Aims. Although CT is considered the benchmark to measure femoral version, 3D biplanar radiography (hipEOS) has recently emerged as a possible alternative with reduced exposure to ionizing radiation and shorter examination time. The aim of our study was to evaluate femoral stem version in postoperative total hip arthroplasty (THA) patients and compare the accuracy of hipEOS to CT. We hypothesize that there will be no significant difference in calculated femoral stem version measurements between the two imaging methods. Methods. In this study, 45 patients who underwent THA between February 2016 and February 2020 and had both a postoperative CT and EOS scan were included for evaluation. A fellowship-trained musculoskeletal radiologist and radiological technician measured femoral version for CT and 3D EOS, respectively. Comparison of values for each imaging modality were assessed for statistical significance. Results. Comparison of the mean postoperative femoral stem version measurements between CT and 3D hipEOS showed no significant difference (p = 0.862). In addition, the two version measurements were strongly correlated (r = 0.95; p < 0.001), and the mean paired difference in postoperative femoral version for CT scan and 3D biplanar radiography was -0.09° (95% confidence interval -1.09 to 0.91). Only three stem measurements (6.7%) were considered outliers with a > 5° difference. Conclusion. Our study supports the use of low-dose biplanar radiography for the postoperative assessment of femoral stem version after THA, demonstrating high correlation with CT. We found no significant difference for postoperative femoral version when comparing CT to 3D EOS. We believe 3D EOS is a reliable option to measure postoperative femoral version given its advantages of lower radiation dosage and shorter examination time. Cite this article: Bone Joint J 2022;104-B(11):1196–1201

Aims. Malreduction of the syndesmosis has been reported in up to 52% of patients after fixation of ankle fractures. Multiple radiological parameters are used to define malreduction; there has been limited investigation of the accuracy of these measurements in differentiating malreduction from inherent anatomical asymmetry. The purpose of this study was to identify the prevalence of positive malreduction standards within the syndesmosis of native, uninjured ankles. Methods. Three observers reviewed 213 bilateral lower limb CT scans of uninjured ankles. Multiple measurements were recorded on the axial CT 1 cm above the plafond: anterior syndesmotic distance; posterior syndesmotic distance; central syndesmotic distance; fibular rotation; and sagittal fibular translation. Previously studied malreduction standards were evaluated on bilateral CT, including differences in: anterior, central and posterior syndesmotic distance; mean syndesmotic distance; fibular rotation; sagittal translational distance; and syndesmotic area. Unilateral CT was used to compare the anterior to posterior syndesmotic distances. Results. A difference of anterior to posterior syndesmotic distance > 2 mm was observed in 89% of ankles (n = 190) on unilateral CT assessment. Using bilateral CT, we found that 35% (n = 75) of normal ankles would be considered malreduced by current malreduction parameters. In 50 patients (23%), only one parameter was anomalous, 18 patients (8%) had two positive parameters and seven patients (3%) had three. Difference in fibular rotation had the lowest false positive rate of all parameters at 6%, whereas posterior syndesmotic distance difference had the highest at 15%. Conclusion. In this study, 35% of native, uninjured syndesmoses (n = 75) would be classified as malreduced by current diagnostic standards on bilateral CT and 89% had an asymmetric incisura on unilateral CT (n = 190). Current radiological parameters are insufficient to differentiate mild inherent anatomical asymmetry from malreduction of the syndesmosis. Cite this article: Bone Joint J 2021;103-B(1):178–183

The aim of this study was first, to determine whether CT scans undertaken to identify serious injury to the viscera were of use in detecting clinically unrecognised fractures of the thoracolumbar vertebrae, and second, to identify patients at risk of ‘missed injury’. . We retrospectively analysed CT scans of the chest and abdomen performed for blunt injury to the torso in 303 patients. These proved to be positive for thoracic and intra-abdominal injuries in only 2% and 1.3% of cases, respectively. However, 51 (16.8%) showed a fracture of the thoracolumbar vertebrae and these constituted our subset for study. There were eight women and 43 men with mean age of 45.2 years (15 to 94). There were 29 (57%) stable and 22 (43%) unstable fractures. Only 17 fractures (33.3%) had been anticipated after clinical examination. Of the 22 unstable fractures, 11 (50%) were anticipated. Thus, within the whole group of 303 patients, an unstable spinal injury was missed in 11 patients (3.6%); no harm resulted as they were all protected until the spine had been cleared. A subset analysis revealed that patients with a high Injury Severity Score, a low Glasgow Coma Scale and haemodynamic instability were most likely to have a significant fracture in the absence of positive clinical findings. This is the group at greatest risk. Clinical examination alone cannot detect significant fractures of the thoracolumbar spine. It should be combined with CT imaging to reduce the risk of missed injury

The cam-type deformity in femoroacetabular impingement is a 3D deformity. Single measurements using radiographs, CT or MRI may not provide a true estimate of the magnitude of the deformity. We performed an analysis of the size and location of measurements of the alpha angle (α°) using a CT technique which could be applied to the 3D reconstructions of the hip. Analysis was undertaken in 42 patients (57 hips; 24 men and 18 women; mean age 38 years (16 to 58)) who had symptoms of femoroacetabular impingement related to a cam-type abnormality. An α° of > 50° was considered a significant indicator of cam-type impingement. Measurements of the α° were made at different points around the femoral head/neck junction at intervals of 30°: starting at the nine o’clock (posterior), ten, eleven and twelve o’clock (superior), one, two and ending at three o’clock (anterior) position. The mean maximum increased α° was 64.6° (50.8° to 86°). The two o’clock position was the most common point to find an increased α° (53 hips; 93%), followed by one o’clock (48 hips; 84%). The largest α° for each hip was found most frequently at the two o’clock position (46%), followed by the one o’clock position (39%). Generally, raised α angles extend over three segments of the clock face. Single measurements of the α°, whether pre- or post-operative, should be viewed with caution as they may not be representative of the true size of the deformity and not define whether adequate correction has been achieved following surgery. Cite this article: Bone Joint J 2014;96-B:1167–71.

Advanced 3D imaging and CT-based navigation have emerged as valuable tools to use in total knee arthroplasty (TKA), for both preoperative planning and the intraoperative execution of different philosophies of alignment. Preoperative planning using CT-based 3D imaging enables more accurate prediction of the size of components, enhancing surgical workflow and optimizing the precision of the positioning of components. Surgeons can assess alignment, osteophytes, and arthritic changes better. These scans provide improved insights into the patellofemoral joint and facilitate tibial sizing and the evaluation of implant-bone contact area in cementless TKA. Preoperative CT imaging is also required for the development of patient-specific instrumentation cutting guides, aiming to reduce intraoperative blood loss and improve the surgical technique in complex cases. Intraoperative CT-based navigation and haptic guidance facilitates precise execution of the preoperative plan, aiming for optimal positioning of the components and accurate alignment, as determined by the surgeon’s philosophy. It also helps reduce iatrogenic injury to the periarticular soft-tissue structures with subsequent reduction in the local and systemic inflammatory response, enhancing early outcomes. Despite the increased costs and radiation exposure associated with CT-based navigation, these many benefits have facilitated the adoption of imaged based robotic surgery into routine practice. Further research on ultra-low-dose CT scans and exploration of the possible translation of the use of 3D imaging into improved clinical outcomes are required to justify its broader implementation. Cite this article: Bone Joint J 2024;106-B(9):892–897

Aims. To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time. Methods. We performed a single-centre historical prospective cohort study, including all patients with revision THA using the aMace CTAC between January 2017 and March 2021. A total of 18 patients (18 CTACs) were included. Models of the hemipelvis and the scaffold component of the CTACs were created by segmentation of CT scans. The CT scans were performed immediately postoperatively and at least one year after surgery. The amount of bone in contact with the scaffold was analyzed at both times, and the difference was calculated. Results. The mean time between the implantation and the second CT scan was two years (1 to 5). The mean age of the patients during CTAC implantation was 75 years (60 to 92). The mean scaffold-bone contact area increased from 16% (SD 12.6) to 28% (SD 11.9). The mean scaffold-bone distance decreased from a mean of 6.5 mm (SD 2.0) to 5.5 mm (SD 1.6). None of the CTACs were revised or radiologically loose. Conclusion. There was a statistically significant increase of scaffold-bone contact area over time, but the total contact area of the scaffold in relation to the acetabular bone remained relatively low. As all implants remained well fixed, the question remains to what extend the scaffold contributes to the observed stability, in relation to the screws. A future design implication might be an elimination of the bulky scaffold component. This design modification would reduce production costs and may optimize the primary fit of the implant. Cite this article: Bone Joint J 2024;106-B(4):359–364

Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029

Aims. The purpose of this study was to develop a convolutional neural network (CNN) for fracture detection, classification, and identification of greater tuberosity displacement ≥ 1 cm, neck-shaft angle (NSA) ≤ 100°, shaft translation, and articular fracture involvement, on plain radiographs. Methods. The CNN was trained and tested on radiographs sourced from 11 hospitals in Australia and externally validated on radiographs from the Netherlands. Each radiograph was paired with corresponding CT scans to serve as the reference standard based on dual independent evaluation by trained researchers and attending orthopaedic surgeons. Presence of a fracture, classification (non- to minimally displaced; two-part, multipart, and glenohumeral dislocation), and four characteristics were determined on 2D and 3D CT scans and subsequently allocated to each series of radiographs. Fracture characteristics included greater tuberosity displacement ≥ 1 cm, NSA ≤ 100°, shaft translation (0% to < 75%, 75% to 95%, > 95%), and the extent of articular involvement (0% to < 15%, 15% to 35%, or > 35%). Results. For detection and classification, the algorithm was trained on 1,709 radiographs (n = 803), tested on 567 radiographs (n = 244), and subsequently externally validated on 535 radiographs (n = 227). For characterization, healthy shoulders and glenohumeral dislocation were excluded. The overall accuracy for fracture detection was 94% (area under the receiver operating characteristic curve (AUC) = 0.98) and for classification 78% (AUC 0.68 to 0.93). Accuracy to detect greater tuberosity fracture displacement ≥ 1 cm was 35.0% (AUC 0.57). The CNN did not recognize NSAs ≤ 100° (AUC 0.42), nor fractures with ≥ 75% shaft translation (AUC 0.51 to 0.53), or with ≥ 15% articular involvement (AUC 0.48 to 0.49). For all objectives, the model’s performance on the external dataset showed similar accuracy levels. Conclusion. CNNs proficiently rule out proximal humerus fractures on plain radiographs. Despite rigorous training methodology based on CT imaging with multi-rater consensus to serve as the reference standard, artificial intelligence-driven classification is insufficient for clinical implementation. The CNN exhibited poor diagnostic ability to detect greater tuberosity displacement ≥ 1 cm and failed to identify NSAs ≤ 100°, shaft translations, or articular fractures. Cite this article: Bone Joint J 2024;106-B(11):1348–1360

Aims. Osteoporosis can determine surgical strategy for total hip arthroplasty (THA), and perioperative fracture risk. The aims of this study were to use hip CT to measure femoral bone mineral density (BMD) using CT X-ray absorptiometry (CTXA), determine if systematic evaluation of preoperative femoral BMD with CTXA would improve identification of osteopenia and osteoporosis compared with available preoperative dual-energy X-ray absorptiometry (DXA) analysis, and determine if improved recognition of low BMD would affect the use of cemented stem fixation. Methods. Retrospective chart review of a single-surgeon database identified 78 patients with CTXA performed prior to robotic-assisted THA (raTHA) (Group 1). Group 1 was age- and sex-matched to 78 raTHAs that had a preoperative hip CT but did not have CTXA analysis (Group 2). Clinical demographics, femoral fixation method, CTXA, and DXA data were recorded. Demographic data were similar for both groups. Results. Preoperative femoral BMD was available for 100% of Group 1 patients (CTXA) and 43.6% of Group 2 patients (DXA). CTXA analysis for all Group 1 patients preoperatively identified 13 osteopenic and eight osteoporotic patients for whom there were no available preoperative DXA data. Cemented stem fixation was used with higher frequency in Group 1 versus Group 2 (28.2% vs 14.3%, respectively; p = 0.030), and in all cases where osteoporosis was diagnosed, irrespective of technique (DXA or CTXA). Conclusion. Preoperative hip CT scans which are routinely obtained prior to raTHA can determine bone health, and thus guide femoral fixation strategy. Systematic preoperative evaluation with CTXA resulted in increased recognition of osteopenia and osteoporosis, and contributed to increased use of cemented femoral fixation compared with routine clinical care; in this small study, however, it did not impact short-term periprosthetic fracture risk. Cite this article: Bone Joint J 2023;105-B(3):254–260

Aims. The aim of this study was to analyze the true costs associated with preoperative CT scans performed for robotic-assisted total knee arthroplasty (RATKA) planning and to determine the value of a formal radiologist’s report of these studies. Methods. We reviewed 194 CT reports of 176 sequential patients who underwent primary RATKA by a single surgeon at a suburban teaching hospital. CT radiology reports were reviewed for the presence of incidental findings that might change the management of the patient. Payments for the scans, including the technical and professional components, for 330 patients at two hospitals were also recorded and compared. Results. There were 82 incidental findings in 61 CT studies, one of which led to a recommendation for additional testing. Across both institutions, the mean total payment for a preoperative scan was $446 ($8 to $3,870). The mean patient payment was $71 ($0 to $2,690). There was wide variation in payments between the institutions. In Institution A, the mean total payment was $258 ($168 to $264), with a mean patient payment of $57 ($0 to $100). The mean technical payment in this institution was $211 ($8 to $856), while the mean professional payment was $48 ($0 to $66). In Institution B, the mean total payment was $636 ($37 to $3,870), with a mean patient payment of $85 ($0 to $2,690). Conclusion. The total cost of a CT scan is low and a minimal part of the overall cost of the RATKA. No incidental findings identified on imaging led to a change in management, suggesting that the professional component could be eliminated to reduce costs. Further studies need to take into account the patient perspective and the wide variation in total costs and patient payments across institutions and insurances. Cite this article: Bone Joint J 2020;102-B(6 Supple A):79–84

Aims. The aim of this study was to assess arthritis of the basal joint of the thumb quantitatively using bone single-photon emission CT/CT (SPECT/CT) and evaluate its relationship with patients’ pain and function. Methods. We retrospectively reviewed 30 patients (53 hands) with symptomatic basal joint arthritis of the thumb between April 2019 and March 2020. Visual analogue scale (VAS) scores for pain, grip strength, and pinch power of both hands and Patient-Rated Wrist/Hand Evaluation (PRWHE) scores were recorded for all patients. Basal joint arthritis was classified according to the modified Eaton-Glickel stage using routine radiographs and the CT scans of SPECT/CT, respectively. The maximum standardized uptake value (SUVmax) from SPECT/CT was measured in the four peritrapezial joints and the highest uptake was used for analysis. Results. According to Eaton-Glickel classification, 11, 17, 17, and eight hands were stage 0 to I, II, III, and IV, respectively. The interobserver reliability for determining the stage of arthritis was moderate for radiographs (k = 0.41) and substantial for CT scans (k = 0.67). In a binary categorical analysis using SUVmax, pain (p < 0.001) and PRWHE scores (p = 0.004) were significantly higher in hands with higher SUVmax. Using multivariate linear regression to estimate the pain VAS, only SUVmax (B 0.172 (95% confidence interval (CI) 0.065 to 0.279; p = 0.002) showed a significant association. Estimating the variation of PRWHE scores using the same model, only SUVmax (B 1.378 (95% CI, 0.082 to 2.674); p = 0.038) showed a significant association. Conclusion. The CT scans of SPECT/CT provided better interobserver reliability than routine radiographs for evaluating the severity of arthritis. A higher SUVmax in SPECT/CT was associated with more pain and functional disabilities of basal joint arthritis of the thumb. This approach could be used to complement radiographs for the evaluation of patients with this condition. Cite this article: Bone Joint J 2021;103-B(8):1380–1385

Aims. To benchmark the radiation dose to patients during the course of treatment for a spinal deformity. Methods. Our radiation dose database identified 25,745 exposures of 6,017 children (under 18 years of age) and adults treated for a spinal deformity between 1 January 2008 and 31 December 2016. Patients were divided into surgical (974 patients) and non-surgical (5,043 patients) cohorts. We documented the number and doses of ionizing radiation imaging events (radiographs, CT scans, or intraoperative fluoroscopy) for each patient. All the doses for plain radiographs, CT scans, and intraoperative fluoroscopy were combined into a single effective dose by a medical physicist (milliSivert (mSv)). Results. There were more ionizing radiation-based imaging events and higher radiation dose exposures in the surgical group than in the non-surgical group (p < 0.001). The difference in effective dose for children between the surgical and non-surgical groups was statistically significant, the surgical group being significantly higher (p < 0.001). This led to a higher estimated risk of cancer induction for the surgical group (1:222 surgical vs 1:1,418 non-surgical). However, the dose difference for adults was not statistically different between the surgical and non-surgical groups. In all cases the effective dose received by all cohorts was significantly higher than that from exposure to natural background radiation. Conclusion. The treatment of spinal deformity is radiation-heavy. The dose exposure is several times higher when surgical treatment is undertaken. Clinicians should be aware of this and review their practices in order to reduce the radiation dose where possible. Cite this article: Bone Joint J 2021;103-B(4):1–7

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article: Bone Joint J 2021;103-B(5):822–827

Aims. We quantitatively compared the 3D bone density distributions on CT scans performed on scaphoid waist fractures subacutely that went on to union or nonunion, and assessed whether 2D CT evaluations correlate with 3D bone density evaluations. Methods. We constructed 3D models from 17 scaphoid waist fracture CTs performed between four to 18 weeks after fracture that did not unite (nonunion group), 17 age-matched scaphoid waist fracture CTs that healed (union group), and 17 age-matched control CTs without injury (control group). We measured the 3D bone density for the distal and proximal fragments relative to the triquetrum bone density and compared findings among the three groups. We then performed bone density measurements using 2D CT and evaluated the correlation with 3D bone densities. We identified the optimal cutoff with diagnostic values of the 2D method to predict nonunion with receiver operating characteristic (ROC) curves. Results. In the nonunion group, both the distal (100.2%) and proximal (126.6%) fragments had a significantly higher bone density compared to the union (distal: 85.7%; proximal: 108.3%) or control groups (distal: 91.6%; proximal: 109.1%) using the 3D bone density measurement, which were statistically significant for all comparisons. 2D measurements were highly correlated to 3D bone density measurements (Spearman’s correlation coefficient (R) = 0.85 to 0.95). Using 2D measurements, ROC curve analysis revealed the optimal cutoffs of 90.8% and 116.3% for distal and proximal fragments. This led to a sensitivity of 1.00 if either cutoff is met and a specificity of 0.82 when both cutoffs are met. Conclusion. Using 3D modelling software, nonunions were found to exhibit bone density increases in both the distal and proximal fragments in CTs performed between four to 18 weeks after fracture during the course of treatment. 2D bone density measurements using standard CT scans correlate well with 3D models. In patients with scaphoid fractures, CT bone density measurements may be useful in predicting the likelihood of nonunion. Cite this article: Bone Joint J 2020;102-B(9):1200–1209

Aims. To evaluate whether an ultra-low-dose CT protocol can diagnose selected limb fractures as well as conventional CT (C-CT). Patients and Methods. We prospectively studied 40 consecutive patients with a limb fracture in whom a CT scan was indicated. These were scanned using an ultra-low-dose CT Reduced Effective Dose Using Computed Tomography In Orthopaedic Injury (REDUCTION) protocol. Studies from 16 selected cases were compared with 16 C-CT scans matched for age, gender and type of fracture. Studies were assessed for diagnosis and image quality. Descriptive and reliability statistics were calculated. The total effective radiation dose for each scanned site was compared. Results. The mean estimated effective dose (ED) for the REDUCTION protocol was 0.03 milliSieverts (mSv) and 0.43 mSv (p < 0.005) for C-CT. The sensitivity (Sn), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) of the REDUCTION protocol to detect fractures were 0.98, 0.89, 0.98 and 0.89 respectively when two occult fractures were excluded. Inter- and intra-observer reliability for diagnosis using the REDUCTION protocol (κ = 0.75, κ = 0.71) were similar to those of C-CT (κ = 0.85, κ = 0.82). Using the REDUCTION protocol, 3D CT reconstructions were equivalent in quality and diagnostic information to those generated by C-CT (κ = 0.87, κ = 0.94). Conclusion. With a near 14-fold reduction in estimated ED compared with C-CT, the REDUCTION protocol reduces the amount of CT radiation substantially without significant diagnostic decay. It produces images that appear to be comparable with those of C-CT for evaluating fractures of the limbs. Cite this article: Bone Joint J 2016;98-B:1668-73

Aims. Besides conventional radiographs, the use of MRI, CT, and bone scintigraphy is frequent in the diagnosis of a fracture of the scaphoid. However, which techniques give the best results remain unknown. The investigation of a new imaging technique initially requires an analysis of its precision. The primary aim of this study was to investigate the interobserver agreement of high-resolution peripheral quantitative CT (HR-pQCT) in the diagnosis of a scaphoid fracture. A secondary aim was to investigate the interobserver agreement for the presence of other fractures and for the classification of scaphoid fracture. Methods. Two radiologists and two orthopaedic trauma surgeons evaluated HR-pQCT scans of 31 patients with a clinically-suspected scaphoid fracture. The observers were asked to determine the presence of a scaphoid or other fracture and to classify the scaphoid fracture based on the Herbert classification system. Fleiss kappa statistics were used to calculate the interobserver agreement for the diagnosis of a fracture. Intraclass correlation coefficients (ICCs) were used to assess the agreement for the classification of scaphoid fracture. Results. A total of nine (29%) scaphoid fractures and 12 (39%) other fractures were diagnosed in 20 patients (65%) using HR-pQCT across the four observers. The interobserver agreement was 91% for the identification of a scaphoid fracture (95% confidence interval (CI) 0.76 to 1.00) and 80% for other fractures (95% CI 0.72 to 0.87). The mean ICC for the classification of a scaphoid fracture in the seven patients diagnosed with scaphoid fracture by all four observers was 73% (95% CI 0.42 to 0.94). Conclusion. We conclude that the diagnosis of scaphoid and other fractures is reliable when using HR-pQCT in patients with a clinically-suspected fracture. Cite this article: Bone Joint J 2020;102-B(4):478–484

Aims. The aims of this study were to determine the indications and frequency of ordering a CT pulmonary angiography (CTPA) following primary arthroplasty of the hip and knee, and to determine the number of positive scans in these patients, the location of emboli and the outcome for patients undergoing CTPA. Patients and Methods. We analyzed the use of CTPA, as an inpatient and up to 90 days as an outpatient, in a cohort of patients and reviewed the medical records and imaging for each patient undergoing CTPA. Results. Out of 11 249 patients, scans were requested in 229 (2.04%) and 86 (38%) were positive. No patient undergoing CTPA died within 90 days. The rate of mortality from pulmonary embolism (PE) overall was 0.08%. CTPA was performed twice as often following total knee arthroplasty (TKA) compared with total hip arthroplasty (THA), and when performed was twice as likely to be positive. Hypoxia was the main indication for a scan, being the indication in 149 scans (65%); and in 23% (11 of 47), the PE was peripheral and unilateral. Three patients suffered complications resulting from therapeutic anticoagulation for possible PE, two of whom had a negative CTPA. Conclusion. CTPA is more likely to be performed following TKA compared with THA. Hypoxia was the main presenting feature of PE. A quarter of PEs which were diagnosed were unilateral and peripheral. Further study may indicate which patients who have a PE after lower limb arthroplasty require treatment, and which can avoid the complications associated with anticoagulation. Cite this article: Bone Joint J 2018;100-B:938–44

The femoral head receives its blood supply primarily from the medial femoral circumflex artery, with its deep branch being the most important. In a previous study, we performed classical anatomical dissections of 16 hips. We have extended our investigation with a radiological study, in which we aimed to visualise the arteries supplying the femoral head in healthy individuals. We analysed 55 CT angiographic images of the hip. Using 64-row CT angiography, we identified three main arteries supplying the femoral head: the deep branch of the medial femoral circumflex artery and the posterior inferior nutrient artery originating from the medial femoral circumflex artery, and the piriformis branch of the inferior gluteal artery. CT angiography is a good method for visualisation of the arteries supplying the femoral head. The current radiological studies will provide information for further investigation of vascularity after traumatic dislocation of the hip, using CT angiography

Aims. The aim of this study was to assess the reproducibility and validity of cross table radiographs for measuring the anteversion of the acetabular component after total hip arthroplasty (THA) and to compare it with measurements using CT scans. Patients and Methods. A total of 29 patients who underwent THA between June 2010 and January 2016 were included. There were 17 men and 12 women. Their mean age was 43 years (26 to 65). Seven patients underwent a bilateral procedure. Thus, 36 THAs were included in the study. Lateral radiographs and CT scans were obtained post-operatively and radiographs repeated three weeks later. The anteversion of the acetabular component was measured using the method described by Woo and Morrey and the ischiolateral method described by Pulos et al and these were compared with the results obtained from CT scans. Results. The mean anteversion was 18.35° (3° to 38°) using Woo and Morrey’s method, 51.45° (30° to 85°) using the ischiolateral method and 21.22° (2° to 48°) using CT scans. The Pearson correlation coefficient was 0.754 for Woo and Morrey’s method and 0.925 for the ischiolateral method. There was a linear correlation between the measurements using the ischiolateral method and those using CT scans. We derived a simple linear equation between the value of the CT scan and that of ischiolateral method to deduce the CT scan value from that of ischiolateral method and vice versa. . Conclusion. The anteversion of the acetabular component measured using both plain radiographic methods was consistently valid with good interobserver reproducibility, but the ischiolateral method which is independent of pelvic tilt was more accurate. As CT is costly, associated with a high dose of radiation and not readily available, the ischiolateral method can be used for assessing the anteversion of the acetabular component. Cite this article: Bone Joint J 2017;99-B:1006–11

Aims. Cone beam CT allows cross-sectional imaging of the tibiofibular syndesmosis while the patient bears weight. This may facilitate more accurate and reliable investigation of injuries to, and reconstruction of, the syndesmosis but normal ranges of measurements are required first. The purpose of this study was to establish: 1) the normal reference measurements of the syndesmosis; 2) if side-to-side variations exist in syndesmotic anatomy; 3) if age affects syndesmotic anatomy; and 4) if the syndesmotic anatomy differs between male and female patients in weight-bearing cone beam CT views. Patients and Methods. A retrospective analysis was undertaken of 50 male and 50 female patients (200 feet) aged 18 years or more, who underwent bilateral, simultaneous imaging of their lower legs while standing in an upright, weight-bearing position in a pedCAT machine between June 2013 and July 2017. At the time of imaging, the mean age of male patients was 47.1 years (18 to 72) and the mean age of female patients was 57.8 years (18 to 83). We employed a previously described technique to obtain six lengths and one angle, as well as calculating three further measurements, to provide information on the relationship between the fibula and tibia with respect to translation and rotation. Results. The upper limit of lateral translation in un-injured patients was 5.27 mm, so values higher than this may be indicative of syndesmotic injury. Anteroposterior translation lay within the ranges 0.31 mm to 2.59 mm, and -1.48 mm to 3.44 mm, respectively. There was no difference between right and left legs. Increasing age was associated with a reduction in lateral translation. The fibulae of men were significantly more laterally translated but data were inconsistent for rotation and anteroposterior translation. Conclusion. We have established normal ranges for measurements in cross-sectional syndesmotic anatomy during weight-bearing and also established that no differences exist between right and left legs in patients without syndesmotic injury. Age and gender do, however, affect the anatomy of the syndesmosis, which should be taken into account at time of assessment. Cite this article: Bone Joint J 2019;101-B:348–352

Aims. Altered alignment and biomechanics are thought to contribute to the progression of osteoarthritis (OA) in the native compartments after medial unicompartmental knee arthroplasty (UKA). The aim of this study was to evaluate the bone activity and remodelling in the lateral tibiofemoral and patellofemoral compartment after medial mobile-bearing UKA. Patients and Methods. In total, 24 patients (nine female, 15 male) with 25 medial Oxford UKAs (13 left, 12 right) were prospectively followed with sequential 99mTc-hydroxymethane diphosphonate single photon emission CT (SPECT)/CT preoperatively and at one and two years postoperatively, along with standard radiographs and clinical outcome scores. The mean patient age was 62 years (40 to 78) and the mean body mass index (BMI) was 29.7 kg/m2 (23.6 to 42.2). Mean osteoblastic activity was evaluated using a tracer localization scheme with volumes of interest (VOIs). Normalized mean tracer values were calculated as the ratio between the mean tracer activity in a VOI and background activity in the femoral diaphysis. Results. Significant reduction of normalized tracer activity was observed one year postoperatively in tibial and femoral VOIs adjacent to the joint line in the lateral compartment. Patellar VOIs and remaining femoral VOIs demonstrated a significant, diminished normalized tracer activity at final follow-up. Conclusion. The osteoblastic bone activity in the native compartments decreased significantly after treatment of medial end-stage OA with a UKA, implying reduced stress to the subchondral bone in the retained compartments after a UKA. Cite this article: Bone Joint J 2019;101-B:915–921

CT arthrography and arthroscopy were used to assess tears of the rotator cuff in 259 shoulders. Tear size was determined in the frontal and sagittal planes according to the classification of the French Arthroscopy Society. CT arthrography had a sensitivity of 99% and a specificity of 100% for the diagnosis of tears of supraspinatus. For infraspinatus these figures were 97.44% and 99.52%, respectively and, for subscapularis, 64.71% and 98.17%. For lesions of the long head of the biceps, the sensitivity was 45.76% and the specificity was 99.57%. Our study showed an excellent correlation between CT arthrography and arthroscopy when assessing the extent of a rotator cuff tear. CT arthrography should, therefore, be an indispensable part of pre-operative assessment. It allows determination of whether a tear is reparable (retraction of the tendon and fatty degeneration of the corresponding muscle) and whether this is possible by arthroscopy (degree of tendon retraction and extension to subscapularis)

Aims. The aim of this study was to analyse the effect of altered viewing perspectives on the measurement of the glenopolar angle (GPA) and the differences between these measurements made on 3D CT reconstructions and anteroposterior (AP) scapular view radiographs. . Materials and Methods. The influence of the viewing perspective on the GPA was assessed, as were the differences in the measurements of the GPA between 3D CT reconstructions and AP scapular view radiographs in 68 cadaveric scapulae. Results. The median GPA in 3D reconstructions and AP scapular views were 42.7° (95% confidence intervals (CI), 42.0° to 43.5°) and 41.3° (95% CI 40.4° to 42.0°) respectively (p < 0.001). All but five of 20 malpositions demonstrated a significant difference in GPA compared with the respective AP scapular view (p ≤ 0.005). The GPA was most susceptible to malposition in retroversion/anteversion. Inter- and intra-observer reliability for all measurements of the GPA was excellent for 3D CT reconstructions (intraclass correlation (ICC) 0.93 (95% CI 0.87 to 0.96) and 0.94 (95% CI 0.89 to 0.97), respectively) and higher than on AP scapular radiographs (p < 0.001). The intra- and inter-observer reliability was excellent in AP scapular views and malpositions in extension/flexion (ICC ≥ 0.84) but tended to decrease with increasing viewing angle in retroversion/anteversion. Conclusion. These data suggest that 3D reconstructions are more reproducible than AP scapular radiographs in the assessment of the GPA and should be used to compare data in different studies, to predict outcome, define malunion, and act as an indication for surgery in patients with a scapular fracture. Cite this article: Bone Joint J 2016;98-B:1510–16

Aims. In this randomized study, we aimed to compare quality of regenerate in monolateral versus circular frame fixation in 30 patients with infected nonunion of tibia. Patients and Methods. Both groups were comparable in demographic and injury characteristics. A phantom (aluminium step wedge of increasing thickness) was designed to compare the density of regenerate on radiographs. A CT scan was performed at three and six months postoperatively to assess regenerate density. A total of 30 patients (29 male, one female; mean age 32.54 years (18 to 60)) with an infected nonunion of a tibial fracture presenting to our tertiary institute between June 2011 and April 2016 were included in the study. Results. The regenerate mineralization on radiographs was comparable in both groups at two, four, six, and ten months’ follow-up but the rail fixator group had statistically significant higher grades of mineralization when compared with the circular frame group at eight and 12 months’ follow-up. The regenerate mineralization was also higher in the rail fixator group than in the circular frame group on CT at three and six months, although this difference was not statistically significant. Conclusion. Overall, the regenerate mineralization was higher in the monolateral than the circular frame group. A monolateral fixator may be preferred in patients with infected nonunion of the tibia with bone defects up to 7 cm. Cite this article: Bone Joint J 2019;101-B:1416–1422

Aims. This prospective randomised controlled trial was designed to evaluate the outcome of both the MRI- and CT-based patient-specific matched guides (PSG) from the same manufacturer. Patients and Methods. A total of 137 knees in 137 patients (50 men, 87 women) were included, 67 in the MRI- and 70 in the CT-based PSG group. Their mean age was 68.4 years (47.0 to 88.9). Outcome was expressed as the biomechanical limb alignment (centre hip-knee-ankle: HKA-axis) achieved post-operatively, the position of the individual components within 3° of the pre-operatively planned alignment, correct planned implant size and operative data (e.g. operating time and blood loss). Results. The patient demographics (e.g. age, body mass index), correct planned implant size and operative data were not significantly different between the two groups. The proportion of outliers in the coronal and sagittal plane ranged from 0% to 21% in both groups. Only the number of outliers for the posterior slope of the tibial component showed a significant difference (p = 0.004) with more outliers in the CT group (n = 9, 13%) than in the MRI group (0%). . Conclusion. The post-operative HKA-axis was comparable in the MRI- and CT-based PSGs, but there were significantly more outliers for the posterior slope in the CT-based PSGs. Take home message: Alignment with MRI-based PSG is at least as good as, if not better, than that of the CT-based PSG, and is the preferred imaging modality when performing TKA with use of PSG. Cite this article: Bone Joint J 2016;98-B:786–92

We studied serial CT scans of 45 arthritic shoulders (34 rheumatoid, 11 osteoarthritic) and 19 normal shoulders, making measurements at three levels on axial images. The maximum anteroposterior diameter of the glenoid was increased in rheumatoid glenoids at the upper and middle levels by 6 mm and in osteoarthritic glenoids at all levels by 5 to 8 mm as compared with normal. In rheumatoid cases, nearly half the available surface of the glenoid was of unsupported bone, mainly posteriorly at the upper and middle levels. In osteoarthritic glenoids, the best supported bone was anterior at the upper level and central at the middle and lower levels. The depth of the rheumatoid glenoid was reduced by a mean of 6 mm at the upper and middle levels and by 3 mm at the lower level. This inclined the surface of the glenoid superiorly. The depth at the middle level in osteoarthritis was reduced by a mean of 5 mm, suggesting central protrusion. Osteoarthritic glenoids were retroverted by a mean of 12.5 degrees, but of rheumatoid glenoids two-thirds were retroverted (mean 15.1 degrees) and one-third anteverted (mean 8.2 degrees). Our findings have important implications for the planning and placement of the glenoid component of total shoulder replacements; CT can provide useful information

The aim of this study was to find anatomical landmarks for rotational alignment of the tibial component in total knee replacement (TKR) in a CT-based study. Pre-operative CT scanning was performed on 94 South Korean patients (nine men, 85 women, 188 knees) with osteoarthritis of the knee joint prior to TKR. The tibial anteroposterior (AP) axis was defined as a line perpendicular to the femoral surgical transepicondylar axis and passing through the centre of the posterior cruciate ligament (PCL). The angles between the defined tibial AP axis and anatomical landmarks at various levels of the tibia were measured. The mean values of the angles between the defined tibial AP axis and the line connecting the anterior border of the proximal third of the tibia to the centre of the PCL was -0.2° (-17 to 14.1, . sd. 4.1). This was very close to the defined tibial axis, and remained so regardless of lower limb alignment and the degree of tibial bowing. Therefore, AP axis defined as described, is a reliable anatomical landmark for rotational alignment of tibial components. Cite this article: Bone Joint J 2014; 96-B:1485–90

We reviewed radiographs and CT scans of 38 total hip arthroplasties which had dislocated (36 posteriorly; 2 anteriorly) and compared the alignment of the prosthetic components with those of 14 uncomplicated arthroplasties. No difference was found between the alignment of the prosthetic components in the two groups. In the seven patients who had reoperations, the cause of dislocation diagnosed by CT was confirmed in only two cases (one retroversion of the cup and one protruding osteophyte). Muscular imbalance rather than malposition of the components was the major factor determining dislocation. CT allows accurate measurement of cup and neck anteversion but contributes little to preoperative planning

Computed tomography was performed on 40 patients with recent hip trauma. Radiographs of 25 showed a fracture of the femoral neck with slight displacement; 24 of these had intra-articular fluid and 20 had a lipohaemarthrosis on the CT scan. In 15 patients, radiographs at the time of admission were normal but suspicion of fracture remained. A fracture was later verified in five patients, four of whom had lipohaemarthrosis on admission. In the remaining 10 patients no fracture could be detected; only one patient had a hip joint effusion but no free fat. Thus all 24 patients with lipohaemarthrosis had an intracapsular fracture of the hip. We suggest CT for patients with hip trauma and negative radiographs. The presence of a lipohaemarthrosis of the hip strongly suggests an intra-articular fracture of either the femoral neck or the acetabulum

Distal tibial physeal fractures are the second most common growth plate injury and the most common cause of growth arrest and deformity. This study assesses the accuracy of pre-operative planning for placement of the screws in these fractures using either standard radiographs or CT scans. We studied 62 consecutive physeal fractures over a period of four years. An outline of a single cut of the CT scan was used for each patient. An ideal position for the screw was determined as being perpendicular to and at the midpoint of the fracture. The difference in entry point and direction of the screw between the ideal and the observers’ assessments were compared using the paired Student’s t-test. There was a statistically significant improvement (p < 0.0001) in the accuracy of the point of insertion and the direction of the screw on the pre-operative plan when CT scans were used rather than plain radiographs. We would, therefore, recommend that CT scans are routinely used in the pre-operative assessment and treatment of distal tibial physeal fractures

We investigated the development of CT-based bony radiological parameters associated with femoroacetabular impingement (FAI) in a paediatric and adolescent population with no known orthopaedic hip complaints. We retrospectively reformatted and reoriented 225 abdominal CTs into standardised CT pelvic images with neutral pelvic tilt and inclination (244 female and 206 male hips) in patients ranging from two to 19 years of age (mean 10.4 years). The Tönnis angle, acetabular depth ratio, lateral centre–edge angle, acetabular version and α-angle were assessed. Acetabular measurements demonstrated increased acetabular coverage with age and/or progressive ossification of the acetabulum. The α-angle decreased with age and/or progressive cortical bone development and resultant narrowing of the femoral neck. Cam and pincer morphology occurred as early as ten and 12 years of age, respectively, and their prevalence in the adolescent patient population is similar to that reported in the adult literature. Future aetiological studies of FAI will need to focus on the early adolescent population. Cite this article: Bone Joint J 2013;95-B:598–604

The nerve roots of the cauda equina may be visualised by contrast-enhanced CT scans and by surface-coil MRI. We have identified the pattern of anatomy from L2-L3 to L5-S1 in 10 human cadaver specimens and correlated this with anatomical dissections. Individual roots are slightly more distinct on contrast-enhanced CT than on surface-coil MRI. There is a crescentic oblique pattern of nerve roots at the lower lumbar levels which is still apparent in the more crowded proximal sections. In all cases, the axial images correlated precisely with the dissections. Current imaging modalities can help the clinical understanding and management of abnormalities in this region of the spine

We hypothesised that the use of pulsed electromagnetic field (PEMF) bone growth stimulation in acute scaphoid fractures would significantly shorten the time to union and reduce the number of nonunions in a randomised, double-blind, placebo-controlled multicentre trial. A total of 102 patients (78 male, 24 female; mean age 35 years (18 to 77)) from five different medical centres with a unilateral undisplaced acute scaphoid fracture were randomly allocated to PEMF (n = 51) or placebo (n = 51) and assessed with regard to functional and radiological outcomes (multiplanar reconstructed CT scans) at 6, 9, 12, 24 and 52 weeks. The overall time to clinical and radiological healing did not differ significantly between the active PEMF group and the placebo group. We concluded that the addition of PEMF bone growth stimulation to the conservative treatment of acute scaphoid fractures does not accelerate bone healing. Cite this article: Bone Joint J 2014; 96-B:1070–6

We evaluated the impact of stereo-visualisation of three-dimensional volume-rendering CT datasets on the inter- and intraobserver reliability assessed by kappa values on the AO/OTA and Neer classifications in the assessment of proximal humeral fractures. Four independent observers classified 40 fractures according to the AO/OTA and Neer classifications using plain radiographs, two-dimensional CT scans and with stereo-visualised three-dimensional volume-rendering reconstructions. Both classification systems showed moderate interobserver reliability with plain radiographs and two-dimensional CT scans. Three-dimensional volume-rendered CT scans improved the interobserver reliability of both systems to good. Intraobserver reliability was moderate for both classifications when assessed by plain radiographs. Stereo visualisation of three-dimensional volume rendering improved intraobserver reliability to good for the AO/OTA method and to excellent for the Neer classification. These data support our opinion that stereo visualisation of three-dimensional volume-rendering datasets is of value when analysing and classifying complex fractures of the proximal humerus

Using a modern cementing technique, we implanted 22 stereolithographic polymeric replicas of the Charnley-Kerboul stem in 11 pairs of human cadaver femora. On one side, the replicas were cemented line-to-line with the largest broach. On the other, one-size undersized replicas were used (radial difference, 0.89 mm . sd. 0.13). CT analysis showed that the line-to-line stems without distal centralisers were at least as well aligned and centered as undersized stems with a centraliser, but were surrounded by less cement and presented more areas of thin (< 2 mm) or deficient (< 1 mm) cement. These areas were located predominantly at the corners and in the middle and distal thirds of the stem. Nevertheless, in line-to-line stems, penetration of cement into cancellous bone resulted in a mean thickness of cement of 3.1 mm (. sd. 0.6) and only 6.2% of deficient and 26.4% of thin cement. In over 90% of these areas, the cement was directly supported by cortical bone or cortical bone with less than 1 mm of cancellous bone interposed. When Charnley-Kerboul stems are cemented line-to-line, good clinical results are observed because cement-deficient areas are limited and are frequently supported by cortical bone

We have previously described a simple and reproducible three-dimensional technique of CT for the measurement of the cover of the femoral head in acetabular dysplasia in adults. We now describe the application of this technique in ten patients with symptomatic dysplasia to assess the degree and direction of dysplasia and to measure the cover obtained at acetabular osteotomy. The indices obtained gave a useful indication of the degree and direction of the dysplasia and confirmed which components had been used most efficiently to achieve cover. The information is easily presented in graphical form and gives a clearer indication of the cover obtained than the indices derived from plain radiographs

This study examined the relationship between the cross-over sign and the true three-dimensional anatomical version of the acetabulum. We also investigated whether in true retroversion there is excessive femoral head cover anteriorly. Radiographs of 64 hips in patients being investigated for symptoms of femoro-acetabular impingement were analysed and the presence of a cross-over sign was documented. CT scans of the same hips were analysed to determine anatomical version and femoral head cover in relation to the anterior pelvic plane after correcting for pelvic tilt. The sensitivity and specificity of the cross-over sign were 92% and 55%, respectively for identifying true acetabular retroversion. There was no significant difference in total cover between normal and retroverted cases. Anterior and posterior cover were, however, significantly different (p < 0.001 and 0.002). The cross-over sign was found to be sensitive but not specific. The results for femoral head cover suggest that retroversion is characterised by posterior deficiency but increased cover anteriorly

Teratomas in the spinal cord are rare. We report a case in a 54-year-old man. CT scans revealed tumours of different densities within the spinal canal; this heterogeneity may help to differentiate teratoma from other spinal cord tumours. After resection of the tumours under microscopy, the result was excellent. Histological examination showed a variety of tissues, including elements of all three germinal layers

Two different classifications of discograms have been used in a prospective study of 279 injected discs in 100 patients. The five-stage classification of Adams, Dolan and Hutton (1986) showed increased degeneration in the lower lumbar discs and more degenerative changes in men than in women. Exact reproduction of the patient's pain on injection was more common in fissured or ruptured discs than in less degenerate discs, with 81% sensitivity and 64% specificity of the discogram for pain. The additional information obtained by comparing computerised tomography (CT) with discograms was minimal. Discography was found to be useful in the evaluation of chronic low back pain in patients whose ordinary CT scans, myelograms and flexion-extension radiographs were normal. In spondylolysis and spondylolisthesis, discography can disclose whether fusion needs to be extended above the lytic level, and it may show if the pain in patients who have had posterolateral fusion is discogenic. Thus, discography gives information which is useful in deciding whether to operate on patients with chronic low back pain

Techniques are described by which metal implants can be designed and produced to fit precisely a bony site at a subsequent operation. CT scans and solid modelling were used to produce an accurate three-dimensional representation of the surface of the bone. These techniques were applied to the production of an internal fixation device for shoulder arthrodesis after the resection of a neoplasm of the proximal humerus. The reconstruction utilised a free vascularised fibular graft between the scapula and the distal humeral remnant, fixation being secured with the custom-made implant

Ventral screw osteosynthesis is a common surgical method for treating fractures of the odontoid peg, but there is still no consensus about the number and diameter of the screws to be used. The purpose of this study was to develop a more accurate measurement technique for the morphometry of the odontoid peg (dens axis) and to provide a recommendation for ventral screw osteosynthesis.

Images of the cervical spine of 44 Caucasian patients, taken with a 64-line CT scanner, were evaluated using the measuring software MIMICS. All measurements were performed by two independent observers. Intraclass correlation coefficients were used to measure inter-rater variability.

The mean length of the odontoid peg was 39.76 mm (sd 2.68). The mean screw entry angle α was 59.45° (sd 3.45). The mean angle between the screw and the ventral border of C2 was 13.18° (sd 2.70), the maximum possible mean converging angle of two screws was 20.35° (sd 3.24). The measurements were obtained at the level of 66% of the total odontoid peg length and showed mean values of 8.36 mm (sd 0.84) for the inner diameter in the sagittal plane and 7.35 mm (sd 0.97) in the coronal plane. The mean outer diameter of the odontoid peg was 12.88 mm (sd 0.91) in the sagittal plane and 11.77 mm (sd 1.09) in the coronal plane. The results measured at the level of 90% of the total odontoid peg length were a mean of 6.12 mm (sd 1.14) for the sagittal inner diameter and 5.50 mm (sd 1.05) for the coronal inner diameter. The mean outer diameter of the odontoid peg was 11.10 mm (sd 1.0) in the sagittal plane and 10.00 mm (sd 1.07) in the coronal plane. In order to calculate the necessary screw length using 3.5 mm cannulated screws, 1.5 mm should be added to the measured odontoid peg length when anatomical reduction seems possible.

The cross-section of the odontoid peg is not circular but slightly elliptical, with a 10% greater diameter in the sagittal plane. In the majority of cases (70.5%) the odontoid peg offers enough room for two 3.5 mm cannulated cortical screws.

Cite this article: Bone Joint J 2013;95-B:536–42.

We performed a prospective study to examine the influence of the patient’s position on the location of the abdominal organs, to investigate the possibility of a true lateral approach for transforaminal endoscopic lumbar discectomy. Pre-operative abdominal CT scans were taken in 20 patients who underwent endoscopic lumbar discectomy. Axial images in parallel planes of each intervertebral disc from L1 to L5 were achieved in both supine and prone positions. The most horizontal approach angles possible to avoid injury to the abdominal organs were measured. The results demonstrated that the safe approach angles were significantly less (i.e., more horizontal) in the prone than in the supine position. Obstacles to a more lateral approach were mainly the liver, the spleen and the kidneys at L1/2 (39 of 40, 97.5%) and L2/3 (28 of 40, 70.0%), and the intestines at L3/4 (33 of 40, 82.5%) and L4/5 (30 of 30, 100%). A true lateral approach from each side was possible for 30 of the 40 discs at L3/4 (75%) and 23 of the 30 discs at L4/5 (76.7%). We concluded that a more horizontal approach for transforaminal endoscopic lumbar discectomy is possible in the prone position but not in the supine. Prone abdominal CT is more helpful in determining the trajectory of the endoscope. While a true lateral approach is feasible in many patients, our study shows it is not universally applicable.

In 139 patients with burst fractures of the thoracic, thoracolumbar or lumbar spine, the least sagittal diameter of the spinal canal at the level of injury was measured by computerised tomography. By multiple logistic regression we investigated the joint correlation of the level of the burst fracture and the percentage of spinal canal stenosis with the probability of an associated neurological deficit. There was a very significant correlation between neurological deficit and the percentage of spinal canal stenosis; the higher the level of injury the greater was the probability. The severity of neurological deficit could not be predicted.

Aims. Complex elbow fracture-dislocations often result in suboptimal outcomes and necessitate a thorough understanding of injury patterns to guide effective management and reduce adverse sequelae. The Wrightington Classification System (WCS) offers a comprehensive approach and considers both bony and soft-tissue disruption, providing clearer guidance for treatment. This is the first external study to assess the reliability of the WCS for elbow fracture-dislocations. Methods. A blinded study of patients with elbow fracture-dislocations at a single institution between December 2014 and December 2022 was conducted. Five assessors with a range of experience, including orthopaedic surgeons and radiologists, independently classified injuries using the WCS across three image methods: plain radiograph, 2D CT, and 2D and 3D CT reconstruction images, on two occasions with an eight-week interval. Interobserver and intraobserver reliability were evaluated using kappa statistics and the Landis and Koch criteria. Results. A total of 73 patients were included in the study. Interobserver reliability was moderate, with mean kappa values of 0.518 (95% CI 0.499 to 0.537), 0.557 (95% CI 0.537 to 0.577), and 0.582 (95% CI 0.562 to 0.601), for radiographs, 2D CT, and 2D and 3D CT reconstructions, respectively. Intraobserver agreement was substantial (mean kappa 0.695 (SE 0.067), 0.729 (SE 0.071), and 0.777 (SE 0.070) for radiographs, 2D CT, and 3D CT reconstructions, respectively). Conclusion. The WCS is a reliable and valuable tool for characterizing elbow fracture-dislocations and guiding surgical interventions. This study found moderate reliability in using the WCS, with higher reliability with combined 2D and 3D CT imaging. Further refinement within the WCS in differentiating between coronoid avulsions, basal, anteromedial, and/or anterolateral facet injuries may help improve reliability and reproducibility. Cite this article: Bone Joint J 2025;107-B(2):188–192

Aims. Mechanical impingement of the iliopsoas (IP) tendon accounts for 2% to 6% of persistent postoperative pain after total hip arthroplasty (THA). The most common initiator is anterior acetabular component protrusion, where the anterior margin is not covered by anterior acetabular wall. A CT scan can be used to identify and measure this overhang; however, no threshold exists for determining symptomatic anterior IP impingement due to overhang. A case-control study was conducted in which CT scan measurements were used to define a threshold that differentiates patients with IP impingement from asymptomatic patients after THA. Methods. We analyzed the CT scans of 622 patients (758 THAs) between May 2011 and May 2020. From this population, we identified 136 patients with symptoms suggestive of IP impingement. Among them, six were subsequently excluded: three because the diagnosis was refuted intraoperatively, and three because they had another obvious cause of impingement, leaving 130 hips (130 patients) in the study (impingement) group. They were matched to a control group of 138 asymptomatic hips (138 patients) after THA. The anterior acetabular component overhang was measured on an axial CT slice based on anatomical landmarks (orthogonal to the pelvic axis). Results. The impingement group had a median overhang of 8 mm (interquartile range (IQR) 5 to 11) versus 0 mm (IQR 0 to 4) for the control group (p < 0.001). Using receiver operating characteristic curves, an overhang threshold of 4 mm was best correlated with a diagnosis of impingement (sensitivity 79%, specificity 85%; positive predictive value 75%, negative predictive value 85%). Conclusion. Pain after THA related to IP impingement can be reasonably linked to acetabular overhang if it exceeds 4 mm on a CT scan. Below this threshold, it seems logical to look for another cause of IP irritation or another reason for the pain after THA before concluding that impingement is present. Cite this article: Bone Joint J 2024;106-B(3 Supple A):97–103

Aims. The purpose of this study was to assess the success rate and functional outcomes of bone grafting for periprosthetic bone cysts following total ankle arthroplasty (TAA). Additionally, we evaluated the rate of graft incorporation and identified associated predisposing factors using CT scan. Methods. We reviewed a total of 37 ankles (34 patients) that had undergone bone grafting for periprosthetic bone cysts. A CT scan was performed one year after bone grafting to check the status of graft incorporation. For accurate analysis of cyst volumes and their postoperative changes, 3D-reconstructed CT scan processed with 3D software was used. For functional outcomes, variables such as the Ankle Osteoarthritis Scale score and the visual analogue scale for pain were measured. Results. Out of 37 ankles, graft incorporation was successful in 30 cases. Among the remaining seven cases, four (10.8%) exhibited cyst re-progression, so secondary bone grafting was needed. After secondary bone grafting, no further progression has been noted, resulting in an overall 91.9% success rate (34 of 37) at a mean follow-up period of 47.5 months (24 to 120). The remaining three cases (8.1%) showed implant loosening, so tibiotalocalcaneal arthrodesis was performed. Functional outcomes were also improved after bone grafting in all variables at the latest follow-up (p < 0.05). The mean incorporation rate of the grafts according to the location of the cysts was 84.8% (55.2% to 96.1%) at the medial malleolus, 65.1% (27.6% to 97.1%) at the tibia, and 81.2% (42.8% to 98.7%) at the talus. Smoking was identified as a significant predisposing factor adversely affecting graft incorporation (p = 0.001). Conclusion. Bone grafting for periprosthetic bone cysts following primary TAA is a reliable procedure with a satisfactory success rate and functional outcomes. Regular follow-up, including CT scan, is important for the detection of cyst re-progression to prevent implant loosening after bone grafting. Cite this article: Bone Joint J 2024;106-B(5):475–481

Aims. Loosening of the glenoid component in the long term remains an important complication of the anatomical total shoulder arthroplasty (aTSA). The aim of this study was to explore the bony integration of a hybrid glenoid component based on an analysis of CT scans. Methods. In a prospective multicentre study, patients who underwent primary aTSA, whose hybrid design of glenoid component included a fully-polyethylene flanged upper peg and a porous-coated titanium lower peg, and who were reviewed with CT scans between 12 and 24 months postoperatively, were included. Two independent observers reviewed the scans. Bony integration of the upper peg was scored as described by Arnold et al, and integration of the lower peg was scored as described by Gulotta et al. Perforation of the glenoid vault in any plane was also assessed. Results. From an initial group of 120 aTSAs in 116 patients, 104 CT scans were analyzed in 100 patients (four bilateral shoulders, mean age 66 years (SD 11), 62 female and 38 male). Osteolysis around the upper peg was found in 32 patients (32 aTSAs; 31%). Of the remaining patients, 72 had a mean Arnold score of 5.6 points (SD 0.9), and 70 (67%) had perfect integration. The lower peg had a mean Gulotta score of 6.5 points (SD 1.4). There was perfect integration of the lower peg in 70 patients (70 aTSAs; 67%). A total of nine patients (nine aTSAs; 9%) had no bony integration at either peg. There was perforation of the glenoid in an anterior or posterior direction at the level of the upper peg in three and 28 patients, respectively. This occurred at the level of the lower peg in 11 and 18 patients, respectively. The inter- and intraobserver reliability was good (k = 0.782 and 0.86, respectively). No implant breakage occurred at a mean follow-up of 16 months (12 to 24). The clinical outcome was satisfactory at a mean follow-up of 32 months (24 to 35), as assessed by a visual analogue scale score for pain, the Constant-Murley score, Subjective Shoulder Value, and American Shoulder and Elbow Surgeons score. Conclusion. Short-term CT scan analysis of a new hybrid anatomical glenoid component found perfect bony integration around the lower porous coated titanium peg in 90% of patients. The upper polyethylene flanged peg had bony integration in 70 patients (70 aTSAs; 67%). Longer follow-up is needed to analyze the rate of survival of this component. The short-term clinical outcome was satisfactory. Cite this article: Bone Joint J 2025;107-B(2):181–187

Aims. The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants. Methods. A consecutive series of 45 (2014 to 2019) PPRs for Paprosky III defects at rTHA were analyzed comparing the preoperative planning CT scans used to manufacture the implants with postoperative CT scans and radiographs. The anteversion (AV), inclination (IC), deviation from the preoperatively planned implant position, and deviation of the centre of rotation (COR) were explored. Early postoperative complications were recorded, and factors for malpositioning were sought. The mean follow-up was 30 months (SD 19; 6 to 74), with four patients lost to follow-up. Results. Mean CT defined discrepancy (Δ) between planned and achieved AV and IC was 4.5° (SD 3°; 0° to 12°) and 4° (SD 3.5°; 1° to 12°), respectively. Malpositioning (Δ > 10°) occurred in five hips (10.6%). Native COR reconstruction was planned in 42 cases (93%), and the mean 3D deviation vector was 15.5 mm (SD 8.5; 4 to 35). There was no significant influence in malpositioning found for femoral stem retention, surgical approach, or fixation method. Conclusion. At short-term follow-up, we found that PPR offers a viable solution for rTHA in cases with massive acetabular bone loss, as highly accurate positioning can be accomplished with meticulous planning, achieving anatomical reconstruction. Accuracy of achieved placement contributed to reduced complications with no injury to vital structures by screw fixation. Cite this article: Bone Joint J 2022;104-B(10):1110–1117