Lumbar pedicle subtraction osteotomy
Pedicle subtraction osteotomy is a type of lumbar spine surgery.
see also Mini open pedicle subtraction osteotomy.
Indications
Lumbar pedicle subtraction osteotomy (PSO) is indicated in the treatment of large sagittal plane deformity (more than 25° of rigid loss of lordosis) of the lumbar spine or its combination with coronal deformity, especially when they are rigid. Indication should be based on careful assessment of the severity of symptoms, functional impairment, functional expectations of the patient, general clinical condition and surgical and anesthesiological team experience. Risk should be carefully assessed and discussed to obtain appropriate informed consent.
Surgical planning includes selection of the safest levels for the upper and lower instrumented vertebra, site of the osteotomy, modality of fixation, and, most importantly angular value of the correction goal (target lumbar lordosis). Failure to adequately obtain the necessary amount of sagittal correction is the most frequent cause of failure and reoperation.
PSO is a valuable surgical procedure in correction of severe hypolordosis (=relative kyphosis) in the lumbar spine. It is a demanding procedure for the surgeon, the anesthesiologist and the intensive care team. Although its complication rate is high, it has a substantial positive impact in the quality of life of patients, including the elderly 1).
Smith Petersen osteotomy (SPOs) yield approximately 10° of lordosis per level, whereas pedicle subtraction osteotomy result in as much as 30° increased lumbar lordosis.
Selective release of the anterior longitudinal ligament (ALL) and placement of lordotic interbody grafts using the minimally invasive lateral retroperitoneal transpsoas approach (XLIF) has been performed as an attempt to increase lumbar lordosis while avoiding the morbidity of osteotomy.
Videos
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Pedicle Substraction Osteotomy was demonstrated by Christopher Shaffery, M.D. at the Seattle Science Foundation for the 6th Annual One Spine Residents & Fellows Course.
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Case series
Retrospective comparative cohort study using the National Surgical Quality Improvement Program.
Objective: The aim of this study was to evaluate trends in the annual number of PSOs performed, describe the patient populations associated with each cohort, and compare outcomes between specialties.Summary of Background Data:Pedicle subtraction osteotomies (PSO) are complex and advanced spine deformity surgical procedures performed by neurosurgeons and orthopedic surgeons. Though both sets of surgeons can be equally qualified and credentialed to perform a PSO, it is possible that differences in training and exposure could translate into differences in patient management and outcomes.
Methods: Patients that underwent lumbar PSO from 2005 to 2014 in the American College of Surgeons-National Surgical Quality Improvement Program registry were identified. Relevant demographic, preoperative comorbidity, and postoperative 30-day complications were queried and analyzed. The data was divided into 2 cohorts consisting of those patients who were treated by neurosurgeons versus orthopedic surgeons. Additional data from the Scoliosis Research Society Morbidity and Mortality database was queried and analyzed for comparison.
Results: Demographic and comorbidity factors were similar between the neurosurgery and orthopedic surgery cohorts, except there were higher rates of hypertension among orthopedic surgeon-performed PSOs (65.66% vs. 48.67%, P =0.004). Except for 2012, in every year queried, orthopedic surgeons reported more PSOs than neurosurgeons. In patients who underwent lumbar fusion surgery, there was a higher rate of PSOs if the surgery was performed by an orthopedic surgeon (OR 1.7824, 95% CI: 1.4017-2.2665). The incidence of deep vein thrombosis after PSOs was higher for neurosurgery compared with orthopedic surgery (8.85% vs. 1.20%, P =0.004). However, besides deep vein thrombosis, there were no salient differences in surgical complication rates between neurosurgeon-performed PSOs and orthopedic surgeon-performed PSOs.
Conclusions: The number of PSO procedures performed by neurosurgeons and orthopedic surgeons has increased annually. Differences in outcomes between neurosurgeons and orthopedic surgeons suggest an opportunity for wider assessment and alignment of adult spinal deformity surgery exposure and training across specialties 2).
2008
A retrospective study of 10 patients (mean age, 56 yr; range, 7-77 yr) undergoing thoracolumbar PSO at a single institution in the past 3 years. Two patients underwent PSO at T12, seven patients underwent PSO at L3, and one patient underwent PSO at L2. Eight of the patients had undergone at least one previous spine surgery in the region of the PSO, and nine of the patients had comorbidities that increased their surgical risk stratification. We identified all causes of perioperative morbidity.
We classified perioperative complications into two categories: intraoperative and early postoperative. Intraoperative complications included dural tears in two patients, cardiovascular instability in one patient, and coagulopathy in two patients. Early postoperative complications included neurological deficit (one patient), wound infection (two patients), urinary tract infection (one patient), and delirium (two patients). All patients recovered fully from these complications. There was no mortality in this series.
In this series, most patients undergoing PSO had multiple previous spine surgeries and comorbidities. The risk of perioperative morbidity for revision cases undergoing PSO was in excess of 50%. We discuss complication-avoidance strategies 3).
Case reports
Pijpker et al., Department of Neurosurgery, Groningen, The Netherlands, present a case of severe congenital kyphoscoliosis in a young girl who suffers from skeletal dysplasia. A closing wedge extended Pedicle Subtraction Osteotomy was 3D virtual planned using medical computer design software. After the optimal 3D-wedge was planned, individualized osteotomy guiding templates were designed, for translation of the planned PSO towards the surgical procedure. During surgery the PSO was carried out by use of the osteotomy templates. A successful correction of the kyphoscoliosis was realized.
The kyphosis was successfully reduced using wedge shaped extended PSO, based on the pre-operative 3D virtual planning, assisted by 3D printed individualized osteotomy guiding templates. Besides direct translation of the planned PSO towards surgery, the 3D planning also facilitated detailed preoperative evaluation, more insight in the case-specific anatomy, and accurate planning of the required correction 4).