3-dimensional Computed Tomography Reconstruction Research Articles

The influence of radiographic viewing perspective and demographics on the critical shoulder angle

Accurate assessment of the critical shoulder angle (CSA) is important in clinical evaluation of degenerative rotator cuff tears. This study analyzed the influence of radiographic viewing perspective on the CSA, developed a classification system to identify malpositioned radiographs, and assessed the relationship between the CSA and demographic factors. Glenoid height, width, and retroversion were measured on 3-dimensional computed tomography reconstructions of 68 cadaver scapulae. A digitally reconstructed radiograph was aligned perpendicular to the scapular plane, and retroversion was corrected to obtain a true anteroposterior (AP) view. In 10 scapulae, incremental anteversion/retroversion and flexion/extension views were generated. The CSA was measured, and a clinically applicable classification system was developed to detect views with >2° change in CSA vs. true AP view. The average CSA was 33° ± 4°. Intraobserver and interobserver reliability was high (intraclass correlation coefficient ≥ 0.81) but decreased with increasing viewing angle. Views beyond 5° anteversion, 8° retroversion, 15° flexion, and 26° extension resulted in >2° deviation of the CSA compared with the true AP view. The classification system was capable of detecting aberrant viewing perspectives with sensitivity of 95% and specificity of 53%. Correlations between glenoid size and CSA were small (R ≤ 0.3), and CSA did not vary by gender (P = .426) or side (P = .821). The CSA was most susceptible to malposition in anteversion/retroversion. Deviations as little as 5° in anteversion resulted in a CSA >2° from true AP view. A new classification system refines the ability to collect true AP radiographs of the scapula. The CSA was unaffected by demographic factors.

Asymmetric Sternotomy and Sternal Wound Complications: Assessment Using 3-Dimensional Computed Tomography Reconstruction

Wound complications after midline sternotomy result in significant morbidity and mortality. Despite many known risk factors, the influence of sternal asymmetry has largely been ignored. The purpose of this study was to assess the utility of 3-dimensional computed tomographic scan reconstructions to assess sternal asymmetry and determine its relationship with sternal wound infection. A retrospective chart review was conducted for patients who underwent midline sternotomy and received a postoperative computed tomographic scan between 2009 and 2010. Cases were composed of all patients who had a sternal wound infection after undergoing sternotomy. Controls were randomly selected from patients without poststernotomy wound complications. Sternal asymmetry was defined as the difference between the left and the right sternal halves and was expressed as a percentage of the total sternal volume. Twenty-six cases were identified and 32 controls were selected as described earlier. The patients were similar in baseline characteristics and risk factors including age, sex, smoking status, diabetes, chronic obstructive pulmonary disease, preoperative creatinine, and operative time. Univariate factors associated with sternal wound infection include an asymmetry of 10% or greater, body mass index, and internal mammary artery harvest. In a multivariate logistic regression, independent predictors of sternal wound infection included an asymmetry of 10% or greater (odds ratio, 3.6; P = 0.03) and diabetes (odds ratio, 3.3; P = 0.0442). Our data suggest an association between asymmetric sternotomy and sternal wound infections. We recommend an assessment of sternal asymmetry to be performed in patients with sternal wound infection and if it is found to be 10% or greater, the surgeon should implement measures that stabilize the sternum.

Asymmetric Sternotomy and Sternal Wound Complications: Assessment Using 3-Dimensional Computed Tomography Reconstruction

Asymmetric Sternotomy and Sternal Wound Complications: Assessment Using 3-Dimensional Computed Tomography Reconstruction

Evaluating Healing of Allograft Tissues in the Shoulder—Cartilage and Bone

Glenohumeral bone loss and articular defects are often treated by using osseous or osteoarticular allografts. These aid in glenohumeral joint stability and in reconstruction of the native articular surface. Grafts include those such as iliac crest, coracoid, distal tibia, femoral head, or humeral head, depending on the specific surgical pathology. Articular grafts can be further subdivided into viable or nonviable sources. The outcome of grafts that are implemented for stability could be subject to osteolysis, which may portend a poor clinical outcome and recurrent instability. Similarly, grafts required for reconstruction of the articular surface may undergo avascular necrosis, nonunion, and collapse, rendering them useless. The status of these grafts is best assessed with postoperative imaging modalities, which range from plain film radiography to 3-dimensional computed tomography reconstructions. The purpose of this article is to review the current literature regarding the rate of graft resorption, integration, collapse, and union for each of the grafts mentioned using postoperative imaging.

Reexamination of Pelvic Inlet and Outlet Images Using 3-Dimensional Computed Tomography Reconstructions

Inlet and outlet views are essential in the evaluation of patients with pelvic injuries. The optimal angles that should be used to obtain these views are still debated. Computed tomography scans of 70 patients without pelvic ring injuries were analyzed. Using the raw data from the computed tomography images, virtual pelvic x-rays were generated. The images were rotated 1 degree at a time and a total of 360 images were generated. The same procedure was repeated to create solid 3-dimensional (3D) reconstructions. Two trauma-trained orthopaedic surgeons then reviewed all 360 images to select inlet and outlet views as described in previous literature. Intraclass correlation coefficients were calculated for each inlet and outlet value. The average inlet angle (caudal tilt) that was required to achieve a view where the promontory overlaps the S1 body was found to be 26.7 degrees (95% confidence interval, 25-29) with virtual x-rays and 24.3 degrees (95% confidence interval, 22-26) with 3D reconstructions. The average outlet angle (cephalad tilt) that was required to achieve a view where the superior border of the pubic symphysis overlaps the S2 body was 43.7 degrees (95% confidence interval, 42-45) with virtual x-rays and 43.8 degrees (95% confidence interval, 42-45) with 3D reconstructions. There was no difference in these angles based on gender, whereas sacral dysmorphism increased the angle needed to obtain the outlet view by an average of 5 degrees. This study demonstrated that the ideal angle to obtain inlet views should be approximately 25 degrees and to obtain outlet views should be approximately 45 degrees during screening x-rays to evaluate patients who were diagnosed with pelvic injuries. Application of these new values in the clinical practice would provide higher rates of adequate studies and further prospective clinical studies should be performed to validate these parameters.

Endoscopic and Three-Dimensional Radiographic Imaging of the Pterygopalatine and Infratemporal Fossae

We sought to define the surgical endoscopic anatomy of the pterygopalatine fossa (PPF) and infratemporal fossa (ITF) through endoscopic cadaver dissections and radiographic imaging analysis. Eleven fresh cadavers were submitted to computed tomography (CT) and endoscopic dissection. We used 3-dimensional (3-D) CT reconstruction and endoscopic video imaging for analysis of the bony and soft tissue landmarks. One fixed cadaver head was grossly dissected to confirm the endoscopic anatomic findings. The CT and 3-D CT reconstruction measurements between the pterygoid canal and the foramen rotundum averaged 4.36 mm and 5.09 mm, respectively. An osseous ridge (pterygoid ridge) was identified on the anterior face of the pterygoid process as a novel identifiable anatomic landmark in all of the specimens. The average length of the pterygoid ridge on 3-D CT reconstruction was 7.84 mm. The internal maxillary artery entered the PPF posteromedial to the temporalis tendon and anterolateral to the lateral pterygoid muscle. The average distance from the anterior edge of the lateral pterygoid plate to the foramen ovale was 17.1 mm. The pterygoid ridge is a novel and reliable osseous landmark that could assist surgeons during endoscopic surgery on the PPF and ITF. The neurovascular and muscular anatomic relationships were characterized for both the PPF and the ITF.

Anatomical analysis of medial branches of dorsal rami of cervical nerves for radiofrequency thermocoagulation.

Cervical medial branch blocks are used to treat patients with chronic neck pain. The aim of this study was to clarify the anatomical aspects of the cervical medial branches to improve the accuracy and safety of radiofrequency denervation. Twenty cervical specimens were harvested from 20 adult cadavers. The anatomical parameters of the C4-C7 cervical medial branches were measured. The 3-dimensional computed tomography reconstruction images of the bone were also analyzed. Based on cadaveric analysis, most of the cervical dorsal rami gave off 1 medial branch; however, the cervical dorsal rami gave off 2 medial branches in 27%, 15%, 2%, and 0% at the vertebral level C4, C5, C6, and C7, respectively. The diameters of the medial branches varied from 1.0 to 1.2 mm, and the average distance from the notch of inferior articular process to the medial branches was about 2 mm. Most of the bifurcation sites were located at the medial side of the posterior tubercle of the transverse process. On the analysis of 3-dimensional computed tomography reconstruction images, cervical medial branches (C4 to C6) passed through the upper 49% to 53% of a line between the tips of 2 consecutive superior articular processes (anterior line). Also, cervical medial branches passed through the upper 28% to 35% of a line between the midpoints of 2 consecutive facet joints (midline). The present anatomical study may help improve accuracy and safety during radiofrequency denervation of the cervical medial branches.

Frequent Urination Caused by a Giant Iliac Artery Aneurysm

![Figure][1] [![Graphic][3] ][3] An 82-year-old woman with a 10-year history of hypertension presented with a 2-month history of frequent urination. Physical examination revealed a pulsatile mass in the lower abdomen. A 3-dimensional computed tomography reconstruction showed a giant (

Anatomic Localization of Rapid Repetitive Sources in Persistent Atrial Fibrillation: Fusion of Biatrial CT Images With Wave Similarity/Cycle Length Maps

The aim of this study was to investigate the anatomic distribution of critical sources in patients with atrial fibrillation (AF) by fusion of biatrial computed tomography (CT) images with cycle length (CL) and wave similarity (WS) maps. Experimental and clinical studies show that atrial fibrillation (AF) may originate from rapid and repetitive (RR) sources of activation. Localization of RR sources may be crucial for an effective ablation treatment. Atrial electrograms showing rapid and repetitive activations can be identified by combining WS and CL analysis. Patients with persistent AF underwent biatrial electroanatomic mapping and pre-procedural CT cardiac imaging. WS and CL maps were constructed in 17 patients by calculating the degree of repetitiveness of activation waveforms (similarity index [S]) and the cycle length at each atrial site. WS/CL maps were then integrated with biatrial 3-dimensional CT reconstructions by a stochastic approach. Repetitive sources of activation (S ≥ 0.5) were present in most patients with persistent AF (94%) and were mainly located at the pulmonary veins (82% of patients), at the superior caval vein (41%), on the anterior wall of the right atrium (23%), and at the left atrial appendage (23%). Potential driver sources showing both rapid and repetitive activations (CL = 140.7 ± 25.1 ms, S = 0.65 ± 0.15) were present only in a subset of patients (65%) and were confined to the pulmonary vein region (47% of patients) and left atrial appendage (12%). Differently, the repetitive activity of the superior caval vein was characterized by a slow activation rate (CL = 184.7 ± 14.6 ms). The identification and localization of RR sources is feasible by fusion of biatrial anatomic images with WS/CL maps. Potential driver sources are present only in a subset of patients with persistent AF and are mainly located in the pulmonary vein region.

Prediction of coracoid thickness using a glenoid width–based model: implications for bone reconstruction procedures in chronic anterior shoulder instability

Chronic anterior shoulder instability with glenoid bone loss can be a very challenging clinical problem. Significant bone loss is commonly managed with the Latarjet procedure. However, in some cases with severe glenoid bone loss, iliac crest bone grafting is required to obtain a graft of adequate size. Iliac crest bone graft is associated with high rates of donor-site complications. Whereas glenoid dimensions can be determined by use of 3-dimensional computed tomography reconstructions, the thickness of the coracoid cannot be easily measured. This study aims to define a ratio between glenoid width and coracoid thickness that can be used in preoperative planning to determine whether coracoid transfer will yield adequate bone graft to restore glenoid contour or whether iliac crest bone graft must be taken. We studied 100 paired cadaveric scapulae (50 male and 50 female scapulae). The bony dimensions of the coracoid and glenoid were measured for each specimen. Coracoid and glenoid dimensions are provided. The mean thickness of the male coracoid was 35.4% of the width of the glenoid. The mean female coracoid thickness was 34.4% of the glenoid width. A new biomorphologic model is presented to predict coracoid thickness and the ability of the Latarjet procedure to restore stability to a given bone-deficient glenoid. This model may aid the shoulder surgeon in preoperative planning and help promote successful outcomes in glenoid reconstruction surgery by determining whether a Latarjet procedure or iliac crest bone graft is the most appropriate procedure given the predicted amount of coracoid bone graft available.

Pulling on Hyoid Reduces Airway Collapse in Human Cadavers

Objective: This study examined the changes in upper airway dimensions and collapsibility associated with force applied to the hyoid bone using a suture and a novel magnetic system (internal magnet secured to the hyoid and external magnet) in un-fixed human cadavers. Method: Eight cadavers were tested with traction on the hyoid using 1) suture around the hyoid to apply 0.5-5 Newtons of force and 2) a novel magnetic system. Changes in airway dimensions were measured with fluoroscopy and 3-dimensional computed tomography reconstructions. Airway collapsibility was measured using a previously-described flow-based model. Results: A 2N (0.5 lb) force applied to the hyoid bone increased airway dimensions, with greatest effect in the retrolingual region. The anterior direction of traction was more effective than inferior or superior. There was a linear association between the magnitude of force and critical airflow, at 1.5L/min/N (R2 = 0.75). All magnitudes of pull increased the critical airflow ( P < .001). At 2N, the hyoid was advanced 1cm, and the critical airflow was increased 3-fold (3.0 ± 1.71L/min). The magnet system showed similar airway effects to the direct 2N applied force. An increase in upper airway dimensions occurred with inter-magnet distances of 2cm. Conclusion: Forces applied to the hyoid improve upper airway dimensions and collapsibility in the human un-fixed cadaver model. A novel magnet system may represent a promising therapy for treatment of upper airway obstruction in disorders such as obstructive sleep apnea.

Role of Preoperative 3-Dimensional Computed Tomography Reconstruction in Depressed Skull Fractures Treated With Craniectomy

Patients affected by cranial trauma with depressed skull fractures and increased intracranial pressure generally undergo neurosurgical intervention. Because craniotomy and craniectomy remove skull fragments and generate new fracture lines, they complicate forensic examination and sometimes prevent a clear identification of skull fracture etiology. A 3-dimensional reconstruction based on preoperative computed tomography (CT) scans, giving a picture of the injuries before surgical intervention, can help the forensic examiner in identifying skull fracture origin and the means of production.We report the case of a 41-year-old-man presenting at the emergency department with a depressed skull fracture at the vertex and bilateral subdural hemorrhage. The patient underwent 2 neurosurgical interventions (craniotomy and craniectomy) but died after 40 days of hospitalization in an intensive care unit. At autopsy, the absence of various bone fragments did not allow us to establish if the skull had been stricken by a blunt object or had hit the ground with high kinetic energy. To analyze bone injuries before craniectomy, a 3-dimensional CT reconstruction based on preoperative scans was performed. A comparative analysis between autoptic and radiological data allowed us to differentiate surgical from traumatic injuries. Moreover, based on the shape and size of the depressed skull fracture (measured from the CT reformations), we inferred that the man had been stricken by a cylindric blunt object with a diameter of about 3 cm.

Three-dimensional computed tomography for evaluation and management of children with complex chest wall anomalies: useful information or just pretty pictures?

PurposeShaded surface display (SSD) technology, with 3-dimensional computed tomography reconstruction, has been reported in a few small series of patients with congenital or acquired chest wall deformities. Shaded surface display images are visually attractive and educational, but many institutions are hesitant to use these secondary to cost and image data storage concerns. This study was designed to assess the true value of SSD to the patient, family, and operating surgeon, in the evaluation and management of these children. MethodsAfter institutional review board approval, we performed a retrospective review of records of 82 patients with chest wall deformities, evaluated with SSD, from 2002 to 2009. Shaded surface display usefulness, when compared to routine 2-dimensional computed tomography, was graded on a strict numerical scale from 0 (added no value besides education for the patient/family) to 3 (critical for surgical planning and patient management). ResultsThere were 56 males and 26 females. Median age was 15.3 years (range, 0.6-41.1 years). Deformities included 56 pectus excavatum, 19 pectus carinatum, and 8 other/mixed deformities. Six patients also had acquired asphyxiating thoracic dystrophy (AATD). Eleven (13%) had previous chest wall reconstructive surgery. In 25 (30%) patients, SSD was useful or critical. Findings underappreciated on 2-dimensional images included sternal abnormalities (29), rib abnormalities (28), and heterotopic calcifications (7). Shaded surface display changed or influenced operation choice (4), clarified bone vs soft tissue (3), helped clarify AATD (3), and aided in rib graft evaluation (2). Point biserial correlation coefficient analysis (Rpb) displayed significance for SSD usefulness in patients with previous chest repair surgery (Rpb = 0.48, P ≤ .001), AATD (Rpb = 0.34, P = .001), pectus carinatum (Rpb = 0.27, P = .008), and females (Rpb = 0.19, P = .044). ConclusionsShaded surface display, when used to evaluate children and young adults with congenital or acquired chest wall deformities, provides useful or critical information for surgical planning and patient management in almost one third of patients, especially in those requiring a second operation, with acquired asphyxiating thoracic dystrophy, pectus carinatum, and females.

The use of modern imaging techniques in the diagnosis and treatment planning of patients with orbital floor fractures

SummaryBackgroundOcular motility impairment associated with orbital trauma may have several causes and manifest with various clinical symptoms. In some cases orbital reconstructive surgery can be very challenging and the results are often unsatisfactory. The use of modern imaging techniques aids proper diagnosis and surgical planning.Case ReportThe authors present the case of a 29-year-old male who sustained trauma to the left orbit. Orthoptic examination revealed limited supra- and infraduction of the left eye. The patient reported diplopia in upgaze and downgaze with primary position spared. Dynamic magnetic resonance imaging (dMRI) was performed, which revealed restriction of the left inferior rectus muscle in its central section. A patient-specific anatomical model was prepared on the basis of 3-dimensional computed tomography (CT) study of the intact orbit, which was used to prepare a custom pre-bent titanium mesh implant. The patient underwent reconstructive surgery of the orbital floor.ConclusionsModern imaging techniques such as dMRI and 3-dimensional CT reconstruction allow us to better understand the pathophysiology of orbital floor fractures and to precisely plan surgical treatment.

Torticollis of a Specific C1 Dislocation With Split Atlas

A case report. We report a novel case of torticollis disorder because of a congenital split atlas after minor trauma. Torticollis experienced after minor trauma in childhood is usually because of atlantoaxial rotatory fixation, which is a common disorder in pediatric patients and is usually diagnosed with computed tomography (CT). CT scanning with 3-dimensional reconstruction, however, showed a unique rotation of split atlas, a congenital anomaly that presented with torticollis. A female child aged 3 years and 11 months presented to the orthopedic clinic with torticollis after a fall. CT imaging showed no rotatory dislocation of C1-C2. On the 3-dimensional CT reconstruction images, however, anterior and posterior defects in the atlas, the so-called split atlas, and an atypical rotation with malalignment of the posterior arch and asymmetry of the atlantoaxial facet joint were noted. The child was treated with closed reduction using skull traction under general anesthesia. Repositioning of the atlas rotation was confirmed using intraoperative 3-dimensional scanning, and open reduction therapy was avoided. The patient was treated with halo vest for 8 weeks and had full recovery of neck motion with resolution of the torticollis. We present a novel torticollis disorder caused by C1 rotation of a split atlas with closed reduction treatment.

Celiac axis resection for extragastrointestinal stromal tumor

Fig 1. Pre-operative 3-dimensional CT reconstruction. The mass (black arrow) abuts the celiac axis and encases the left gastric artery (white arrow). A 48-YEAR-OLD MAN underwent upper endoscopy for epigastric pain and nausea. Because of endoscopic findings of gastritis and positive biopsy for Helicobacter pylori, he was started on standard triple drug therapy, but failed to respond. His symptoms became more severe and he reported a 10-pound weight loss. Abdominal computed tomography (CT) and magnetic resonance imaging revealed a 3 3 4 cm mass in the gastrohepatic omentum abuting the celiac axis and encasing the left gastric artery (Fig 1). A pre-operative biochemical workup was normal. During exploratory laparotomy, a 5 3 8 cm mass was found to involve the left gastric artery and the celiac axis. Therefore, celiac axis resection was needed to accomplish complete tumor removal (Figs 2 and 3). To test the sufficiency of the collateral blood supply to the liver, a clamp was applied to the common hepatic artery proximal to gastroduodenal artery and proper hepatic artery pulse was verified by Doppler. The tumor was completely mobilized and resected en bloc with the celiac axis. The patient had an uneventful postoperative course with slight elevation of aspartate and alanine aminotransferase levels. Pathologic examination of the specimen demonstrated a mass arranged in solid sheets with myxoid changes and plexiform patterns containing spindle cells with uniform nuclei and ill-defined cytoplasmatic borders. There was no necrosis or lymphovascular invasion. Operative margins were clear of tumor. Immunoperoxidase stains demonstrated positivity for C-kit (CD117), CD34, S-100, and actin. Immunostaining for desmin was negative. The pathologic diagnosis was consistent with extragastrointestinal stromal

Imaging Recognition of Morphological Variants at the Midcarpal Joint

To compare the imaging methods for identifying the various morphological variations of the articular surfaces at the midcarpal joint. Thirteen cadaveric wrists were examined by plain neutral anteroposterior radiographs; 2-dimensional computed tomography (CT); 3-dimensional CT reconstruction, and 3-tesla magnetic resonance imaging (MRI). Carpal measurements were performed, and the parameters that defined the scaphoid, lunate, hamate, and capitate morphological types were investigated, with dissection being used as the definitive measure of morphology. The dissection findings were compared to the results of each imaging technique to determine the accuracy of morphological determination from each technique. Lunate type was the most accurately identified morphological variant amongst all imaging techniques. Lunate type was most accurately determined from coronal MRI. A lunate with a small, cartilaginous ulnar facet (intermediate type) could be differentiated only by coronal MRI and dissection. Scaphoid type could not be determined accurately using any of the imaging modalities described. Capitate type was most accurately determined from coronal MRI. However, flat and spherical-type capitates could not be routinely differentiated from V-shaped capitates. Hamate type was most accurately determined from 3-dimensional CT reconstruction. Accurate identification of carpal bone morphology is required to improve our understanding of carpal mechanics and pathology. Not all morphological features can be identified radiographically. Direct visualization is required to differentiate types of scaphoid, and to differentiate V-type capitates. MRI provides the most accurate identification of lunate type, and 3-dimensional CT provides the best method of differentiating hamate types.

Relationship Between Screw Trajectory of C1 Lateral Mass Screw and Internal Carotid Artery

Evaluation of diagnostic imaging. To comprehend anatomic relationships between the internal carotid artery (ICA) and bicortical purchase of C1 lateral mass screws from the perspective of avoiding ICA injury. No studies have evaluated safety trajectory of atlantal lateral mass screw that would avoid the ICA injury in relation to its location, although previous studies have indicated concern about ICA injury by the screw tip at the anterior surface of the lateral mass of the atlas. From 149 of 177 human 3-dimensional computed tomography reconstruction images, 6 distance and 2 angle parameters related to both atlas and ICA were measured on the plane 15 degrees cephalad to the transverse plane. In addition, angle of error during screw insertion from intended trajectory was checked. The ICA was located in front of the C1 lateral mass in 64.4% of cases and faced the lateral one third of the C1 lateral mass in 54.6% of cases. None were located in front of the medial one third of the C1 lateral mass. The maximum inward screw trajectory that would violate the ICA was 8.6 degrees . Mean angle of preoperative C1/2 rotation and angle of error from intended trajectory was about 5 degrees , respectively. The possibility of ICA injury can be excluded by correct insertion of the screw 10 degrees inward. Although bicortical purchase with adequately medially angulated trajectory might be safe enough, we must remember the possibility to violate the ICA in bicortical purchase, because the intended screw trajectory never be assured.

Use of 3-Dimensional Computed Tomography Reconstruction Studies in the Preoperative Assessment of Patients Undergoing Balloon Dilatation for Tracheobronchial Stenosis

Background: Balloon dilatation (BD) is a useful method of treating tracheobronchial stenosis (TBS); however, accurate preoperative identification of the lesion is difficult. Three-dimensional computed tomography (3D-CT) is an imaging method that may allow more accurate definition of the lesion(s) preoperatively. Study Objective: It is the aim of this study to present our finding using 3D-CT as a part of the preoperative evaluation of patients with TBS undergoing BD. Methods: We studied a prospective case series of 17 consecutive patients who underwent 29 BDs for TBS from a variety of benign and malignant causes at a tertiary care hospital. All patients had a preoperative spiral CT; these data were processed by a software program, VIDA, which was developed at this institution, and 3D-CT reconstruction images of the TBS were created. This enabled accurate preoperative anatomic definition of the lesion. The patients subsequently underwent BD. Results: All 17 patients had lesions identified with 3D-CT. Six patients had tracheal lesions and 12 patients had main stem lesions. One patient had combined tracheal and main stem lesions and 2 other patients had bilateral main stem lesions. Nine out of 17 patients required only one BD. One patient had a failed BD. The remaining 6 patients required more than one BD for optimal results (up to a maximum of 4). The follow-up period ranged from 1 to 34 months. Conclusions: 3D-CT offers accurate definition of TBS, including anatomic location, number of lesions present and status of airway distal to lesion. In this study, all preoperative lesions were correctly identified prior to BD.

Accuracy of anterior cruciate ligament tunnel placement with an active robotic system: A cadaveric study

Purpose: The objective of this study was to evaluate the accuracy of tunnel placement for ACL reconstruction performed with an active robotic system. Type of Study: Cadaveric analysis. Methods: A reference screw containing 4 fiducials was placed in the femur and tibia of 13 fresh-frozen cadaveric knees. A preoperative plan was developed using images from 3-dimensional computed tomography reconstructions of the knee. The active robotic system then drilled the tunnels. The location and direction of each planned tunnel in the femur and tibia were determined from the preoperative plan. To compare these parameters postoperatively, a mechanical digitizer and a tunnel plug were used. The deviation in location and direction between the planned and drilled tunnel was determined. Results: In preliminary trials, the tibial tunnel was located inaccurately because slippage of the drill bit occurred on the bone at the start of tunnel drilling. This was minimized by decreasing the feed rate of the robot by 75%. For the remaining 10 knees, deviations with respect to the preoperative plan were found of 2.0 ± 1.2 mm and 1.1° ± 0.7° for the intra- articular tibial tunnel location and direction, respectively. For the femur, the deviations were 1.3 ± 0.9 mm for the tunnel location (intra-articular) and 1.0° ± 0.6° for the tunnel direction. Conclusions: The active robotic system is highly accurate for tunnel placement during ACL reconstruction, meaning that the robot drills the tunnels very close to the surgeon’s plan. Comparison to a control group of surgeons could not be made because no preoperative plan is usually created in traditional surgery. However, accuracy values in this study were found to be below the values for precision of repeated tunnel placements reported in the literature.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 9 (November- December), 2002: pp 968–973