. The mean percentage of the contact area at the bone-prosthesis interface that experience equivalent strains greater than 7000 microstrains, the yield strain, was only 9.9% for the collared and 5.7% for the collarless designs. Discussion and conclusions. There was considerable variation across the cohort of femurs, with a factor of two difference for both micromotion and interface strain While small differences were noted between the collared and collarless prostheses implanted in the same femur, these differences were minimal and were likely to have little affects on primary stability, at least for a level gait load case. More demanding load cases may result in greater differences between collared and collarless implants. The results suggest that the addition of a collar in routine cases may not enhance the primary stability of a cementless hip stem

Introduction:. Distal femoral replacement is recognised as the optimum treatment for malignant distal femoral tumours. Aseptic loosening is known to be a major cause for failure in these implants. Studies have indicated that the HA coated collar promotes osteointegration and bony in growth. This study compares long term aseptic loosening in implants with HA coated collars to those without in the immature skeleton. Objectives:. To assess the effect of HA coated collars on aseptic loosening in extendable distal femoral replacement prosthesis in the immature skeleton. Methods:. All paediatric patients undergoing distal femoral replacement with extendable prosthesis were retrospectively reviewed between 1980–2003. A total of 32 patients were reviewed. 24 patients underwent distal femoral replacement with extendable prostheses without a HA coated collar. This cohort was compared to 18 patients who were treated with an extendable prosthesis with a HA coated collar between 2001–03. Average follow up in patients without a collar was 10.1 yrs (6–18) and 8.1 yrs in those with a collar (4–11). All patients with identified infection were excluded. Radiographs taken at last follow-up were analysed for loosening. Results:. Thirty-one patients were treated for primary osteosarcoma and one for a histiocytoma. Average age at operation was 13 yrs for both groups (non-collared 6–17, collared 4–11). Three of 24 patients in the non-collared cohort underwent revision compared to 1 of 18 in the collared group. The cause of revision in the collared group was infection. One patient in each cohort died within 5 years of surgery. Mean loosening score at last follow up for the non-collared group was 11.2 compared to 2.5 for the collared group with a p value of <0.05 (Mann Whitney-U). Conclusions:. Aseptic loosening is a major cause of failure for distal femoral replacement prosthesis. HA coated collars have been shown to promote osteointegration. Little comparable data exists between collared and non-collared extendable prosthesis in the immature skeleton. Our data demonstrates that HA coated collars significantly reduce long term loosening in the immature skeleton

The aim of the study was to highlight the absence of an important pitfall in the Advanced Trauma Life Support protocol in application of rigid collar to patients with potentially unstable cervical spine injury. We present a case series of two patients with ankylosed cervical spines who developed neurological complications following application of rigid collar for cervical spine injuries as per the ATLS protocol. This has been followed up with a survey of A&E and T&O doctors who regularly apply cervical collars for suspected unstable cervical spine injuries. The survey was conducted telephonically using a standard questionnaire. 75 doctors completed the questionnaire. A&E doctors = 42, T&O = 33. Junior grade = 38, middle grade = 37. Trauma management frontline experience >1yr = 50, <1yr = 25. Of the 75 respondents 68/75 (90.6%) would follow the ATLS protocol in applying rigid collar in potentially unstable cervical spine injuries. 58/75 (77.3%) would clinically assess the patient prior to applying collar. Only 43/75 (57.3%) thought the patients relevant past medical history would influence collar application. Respondents were asked whether they were aware of any pitfalls to rigid collar application in suspected neck injuries. 34/75 (45.3%) stated that they were NOT aware of pitfalls. The lack of awareness was even higher 17/25 (68%) amongst doctors with less that 12 months frontline experience. When directly asked whether ankylosing spondylitis should be regarded as a pitfall then only 43/75 (57.3%) answered in the affirmative. We would like to emphasise the disastrous consequences of applying a rigid collar in patients with ankylosed cervical spine. The survey demonstrates the lack of awareness (∼ 50%) amongst A&E and T&O doctors regarding pitfalls to collar application. We recommend the ATLS manual highlight a pitfall for application of rigid collars in patients with ankylosed spines and suspected cervical spine injuries

Background. Endoprosthetic reconstruction is an established method of treatment for primary bone tumours in children. Traditionally these were implanted with cemented intramedullary fixation. Hydroxyapatite collars at the shoulder of the implant are now standard on all extremity endoprostheses, but older cases were implanted without collars. Uncemented intramedullary fixation with hydroxyapatite collars has also been used in an attempt to reduce the incidence of problems such as aseptic loosening. Currently there are various indications that dictate which method is used. Aims. To establish long term survivorship of cemented versus uncemented endoprosthesis in paediatric patients with primary bone tumours. Methods. This was a retrospective study of 441 endoprostheses implanted in 367 consecutive patients aged 18 years or less, between 1973 and 2005. This included the use of case notes, hospital databases and a radiological review. Information obtained included patient demographics, indications for surgery, anatomical distribution and type of implants, complications and survivorship. Results. Mean age was 13.9 (range 3 - 38). 210 patients were male, 157 were female. There were 364 primaries and 77 revision implants. 161 extendable and 280 definitive prostheses. 282 patients had osteosarcoma, 54 had Ewing's sarcoma and 28 had other diagnoses. Commonest sites included 197 distal femoral replacements, 85 proximal tibial implants and 57 were in the upper limb. Kaplan-Meier survival analysis was used to compare anatomical sites and method of fixation. Upper limb implants had the best long term survival. Failure rates for distal femoral replacements were compared for cemented fixation (21.7% due to aseptic loosening) with cement plus hydroxyapatite collars (3.1%) and uncemented implants with hydroxyapatite collars (6.2%). Conclusions. In the distal femur cemented fixation with hydroxyapatite collars gave the best survivorship in definitive primary prostheses. Uncemented fixation with hydroxyapatite collars gave the best survivorship in extendable prostheses. Cemented fixation without hydroxyapatite gave the worst survivorship

Despite the publication of numerous studies, controversy regarding the non- operative treatment of type II dens fractures remains. The halo-thoracic vest (HTV) and cervical collar are the most commonly used devices. We sought to compare the outcomes of patients managed with these devices in terms of non-union risk factors and associated complication rates. This study was a retrospective review of adult patients with type II dens fractures treated non-operatively at a level one trauma centre between 2001 and 2007. The patients were identified using a hospital trauma database. Each patient included in the study had a minimum follow up of six months. Patient medical records and imaging studies were reviewed. Union was defined as stable fibrous union or bony union, measured at three months. A p-value of < 0.05 was considered statistically significant. Sixty-seven patients were included. Thirty-five patients were treated using a HTV and 32 with a collar. Non-union was found to be associated with increased time in HTV or collar (p = 0.011) and with a mechanism of injury involving a low fall (p = 0.008). In addition, the proportion of patients with stable union at three months was 60% for the HVT group versus 35% for the cervical collar group (p = 0.10). There were trends to support an increased risk of non-union with a patient age of greater than or equal to 65 years at the time of presentation (p = 0.13) as well as with a fracture displacement of greater than or equal to 2 mm at time of presentation (p = 0.17). Clinically significant complications of the HTV were of greater prevalence than those experienced by collar patients. Sixty percent of HTV patients suffered one or more complications compared with 6% of collar patients. We were unable to demonstrate any clear advantage or disadvantage of either device. Further investigation of mortality would be beneficial, particularly in the patient group injured with a mechanism involving a low fall (which tends to include more elderly patients)

Introduction. The French paradox regarding cemented femoral components has not been resolved, so we compared the mechanical behavior of a French stem, the CMK stem (Biomet, Warsaw, IN, USA), with a collarless, polished, tapered stem (CPT, Zimmer, Warsaw, IN, USA) using an original biomechanical instrument. Materials and Methods. Two size-3 CPT stems and two size-302 CMK stems stems were fixed with bone cement into a composite femur soaked in vegetable oil to simulate wet condition. The composite femur was attached to a biomechanical testing instrument after stem implantation, and a 1-Hz dynamic sine wave load (3000 N) was applied to the stems for a total of 1 million cycles. An 8-hour unload period was set after every 16 hours of load. Femur temperature was maintained at 37°C during testing. The femoral canal was prepared for the CPT stems by standard rasping; for the CMK stems, however, the French method was used, in which cancellous bone was removed with a reamer. One CMK stem (CMK-1) was inserted into a femur without collar contact (>2 mm above the calcar), and the other (CMK-2) was inserted into a femur with collar contact. Stem subsidence was measured at the stem shoulder. Compressive force and horizontal cement movement were measured via rods set at the cement–bone interface on the medial, lateral, anterior, and posterior sides of the proximal and distal portions of the composite femurs. Results. Subsidence was as follows: 0.521 mm and 0.629 mm for the CPT stems, 0.46 mm for CMK-1, and 0.36 mm for CMK-2. Compressive force at the cement–bone interface was at the maximum level at the proximomedial portion of all stems. These forces increased gradually until the one-millionth loading. Maximum compressive forces were 183 N and 107 N for the CPT stems, 180 N for CMK-1, and 215 N for CMK-2. There was a strong positive correlation between stem subsidence and compressive force in all stems. Radial cement creep at the proximomedial portion was 90 μ for one of the CPT stems, 184 μ for CMK-1, and −636 μ for CMK-2. Discussion. We previously reported our findings of a positive correlation between stem subsidence and compressive force in CPT stems. In the current study, CMK stems also subsided even when there was stem collar contact with bone. Subsidence was less in CMK stems than in CPT stems, but the values were close. In addition, compressive force and radial cement creep in CMK stems were also similar to or greater than in CPT stems. Conclusion. The two different concept stems demonstrated similar behavior in relation to bone cement, a finding that may present a solution to the French paradox

The International Commission on Radiological Protection has established standards for radiation protection. This study aims to determine actual and perceived radiation dose and audit safe practice when using image-intensifiers in theatre. Between September 2012 and March 2013, 50 surgeons were surveyed during 39 procedures. Information collected by radiographers included the number of images the surgeons thought they used, actual number used, dose, screening time, number of people scrubbed, wearing thyroid collars and standing within 1m of the image-intensifier when in use. The primary surgeon was more likely to estimate the number of images used correctly compared to the assistant. Supervising consultants were most accurate, followed by registrars as primary surgeons, consultants as primary surgeons then assisting registrars, and lastly SHOs. Most surgeons underestimated the number of images used. 87.5% of scrubbed staff were standing within 1m of the image-intensifier during screening and 36.5% were wearing thyroid protection. Three surgeons stated they were not wearing collars as they were unavailable. We conclude that surgeons have a reasonable estimation of the x-rays used but are not undertaking simple steps to protect themselves from radiation. We plan to initiate an education program within the department and have ordered new, lightweight thyroid collars

Introduction. This study was performed to investigate the failure mechanism of one specific hip arthroplasty cup design that has shown a high clinical failure rate. The aim of this study was to identify general design problems of this polyethylene inlay. Material and Methods. 55 consecutive retrievals of a cementless screw ring (Mecron) were collected. In any case a 32 mm ceramic head was used. All implants failed due to aseptic loosening. The follow-up of the implants was 3 to 16 years. We recorded backside wear, fatigue of the polyethylene at the flanges on the outer rim and at the cup opening (32 mm inner diameter). To assess the deformation of the inlay, the smallest and the median diameter of the cup opening were measured using a 3 dimensional coordinate measuring machine (Multisensor, Mahr, Germany). Results. 90% of the explants showed signs of wear on the backside of the inlay. Another typical and so far not described alteration was collar fatigue in 68%. 38% of the inlays showed rim creep: Examples for Backside wear, collar fatigue and rim creep are illustrated in Fig. 1. 90% had a diameter of 32.1 mm or less, and even 46% had a diameter less than 32 mm. Discussion. The investigated design is at the lower limit of the allowed machining tolerance of the cup opening (32 + 0.1 mm) and has no additional clearance (which some manufacturers add). It seems that the inlays yield at the dome because of the viscoelastic properties of polyethylene and the open dome area of the attached screw ring. This leads to excessive wear at the dome area and it triggers a “brake drum” effect at the cup opening. Thereby torsional stresses at the implant bone interface increase which lead to failure of the implant. To avoid this type of failure, PE inlays should have enough clearance at the cup opening and the inlay should have dome contact to the closed metal shell

Revision of the humeral component in shoulder arthroplasty is frequently necessary during revision surgery. Newer devices have been developed that allow for easy extraction or conversion at the time of revision preserving bone stock and simplifying the procedure. However, early generation anatomic and reverse humeral stems were frequently cemented into place. Monoblock or fixed collar stems make accessing the canal from above challenging. The cortex of the Humerus is far thinner than the femur and stress shielding has commonly led to osteopenia. Many stem designs have fins that project into the tuberosities putting them at risk for fracture on extraction. Extraction starts with an extended deltopectoral incision from the clavicle to the deltoid insertion. The proximal humerus needs to be freed from adhesions of the deltoid and conjoined tendon. The deltopectoral interval is fully developed. Complete subscapularis and anterior capsular release to the level of the latissimus tendon permits full exposure of the humeral head. After head removal the stem can be assessed for loosening and signs of periprosthetic joint infection. The proximal bone around the fin of the implant should be removed from the canal. If possible, the manufacturer's extractor should be utilised. If not, then a blunt impactor can be placed from below against the collar of the stem to assist in extraction. With luck the stem can be extracted from the cement mantle. If there is no concern for infection, the cement-in-cement technique can be used for revision. Otherwise, attempts should be made to extract all the cement and cement restrictor, if present. The small cement removal tools from the hip set can be used and specialised shoulder tools are available. An ultrasound cement removal device can be very helpful. The surgeon must be particularly careful to avoid perforation of the humeral cortex. This is especially important when near the radial nerve as injury can occur. When a well-fixed stem is encountered, an osteotomy of the proximal humerus is necessary. The surgeon can utilise a linear cut with an oscillating saw along the bicipital groove for the length of the implant. An osteotome is used to crack the cement mantle allowing stem extraction. Alternatively, a window can be created to offer additional access to the cement mantle. In the event the surgeon has required an osteotomy or window, cerclage wires, cables or suture will be needed and when the bone is potentially compromised, allograft bone graft struts (tibial shaft) are used for additional support. Care is needed when passing cerclage wires to avoid injury to the radial nerve which is adjacent to the deltoid insertion. If infection is suspected or confirmed an ALBC spacer is placed. When single stage revision is planned both cemented and uncemented stem options are available. Cement placed around the humeral stem has been suggested to decrease infection incidence. Revision of cemented humeral stems is a continued challenge in revision shoulder surgery. Newer systems and reverse total shoulder options have improved the surgeon's ability to achieve good outcomes when revising prior shoulder arthroplasty

Introduction. The orthopaedic market offers more than two hundred different hip femoral stems. Of these, very few have undergone scientific studies with published results. The differences of designs of the stem are mainly related to surface texture and geometry sections. The development of a new cemented hip prosthesis is certainly a very hard task if aiming the improvement of actual performance. Materials and Methods. This study presents the influence of geometric variables in a novel hip stem concept which was based on the comparison of the performance of the best cemented stems actually in the market. The study was developed using finite element analysis and experiments with in vitro femoral replacements. A numerical simplified model of the hip replacement was designed to generate the final geometry of the femoral stem section. After an in vitro cemented commercial stem was done, with the best cemented stem a Lubinus, Charnley, Stanmore and Müller. Realistic numerical models also allowed us to determine cement mantle stresses of commercial femoral stems that were compared with those obtained for the new concept stem. The new model was then prototyped and tested through in vitro fatigue tests. Finally fatigue tests were also performed to determine the density of cracks in the cement mantles, as well as debonding for both conventional and new designs. Results. Stem section geometry influences the fatigue mechanism at the stem–cement interface and is an important factor in the load transfer. The organic section presents 60% (average) less cement stress than sharp sections. Concerning the new stem, detail design geometry parameters were analyzed, such as collar position and orientation, medial radius and geometry of the stem tip. The simulations performed show that the new stem design presents 98.5% of cement volume under an equivalent stress lower than 3 MPa [FIG 1]. The correlation factor between this percentage with the clinical follow up results for 10 years of commercial stems is 0.964, being p=0.641 the significance level of one tailed Person correlation. Discussion. The variables associated to the stem geometry presents influence in the cement mantle stress and could improve the success. The section of stem is an important factor to improve the load transfer. The [FIG. 2] presents a resume of some variables in a new concept. The inclination of collar 5° at sagital plane reduces the stress in 10% proximally. The tip geometry influences the stress in cement and improves the femoral position. The tip geometry could reduce 20% of cement stress in distal region. Conclusions. The new femoral design was based on the findings of the finite element analysis and fatigue tests. It presents an innovative collar, “organic” geometry sections and a geometry tip that minimizes stress concentration. The stem developed reduces the cement stresses in an average of 25% relatively to the commercial stems used in the study. The work demonstrates in a new hip concept that small details in design of cemented hip may have consequences in the implant success

The axis is anatomically, developmentally and biomechanically unique from the five lower cervical vertebrae as well as the axis above it. The pars interarticularis is a transitional structure and a thin tube of cortical bone with small amount of cancellous bone. The canal-to-cord ratio is extremely large, hence the minimal risk of neurological deficit after injury. Objective:. To report long-term, minimum 5 years, clinical and radiological outcome of our series of patients with traumatic spondylolysthesis of the axis managed non-operatively. Method and material:. Thirty patients had traumatic spondylolysthesis of the axis over a period of five years (January 2005 to December 2010). There were 22 males and eight females with an average age of 36 years. Plain X-rays and CT scans were obtained to evaluate the injury. All patients were managed non-operatively. Results:. The majority (90%) of the fractures were Type I and type II traumatic spondylolistheses of the axis. The fractures were managed with Philadelphia collars and soft collars. All fractures healed uneventfully. The union rate approached 100%. Patients had excellent range of neck movements. Less than one percent of the patient had a type III traumatic spondylolysthesis of the axis with unifacet dislocation. None of them had neurological fallout. Conclusion:. Most patients with these injuries can be treated nonoperatively and heal well. It is uncommon for these patients to have neurological deficits. The only absolute indication for operative treatment is the small group with type III traumatic spondylolysthesis associated with bilateral facet dislocation

Aims

The use of fluoroscopy in orthopaedic surgery creates risk of radiation exposure to surgeons. Appropriate personal protective equipment (PPE) can help mitigate this. The primary aim of this study was to assess if current radiation protection in orthopaedic trauma is safe. The secondary aims were to describe normative data of radiation exposure during common orthopaedic procedures, evaluate ways to improve any deficits in protection, and validate the use of electronic personal dosimeters (EPDs) in assessing radiation dose in orthopaedic surgery.

Introduction. We have investigated middle-term clinical results of total hip arthroplasty (THA) cemented socket with improved technique using hydroxyapatite (HA) granules. IBBC (interfacial bioactive bone cement method, Oonishi) (1) is an excellent technique for augmenting cement-bone fixation in the long term. However, the technique is difficult and there are concerns over some points, such as bleeding control, disturbance of cement intrusion to anchoring holes by granules, difficulty of the uniform granular dispersion to the acetabular bone. To improve the original technique, we have modified IBBC (M-IBBC), and investigated the middle-term clinical results and radiographic changes. Materials and Methods. K-MAX HS-3 THA (Kyocera, Japan), with tapered cemented stem with small collar and all polyethylene cemented socket, was used for THA implants (Fig.1). Basically the third generation cementing technique was used for THA using bone cement. The socket fixation was performed with bone cement (Endurance, DePuy) and HA granules (Ca10(PO4)6(OH)2, Boneceram P; G-2, 0.3–0.6mm in size, Olympus, Japan) (Fig.2). In original IBBC technique, HA granules were dispersed on reamed acetabulum before cementing. In M-IBBC technique, HA granules were attached to bone cement on plastic plate, then inserted to reamed acetabulum and pressurized (Fig.3). 112 hip joints (95 cases) were operated between June 2010 and March 2014, and followed. The average follow-up period was 6.5 years, and average age at operation was 66.5 years. The clinical results were evaluated by Japan Orthopaedic Association Hip Score (JOA score), and X-p findings were evaluated using antero-posterior radiographs. The locations of radiolucent lines were identified according to the zones described by Delee and Charnley for acetabular components, and Zone 1 was divided into two parts, outer Zone 1a and inner Zone 1b. Results and Discussion. Revision was not performed. JOA score improved from 47 to 88. Socket and stem loosening was not observed. X-p findings of sockets demonstrated radiolucent line in Zone 1a/1b/2/3 in 0.9/0/0/0% immediately after the operation, 6.3/1.8/0/0.9% at 2 years postoperatively. After 2 years there was no progressive change, however, improvement of radiolucent line in Zone 1a was observed in two cases after 3 years postoperatively. Accordingly, at 5 years radiolucent line in Zone 1a/1b was observed in 4.4/1.8%. Oonish has reported excellent clinical results of THA with IBBC (1). To easily perform IBBC, we have modified the technique, improving the problems of IBBC. In this study, radiolucent line was observed at the margin of the socket in a small number of cases, and there was no progressive change. In addition, improvement of radiolucent line was observed in M-IBBC in this study, which was not observed in conventional cementing technique. Conclusions. It is demonstrated that M-IBBC provides stable socket cement fixation for THA. The interesting finding in M-IBBC cases was the improvement of radiolucent line, suggesting osteoconductive property of hydroxyapatite granules at the interface after the operations. The promising long-term clinical results of M-IBBC method, were expected. For any figures or tables, please contact the authors directly

We have investigated whether improvements in design have altered the outcome for patients undergoing endoprosthetic replacement of the distal femur following tumour resection. Survival of the implant and ‘servicing’ procedures have been documented using a prospective database and review of the implant design records and case records. A total of 335 patients underwent a distal femoral replacement with 162 having a fixed hinge design and 173 a rotating hinge with most of the latter group having a hydroxyapatite collar at the bone prosthesis junction. The median age of the patients was 24 years (range 13-82 yrs). With a minimum follow up of 5 years and a maximum of 30 years, 192 patients remain alive with a median follow-up of 11 years. The risk of revision for any reason was 17% at 5 years, 34% at 10 years and 58% at 20 years. One in ten patients developed an infection and 42% of these patients eventually required an amputation. Aseptic loosening was the most common reason for revision in the fixed hinge knees whilst infection and stem fracture were the most common reason in the rotating hinges. The risk of revision for aseptic loosening in the fixed hinges was 32% at ten years compared with nil for the rotating hinge knees with a hydroxyapatite collar. The overall risk of revision for any reason was halved by use of the rotating hinge, and for patients older than 40 years at time of implant. Conclusion. Improvements in design of distal femoral replacements have significantly decreased the risk of revision surgery. Infection remains a serious problem for these patients