Restricted cement augmentation in unstable geriatric midthoracic fractures treated by long-segmental posterior stabilization leads to a comparable construct stability

The goal of this study is to compare the construct stability of long segmental dorsal stabilization in unstable midthoracic osteoporotic fractures with complete pedicle screw cement augmentation (ComPSCA) versus restricted pedicle screw cement augmentation (ResPSCA) of the most cranial and caudal pedicle screws under cyclic loading. Twelve fresh frozen human cadaveric specimens (Th4–Th10) from individuals aged 65 years and older were tested in a biomechanical cadaver study. All specimens received a DEXA scan and computer tomography (CT) scan prior to testing. All specimens were matched into pairs. These pairs were randomized into the ComPSCA group and ResPSCA group. An unstable Th7 fracture was simulated. Periodic bending in flexion direction with a torque of 2.5 Nm and 25,000 cycles was applied. Markers were applied to the vertebral bodies to measure segmental movement. After testing, a CT scan of all specimens was performed. The mean age of the specimens was 87.8 years (range 74–101). The mean T-score was − 3.6 (range − 1.2 to − 5.3). Implant failure was visible in three specimens, two of the ComPSCA group and one of the ResPSCA group, affecting only one pedicle screw in each case. Slightly higher segmental movement could be evaluated in these three specimens. No further statistically significant differences were observed between the study groups. The construct stability under cyclic loading in flexion direction of long segmental posterior stabilization of an unstable osteoporotic midthoracic fracture using ResPSCA seems to be comparable to ComPSCA.

Application of an Expandable Cage for Reconstruction of the Cervical Spine in a Consecutive Series of Eighty-Six Patients

Background and objectives: Expandable cages are frequently used to reconstruct the anterior spinal column after a corpectomy. In this retrospective study, we evaluated the perioperative advantages and disadvantages of corpectomy reconstruction with an expandable cage. Materials and Methods: Eighty-six patients (45 male and 41 female patients, medium age of 61.3 years) were treated with an expandable titanium cage for a variety of indications from January 2012 to December 2019 and analyzed retrospectively. The mean follow-up was 30.7 months. Outcome was measured by clinical examination and visual analogue scale (VAS); myelopathy was classified according to the EMS (European Myelopathy Scale) and gait disturbances with the Nurick score. Radiographic analysis comprised measurement of fusion, subsidence and the C2–C7 angle. Results: Indications included spinal canal stenosis with myelopathy (46 or 53.5%), metastasis (24 or 27.9%), spondylodiscitis (12 or 14%), and fracture (4 or 4.6%). In 39 patients (45.3%), additional dorsal stabilization (360° fusion) was performed. In 13 patients, hardware failure occurred, and in 8 patients, adjacent segment disease occurred. Improvement of pain symptoms, myelopathy, and gait following surgery were statistically significant (p < 0.05), with a medium preoperative VAS of 8, a postoperative score of 3.2, and medium EMS scores of 11.3 preoperatively vs. 14.3 postoperatively. Radiographic analysis showed successful fusion in 74 patients (86%). As shown in previous studies, correction of the C2–C7 angle did not correlate with improvement of neurological symptoms. Conclusion: Our results show that expandable titanium cages are a safe and useful tool in anterior cervical corpectomies for providing adequate anterior column support and stability.

Accuracy of Placement of Pedicle Screws in the Lumbosacral Region of Dogs Using 3D-Printed Patient-Specific Drill Guides

Objective The aim of this study was to report the accuracy of pedicle screw placement using three-dimensional (3D)-printed, patient-specific drill guides in the lumbosacral region of dogs. Study Design This was a retrospective study. Thirty-two pedicle screws were placed in five dogs. Medical records were reviewed between November 2015 and November 2018 for dogs showing clinical signs associated with cauda equina syndrome. Inclusion criteria included preoperative magnetic resonance imaging, pre- and postoperative computed tomography (CT) and dorsal stabilization, with pedicle screws placed using 3D-printed, patient-specific drill guides and polymethylmethacrylate. Screw placement was evaluated for medial or lateral breaching on postoperative CT. Results Five dogs met the inclusion criteria. Four had degenerative lumbosacral stenosis and one had discospondylitis. All dogs had failed medical management prior to surgery. Of 32 bicortical pedicle screws placed, 30 were fully contained inside the pedicle and 2 were partially breaching the vertebral canal (less than one-third of the screw diameter). Postoperative CT revealed good alignment of L7-S1 in all planes. Conclusions This technique enabled an accurate and safe placement of pedicle screws in the lumbosacral region of dogs with lumbosacral disease. Three-dimensional, printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with lumbosacral disease.