Jacob M. Buchowski

Adjacent segment disease followinglumbar/thoracolumbar fusion with pedicle screw instrumentation: a minimum 5-year follow-up.

Study Design. Retrospective radiographic outcomes analysis. Objective. We had 3 hypotheses: 1) a longer fusion; 2) a more proximal instrumented vertebra, and 3) circumferential fusion versus posterior-only fusion would increase the likelihood of adjacent segment disease (ASD). Summary of Background Data. The literature analyzing risk factors, prevalence, and presentation of patients with ASD is varied and without clear consensus. Methods. A total of 188 patients with minimum 5-year follow-up who had lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative disorders were included. Radiographic ASD was defined by: 1) development of spondylolisthesis >4 mm, 2) segmental kyphosis >10°, 3) complete collapse of disc space, or 4) more than 2 grades worsening of Weiner classification. Clinical ASD was defined as 1) symptomatic spinal stenosis, 2) intractable back pain, or 3) subsequent sagittal or coronal imbalance. Results. Radiographic ASD occurred in 42.6% (80 of 188) of patients. Patients with radiographic ASD had worse Oswestry scores (20.3 vs. 12.5; P = 0.001) at ultimate follow-up than those without ASD. Clinical ASD developed in 30.3% (57 of 188) of patients. Clinical ASD manifested as spinal stenosis (n = 47), instability-type back pain (n = 5), and sagittal or coronal imbalance (n = 5). Age at surgery over 50 years and length of fusion were significant risk factors for the development of ASD in the lumbar spine. Fusion to L1–L3 proximally increased the risk of ASD when compared with L4 and L5. Circumferential fusion versus posterior fusion was not a significant factor in the development of ASD. Conclusion. Patients over the age of 50 were at higher risk of developing clinical ASD than those 50 years old or younger. Length of fusion was a significant risk factor in the development of ASD in the lumbar spine. Fusion up to L1–L3 increased the risk of ASD when compared with L4 and L5. Circumferential fusion, as opposed to posterolateral fusion, was not a statistically significant risk factor for the development of ASD.

Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes.

Study Design. A meta-analysis of surgical outcomes of cauda equina syndrome secondary to lumbar disc herniation. Objectives. To determine the relationship between time to decompression after onset of cauda equina syndrome and clinical outcome, and to identify preoperative variables that were associated with outcomes. Summary of Background Data. The timing of surgical decompression for cauda equina syndrome is controversial. Although most surgeons recommend emergent decompression, results in certain studies show that delayed surgery may provide a satisfactory outcome. Methods. A meta-analysis was performed to determine the correlation between timing of decompression and clinical outcome. One hundred four citations were reviewed, and 42 met the inclusion criteria. Preoperative and postoperative data were recorded. Length of time to surgery was broken down into five groups: less than 24 hours, 24–48 hours, 2–10 days, 11 days to 1 month, and more than 1 month. Logistic regression was used to determine the association between preoperative variables and postoperative outcomes. Results. Outcomes were analyzed in 322 patients. Preoperative chronic back pain was associated with poorer outcomes in urinary and rectal function, and preoperative rectal dysfunction was associated with worsened outcome in urinary continence. In addition, increasing age was associated with poorer postoperative sexual function. No significant improvement in surgical outcome was identified with intervention less than 24 hours from the onset of cauda equina syndrome compared with patients treated within 24–48 hours. Similarly, no difference in outcome occurred in patients treated more than 48 hours after the onset of symptoms. Significant differences, however, were found in resolution of sensory and motor deficits as well as urinary and rectal function in patients treated within 48 hours compared with those treated more than 48 hours after onset of symptoms. Conclusions. There was a significant advantage to treating patients within 48 hours versus more than 48 hours after the onset of cauda equina syndrome. A significant improvement in sensory and motor deficits as well as urinary and rectal function occurred in patientswho underwent decompression within 48 hours versus after 48 hours.

Role of pelvic incidence, thoracic kyphosis, and patient factors on sagittal plane correction following pedicle subtraction osteotomy.

Study Design. An analysis of clinical and radiographic data of 40 consecutive patients with fixed sagittal imbalance. Objective. To determine the effect of mid lumbar pedicle subtraction osteotomy (PSO), pelvic incidence (PI), thoracic kyphosis (TK), and patient characteristics on correction obtained in patients with fixed sagittal imbalance. Summary of Background Data. PSO is commonly performed for spinal reconstruction in patients with fixed sagittal imbalance. Prior studies have not investigated the role that osteotomy location, PI, TK, and presenting patient characteristics may play in the correction obtained after PSO. Methods. Forty consecutive patients were identified who underwent PSO with minimum 2-year clinical and radiographic follow-up at a single institution. Data were analyzed before surgery and at 2 and 24 months after surgery to identify the magnitude and durability of correction and associated variables. Results. C7 plumb line improved from mean 15 cm anterior to the sacrum before surgery to 3.0 cm after surgery and 4.5 cm at 24 months (P < 0.0001); mean PSO wedge size was 32.4°. Patients treated for idiopathic deformity (typically following prior Harrington rod fusions) had better maintenance of correction than patients with degenerative sagittal imbalance, although not statistically significant (P = 0.06). Fusion to the upper thoracic spine preserved correction better than fusion to the thoracolumbar junction. Sagittal plane correction, SRS outcome scores and Oswestry scores were equivalent comparing PSOs performed at L2 and L3. Using our patient data, we tested models of PI and TK to predict the lumbar lordosis needed to achieve ideal sagittal balance. The formula PI + LL + TK ≤45° showed 91% sensitivity for predicting ideal sagittal balance at 24 months (P = 0.001). Conclusion. PI and TK can predict the lumbar lordosis necessary to correct sagittal imbalance in patients under-going PSO with high sensitivity. Sagittal correction and clinical outcome scores were equivalent comparing PSOs performed at L2 and L3. Patients with degenerative sagittal imbalance and those with shorter fusions are more likely to lose correction with time.

Neurologic complications of lumbar pedicle subtraction osteotomy: a 10-year assessment.

Study Design. Clinical, radiographic, and outcomes assessment focusing on neurologic complications in patients undergoing pedicle subtraction osteotomy (PSO). Clinical data were collected prospectively. Radiographic analysis was performed retrospectively. Objective. To evaluate intraoperative and postoperative neurologic deficits following lumbar PSOs in order to determine risk factors, treatment strategies, and patient outcome. Summary of Background Data. Although technically demanding, PSOs have been increasingly used to restore lumbar lordosis and correct sagittal deformity. Although some reports have commented on various complications of the procedure, to our knowledge, there have been no studies focusing on neurologic complications of the osteotomy. Methods. An analysis of 108 consecutive patients with an average age of 54.8 ± 14.0 years and treated with a lumbar PSO at 1 institution over a 10-year period (1995–2005) was performed. Medical records, radiographs, and neuromonitoring data were analyzed. Clinical outcome was assessed using the Oswestry Disability Index and the Scoliosis Research Society (SRS)-24 instruments. Results. A total of 108 PSOs were performed. Following surgery, lumbar lordosis increased from −17.1° ± 19.3° to −49.3° ± 14.7° (P < 0.000), and sagittal balance improved from 131 ± 73 mm to 23 ± 48 mm (P < 0.000). Intraoperative and postoperative deficits (defined as motor loss of 2 grades or more or loss of bowel/bladder control) were seen in 12 patients (11.1%) and were permanent in 3 patients (2.8%). With time motor function improved by 1 grade in 2 patients and all 3 were able to ambulate. Intraoperative neuromonitoring did not detect the deficits. In 9 patients, additional surgical intervention consisted of central enlargement and further decompression. Deficits were thought to be due to a combination of subluxation, residual dorsal impingement, and dural buckling. Conclusion. Intraoperative or postoperative neurologic deficits are relatively common following a PSO; however, in a majority of cases, deficits are not likely to be permanent.

Operative treatment of adolescent idiopathic scoliosis with posterior pedicle screw-only constructs: minimum three-year follow-up of one hundred fourteen cases.

Study Design. Preoperative review of a prospective study, single institution, consecutive series. Objective. To analyze the intermediate-term follow-up of consecutive adolescent idiopathic scoliosis (AIS) patients treated with pedicle screw constructs. Summary of Background Data. There have been no reports of the intermediate-term findings in North America following posterior spinal fusion with the use of pedicle screw-only constructs. Methods. One hundred and fourteen consecutive patients having a minimum 3-year follow-up (mean 4.8 ± 1.1; range, 3.0–7.3 years) with AIS were evaluated. The average age at surgery was 14.9 ± 2.2 years. Radiographic measurements included preoperative (Preop), postoperative (PO), 2-year (2 years), and final follow-up (FFU). A chart review evaluated PFTs, Scoliosis Research Society scores, presence of thoracoplasty, Risser sign, Lenke classification, and complications. Results. The most frequent curve pattern was Lenke type 1 (45.6%), followed by type 3 (21.9%). The average main thoracic curve measured 59.2° ± 12.2 SD Preop, and corrected to 16.8° ± 9.9 PO (P < 0.0001). Sagittal thoracic alignment (T5–T12) decreased from 25.8° to 15.5° at FFU (P = 0.05). Nash-Moe grading for apical vertebral rotation (AVR) in the proximal thoracic curve decreased from 2.0 Preop to 1.1 at FFU (P < 0.0001), and AVR in the thoracolumbar/lumbar spine decreased from 1.6 Preop to 1.1 at FFU (P < 0.0001). Importantly, the horizontalization of the subjacent disc measured −8.3° Preop which decreased to −0.9° PO (P < 0.001). PFT follow-up averaged 2.4 years with a 7.1% improvement in FVC (P = 0.004) and 8.8% in FEV1 (P < 0.0001). SRS scores averaged 83.0% at latest follow-up. Age, gender, Risser sign, or complications did not have a significant effect on outcomes. There were 2 cases of adding-on, 3 late onset infections, 1 with a single pseudarthrosis, but no neurologic complications. Conclusion. This is the largest (N = 114), consecutive series of North American patients with AIS treated with pedicle screws having a minimum of 3-year follow-up. The average curve correction was 68% for the main thoracic, 50% for the proximal thoracic, and 66% for the thoracolumbar/lumbar curve at final follow-up.

Major Complications and Comparison Between 3-column Osteotomy Techniques in 105 Consecutive Spinal Deformity Procedures

Study Design. A retrospective review. Objective. To characterize the risk factors for the development of major complications in 3-column osteotomies and determine whether the presence of a major complication affects ultimate clinical outcomes. Summary of Background Data. Three-column spinal osteotomies, including pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR), are common techniques to correct severe and/or rigid spinal deformities. Methods. Two hundred forty consecutive PSO (n = 156) and VCR (n = 84) procedures in 237 patients were performed at a single institution between 1995 and 2008. Of these, 105 patients (87 PSOs, 18 VCRs) had complete preoperative and minimum 2-year postoperative clinical outcomes data available for analysis. Using established criteria, we reported complications as major or minor and further stratified complications as surgical versus medical and permanent versus transient. Risk factors for complications and their effect on Scoliosis Research Society (SRS) clinical outcomes at baseline and at 2 years or more were assessed. Results. Major medical and surgical complications occurred at similar rates in both PSOs and VCRs (38%, 33 of 87 vs. 22%, 4 of 18; P = 0.28). Overall, 24.8% (26 of 105) experienced major surgical complications (3 permanent) and 15.2% (16 of 105) experienced major medical complications (4 permanent). Patients with PSO were older (53 vs. 29 yr; P < 0.001), had greater estimated blood loss (1867 vs. 1278 mL; P = 0.02), and showed a trend toward fewer fused levels (10.1 vs. 12.2; P = 0.06). Risk factors for major complications included preoperative sagittal imbalance of 40 mm or more (P = 0.01), age 60 years and older (P = 0.01), and the presence of 3 or more medical comorbidities (P = 0.04). Both groups improved significantly from baseline in SRS subscores; however, patients with PSO started off worse but improved more than VCRs in both the pain (+1.0 vs. +0.1; P < 0.001) and function (+0.6 vs. +0.2; P = 0.01) domains, with no differences in final satisfaction (4.1 vs. 4.3; P = 0.54). PSO and VCR patients with no complications had slightly higher satisfaction scores than patients with minor-only complications, major transient complications, and major permanent complications. There were no significant differences among the groups with respect to change in SRS subscores from baseline, and all complication groups improved significantly from baseline (P = 0.04). Conclusion. Major complications occurred in 35% of 3-column osteotomies and at similar rates for both PSO (38%) and VCR (22%) procedures. The presence of a major complication did not affect the ultimate clinical outcomes at 2 years or more.

Cervical Disc Arthroplasty Compared with Arthrodesis for the Treatment of Myelopathy

BACKGROUND Although there have been case reports describing the use of cervical disc arthroplasty for the treatment of myelopathy, there is a concern that motion preservation may maintain microtrauma to the spinal cord, negatively affecting the clinical results. As we are not aware of any studies on the use of arthroplasty in this scenario, we performed a cross-sectional analysis of two large, prospective, randomized multicenter trials to evaluate the efficacy of cervical disc arthroplasty for the treatment of myelopathy. METHODS The patients in the current study were a cohort of patients who were enrolled in the United States Food and Drug Administration Investigational Device Exemption studies of the Prestige ST and Bryan disc replacements (Medtronic, Memphis, Tennessee). The inclusion criteria were myelopathy and spondylosis or disc herniation at a single level from C3 to C7. Clinical outcome measures were collected preoperatively and at six weeks, three months, six months, twelve months, and twenty-four months postoperatively. RESULTS A total of 199 patients were included in the present study; 106 patients (53%) underwent arthroplasty, whereas ninety-three (47%) underwent arthrodesis. The Neck Disability Index, Short Form-36 scores, and specific arm and neck pain scores improved significantly from baseline at all time points. Patients in all four groups had improvement in the postoperative neurological status and gait function; at twenty-four months after surgery, 90% (95% confidence interval, 77.8% to 96.6%) of the patients in the arthroplasty group and 81% (95% confidence interval, 64.9% to 92.0%) of those in the arthrodesis group had improvement in or maintenance of the neurological status in the Prestige ST trial and 90% (95% confidence interval, 75.8% to 97.1%) of the patients in the arthroplasty group and 77% (95% confidence interval, 57.7% to 90.1%) of those in the arthrodesis group had improvement in or maintenance of the neurological status in the Bryan trial. CONCLUSIONS We found that patients in both the arthroplasty and arthrodesis groups had improvement following surgery; furthermore, improvement was similar between the groups, with no worsening of myelopathy in the arthroplasty group. While the findings at two years postoperatively suggest that arthroplasty is equivalent to arthrodesis for the treatment of cervical myelopathy for a single-level abnormality localized to the disc space, the present study did not evaluate the treatment of retrovertebral compression as occurs in association with ossification of the posterior longitudinal ligament, and we cannot comment upon the treatment of this condition.

Dural ectasia in the Marfan syndrome: MR and CT findings and criteria

Purpose: To create criteria for detecting dural ectasia on MR or CT images in adult Marfan patients.Methods: Images were analyzed using a workstation. Parameters that predicted dural ectasia were included in our criteria.Results: Major criteria include: (1) width of dural sac below L5 > width above L4; (2) anterior sacral meningocele. Minor criteria include: (1) L5 nerve root sleeve diameter > 6.5 mm and (2) S1 scalloping > 3.5. Dural ectasia exists if 1 major or 2 minor criteria are present.Conclusion: MR and CT diagnose dural ectasia with high specificity and sensitivity. Our criteria accurately diagnose dural ectasia in adult Marfan patients.

Thoracolumbar deformity arthrodesis stopping at L5: Fate of the L5-S1 disc, minimum 5-year follow-up

Study Design. A retrospective long-term follow-up study. Objective. Evaluate the fate of L5-S1 disc analyzing subsequent disc degeneration and associated risk factors for degeneration at minimum 5-year follow-up (average 9-year follow-up). Summary of Background Data. Two previous studies reported the results of long deformity fusions terminating at L5 with minimum 2-year follow-up only. Methods. Thirty-one consecutive patients with an average age of 45 years (range, 20–62 years) were fused from the thoracic spine to L5 and were evaluated at a mean follow-up of 9.4 years (range, 5–20.1 year). Patients were evaluated before surgery, after surgery, and latest follow-up with radiographs and Scoliosis Research Society Patient Questionnaire-24 scores. Disc degeneration using validated radiographic Weiner grades. Grade 0 to 1 discs were “healthy” and Grade 2 to 3 were degenerated. Patients with “healthy” discs preoperative that subsequently degenerated were designated subsequent advanced degeneration (SAD). Results. Two out of 31 patients had preoperative advanced degeneration of the L5-S1 disc (Weiner grade 2–3). Three additional patients had an early revision to the sacrum secondary to sagittal imbalance not thought to be related to SAD. Twenty-six out of 31 patients were assessed as “healthy discs” preoperative (Weiner grade 0–1) and were evaluated for SAD. By latest follow-up, L5-S1 SAD developed in 18 of these 26 patients (69%). Risk factors for the development of SAD included long fusions extending into the upper thoracic spine down to L5 (P = 0.02) and having a circumferential lumbar fusion (P = 0.02). Although preoperative sagittal balance was not significantly different between the “healthy” and SAD group, sagittal balance at follow-up was: C7 plumb >5 cm in 67% of SAD patients and only 13% of “healthy” disc patients (P = 0.009). There was a trend toward inferior Scoliosis Research Society Patient Questionnaire-24 pain scores at follow-up in SAD patients (average score 4.1 vs. 3.4, P = 0.13). Eleven out of 30 patients (35%) had subsequent spinal surgery with 7 of 31 (23%) having extension of their fusion to the sacrum. An additional 6 of 31 (19%) were considered for extension to the sacrum but comorbidities precluded surgery (3 patients) or the patients declined further surgery (3 patients). Conclusion. Advanced L5-S1 DDD developed in 69% of deformity patients after long fusions to L5 with 5 to 15 year follow-up. SAD frequently results in significant positive sagittal balance at a minimum 5-year follow-up. Long fusions to the upper thoracic spine down to L5 and circumferential fusion may further promote subsequent L5-S1 disc degeneration.

Pedicle Screw Instrumentation for Adult Idiopathic Scoliosis : An Improvement Over Hook/Hybrid Fixation

Study Design. A matched cohort comparison of adult idiopathic scoliosis (AdIS) patients treated with all pedicle screw constructs compared to hook/hybrid constructs. Objective. To compare clinical and radiographic results of AdIS treatment using all pedicle screw constructs versus hook/hybrid constructs. Summary of Background Data. Pedicle screw instrumentation has demonstrated excellent clinical efficacy in the treatment of pediatric spinal deformity. No prior reports have compared the outcomes of pedicle screw only constructs to hook/hybrid constructs in the treatment of AdIS. Methods. We analyzed 34 consecutive patients undergoing posterior-only correction for AdIS, using pedicle screw instrumentation at minimum 2-year follow-up. Thirty-four matching patients (11 with anterior releases) were selected from a cohort of 58 patients treated with hook/hybrid constructs based on similar age, curve type, magnitude, and fusion levels. Results. Significantly greater curve correction was seen in the pedicle screw compared to the hook/hybrid group (56 vs. 40%, P < 0.01). Coronal and sagittal imbalance were equivalent between the groups (P = 0.91 and 0.23, respectively). Thoracic kyphosis (T5–T12) was maintained in the pedicle screw patients but significantly increased in the hybrid/hook patients over time (P < 0.05). Scoliosis Research Society outcome scores significantly improved in both groups. Blood loss was equivalent but operative time was longer in the hook/hybrid patients. No pedicle screw patients were revised for instrumentation complications with 1 lumbosacral nonunion revised at 5 years postoperative (3% revision rate). Eight of 58 patients among the hook/hybrid cohort underwent 9 revisions for instrumentation failure (n = 3) or nonunion (n = 6) (14% revision rate; P = 0.04). Conclusion. Pedicle screw correction of AdIS is safe and effective. Compared to hook/hybrid constructs, these patients displayed significantly improved correction of the major curve (even in the absence of anterior releases), maintenance of thoracic kyphosis, and a lower revision rate. Similar SRS scores and blood loss were noted. The hook/hybrid patients had significantly longer operative times. The use of BMP-2 in 7 patients and TLIF/ALIF also in 7 of the pedicle screw patients may have decreased the need for revision surgery up to the latest follow-up.