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Study design This was a retrospective clinical review. Objective The objective of this study was to analyze failure mechanisms after total lumbar disk replacement (TDR) and surgical revision strategies in patients with recurrent low back pain (LBP). Summary and background data Several reports indicate that TDR revision surgery carries a major risk and that it should not be recommended. The clinical results of posterior instrumented fusion using the prosthesis like an interbody cage have not been well analyzed. Materials and methods From 2003 to 2018, 48 patients with recurrent LBP after TDR underwent revision surgery. The average age was 39 years (24-61 y). The mean follow-up was 100.4 months (24.6-207.7 mo). Clinical data, self-assessment of patient satisfaction, and Oswestry Disability Index collected at each clinical control or by phone call for the older files and radiologic assessments were reviewed. The surgical revision strategy included posterior fusion in 41 patients (group A) and TDR removal and anterior fusion in 7 patients (group B), of which 6 patients had an additional posterior fixation. Results Facet joint osteoarthritis was associated with TDR failure in 85%. In 68% the position of the prosthesis was suboptimal. Range of motion was preserved in 25%, limited in extension in 65%, and limited in flexion in 40%. Limited range of motion and facet joint osteoarthritis were significantly related (P=0.0008). The complication rate in group B was 43% including iliac vein laceration. Preoperative and 2-year follow-up Oswestry Disability Index were 25.5 and 22.0, respectively, in group A versus 27.9 and 21.3 in group B. Conclusions Posterior osteoarthritis was the principal cause of recurrent LBP in failed TDR. The anterior approach for revision carried a major vascular risk, whereas a simple posterior instrumented fusion leads to the same clinical results. Level of evidence Level IV.

The two-dimensional fluoroscopic method of percutaneous pedicle screw instrumentation has been clinically described as reliable method in the caudal thoracic and lumbosacral spine. Its accuracy has not been clearly reported in the cranial thoracic spine. The aim of this in vitro study was to investigate percutaneous pedicle screw placement accuracy according to pedicle dimensions and vertebral levels. Six fresh-frozen human specimens were instrumented with 216 screws from T1 to S1. Pedicle isthmus widths, heights, transversal pedicles and screws were measured on computed tomography. Pedicle cortex violation ≥ 2 mm was defined as screw malposition. The narrowest pedicles were at T3–T5. A large variability between transversal pedicle axes and percutaneous pedicle screw was present, depending on the spinal level. Screw malposition rates were 36.1% in the cranial thoracic spine (T1–T6), 16.7% in the caudal thoracic spine (T7–T12), and 6.9% in the lumbosacral spine (L1–S1). The risk for screw malposition was significantly higher at cranial thoracic levels compared to caudal thoracic (p = 0.006) and lumbosacral (p

Introduction Simulation workshops for surgical training of residents are becoming popular. The gold standard for teaching thoracolumbar pedicle screw placement are cadaver labs; however, the availability of human bodies is limited. The primary objective of this study was to determine if training on a synthetic bone model improves the apprenticeship of accurate pedicle screw placement. The secondary objective was to check the influence of residents’ previous experience in spine surgery. Hypothesis The main hypothesis was that theoretical learning with practical application on synthetic bone was superior to theoretical learning alone. Methods Twenty-three orthopedic residents were taught about free-hand pedicle screw placement using a theoretical presentation. Six residents had previous experience with screwing techniques. After randomization in two groups, 11 residents (group 1) participated in a workshop on synthetic bone, whereas 12 residents received only theoretical instruction (group 2). Each resident was asked to place two thoracic screws (T7-T11) and two lumbar screws (L1-L5) on a cadaver. Screw placement accuracy was analyzed using the Gertzbein classification on computed tomography (grades 0 and 1 = accurate positioning; grades 2 and 3 = malposition > 2 mm). Results Rates of accurate screw positioning were 64.0% and 62.5% for thoracic levels, and 72.7% and 66.6% for lumbar levels in group 1 and 2, respectively. There was no significant difference in malposition rates on cadavers between the groups (p = 0.1809). A resident who was first trained by simulation had a chance of decreasing the Gertzbein score with an odds-ratio of 1.7714 [0.7710–4.1515]. The odds ratio was 4.5188 [0.0456–0.8451] when comparing residents with previous experience in spinal surgery to novice residents. Discussion Theoretical teaching associated with a simulation model is relevant for learning a surgical technique. A single simulation workshop on synthetic bone seems insufficient to improve pedicle screw placement accuracy compared to theoretical teaching alone. Progressive experience and the repetition of technical gestures during hands-on supervised learning in spine surgery with a senior surgeon had an influence on the accuracy of pedicle screw placement. Level of evidence II.

A long global thoracolumbar kyphosis is common in ankylosing spondylitis. Surgical correction of fixed sagittal malalignment by pedicle subtraction osteotomy (PSO) might improve disability and quality of life (QoL). Two-level osteotomies represent major procedures with a risk of hemorrhage. Combined open and minimal invasive surgery has not been described and might be considered. A 30-year-old female with ankylosing spondylitis was treated by golimumab and teriparatide. The treatment was stopped during pregnancy which led to vertebral compression fractures and kyphosis of 50° between T11 and L3. A PSO was planned at the kyphotic apex L2. The second PSO was planned at L4 according to the pelvic incidence of 56°, matching with a spinopelvic alignment Roussouly type 3. A derived full balance integrated method was used to calculate the amount of correction. During the first stage surgery, an open approach was performed from L1 to pelvis and combined with percutaneous cement-augmented instrumentation in already fused segments T5–T12, thus reducing perioperative morbidity. A stepwise approach including L2 PSO closure with temporary rods and L4 PSO with final instrumentation was used. Blood loss was estimated around 1100 ml. The patient was able to walk on the second day after surgery. A secondary anterior fusion with LLI cages from L2 to L5 and an ALIF at L5–S1 were performed because of high non-ossified intervertebral disks to reduce the risk for nonunion and rod fractures. At 2-year follow-up, the patient’s QoL had significantly improved and full spine radiographs showed stable normalized sagittal parameters. The combined open and percutaneous approach was feasible and might be considered as an alternative option to conventional open surgery when planning major deformity correction in ankylosing spondylitis.

Percutaneous instrumentation and kyphoplasty can be used to treat A3 fractures at T12-L1. However, the effect on adjacent intervertebral discs remains controversial. The purpose of this retrospective study was to analyze the degeneration of the discs adjacent to the fracture and to determine its relationship with age, vertebral body deformity and clinical scores.Twenty-nine patients (11 females, 18 males; average age 47 years, 27-63 years) were examined at 2.2 years' follow-up (2.0-2.5). Radiographic measurements were taken preoperatively, postoperatively, at follow-up: regional and local kyphosis, sagittal index, vertebral body compression ratio, and disc height index. The Pfirrmann grade was determined on an MRI taken at the final assessment. Clinical scores were the pain level (VAS), EQ-5D-3L, and ODI. The relationships between Pfirrmann grades, age and radiographic parameters were analyzed.Local kyphosis decreased from 12.4° to 7.3° postoperatively (p0.0001), increased to 8.4° after instrumentation removal (p=0.139) and remained stable at the last follow-up (p=0.891). The sagittal index decreased from 12.3° to 7.3° postoperatively (p0.0001) increased to 8.3° before the instrumentation was removed (p=0.764) and increased to 10.6° (p0.05) at the last follow-up. The vertebral body compression ratio decreased from 23% to 14% postoperatively (p0.0001) and remained stable at 17% at the last follow-up (p=0.310). The cranial disc height index was 32% preoperatively, 31% postoperatively (p=0.073), 29% at 1year (p=0.650), and decreased again to 23% at 2 years (p0.0001). There was a significant relationship between disc degeneration and age (p=0.015), local kyphosis (p=0.008) and vertebral body compression ratio (p=0.002). The disc adjacent to the fracture was more likely to have a higher Pfirrmann grade than the control disc above it (OR=269.5). At the final assessment, the average pain level was 2.3, the EQ-5D-3L was 0.862, and the ODI was 11.8%. There was no significant relationship between the Pfirrmann grades and the clinical scores.The risk for cranial disc degeneration after percutaneous instrumentation and kyphoplasty of A3 fractures is low. The height of the cranial disc decreased after the instrumentation was removed. The risk for disc degeneration is related to age and vertebral body deformity. Disc degeneration does not appear to impact quality of life.