Penetration Of Cortex Research Articles

A Simple and Low-cost Drilling Simulator for Training Plunging Distance Among Orthopedic Surgery Residents

Drilling through bone is a complex action that requires precise motor skills of an orthopedic surgeon. In order to minimize plunging and soft tissue damage, the surgeon must halt drill progression precisely following penetration of the far cortex. The purpose of this study was to create a low-cost and easy-to-use drilling simulator to train orthopedic residents in reducing the drill plunging depth. This prospective observational study was performed in the division of orthopedic surgery of a single tertiary medical center. The participants included 13 residents and 7 orthopedic specialists. The simulator consisted of a synthetic femur bone model and ordinary modeling clay, and the training unit consisted of a disposable plastic tube (∼US$14), clamps (∼US$58), and a power drill + drill bit (standard hospital equipment). Plunging depths were measured by the simulator and compared between orthopedic specialists, the 6 "senior residents" (3+ years) and the 7 "junior residents" during a training session. Measurements were taken again 2 weeks following the training session. Initially, the plunging depths of the junior residents were significantly greater compared to those of the orthopedic specialists (7.00 mm vs. 5.28 mm, respectively, p < 0.038). There was no similarly significant difference between the senior residents and the orthopedic experts ([6.33 mm vs. 5.28 mm, respectively; p = 0.18). The senior residents achieved plunging depths of 5.17 mm at the end of the training session and 4.7 mm 2 weeks later compared to 7.14 mm at the end of the training session and 6 mm 2 weeks later for the junior residents. This study demonstrated the capability of a low-cost drilling simulator as a training model for reducing the plunging depth during the drilling of bone and soft tissue among junior and senior residents.

Analysis of Computed Tomography Scan After Anterior Odontoid Screw Fixation with the Herbert Screw: Is It Effective to Reduce Fracture Gap?

To assess computed tomography scans to evaluate the extent of reduction of fracture displacement and fracture gap after anterior odontoid screw fixation using the Herbert screw. Thirty-seven odontoid fractures were reduced and treated by anterior odontoid screw fixation with the Herbert screw. There were 37 patients whose age ranged from 20 to 79 years. Three-dimensional computed tomography scans were obtained for all patients to assess the screw position, the presence of the penetration of superior cortex of dens, the extent of reduction of fracture displacement, and fracture gap. Mean fracture displacement was 2.6 ± 3.2 mm before surgery; after the operation this value was 1.0 ± 1.5 mm. The difference in fracture gap between the preoperative and the postoperative state was -0.1 ± 1.1 mm, which was not statistically significant (P= 0.667). We achieved cortical purchase in only 16 of 37 patients (43.2%); cortical purchase was not obtained in 21 patients (56.7%) due to the fear of the risk of the damage of neural and vascular structures. Of these 21 patients who had no penetration of the superior cortex of dens, widening of the fracture gap occurred in 12 patients (57%), no change in 6 patients (29%), and there was shortening in 3 patients (14%). However, of the 16 patients with penetration of apical dens tip, we achieved significant reduction of fracture gap (P= 0.002). To maximize reduction of fracture gap using the Herbert screw, it is essential to penetrate the apical dens tip.

Ultrasonography or direct radiography? A comparison of two techniques to detect dorsal screw penetration after volar plate fixation

BackgroundComplications related to extensor tendons have begun to increase with the use of volar plates in the treatment of distal radius fractures. In this study, we aimed to compare four-plane radiography and ultrasonography in the evaluation of dorsal cortex screw penetration following volar plate fixation.MethodsWe recruited 47 patients (33 males, 14 females, mean age 37.4 years; range 18–58 years). To evaluate dorsal screw penetration in all patients, we performed radiographs at 45° pronation, 45° supination and obtained dorsal tangential graphs at maximum palmar flexion, and a wrist lateral radiograph. Wrist ultrasonography was performed in all patients.ResultsDorsal screw penetration was detected in 12 of the 47 patients undergoing VLP application. While there was > 2 mm screw penetration in seven patients, there was < 2 mm screw penetration in five patients. On four-plane radiographs, screw penetration > 2 mm was detected in seven patients and screw penetration < 2 mm was detected in two patients. On four-plane radiography, dorsal screw penetration was not detected in three out of five patients, who were shown to have < 2 mm screw penetration by ultrasonography. In addition to perioperative four-plane radiographs are also required to detect dorsal cortex penetration in patients undergoing VLP due to distal radius fracture. However, the detection of screw penetrations < 2 mm is more likely with ultrasonography compared to four-plane radiography.ConclusionWe recommend that dorsal cortex screw penetration should be evaluated with perioperative ultrasonography.Trial registrationResearch Registry, researchregistry3344, Registered 10 January 2017

High incidence of screw penetration in the proximal and distal tibiofibular joints after intramedullary nailing of tibial fractures—A prospective cohort and mapping study

BackgroundIntramedullary-nails (IMN) are the treatment of choice for most tibial shaft fractures due to their minimally-invasive nature and non-demanding surgical technique. However, a potential iatrogenic pitfall is intra-articular interlocking screw positioning within the proximal (PTFJ) and distal (DTFJ) tibiofibular joints that may go unrecognized. ObjectiveTo evaluate the incidence of intra-articular screw penetration of the PTFJ and DTFJs after interlocking of IMN for tibial fractures. InterventionReamed IMN using modern techniques, including proximal interlocking via standard aiming jig and distal interlocking either freehand or using SureShot®. MethodsProspective series of 165 consecutive patients with a tibial shaft fracture managed with an IMN. Diagnosis and incidence of penetration of the PTFJ and DTFJ was assessed on protocolled low-dose postoperative CT-scans (standardized clinical practice for assessing rotational alignment). The degree of penetration of the TFJ’s was graded as: Grade 1–slight breach of the tibial cortex; Grade 2–clear penetration of the tibial cortex with intra-articular screw tip; and Grade 3–penetration of both tibial- and fibular cortices with screw tip in fibula. ResultsOf the 165 tibial shaft fractures, using the AO/OTA classification, 69% were simple, 16% wedge and 15% complex fractures. Following IMN 42% of patients had intra-articular screw penetration of their PTFJ whilst 39% had penetration of their DTFJ. 66% of patients had penetration of either one- or both of their TFJs. The grading of PTFJ violation was distributed as follows: Grade 1 in 24 patients; Grade 2 in 26 patients and Grade 3 in 19 patients. DTFJ violation was graded as: Grade 1 in 21 patients; 40 patients had Grade 2 violation; and four patients had a Grade 3 penetration. ConclusionsThis diagnostic imaging study reports a high rate of intra-articular screw penetration of the PTFJ and DTFJ after interlocking of IMN for tibia shaft fractures. A prospective cohort study is underway to evaluate its clinical significance.Changes to enable alteration in forced angle of interlocking screw trajectory and avoidance of the anteromedial to posterolateral locking screw may reduce the incidence of TJF violation. Level of evidenceLevel II – Diagnostic Imaging Study

Novel Technique for Fixation of Medial Malleolus Fractures

Category: Ankle, Trauma Introduction/Purpose: The traditional method for fixation of medial malleolar fractures has been with partially threaded (PT) lag screws extending beyond the physeal scar. Recent studies have shown fully threaded (FT) bicortical fixation in the tibial metaphysis provides superior biomechanical, radiographic and clinical outcomes. Risks with the bicortical technique include drill bit breakage, as well as injury to structures lateral to the tibial metaphysis if the far cortex is overdrilled. We hypothesized that far endosteal fixation, without penetration of the far cortex, would provide increased biomechanical strength compared to traditional PT lag screw fixation, while minimizing the risks associated with bicortical fixation. Methods: Twelve matched pairs of cadaver ankles were harvested and an oscillating saw was used to make an osteotomy at a 45- degree angle to the axilla. The medial malleolus was then re-approximated and held in the correct orientation using two kirschner wires. A 2.7 mm drill bit was used to drill a unicortical pilot hole perpendicular to the osteotomy. The left ankle was used for all PT 3.5 mm cancellous screws and all screw lengths were 45 mm. For the contralateral ankle, the 2.7 mm drill bit was used to drill to the lateral tibial cortex. The depth gauge was then used and five millimeters was added to the measured number to achieve endosteal purchase with the appropriate FT screw. Screw lengths varied in size from 55-70 mm. Screws were then placed using a torque measuring screw driver and final torque was recorded. Finally, radiographs were taken to confirm appropriate placement. Results: Average torque for unicortical PT cancellous screws was 5.02 inch-pounds with a standard deviation of 2.34. Average torque for all FT cortical screws was 7.63 inch-pounds with a standard deviation of 3.86 (Fig. 1A). A paired student’s t-test was performed comparing both fixation methods and the measured P-value was &lt;0.01. Visual and radiographic inspection revealed no displacement of the fracture site using the FT endosteal screw (Fig. 1C). Conclusion: Our results indicate superior biomechanical torque with far endosteal fixation as compared to a traditional PT lag screw, while minimizing risks associated with bicortical fixation. This novel technique may provide added strength with minimal risk in vivo. Further clinical studies comparing radiographic results and outcomes of far endosteal fixation versus bicortical fixation are needed to ascertain the value of this fixation technique for medial malleolus fractures.

Application value of carpal shoot through view in the palmar plating of distal radius fractures

Objective To explore the application value of carpal shoot through view in the palmar plating of distal radius fractures. Methods From March 2015 to May 2016, there were 62 acute distal radius fractures received various operation in our department, in which 48 patients were only performed volar locked plating. Among these 48 cases, there were 21 males and 27 fe-males, with ages ranging from 17 to 75 years (mean 43.6±10.6 years). There were 15 cases of type A, 11 cases of type B and 22 cas-es of type C distal radial fractures according to AO/OTA classification. All the operations were performed through modified Hen-ry's approach between the radial artery and flexor carpi radialis. Once achieved satisfactory reduction, we performed rigid fixation of distal radius using anatomical locking plates. In all cases, bicortical drilling was performed. Screw lengths selected measured 1 to 2 mm less than the depth gauge number avoiding dorsal cortex penetration. After plate fixation of these 48 cases, standard pos-teroanterior and lateral radiographs were taken followed by the carpal shoot through view. To obtain carpal shoot through view, the patient's forearm was maximally supinated, the elbow flexed about 60°-70°and the wrist maximally dorsiflexed. The image intensi-fier beam is directed over the base of the thenar eminence. Compare the ratio of dorsal protrusion between standard view and car-pal shoot through view, then statistical analysis was performed. After operation, CT scan was routinely taken to further test the ef-fectiveness of carpal shoot through view. Results Five cases were detected dorsal cortex screw protrusion using standard postero-anterior and lateral views (10.4%, 5/48). There were totally 16 cases (including the former 5 cases) of dorsal screw penetration un-covered by the carpal shoot through view (33.3%, 16/48. Statistically significant difference was existed between the two fluorosco-py methods. Additionally, in 2 cases, a screw had penetrated the distal radioulnar joint (DRUJ), which was only apparent on the shoot through view. All the improper screws were exchanged and again were verified by the carpal shoot through view. The overall screw exchange rate was 37.5% (18/48). Conclusion Compared with standard AP and lateral fluoroscopy, the carpal shoot through view can reliably reveals dorsal screw penetration. Meanwhile, it provides excellent visualization of DRUJ. Key words: Radius fractures; Fracture fixation, internal; Bone screws; Fluoroscopy

Fluoroscopic Confirmation of Sacral Pedicle Screw Placement Utilizing Pelvic Inlet and Outlet Technique: Technical Note.

Minimally invasive surgical techniques may decrease length of stay, operative duration and blood loss, and postoperative pain. Numerous technical challenges and concerns surround the placement of percutaneous pedicle screws at the lumbosacral level. Maximization of screw triangulation, bicortical purchase, and rostral bias toward the sacral promontory has been shown repeatedly to stabilize lumbosacral segment instrumentation and maximize pullout strength. Because of the unique anatomy, conventional anteroposterior (AP) and lateral radiographic views are relatively less reliable at determining screw depth and penetration of the sacral cortex. Percutaneous sacral pedicle fixation using AP and lateral 2-dimensional fluoroscopy is complicated by the variable contour of the sacral alae and promontory. The pelvic inlet view is ideal for visualization of the ventral screw extent and is obtained by directing 45-degree cephalad and 0-degree mediolateral, with adjustments aligning the patient's pelvic brim. The modified pelvic outlet view is obtained with the trajectory axis being directed 45-degree caudal from the AP plane. This aligns the pubic symphysis with the second sacral vertebrae providing visualization of the superior boundary of the S1-bony neural foramen and any inferior wall pedicle breaches. The authors describe this reliable fluoroscopic technique and their clinical experience with percutaneous S1-screw placement.

Detection of penetration of the dorsal cortex by epiphyseal screws of distal radius volar plates: Anatomical study comparing ultrasound and fluoroscopy

HypothesisOsteosynthesis of the distal radius by a volar plate can be complicated by lesions of extensor tendons by screws penetrating the dorsal cortex. The fluoroscopic skyline view enables to confirm the length of the screws. To avoid its risk of irradiation, some authors have recommended using ultrasound instead. Material and methodsThe goal of this study was to demonstrate that the detection rate of screws penetrating the dorsal cortex was at least as good using ultrasound compared to fluoroscopic skyline. A volar plate in which one screw penetrated the dorsal cortex was implanted in 10 cadaveric wrists. Three observers had to detect which screw penetrated the dorsal cortex using ultrasound and then a fluoroscopic skyline. ResultsThe detection rate of screws penetrating the dorsal cortex was 43.33% with ultrasound and 96.97% using the fluoroscopic skyline. Agreement between the observers was poor with ultrasound and good with fluoroscopy. ConclusionOur results show that ultrasound cannot replace the fluoroscopic skyline view to detect screws penetrating the dorsal cortex of the distal radius in clinical practice. Level of evidenceII.

Use and modifications of cervical and upper thoracic laminar screws in posterior stabilization.

Laminar screw technique is used to stabilize C2 and other levels when other techniques cannot be performed. The patients underwent laminar screws at cervical and upper thoracic levels in our clinic during 5 yearswere evaluated retrospectively. In 25 patients, 6 to 82 years old,total 54 laminar screws were used. Most frequent diagnoses were cervical spinal stenosis and craniovertebraljunction anomalies.There were handicaps to perform other type of screwsin 19 out of 25 screws during first 4 years, and 9 out of 29 in the last year (p=0.0009).Two modifications were performed in some cases. In 4 segments with thin lamina, a shorter screw was performed to leave clear the thinnest part, and in 3 C2 levels with almost full length bifid spinous process,shorter screws were inserted from medial sides of the bifid processes with a more vertical orientation. There was ventral cortex penetration in 11 screws without new neurological deficits. One of them was removed because of its full thickness insertion into the spinal canal.Fusion rate was 75% in 16 patients followed radiologically longer than 6 months.In one patient out of 4 without fusion, unilateral screw was loosened, and in others laminar screws were not loosened. Laminar screw technique is easy, safe and effective at C2, C7 and upper thoracic levels. Some modifications may be required due to the anatomical variations.It can be used at other subaxial levels also in theselected cases that other techniques could not be performed.

Biomechanical Comparison of Bicortical, Unicortical, and Unicortical Far-Cortex–Abutting Screw Fixations in Plated Comminuted Midshaft Clavicle Fractures

The objective of this study was to assess the biomechanical properties of bicortical locking screws, unicortical locking screws, and unicortical far-cortex-abutting locking screw fixation in a cadaver model of comminuted midshaft clavicle fractures stabilized with a locking plate placed on the superior surface of the clavicle. Nine pairs of adult fresh-frozen cadaver clavicles were allocated into 3 groups for either bicortical, unicortical, or unicortical far-cortex-abutting locking plate fixation. After a 1-cm osteotomy to simulate a comminuted fracture and instrumentation with an 8-hole locking plate placed on the superior surface of the clavicle, the specimens were mounted in a custom dual-gimbal fixture in a materials-testing system and tested in axial compression, torsional, and torsional load to failure. Axial stiffness and axial osteotomy site stiffness did not demonstrate differences between constructs. In cyclical torsion, both the bicortical and the unicortical far-cortex-abutting constructs were significantly stiffer than the unicortical construct. For torsional failure stiffness, both the bicortical and the unicortical far-cortex-abutting constructs were significantly stiffer than the unicortical construct. There was no difference between bicortical and unicortical far-cortex-abutting for torsional failure stiffness. The bicortical construct exhibited significantly higher peak failure torque compared with the unicortical construct. Unicortical far-cortex-abutting locking screw fixation provides comparable mechanical properties under axial and torsional loads to bicortical fixation, without penetrating the far cortex. Unicortical far-cortex-abutting locking screw fixation obviates far cortex penetration, and thereby protects nearby anatomical structures, may ease symptomatic implant removal, alleviates refracture risk, and eases conversion to bicortical fixation in the case of revision surgery.

Challenges in the use of intraosseous access.

Challenges in the use of intraosseous access.

Dorsal Screw Penetration With the Use of Volar Plating of Distal Radius Fractures

To evaluate the most vulnerable position at which volar plate screws may penetrate the dorsal cortex of the radius and to determine which specific intraoperative fluoroscopic images (lateral, 45 degrees supination, 45 degrees pronation, and dorsal tangential) are most useful to detect dorsal cortex penetration. Four 2.5-mm locking screws were inserted distally using 18-, 20-, or 22-mm screws in 7 cadaveric specimens apiece. The specimens were then evaluated to count the number of screws breaching the dorsal cortex and the amount of penetration. Lateral, 45 degrees supination, 45 degrees pronation, and dorsal tangential fluoroscopic views were taken of each wrist. Sixty-three orthopaedic surgeons of varying experience were then asked to evaluate whether the screws penetrated the dorsal cortex after viewing each image. Dorsal cortex screw penetration of at least 1 screw occurred in 3.6% of specimens with 18-mm screws, 25% of specimens with 20-mm screws, and 57% specimens with 22-mm screws. Radial-sided screws more commonly breached the dorsal cortex. The sensitivity was 58% on the lateral view, 88% on the 45 degrees supination view, 53% on the 45 degrees pronation view, and 67% on the dorsal tangential view. Additionally, surgeons with more experience were less accurate in detecting prominent screws. Clinicians should consider use of these views to evaluate dorsal screw penetration after volar plating but may opt to subtract a few millimeters from their measured screw lengths to avoid over penetration past the dorsal cortex.

135 Sternal Flow Rates and Insertion Success Using a Multisite Intraosseous Device

135 Sternal Flow Rates and Insertion Success Using a Multisite Intraosseous Device

Cephalomedullary nails: factors associated with impingement of the anterior cortex of the femur in a Hispanic population.

Impingement and penetration of the anterior cortex of the femur have been reported as complications after cephalomedullary nailing. The purpose of this study was to determine factors related to nail impingement in our population of Hispanic patients. A non-matched case-control study was carried out and 156 patients who underwent cephalomedullary nailing from 2010 and 2013 were included; 78 cases with anterior cortical impingement and 78 control cases without impingement were documented. Demographic variables and specifications of the nails such as manufacture and radius of curvature were recorded. The presence of impingement, angle of incidence on radiographs--indirect measurement of the femoral bow on the sagittal plane--and nail entry site were determined. Bivariate and multivariate logistic regression analyses were performed to identify the factors associated with cortical impingement. The distribution by sex corresponded to 87 females (56%) and 69 males (44%) with a mean age of 75 years [SD 18.2]. Cortical impingement was presented in 78 cases (50%) and 6 (3.8%) patients evidenced penetration of the anterior cortex of the femur. On the bivariate analysis the posterior nail start site is highlighted, which showed a positive association with impingement (OR 4.3; 95% CI 1.1-36 and p = 0.04). After the multivariate analysis, the factors associated with anterior cortical impingement included female gender (OR 2.2; 95 % CI 1.1-4.6 and p ≤ 0.038), straight nails-short nails-(OR 4.9; 95% CI 2.2-10 and p ≤ 0.001) and angle of incidence ≥7° (OR 4.9; 95% CI 2.2-10 and p ≤ 0.001), the latter showing a likelihood of 57 % for impingement, increasing to 90% with an angle of incidence of 11°. Posterior entry site should be avoided and an anterior site should be used. Female gender, straight nails and greater angle of incidence of the femur were associated with cortical impingement. A specific intramedullary nail design is needed for the Hispanic population due to high impingement and anterior cortical penetration rates seen with conventional nails. Short curved nails and long nails with a lower radius of curvature are required.

Screw length in volar locking plate fixation for distal radial fractures.

To develop a reference for the distal screw length in volar locking plate fixation for distal radial fractures in an East Asian population. 12 pairs of forearm specimens from 11 male and one female East Asian cadavers were scanned using computed tomography. On sagittal images of the distal radius, the mean cortex-to-cortex distance of 8 quadrants was measured as a reference for the distal screw length. In addition, intra-operative 3-dimensional fluoroscopy of 10 male and 10 female patients who underwent volar locking plate fixation for distal radial fractures was used to validate the distal screw length in the cadaveric reference. 76 distal locking screws were applied in the 8 quadrants; their cortex-to-cortex distances were measured. The mean cortex-to-cortex distances at quadrants A, B, C, D, E, F, G, and H were 15.4 mm, 19.6 mm, 20.8 mm, 20.0 mm, 13.3 mm, 18.0 mm, 18.8 mm, and 17.4 mm, respectively. In 45% of the specimens, the 2 screws inserted at quadrants C and D were longest. Distal screws (quadrants A to D) were significantly longer than proximal screws (quadrants E to H) [p=0.02]. In intra-operative 3-dimensional fluoroscopic images, 2 of the 76 distal locking screws penetrated the dorsal cortex (one in quadrant A and one in quadrant F). The mean screw length was 88.0% of the cortex-to-cortex distance. Referenced to the cadaveric data, 88.2% of the screws could be safely inserted without penetrating the dorsal cortex, and the remaining 11.8% of screws (5 at quadrant D, one at quadrant B, and 3 at quadrant C; all in female patients) could potentially cause dorsal cortex penetration of 2 to 4 mm. In male patients, the mean screw length was 76.1% of the cortex-to-cortex distance based on the cadaveric reference. In female patients, when the screw length was 4 mm less than the cadaveric reference, the mean screw length would be 72.0% of the referenced cortex-to-cortex distance, with no dorsal cortex penetration. In female patients, the screw length should be 4 mm less than the cadaveric reference to avoid dorsal cortex penetration.

Avoiding complication of volar locked plates

Volar locking plates are designed to improve and maintain anatomic alignment, even in patients with dorsal comminution and poor metaphyseal bone quality. Its widespread use led to specific complications. Most part is related to tendon, nerve and complex regional pain syndrome [1] and could be avoided by meticulous attention to detail and surgical experience [2]. Tendon and articular injury complications can be prevented by careful avoidance of dorsal cortex and intraarticular screw penetration, use of the low profile plates, and careful placement of the plate proximal to the watershed line. Most frequent tendons affected are Extensor Policis Longus (EPL) and Flexor Policis Longus (FPL). EPL tendon rupture can occur after a distal radius fractures even when not fixed by a plate [3]. Use of standard intraoperative fluoroscopy imaging is crucial to assess dorsal cortex screw penetration. Lister tubercle can mask prominent screws tips and lateral images have limited sensibility particularly among less experienced observers and for the evaluation of the most ulnar screw positions [4]. Irritation or rupture of flexor tendons, especially the FPL, depends on the position of the plate [5]. Assessment of articular penetration of the screws is critical. Routine use of articular views [6], as well as a 45° pronated oblique view [7] in doubtful cases, is mandatory during placement of each screw. Postoperative nerve dysfunction is one of the most common complications, especially median nerve dysfunction [1]. K-wires used for provisional and supplementary fixation can be a source of complications. Such complication may be caused by superficial radial nerve irritation due to K-wire placement during fracture reduction. Finally, loss of reduction due to inadequate screw length or very osteoporotic bone may lead to symptomatic malunion. In extra-articular fractures, a minimum of four locked unicortical distal screws [8] of at least 75% length produce construct stiffness similar to bicortical fixation and should be considered to avoid extensor tendon injury [9]. This is not the case when there are dorsal unstable articular fragments that can displace afterwards. Once the fracture is healed, plates and screws are not necessary anymore and their removal can be indicated or suggested as a prophylactic measure, as this procedure is usually not associated with complications [10].

Axial perspective to find the largest intraosseous space available for percutaneous screw fixation of fractures of the acetabular anterior column.

To find the largest screw path in the acetabular anterior column using a novel method of axial perspective and test the clinical feasibility of the anterior column axial view projection. 3D models with the inner triangular patches deleted were created from the pelvic CT scan data of 58 normal pelvises. The transparency of each 3D model was downgraded at the axial perspective (the view perpendicular to the cross section of the anterior column axis) so that a translucent area was seen clearly. The orientations of each 3D model were adjusted until a triangle-like translucent area that could accommodate the largest virtual screw (Screw I) was present and then an ellipse-like translucent area that could accommodate the two largest virtual screws (Screw II) was present. The maximum diameter, direction of Screw I and the maximum diameter Screw II were measured. Clinical feasibility of the axial view projection was next tested in five cadaveric specimens. The mean maximum diameters of Screw I and Screw II were 11.20 ± 1.73 (7.80-14.60 mm) and 8.71 ± 0.91 (6.60-10.60 mm), respectively. The angles of Screw I to the transverse, coronal and sagittal planes were 41.16° ± 4.59°, 18.18° ± 1.15° and 44.33° ± 4.31°, respectively. Translucent areas were successfully observed in all the cadaveric hemi-pelves and guide pins were successfully inserted in all the cadaveric hemi-pelves with the assistance of the anterior column axial view projection without cortex penetration or joint violation. The acetabular anterior column could safely accommodate not only one 7.3-mm screw, but also two 6.5-mm screws. The anterior column axial projection may be clinically feasible.

Safe and successful bone marrow biopsy: an anatomical and CT-based cadaver study.

Bone marrow biopsy is generally a safe procedure. However, infrequently the procedure is associated with serious injuries that are attributed to inadvertent needle penetration of the iliac bone's inner cortex. An evidence-based approach to needle orientation during iliac crest biopsy does not exist. In our study, the posterior to anterior path of the bone marrow needle from the posterior superior iliac spine (PSIS) was studied in human cadavers in two orientations: (1) perpendicularly to the coronal plane (the perpendicular approach) and (2) laterally toward the ipsilateral anterior superior iliac spine (ASIS) (the lateral approach). The biopsy needle was deliberately advanced through the inner ilial cortex in both approaches. Dissections and imaging studies were done to identify the relationship of the penetrating needle to internal structures. Both approaches begin with a perpendicular puncture of the outer cortex at the PSIS. The perpendicular approach proceeds anteriorly whereas in the lateral approach the needle is reoriented toward the ipsilateral ASIS before advancing. The lateral approach caused less damage to neurovascular structures and avoided the sacroiliac joint compared to the perpendicular approach. This procedure is best done in the lateral decubitus position. Proper use of the lateral approach should obviate many of the complications reported in the literature.

Scaphoid Nonunions Treated With 2 Headless Compression Screws and Bone Grafting

To evaluate union and complication rates associated with the use of 2 headless compression screws and bone grafting for the treatment of scaphoid nonunions. A total of 19 patients (18 male and 1 female) at an average age of 21 years were treated with open reduction and internal fixation with 2 cannulated, headless, compression screws for scaphoid nonunions. Bone grafting techniques included corticocancellous autograft from the iliac crest in 14 patients, capsular-based vascularized distal radius graft in 3, and medial femoral condyle free vascularized bone graft in 2. Patients were treated an average 19 months after the injury. Fracture nonunions were at the waist (n= 12), proximal third (n= 5), or distal third (n= 2) of the scaphoid. Dorsal (n= 7) and volar (n= 12) surgical approaches were used. All fractures had clinical and radiographic evidence of bone union at an average of 3.6 months. Postoperative computed tomography scans were available in 13 patients and showed union without evidence of screw penetration of the scaphoid cortex. No complications occurred in this series, and no revision procedures have been necessary. Our results indicate that the use of 2 headless compression screws for the treatment of scaphoid nonunions is safe and effective. A variety of bone grafting techniques can be used with this technique. The use of 2 compression screws may provide superior biomechanical stability and ultimately improve outcomes measured with future long-term comparative studies. Therapeutic IV.

Clinical and Computed Tomographic Evaluation of Safety and Efficacy of Facet Screw Fixation in the Subaxial Cervical Spine

A retrospective study comparing screw positioning and associated complications between 2 different facet screw placement methods. To review the anatomic location, clinical safety, efficacy, and limitations of 2 facet screw placement techniques. Facet screw fixation in the subaxial cervical spine penetrates 4 cortical layers and affords better stability than lateral mass screws. Takayasu and colleagues recommended placing screws in the sagittal plane. We modified the trajectory to direct the screws laterally from the sagittal plane to place the root at less risk and improve fixation by increasing the excursion of the screws into bone. No clinical reports exist describing the quadricortical facet screw placed in a lateral direction. A total of 95 screws were used in 18 consecutive patients who underwent posterior cervical stabilization for various spinal disorders: 34 screws used sagittal plane screw placement and 61 used our technique. Screw-related complications were reviewed. Screw trajectories and screw tip positions related to the ventral cortical margin and vertebral artery were evaluated using postoperative 3-dimensional computed tomograms taken within 6 months after surgery. Instrumentation failures were evaluated from postoperative 3-dimensional computed tomograms taken 2 years after surgery. There was 1 complication, nerve root irritation due to screw malposition. Postoperative computed tomographic images revealed that drilling was 30 degrees lateral from the sagittal plane in our method. Fourth cortex penetration failed in 29% of the screws placed in the sagittal plane and in 5% by our method. Screw loosening was significantly increased using screws placed in the sagittal plane (24% vs. 2%). Quadricortical facet screw placement aimed at the juncture between the transverse process and the facet is practicable. Screw loosening was significantly reduced using this lateral screw direction. One of the disadvantages of this technique is that extensive cranial exposure is required to align the instruments in the proper sagittal trajectory.