Universal non-circular cone beam CT orbits for metal artifact reduction imaging during image-guided procedures.

Innovation in image-guided procedures has been driven by advances in robotic Cone Beam Computed Tomography (CBCT) systems. A fundamental challenge for CBCT imaging is metal artifacts arising from surgical tools and implanted hardware. Here, we outline how two universal non-circular imaging orbits, optimized for metal artifact reduction, can be implemented in real-time on clinical robotic CBCT systems.

Iron-induced Hypophosphatemic Osteomalacia-An Atypical Case of Bilateral Femoral Stress Fractures.

We present a case of a 61-year-old healthy man who had bilateral femoral neck insufficiency fractures attributed to repeated iron transfusions, causing iron-induced hypophosphatemic rickets, requiring surgical intervention. Atraumatic insufficiency fractures present a diagnostic dilemma in orthopaedics. Chronic fractures with no acute precipitating trigger can often go unrecognized until complete fracturing or displacement occurs.

Biomechanical Comparison of Subsidence Between Patient-Specific and Non-Patient-Specific Lumbar Interbody Fusion Cages.

Study Design: Biomechanical study.

Objectives: Several strategies to improve the surface of contact between an interbody device and the endplate have been employed to attenuate the risk of cage subsidence. 3D-printed patient-specific cages have been presented as a promising alternative to help mitigate that risk, but there is a lack of biomechanical evidence supporting their use.

Rates, Predictive Factors, and Adverse Outcomes of Fusion Surgery for Lumbar Degenerative Disorders in Ontario, Canada, Between 2006 and 2015: A Retrospective Cohort Study.

Background: The addition of fusion surgery to the decompression for lumbar degenerative disorders remains controversial. The purpose of this study is to compare the rate and outcome of decompression and fusion versus decompression alone.

Methods: This population-based retrospective cohort study used several linked administrative databases to identify patients who underwent spinal decompression surgery in Ontario, Canada, from 2006 to 2015.

Evaluation of the contact surface between vertebral endplate and 3D printed patient-specific cage vs commercial cage.

Biomechanical study. To evaluate the performance of the contact surface for 3D printed patient-specific cages using CT-scan 3D endplate reconstructions in comparison to the contact surface of commercial cages. Previous strategies to improve the surface of contact between the device and the endplate have been employed to attenuate the risk of cage subsidence.

Extended Intraoperative Longitudinal 3-Dimensional Cone Beam Computed Tomography Imaging With a Continuous Multi-Turn Reverse Helical Scan.

Objectives: Cone beam computed tomography (CBCT) imaging is becoming an indispensable intraoperative tool; however, the current field of view prevents visualization of long anatomical sites, limiting clinical utility. Here, we demonstrate the longitudinal extension of the intraoperative CBCT field of view using a multi-turn reverse helical scan and assess potential clinical utility in interventional procedures.

Materials And Methods: A fixed-room robotic CBCT imaging system, with additional real-time control, was used to implement a multi-turn reverse helical scan.

Generating patient-matched 3D-printed pedicle screw and laminectomy drill guides from Cone Beam CT images: Studies in ovine and porcine cadavers.

Background: The emergence of robotic Cone Beam Computed Tomography (CBCT) imaging systems in trauma departments has enabled 3D anatomical assessment of musculoskeletal injuries, supplementing conventional 2D fluoroscopic imaging for examination, diagnosis, and treatment planning. To date, the primary focus has been on trauma sites in the extremities.

Purpose: To determine if CBCT images can be used during the treatment planning process in spinal instrumentation and laminectomy procedures, allowing accurate 3D-printed pedicle screw and laminectomy drill guides to be generated for the cervical and thoracic spine.

Accuracy of Patient-Specific Drill Guide Template for Bilateral C1-C2 Laminar Screw Placement: A Cadaveric Study.

Objective: We sought to evaluate the accuracy of using patient-specific drill guides to place bilateral laminar screws in C1 and C2.

Methods: Nine cervical specimens (8 males; mean age: 66.6 [56-73]) with the occiput attached (C0-C3) were used in this study.

Early Versus Delayed Microdiscectomy for Chronic Sciatica Lasting 4-12 Months Secondary to Lumbar Disc Herniation: A Secondary Analysis of a Randomized Controlled Trial.

Objectives: To compare the effect of delaying surgery on clinical outcome in patients with chronic sciatica secondary to lumbar disc herniation.

Methods: Patients with sciatica lasting 4-12 months and lumbar disc herniation at the L4-L5 or L5-S1 level were randomized to undergo microdiscectomy (early surgery) or to receive 6 months of nonoperative treatment followed by surgery if needed (delayed surgery). Outcomes were leg pain, Oswestry Disability Index score (ODI), back pain, SF-36 physical component (PCS) and mental component (MCS) summary scores, employment, and satisfaction measured preoperatively and at 6 weeks, 3 months, 6 months, and 1 year after surgery.

Discectomy Compared with Standardized Nonoperative Care for Chronic Sciatica Due to a Lumbar Disc Herniation: A Secondary Analysis of a Randomized Controlled Trial with 2-Year Follow-up.

Background: Randomized controlled trials evaluating acute sciatica have not demonstrated prolonged improvements in terms of patient-reported pain and function. For chronic sciatica, however, microdiscectomy has been found to be superior at 1 year. Whether this effect persists during the second year is not known.

3D printed composite model of pelvic osteochondroma and nerve roots.

Background: 3D-printing has become increasingly utilized in the preoperative planning of clinical orthopaedics. Surgical treatment of bone tumours within the pelvis is challenging due to the complex 3D bone structure geometry, as well as the proximity of vital structures. We present a unique case where a composite bone and nerve model of the lower lumbar spine, pelvis and accompanying nerve roots was created using 3D-printing.

Biomechanical comparison of 3 types of transdiscal fixation implants for fixing high-grade L5/S1 spine spondylolisthesis.

Background Context: There are several options for the stabilization of high-grade lumbosacral spondylolisthesis including transdiscal screws, the Bohlman technique (transdiscal fibular strut) and the modified Bohlman technique (transdiscal titanium mesh cage). The choice of an optimum construct remains controversial; therefore, we endeavoured to study and compare the biomechanical performance of these 3 techniques.

Purpose: The aim of this study was to compare 3 types of transdiscal fixation biomechanically in an in vitro porcine lumbar-sacral spine model.

The Development of Novel 2-in-1 Patient-Specific, 3D-Printed Laminectomy Guides with Integrated Pedicle Screw Drill Guides.

Objective: To determine if 2-in-1 patient-specific laminectomy and drill guides can be safely used to perform laminectomy and pedicle screw insertion.

Methods: This was a cadaveric study designed to test novel 2-in-1 patient-specific laminectomy guides, with modular removable pedicle screw drill guides. Three-dimensional (3D) printing has not been applied to laminectomy.

Geometric and volumetric relationship between human lumbar vertebrae and "Black-bone" MRI-based models.

Background: This study will examine the differences between human lumbar vertebrae, three-dimensional (3D) scans of these bones, 3D models based on 'Black-bone' magnetic resonance imaging (MRI) scans, and 3D-printed models.

Materials And Methods: 3D mesh models were created from the "Black-bone" MRI data from two cadaveric human spines, and then 3D printed. Four models were analysed and compared: anatomic bones, 3D-scanned models, MRI models and 3D-printed models.

Anatomical relationship between the accessory process of the lumbar spine and the pedicle screw entry point.

Introduction: The vertebra accessory process (or tubercle) of the lumbar spine is an understated landmark which lies caudal to the mammillary process at the base of the transverse process. To our knowledge, no studies compare its relation to pedicle entry point for screw placement. We proposed to evaluate whether a valid and reliable relationship exists between the accessory process and the projected pedicle axis.

Geometric and Volumetric Relationship Between Human Lumbar Vertebra and CT-based Models.

Rationale And Objectives: Crucial to the process of three-dimensional (3D) printing is the knowledge of how the actual structure or organ relates dimensionally to its corresponding medical image. This study will examine the differences between human lumbar vertebrae, 3D scans of these bones, 3D models based on computed tomographic (CT) scans, and 3D-printed models.

Materials And Methods: CT scans were obtained for six human lumbar spines.

The change in position of the axillary nerve with rotation of the arm.

The axillary nerve is the most commonly injured nerve around the arm. In the deltopectoral approach, classical teaching states that lateral rotation of the humerus increases the distance between the subscapularis and the axillary nerve. This is the first anatomical study to quantify the distance change between the axillary nerve and subscapularis produced by arm rotation.

Extensile lateral versus sinus tarsi approach for displaced, intra-articular calcaneal fractures: a meta-analysis.

Background: Operative management of displaced, intra-articular calcaneal fractures is associated with improved functional outcomes but associated with frequent complications due to poor soft tissue healing. The use of a minimally invasive sinus tarsi approach to the fixation of these fractures may be associated with a lower rate of complications and therefore provide superior outcomes without the associated morbidity of operative intervention.

Methods: We reviewed four prospective and seven retrospective trials that compared the outcomes from the operative fixation of displaced intra-articular calcaneal fractures via either an extensile lateral approach or minimally invasive fixation via a sinus tarsi approach.

The distance of the femoral neurovascular bundle from the hip joint: an intraoperative guide to reduce iatrogenic injury.

Background: Iatrogenic injury to the femoral neurovascular bundle is not uncommon during primary and revision total hip replacement (THR) and can result in permanent weakness, pain and poor function. Prevention of injury to these structures relies on a sound knowledge of their relationships to the hip joint.

Methods: We studied 115 consecutive hip magnetic resonance imaging (MRI) results in order to identify objective relationships between these structures and the hip joint that can be used intraoperatively.

Position of the sciatic nerve and effect of gluteus maximus release during hip arthroplasty.

Eight Thiel embalmed hips were dissected. The distance between the sciatic nerve and the femoral neck was measured before and after hip dislocation, and before and after release of the gluteus maximus tendon. There was a significant reduction in the mean distance between the neck of femur and the sciatic nerve in both the gluteus maximus tendon release and the unreleased groups at 60° and 90° of hip flexion, p < 0.

The Distance of the Common Peroneal Nerve to the Posterolateral Structures of the Knee.

Background: The common peroneal nerve (CPN) is an important structure of the lower limb and is at risk of injury during total knee arthroplasty. The aim of this study was to use a tibial reference system to determine the position of the CPN relative to the knee center and popliteus.

Methods: Two hundred consecutive knee magnetic resonance images at the level of a standard tibial arthroplasty cut were evaluated for (1) distance of the CPN from the posterolateral capsule; (2) angle of the CPN from the center of the tibial anteroposterior axis; and (3) location of CPN with respect to the popliteus.

Safe zone for the superficial femoral artery demonstrated on computed tomography angiography.

Introduction: Internal or external fixation of the femur is common following trauma. Neurovascular structures around the shaft of the femur are at risk, particularly the superficial femoral artery (SFA). Damage to this structure, when it is medial to the femur, can occur during the lateral approach, when drills, pins or screws are inserted.