Underwent Pedicle Subtraction Osteotomy Research Articles

Clinical Outcomes and Complications after Pedicle Subtraction Osteotomy for Fixed Sagittal Imbalance Patients : A Long-Term Follow-Up Data

Clinical, radiographic, and outcomes assessments, focusing on complications, were performed in patients who underwent pedicle subtraction osteotomy (PSO) to assess correction effectiveness, fusion stability, procedural safety, neurological outcomes, complication rates, and overall patient outcomes. We analyzed data obtained from 13 consecutive PSO-treated patients presenting with fixed sagittal imbalances from 1999 to 2006. A single spine surgeon performed all operations. The median follow-up period was 73 months (range 41-114 months). Events during perioperative course and complications were closely monitored and carefully reviewed. Radiographs were obtained and measurements were done before surgery, immediately after surgery, and at the most recent follow-up examinations. Clinical outcomes were assessed using the Oswestry Disability Index and subjective satisfaction evaluation. Following surgery, lumbar lordosis increased from -14.1 degrees +/- 20.5 degrees to -46.3 degrees +/- 12.8 degrees (p < 0.0001), and the C7 plumb line improved from 115 +/- 43 mm to 32 +/- 38 mm (p < 0.0001). There were 16 surgery-related complications in 8 patients; 3 intraoperative, 3 perioperative, and 10 late-onset postoperative. The prevalence of proximal junctional kyphosis (PJK) was 23% (3 of 13 patients). However, clinical outcomes were not adversely affected by PJK. Intraoperative blood loss averaged 2,984 mL. The C7 plumb line values and postoperative complications were closely correlated with clinical results. Intraoperative or postoperative complications are relatively common following PSO. Most late-onset complications in PSO patients were related to PJK and instrumentation failure. Correcting the C7 plumb line value with minimal operative complications seemed to lead to better clinical results.

Early Union of Grafted Bone in Ankylosing Spondylitis: Comparative Study with Degenerative Spinal Disease

BackgroundPatients with ankylosing spondylitis (AS) achieve early bone union compared to those with other spinal diseases. This study compared the time to bone union after surgery between AS patients and degenerative spinal disease patients.MethodsPatients with degenerative spinal diseases (control group) and AS (experimental group) underwent pedicle subtraction osteotomy followed by posterolateral fusion, and decompression and posterolateral fusion, respectively. There were 10 patients in the experimental group. The control group included 26 patients who were less than 50 years of age and underwent two-level autogenous grafting after decompression and spinal fusion. Autogenous grafts and a range of bone substitutes were used in the experimental group, whereas only autogenous grafts were used in the control group. Bone union was determined on the radiographs and 3-dimensional CT scan images. The level of union was assessed using the Lenke's and Christensen's classification systems.ResultsIn the experimental group, the mean age was 41.3 years (range, 30 to 67 years), the mean follow-up period was 21.7 months (range, 12 to 43 months), and bone union was confirmed at an average of 3.5 months (range, 3 to 5 months) after surgery. In the control group, the mean age was 43.1 years (range, 35 to 50 years), the mean follow-up period was 21.8 months (range, 12 to 74 months), and bone union was observed at an average of 5.6 months (range, 4 to 12 months) after surgery. The difference in the time to bone union between the two groups was significant (p = 0.023).ConclusionsThe union of grafted bone was obtained earlier in patients with AS than in those with degenerative spinal diseases. Therefore, future studies should examine the factors affecting the early union in AS patients.

Radiological analysis of ankylosing spondylitis patients with severe kyphosis before and after pedicle subtraction osteotomy

This is a radiographic study of ankylosing spondylitis patients with severe fixed kyphotic deformity who underwent pedicle subtraction osteotomy. Our goal was to measure and validate new angle to assess global kyphosis and to evaluate the radiological outcomes after surgery. This is the first report which describes new angle to assess global kyphosis (T1-S1). Pre and postoperative controls were compared according to the Pelvic Incidence. The sagittal parameters ankylosing spondylitis patients were compared with 154 asymptomatic patients. In addition to the pelvic parameters and the C7 tilt, we used the spino-sacral angle. Pelvic incidence in ankylosing spondylitis patients was higher than asymptomatic population (61 vs. 51 degrees). For a same tilt of C7 for both groups, the low pelvic incidence group had a lower sacral slope and pelvic tilt and a higher global kyphosis (spino-sacral angle = 90 degrees) than the high pelvic incidence group (spino-sacral angle = 98 degrees ). In the adult volunteers, the C7 tilt and spino-sacral angle measured, respectively, 95 and 135 degrees. The preoperative C7 tilt measured 73 degrees and increased to 83 degrees (p = 0.0025). The preoperative spino-sacral angle measured 96 degrees and increased to 113.3 degrees (p = 0.003). A low pelvic incidence pelvis has a lower sacral slope than in high pelvic incidence and can support a bigger kyphosis. All the parameters were improved by the pedicle subtraction osteotomy, but the average spino-sacral angle remained lower than the control group. When C7 tilt was useful to assess the improvement of the balance, SSA allowed a better evaluation of the correction of kyphosis itself.

A novel mathematical model of the sagittal spine: application to pedicle subtraction osteotomy for correction of fixed sagittal deformity

Background context The C7 plumb line method oversimplifies the true complexity of the spine. In a previous study, we mathematically modeled the normal spine using the spline function, enabling quantification of previously undescribed measurements such as area under the curve (AUC) and average sagittal position. The spine in fixed sagittal imbalance and the results of surgical correction have not been studied in a similar manner. Purpose To quantitatively evaluate changes in spinal conformation in patients who underwent pedicle subtraction osteotomy (PSO) using measures derived from the spline model and to correlate these changes with functional outcome. Study design Application of a mathematical model to a cohort of patients who underwent deformity surgery. Patient sample Thirty-four consecutive patients with fixed sagittal imbalance who underwent PSO from 2001 to 2003. Outcome measures Preoperative and postoperative 22-item Scoliosis Research Society (SRS-22) Outcomes Questionnaire scores were used for functional assessment. Methods Radiographs of the 34 patients who underwent thoracic or lumbar PSO with at least 2 years of follow-up were examined at three time points. The posterosuperior aspect of each vertebral body was chosen as a representative point for the spinal sagittal curve. A cubic spline function was derived from these points. From this function, the AUCs and average sagittal positions of the thoracic, lumbar, and thoracolumbar segments were calculated. Results The average sagittal position does not overlap the C7 plumb line in deformity patients, but is a much more stable measure. In the lumbar PSO cohort, the lumbar AUC and average sagittal position were not significantly different among normal, preoperative, and postoperative groups. The thoracic and thoracolumbar AUCs and average sagittal positions were dramatically more positive in the preoperative cohort compared with normals; these values significantly decreased toward neutrality after lumbar PSO, but remained abnormal. In the thoracic PSO cohort, the lumbar, thoracic, and thoracolumbar AUCs and average sagittal positions were not significantly different among normal, preoperative, and postoperative groups. The changes in thoracolumbar AUC and average sagittal position were better predictors of the SRS-22 total score than the change in C7 plumb line. Conclusions The average sagittal position more comprehensively captures the nuances of a nonlinear spinal curve. Subcurve analysis enabled by the spline model is particularly helpful in assessing deformity and surgical correction on a segmental level. Increased sensitivity to the nuances of the spinal curve in this model results in superior correlation with clinical outcomes when compared with the C7 plumb line. We feel that a critical examination of the spinal curve will lead to improved understanding of deformity and planning for an optimal correction.

Clinical and radiographic outcomes of thoracic and lumbar pedicle subtraction osteotomy for fixed sagittal imbalance

The authors conducted a study to evaluate the radiographically documented and functional outcomes obtained in patients who underwent pedicle subtraction osteotomy (PSO). They also compared outcomes after classification of cases into thoracic and lumbar PSO subgroups. The authors analyzed data obtained in 35 consecutive PSO-treated patients with sagittal imbalance. One surgeon performed all surgeries. The minimal follow-up period was 2 years. Events during the perioperative course and complications were noted. Standing long-film radiographs of the spine were obtained and measurements were made preoperatively, immediately postoperatively, and at most recent follow-up examination. The modified Prolo Scale and the 22-item Scoliosis Research Society (SRS-22) Outcomes Questionnaire were administered. Early complications after PSO included neurological injury, wound-related problems, and nosocomial infections. Late complications were limited to pseudarthrosis and attendant instrumentation failure. Early and late complication rates ranged from 10 to 30% for both thoracic and lumbar PSO cohorts. Lumbar PSO was associated with improvements in local, segmental, and global measures of sagittal balance, whereas thoracic PSO was only associated with local improvement. Most patients rated their functional status as fair to good according to the modified Prolo Scale and reported, according to the SRS-22 Outcomes Questionnaire, that they were satisfied with the overall treatment of their back condition. The ability to perform a PSO at both lumbar and thoracic levels is a powerful asset for the spine surgeon treating spinal deformity. In the present study radiographic and clinical outcomes were superior when PSO was used to treat lumbar deformity rather than thoracic deformity because of several anatomical and technical obstacles that hindered the thoracic procedure. Nevertheless, the thoracic PSO proved a useful addition with which to produce regional improvement in sagittal balance for patients with a fixed thoracic kyphosis.

Ostéotomie de soustraction pédiculaire dans le traitement des déséquilibres antérieurs du rachis: À propos de 34 cas

Purpose of the study The aim of this study was to analyze x-ray results in patients who underwent pedicle subtraction osteotomy for complex deformations (flat back, kyphosis) leading to fixed sagittal imbalance. Material and methods Thirty-four patients underwent surgery between 1996 and March 2003 in two centers, the orthopedic surgery unit devoted to spinal surgery and sports traumatology at the Strasbourg University Hospitals and the spinal surgery unit at the Chenove Clinic (Dijon). The series included 20 women and 14 men, mean age 46.5 years (range 14-74 years) treated for: postoperative flat back (n = 19), kyphoscoliosis (n = 6), ankylosing spondylarthritis (n = 5), and malunion (n = 4). After careful planning to achieve the necessary degree of correction, the patient was installed on a Cotrel table with a stable support enabling limited blood loss and facilitated reduction maneuvers via elevation of the lower limbs. The technique started by resection of the posterior arch, the transverse processes, and the pedicles, followed by partial resection of the body with a chisel under fluoroscopic control. The closure was achieved by in situ reduction with compressive rotation. Adjacent discs were then evaluated to search for any opening which could be filled by an anterior graft to complete the stabilization. The osteosynthesis used 2-, 4-, and 6-rod assemblies. The 6-rod assemblies enabled anchoring the fixation above and below before the osteo-tomy. Two prebent rods completed the assembly at reduction after osteotomy. Weight-bearing started on day 4. A protective corset was worn for three months by 19 patients. The patients resumed their occupational activities on average 6.73 months postoperatively without change in activity for 63%. Overall satisfaction was close to 90% excellent outcome. Results All clinical results were analyzed with the Profil software of Surgiview. X-ray data were analyzed with Spineview. A self-administered clinical questionnaire was used to evaluate pain, result of the operation, and the impact on the patient's body image. On average, the wedge osteotomy measured 28.9° for correction of lumbar lordosis by 31.5̊ with a maximum of 65̊. The misalignment at C7 was reduced from 51 mm to 2 mm. At the pelvic level, version improved 16̊, sacral slope 8̊. There were four dura mater breaches which had to be sutured, but with no clinical consequence (one progression to meningocele). Mean intraoperative blood loss was 1400 cc (300-4500cc) for a mean operative time of 260 minutes (165-450 min). There were two early infections at day 15 postop which resolved with antibiotics. Four patients developed resolutive sciatica (n = 2) or cruralgia (n = 2) during the following months. The short-term follow-up revealed eight non-unions (25%) with rupture of osteosynthesis material and loss of correction. The opening in the adjacent discs and the insufficient posterior closure explained this mechanical complication. Conclusion Pedicle subtraction osteotomy is an original operative technique reserved for specialized centers. A well-experienced team is needed to control the risks involved. Sagittal balance should be one of the important goals for modern spinal surgery.

Comparison of Smith-Petersen Versus Pedicle Subtraction Osteotomy for the Correction of Fixed Sagittal Imbalance

Clinical, radiographic, and outcomes assessment comparing two surgical techniques. Clinical data were collected prospectively. The radiographic analysis was done retrospectively. Smith-Petersen (chevron type) osteotomy (SPO) and pedicle subtraction osteotomy (PSO) have been used to correct fixed sagittal imbalance. This study compares the results of these two methods. Our hypotheses were that when comparing three or more SPOs to a single PSO, the correction of kyphotic angle at the osteotomy site would be nearly identical in each group, the correction in C7 plumb and lumbar lordosis would be identical, the SPO group would have equal tendencies to decompensation as the PSO group, blood loss would be identical in the two groups, and improvement in Oswestry scores would be identical in each group. Many papers have described the surgical technique and results of SPOs and PSOs. No effort has been made to compare the results of the respective techniques at a single institution. Thirty patients who underwent SPO were compared with 41 patients who underwent PSO (follow-up, 2-11.5 years). All patients' surgeries were performed at one institution between 1989 and 2001. Fourteen patients in the SPO group had three or more osteotomies. All of the PSOs were performed at one segment. Patients were evaluated by preoperative and ultimate postoperative standing radiographs and a prospectively collected database with outcomes questionnaires. The mean correction of the kyphotic angle at the osteotomy sites for the SPOs was 10.7 degrees per segment. For those with three or more SPOs, the average total correction was 33.0 degrees +/- 9.2 degrees, and 31.7 degrees +/- 9.0 degrees for the PSO group. However, the improvement in sagittal balance was statistically significantly less with three or more SPOs (5.5 +/- 4.5 cm)than with one PSO (11.2 +/- 7.2 cm; P < 0.01). Comparing three or more SPOs to one PSO, the SPO group decompensated the patients more substantially to the concavity (P < 0.02). The mean estimated blood loss (adding up all anterior and posterior surgeries) for the procedure was 1,398 +/- 738 mL in the SPO group (1,392 +/- 664 mL in the three or more SPO group), and 2,617 +/- 1,645 mL in the PSO group (P < 0.001; P < 0.01). The mean Oswestry score improved from 42.3 +/- 14.2 before surgery to 21.3 +/- 14.8 at the last visit in the SPO group. In the PSO group, it improved from 47.9 +/- 15.8 before surgery to 29.7 +/- 18.3 at the last visit (P = 0.35). When comparing three or more SPOs (14 patients) to one pedicle subtraction procedure (41 patients), the correction in kyphosis was nearly identical. There was a significantly greater likelihood of decompensating the patient to the concavity with three or more SPOs than with a single PSO (P < 0.02). The blood loss was substantially greater with the PSO group (P < 0.001).

Lumbar pedicle subtraction osteotomy: clinical and radiographic

Anton A. Thompkins, MD, Courtney W. Brown, MD, David H. Donaldson, MD, John L. Brugman, MD, Douglas C. Wong, MD, James S. Gebhard, MD, Barbara J. Muff, RN, BSN, ONC, Golden, CO, USAIntroduction: Patients that have the diagnosis of “flat back syndrome” often have chronic debilitating back pain secondary to degenerative changes and global imbalance. The fixed sagittal imbalance places the spinal musculature at a mechanical disadvantage, increasing muscle fatigue, spasms and therefore pain. This difficult problem has been addressed in the past with either an anteroposterior spinal osteotomy and fusion or a Smith-Peterson osteotomy. By the very nature of these procedures, the spinal cord can be placed at risk secondary to the lengthening of the anterior spinal column. Pedicle subtraction osteotomy achieves a rebalanced spine without lengthening neural elements.Purpose: The purpose of this review is to report the clinical and radiographic outcome of patients who have undergone pedicle subtraction osteotomy in order to achieve significant correction of sagittal and coronal imbalance.Materials and methods: The clinical course and radiographic analysis of 27 consecutive patients who underwent pedicle subtraction osteotomy were evaluated. The clinical evaluation included operative time, blood loss, hospital stay, complications and the pre- and postoperative pain medication use. This information was gathered from both clinic and hospital charts and by direct contact with the patients. The radiographic analysis compared preoperative sagittal and coronal balance with postoperative sagittal and coronal balance. In addition, the amount of correction obtained at the osteotomy site and the overall lumbar sagittal contour change from pre- and postoperative radiographs were evaluated. The coronal balance was measured from C7 to the middle of the sacrum on an AP film with a plum line. The overall sagittal balance was measured from the anterior/inferior edge of C7 to the posterior aspect of S1 again, with a plum line. The osteotomy correction was measured using the Cobb angle technique from the end plate immediately above and below the operative level. The degree of lumbar lordosis was measured from the inferior end plate of T12 to the superior end plate of S1.Results: Sixteen female and 11 male patients underwent pedicle subtraction osteotomy between 1996 and 2000. The average age was 49 years, with the mean number of previous spinal operations of three. Even in the multiply operated spine, pedicle fixation was obtained 100% of the time in the lumbar spine to aid in maintaining the appropriated sagittal contour. The average blood loss was 1,116 cc and the average operative time was 6 hours and 45 minutes, with a mean hospital stay of 6 days. The average preoperative coronal and sagittal imbalance were 4.38 cm and 12.22 cm, respectively. The postoperative correction on the immediate follow-up showed coronal and sagittal balance of 1.84 cm and 3.42 cm, respectively. This represents a 58% correction in the coronal plane and a 72% correction in the sagittal plane. This correction was maintained at the latest follow-up with only a .09 cm average loss of correction in the coronal plane and .04 cm average loss of correction in the sagittal plane. This loss of correction is well within measurement error and is considered to be negligible. The average follow-up examination was 15 months from the index procedure. The correction obtained through the osteotomy site was 31 degrees on average with an increase in lumbar lordosis from 28 degrees preoperatively to 49 degrees postoperatively. The overall satisfaction with surgery was quite high, even with nine patients having complications. There were no incidences of spinal cord injury or nerve root loss. There were four infections (one deep, three superficial), which resolved with the appropriate antibiotic course. There were four cases of pseudarthrosis requiring a second operation, all of which went on to a solid union. In evaluating the amount of pain medicines used pre- and postoperatively, 60% of patients went from narcotic use to only an anti-inflammatory agent or nothing for pain management. Seventeen percent of the patients still used an occasional narcotic pain pill to manage their back pain, but all patients had an overall decrease in the use of pain medicines.Conclusion: Pedicle subtraction osteotomy is a safe and effect treatment for patients who have flat back syndrome. It is the authors' belief that pedicle subtraction osteotomy is a safer approach than the previously described methods of treating this problem. Pedicle subtraction osteotomy can be performed on patients who have had multiple spinal operations. This simple posterior procedure offers excellent radiographic and clinical improvements with limited complications.