Novel immersive virtual reality (IVR) technologies are revolutionizing medical education. Virtual anatomy education using head-mounted displays allows users to interact with virtual anatomical objects, move within the virtual rooms, and interact with other virtual users. While IVR has been shown to be more effective than textbook learning and 3D computer models presented in 2D screens, the effectiveness of IVR compared to cadaveric models in anatomy education is currently unknown. In this study, we aim to compare the effectiveness of IVR with direct cadaveric bone models in teaching upper and lower limb anatomy for first-year medical students. A randomized, double-blind crossover non-inferiority trial was conducted. Participants were first-year medical students from a single University. Exclusion criteria included students who undertook prior undergraduate or graduate degrees in anatomy. In the first stage of the study, students were randomized in a 1:1 ratio to IVR or cadaveric bone groups studying upper limb skeletal anatomy. All students were then crossed over and used cadaveric bone or IVR to study lower limb skeletal anatomy. All students in both groups completed a pre-and post-intervention knowledge test. The educational content was based on the University of Toronto Medical Anatomy Curriculum. The Oculus Quest 2 Headsets (Meta Technologies) and PrecisionOS Anatomy application (PrecisionOS Technology) were utilized for the virtual reality component. The primary endpoint of the study was student performance on the pre-and post-intervention knowledge tests. We hypothesized that student performance in the IVR groups would be comparable to the cadaveric bone group. 50 first-year medical students met inclusion criteria and were computer randomized (1:1 ratio) to IVR and cadaveric bone group for upper limb skeletal anatomy education. Forty-six students attended the study, 21 completed the upper limb modules, and 19 completed the lower limb modules. Among all students, average score on the pre-intervention knowledge test was 14.6% (Standard Deviation (SD)=18.2%) and 25.0% (SD=17%) for upper and lower limbs, respectively. Percentage increase in students’ scores between pre-and post-intervention knowledge test, in the upper limb for IVR, was 15 % and 16.7% for cadaveric bones (p = 0. 2861), and for the lower limb score increase was 22.6% in the IVR and 22.5% in the cadaveric bone group (p = 0.9356). In this non-inferiority crossover randomized controlled trial, we found no significant difference between student performance in knowledge tests after using IVR or cadaveric bones. Immersive virtual reality and cadaveric bones were equally effective in skeletal anatomy education. Going forward, with advances in VR technologies and anatomy applications, we can expect to see further improvements in the effectiveness of these technologies in anatomy and surgical education. These findings have implications for medical schools having challenges in acquiring cadavers and cadaveric parts

Novel immersive virtual reality (IVR) technologies are revolutionizing medical education. Virtual anatomy education using head-mounted displays allows users to interact with virtual anatomical objects, move within the virtual rooms, and interact with other virtual users. While IVR has been shown to be more effective than textbook learning and 3D computer models presented in 2D screens, the effectiveness of IVR compared to cadaveric models in anatomy education is currently unknown. In this study, we aim to compare the effectiveness of IVR with direct cadaveric bone models in teaching upper and lower limb anatomy for first-year medical students. A randomized, double-blind crossover non-inferiority trial was conducted. Participants were first-year medical students from a single University. Exclusion criteria included students who undertook prior undergraduate or graduate degrees in anatomy. In the first stage of the study, students were randomized in a 1:1 ratio to IVR or cadaveric bone groups studying upper limb skeletal anatomy. All students were then crossed over and used cadaveric bone or IVR to study lower limb skeletal anatomy. All students in both groups completed a pre-and post-intervention knowledge test. The educational content was based on the University of Toronto Medical Anatomy Curriculum. The Oculus Quest 2 Headsets (Meta Technologies) and PrecisionOS Anatomy application (PrecisionOS Technology) were utilized for the virtual reality component. The primary endpoint of the study was student performance on the pre-and post-intervention knowledge tests. We hypothesized that student performance in the IVR groups would be comparable to the cadaveric bone group. 50 first-year medical students met inclusion criteria and were computer randomized (1:1 ratio) to IVR and cadaveric bone group for upper limb skeletal anatomy education. Forty-six students attended the study, 21 completed the upper limb modules, and 19 completed the lower limb modules. Among all students, average score on the pre-intervention knowledge test was 14.6% (Standard Deviation (SD)=18.2%) and 25.0% (SD=17%) for upper and lower limbs, respectively. Percentage increase in students’ scores between pre-and post-intervention knowledge test, in the upper limb for IVR, was 15 % and 16.7% for cadaveric bones (p = 0. 2861), and for the lower limb score increase was 22.6% in the IVR and 22.5% in the cadaveric bone group (p = 0.9356). In this non-inferiority crossover randomized controlled trial, we found no significant difference between student performance in knowledge tests after using IVR or cadaveric bones. Immersive virtual reality and cadaveric bones were equally effective in skeletal anatomy education. Going forward, with advances in VR technologies and anatomy applications, we can expect to see further improvements in the effectiveness of these technologies in anatomy and surgical education. These findings have implications for medical schools having challenges in acquiring cadavers and cadaveric parts

Diagnostic interpretation error of paediatric musculoskeletal (MSK) radiographs can lead to late presentation of injuries that subsequently require more invasive surgical interventions with increased risks of morbidity. We aimed to determine the radiograph factors that resulted in diagnostic interpretation challenges for emergency physicians reviewing pediatric MSK radiographs. Emergency physicians provided diagnostic interpretations on 1,850 pediatric MSK radiographs via their participation in a web-based education platform. From this data, we derived interpretation difficulty scores for each radiograph using item response theory. We classified each radiograph by body region, diagnosis (fracture/dislocation absent or present), and, where applicable, the specific fracture location(s) and morphology(ies). We compared the interpretation difficulty scores by diagnosis, fracture location, and morphology. An expert panel reviewed the 65 most commonly misdiagnosed radiographs without a fracture/dislocation to identify normal imaging findings that were commonly mistaken for fractures. We included data from 244 emergency physicians, which resulted in 185,653 unique radiograph interpretations, 42,689 (23.0%) of which were diagnostic errors. For humerus, elbow, forearm, wrist, femur, knee, tibia-fibula radiographs, those without a fracture had higher interpretation difficulty scores relative to those with a fracture; the opposite was true for the hand, pelvis, foot, and ankle radiographs (p < 0 .004 for all comparisons). The descriptive review demonstrated that specific normal anatomy, overlapping bones, and external artefact from muscle or skin folds were often mistaken for fractures. There was a significant difference in difficulty score by anatomic locations of the fracture in the elbow, pelvis, and ankle (p < 0 .004 for all comparisons). Ankle and elbow growth plate, fibular avulsion, and humerus condylar were more difficult to diagnose than other fracture patterns (p < 0 .004 for all comparisons). We identified actionable learning opportunities in paediatric MSK radiograph interpretation for emergency physicians. We will use this information to design targeted education to referring emergency physicians and their trainees with an aim to decrease delayed and missed paediatric MSK injuries

Diagnostic interpretation error of paediatric musculoskeletal (MSK) radiographs can lead to late presentation of injuries that subsequently require more invasive surgical interventions with increased risks of morbidity. We aimed to determine the radiograph factors that resulted in diagnostic interpretation challenges for emergency physicians reviewing pediatric MSK radiographs. Emergency physicians provided diagnostic interpretations on 1,850 pediatric MSK radiographs via their participation in a web-based education platform. From this data, we derived interpretation difficulty scores for each radiograph using item response theory. We classified each radiograph by body region, diagnosis (fracture/dislocation absent or present), and, where applicable, the specific fracture location(s) and morphology(ies). We compared the interpretation difficulty scores by diagnosis, fracture location, and morphology. An expert panel reviewed the 65 most commonly misdiagnosed radiographs without a fracture/dislocation to identify normal imaging findings that were commonly mistaken for fractures. We included data from 244 emergency physicians, which resulted in 185,653 unique radiograph interpretations, 42,689 (23.0%) of which were diagnostic errors. For humerus, elbow, forearm, wrist, femur, knee, tibia-fibula radiographs, those without a fracture had higher interpretation difficulty scores relative to those with a fracture; the opposite was true for the hand, pelvis, foot, and ankle radiographs (p < 0 .004 for all comparisons). The descriptive review demonstrated that specific normal anatomy, overlapping bones, and external artefact from muscle or skin folds were often mistaken for fractures. There was a significant difference in difficulty score by anatomic locations of the fracture in the elbow, pelvis, and ankle (p < 0 .004 for all comparisons). Ankle and elbow growth plate, fibular avulsion, and humerus condylar were more difficult to diagnose than other fracture patterns (p < 0 .004 for all comparisons). We identified actionable learning opportunities in paediatric MSK radiograph interpretation for emergency physicians. We will use this information to design targeted education to referring emergency physicians and their trainees with an aim to decrease delayed and missed paediatric MSK injuries

Introduction. The constitutional knee anatomy in the coronal plane includes the distal femoral joint line obliquity (DFJLO) which in most patients is in slight valgus positioning. Despite this native anatomy, the mechanical positioning of the femoral component during primary total knee arthroplasty (TKA) often ignores the native DFJLO opting to place the femur in a set degree of valgus that varies upon the practitioner's practice and experience. Unfortunately, this technique is likely to generate high rate of distal lateral femoral overstuffing. This anatomical mismatch might be a cause of anterior knee pain and therefore partly explain the adverse functional outcomes of mechanically aligned (MA) TKA. Our study aims at assessing the relationship between constitutional knee anatomy and clinical outcomes of MA TKA. We hypothesized that a negative relationship would be found between the constitutional frontal knee deformity, the distal femoral joint line obliquity, and functional outcomes of MA TKA with a special emphasize on patellofemoral (PF) specific outcomes. Methods. One hundred and thirteen patients underwent MA TKA (posterior-stabilized design) for primary end-stage knee osteoarthritis. They were prospectively followed for one year using the New KSS 2011 and HSS Patella score. Residual anterior knee pain was also assessed. Knee phenotypes using anatomical parameters (such as HKA, HKS, DFJLO and LDFA (Lateral distal femoral angle)) were measured from preoperative and postoperative lower-limb EOS® images (Biospace, Paris, France). We assessed the relationship between the knee anatomical parameters and the functional outcome scores at 1 year postoperatively. Results. We investigated four groups according to the preoperative obliquity of the distal femur and HKA. The group with high DFJLO and varus knee deformity demonstrated lower HSS scores (drop>10%, p=0.03) and higher rate of anterior knee pain (p=0.03). Higher postoperative variation of LDFA was associated with lower HSS scores (r = −0.2367, p=0.03) and with higher preoperative DFJLO (p=0.0001) due to the MA technique. Knee phenotypes with LDFA<87° presented higher risk of variation of LDFA. No correlation was found using New KSS 2011 outcomes at one-year follow-up. Discussion/Conclusion. Disregard of the constitutional knee anatomy (LDFA and DFJLO) when performing a MA TKA may generate a non-physiologic knee kinematics that impact patellofemoral outcomes and resulting in residual anterior knee pain. While these results are restricted to modern posterior-stabilized TKA design, recent in silico and in vitro studies supported the negative effect of the lateral overstuffing of the femoral component in the coronal plane during knee flexion. This study provides further evidence that suggest patient-specific anatomical considerations are needed to optimize component position and subsequent outcomes following primary TKA. Additional studies are needed to integrate the rotational status of the femoral component in this analysis. For any figures or tables, please contact authors directly

Introduction. Variation in resection thickness of the femur in Total Knee Arthroplasty (TKA) impacts the flexion and extension tightness of the knee. Less well investigated is how variation in patient anatomy drives flexion or extension tightness pre- and post- operatively. Extension and flexion stability of the post TKA knee is a function of the tension in the ligaments which is proportional to the strain. This study sought to investigate how femoral ligament offset relates to post-operative navigation kinematics and how outcomes are affected by component position in relation to ligament attachment sites. Method. A database of TKA patients operated on by two surgeons from 1-Jan-2014 who had a pre-operative CT scan were assessed. Bone density of the CT scan was used to determine the medial and lateral collateral attachments. Navigation (OmniNav, Raynham, MA) was used in all surgeries, laxity data from the navigation unit was paired to the CT scan. 12-month postoperative Knee Osteoarthritis and Outcome Score (KOOS) score and a postoperative CT scan were taken. Preoperative segmented bones and implants were registered to the postoperative scan to determine change in anatomy. Epicondylar offsets from the distal and posterior condyles (of the native knee and implanted components), resections, maximal flexion and extension of the knee and coronal plane laxity were assessed. Relationships between these measurements were determined. Surgical technique was a mix of mechanical gap balancing and kinematically aligned knees using Omni (Raynham, MA) Apex implants. Results. 119 patients were identified in the database. 60% (71) were female and the average age was 69.0 years (+/− 8.1). The average distal femoral bone resection was 7.5 mm (+/− 1.6) medially and 5.4 mm (+/− 2.1) laterally, and posterior 10.2 mm (+/− 1.7) medially and 8.4 mm (+/− 1.8) laterally, with implant replacement thicknesses 9 mm distally and 11 mm posterior. Maximum flexion of the knee post implantation was 121.5° (+/− 8.1) from a preoperative value of 117.9° (+/− 9.5). Change in the collateral ligament offsets brought on by surgery had significant correlations with several laxity and flexion measures. Increase in the posterior offset of the medial collateral attachment brought on by surgery was shown to decrease the maximum flexion attained (coefficient = −0.53, p < 0.001), Figure 1. Increased distal medial offset post-operatively compared to the posterior offset is significantly correlated with improved KOOS pain outcomes (coefficient = 0.23, p = 0.01). Similarly, a decrease in the distal offset of the lateral collateral ligament increased the coronal plane laxity in extension (coefficient = 0.37, p < 0.001), while the posterior lateral resection was observed to correlate with postoperative coronal laxity in flexion (coefficient = 0.42, p < 0.001). Conclusions. Accounting for variation in ligament offset during surgically planning may improve balancing outcomes. Although new alignment approaches, such as kinematic alignment, have been able to demonstrate improvements in short term outcomes, elimination of postoperative dissatisfaction has not been achieved. The interaction of an alignment strategy with a given patient's specific anatomy may be the key to unlocking further TKA patient outcome gains

Primary total hip replacement (THR) in patients with abnormal/altered proximal femoral anatomy/narrow canals presents a technical challenge. There are only limited standard prosthetic stems available to deal with narrow canals or abnormal morphology. Many prefer to use expensive custom implants which often have a lag time to manufacture and do not always have long term published outcomes. We present results of the Asian C-stem (which is a standard implant available on the shelf) used in patients predominantly of Caucasian origin with abnormal proximal femoral anatomy. We retrospectively reviewed clinic-radiological results of 131 patients (131 stems) who underwent primary THR using Asian C-stem at Wrightington Hospital till their latest follow up. Revision for any reason was considered as primary end point. Mean age at surgery was 50.8 years (16 – 80). The 2 commonest indications were primary osteoarthritis (66 patients) and hip dysplasia (54 patients). Mean follow up was 43.5 months with a minimum follow up of 12 months and maximum follow up of 97 months. There were 2 recurrent dislocations and 1 hip subluxed twice. One dislocation needed revision surgery. 1 patient underwent acetabular revision for loosening. There was no stem failure, obvious loosening or loss of fixation in any patients in our series with regards to the Asian C-stem. There were no infections and intra-operative perforations or fractures. C-stem Asian is a reliable implant for patients undergoing THR with abnormal proximal femoral anatomy or narrow canals. Long term follow up is essential

Background. Degeneration of the shoulder joint is a frequent problem. There are two main types of shoulder degeneration: Osteoarthritis and cuff tear arthropathy (CTA) which is characterized by a large rotator cuff tear and progressive articular damage. It is largely unknown why only some patients with large rotator cuff tears develop CTA. In this project, we investigated CT data from ‘healthy’ persons and patients with CTA with the help of 3D imaging technology and statistical shape models (SSM). We tried to define a native scapular anatomy that predesignate patients to develop CTA. Methods. Statistical shape modeling and reconstruction:. A collection of 110 CT images from patients without glenohumeral arthropathy or large cuff tears was segmented and meshed uniformly to construct a SSM. Point-to-point correspondence between the shapes in the dataset was obtained using non-rigid template registration. Principal component analysis was used to obtain the mean shape and shape variation of the scapula model. Bias towards the template shape was minimized by repeating the non-rigid template registration with the resulting mean shape of the first iteration. Eighty-six CT images from patients with different severities of CTA were analyzed by an experienced shoulder surgeon and classified. CT images were segmented and inspected for signs of glenoid erosion. Remaining healthy parts of the eroded scapulae were partitioned and used as input of the iterative reconstruction algorithm. During an iteration of this algorithm, 30 shape components of the shape model are optimized and the reconstructed shape is aligned with the healthy parts. The algorithm stops when convergence is reached. Measurements. Automatic 3D measurements were performed for both the healthy and reconstructed shapes, including glenoid version, inclination, offset and critical shoulder angle. These measurements were manually performed on the mean shape of the shape model by a surgeon, after which the point-to-point correspondence was used to transfer the measurements to each shape. Results. The critical shoulder angle was found to be significantly larger for the CTA scapulae compared to the references (P<0.01). When analyzing the classified scapulae significant differences were found for the version angle in the scapulae of group 4a/4b and the critical shoulder angle of group 3 when compared to the references (P<0.05). Conclusion. Patients with CTA have a larger critical shoulder angle compared with reference patients. Some significant differences are found between the scapulae from patients in different stages of CTA and healthy references, however the differences are smaller than the accuracy of the SSM reconstruction. Therefore, we are unable to conclude that there is a predisposing anatomy in terms of glenoid version, inclination or offset for CTA

Introduction. According to the literature, the gait does not return to normal after THA. However, the three-dimensional hip anatomy is usually not assessed before and after surgery. Our hypothesis was that an accurate reconstruction of the hip anatomy, based on a three-dimensional preoperative planning, may normalize the gait after THA. Material and method. 18 consecutive patients, graded Charnley A, aged of 59.3 ±13 years, underwent THA for unilateral primary osteoarthritis using a direct anterior minimal invasive approach. A 3D computerised planning was performed, the implants size and position were chosen in order to restore, the leg length, the off-set, the centre of rotation and the anteversion angles (Figure 1). At 1 year follow up, a 3D gait analysis was performed and included 29 parameters describing the kinetics and the kinematics. Each patient was compared to himself using the contra-lateral healthy hip, as well as to a group of 13 healthy volunteers. Results. The real implants were the same than the ones planned in all the patients. The hip anatomy was restored with a high accuracy: 0.1±3mm for the hip rotation centre, −1.4±3 mm for the leg length and −0.9±3.5mm for the femoral offset. With respect to the gait, there was no significant difference between the operated side and the control-lateral leg. When compared to the control group, all the patients were within the normal range for all the parameters (Figure 2). Discussion and conclusion. The results suggest that the combination of an accurate 3D reconstruction and a direct anterior minimal invasive approach may allow to achieve a normal gait after THA at one year follow up

Purpose:. To determine the insertion of the different layers of the rotator cuff and apply it to rotator cuff tears. Anatomical insertion of the rotator cuff holds the key to a proper anatomical repair. Method:. A study of the rotator cuff insertion was done in conjunction with MSc student department Anatomy. The rotator cuff consists of a capsular and tendinous layer. They have different mechanical properties. The capsular layer inserts ± 3 mm more medially on the tuberosity and the tendinous layer more laterally. It was shown that the superficial layer extends beyond the greater tuberosity and connects the supra-spinatus tendon to the sub-scapularis tendon via the bicepital groove. This connection was called the “rotator hood”. The “rotator hood” has a mechanically advantageous insertion, is a strong structure with a compressive force on the proximal humerus. Conclusion:. 1. The rotator cuff inserts on the greater tuberosity as two separate entities. 2. The capsular layer inserts on the more medial 2–3 mm. 3. The tendinous layer is attached over a broader more lateral area giving it a mechanical advantage. 4. The tendinous layer of supra-spinatus extends beyond the tuberosity to connect to the sub-scapularis tendon providing an even greater mechanical advantage

A good understanding of musculoskeletal pathologies not only requires a good knowledge of normal human anatomy but also an insight in human evolution and development. Biomechanical studies of the musculoskeletal system have greatly improved our understanding of the human musculoskeletal system via medical imaging, modeling and simulation techniques. The same techniques are, however, also used in the study of nonhuman species and a comparison of human and nonhuman data can yield interesting insight in form-function relationships and mechanical constraints on motion. Anatomical and biomechanical studies on dogs and rabbits have already yielded valuable insight in disease mechanisms and development of musculoskeletal pathologies such as osteoarthritis (OA). Nonhuman primates have, however, rarely been studied in this context, though they may prove particularly valuable as they can provide us with an evolutionary context of modern human anatomy and pathology. The high prevalence of osteoarthritis in modern humans and its rare occurrence in wild primates has previously been explained as due to human joints being ‘underutilized’ or ‘underdesigned’. Modern humans are highly specialized for bipedalism, while nonhuman primates typically use a wide range of locomotor modes and joint postures to travel through the three-dimensionally complex forest canopy. These hypotheses can, however, be challenged, as it seems more likely that the low occurrence of OA in wild primates is due to a combination of underreporting of the disease and absence of the ageing effect in these species. Our understanding of musculoskeletal function and disease in modern humans would clearly benefit from more studies investigating the occurrence and characteristics of OA in nonhuman primates

Humeral head size is defined by the radius of curvature and the thickness of the articular segment. This ratio of radius to thickness is within a narrow range with an average of 0.71. The articular surface of the normal humeral head measured within the AP plane is defined by three landmarks on the non-articular surface of the proximal humerus. The perfect circle concept can be applied for assessment of the anatomic reconstruction of the post-operative x-rays and more importantly can be used intra-operatively as a guide when choosing the proper prosthetic humeral head component. The humeral head is an elliptical shape with its AP dimension being approximately 2 mm less than the SI dimension. This shape contributes to the roll and translation of the normal shoulder but is not replicated by the spherical shape of the prosthetic humeral head. The glenoid vault has a consistent 3D shape and use of the vault model within 3D planning software can define the patient's pre-morbid anatomy, specifically the location of the joint line and patient specific version and inclination. Use of this tool can assist the surgeon in defining the optimal implant and its location. In patients with little or no bone loss, a symmetric glenoid implant is often ideal for resurfacing. When there is asymmetric bone loss, often seen posteriorly with osteoarthritis, an asymmetric posteriorly augmented component can improve the ability to correct the deformity while maintaining the native joint line. It is suggested that these augmented implants in selected patients will help restore and maintain humeral alignment and lessen the risk for residual posterior humeral head subluxation and eccentric loading of the glenoid component

Purpose. Intramedullary fixation of clavicle fractures requires an adequate medullary canal to accommodate the fixation device used. This computer tomography anatomical study of the clavicle and its medullary canal describes its general anatomy and provides the incidence of anatomical variations of the medullary canal that complicates intramedullary fixation of midshaft fractures. Methods. Four hundred and eighteen clavicles in 209 patients were examined using computer tomography imaging. The length and curvatures of the clavicles were measured as well as the height and width of the clavicle and its canal at various pre-determined points. The start and end of the medullary canal from the sternal and acromial ends of the clavicle were determined. The data was grouped according to age, gender and lateralization. Results. The average length of the clavicle was 151.15mm with the average sternal and acromial curvature being 146° and 133° respectively. The medullary canal starts on average 6.59mm from the sternal end and ends 19.56mm from the acromial end with the average height and width of the canal at the middle third being 5.61mm and 6.63mm respectively. Conclusion. The medullary canal of the clavicle is large enough to accommodate commonly used intramedullary devices in the majority of cases. The medullary canal extends far enough medially and laterally to ensure that an intramedullary device can be passed far enough medially and laterally past the fracture site to ensure stable fixation in most middle third clavicle fractures. An alternative surgical option should be available in theatre when treating females as the medullary canal is too small to pass an intramedullary device past the fracture site on rare occasions. Fractures located within 40mm of the lateral or medial ends of the clavicle should not be treated by intramedullary fixation as adequate stability is unlikely to be achieved. MULTIPLE DISCLOSURES

Introduction. Getting the distal locking screw lengths right in volar locking plate fixation of distal radius is crucial. Long screws can lead to extensor tendon ruptures whereas short screws can lead to failure of fixation, especially if there is dorsal comminution of the fracture. The aim of our study was to determine the distal radius anatomy in relation to sagittal lengths and distance between dorsal bone edge and extensor tendons based on MRI scan. Method. One hundred consecutive MRI scans of wrist were reviewed by two of the authors on two occasions. All MRI scans were performed for different wrist pathologies except distal radius fractures or tumours. An axial image, two cuts proximal to the last visible articular surface, was selected. Sagittal length at 5 different widths, maximum volar width, radial overhang over distal radio-ulnar joint and the distance between dorsal bone edge and extensor tendons were measured. Results. A total of 120 MRI scans were included of which 74 were women and 46 were men. Mean volar width was 32mm and longest sagittal length was 22 mm (at Lister's tubercle). Length radial to Lister's tubercle was the shortest (17mm) and ulnar sides were 21mm and 29mm. Male measurements were mean 3mm longer than females. Mean radial overhang over DRUJ was 4mm. Distance from bone to tendons was within 2mm of dorsal radius edge. Conclusion. The study provides a reference guide to average screw lengths at different widths of distal radius in males and females. EPL tendon is closest to bone although all the extensor tendons are within 2mm of bone edge and carry a risk of injury from drill and screw placement. DRUJ is also at risk of injury if screws are placed within 4mm of ulnar edge of distal radius

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

Introduction. In the evaluation of patients with pre-arthritic hip disorders, making the correct diagnosis and identifying the underlying bone pathology is of upmost importance to achieve optimal patient outcomes. 3-dimensional imaging adds information for proper preoperative planning. CT scans have become the gold standard for this, but with the associated risk of radiation exposure to this generally younger patient cohort. Purpose. To determine if 3D-MR reconstructions of the hip can be used to accurately demonstrate femoral and acetabular morphology in the setting of femoroacetabular impingement (FAI) and development dysplasia of the hip (DDH) that is comparable to CT imaging. Materials and Methods. We performed a retrospective review of 14 consecutive patients with a diagnosis of FAI or DDH that underwent both CT and MRI scans of the same hip with 3D reconstructions. 2 fellowship trained musculoskeletal radiologists reviewed all scans, and a fellowship trained hip preservation surgeon separately reviewed scans for relevant surgical parameters. All were blinded to the patients' clinical history. The 3D reconstructions were evaluated by radiologists for the presence of a CAM lesion and acetabular retroversion, while the hip preservation surgeon also evaluated CAM extent using a clock face convention of a right hip, location of femoral head blood supply, and morphological anterior inferior iliac spine (AIIS) variant. The findings on the 3D CT reconstructions were considered the reference standard. Results. Of 14 patients, there were 9 females and 5 males with a mean age 32 (range 15–42). There was no difference in the ability of MRI to detect the presence of a CAM lesion (100% agreement between 3D-MR and 3D-CT, p=1), AIIS morphology (p=1, mode=type 1 variant), or acetabular retroversion (85.7%, p=0.5). 3D-MR had a sensitivity and specificity of 100 in detecting a CAM lesion relative to 3D-CT. Four CT studies were inadequate to adequately evaluate for presence of a CAM. Five CT studies were inadequate to evaluate for location of the femoral head vessels, while MRI was able to determine location in those patients. In the 10 remaining patients for presence of CAM, and nine patients for femoral head vessel location, there was no statistically significant difference between 3D-MR and 3D-CT in determining the location of CAM lesion on a clock face (p=0.8, mean MRI = 12:54, mean CT: 12:51, SD = 66 mins MR, 81 mins CT) or in determining vessel location (p=0.4, MR mean 11:23, CT mean 11:36, SD 33 mins for both). Conclusion. 3D MRI reconstructions are as accurate as 3D CT reconstructions in evaluating osseous morphology of the hip, and may be superior to CT in determining other certain clinically relevant hip parameters. 3D-MR was equally useful in determining the presence and extent of a CAM lesion, acetabular retroversion, and AIIS morphologic variant, and more useful than 3D CT in determining location of the femoral head vessels. In evaluating FAI or hip dysplasia, a 3D-MR study is sufficient to evaluate both soft tissue and osseous anatomy, sparing the need for a 3D CT scan and its associated radiation exposure and cost

Introduction:. Recent studies have concluded that gender influences hip morphology at the time of surgery as well as dysplastic development of the hip. This may lead to a particular choice of implant including stem design and/or neck modularity. In this study we hypothesized that not only gender but also morphotype and etiology (primary osteoarthritis versus aseptic osteonecrosis) may be a significant factor to predict the anatomy of the hip at the time of total hip arthroplasty (THA). Methods:. We reviewed 690 patients undergoing THA for primary arthritis (OA) or avascular osteonecrosis (AVN) between April 2000 and June 2005 and stratified each into three groups based on their anatomic constitution: endomorph (EN), ectomorph (ECT), or mesomorph (ME) (determined by the ratio: pelvic width/total leg length measured on full-length X-rays). Two independent observers measured twice four parameters on preoperative CT scan: neck-shaft-angle angle (NSA), femoral offset value (FO), helitorsion (Ht) value and femoral neck anteversion (Av). Results:. No significant difference were observed between men and women for the four parameters with respectively: NSA (129.29° ± 5.6 versus 129.3° ± 5.7), Av (20.3° ± 8.6 versus 20.27° ± 8.6), FO (19.7 mm ± 3.98 versus 19.74 mm ± 3.98) and Ht (19.97° ± 12.2 for men and 19.94° ± 12.3). Significant difference were found for NSA: 130.1° ± 5.8 for ECT, 129.55° ± 6 for MES and 128.2° ± 5,1 for EN with p < 0.01. For Av, the values were: 18.9° ± 8.7 for ECT, 20.74° ± 8.1 for MES and 21.2° ± 8.95 for EN (p < 0.01). For FO the values were 19.1 mm ± 3.9 for ECT, 19.7 ± 4 for MES and and 20.44 mm ± 3.93 for EN (p < 0.01). No difference was found for Ht between the 3 groups. A significant difference was found between patients suffering from OA and AVN: mean NSA was 130.36° ± 8.79 for OA patients versus 127.35° ± 8.38 for those who had an AVN (p < 0.01). A value was 17.06° ± 8.1 for OA and 23.7 ± 7.89 for AVN (p < 0.01). FO value was 18.72 mm ± 3.71 for OA versus 20.75 mm ± 4.15 for AVN (p <0.01). And Ht was 18.94° ± 9.64 for OA and 21.05° ± 14.5 for AVN patients (p < 0.01). Discussion and conclusion:. Patients with short and wide morphotype (endomorph) had, irrespective of gender, lower values of NSA with greater anterversion and offset values, whereas patients with long and narrow morphotype (ectomorph) had higher values of NSA and smaller Av and FO (figure 1). In the same time patients suffering from AVN have lower NSA angle, lower Av, smaller FO and Ht (figure 2). Femoral stem design should allow the consideration of these differences to optimize the reconstruction of the hip at the time of THA including pre-operative and intra-operative modularity

Purpose:. Anterior positioning of a cephomedullary nail (CMN) in the distal femur occurs in up to 88% of cases. Conventionally, this is considered to occur because of a mismatch between the radius of curvature (ROC) of the femur and that of available implants. The hypothesis for this study was that the relative thicknesses of the cortices of the femur, particularly the posterior cortex are important in determining the final position of an intramedullary implant and that the posterior cortical thickness corresponds to the linea aspera anatomically. The aim was to determine if these measurements changed with age. Method:. This study used the data from CT scans undertaken as part of routine clinical practice in 919 patients with intact left femora (median age 66 years, range 20–93 years; 484 male and 435 female). The linea aspera was defined manually on the template bone by consensus between two orthopaedic surgeons and two anatomists. The length of the femur was measured from the tip of the greater trochanter proximally to the intercondylar notch distally. Transverse intervals were plotted on the femur between 25%–60% femoral bone length (5% increments). The linea aspera was then defined at each interval on the template bone and mapped automatically to all individual femora in the database. Results:. The linea aspera was found to be internally rotated as compared to the sagittal plane referenced off the posterior femoral condyles. An age related change in the posterior/anterior cortical thickness ratio was demonstrated. This ratio increases in all age groups from 25–60% bone length being maximal around 45–55% bone length. The ≥80 year old cohort shows a disproportional posterior/anterior ratio increase of 70.0% from 25–50% bone length as compared to 48.1% for the <40 year old cohort which is statistically significant (Mann-Whitney-Test p<0.05, α = 5%). Conclusion:. This study presents a novel method of investigating femoral anatomy with directly relevance to orthopaedic procedures. This study has shown that assessment in the sagittal plane may be inaccurate because the linea aspera changes in this plane throughout the length of the femur. It also shows the loss of the centering influence of the corticies with age with a relative thinning of the anterior cortex with a concomitant thickening of the posterior cortex moving distally in the femur. This has a very direct and significant influence on the positioning of intramedullary femoral implants explaining the preponderance of anterior malpositioning of intramedullary implants in the elderly

Introduction. Atlanto-occipital dislocation is rare and usually fatal. Stabilisation is typically from Occiput to C2, sacrificing atlanto-axial movement. To preserve movement, screw fixation from the articular mass of C1 to the occipital condyle has been described. Amongst other structures, the hypoglossal nerve is at risk. No previous study has addressed the anatomy of the hypoglossal canal in relation to screw trajectory. We aim to identify landmarks to aid safe screw passage into the occipital condyle. Methods. 20 dry skulls provided 40 hypoglossal canals (HCs) and 40 occipital condyles (OCs). No distinction was made between sex, race or age. 9 parameters were measured for each HC, and relation to skull base was noted. Results. The mean length of the HC was 10mm (range 8-14). The extra-cranial foramen of the HC is located lateral to the intra-cranial foramen (30 degrees, range 19-45). 19 out of 20 skulls had HCs with intra-cranial foramina more caudal than their extra-cranial foramina, ie the HC angled cranially (22 degrees, range 7-51). 36 out of 40 OCs were found to be wholly inferior to the rim of the foramen magnum, with 4 (in 2 skulls) whose bodies lay below, but extended above, this landmark. Every single HC was situated, in its entirety, superior to the rim of the foramen magnum. Conclusions. The trajectory of the hypoglossal canal from its intra-cranial foramen is antero-supero-lateral. It is situated, in its entirety, superior to the rim of the foramen magnum. The thickest portion of the occipital condyle is antero-medial. The screw passage from posterior through the C1 articular mass ought to aim for the anterior, superior, medial quadrant of the occipital condyle, and should not pass cranial to the rim of the foramen magnum in order to minimise the risk to the hypoglossal nerve

PURPOSE:. Unicompartmental knee arthroplasty (UKA) is becoming more commonly performed and is more technically challenging than total knee replacement. Retention of the anterior and posterior cruciate ligaments requires more accurate re-creation of the patient's normal anatomic posterior slope with UKA. Purpose of this study was to accurately determine the posterior tibial slope in patients having medial or lateral UKA performed. METHODS:. Retrospective review was performed of 2,395 CT scans performed for a customized UKA implant. Standard CT technique was used and the posterior slope was measured on the involved side of the proximal tibia. RESULTS:. CT measurements from 2031 knees undergoing medial UKAs had an average pre-operative posterior slope of 6.8 deg (SD 3.3), in these patients the posterior slope was between: 0–4 deg in 430 knees (21.2%), 4–7 deg in 696 knees (34.3%), 7–10 deg in 545 knees (26.8%), >10 deg in 360 knees (17.7%), and 13 knees (0.6%) had a reversed (anterior) tibial slope. Measurements from the 364 knees undergoing lateral UKAs showed an average pre-operative posterior slope of 8.0 deg (SD 3.3), in these patients the posterior slope was between: 0–4 deg in 43 knees (11.8%), 4–7 deg in 100 knees (27.5%), 7–10 deg in 118 knees (32.4%), >10 deg in 103 knees (28.3%), and 1 knee (0.3%) had a reversed (anterior) tibial slope. CONCLUSION:. There is marked variability in the posterior slope of the proximal tibial with 44.5% of medial plateaus and 60.7% of lateral plateaus having more than 7 deg of posterior slope pre-operatively. This is the first large CT based review of posterior slope variation of the proximal tibia. If attempting to match the patient's proximal slope during UKA, a routine setting of 5 degrees posterior slope will produce a posterior slope less than the patient's native anatomy in more than 50% of patients