We aim to assess the value of patellofemoral Computed Tomography in assessing patients with anterior knee symptoms. Anterior knee symptoms are often due to patellar malalignment. Plain axial radiography or (CT) can be used to investigate these abnormalities. We have evaluated the use of patellofemoral CT scanning in 63 patients and compared the CT findings with the patients’ symptoms. We compared patellar centralisation and patellar tilt angle with the symptom described for each of 126 knees. No difference could be detected in the CT appearances of affected and unaffected knees in those patients with unilateral symptoms (all patients have both knees scanned). A significant association between maltracking and osteoarthiritic changes was demonstrated

Aim of the study: To define the dimensions of the radial head, as well as the radiocapitellar and proximal radio-ulnar joints. The most congruent portions of the radial head articulations were determined. Materials & Methods: Computed tomography scans of twenty-two cadaveric adult elbows were obtained in three forearm positions – supination, neutral, pronation. The radial head dimensions, the radiocapitellar joints, and the proximal radioulnar joints were also measured. Multivariate analysis of variance was used to determine which portions of each articulation were the most congruent. Results: At the level of the radial trough, the maximum diameter was 22.3 mm, the minimum diameter was 20.9 mm, and the diameter difference was 1.4 mm. This difference represented only 6.3% of the overall maximum diameter. The depth of curvature of the radial head trough was 2.3 mm, the radial head length was 9.8 mm, and the radial neck length was 10.7 mm. At the isthmus of medullary canal, the maximum diameter was 9.7 mm, the minimum diameter was 8.2 mm, and the diameter difference was 1.5 mm. This difference represented 15.6% of the maximum diameter. The average radiocapitellar distance at the radial lip was 4.0 mm, the trough 2.4 mm, and the ulnar lip 2.2 mm. Thus, the radial head tended to become uncovered at the radial lip (p < 0.0001). The radiocapitellar joint was tighter in pronation than in supination (p = 0.0008). The proximal radioulnar joint was most congruent at the MPRUJ (middle proximal radioulnar joint), at the midportion and posterior aspects, rather than the anterior aspect (p < 0.0001). The PRUJ coverage was between 69.0 and 79.2 degrees. Conclusions: Prosthesis trial sizing should be judged by the articulations providing the most congruency –. 1) the ulnar lip or trough of the radiocapitellar joint in pronation and. 2) the posterior or midportion of the MRPUJ

Purpose: We analysed outcome of 106 Latarjet-Patte procedures at 7.5 years mean follow-up. Computed tomography of 80 bone blocks provided further details. Material and methods: One hundred two patients (106 bone blocks), mean age 34 years, were reviewed at a mean 7.5 years follow-up. The sex ratio was 5/1 M/F. The accident had occurred at a mean age of 22 years, by trauma in 87% of the cases, generally involving the dominant limb. Eighty-seven patients practised sports, a high-risk sport in 48% of the cases. Clinical outcome was assessed with the Duplay and Row score, radiographs and a bilateral computed tomography scan in 80 cases. Results: Postoperative morbidity was 12% and only required revision surgery in 2.8% of the cases. Posterior pain required screw ablation in 6% of the cases. Global outcome was excellent or good in 66% of the patients and 60% of the patients who practised sports were able to resume their activities at the same level. Painless shoulders were achieved for 70% of the patients. There was one post-traumatic recurrence and residual apprehension in 13% of the cases. Grade 3 or 3 osteoarthritis was present in 15% of the cases with a clear narrowing of the joint space in 3.5%. The CT scans were less favourable, showing global or posterior joint space narrowing in 17.5% of the cases. Monocortical screwing led to nonunion in 7%. Advanced osteolysis led to pain with alteration of the functional score. Discussion: Postoperative complications deteriorated the global result. Overly long malleolar screws led to posterior pain with fatty degeneration of the infraspinatus. Osteoarthritis and “inverted L” subscapularis were the main factors related to loss of rotation. Persistent apprehension was not related to technical error, but to exaggerated anteversion of the humeral cap, basically due to the presence of a notch. Revision scans clearly contributed to the evaluation of the bone block and its position. It allowed a more objective assessment of the osteoarthritis, showing that plain radiographs underestimated both incidence and gravity related to delay after surgery, patient age and the overhanging property of the joint stop. Conclusion: The Latarjet-Patte procedure has given satisfactory results that can be improved with rigorous technique. Computed tomography provides a more objective analysis of the results

Normal acetabular development in developmental dysplasia of the hip (DDH) depends upon early and maintained congruent reduction. Computed tomography is an accepted method for evaluating this and attempts to quantify hip reduction, by various angular and linear measurements, have been reported. The aim of this study was to assess initial CT scans, following open reduction in the older child with DDH, with comparison of outcome to evaluate prognostic value. Method: Thirty consecutive patients underwent open reduction for DDH, with a mean age of 25.9 months at the time of operation. Acetabular morphology and the position of the femoral head were evaluated on the initial CT scan, taken on the first postoperative day, and AP pelvic radiograph taken at the latest follow-up. Results: The acetabulae of the dislocated hips were found to be significantly more anteverted than the normal. The dislocated hips also had significantly increased lateral displacement both initially and at latest follow-up. Posterior displacement of the proximal femoral metaphysis should raise concern due to an association with the need for further surgical intervention. These results did not however correlate with outcome. In conclusion, despite the significant differences noted between DDH and normal hips they did not predict acetabular development or persistent acetabular dysplasia

A primary goal of revision Total Knee Arthroplasty (rTKA) is restoration of the Joint Line (JL) and Posterior Condylar Offsets (PCO). The presence of a native contralateral joint allows JL and PCO to be inferred in a way that could account for patient-specific anatomical variations more accurately than current techniques. This study assesses bilateral distal femoral symmetry in the context of defining targets for restoration of JL and PCO in rTKA.

566 pre-operative CTs for bilateral TKAs were segmented and landmarked by two engineers. Landmarks were taken on both femurs at the medial and lateral epicondyles, distal and posterior condyles and hip and femoral centres. These landmarks were used to calculate the distal and posterior offsets on the medial and lateral sides (MDO, MPO, LDO, LPO respectively), the lateral distal femoral angle (LDFA), TEA to PCA angle (TEAtoPCA) and anatomic to mechanical axis angle (AAtoMA). Mean bilateral differences in these measures were calculated and cases were categorised according to the amount of asymmetry.

The database analysed included 54.9% (311) females with a mean population age of 68.8 (±7.8) years. The mean bilateral difference for each measure was: LDFA 1.4° (±1.0), TEAtoPCA 1.3° (±0.9), AAtoMA 0.5° (±0.5), MDO 1.4mm (±1.1), MPO 1.0mm (±0.8). The categorisation of asymmetry for each measure was: LDFA had 39.9% of cases with <1° bilateral difference and 92.4% with <3° bilateral difference, TEAtoPCA had 45.8% <1° and 96.6% <3°, AAtoMA had 85.7% <1° and 99.8% <3°, MDO had 46.2% <1mm and 90.3% <3mm, MPO had 57.0% <1mm and 97.9% <3mm.

This study presents evidence supporting bilateral distal femoral symmetry. Using the contralateral anatomy to obtain estimates for JL and PCO in rTKA may result in improvements in intraoperative accuracy compared to current techniques and a more patient specific solution to operative planning.

Analyzing shoulder kinematics is challenging as the shoulder is comprised of a complex group of multiple highly mobile joints. Unlike at the elbow or knee which has a primary flexion/extension axis, both primary shoulder joints (glenohumeral and scapulothoracic) have a large range of motion (ROM) in all three directions. As such, there are six degrees of freedom (DoF) in the shoulder joints (three translations and three rotations), and all these parameters need to be defined to fully describe shoulder motion. Despite the importance of glenohumeral and scapulothoracic coordination, it's the glenohumeral joint that is most studied in the shoulder. Additionally, the limited research on the scapulothoracic primarily focuses on planar motion such as abduction or flexion. However, more complex motions, such as internally rotating to the back, are rarely studied despite the importance for activities of daily living. A technique for analyzing shoulder kinematics which uses 4DCT has been developed and validated and will be used to conduct analysis. The objective of this study is to characterize glenohumeral and scapulothoracic motion during active internal rotation to the back, in a healthy young population, using a novel 4DCT approach.

Eight male participants over 18 with a healthy shoulder ROM were recruited. For the dynamic scan, participants performed internal rotation to the back. For this motion, the hand starts on the abdomen and is moved around the torso up the back as far as possible, unconstrained to examine variability in motion pathway. Bone models were made from the dynamic scans and registered to neutral models, from a static scan, to calculate six DoF kinematics. The resultant kinematic pathways measured over the entire motion were used to calculate the ROM for each DoF.

Results indicate that anterior tilting is the most important DoF of the scapula, the participants all followed similar paths with low variation. Conversely, it appears that protraction/retraction of the scapula is not as important for internally rotating to the back; not only was the ROM the lowest, but the pathways had the highest variation between participants. Regarding glenohumeral motion, internal rotation was by far the DoF with the highest ROM, but there was also high variation in the pathways. Summation of ROM values revealed an average glenohumeral to scapulothoracic ratio of 1.8:1, closely matching the common 2:1 ratio other studies have measured during abduction.

Due to the unconstrained nature of the motion, the complex relationship between the glenohumeral and scapulothoracic joints leads to high variation in kinematic pathways. The shoulder has redundant degrees of freedom, the same end position can result from different joint angles and positions. Therefore, some individuals might rely more on scapular motion while others might utilize primarily humeral motion to achieve a specific movement. More analysis needs to be done to identify if any direct correlations can be drawn between scapulothoracic and glenohumeral DoF. Analyzing the kinematics of the glenohumeral and scapulothoracic joint throughout motion will further improve understanding of shoulder mechanics and future work plans to examine differences with age.

Summary Statement. It is now possible to diagnose osteoporosis using incidental abdominal CT scans; applying this approach to fractures of the cervical spine demonstrates levels of osteoporosis in patients over 65. Introduction. Recently published data now makes it possible to screen for osteoporosis in patients who, in the course of their hospital stay, have had Computed Tomography (CT) scans of their abdomen for reasons other than direct imaging. This is as a result of CT derived bone mineral density (BMD) in the first lumbar vertebra (L1) being correlated BMD derived from Dual-energy X-ray absorptiometry (DEXA) scans. The advantage of this is the reduction in both cost and radiation exposure. Although age has a detrimental effect on BMD, relatively few patients have formal DEXA studies. The aims of this study were to evaluate the utility of this new technique in a cohort of patients with acute fractures of the cervical spine and to compare relative values for BMD in patients aged over 65 with those aged under 65, and thus define the role of osteoporosis in these injuries. Methods & Patients. Following Institutional review board approval, we performed a retrospective study of patients who presented to a level I trauma center with acute fractures of the cervical spine between 2010 and 2013; patients also had to have had a CT scan of their L1 vertebra either during the admission or within 6 months of their admission (for any other clinical reason). Using a picture archiving and communication (PACS) system, we generated regions of interest (ROI) of similar size in the body of L1 (excluding the cortex), in line with the publication by Pickhardt et al., and computed the mean values for Hounsfield units (HU). These values were compared against established threshold values which differentiate between osteoporosis and osteopenia; for a balanced sensitivity and specificity, <135 HU is the threshold and for 90% sensitivity a HU threshold of <160 HU is set. Comparisons were also performed between age stratified groups. Results. A total of 187 patients were reviewed for eligibility, 91 patients met the criteria with 53 patients aged 64 years or younger (range 23–64) and 38 patients aged above 65 years (range 65–98). In the younger cohort, 6/53 (11% were osteoporotic, using the lower threshold, while the higher threshold indicated 5/53 (17%) of patients under 65 years were osteoporotic; mean HU for the group was 195.8 (SD 43.3). In the older cohort, 24/38 (63%) were osteoporotic using the lower threshold, whereas 34/38 (89%) were osteoporotic using the higher threshold. Mean HU for the cohort aged over 65 years was 118.7 (SD 38.4). Age based comparison of the mean values, regardless of threshold, was statistically significant (p<0.001) in both cases. Discussion and Conclusions. This study demonstrates, for the first time in the cervical spine (including C2), the role of age related osteoporosis in acute fractures of the cervical spine. This new technique harnessing the presence of opportunistic CT scans of the abdomen saves on the extra cost and radiation exposure that may be associated with DEXA scanning. In younger patients, the higher threshold indicated 17% were osteoporotic – in the setting of an opportunistic scan, this may afford them the opportunity to commence prophylactic treatment to prevent future fractures. We believe these result have the potential to significantly impact future clinical practice

Our aim was to use CT Scanogram to evaluate fibular growth, and thus calculate normal growth velocity, which may aid in determining the timing of epiphysiodesis. Current understanding of normal lower limb growth and growth prediction originates in the work of Anderson et al published in the 1960s. There now exist several clinical and mathematical methods to aid in the treatment of leg length discrepancy, including the timing of epiphysiodesis. Early research in this area provided limited information on the growth of the fibula. It is now well recognized that abnormal growth of paired long bones may evolve into deformity of clinical significance. Existing work examining fibular growth used plain film radiography only. Computed Tomography (CT) scanogram is now the preferred method for evaluating leg length discrepancy in the paediatric population. We calculated fibular growth for 28 children (n = 28, 16 girls and 12 boys) presenting with leg length discrepancy to our unit. Mean age at presentation was 111.1 months (range 33 – 155 months). For inclusion, each child had to have at least five CT scanograms performed, at six monthly intervals. Fibular length was calculated digitally as the distance from the proximal edge of the proximal epiphysis to the most distal edge of the distal epiphysis. For calculation purposes, mean fibular length was determined from two measurements taken of the fibula. A graph for annual fibular growth was plotted and fibular growth velocity calculated. CT Scanogram may be used to calculate normal fibular growth in children presenting with leg length discrepancy

Summary Statement. Using abdominal CT scans to evaluate bone mineral density following acute fractures of the thoracic and lumbar spine demonstrates significant levels of osteoporosis in older patients; this approach may help save on time and resources, and reduce unnecessary radiation exposure. Introduction. While a reduction in bone mineral density (BMD) is associated with aging, relatively few patients have formal dual-energy X-ray absorptiometry (DXA) to quantify the magnitude of bone loss, as they age. This loss of bone may predispose to fractures. Recent data, which correlates mean Hounsfield units (HU) in an area of the L1 vertebra with BMD, now makes it possible to screen for osteoporosis using incidental abdominal Computed Tomography (CT) scans to measure bone density. This innovation has the potential to reduce both cost and radiation exposure, and also make it easier to identify patients who may be at risk. The aims of this study were to evaluate the utility of this approach in patients with acute thoracic and lumbar spine fractures and to evaluate the impact of aging on BMD, using CT screening. Patients & Methods. Following institutional review board approval, we performed a retrospective study of patients who presented to a level I trauma center with acute fractures of the thoracic and lumbar spine between 2010 and 2013; patients also had to have had an abdominal (or L1) CT scan either during the admission or in the 6 months before or after their injury. Using a picture archiving and communication (PACS) system, we generated regions of interest (ROI) of similar size in the body of L1 (excluding the cortex) and computed mean values for HU. Values derived were compared against threshold values which differentiate between osteoporosis and osteopenia - for specificity of 90%, a threshold of 110 was set; for balanced sensitivity and specificity, a threshold of <135 HU was set and for 90% sensitivity a threshold of <160 HU was set. A student's t test was used to compare the age stratified mean HU (younger than 65yrs; 65yrs and older), while Fisher's exact test was used to perform aged stratified comparisons between the proportions of patients above and below the thresholds outlined (in each of the three threshold groups). Results. A total of 124 patients were evaluated, with 74 having thoracic and 50 having lumbar fractures. Among those with thoracic fractures, there were 33patients in the younger cohort, who also had a mean BMD of 196.51HU and 41 in the older cohort, who had mean BMD of 105.90HU (p<0.001). In patients with lumbar fractures, 27 patients were in the younger cohort, with mean BMD of 192.26HU and 23 patients in the older cohort with mean BMD of 114.31HU (p<0.001). At the threshold of 110 HU, set for specificity, the magnitude of difference between the age stratified cohorts was greater in the thoracic spine (p<0.001 vs. p=0.003). At the other thresholds: 135HU (balanced for sensitivity and specificity) and 160 HU (90% sensitivity), age of 65 years or older was significantly associated with reduction in CT derived measure of BMD (p<0.001 in all cases). Discussion. This study demonstrates the relative frequency of osteoporosis in acute fractures of the thoracic and lumbar spine, and how this changes with age; it is also the first study to do this using opportunistic CT scans. There seems to be a strong association between a reduction in bone mineral density and advanced age, in patients presenting with acute fractures of the spine. This approach may save on the extra cost and additional radiation exposure that may be associated with DXA scanning; in addition, it may help provide clinicians and patients with an approach to monitor developing problems with BMD before it becomes clinically apparent, especially in younger patients

In cases of severe postdysplastic coxarthosis, it seems to be impossible to recognize acetabular geometry and the real femoral position on a plain X-ray because the real diameters and angles can be disfigured when projected. Computed tomography (CT) provides important information to the surgeon about the concavity, shape and stereotomy of the acetabulum. It is quite difficult to correctly evaluate severely changed hips. CT displays more precise acetabular diameters and angles than a plain radiograph. Because of the high density of bony tissue, the CT makes it easy to produce a three-dimensional display of the hip. From September 1995 to December 1998, 224 patients (148 female, 76 male) underwent arthroplasty using a non-cemented prosthesis according to Zweymüller. A total of 236 hip joints were operated and classified as Crowe Group I (76 hips), Crowe Group II (149 hips), and Crowe Group III (11 hips). There were no Crowe Group IV hips. A total of 96 patients were examined by 3D CT in preoperative planning. Based on CT results, four joints were not recommended for an operative solution. CT protocol: scanner Elscint TWIN II, slice 2.5 mm, 120 kV, 285 mAs, matrix 3402,. No. of slices: 40–50, incremental dual acquisition. Postprocessing: axial images, multiplanar reconstructions, 3D SSD. Acetabular stereometry: superoinferior diameter, anteroposterior diam., depth, bottom thickness, femoral neck anteversion angle and subtrochanteric marrow diameter. A three-dimensional CT of the hip is a very effective tool for preoperative assessment

PURPOSE. Osteochondral talar defects (OCDs) are sometimes located so far posteriorly that they may not be accessible by anterior arthroscopy, even with the ankle joint in full plantar flexion, because the talar dome is covered by the tibial plafond. It was hypothesized that computed tomography (CT) of the ankle in full plantar flexion could be useful for preoperative planning. The dual purpose of this study was, firstly, to test whether CT of the ankle joint in full plantar flexion is a reliable tool for the preoperative planning of anterior ankle arthroscopy for OCDs, and, secondly, to determine the area of the talar dome that can be reached by anterior ankle arthroscopy. METHODS. In this prospective study, CT-scans with sagittal reconstructions were made of 46 consecutive patients with their affected ankle in full plantar flexion. In the first 20, the distance between the anterior border of the OCD and the anterior tibial plafond was measured both on the scans and during anterior ankle arthroscopy as the gold standard. Intra- and interobserver reliability of CT as well as agreement between CT and arthroscopy were assessed by intraclass correlation coefficients (ICCs) and a Bland and Altman graph. Next, the anterior and posterior borders of the talar dome as well as the anterior tibial plafond were marked on all 46 scans. Using a specially written computer routine, the anterior proportion of the talar dome not covered by the tibial plafond was calculated, both lateral and medial, indicating the accessible area. RESULTS. The distance between the anterior border of the OCD and the anterior tibial plafond ranged from −3.1 to 9.1 mm on CT and from −3.0 to 8.5 on arthroscopy. The intra- and interobserver reliability of the measurements made on CT-scans were excellent (ICC > 0.99, p < 0.001). Likewise, agreement between CT and arthroscopy was excellent (ICC=0.97; p < 0.001); only one patient showed a difference of more than 2.0 mm. The anterior 47.3 ± 6.8% (95%CI, 45.2–49.3) of the lateral talar dome, and 47.7 ± 7.0% (95%CI, 45.7–49.8) of the medial talar dome was not covered by the tibial plafond. CONCLUSIONS. Computed tomography of the ankle joint in full plantar flexion is an accurate preoperative planning method to determine the arthroscopic approach for treatment of OCDs of the talus. Almost half of the talar dome is directly accessible by anterior ankle arthroscopy

Introduction. A femoral rotational alignment is one of the essential factors, affecting the postoperative knee balance and patellofemoral tracking in total knee arthroplasty (TKA). To obtain an adequate alignment, the femoral component must be implanted parallel to the surgical epicondylar axis (SEA). We have developed “a superimposable Computed Tomography (CT) scan-based template”, in which the SEA is drawn on a distal femoral cross section of the CT image at the assumed bone resection level, to determine the precise SEA. Therefore, the objective of this study was to evaluate the accuracy of the rotational alignment of the femoral component positioned with the superimposed template in TKA. Patients and methods. Twenty-six consecutive TKA patients, including 4 females with bilateral TKAs were enrolled. To prepare a template, all knees received CT scans with a 2.5 mm slice thickness preoperatively. Serial three slices of the CT images, in which the medial epicondyle and/or lateral epicondyle were visible, were selected. Then, these images were merged into a single image onto which the SEA was drawn. Thereafter, another serial two CT images, which were taken at approximately 9 mm proximal from the femoral condyles, were also selected, and the earlier drawn SEA was traced onto each of these pictures. These pictures with the SEA were then printed out onto transparent sheets to be used as potential “templates” (Fig. 1-a). In the TKA, the distal femur was resected with the modified measured resection technique. Then, one template, whichever of the two potential templates, was closer to the actual shape, was selected and its SEA was duplicated onto the distal femoral surface (Fig. 1-b). Following that, the distal femur was resected parallel to this SEA. The rotational alignment of the femoral component was evaluated with CT scan postoperatively. For convention, an external rotation of the femoral component from the SEA was given a positive numerical value, and an internal rotation was given a negative numerical value. Results. The subjects were 4 knees in 4 males and 26 knees in 22 females. A mean age (for 30 knees) at the operation was 76.7 ± 6.1 years (range from 66.4 to 88.3). The posterior condylar angle was −0.27 ± 1.43, and the outlier, more than 3 degrees, was 1 case. Discussion. Conventionally, the SEA is palpated intraoperatively, however, the sulcus of the medial condyle sometimes cannot be identified precisely in osteoarthritic degeneration at the medial condyle. Also, the SEA is determined from the posterior condylar axis (PCA) by calculating the posterior condylar angle, which is between the SEA and the PCA, with the measurements from the preoperative CT scan. However, the residual cartilage thickness is not considered in this method, and thus, the SEA is possible to be inaccurate. The simple technology of our template allowed us to determine the SEA directly on the femoral surface, without any influence from bone degeneration. The femoral components could be implanted accurately, and therefore, the superimposed template was considered to improve TKA outcomes with the accurate SEA

Abstract

Summary Statement. It is now possible to diagnose osteoporosis using incidental CT scans; this approach has been used to objectively demonstrate the role of osteoporosis in fracture in ankylosing spondylitis patients. Background. In advanced disease, Ankylosing Spondylitis (AS) is frequently associated with a reduction in bone mineral density (BMD), this contributes to pain and predisposes to fractures. Quantifying this reduction in BMD is complicated by the simultaneous processes occurring, in which there is both an overgrowth of bone (syndesmophytes) and a concurrent loss of trabecular bone. Traditional methods such as dual-energy X-ray absorptiometry (DXA) struggle to generate accurate estimates for BMD in these patients. It has recently become possible to diagnose osteoporosis, with a high sensitivity and specificity, using incidental CT scans of the L1 vertebra. The purpose of this study was to evaluate the use of opportunistic CT screening in the diagnosis of osteoporosis in patients with AS who had sustained vertebral fractures. Patients & Methods. Following Institutional review board approval, patients with AS who presented, with acute fractures of the spine, to our facility between 2004 and 2013 were reviewed to assess whether or not they had a Computed Tomography (CT) scan of the abdomen on admission or in the 6 months before or after injury. In addition, patients were also required to have signs of advanced AS such as the presence of syndesmophytes and syndesmophyte bridging; patients with fractures through L1 were excluded. Of those fitting the criteria, a region of Interest (ROI) was generated over the body of L1, Hounsfield unit (HU) were then measured. Results. Of the 42 patients reviewed, a total of 17 AS patients fit the above criteria. 15 were male and 2 were female, mean age of the whole cohort was 69.9years (range 22–85; SD 15.9). Using a threshold balanced for sensitivity and specificity (<135 HU) which differentiates between osteopenia and osteporosis, 14 (82%) patients were found to have a BMD less than 135HU; a higher threshold (<160 HU) with 90 % sensitivity for differentiating osteoporosis from osteopenia was applied to the group, and 15 patients (88%) were found to be osteoporotic. Of note all the females in the study were osteoporotic. Discussion and Conclusion. This study demonstrates, for the first time, using opportunistic CT screening, that a high proportion of AS patients who sustain fractures have osteoporosis; this overcomes the difficulties that have been encountered with the use of DXA in this unique group of patients. This simple and accessible method saves on excess cost and exposure to radiation. With a high sensitivity, patients identified using this method can then be managed more proactively. We believe these data have the potential to significantly impact the day to day management of patients with spondyloarthropathies

Anterior lumbar inter-body fusion (ALIF) is a surgical procedure that is available to chronic lower back pain patients who fail to respond to conservative treatments. Failure to achieve fusion may result in persistence of pain. Fusion of the lumber vertebral segment is more accurately assessed using fine-cut helical Computed tomography (CT) scans (0.25 mm thickness slices). Unfortunately this technique exposes the body to high radiation dose with hazard of increase risk of late malignancy. An alternative imaging tool is radiostereometry (RSA) which developed as a means to determine the magnitude of relative motion between two rigid bodies. In this study we used RSA to detect movement at the fused lumbar segment (ALIF site) during flexion and extension and compare the results obtained with fine-cut helical CT scan using histopathology as final gold standard assessment tool. ALIF of three levels of lumbar spine (L1-L2, L3-L4, and L5-L6) was done in 9 sheep. The sheep divided into three groups (3sheep each). The first group had RSA assessment immediately, 3, and 6 months after surgery. The second group had RSA immediately, 3, 6, 9 months after surgery. The third group had an RSA immediately, 3, 6, 9, 12 months after surgery All the animals were humanly killed immediately after having the last scheduled RSA (group1, group2, and group 3 sheep were killed 6 month, 9month and 12 months after surgery respectively). This followed by in vitro fine cut CT and histopathology after the animals are scarified. Micro CT scan has been also used to identify the area where histopathology slide should be made to pick up fusion. Fine cut CT scan assessment for all sheep were done. The CT scan has been reported by two independent radiologists. Histopathology has been started and will finish in 2 weeks. RSA showed there was significant increasing stiffness of the spine though the fused segments as the time pass on compare to immediate postoperative assessment. CT scan were done and showed variable fusion though out the spinal segments. Histopathology of all sheep has been started and the results will be available in 2 weeks which will be followed by statistical assessment to decide how accurate RSA compare to CT scan in assessment of fusion

Aim: To determine the quantity and the quality of the bone bridge between the bone tunnels, in both the femoral and tibial side, after double-bundle anterior cruciate ligament (ACL) reconstruction. Material and methods: Twenty-seven patients undergoing primary double-bundle ACL reconstruction with hamstring tendon autograft were included in this prospective study. Computed tomography (CT) was performed in all patients at a mean of 13 months postoperatively. The amount of the bone bridge between the bone tunnels was measured, in both the femoral and tibial side, on an axial plane at three locations:. at the level of the joint line. at the mid-portion of the bone bridge and. at the base of the bone bridge. In addition, the bone density of the bone bridge was measured in Hounsfield units (HU) in the same locations. Bone density of the anterior tibial cortex lateral femoral condyle, and adjacent cancellous area, and were measured for comparisons. Results: CT confirmed that the bone bridge was triangular in shape in all cases in both the femoral and tibial side. On the femoral side, at the level of joint line (apex of the bone bridge) the mean thickness of the bone bridge was 1.7 mm, at the mid-portion the mean thickness of the bone bridge was 3.7 mm and at the base of the bone bridge the mean thickness was 7.1 mm. On the tibal side, at the level of joint line (apex of the bone bridge) the mean thickness of the bone bridge was 1.5 mm, at the mid-portion the mean thickness of the bone bridge was 3.2 mm and at the base of the bone bridge the mean thickness was 6.5 mm. Bone density at the mid-portion and at the base of the bone bridge was similar to the cancellous bone for both the femoral and tibial side. However, the bone density of the bone bridge, at the level of the joint line, for the femoral side was 860 HU and this was not statistically significant in comparison to the density of the lateral femoral cortex (960 HU). Similarly, the bone density of the bone bridge, at the level of the joint line, for the tibial side was 885 HU and this was not statistically significant in comparison to the density of the anterior tibial cortex (970 HU). Conclusions: Our study demonstrated one year after double-bundle ACL reconstruction the thickness of the triangular bone bridge between the bone tunnels is sufficient at the mid-portion and at the base of the triangle but is thin at the level of the joint line. However, the bone bridge at the apex of the triangle is very strong since its density is similar to that of cortical bone. We believe that the “corticalization” of the bone bridge at the level of the joint line on both the femoral and tibial side is important and contributes significantly to avoid communication of the bone tunnels

Introduction. Malrotation following total knee replacement is directly related to poor outcome. The knowledge of proximal and distal rotational axes and angles of the femur is therefore of high importance. The aim of the study was to determine whether the most used proximal and distal femoral angles; femoral anteversion angle (FAA) and posterior condylar angle (PCA) were different within individuals, between right, left and gender. As well, we studied whether the “inferior condylar angle” is correlated to the PCA and therefore useful in determining the rotation of the distal femur. Material and Methods. From 36 cadavers the femora were obtained and after removing the soft tissue a Computed Tomography (CT) scan was made. Three angles were measured: (i) the FAA between femoral columnar line (FHNL) and posterior condylar line (PCL), (ii) the PCA between anatomical transepicondylar line (TEL) and PCL, (iii) the inferior condylar angle (ICA) between the TEL and inferior condylar line (ICL). Statistical analysis of comparative relationships between the different angles was examined by calculating correlation coefficients and a paired t-test. Results. The mean FAA, PCA and ICA for the whole group were respectively 12.0 degrees (range 0.2–31.6, SD 8.3, 95% CI 9.6–14.4), 4.8 degrees (range 0.9–9.6, SD 2.3, 95% CI 4.1–5.4) and 4.5 degrees (range 0.1–9.8, SD 2.1, 95% CI 3.9–5.1). A strong correlation of the FAA was found within the total group and left versus right (r = 0.82; p = 0.00). A weaker relationship was found for the total group of the PCA measurements (r = 0.59; p = 0.00). When FAA compared to the PCA subdivided in only sexes, there is a weak correlation for the female group (r = 0.54; p = 0.00) Despite the small mean difference of the mean ICA and PCA, there was no correlation between these two angles. Conclusion. Considering the weak correlation of the FAA and PCA within the group but also individuals, the importance of development of more individual approaches for determining the optimal rotation of the components in total knee surgery is essential. As a result, one should be aware that the widely used, current guidelines for knee rotation of 3 degrees of external rotation in placing total knee arthroplasties shows variation between individuals. A more individual approach in total knee arthroplasty seems essential for future knee prosthesis implantations

Robotic-assisted technology in total knee arthroplasty (TKA) aims to increase implantation accuracy, with real-time data being used to estimate intraoperative component alignment. Postoperatively, Perth computed tomography (CT) protocol is a valid measurement technique in determining both femoral and tibial component alignments. The aim of this study was to evaluate the accuracy of intraoperative component alignment by robotic-assisted TKA through CT validation. A total of 33 patients underwent TKA using the MAKO robotic-assisted TKA system. Intraoperative measurements of both femoral and tibial component placements, as well as limb alignment as determined by the MAKO software were recorded. Independent postoperative Perth CT protocol was obtained (n.29) and compared with intraoperative values. Mean absolute difference between intraoperative and postoperative measurements for the femoral component were 1.17 degrees (1.10) in the coronal plane, 1.79 degrees (1.12) in the sagittal plane, and 1.90 degrees (1.88) in the transverse plane. Mean absolute difference between intraoperative and postoperative measurements for the tibial component were 1.03 degrees (0.76) in the coronal plane and 1.78 degrees (1.20) in the sagittal plane. Mean absolute difference of limb alignment was 1.29 degrees (1.25), with 93.10% of measurements within 3 degrees of postoperative CT measurements. Overall, intraoperatively measured component alignment as estimated by the MAKO robotic-assisted TKA system is comparable to CT-based measurements.

In total knee arthroplasty, polyethylene wear has been a major cause of revision surgery. However, it is sometimes difficult to determine the time of revision surgery in elderly people due to their concomitant diseases. Therefore, the brace for measuring polyethylene wear under computed tomography was developed.

Surgical navigation requires an accurate, stable transformation between the tracking system and reference images. This study was the design and evaluation of an additively manufactured calibrator with an integrated verification tool, used to register cone-beam computed tomography (CBCT) image volume to electromagnetic (EM) tracking.

An Aurora EM system was used to track both the calibrator and a surgical probe. Intraoperative CBCT images were acquired with a GE Innova 4100 scanner. The calibrator incorporated 7 tantalum beads, a 6DOF EM sensor, and 7 through-holes for calibrator verification. The calibrator was characterised using the beads and averaged EM reading in 10 poses.

Target Registration Error (TRE) estimation used a device with 14 beads and 18 through-holes. For verification, the probe was placed in each path and the axis and tip location measured relative to the calibrator. This verification task took about 45s. Axial error was the angle between the probed paths and designed axes; translation error was the shortest distance between these lines.

The translation TRE was 3.14±0.96 mm and the angular TRE was 1.7±0.7 degrees, which is consistent with published EM evaluations. The validation axes had an inter-line distance of 0.9±0.78 mm and an axial difference of 1.1±0.7 degrees. The verification errors were smaller than TRE because of the different mathematical formulation. Although the verification calculation was not exactly a tracking error, it provided an alternative quantitative assessment of registration accuracy. This integrated intra-operative registration verification minimises modifications to the surgical workflow and these results demonstrated highly accurate orientation tracking in a surgical environment.

Aim

To asses the accuracy of total knee replacements performed using CT based patient specific instrumentation by postoperative CT scan.

Introduction

The number of complex revision total hip arthroplasties (THA) is predicted to rise. The identification of acetabular bone defects prior to revision THA has important implications on technique and complexity of acetabular reconstruction. Paprosky et al. proposed a classification system including 3 main types with up to 3 subtypes focused on the integrity of the superior rim of the acetabulum and medial wall. However, the classification system is complex and its reliability has been questioned. The purpose of this study was to evaluate the effectiveness of different radiologic imaging modalities (plain radiographs, 2-D CT, 3-D CT reconstructions) in classifying acetabular defects in revision hip arthroplasty cases and their value of at different levels of orthopaedic training.

Introduction

Histology remains the gold standard in morphometric and pathological analyses of osteochondral tissues in human and experimental bone and joint disease. However, histological tissue processing is laborious, destructive and only provides a two-dimensional image in a single anatomical plane. Micro computed tomography (μCT) enables non-destructive three-dimensional visualization and morphometry of mineralized tissues and, with the aid of contrast agents, soft tissues. In this study, we evaluated phosphotungstic acid-enhanced (PTA) μCT to visualize joint pathology in spine osteoarthritis.

Osteophytes are bony spurs on normal bone that develop as an adaptive reparative process due to excessive stress at/near a joint. As osteophytes develop from normal bone, they are not always well depicted in common imaging techniques (e.g. CT, MRI). This creates a challenge for preoperative planning and image-guided surgical methods that are commonly incorporated in the clinical routine of orthopaedic surgery.

The study examined the accuracy of osteophyte detection in clinical CT and MRI scans of varying types of joints.

The investigation was performed on fresh-frozen ex-vivo human resected joints identified as having a high potential for presentation of osteophytes. The specimens underwent varying imaging protocols for CT scanning and clinical protocols for MRI. After dissection of the joint, the specimens were subjected to structured 3D light scanning to establish a reference model of the anatomy. Scans from the imaging protocols were segmented and their 3D models were co-registered to the light scanner models. The quality of the osteophyte images were evaluated by determining the Root Mean Square (RMS) error between the segmented osteophyte models and the light scan model.

The mean RMS errors for CT and MRI scanning were 1.169mm and 1.419mm, respectively. Comparing the different CT parameters, significance was achieved with scanning at 120kVp and 1.25mm slice thickness to depict osteophytes; significance was also apparent at a lower voltage (100kVp).

Preliminary results demonstrate that osteophyte detection may be dependent on the degree of calcification of the osteophyte. They also illustrate that while some imaging parameters were more favourable than others, a more accurate osteophyte depiction may result from the combination of both MRI and CT scanning.

Introduction: The successful outcome from metal-on-metal hip resurfacing is partly dependent on the restoration of the natural biomechanics of the hip joint. Valid measurement of the geometry of the reconstructed hip is challenging using plain radiographs. CT is more accurate and precise yet rarely used to assess hip geometry. Our aims were 1) to quantify the agreement between radiographic and CT measurement of horizontal femoral offset (HFO); 2) to determine the relationship between HFO and patient gender and size; and 3) To compare HFO of the reconstructed hip to the contralateral hip.

Method: We used plain radiograph and CT data from 42 patients (23 male and 19 female) from a consecutive series with unilateral metal-on-metal hip resurfacings. We measured HFO of both hips (component and contralateral) using plain radiographs (with PACS) and CT (with Robin 3D software). Pelvic width and radial head sizes were measured on CT. Measurements were made in triplicate by 2 observers.

We graded the contralateral hip for severity of joint space narrowing on plain radiographs.

Results: There was considerable disagreement between CT and plain radiographs for HFO. HFO was statistically different between genders (p=0.0004). HFO correlated with femoral head radius (0.57, p=0.0002), but not patient size (for height (0.29, p=0.13), or pelvic width (0.25, p=0.11). There was a wide range of HFO of the contralateral hips that was comparable to the reconstructed hip.

Conclusion: To our knowledge this is the first study to show the importance of measuring HFO using CT. HFO was found to be correlated to gender and femoral head radius, but not with any other parameters of patient size. The wide range of offset was considerably greater than is available from current total hip replacement designs. Hip resurfacing may overcome this.

Objective

In total hip arthroplasty (THA), the femoral component influences leg length inequality and gait, and is associated with poor muscle strength and other unsatisfactory long-term results. We have therefore used intraoperative radiographs to acquire accurate measurements of femoral component size and position. At the last meeting of this society, we reported that accurate positioning was successfully achieved in 68 cases (87.2%) as a consequence of taking intraoperative radiographs. However, we have little understanding as regards to the accuracy of X-ray measurements. We accordingly undertook an examination of the accuracy of such measurements. The purpose of this study was to evaluate the difference between leg length discrepancy (LLD) measured using X-ray and computed tomography (CT).

The authors are not aware of any research comparing computed tomography (CT) and avascular necrosis (AVN) of the scaphoid bone. The primary aim of our study was to investigate the use of longitudinal CT in predicting AVN of the proximal pole of the scaphoid, and subsequent fracture nonunion following internal fixation.

Thirty-two patients operated on by the senior author for scaphoid fracture were included. Preoperative CT scans were independently assessed for deformity, comminution, fracture position, proximal pole sclerosis, and bridging trabeculae. Intra-operative biopsy of the proximal pole was assessed independently by a blinded musculoskeletal histologist. AVN was determined by histology of a proximal pole biopsy, using the criteria described by Ficat. Post-operative CT scan was utilised to determine fracture union.

Preoperative CT features which significantly correlated with AVN were, increased radiodensity of the proximal pole, the absence of any bridging trabeculae comminution, dorsal cortical angle, proximal fracture and age less than 20. Features predictive of subsequent nonunion were fractures of the proximal, increased radiodensity of the proximal pole, and AVN.

Preoperative CT scan findings are significantly correlated with histologically confirmed AVN and fracture union. Preoperative longitudinal CT scan is of significant prognostic value and should be considered to assist in predicting outcome and assessing treatment options.

[Hong Kong Orthopaedic Association, Travelling Fellow]

Glenoid bone loss predisposes to further dislocation and failure of arthroscopic Bankart repair in patients with recurrent shoulder dislocation. This study investigates quantification of glenoid bone loss in anterior shoulder dislocation using computerized tomography (CT).

CT was performed in 40 patients (average age 31 years, range 16–82 years) with anterior shoulder dislocation. Of this group, 42 shoulders with anterior dislocation and 38 contralateral normal shoulders were examined. In addition, twenty shoulders in ten normal subjects were examined. CT technique comprised 1mm acquisition, pitch 1.0, simultaneously of both shoulders. Reformatted images en face to the glenoid fossa were obtained. Ten different measures of the glenoid fossa were obtained including cross sectional area, maximum height, and width and flattening of the anterior curvature of the glenoid.

In normal subjects, maximum side to side difference in cross-sectional area was 14% and maximum glenoid width 4.1mm. For dislocating shoulders, flattening of the anterior edge of the glenoid fossa and a reduction in maximum glenoid width were the best objective criteria of bone loss. Flattening of the anterior glenoid curvature was a feature of 95% dislocated shoulders though was only seen in 1.5% of normal shoulders. Glenoid cross-sectional area was not a useful measure of glenoid bone deficiency.

Variable glenoid bone loss is a measurable feature of anterior shoulder dislocation. CT can be used to objectively assess this preoperatively. This should help when deciding on whether to perform an arthroscopic Bankart repair or open bone block procedure.

Background

Humeral retroversion is variable among individuals, and there are several measurement methods. This study was conducted to compare the concordance and reliability between the standard method and 5 other measurement methods on Twodimensional (2D) computed tomography (CT) scans.

Introduction and Aims: There is a relationship between the anatomy of the hip joint and the development of arthritis. A common cause of hip pain in the young adult that can lead to arthritis is acetabular dysplasia. More recently, femoroacetabular impingement has been described as another cause of hip pain. The purpose of our study was to evaluate the applicability of pelvic computed tomography (CT) with three-dimensional surface rendering to evaluate femoro-acetabular impingement.

Method Thirty-six hips (30 patients; 17 males; 13 females) with persistent hip pain, mean age 41 (37–52), underwent three-dimensional CT of the pelvis, as well as MRI arthrography with gadolinium enhancement. On 3D CT, the concavity of the femoral head-neck junction (offset), alpha angle as described by Notzli was calculated to depict the anterior femoral neck contour. The concavity of the posterior aspect of the head neck junction was measured as the beta angle. The same measurements were made in 20 hips, consisting of randomly selected patients with no prior history of hip pathology or pain (mean age 37; 13 males; eight females).

Results The mean alpha angle for the symptomatic group was 66.4 (39–94) and 43.8 (39.3–48.3) for the control group (p=0.001). All symptomatic hips had abnormal findings on MRA: labral tears in all; cartilage delamination/ulceration in 14 hips; herniation pits in six hips. The majority of labral tears and delamination were located in the antero-superior quadrant. In the surgical treated group, all MRA findings were confirmed. The mean beta angle was significantly smaller (increase concavity) in the symptomatic versus the controls: 40.2 versus 43.8 (p=0.011). Interestingly in the symptomatic group the beta angle was significantly lower than the alpha angle (p< 0.02), but not in the controls.

Conclusion: 3D CT with surface rendering and multiplanar reformation is useful to determine degree of bone buttressing of the anterior femoral head-neck junction quantitatively assessed by alpha angle measurement, which is elevated in patients with femoro-acetabular impingement. With a greater posterior concavity i.e. small beta angle in the symptomatic group versus the control, subclinical slipped femoral epiphysis remains a plausible cause of this deformity.

Introduction and Aims: Little is known about peri-acetabular bone remodelling after insertion of the acetabular cup in total hip arthroplasty. This study was designed to analyse retroacetabular bone changes using quantitative CT-assisted osteodensitometry. This is a new method for a detailed measurement of bone density (BD) changes around the implants.

Method: Prospective cohort study. Operations were performed on 26 consecutive hips (26 patients) using an uncemented prosthesis with alumina-alumina pairing (Cerafit, Ceraver Osteal, France). The average age of patients was 58.4 years. There were 15 men and 11 women. CT investigations were performed within two weeks of surgery and then one year and three years post-operatively. Cancellous, cortical and total bone density (mgCaHA/ml) were assessed using specific software (Impact-Hip, VAMP, Moehrendorf, Germany).

Results: All 26 hips were available for follow-up at one year, seven patients were available at three years. At three-year follow-up we found an 18.4% decrease of cancellous BD proximal to the upper rim of the cup. Cortical BD increased by + 5.2% in this region. Cortical BD decreased ventral to the cup by −5.0% and by −2.3% dorsal to the cup. Of more interest, cancellous BD was observed to decrease by −40.9% in the ventral region and −32.2% in the dorsal region.

Conclusion: We have observed a progressive decrease of cancellous BD after insertion of an uncemented ace-tabular component. These phenomenon could explain the onset of late migration and implant failure of pressfit cups. Only minor changes have been observed in cortical BD. Further investigations are required to define the role of implant design and material in periprosthetic bone remodelling of the acetabulum.

Introduction

Fixation patterns of cementless stem were known as proximal or distal part. Distal fixation was seen in fully porous coated stem and stress shielding of the proximal femur was indicative. These phenomena did not lower the clinical results, but technical difficulties were more and more in revision surgery because of infection or dislocation. There was lot of reports that alendronate was effective for treatment of osteoporosis by induction of apoptosis in osteoclasts. We can expect alendronate to modify the bone quality around the stem after cementless THA.

Introduction

The treatment of trochanteric femoral fractures with the use of short femoral nails has become an established method. The fixation is required that lag screw be centered to prevent complications. But correct positioning of the device may difficult because of anatomical feature. This study evaluated the femoral morphology three-dimensionally using computed tomography (CT) images.

The orientation of the acetabular component in metal-on-metal hip resurfacing arthroplasty affects wear rate and hence failure. Correct assessment of acetabular orientation is key in assessing the painful hip resurfacing. This study aimed to establish if interpretation of pelvic radiographs with TraumaCad software can provide a reliable alternative to computed tomography (CT) in measuring the acetabular inclination and version.

TraumaCad was used to measure the acetabular orientation on AP pelvis radiographs of 14 painful hip resurfacings. Four orthopaedic surgeons performed each measurement twice. These were compared with measurements taken from CT reformats performed by an experienced musculoskeletal radiologist. The correlation between TraumaCad and CT was calculated, as was the intra- and inter-observer reliability of TraumaCad.

There is strong correlation between the two techniques for the measurement of inclination and version (p<0.001). Intra- and inter-observer reliability of TraumaCad measurements are good (p<0.001). Mean absolute error for measurement of inclination was 2.1°. TraumaCad underestimated version compared to CT in 93% of cases, by 12.6 degrees on average.

When assessing acetabular orientation in hip resurfacing, the orthopaedic surgeon may use TraumaCad in the knowledge that it correlates well with CT and has good intra- and inter-observer reliability but underestimates version by 12° on average. This underestimation may be contributed to by the natural divergence of the X-ray beam, the short arc of the ellipse left exposed by the large diameter head, and the non-hemispherical resurfacing cup.

Introduction: It has been proposed that rotational gait abnormalities in the normal child are usually reflections of the anatomic deformity. A decreased acetabular and femoral anteversion have been recognized as a predisposing factor for osteoarthritis of the hip and the McKibbin instability index was introduced to quantify this relationship. Additionally, an increased femoral anteversion has been associated with osteoarthritis of the knee. However, it is well known that compensatory factors influence the dynamic rotational profile during gait. We compared rotational computed tomography data with gait analysis to evaluate their correlation and to elucidate the influence of compensatory mechanisms.

Materials and Methods: In a prospective study conducted between 2001 and 2005 patients presenting with rotational malalignment were sent for 3D gait analysis. Main exclusion criterion was any kind of neurological affection. Patients in whom surgery was considered were referred to rotational computed tomography. The rotational alignment of the pelvis, hip and knee at different times during the gait cycle as evaluated in the 3D gait analysis was compared to the angular values derived from the rotational computed tomography for the femur and tibia and statistically analyzed and correlated.

Results: There were 12 female and 16 male patients with a mean age of 16 (± 9.7) years at the time of gait analysis. After a first evaluation of data 8 limb segments were excluded to increase the quality of data. The mean anteversion of the femur was 29 degrees (2 degrees of retrotorsion to 56 degrees of anteversion) and the mean tibial torsion was 31 degrees (1 to 66 degrees of external torsion). The calculation of the Pearson correlation showed that an increase of femoral anteversion resulted in an increase of pelvic range of motion. An increase of femoral anteversion resulted in an increase of the internal rotation of the hip. Highly significant correlations were found between the rotational–CT values for the tibia and the all parameters describing rotation of the knee. The determination coefficient was high for tibial torsion versus knee rotation (R2 = 0.64), but showed a low value for femoral anteversion versus hip rotation (R2 = 0.2).

Conclusion: The rotation of the hip as found in the gait analysis showed only weak correlation with rotational CT data. This is not surprising as the hips segment offers many possibilities for compensation. The torsion of the tibia was found to correlate very strongly with the gait analysis. The McKibbin index seems questionable as a prognostic factor for the individual patient in the light of a multitude of dynamic compensatory influences. Effort should be made to integrate the static instability index with dynamic gait analysis data.

Introduction: Concern remains in loosening of glenoid component reversed prostheses. This study is to analyze glenoid location of stem and 4 screws of glenoid component.

Material and method: 34 reversed prostheses included. Mean age 74,10, 33 females/1 male. Preoperative CT study : glenoid version; measure of anterior-posterior osteophytes. Postoperative CT study: central stem location and superior, inferior, anterior, posterior screws location. Study of influence of glenoid version and presence of osteophytes in location of glenoid implant.

Results: 27 retroverted glenoids (mean 6,5°); 7 ante-verted (mean 5,3°). 17 cases with anterior osteophyte and 12 of posterior. In 52% the central stem was centered inside glenoid, 33% anterior end was outside glenoid and 14% the posterior end. When central stem was anteriorly outside 85% presented retroverted glenoid (mean 8,33°). When the central stem was posteriorly outside 66% presented anteverted glenoid (mean 9,5°). Inferior screw was fully in place in 38%, ¾ part inside in 19%, 2/4 part in 23%, ¼ part in 19%. Superior screw was fully in place in 47%, ¾ part inside in 23%, 2/4 part in 19%, ¼ part in 9%. Anterior screw was fully in place in 66%, ¾ part in 23% and 2/4 part in 9%. Posterior screw was fully in place in 38%, ¾ part in 42%, 2/4 part in 14%, ¼ part in 4%. The correct positioning of superior screw correlates with less coverture of inferior screw. Anterior and posterior osteophytes did not correlated with stem nor screw positioning.

Conclusions: Positoning of central stem correlates with glenoid version. Anteriorly extruded stems correlate with higher retroverted glenoids and posteriorly extruded stems correlate with higher anteversion.

Positioning the inferior screw fully inside the lateral border of the scapula correlates with lower bony coverture of superior screw.

The purpose of this study was to evaluate in vivo fit and fill analysis of tapered wedge-type stem in total hip arthroplasty (THA) with computed tomography (CT)-based navigation system. 100 THAs were all performed through the posterolateral approach, with patients in the lateral decubitus position. Each cohort of 50 consecutive primary cementless THAs with was compared with and without CT-based navigation system. The post-operative antero-posterior (AP) hip radiographs were obtained two weeks after the operation. All radiographic fit and fill measurements in the proximal and distal areas were analyzed by two of the authors who were both blinded to the use of CT-based navigation system. The type of the fit in the cementless stem was divided into three types. The fit of the stem was classified as Type I, if there was both proximal and distal engagement (maximum proximal to distal engagement difference of 2 mm or greater), Type II when there was proximal engagement only, and Type III when there was distal engagement only. The fill parameters such as mean stem-to-canal ratios and mean minimum and maximum gaps between the stems to the cortical bone in proximal and distal sections were compared. There was a significantly better overall canal fit obtained by THA with CT-based navigation system compared to without the navigation system (p<0.01). With CT-based navigation system, 42 of 50 stems (84%) were categorized as Type I fit compared to 31 of 50 stems (62%) without the navigation system. As to Type II fit, There are significantly more stems without the navigation system (26%) compared to with it (12%). There were better canal fills of the stems obtained by THA with CT-based navigation system both in proximal (94%) and distal sections (88%) of the femur compared to without the navigation system (proximal 88%/distal 82%) (p<0.05). Excellent radiographic fit and fill has been previously reported to potentially correlate with improved clinical outcomes. The stems obtained by THA with CT-based navigation system had a significantly better canal fit demonstrated by higher proportion of Type I and lower proportion of Type II fits, compared to without the navigation system. The stems with the navigation system had also significantly better proximal and distal canal fill.

Introduction: Loss of the cervical lordosis is a common finding on the emergency department in patients who have been involved in a car accident as well as in those who have suffered head and neck injury. The difficult circumstances, under which the plain films are usually taken, make the use of CT indispensable. Our study presents the CT findings from the cervical spine in patients with loss of the cervical lordosis.

Method-Patients We studied 120 patients from February 2003 to January 2004. Their mean age was 37 years old. Our protocol included the lateral-AP view, while in the absence of findings, except loss of cervical lordosis, from the plain films, the patients underwent spiral CT within 24 h.

Results: Fractures of the cervical spine were found in 7 patients (5,8%). In 5 of them these involved the A1–A2 level. In two patients fractures of the occipital condyles were found. One A7 fracture coexisted with an A2 fracture. No patient had neurological symptoms.

Conclusions: The complete investigation of the cervical spine at the emergency department is often quite difficult. The possible underlying injuries can be potentially life threatening. The percentage of positive findings in our study is quite high to justify the routine use of spiral CT for the detailed investigation of such patients.

Aims

The primary aim of this study was to address the hypothesis that fracture morphology might be more important than posterior malleolar fragment size in rotational type posterior malleolar ankle fractures (PMAFs). The secondary aim was to identify clinically important predictors of outcome for each respective PMAF-type, to challenge the current dogma that surgical decision-making should be based on fragment size.

Articular cartilage has a limited regeneration capacity, and damage of cartilage often results in the onset of degenerative disease such as osteoarthritis (OA). MRI and CT imaging of cartilage and subchondral bone are becoming increasingly important in early detection and treatment of OA as well as for quantifying quality of tissue-engineered samples. Non-invasive CT scanners have been used to image cartilage tissue with the help of contrast agents. However, since only one energy source is available, imaging information of multiple soft and hard tissues is lost given that the overall x-ray attenuation is measured. Medipix All Resolution System (MARS) CT offers the possibility of applying more than one energy source. It is able to measure the energy of each photon individually and therefore determines the characteristics of attenuation.

In this study, an ionic contrast agent (Hexabrix) was used to image the negatively charged extra-cellular matrix component, glycosaminoglycan (GAG), which is abundantly found in the middle and lower layers of healthy cartilage tissue. GAG distribution in the cartilage tissue could be imaged using an inverse relationship with Hexabrix signal (i.e. high signal represents low GAG content). Eight bovine cartilage-bone explants (3mm × 5mm) were incubated in 4 different Hexabrix concentrations ranging from 20% to 50% in PBS. Sections were imaged using the MARS scanner at high and low energies (13.32 keV and 30.84 keV). Images were pre-processed, reconstructed and colour-coded using different enhancement techniques and virtual experimental software. Histological (Safranin-O) staining and quantitative biochemical analysis of GAG content (DMMB dye assay) was performed to correlate GAG distribution and content with MARS-CT images.

High resolution images of both cartilage and bone regions were obtained, with contrast enhanced CT of cartilage correlating well with histological staining. X-ray attenuation was high in regions poor in GAG content, whereas attenuation was low in GAG rich regions. Furthermore, there was a direct inverse correlation between Hexabrix signal and GAG content as measured in superficial (2.9 μg/mg) and middle/deep regions (10.6 μg/mg) in cartilage explants.

It can be concluded that the MARS technique can be used to image GAG distribution and GAG content, and therefore could be used clinically to assess quality of healthy or osteoarthritic cartilage, as well as non-destructive imaging of GAG content in engineered tissues.

Introduction: Compared with open instrumented anterior spinal fusion for adolescent idiopathic scoliosis (AIS), endoscopic surgery offers clinical benefits that include reduced pulmonary morbidity and improved cosmesis. However, quantitative data on the radiological improvement of vertebral rotation using this method is limited. The aim of this study was to measure pre-operative and postoperative axial vertebral rotational deformity at the curve apex in endoscopic anterior instrumented scoliosis surgery patients using computed tomography (CT), and assess the relevance of these findings to clinically measured chest wall rib hump deformity correction.

Methods: Between November 2002 and August 2005, twenty patients with right-sided thoracic curves underwent endoscopic single-rod anterior instrumented fusion. Pre and post surgical axial vertebral rotation was measured at the curve apex on preoperative and two-year postoperative CT using Aaro and Dahlborn’s method. Rib hump deformity correction was retrieved from a surgical database and correlated to the CT findings. Linear regression was used to investigate the correlation between apical vertebral rotation measured on CT and rib hump measured using a scoliometer.

Results: The mean angle of correction achieved in axial vertebral body derotation at the apical vertebra as measured by CT was 7.9°. This equated to a 43% improvement (range 20–90%). The preoperative and postoperative clinical measurements i.e. rib hump deformity correction, correlated significantly with CT measurements using regression analysis (p=0.03) and the mean improvement in rib hump deformity was 55%.

Conclusion: To our knowledge, this is the first quantitative CT study to confirm that endoscopic anterior instrumented fusion for AIS substantially improves the axial vertebral body rotational deformity at the apex of the curve. The margin of correction of 43% compares favourably historically published figures for all-hook-rod constructs in posterior spinal fusion. In addition, the CT measurements obtained significantly correlated to the clinical outcome of rib hump deformity correction.

Background: Complex fractures of the tibial plateau can be difficult to characterize on plain radiographs and two-dimensional computed tomography scans. We tested the hypothesis that three-dimensional computed tomography reconstructions improve the reliability of tibial plateau fracture characterization and classification.

Methods: Forty-five consecutive intra-articular fractures of the tibial plateau were evaluated by six independent observers for the presence of six fracture characteristics that are not specifically included in currently used classification schemes:

posteromedial shear fracture;

In addition, fractures were classified according to the AO/OTA Comprehensive Classification of Fractures, the Schatzker classification system and the Hohl and Moore system. Two rounds of evaluation were performed and then compared. First, a combination of plain radiographs and two-dimensional computed tomography scans (2D) were evaluated, and then, four weeks later, a combination of radiographs, two-dimensional computed tomography scans, and three-dimensional reconstructions of computed tomography scans (3D) were assessed.

Results: Interobserver agreement improved for all classification systems after the addition of three-dimensional reconstructions (AO/OTA κ2D = 0.536 versus κ3D = 0.545; Schatzker κ2D = 0.545 versus κ3D = 0.596; Hohl and Moore κ2D = 0.668 versus κ3D = 0.746).

Three-dimensional computed tomography reconstructions also improved the average intraobserver reliability for all fracture characteristics, from κ2D = 0.624 (substantial agreement) to κ3D = 0.687 (substantial agreement). The addition of three-dimensional images had limited infiuence on the average interobserver reliability for the recognition of specific fracture characteristics (κ2D = 0.488 versus κ3D = 0.485, both moderate agreement). Three-dimensional computed tomography images improved interobserver reliability for the recognition of coronal plane fractures from fair (κ2D = 0.398) to moderate (κ3D = 0.418) but this difference was not statistically significant.

Conclusions: Three-dimensional computed tomography is helpful for;

individual orthopaedic surgeons for preoperative planning (improves intraobserver reliability for the recognition of fracture characteristics), and for

Background: This study tested the null hypothesis that computed tomography (CT) and magnetic resonance imaging (MRI) have the same diagnostic performance characteristics for triage of suspected scaphoid fractures.

Methods: Thirty-four consecutive patients with a suspected scaphoid fracture (post-injury tenderness of the scaphoid and normal radiographs) underwent CT and MRI within ten days after trauma. CT-reconstructions were made in planes defined by the long axis of the scaphoid. The reference standard for a true fracture of the scaphoid was 6-week follow-up radiographs in four views, based on current literature. A panel including surgeons and radiologists came to a consensus diagnosis for each type of imaging considered in a randomized and blinded fashion, independent of the other types of imaging. We calculated sensitivity, specificity and accuracy as well as positive (PPV) and negative predictive values (NPV) for both imaging modalities.

Results: According to the reference standard there were six true fractures of the scaphoid (prevalence 18%). CT diagnosed fracture of the scaphoid in five patients (15%), with one false positive, two false negative and four true positive results. MRI diagnosed a fracture in seven patients (21%), with three false positive, two false negative and four true positive results. Sensitivity, specificity and accuracy for CT were 67%, 96% and 91%; and for MRI 67%, 89% and 85% respectively. According to the McNemar test for paired binary data for each imaging modality these differences were not significant. The positive predictive values using Bayes’ formula were 76% for CT and 54% for MRI. Negative predictive values were 94% for CT and 93% for MRI.

Conclusions: CT and MRI had comparable diagnostic characteristics. Both were subject to both false positive and false negative interpretations. They were better to rule out a fracture than to rule one in. The best reference standard for a true fracture is debatable

Apert’s syndrome (or acrocephalosyndactyly type 1) is a rare condition characterized by anomalies of the skull (craniosynostosis) in conjunction with complex syndactyly of the hands and feet. There are many studies involving the description and management of hand deformities in Apert’s syndrome. The study of foot anomalies however in children with Apert’s syndrome has been limited to individual case reports and small series. Plain radiographic studies have shown that during childhood, progressive fusion of the bones of the feet occurs. The management of these children’s feet has never been addressed in the literature.

Seven patients with Apert’s syndrome were included in our study. The study group consisted of 2 girls and 5 boys, age range 4–16 years. We performed plain radiography, 3-D computed tomography and paedobarographic studies on all seven children based on our observation that some children with Apert’s had prominent metatarsal heads with symptomatic callosities under the first and second metatarsal heads. Five of the seven children studied demonstrated a specific pattern both on paedobarographic studies and 3D computed tomography of an excessively plantar flexed, fused first and second rays.

A corrective extension osteotomy of the fused first and second rays were then carried out in one patient with an excellent post-operative result. We propose that by early recognition and correction of the pattern of an excessively plantar flexed first and second ray would improve both function and footwear.

Purpose of the study: Two principle angles describe the orientation of the acetabular reconstruction of hip arthroplsty: lateral inclination and anteversion. Lateal inclination is easily determined on the plain x-ray but the measurement of anteversion generally requires axial computed tomography (CT). The values measured for acetabular anteversion depend on the planes chosen as reference. Similarly the measurement of acetabular inclination using conventional radiographs is often considered imprecise due to the large number of variables involved. Several reference planes are described in the literature. The purpose of this work was to characterise the values obtained using two reference planes, the anterior pelvic plan (APP) used for navigation and the pelvic axis (proposed by other authors).

Materials and Methods: We used the Hip-Plane-Sympios^® software to determine lateral inclination and anteversions using each reference plane. The APP was defined by three points: the anterosuperior border of the pubic symphysis, the anterior border of the two antero-superior iliac spines. The pelvic axis was defined by three points: the centre of the S1 plateau and the centres of the two femoral heads. A control reference plane (the plane of the CT table which corresponds to the conventional radiographic plane) was also used. Seventy-six patients scheduled for total hip arthroplasty for osteoarthritis were included in this protocol.

Results: Values measured for the APP were: mean acetabular inclination 52.5°± 4.1° (40–62°), mean acetabular anteversion 24.1°±5.8° (14–35°). Values measured for the pelvic axis were: mean acetabular inclination 47.6°± 4.5° (37–59°), mean acetabular anteversion 12.9°±7° (2–31°). In the plane of the CT table: mean acetabular inclination was 50.6°±4.2° (38–57°) and mean acetabular anteversion 20.2°±702° (1–40°). All of these values were significantly different from the others (p< 0.001). Use of the APP yields values higher than conventional values and those obtained using the pelvic axis, yet the distributions remained identical.

Discussion: The APP is used for total hip arthroplasty navigation systems. It is important to recognised that the angles measured in reference to this plane are greater than the classical radiographic values measured for acetabular inclination. The pelvic plane produces angles closer to the generally accepted anatomic values. Angles measured relative to the radiographic table are intermediary.

Purpose: We report the operative technique and preliminary results for percutaneous osteosynthesis in the supine position with computed tomography guidance for acetabular fractures without joint displacement.

Material and methods: This prospective study conducted in a single unit included a consecutive non-randomised series of 55 patients who underwent surgery for an unstable pelvic injury between June 1996 and December 2000 under computed tomography guidance. In ten cases, the radiographic and computed tomographic analysis demonstrated a coronal fracture of one of the columns without joint displacement accessible for anteroposterior screw fixation. There were eight men and two women, mean age 35 years.

Surgery: the ten patients were operated on in the supine position, in the scanner room under the same aseptic conditions as in the operation room. The reference computed tomography slice was the Corse slice. The femoral vasculo-nervous bundle was identified. A threaded guide wire was inserted perpendicuallary to the fracture line, anteriorly to posteriorly (Cap Corse technique). A perforated screw with a 7.3 mm diameter was used to fix the fracture. Minimal post-surgical surveillance was 48 hours. Weight bearing was not authorised for six weeks to three months. Al patients were followed prospectively, and mean follow-up ws 16 months (12–36).

Results: Traction was lifted immediately after surgery in all cases. All the patients got up the day after surgery. Mean hospital stay was less than five days postoperatively in all cases. There were no complications (vascular, neurologic, infectious) and no secondary displacement. At last follow-up, he Postel Merle d’Aubigné score was 18 for eight patients, 16 for one and 14 for one. Two patients showed radiographic signs of degenerative hip disease.

Discussion: This percutaneous osteosynthesis method using computed tomographic guidance is reliable (100% well positioned screws) and avoids the need for traction in bed. Morbidity is low (no complications). Even though these eight patients did not present clinical and radiographic signs of osteoarthritis, this technique did not avoid the risk of degenerative hip disease in two patients.

Conclusion: An alternative to traction, percutaneous osteo-synthesis with computed tomographic guidance performed in the supine position for acetabular fractures is a cost-effective procedure.

Aims

To evaluate whether an ultra-low-dose CT protocol can diagnose selected limb fractures as well as conventional CT (C-CT).

Introduction: Open instrumented anterior spinal fusion for adolescent idiopathic scoliosis (AIS) is a proven technique for vertebral derotation that, compared with posterior spinal fusion procedures, invariably requires fewer distal fusion levels to be performed. With the advent and evolution of endoscopic anterior instrumentation, further clinical benefits are possible such as reduced pulmonary morbidity, improved cosmesis and less postoperative pain. However, quantitative data on the radiological improvement of vertebral rotation using this method is limited. The aim of this study was to measure preoperative and postoperative axial vertebral rotational deformity at the apex of the curve in endoscopic anterior instrumented scoliosis surgery patients using computed tomography (CT), and assess the relevance of these findings to clinically measured chest wall rib hump deformity correction.

Methods: Between November 2002 and August 2005, adolescent idiopathic scoliosis patients with right-sided thoracic major curves were selected for endoscopic single-rod anterior fusion by the senior authors. Low-dose pre-operative CT was performed as described previously (1) and two-year postoperative CT was also performed on consenting patients in accordance with local ethical committee approval. The pre and post surgical axial vertebral rotation was measured at the curve apex using Aaro and Dahlborn’s method (2). Intraobserver and interobserver variability was assessed. Additional clinical information such as rib hump deformity correction and change in the Cobb angle was retrieved from a surgical database and correlated to the CT findings. Least squares linear regression was used to investigate the correlation between apical vertebral rotation measured on CT and rib hump measured using a scoliometer.

Results: Twenty patients were included in the study. The mean angle of correction achieved in axial vertebral body derotation at the apical vertebra measured by CT was 7.9° (median preoperative angle 17.3° [range 12.5° to 27.3°] and median postoperative angle 10.3° [range 1.8° to 18.1°]. This equated to a 43% improvement (range 20–90%). The preoperative and postoperative clinical measurements i.e. rib hump deformity correction, correlated significantly with CT measurements using regression analysis (p=0.03) and the mean improvement in rib hump deformity was 55% (median preoperative 15.0° [range 10° to 30°] and median postoperative 7.0° [range 4° to 10°]). 95% confidence intervals for intraobserver and interobserver validity were within the ranges ±4.5° to ±6.4°.

Discussion: We believe this is the first quantitative CT study to confirm that endoscopic anterior instrumented fusion for AIS substantially improves the axial vertebral body rotational deformity at the apex of the curve. The margin of correction of 43% compares more favourably than the historically published figure of 24% in a cohort of patients with all-hook-rod constructs used for posterior spinal fusion (3). Patient age and gender demographics, curve magnitude and curve types in the historical study were similar to our group, and an identical CT protocol for measuring vertebral derotation was utilised. In addition, the CT measurements obtained significantly correlated to the clinical outcome of rib hump deformity correction.

Periprosthetic osteolysis is a serious medium to long-term complication of total hip arthroplasty. Interobserver reliability of detecting osteolysis around cementless ace-tabular components is reported to be poor using plain radiographs. Quantitative computed tomography (CT) provides sensitive and accurate measures of osteolytic lesion volume, however, there may remain a role for plain radiographs in monitoring progression of osteolysis. The aim of this study was to use quantitative CT to monitor the progression of osteolytic lesions around cementless acetabular components and to compare plain radiographs and CT in determining the progression of osteolysis.

A high-resolution multi-slice quantitative CT scanner with metal artefact suppression was used to determine the volume of osteolysis around 18 cementless acetabular components. The mean time since arthroplasty was 14 years (range 10–15 years) at the initial CT. Repeat scans of the hip were undertaken over a five-year period to determine progression of osteolysis with time. A second blinded observer examined anteroposterior and lateral plain radiographs taken at the same time as the CT scans and measured the location and area of osteolytic lesions.

CT measurements determined that in ten of 18 hips (56%), osteolytic lesions progressed by more than 1cm3/yr. Progression in size of osteolytic lesions was significantly associated with hips with larger osteolytic lesions at the initial CT (p=0.0005). The mean volume of osteolysis progression was 4.9cm3/year (range 2.8–7.5cm3/yr) for cases with osteolysis volumes greater than 10cm3 at the initial CT, and 0.7cm3/yr (range 0–2.3cm3/yr) for cases with osteolysis volumes smaller than or equal to 10cm3 at the initial CT (p=0.002). Importantly, the rate of osteolysis progression between CT scans varied greatly in some hips. In contrast, using plain radiograph assessment, progression in the area of osteolytic lesions was only detected in 10% of hips.

In conclusion, quantitative CT provides new insights into the natural history of periacetabular osteolysis. Total osteolysis volume greater than 10cm3 is associated with a high risk of progression and progress, on average, at a greater rate than those less than 10cm3. Plain radiographs, including a lateral view, are an unreliable clinical diagnostic tool to predict substantial progression of periacetabular osteolytic lesions.

Introduction: Symptomatic osteochondral lesions of the talus have been managed with a variety of operative techniques involving open or arthroscopic approaches to the ankle joint. The purpose of this study is to report our technique of drilling stable osteochondral lesions of the talus via a percutaneous retrograde approach using computed tomography for guidance.

Materials and Methods: Seven adult patients with Berndt and Harty Stage 2 or 2A/5 (subchondral cyst positive) talar osteochondral lesions, confirmed by magnetic resonance imaging, had retrograde drilling with CT guidance performed under local anaesthesia. Follow-up MR imaging was performed to investigate radiological evidence of healing.

Results: All retrograde drillings performed were technically successful.

Discussion: The concept of retrograde drilling is to preserve intact articular cartilage while encouraging revascularisation of the osteochondral fragment. The use of CT allowed drilling without conventional direct visualisation of the articular surface via arthrotomy or arthroscopy. The procedure can therefore potentially be performed in an outpatient setting. Suggestions are made from review of the literature as to improve further the technique for future studies.

We usually plan surgery for total hip arthroplasty (THA)using pre-operative X-ray templates. However, the technique provides only two dimensional (2D) images and therefore has limitations for planning three-dimensional (3D) objects. Recently it has become possible to describe 3D images using computer programs that use free down loaded computer software (Hip-op) that enable comparison between 3D templates obtained by computed tomography (CT) and 2D conventional X-ray templates.

Six hip joints in 6 patients (1 male, 5 females; age range at the time of operation, 49–77 years) were evaluated. Five of the patients suffered from secondary osteoarthritis of the hip (secondary OA), while the remaining patient suffered from osteonecrosis of the femoral head (ONFH). All the patients underwent THA using a cement less femoral stem (ANCA-FIT Wright Medical Technology, Arlington, Tennessee, USA). Pre-operative planning was performed using Hip-op software (Rizzoli Institute, Bologna, Italy). After the THA surgery, we carried out a repeat CT scan that was used to analyze stem fitting in the femur.

In all the patients it proved easy to obtain the pre-operative template. In 4 patients, the correct stem size was selected pre-operatively, while in the other 2 patients, the planned stem size was one size smaller than that actually implanted. In the 4 patients in whom the correct stem was selected, 2 had their template correctly assessed by conventional 2D images, 1 patient’s template was one size smaller than the implant, while the remaining patient’s template was two sizes smaller than the implant. In the 2 patients who received implants one size smaller than the CT template, 1 patient had the stem inserted in the virus position while in the other patient a fracture occurred during implantation

Preoperative planning for THA using a CT-based computer templating system proved to be a useful technique for the orthopedic surgeons.

Objective: Unicompartmental knee arthropasty (UKA) has recently attracted increased popularity and usage, though issues exist regarding tibial component failure. UKA instability may be due to insufficient bony support at the proximal tibia. Pre-operative knowledge of ‘safe’ resurfacing depths offering subchondral bony support could help minimize UKA instability. We recently developed a novel CT imaging tool (CTTOMASD) which assesses subchondral bone mineral density (BMD) in relation to depth from the subchondral surface. The objective of this work was to determine the in-vivo precision of CT-TOMASD safe resurfacing depths in human tibial compartments.

Seven knees from seven donors (2M:5F; age:46+/−11) were scanned three times via QCT (GE Lightspeed; BMD Phantom; 0.625x0.625x0.625mm resolution). CTTOMASD regional analyses were performed for medial and lateral compartments; outputting density versus depth plots fit with polynomial regression equations. As density decreases with increased depth from the subchondral surface, a density threshold of 300mg/ cm3 was arbitrarily set to correspond with the safe resurfacing depth. The 300mg/cm3 density threshold corresponds to the average density of subchondral trabecular bone, and is ~2x the density of weak epiphyseal trabecular bone located beneath stiffer subchondral trabecular bone. Precision was defined using coefficients of variation (CV%).

In-vivo precision errors associated with CT-TOMASD safe resurfacing depths were less than 2.7%. CV% was 2.7% for the medial compartment depth and 2.6% for the lateral compartment depth.

CT-TOMASD demonstrates repeatable measures of safe resurfacing depths invivo.

Safe resurfacing depths are measured in relation to defined density thresholds which can be adjusted according to UKA design and patient specifics (e.g., size, sex). CT induces a low radiation dosage due to the low presence of radiosensitive tissues at the knee (~1/10th of a long-leg standing radiograph). CT-TOMASD has potential to be used as a pre-operative imaging technique for improved UKA stability and longevity.

We evaluated the geometry of the resected femoral surface according to the theory for total knee arthroplasty (TKA) using three-dimensional computed tomography (3D CT).

The 3D CT scans were performed in 44 knees indicated as requiring total knee arthroplasty. The 3D images of the femurs were clipped according to the following procedures. The distal femur was cut perpendicular to the mechanical axis at 10 mm proximal from the medial condyle. Rotational alignment was fixed at 3 degrees external rotation from the posterior condylar line. The anterior condyle was resected using the anterior cortex as the reference point. The posterior condyle was cut at 10 mm anterior from the medial posterior condyle.

The medial-lateral (ML) width/anterior-posterior (AP) length was 1.58 ± 0.14 (mean ± SD). AP length of the 3D images tended to be longer than the box length of the three kinds of components provided when the ML width of the images was approximately equal to that of each component. The widths of medial and lateral posterior condyles of the images were 30.1 ± 3.8 mm and 24.8 ± 3.0 mm, respectively. In all except one case, the widths of the resected medial posterior condyles were greater than those of the medial condyles of all components when those of resected lateral posterior condyles were equal to those of the lateral condyles of the components.

The shapes of the resected femoral surface did not always match those of the components. The configuration of Japanese knee joints is different from that of American knee joints. Components with appropriate geometry should be designed for Japanese patients.

The scapulo-humerothoracic rhythm, which can be described by up to 12 spatial variables, is either responsible for, or affected by the genesis of shoulder pathology and trauma, and therefore, imaging the articulations of the shoulder through a global range of motion is desirable in aiding the diagnosis and management of both movement deficiency and osseous lesions.

4 control volunteers were seated between the toroid of the scanner and maximally slewn table on a customised tripod. The subjects were asked to carryout a sequence of defined movements, each over a period of 5 seconds. These included adduction to abduction in the scapular plane, internal rotation to external rotation at 0° and 90° abduction and flexion to extension. An EBCT C300 scanner was used with a multislice sequence imaging protocol to collect 8 transaxial slices per volume by sweeping an x-ray beam sequentially over 4 tungsten target rings and recording x-ray intensity via two fixed detector rings after the reflected beam passes through the body, enabling the acquisition of 20 volumes per movement with minimal radiation exposure. Each slice was post-processed by semi-automatic segmentation using Amira software, and reconstructed to produce three-dimensional reconstructions. Following this, a kinematic description of the joint complex was developed using SIMM, enabling quantification of up to 5 Degrees of Freedom at the Glenohumeral joint.

EBCT provides a quick and efficient method for direct real-time dynamic imaging of the shoulder girdle, although currently crude. As such, we hypothesis the ability of EBCT to image traumatic disruption to shoulder rhythm, and are currently pursuing this work. These reconstructions promise great potential for further clinical experience and quantitative analysis of small translations aided by achievable limited technological refinement of the modality.

Since acetabular osteolytic lesions following total hip arthroplasty (THA) may be asymptomatic until extensive bone loss occurs, early detection and monitoring the progression of these lesions is important. The purpose of this study was to use high resolution helical CT to determine the progression of the osteolytic lesions over time by comparing serial studies.

Fifty patients (Fifty-eight hips) with primary, cementless THA done between 1984–1996 were evaluated as part of an ongoing prospective study. These patients had a history of a high level of activity that was believed to place them at increased risk for accelerated polyethylene wear. The mean age was 51 yrs, 55% male:45% female. The average time from date of surgery to initial scan was 8.0 years (4.7–16.6). If an acetabular lytic lesion was identified, the patients were offered Alendronate for potential suppression of bone resorption with a repeat CT scan for follow-up. The area of the maximum size osteolytic lesions on axial images were measured on the initial scan and compared at the same level on the subsequent study.

The interval between scans averaged 15 months (10 – 27). Progression was noted on 87% hips. The mean initial area was 328 mm2 (40–1084) with the follow-up area of 386 mm2 (46–1344) with a mean of progression of 15.7%.

Once established, peri-acetabular lysis appears to be a slowly progressive, relentless process. Analysis of changes on serial CT, along with an assessment of the degree and location of lysis, provides an additional tool to evaluate the need for surgical intervention.

The purpose of this study was to investigate the bone anatomy in determining the rotational alignment in total knee arthroplasty (TKA) using CT scan. Axial CT images of eighty-four varus osteoarthritic knees undergoing TKA were analysed. On the images of the distal femur and the proximal tibia, base line for anterior-posterior axis of each component was drawn based on the epicondylar axis for the femur and medial one-third of the tibial tuberosity for the tibia. Angle between these two lines was analysed as the rotational mismatch between the components when they were determined based on the anatomical landmark of each bone. Thirty-eight knees (45%) showed more than 5-degree mismatch and seven knees (8.3%) showed the mismatch more than 10-degree. There was a tendency to put the tibial component in external rotation relative to the femoral component when they were aligned to medial one-third of the tibial tuberosity. The results have indicated that the landmark of each bone was the intrinsic cause of the rotational mismatch between the components. The surgeons performing TKA surgery should aware of this fact and should align the tibial component in a compromised position, if necessary, to have overall satisfactory clinical outcome.

INTRODUCTION: Malposition of the pelvis at the time of acetabular component insertion can contribute to malpositioning of the acetabular component. This study measures the variation in intraoperative positioning of the pelvis on the operating table during surgery by matching intraoperative radiographs with pre-operative computed tomograms (CT) using 2D-3D matching.

METHODS: This prospective study was comprised of a random sample of 45 patients (n = 45, 26 female, 19 male) who had received a total hip arthroplasty (THA) from a single surgeon from 10/21/2003 to 9/6/2007. No THA candidate was excluded for any reason, including body habitus (mean BMI = 27.7, range 17.5 – 42.3), underlying disease process, age (mean age at surgery = 57, range 27 – 80), sex or side of surgery (21 left THAs, 24 right THAs). According to our standard clinical treatment protocol, each patient had a pre-operative CT scan for CT-based surgical navigation of the hip arthroplasty and each patient had an intraoperative radiograph taken to assess component positioning. All THAs were performed in the lateral decubitus position on a radiolucent peg-board positioning device. Each patient’s intraoperative pelvic radiograph was taken after acetabular component and trial femoral component insertion with the leg placed in a neutral position on the operating table and with the xray plate aligned squarely with the operating table. The orientation of the pelvis on the operating table was calculated by comparing the intraoperative 2D projection to the 3D CT data-set using software that can perform 2D-3D matching (XAlign). This software has been validated previously. By matching the 3D CT dataset to the magnification and orientation of the plain radiograph, the position of the anterior pelvic plane relative to the operating table could be calculated.

RESULTS: The mean pelvic tilt (rotation around the medial-lateral axis) was 6.84 degrees of anterior pelvic tilt (lordosis) with a standard deviation of 7.95 degrees and a range from 27.24 degrees of lordosis to 4.96 degrees of kyphosis. The mean pelvic obliquity (rotation around the longitudinal axis) was 2.89 degrees anterior from neutral with a standard deviation of 9.44 degrees and a range from 29.36 anterior to 16.59 posterior from neutral. The mean pelvic rotation (rotation around the anterior-posterior axis) was 2.56 degrees cephelad, with a standard deviation of 4.10 degrees and a range from 10.88 degrees cephalad to 5.97 degrees caudad. Pearson correlation statistics showed no relation among pelvic position and body mass index or age. A correlation was seen between pelvic obliquity and pelvic rotation.

CONCLUSION: This study shows a high variability of intraoperative pelvic positioning in the clinical setting using accurate measurement tools. The greatest variation was seen in pelvic obliquity which has the greatest influence on anteversion/retroversion of the acetabular component. Additionally, pelvic obliquity and rotation appear related in our series. Since all of our intraoperative radiographs were taken with the leg in a neutral position, it is likely that the pelvis is even more greatly malpositioned at other times during the surgery when forces applied by retractors or upon the leg may be greater.

Previous studies have suggested that bone ongrowth occurs following revision hip arthroplasty to a tapered long stem distal fit modular prosthesis. This may affect outcome. We sought to quantify proximal bone ongrowth to one such prosthesis and correlate this with functional outcome.

A series of eight patients undergoing revision total hip arthroplasty with the a long taper, distal fit, grit blasted modular prosthesis (ZMR) had a CT performed within three months and then greater than one year following surgery. Changes in periprosthetic bone stock were measured. Functional scores at a minimum of five years were analysed.

Proximal bone ongrowth was generally poor and did not correlate with functional outcome score.

When more sensitive imaging is used to analyse bone ongrowth in this long stem distal fit prosthesis, proximal ongrowth is poor and not the key determinate of functional outcome.

In relation to the conduct of this study, no funding has been received from any source to support the costs of this study

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.

Introduction:

One of the complications occurring after total knee arthroplasty (TKA) is venous thromboembolism (VTE). The current screening techniques for VTE are venography, lower extremity vascular ultrasound, pulmonary scintigraphy, and contrast-enhanced computed tomography (CT). Although venography and lower extremity vascular ultrasound can detect deep venous thrombosis (DVT) in the lower extremities, pulmonary thrombosis poses a diagnostic problem. We performed contrast-enhanced CT screening for DVT and pulmonary embolism (PE) after TKA, and assessed the efficacy of the following prophylactics for VTE: fondaparinux, enoxaparin, and edoxaban.

Introduction: Malposition of the pelvis at the time of acetabular component insertion can contribute to malpositioning of the acetabular component. This study measures the variation in intraoperative positioning of the pelvis on the operating table during surgery by matching intraoperative radiographs with pre-operative computed tomograms (CT) using 2D-3D matching.

Methods: This prospective study was comprised of a random sample of 45 patients (n = 45, 26 female, 19 male) who had received a total hip arthroplasty (THA) from a single surgeon from 10/21/2003 to 9/6/2007. No THA candidate was excluded for any reason, including body habitus (mean BMI = 27.7, range 17.5 – 42.3), underlying disease process, age (mean age at surgery = 57, range 27 – 80), sex or side of surgery (21 left THAs, 24 right THAs). According to our standard clinical treatment protocol, each patient had a pre-operative CT scan for CT-based surgical navigation of the hip arthroplasty and each patient had an intraoperative radiograph taken to assess component positioning. All THAs were performed in the lateral decubitus position on a radiolucent peg-board positioning device. Each patient’s intraoperative pelvic radiograph was taken after acetabular component and trial femoral component insertion with the leg placed in a neutral position on the operating table and with the xray plate aligned squarely with the operating table. The orientation of the pelvis on the operating table was calculated by comparing the intraoperative 2D projection to the 3D CT dataset using software that can perform 2D-3D matching (XAlign). This software has been validated previously. By matching the 3D CT dataset to the magnification and orientation of the plain radiograph, the position of the anterior pelvic plane relative to the operating table could be calculated.

Results: The mean pelvic tilt (rotation around the medial-lateral axis) was 6.84 degrees of anterior pelvic tilt (lordosis) with a standard deviation of 7.95 degrees and a range from 27.24 degrees of lordosis to 4.96 degrees of kyphosis. The mean pelvic obliquity (rotation around the longitudinal axis) was 2.89 degrees anterior from neutral with a standard deviation of 9.44 degrees and a range from 29.36 anterior to 16.59 posterior from neutral. The mean pelvic rotation (rotation around the anterior-posterior axis) was 2.56 degrees cephelad, with a standard deviation of 4.10 degrees and a range from 10.88 degrees cephalad to 5.97 degrees caudad. Pearson correlation statistics showed no relation among pelvic position and body mass index or age. A correlation was seen between pelvic obliquity and pelvic rotation.

Conclusion: This study shows a high variability of intraoperative pelvic positioning in the clinical setting using accurate measurement tools. The greatest variation was seen in pelvic obliquity which has the greatest influence on anteversion/retroversion of the acetabular component. Additionally, pelvic obliquity and rotation appear related in our series. Since all of our intraoperative radiographs were taken with the leg in a neutral position, it is likely that the pelvis is even more greatly malpositioned at other times during the surgery when forces applied by retractors or upon the leg may be greater.

Introduction. Plain radiograph underestimates the lysis extent while bone defect determines acetabu-lar revision. We determine the multislice computed tomography (CT) efficacy with metal-artifact minimization to calculate the volume, extent and location of lytic lesions around a loose acetabular cup. Patients and Methods. 48 hips with a loose acetabular cup were evaluated before cup revision. Multislice CT scans with metal-artifact minimization (Toshiba-MEC CT) were done. Scans were taken at 135 kV and 250 mA to maximize the resolution and bone contrast. CT slice thickness was 3 mm and reconstruction index 1.5 mm. Evidence of osteolytic lesion on these scans was compared with plain radiographs and with intraoperative findings. Bone defects were classified according to Paprosky. Results. Acetabular lysis were found in the radiographs of 18 hips and in the CT scans of 36 hips. The most frequent locations of osteolysis were medial (32 hips) and posterior walls (23 hips). Radiographs underestimated the extent of the lysis: there were 28 hips with radiographic type 1 defects and 16 hips with CT defects; 6 and 11 with type 2; 8 and 10 with type 3A; and 6 and 11 with type 3B respectively (Wilcoxon test, p< 0.001). The mean volumetric bone loss was 35.4 cm3 . Intraoperative findings confirmed CT findings. Conclusions. Multislice CT scans with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis around the cup than are plain radiographs. Since CT scans allow us to show the extent and location of the osteolysis, they are useful to plan cup revision.

Introduction. Plain radiograph underestimates the lysis extent while bone defect determines acetabular revision. We determine the multislice computed tomography (CT) efficacy with metal-artifact minimization to calculate the volume, extent and location of lytic lesions around a loose acetabular cup.

Patients and Methods. 48 hips with a loose acetabular cup were evaluated before cup revision. Multislice CT scans with metal-artifact minimization (Toshiba-MEC CT) were done. Scans were taken at 135 kV and 250 mA to maximize the resolution and bone contrast. CT slice thickness was 3 mm and reconstruction index 1.5 mm. Evidence of osteolytic lesion on these scans was compared with plain radiographs and with intraoperative findings. Bone defects were classified according to Paprosky.

Results. Acetabular lysis were found in the radiographs of 18 hips and in the CT scans of 36 hips. The most frequent locations of osteolysis were medial (32 hips) and posterior walls (23 hips). Radiographs underestimated the extent of the lysis: there were 28 hips with radiographic type 1 defects and 16 hips with CT defects; 6 and 11 with type 2; 8 and 10 with type 3A; and 6 and 11 with type 3B respectively (Wilcoxon test, p< 0.001). The mean volumetric bone loss was 35.4 cm3 . Intraoperative findings confirmed CT findings.

Conclusions. Multislice CT scans with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis around the cup than are plain radiographs. Since CT scans allow us to show the extent and location of the osteolysis, they are useful to plan cup revision.

Introduction

Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination.

Introduction and Aims: CT is one of the most versatile and useful medical imaging modalities for computer assisted surgery (CAS) and monitoring bone remodelling. However, the high radiation dosage hinders its widespread use. We describe a method for generating smooth and accurate Finite Element (FE) meshes using CT data with reduced radiation exposure.

Method: We have performed serial CT assisted osteodensitometry measurement on seven patients who had a total hip replacement. FE models were generated automatically with cubic Hermite basis functions for both geometry and density. The meshes were fitted to the geometric and density data sets using least square’s fitting. Density was displayed over the surface of the elements using a colour spectrum. The effect of reducing radiation dosage was studied by generating five different types of FE meshes from each patient with different numbers of CT slices. The different mesh types were generated by varying the gap between slices.

Results: The mesh with the smallest number of CT slices used seven CT scans, with the gap between slices of 3cm on average while the mesh with the largest number of slices used 22 scans with the gap of 0.8cm. For the mesh with the largest number of CT slices, the average error after the geometric fitting was less than 0.5mm. The average error for the density fitting was 70.2 mg/ml. When expressed as the percentage to the overall density data range (0 ~ 1500 mg/ml), the average error was 4.7%. Meshes generated with a smaller number of CT slices had larger errors, and this increased as the number of slices used decreased. The error in geometry dropped dramatically (more than 50%) when more than 10 slices were used, whereas the error in density decreased approximately linearly as the number of slices increased. Overall, it was possible to generate realistic and smooth meshes with a geometrical error of less than 1.5mm and a density error less than 7% using 10 CT slices.

Conclusion: One strength of the current study is that we have used cubic Hermite elements, which requires much less information in generating FE meshes without sacrificing too much accuracy. Our study has shown that we can generate realistic and smooth meshes with about 10 CT slices of the proximal femur. This is important to enhance the power of CT in clinical applications.

Purpose: The position of the femoral implant in external rotation remains a controversial issue. It can be determined using bone landmarks (Whiteside line, parallel to the biepicondylar axis, 3° external rotation from the posterior condylar plane). For the last seven years, we have related femoral rotation to the orientation of the tibial cut in order to ensure good femorotibial stability in flexion using specific instruments (Cores®). This prospective study was conducted to examine the position of the femoral implant determined with this method and to measure the position from bone landmarks.

Material and methods: Twenty consecutive patients were included in this study. Bilateral computed tomographic measurements were made before and after surgery. Joining 8mm/8 slices were obtained for the femoral necks and 5mm/3 slices for the knees. The angle of femoral torsion was defined in two ways: the first by the angle formed between the axis of the femoral neck (on two superimposed slices) and the tangent to the most posterior part of the femoral condyles; the second by the angle formed between the epidondylar line and the posterior condylar line.

Results: The preoperative scans demonstrated that the angle between the biepicondylar line and the posterior condylar line was 5.8±1.5°. Using Cores®, led to an external rotation of the femoral implant to 2.7±0.6°. The postoperative scans demonstrated that the angle between the biepicondylar line and the posterior condylar prosthetic play was a mean 3.3°. The measurements using the femoral neck were less precise, with, in one case, an external rotation of 5°. The patella was well balanced postoperatively (irrespective of the external rotation position of the femoral implant).

Discussion: The angle of about 6° between the biepicondylar line and the posterior plane of the condyles has also been reported by others (Beaufils, Matsuda). To obtain a rectangular space in flexion, the posterior condyle cuts are more important medially than laterally. We found a correlation between the correction provided by the specific instrument set and the difference in the posterior condyle cuts, demonstrating the intraoperative precision of Cores®. It is difficult to orient the femoral piece parallel to the biepicondylar axis. This study demonstrates that there always remains 2 to 3° of inclination of the biepi-condylar axis from the posterior condylar plane.

Conclusion: The positioning the femoral implant parallel to the biepicondylar line leads to inducing an important external rotation. While using 3° rotation systematically would reduce the risk of internal malrotation, we feel it better to adapt the rotation to each individual knee depending on the anatomic presentation. Cores® enables positioning the femoral implant in external rotation as a function of the ligament balance obtained in flexion after peripheral tension is applied. This enables avoiding medial femorotibial laxity in flexion.

Primary internal fixation of uncomplicated scaphoid fractures is growing in popularity due to its advantages over conventional cast fixation. Performing the procedure percutaneously reduces the risk of infection and soft tissue damage, but can be tricky because of the small size and complex three-dimensional (3D) shape of this bone. Computer-assisted navigation has been an invaluable tool in other pin insertion procedures.

This in-vitro study aimed to evaluate two different rendering techniques for our navigation interface: (i) 3D volume rendering of the CBCT image to show digitally-reconstructed radiographs of the anatomy, and (ii) volume-slicing, analogous to CT-images.

As the shape of the scaphoid is highly variable, a plastic model of the wrist was constructed in order to provide consistency that would not be possible in a cadaver-based study. The plastic model featured a removable scaphoid such that a new one was replaced between trials. Three surgeons each performed eight trials using each of the two navigated techniques (yielding a total of 48 trials for analysis). Central placement of scaphoid fixation has been linked with mechanical stability and improved clinical outcomes, thus the surgical goal was to place a K-wire to maximise both depth from the surface and length of the drill path. The wire was drilled through the scaphoid, from distal to proximal, allowing for post-trial analysis of the drill path. A ceiling-mounted OptoTrak Certus camera (Northern Digital Inc., Canada) and a floor-mounted isocentric 3D CBCT C-arm (Innova 4100, GE Healthcare, France) permitted a registration transformation between the tracking and imaging systems to be computed preoperatively, before each trial, using a custom calibration device. Optical local coordinate reference bodies were attached to the wrist model and a custom drill guide for tracking with the Certus camera. During each trial, a 3D spin image of the wrist model was acquired, and rendered according to the technique under study.

For 3D volume rendering, the spin image was rendered as a digitally-reconstructed radiograph (DRR) that could be rotated in three dimensions. In the planning phase, the surgeon positioned a desired drill path on the images. Anterior-posterior and lateral views of the 3D volume rendering were used for navigation during the drilling phase. The real-time orientation of the drill guide was shown relative to these images and the plan on an overhead.

For volume-sliced (VS) navigation, the spin image was volume-rendered and sliced along the principal planes (axial, coronal, sagittal) for planning. A slider interface allowed the surgeon to scroll through the slices in each of the planes, as if they were looking at individual CT slices. Once the desired drill path was positioned, the volume-sliced views were reconfigured to show slices along the oblique planes of the planned path for navigation.

Following all trials, model scaphoids with wire intact were imaged using CT with a slice thickness of 0.625 mm. The CT series were segmented and used to construct 3D digital models of the wire and drilled scaphoid. Algorithms were developed to determine the minimum distance from the centerline of the wire and the scaphoid surface, and to compute the length of the drill path. Screw breach should be avoided as it disrupts the articular surface and may lead to a sequela of cartilage deterioration and osteoarthritic changes. The shortest distance measure was extrapolated to assess whether a standard fixation screw (Accutrak Mini, 1.78 mm radius) would have breached the scaphoid surface. There were three screw breaches noted in the 3D DRR trials, while only one occurred using volume-slicing. The minimum distance from the centerline of the wire to the scaphoid surface can also be thought of as a “safe zone” for screw breach. Although no difference in the mean distance (μ) was noted between groups (μ_DRR = 2.3 mm, μ_VS = 2.2 mm), the standard deviation (σ) was significantly higher for the DRR trials (σ_DRR = 0.50 mm, σ_VS = 0.37 mm, p < 0.1), suggesting a higher reliability of central placement using VS for navigation. In contrast, the length of the drill paths were significantly longer for the DRR trials (μ = 28.7 mm, σ = 0.66 mm) than for VS-navigation (μ = 28.3 mm, σ = 0.62 mm) at p < 0.1.

The surgical goal was to pick a path that maximised both the length of the path, as well as the minimum distance from the scaphoid surface. Algorithms were developed to find the paths that would maximise: (i) the length and (ii) the distance from the surface of the model scaphoid used in this study. The maximum possible length was 29.8mm (with a minimum distance of 2.2mm from the scaphoid surface), and the maximum distance was 3.3mm (with a length of 27.5mm). Therefore, the set of optimal drill paths had length > 27.5 mm, and distance > 2.8 mm. Of the DRR-navigated trials, 11 were below the minimum optimal depth, and only one trial was below the optimal length; 13 of the 24 trials (54%) were of both optimal length and depth. Of the VS-navigated trials, nine were below the minimal optimal distance, and four were below the minimum optimal length; 11 out of 24 trials (46%) were within both the optimal length and depth.

From this comparative study, we conclude that VS-navigation was superior in locating a central location for the fixation wire, while DRRs were superior in maximising the depth of the drill path. Thus, we propose a hybrid interface, incorporating both volume-slicing and DRRs, in order to maximise the effectiveness of navigation for percutaneous scaphoid pinning.

Purpose of the study: In accordance with the conclusions established at the SOFCOT symposium in 1988, we propose surgical treatment of displaced fractures of the calcaneus with screw fixation after reduction. We developed an original classification system of 3D computed tomography images which allows a precise description of the fractures and guides joint and calcaneal body reconstructions. The purpose of this work was to provide a precise analysis of operated fractures in order to identify prognostic factors and validate use of exclusive screw fixation for calcaneal fractures.

Materials and methods: This series included 60 operated articular fractures of the calcaneus. The Uthéza classification was: 12 vertical, 7 horizontal with 1 fracture line, 3 horizontal with 2 fracture lines, 23 mixed with 1 fracture line and 15 mixed with 2 fracture lines. 3D computed tomography evidenced the fundamental fracture lines and their anterior extension. Fixation was achieved with one screw inserted in a transverse position under the posterior facet and one oblique screw from the greater tuberosity to the sustentaculum tali.

The medial and lateral Böhler angles were measured on plain x-rays. The analysis included search for a double line on the posterior talocalcaneal facet, secondary body displacement, the position of the oblique screw and the degree of posttraumatic subtalar wear. The clinical criteria established in the 1988 SOFCOT guidelines were recorded. Analysis of variance, Pearson and Spearman coefficients, and RIDITS analysis (the most powerful method available for evidencing a relationship between two qualitative variables one of which is ordinal) were used to search for prognostic elements and correlations.

Results: No severe complications were encountered with the wide lateral access. A negative medial Böhler angle was significantly correlated with an additionnal posterior facet line. A mean 80 p. 100 reduction in the lowering of the medial part of the posterior facet and an 87 p. 100 reduction in lateral pivoting were achieved irrespective of the type of fracture. Minimal secondary body displacements were significantly related to anchorage of the oblique screw outside the sustentaculum tali. Functional outcome was satisfactory (very good + good + average) in 75 p. 100 of the cases and physical outcome in 50 p. 100 (very good + good) irrespective of the type of fracture. Outcome was significantly correlated with reduction in the Böhler angle, double lines on the posterior facet, secondary displacement and osteoarthritis.

Discussion: The 3D analysis of posterior facet fractures using our classification was useful in guiding reconstruction with correction of the medial lowering and the lateral pivoting. A negative medial Böhler angle was a factor of poor prognosis: more posterior facet lines, joint wear and deterioration of the functional and physical outcome. Good outcome required good reduction of the Böhler angle and good anchorage of the oblique screw in the sustentaculum tali. Good subtalar mobility was associated with pain relief. Uniform anatomic and pathologic classifications and precise analysis criteria are needed for pertinent comparison between series and proper definition for indications for first-line reconstruction-arthrodesis.

Conclusion: Measurement of the medial Böhler angle improves the sensitivity of revision criteria for articular fractures of the calcaneus. Screw fixation has proven its reliability.

Purpose: The position of the patella after implantation of a total knee arthroplasty is generally determined by static measurements on the femoropatellar 30° flexion view or on a computed tomography (CT) scan in full extension. We studied the kinetics of the patellar implant between 0° and 90° on dynamic CT scans to determine the influence of torsion of the femoral and tibial components on the patellar course.

Material and methods: Twenty patients with titanium total knee arthroplasties implanted in 1991 and 1992 underwent a dynamic CT study preoperatively and during the year following prosthesis implantation. An Imatron machine was used to obtain dynamic slices during knee flexion from 0° to 90°. The patient was installed in the prone position. Slice thickness was 8 mm for images centred on the lower end of the femur. Ten 50 ms images were obtained during flexion from 0° to 90°. The technique used preoperatively and postoperatively enabled study of transversal translation and tilt of the patella.

Results: The orientation of the patellar transversal bony axis remained closely parallel to the flexion axis of the knee (i.e. the epicondylar axis) both preoperatively and postoperatively, irrespective of the orientation of the femoral and tibial components. Between 0° and 90° flexion, the prosthetic patella exhibited a translation movement laterally to medially during the first degrees of flexion then medially to laterally during the last degrees of flexion. The transversal displacement of the patellar insert was less pronounced when the femoral component was placed in external rotation from the epicondylar axis. For femoral implants in internal rotation (mean 5°), the translation of the patellar insert was a mean 1.5 mm between extension and flexion. This translation was only a mean 1 cm for implants in external rotation (mean 5°). Contact between the patellar prosthetic component and the femoral prosthetic component were more harmonious when the femoral implant was placed in external rotation. Torsion of the tibial implant did not appear to have an impact on the transversal course of the patella in this series.

Discussion, conclusion: Rotation of the femoral component influenced the relationship between the patella and the femoral component in flexion-extension movements. However, torsion of the femoral component had little effect on the position of the patella itself. The patellar remained schematically parallel to the epicondylar axis, maintaining an orientation close to that observed preoperatively. The torsion of the femoral implant is the element that modifies its position under the patella and by consequence the relations between the patella and the femoral trochleae. These modifications are more pronounced when the knee is in extension than when the knee is in 90° flexion, excepting for the lift-off phenomenon observed at 90° flexion which is related to the trapezoidal femorotibial resection spaces.

Purpose of the study: Recent studies have demonstrated that navigation systems provide highly accurate cuts for orthogonal alignment of the lower limb. The accuracy has not to our knowledge been assessed for rotation. Rotation of the femoral piece, which results from a strategy independent of the bone cut, is designed to «correct» for epiphyseal torsion of the distal femur and thus obtain a biepicondylar axis parallel to the «surgical» posterior bicondylar line described by Berger (line drawn between the medial sulcus and the lateral epicondyle), i.e. forming un angle of 2° with the anatomic biepicondylar line described by Yoshioka (line from the medial to lateral condyles). The purpose of this study was to access the precision of navigation rotation.

Material and methods: This prospective consecutive study included 40 osteoarthritic knees undergoing total knee arthroplasty (TKA). The anatomic angle of distal femoral torsion (Yoshioka angle: angle formed by the posterior bicondylar line and the biepicondylar line) was measured on the pre- and post(3 months)-operative scans. Navigation (Navitrack, Zimmer) used the rotation given by the preoperative scan to guide the femoral cut with the objective of achieving a residual Yoshioka angle of 2°, i.e. parallel to Berger’s surgical biepicondylar line. The postoperative HKA measured on the pangonogram in the standing position was 179.6±2° with 85% of patients between −2° and +2°, confirming the reliability of the navigation system.

Results: The mean preoperative epiphyseal rotation of the distal femur was 6.4±1.8°. The mean postoperative measurement was 1.1±2.4°. Eighty percent of patients were within ±2° of the objective.

Discussion: We demonstrated in previous work that navigation-based rotation using intraoperative data is satisfactory as long as the degree of rotation is based on the preoperative scan (and thus takes into account the wide rang of distal femur torsion). Navigation-based rotation is a progress compared with standardized rotation. The few errors observed were related to insufficient identification of the posterior bicondylar line during navigation or to difficulties in interpreting the postoperative scan.

Aim: To evaluate the long term results of the combined treatment of hybrid external fixator and limited internal fixation along with the advantages using pre-operative and post-operative computed tomography scan in these cases.

Material and Methods: During a period of 12 months, 16 fractures of tibial plateau, were treated in 16 patients. Fractures were classified according to Schatzker’s staging system as type II 2 cases, type III 4 cases, type IV 3 cases, type V 4 cases, type VI 3 cases. Eleven patients were men and 5 women with a mean age of 42 years old (27–67 years). In all cases pre-operatively were programmed coronal and saggital reconstructed CT-Scan, revealed the precise location and degree of articular comminution and joint depression. The principles of ligamentotaxis was used to achieve the closed indirect reduction, and limited open reduction with internal fixation was performed in 9 patients. All cases were treated with hybrid external fixators. After the removal of the plants, CT-Scan was programmed for all the cases.

Results: All patients were evaluated with a mean period of follow up 1.9 years. Healing was achieved in all 16 cases with a mean period of 16 weeks. There was no non-union. Pin tract infection occurred in two cases. Two fractures developed a malunion (1 valgus deformity and 1 anterior angular deformity). Radiographic evidence of arthritis appeared in 2 patients during follow up. CT-Scan offer us the possibility to measure precious the sinking of the tibia plateau in degrees, the condylar widening in mm, the degeneration of joint space, the varus-valgus tilt in degrees, the articular step-off in mm and the bone healing. Based to post-operative CT-Scan information we can organize a safe rehabilitation program and aloud the full bear-weight in the perfect time.

Conclusions: The use of circular external fixators obtains good stabilization allows early joint motion, protects soft tissue envelope and in combination with minimal internal fixation on achieves satisfactory reduction. It is almost impossible to measure sinking of the tibia plateau since plain radiographs do not distinguish between a local defect and depression of the condyles. The pre-operative CT-Scan assists in the pre-operative management. The post-operative CT-Scan shows important information about bone healing. Postoperative radiographs may have led to an underestimation of the degree of residual displacement. On the contrary, CT-Scan demonstrates the exact grade of articular displacement and depending on CT-Scan results one can better manage the post-operative rehabilitation.

Study Aims: This study’s objectives were to measure pre-operative and postoperative axial vertebral rotational deformity at the curve apex in endoscopically-treated anterior-instrumented scoliosis patients using CT, and assess the relevance of these findings to clinically measured chest wall rib hump deformity correction.

Introduction: Thoracoscopic instrumented anterior spinal fusion for adolescent idiopathic scoliosis (AIS) has clinical benefits that include reduced pulmonary morbidity, postoperative pain, and improved cosmesis. However, quantitative data on radiological improvement of vertebral rotation using this method is lacking.

Methods: Between November 2002 and August 2005, 20 AIS patients with right-sided thoracic major curves underwent endoscopic single-rod anterior fusion. Preoperative and two-year postoperative CT was performed to assess axial vertebral rotation at the curve apex. Correlation between apical vertebral rotation measured on CT and rib hump measured using a scoliometer was assessed.

Results: The mean angle of correction achieved in axial vertebral body derotation at the apical vertebra measured by CT was 7.9° and equated to 43% improvement. Preoperative and postoperative rib hump deformity correction correlated significantly with CT measurements using regression analysis (p=0.03). The mean improvement in rib hump deformity was 55%. Conclusion: We believe this is the first quantitative CT study to confirm that endoscopic anterior instrumented fusion for AIS substantially improves axial vertebral body rotational deformity at the apex of the curve. The margin of correction of 43% compares favourably with historically published figures of 24% for patients with posterior all-hook-rod constructs. CT measurements correlated significantly to the clinical outcome of rib hump deformity correction.

Ethics: local committee approval

Statement of Interest: none

Pedicle screws allow for biomechanically secure fixation of the spine. However if they are misplaced they may effect the strength of the fixation, damage nerve roots or compromise the spinal cord. For these reasons image guidance systems have been developed to help with the accuracy of screw placement. The accuracy of pedicle screw placement outside the lumbar spine is not well published. To determine the accuracy of pedicle screw placement using CT scanning post operatively. Cortex perforations were graded in 2mm steps.

Prospective observational study. Plain x-rays are inaccurate for determining screw placement and therefore high definition CT scanning was used. The screw positioning on the post-operative CT scans was independently determined by a research registrar who was not present at the time of surgery. Screw position and clinical sequelae of any malposition.

Thirty patients (13 F:17 M) with segmental instability. Twelve were for metastatic disease, seven for trauma, seven for spondylolisthesis, three for atlanto-axial instability and one for a vertebral haemangioma. All patients were operated on by the senior author.

One hundred and seventy six pedicle screws were inserted in the thirty patients over the 20 month study period. Six screws violated the lateral cortex of the pedicle but none perforated the medial cortex. There were no adverse neurological sequelae.

The findings from this study will serve as a good comparison with future studies on pedicle screw placement, which may claim to improve accuracy and safety by the use of image guidance systems, electrical impedance or malleable endoscopes.

Purpose: Implantation of a prosthesis on a remodelled femur can cause technical difficulties affecting the outcome of the arthroplasty. We performed a tridimensional study of the femoral anatomy before prosthesis implantation for sequelar congenital hip dislocation.

Material and method: The series included 312 hips in 262 patients. The same radiography and computed tomography work-up was perfomred in all patients. There were 288 women and 84 men, men age 56 years. Mean weight was 66 kg and mean height was 163 cm. The crowe classification was 195 dysplasia, 123 dislocations (41% class I, 27% class II, 13% class III, 19% class IV). Telemetric measurements were: femoral isthma, the centre of the lesser trochanter, limb length discrepancy, the cephalo-cervico-diaphyseal angle. Computed tomographic measurements were: anterio-posterior and mediolateral dimensions and femur funneling, helitorsion between the bichondylar plane and the upper femur, anteroposterior diameter of the acetabulum.

Results: The mean mediolateral and anteroposterior diameters of the femoral canal at the isthma were 9.8 and 13.1 cm respectively in dysplasia and 9.3 and 12.6 cm, 9.4 and 12.7, and 9.7 and 13.6 cm in I, II, and III–IV congenital dislocations respectively. The femoral funneling index varied from 1.9 to 7.6 in dysplasia and from 2.6 to 7.9, 2.1 to 8.4 and 2.1 to 8.7 in I, II, and III–IV congenital dislocations respectively. The mean cephalo-cervico-diaphyseal angle was 129.3°, 131.9°, 136.8°, and 127.4° respectively. Maximal leg length discrepancy was 45, 57, 71, and 82 cm respectively. Mean helitorsion was 22.9° (1°–52°), 36.4° (8°–86°), 43.2° (2°–82°- and 38.4° (6°–68°) respectively. The mean anteroposterior diameter of the acetabulum was 52, 51.2, 53.1; and 49.6 cm respectively.

Discussion and conclusion: The dysplastic or dislocated femur is narrower than the normal femur with wide variations in funneling and cephalo-cervico-diphyseal angle. The mean difference in leg length increases gradually with helitorsion but with wide individual variability, irrespective of the grade. These tridimensional anatomic data can be useful for predicting difficulties in prosthetic treatment of these patients.

Introduction: While plain radiographs are the clinical standard for routine follow-up after total knee arthroplasty (TKA), periprosthetic osteolysis can be difficult to identify on radiographs because it is often obscured by the metallic prosthesis. This study sought to evaluate the pattern and size of periprosthtic osteolytic lesions after TKA in patients with rheumatoid arthritis using multi-detector computed tomography (MDCT).

Methods: We evaluated 25 primary cemented alumina-ceramic TKAs (LFA-I, Kyocera) using minimum 10-year CT scans. All TKAs had an alumina-ceramic femoral component, a titanium tibial baseplate with a poly-ethylene insert, and a polyethylene patella component, which had been fixed with cement. The average age at the time of surgery was 54.1 years. The average time interval between surgery and the computed tomography scan was 12.6 years. None of the patients in this study documented periprosthetic infection or had undergone bone grafting.

Results: The MDCT detected 31 lesions in 12 knees: 23 femoral and 8 tibial lesions.

All lesions occurred around the prosthetic rim, and the mean size of osteolysis per knee was 2.1 +/−1.5 cc (range, 0.4–4.7 cc). Only seven lesions in 6 knees were diagnosed as osteolysis on plain radiographs: 2 lesions at anterior femoral condyle and 5 lesions at tibial condyles. None of the lesions around the posterior condylar flanges detected on CT was identified on plain radiographs. None of the implants showed radiographic loosening or required reoperation.

Discussion: As the alumina-ceramic TKA allowed the CT scans to obtain clear images with little metal artifact, we could easily detect lesions and joint space communication. This study demonstrated that plain radiographs underestimated osteolysis, and that lesions around posterior femoral condyles were the most difficult to identify on radiographs. Although most of the lesions were small and may be of little clinical importance, this study confirmed that MDCT can accurately detect osteolysis and measure lesion volumes in alumina-ceramic TKA.

Aims

Although we often encounter patients with an aortic aneurysm who also have diffuse idiopathic skeletal hyperostosis (DISH), there are no reports to date of an association between these two conditions and the pathogenesis of DISH remains unknown. This study therefore evaluated the prevalence of DISH in patients with a thoracic aortic aneurysm (AA).

In recent years, some attempts have been made to develop a method that generates finite element (FE) models of the femur and pelvis using CT. However, due to the complex bone geometry, most of these methods require an excessive amount of CT radiation dosage. Here we describe a method for generating accurate patient-specific FE models of the total hip using a small number of CT scans in order to reduce radiation exposure.

A previously reported method for autogenerating patient-specific FE models of the femur was extended to include the pelvis. CT osteodensitometry was performed on 3 patients who had hip replacement surgery and patient-specific FE models of the total hip were generated. The pelvis was generated with a new technique that incorporated a mesh morphing method called ‘host mesh fitting’. It used an existing generic mesh and then morphed it to reflect the patient specific geometry. This can be used to morph the whole pelvis, but our patient dataset was limited to the acetabulum. An algorithm was developed that automated all the procedures involved in the fitting process.

Average error between the fitted mesh and patient specific data sets for the femur was less than 1mm. The error for the pelvis was about 2.5mm. This was when a total 18 CT scans with 10mm gap were used – 12 of the femur, and 6 of the pelvis. There was no element distortion and a smooth element surface was achieved.

Previously, we reported a new method for automatically generating a FE model of the femur with as few CT scans as possible. Here we describe a technique that customizes a generic pelvis mesh to patient-specific data sets. Thus we have developed a novel hybrid technique which can generate an accurate FE model of the total hip using significantly less CT scans.

An automated method of generating FE models for the total hip with reduced CT radiation exposure will be a valuable clinical tool for surgeons.

This study identified imaging parameter(s) which best predict the mechanical properties of distal tibia. Seventeen human cadaver tibiae were assessed by PQCT at four, eight and ten percent site from distal and tested in compression at the twenty-five percent distal portion. Ultimate compressive loads were recorded with a mean of 8276 ± 2915 N. Spearson rank correlation and stepwise regression analysis revealed that CoA, total BMC, SSI and SSI4-TrA4-CoD4 combination had statistically significant correlations with the failure loads. Among all imaging parameters, SSI had the highest relevance due to its account for geometry, density and material distribution, important factors for structural properties.

Musculoskeletal diseases, especially hip fractures, have huge and growing impact on Canadian society. To develop techniques for identification of high risk population, we needed a link between clinical evaluations and laboratory measures of bone health. This study identified imaging parameter(s) which best predict the mechanical properties of distal tibia.

Seventeen human cadaver tibiae were considered in this study (mean age seventy-four, SD six years). PQCT was used to assess the four, eight and ten percent site. It measured the cross-sectional area, bone mineral content and bone mineral density of the cortical bone, trabecular bone and combined. Strength Strain Index (SSI) was calculated from these measurements. Each tibia was cut at twenty-five percent distal. Compressive force was applied uniaxially through a custom-made PMMA indentor onto the distal plateau along the longitudinal axis of the tibia at a rate of 10mm/s. Load and displacement data were recorded. Spearson rank correlation and stepwise regression analysis were used to identify individual and combination of imaging variables that were related to ultimate failure load.

Ultimate failure loads were recorded with a mean of 8276 ± 2915 N. Cortical area (R_0.72), total BMC (R_0.72) and SSI (R_0.86) had statistically significant correlations with the failure load. Stepwise regression revealed that the combination of SSI, TrA, CoD at 4% site explained the greatest amount of variance (R2 = 0.868) and SSI was the major contributor. SSI takes the polar moment of inertia (geometry), density and distribution of material into account. This explains its relevance towards predicting the ultimate failure load.

Please contact author for referenced images

In recent years, some attempts have been made to develop a method that generates finite element (FE) models of the femur and pelvis using CT. However, due to the complex bone geometry, most of these methods require an excessive amount of CT radiation dosage. Here we describe a method for generating accurate patient-specific FE models of the total hip using a small number of CT scans in order to reduce radiation exposure.

A previously reported method for autogenerating patient-specific FE models of the femur was extended to include the pelvis. CT osteodensitometry was performed on 3 patients who had hip replacement surgery and patient-specific FE models of the total hip were generated. The pelvis was generated with a new technique that incorporated a mesh morphing method called ‘host mesh fitting’. It used an existing generic mesh and then morphed it to reflect the patient specific geometry. This can be used to morph the whole pelvis, but our patient dataset was limited to the acetabulum. An algorithm was developed that automated all the procedures involved in the fitting process.

Average error between the fitted mesh and patient specific data sets for the femur was less than 1mm. The error for the pelvis was about 2.5mm. This was when a total 18 CT scans with 10mm gap were used – 12 of the femur, and 6 of the pelvis. There was no element distortion and a smooth element surface was achieved.

Previously, we reported a new method for automatically generating a FE model of the femur with as few CT scans as possible. Here we describe a technique that customizes a generic pelvis mesh to patient-specific data sets. Thus we have developed a novel hybrid technique which can generate an accurate FE model of the total hip using significantly less CT scans.

Introduction: The purpose of this study was to evaluate the impact of volume rendering 3D computed tomography reconstructions on the inter- and intraobserver reliability of the OTA/AO and Neer classifications in the assessment of proximal humerus fractures.

Material and Methods: Four observers with different levels of clinical training classified forty proximal humerus fractures according to the OTA/AO and Neer classifications. Three rounds of evaluation were performed and compared. First, fractures were classified on the basis of plain radiographs alone. Then, four weeks later, the combination of plain radiographs and computed tomography scans with conventional 3D SSD reconstructions was evaluated. Finally, four weeks later, the combination of plain radiographs, computed tomography scans, and 3D volume rendering reconstructions was assessed. These readings were repeated in a newly randomized order after an interval of twelve weeks to evaluate intraobserver reliability.

Results: Interobserver reliability for the AO/ASIF classification showed good interobserver reliability with plain radiographs (k=0,65) and two-dimensional CT scans with conventional three-dimensional (SSD) reconstructions (k=0,71). Interobserver reliability improved to excellent when the fractures were classified on the basis of 3D volume rendering reconstructions scans (k=0,84).

Intraobserver reliability of the OTA/AO classification was good with plain radiographs (k=0,70) and improved to excellent after adding three-dimensional SSD reconstructions (k=0,80) and three-dimensional VR reconstructions (k=0,88).

Interobserver reliability of the Neer classification was poor with plain radiographs (k=0,39) and moderate with two-dimensional CT scans and conventional three-dimensional (SSD) reconstructions (k=0,56) and improved to good with the addition of 3D VR scans (k=0,74). Intraobserver reliability for was poor with plain radiographs (k=0,34), good with three-dimensional SSD reconstructions (k=0,61), and excellent with three-dimensional VR reconstructions (k=0,80).

Conclusion: In this study, three-dimensional volume rendering computed tomography improved the inter- and intraobserver reliability of the AO/OTA and the Neer classifications in the assessment of proximal humerus fractures. In the opinion of the authors, 3D volume rendering CT-scans are a helpful tool for preoperative planning and classification of fractures of the proximal humerus.

Purpose: To determine if multidetector-row CT (MDCT) can replace conventional radiographs and be performed alone in severe trauma patients for the depiction of thoracolumbar spine fractures. Materials and Methods: One hundred consecutive severe trauma patients who underwent conventional radiographs of the thoracolumbar spine as well as thoraco-abdominal MDCT were prospectively identiþed. Conventional radiographs were reviewed independently by 3 radiologists and 2 orthopedic surgeons, and MDCT by 3 radiologists. Reviewers were blinded both to each other and to the results of the initial evaluation of these examinations. Presence, location and stability of fractures, as well as quality of reviewed imaging methods were assessed. Statistical analysis was performed to determine sensitivity and inter-observer agreement of each procedure, with clinical and radiological follow-up chosen as the reference standard. Time to perform each examination as well as involved radiation doses were also evaluated. Finally, a resource cost analysis was performed. Results: Sixty-seven fractured vertebrae in 26 of the patients were diagnosed. Twelve patients showed unstable spine fractures. Sensitivity and inter-observer agreement for unstable fractures amounted to 97.2% and 95.1% with MDCT, and 33.3% and 36.8% with conventional radiology. Average times in the performance of conventional radiographs and MDCT examinations amounted to 33 minutes and 40 minutes, respectively. Effective radiation doses involved in conventional radiographs of the spine and thoraco-abdominal MDCT amounted to 6.36 mSv and 19.42 mSv, respectively. MDCT afforded identiþcation of 145 associated traumatic lesions. Finally, costs of conventional radiographs and of MDCT amounted to 145 US$ and 880 US$ per patient, respectively. Conclusion: MDCT is a better test for depicting spine fractures than conventional radiographs. It can replace conventional radiographs and be performed alone in severe trauma patients.

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.

Aims

Femoroacetabular impingement (FAI) has been highlighted and well documented primarily in Western countries and there are few large studies focused on FAI-related morphological assessment in Asian patients. We chose to investigate this subject.

Aims

Patient-specific glenoid guides (PSGs) claim an improvement in accuracy and reproducibility of the positioning of components in total shoulder arthroplasty (TSA). The results have not yet been confirmed in a prospective clinical trial. Our aim was to assess whether the use of PSGs in patients with osteoarthritis of the shoulder would allow accurate and reliable implantation of the glenoid component.

We investigated the blood flow to the femoral head during and after Resurfacing Arthroplasty of the hip.

In a previous study, we recorded the intra-operative blood flow in 12 patients who had a posterior approach to the hip and 12 who had a trochanteric flip approach. Using a LASER Doppler flowmeter, we found a 40% drop in blood flow in the posterior group and an 11% drop in the trochanteric flip group (p<0.001). The aim of this current study was to find out whether the intra-operative fall in blood flow persists during the post-operative period.

We therefore conducted a Single Positron Emission Tomography (SPECT) scan on 14 of the same group of patients. The proximal femur was divided into four regions of interest. These were the mid-shaft, proximal shaft, inter-trochanteric and head-neck regions. The data was analysed for bone activity and comparisons made between the two groups for each region of the femur. We found that the bone activity in the mid-shaft, upper-shaft, and head-neck regions was the same eleven months after the surgery irrespective of the approach to the hip. However there was higher activity in the trochanteric flip group in the inter-trochanteric region.

We conclude that the intra-operative deficit in blood flow to the head-neck region of the hip associated with the posterior approach does not seem to persist in the late post-operative period. We believe the reason for increased bone activity in inter-trochanteric region to be due to the healing of the trochanteric flip osteotomy.

Purpose: The purpose of this work was to compare the precision and reliability of screw fixation using two different guiding systems. The first system was based on computed tomography (CT) imaging and the second on digitalized fluoroscopic imaging.

Material and methods: Between 1998 and 2000, 88 patients underwent spinal fixation for diverse disease states (idiopathic scoliosis in 43, and fracture, spondylolisthesis or instability in 45). Pedicular screws (n = 223) were inserted in levels T4 to S1. The passive CT navigation system was used for 73 patients (177 pedicular screws) and the fluoroscopic navigation system for 15 (46 pedicular screws). An independent observer identified the position of the pedicular screws on the postoperative CT.

Results: Among the 73 patients who underwent a CT-guided procedure (177 pedicular screws) the rate of incorrect screw position was 6.2% (11/117) with = 2 mm penetration of the cortical. Among the 15 patients who underwent a fluoroscopy-guided procedure (46 pedicular screws), the rate of incorrect screw position was 17% (8/46) again with = 2 mm penetration of the cortical. For scoliosis patients, the rate of erroneous screw insertion was 6% for CT navigation and 28% for fluoroscopic navigation. For fractures and degenerative instability, the rates were 6% and 11% respectively.

Discussion: The passive nature of the two navigation systems used do not induce any peroperative constraint on the surgeon. With the CT system, landmarks have to be collected peroperatively on the posterior arch of the operated vertebra, a step that is not needed for the fluoroscopic system. The two techniques appear to be reliable for insertion of pedicular screws. We did not have any neurological disorders in this series. It can be recalled that the conventional method produces a 15 to 40% rate of erroneous insertion. The CT system provides better results for all types of diseases; the improvement is about 6%.

Conclusion: With CT-navigation, a large portion of the per-operative radiographs are no longer necessary. Operative time is slightly longer than for the classical procedure due to the collection of the 3D information, particularly important for scoliosis. With the fluoroscopy system, no special preoperative imaging is required. Two or three peroperative radiographs are sufficient, limiting irradiation during insertion of the pedicular screws. The fluoroscopic system does not however provide 3D images.

Purpose: Bone mineral density (BMD) is an important factor in the performance of orthopaedic instrumentation both in and ex-vivo, and until now, there has not existed a reliable technique for determining BMD at the precise location of such hardware. This paper describes such a technique using cadaveric human sacra as a model.

Method: Nine fresh-frozen sacra had solid and hollow titanium screw placed into the S1 pedicles from a posterior approach. High-resolution micro-computed tomography (CT) was performed on each specimen before and after screw placement. All images were reconstructed with an isotropic spatial resolution of 0.308 mm, reoriented, and the pre-screw and post-screw scans were registered and transformed using a six-degree rigid-body transformation matrix. Once registered, two points, corresponding to the center of the screw at the cortex and at the screw tip, were determined in each scan. These points were used to generate cylindrical regions of interest (ROI) with the same trajectory and dimensions as the screw. BMD measurements were obtained within each of the ROI in the pre-screw scan. To examine the effect of artefact on BMD measurements around the titanium screws, annular ROI of 1 mm thickness were created expanding from the surface of the screws, and BMD was measured within each in both the pre-and post-screw scans.

Results: The registration process was accurate, with an error of 0.2 mm. Four specimens were scanned five times with repositioning, and error in BMD measurements was ± 2%. BMD values in the cylindrical ROI corresponding to screw trajectories were not statistically different from side to side of each specimen (p = 0.23). Artefact-related differences in BMD values followed an exponential decay curve as distance from the screws increased, approaching a low value of approximately 20 mg HA/cc, but not disappearing completely.

Conclusion: CT in the presence of metal creates artefact, making measured BMD values near implants unreliable. This technique is accurate for determination of BMD, non-destructive, and eliminates the problem of this metal artefact through the use of co-registration of a pre- and post-screw scan. This technique has applications both in-vitro and in-vivo.

Introduction: Low-intensity pulsed ultrasound stimulation (LIPUS) can enhance bone regeneration and callus healing during fracture repair. However, whether a certain phase of the healing process in fracture repair in particular is infiuenced by LIPUS treatment remains unclear. In this investigation, the effect of LIPUS on callus remodeling in a gap healing model was evaluated by bone morphometric analyses using 3-dimensional (3D) quantitative micro computed tomography (μCT) at the healing site, providing information on the temporal sequence of mineralized remodeling events that characterize the gap healing.

Materials and Methods: The rabbit osteotomy model with 2-mm gap for the right tibia was immobilized with four pins fixed to an external fixator with double side bars. LIPUS was continued for both the treatment group (n=7/group/time point) and the control group (n=7/group/time point), for 20 min, six times/week, for 4, 6, or 8 weeks. The control group also received a sham inactive transducer under exactly the same condition as the LIPUS group. After the harvested tibia was scanned by μCT, region of interest was set at the callus healing area. It defined as a center of the osteotomy gap with a width of 1 mm. Morphometric parameters used for evaluation were mineralized callus volume (BV, cm³) and volumetric bone mineral density of mineralized tissue comprising the callus (mBMD, mBMD = BMC/ BV, mgHA/cm³). The whole ROI was measured and was subdivided into three zones. The periosteal callus zone (External), the medullary callus zone (Endosteal) and the remaining zone was the cortical gap zone (Intercortical). For each zone, BV and mBMD were measured. Data of the μCT evaluations were analyzed using a one-way ANOVA test. Statistically significant difference was set at p < 0.05.

Results: In the LIPUS groups, BV for the Endosteal zone was significantly lower for the 8-week group than for the 4-week group. Comparing results at the same time point, the LIPUS group at 8 weeks was significantly higher than that of the control group in the Intercortical zone. As for mBMD, in the LIPUS group, the 8-week group was significantly higher than the 4-week group for Total, External, Internal, and Endosteal zones, respectively. Comparing results at the same time point, mBMD was significantly higher for the LIPUS group at 8 weeks than for the control group in both External and Intercortical zones.

Discussion: The most striking finding in our study was that LIPUS accelerated bone formation in the Intercortical zone and callus resorption in the Endosteal zone. This suggests that LIPUS could shorten the time required for remodeling. However, the results of this study do not clarify whether an early phase in callus formation in particular is infiuenced by LIPUS.

Objectives

The clinical utility of routine cross sectional imaging of the abdomen and pelvis in the screening and surveillance of patients with primary soft-tissue sarcoma of the extremities for metastatic disease is controversial, based on its questionable yield paired with concerns regarding the risks of radiation exposure, cost, and morbidity resulting from false positive findings.

Objective

The objective of this study was to evaluate the rotation and translation of each joint in the hindfoot and compare the load response in healthy feet with that in stage II posterior tibial tendon dysfunction (PTTD) flatfoot by analysing the reconstructive three-dimensional (3D) computed tomography (CT) image data during simulated weight-bearing.

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.

Objectives

This study aims to assess the correlation of CT-based structural rigidity analysis with mechanically determined axial rigidity in normal and metabolically diseased rat bone.

The aim of this study was to investigate the effect of different loading scenarios and foot positions on the configuration of the distal tibiofibular joint (DTFJ). Fourteen paired human cadaveric lower legs were mounted in a loading frame. Computed tomography scans were obtained in unloaded state (75 N) and single-leg loaded stand (700 N) of each specimen in five foot positions: neutral, 15° external rotation, 15° internal rotation, 20° dorsiflexion, and 20° plantarflexion. An automated three-dimensional measurement protocol was used to assess clear space (diastasis), translational angle (rotation), and vertical offset (fibular shortening) in each foot position and loading condition. Foot positions had a significant effect on the configuration of DTFJ. Largest effects were related to clear space increase by 0.46 mm (SD 0.21 mm) in loaded dorsal flexion and translation angle of 2.36° (SD 1.03°) in loaded external rotation, both versus loaded neutral position. Loading had no effect on clear space and vertical offset in any position. Translation angle was significantly influenced under loading by −0.81° (SD 0.69°) in internal rotation only. Foot positioning noticeably influences the measurement when evaluating the configuration of DTFJ. The influence of the weightbearing seems to have no relevant effect on native ankles in neutral position

Objective. The purpose of this study was to determine the outcomes of revision ankle replacements, using the Invision implant and impaction allograft for massive talar dome defects following primary ankle replacement failure. Outcomes were assessed in terms of bone graft incorporation; improvement in patient reported outcome measures (PROMs); and survivorship of the revision ankle arthroplasty. Methods. A retrospective review of prospectively collected data identified eleven patients who had massive bone cysts and underwent revision of a failed primary total ankle replacement to the Invision revision system, combined with impaction grafting using morselized femoral head allograft. These revisions occurred at a single high volume ankle arthroplasty centre. Computed tomography (CT) scans were used to assess bone graft incorporation and the Manchester-Oxford Foot Questionnaire (MOXFQ) and EQ-5D scores were used pre and post operatively to assess PROMs. Results. The mean follow up was 18 months (12–48months). In all eleven patients, improvement was reported in the post-operative MOXFQ and EQ-5D scores. CT scans showed bone graft incorporation in all cases. None of the patients have required further surgery and are continue to do well clinically at latest follow up. Conclusions. In the short term, this study confirms revision ankle replacements with the Invision prosthesis and impaction with morselized femoral head allograft is a suitable revision option for primary ankle replacement failure with massive talar bone loss. Long term follow up continues of these complex patients

Orthopaedic injuries in the knee are often associated with vascular injury. When these vascular injuries are missed devastating there are devastating outcomes like limb ablation. Pulse examination in these patients is not sensitive to exclude vascular injuries. That often lead to clinicians opting for Computed Tomography Angiogram (CTA) to exclude vascular. this usually leads to a burden in Radiology Department. This study aimed to evaluate the prevalence of vascular injury in patient with orthopaedic injury in the knee. The computed tomography (CT) done in patients with distal femur fracture, knee dislocation and proximal tibia fractures were retrieved from the picture archiving and comunication system (PACS). The CTs were done between June 2017 and June 2022. The computed tomography angiogram (CTA) reports were reviewed to determine cases that vascular injury. A sample size of 511 cases was collected. 386 cases were done CTA and 125 cases were not done CTA. There were 218 tibial plateau fractures, 79 knee dislocations, 72 distal metaphyseal femur fractures, 61 floating knees, 55 distal femure intraarticular and 26 proximal metaphyseal tibia fractures. The mechanisms of injury in these were gunshot, fall from standing height, fall from height, MVA, MBA, PVA and sports. Prevalance was 9.17% (47) of the total injuries in the knee. Prevalance in patients who were sent for CTA was 12.08%. Routine CTA in patients with injuries in the knee is not recomended. The use of ankle brachial index may decrease the number of CTA done

Abstract. Introduction. Total joint arthroplasty (TJA) is one of the commonest and most successful orthopaedic procedures, used for the management of end-stage arthritis. With the recent introduction of robotic assisted joint replacement, Computed Tomography (CT) has become part of required pre-operative planning. The aim of this study is to quantify and characterise incidental CT findings, their clinical significance, and their effect on planned joint arthroplasty. Methodology. All consecutive patients undergoing an elective TJR (hip or knee arthroplasty) were retrospectively identified, over a 3-year period (December 2019 and December 2022). Data documented and analysed included patient demographics, type of joint arthroplasty, CT findings, their clinical significance, as well as potential delays to the planned arthroplasty because of these findings and subsequent further investigation. Results. A total of 624 patients (637 studies, 323 (51.8%) female, 301 (48.2%) male) were identified of which 163 (25.6%) showed incidental findings within the long bones or pelvis. Of these 52 (8.2%) were significant, potentially requiring further management, 32 (5.0%) represented potential malignancy and 4 (0.6%) resulted in a new cancer diagnosis. Conclusion. It is not currently national standard practice to report planning CT imaging as it is deemed an unnecessary expense and burden on radiology services. Within the study cohort 52 (8.2%) of patients had a significant incidental finding that required further investigation or management and 4 (0.6%) had a previously undiagnosed malignancy. In order to avoid the inevitability of a missed malignancy on a planning CT, we must advocate for formal reports in all cases

Aim. Magnetic resonance imaging (MRI) and 2-[. 18. F]-fluoro-2-deoxy-D-glucose (. 18. F-FDG) Positron Emission Tomography, paired with Computed Tomography (PET/CT) are two indicated advanced imaging modalities in the complicated diagnostic work-up of osteomyelitis. PET/MRI is a relatively novel hybrid modality with suggested applications in musculoskeletal infection imaging. The goal of this study was to assess the value of hybrid . 18. F-FDG PET/MRI for chronic osteomyelitis diagnosis and surgical planning. Method. Five suspected chronic osteomyelitis patients underwent a prospective . 18. F-FDG single-injection/dual-imaging protocol with hybrid PET/CT and hybrid PET/MR. Diagnosis and relevant clinical features for the surgeon planning treatment were compared. Subsequently, 36 patients with . 18. F-FDG PET/MRI scans for suspected osteomyelitis were analysed retrospectively. Sensitivity, specificity, and accuracy were determined with the clinical assessment as the ground truth. Standardized uptake values (SUV) were measured and analysed by means of receiver operating characteristics (ROC). Results. The consensus diagnosis was identical for PET/CT and PET/MRI in the prospective cases, with PET/CT missing one clinical feature. The retrospective analysis yielded a sensitivity, specificity, and accuracy of 78%, 100%, and 86% respectively. Area under the ROC curve was .736, .755, and.769 for the SUVmax, target to background ratio, and SUVmax_ratio respectively. These results are in the same range and not statistically different compared to diagnostic value for . 18. F-FDG PET/CT imaging of osteomyelitis in literature. Conclusions. Based on our qualitative comparison, reduced radiation dose, and the diagnostic value that was found, the authors propose . 18. F-FDG PET/MRI as an alternative to . 18. F-FDG PET/CT in osteomyelitis diagnosis, if available

Acetabular morphology and orientation differs from ethnic group to another. Thus, investigating the natural history of the parameters that are used to assess both was a matter of essence. Nevertheless, clarification the picture of normal value in our society was the main aim of this study. However, Acetabular head index (AHI) and center edge angle (CEA) were the most sensitive indicative parameters for acetabular dysplasia. Hence, they were the main variables used in evaluation of acetabular development. A cross-sectional retrospective study that had been done in a tertiary center. Computed tomography abdomen scouts’ radiographs of non-orthopedics patients were included. They had no history of pelvic or hips’ related symptoms or fractures in femur or pelvis. Images’ reports were reviewed to exclude those with tumors in the femur or pelvic bones. A total of 81 patients was included with 51% of them were males. The mean of age was 10.38± 3.96. CEA was measured using Wiberg technique, means of CEA were 33.71±6.53 and 36.50±7.39 for males and females, respectively. Nonetheless, AHI means were 83.81±6.10 and 84.66±4.17 for males and females, respectively. On the other hand, CEA was increasing by a factor 0.26 for each year (3-18, range). In addition, positive significant correlation was detected between CEA and age as found by linear regression r 2 0.460 (f(df1,79) =21.232, P ≤0.0001). Also, Body mass index (BMI) was positively correlated with CEA r 0.410, P 0.004). This study shows that obesity and aging are linked to increased CEA. Each ethnic group has its own normal values that must be studied to avoid premature diagnosis

Total joint arthroplasty (TJA) is one of the commonest and most successful orthopaedic procedures used for the management of end-stage arthritis. With the recent introduction of robotic-assisted joint replacement, Computed tomography (CT) has become part of required pre-operative planning. The aim of this study is to quantify and characterise incidental CT findings, their clinical significance, and their effect on the planned joint arthroplasty. All consecutive patients undergoing an elective TJA (total joint arthroplasty; hip or knee) were retrospectively identified, over a 4-year period (December 2019 and November 2023). Data documented and analysed included patient demographics, type of joint arthroplasty, CT findings, their clinical significance, as well as potential delays to the planned arthroplasty because of these findings and subsequent further investigation. A total of 987 patients (female: 514 patients (52.1%)) undergoing TJA were identified (THA: 444 patients (45.0%); TKA: 400 patients (40.5%); UKA: 143 patients (14.5%)). Incidental findings within imaged areas were identified in 227 patients (23.0%). Of these findings, 74 (7.5%) were significant, requiring further investigation or management, 40 (4.1%) of which represented potential malignancy and 4 (0.4%) resulting in a new cancer diagnosis. A single patient was found to have an aneurysm requiring urgent vascular intervention. Surgery was delayed for further investigation in 4 patients (0.4%). Significant findings were more frequent in THA patients (THA: 43 (9.7%) TKA/UKA: 31 (5.7%). Within our cohort, 74 (7.5%) patients had significant incidental findings that required further investigations or management, with 4 (0.4%) having a previously undiagnosed malignancy. We strongly advocate that all robotic arthroplasty planning CTs are reviewed and reported by a specialist, to avoid missing undiagnosed malignancies and other significant diagnoses

Aims. Management of intra-articular calcaneal fractures remains a debated topic in orthopaedics, with operative fixation often held in reserve due to concerns regarding perioperative morbidity and potential complications. The purpose of this study was to identify the characteristics of patients who developed surgical complications to inform the future stratification of patients best suited to operative treatment for intra-articular calcaneal fractures and those in whom surgery was highly likely to produce an equivocal functional outcome with potential post-operative complications. Methods. All patients who underwent open reduction and internal fixation of calcaneal fractures utilizing the Sinus Tarsi approach between March 2014 and July 2018 were identified using theatre records. Patient imaging was used to assess pre- and post-operative fracture geometry with Computed Tomography (CT) used for pre-operative planning. Each patient's clinical presentation was established through retrospective analysis of medical records. Patients provided verbal consent to participation and patient reported outcome measures were recorded using the Maryland Foot Score. Results. Fifty-eight intra-articular calcaneal fractures (fifty-three patients including five bilateral, mean age = 46.91 years) were included. Forty-nine patients were injured as a result of a fall from a height (92.4%). Mean time from presentation to surgery was 3.23 days (range 0–21). Mean Maryland Foot score was found to be 77.6 (+/− 16.22) in forty-five patients. Five patients (9.4%) had wound complications; two superficial (3.7%) and three deep (5.6%). Conclusion. Intra-articular fractures of the calcaneus should be considered for surgical intervention in order to improve long-term functional outcomes. The Sinus Tarsi approach provides the potential to decrease the operative complication rate whilst maintaining adequate fixation, however, the decision to surgically manage these fractures should be carefully balanced against the risk of post-operative complications. This increased risk of complication associated with smoking may tip the balance against benefit from surgical management