Patrick J. Cahill

Percutaneous treatment of vertebral compression fractures: a meta-analysis of complications.

Study Design and Objective. This study performs a meta-analysis to compare complication rates from vertebroplasty (VP) and kyphoplasty (KP). Summary of Background Data. Recently, the development of VP and balloon KP has been shown to provide symptomatic relief and restoration of sagittal alignment of vertebral compression fractures refractory to medical therapy. Complications in treatment of vertebral compression fractures are rare, however can be potentially devastating. Fortunately, clinical sequelae are rare; however, severe clinical complications from cement extravasation have been reported. Methods. Using PubMed and Ovid, we performed a literature search for “kyphoplasty,” “vertebroplasty,” and “vertebral augmentation.” This search was performed in December 2006. Case reports and reports not available in English were excluded. We categorized complications in 3 categories: (1) procedure-related complications, (2) medical complications, and (3) new vertebral fracture. Cement leakage, asymptomatic and symptomatic, and its locations were recorded. We performed a meta-analysis of complications of all studies. We then repeated the meta-analysis examining only prospective studies. We then used proportion analysis to determine statistical significance. We defined statistical significance as a P value less than 0.05. Results. We identified 121 reports of KP and/or VP that specifically addressed complications. Of these studies, 33 addressed KP and 82 addressed VP (6 reports addressed complications of both). There were 29 reports in which the data appeared to be collected prospectively. Of these, 9 addressed KP and 21 addressed VP. VP was found to have a significantly increased rate of procedure-related complications than KP in the analysis of all studies and only prospective studies. VP also appears to have a significantly higher rate of symptomatic and asymptomatic cement leakage than KP (P < 0.05). The incidence of medical complications was significantly higher in the KP procedure; however, this difference was not observed when analyzing only prospective studies. The incidence of new fracture was significantly higher in the VP procedure; however, this was not observed when analyzing only prospective studies. Conclusion. VP and KP are 2 minimally invasive procedures that have been shown to be effective in the treatment of symptomatic vertebral compression fractures. Although the incidence of adverse events for both VP and KP are low, it appears that VP is associated with a statistically significant increased rate of procedure-related complications and cement extravasation (symptomatic and asymptomatic). Future prospective studies with large patient enrollment will be needed to further validate the finding of this meta-analysis

Autofusion in the immature spine treated with growing rods.

Study Design. Retrospective case review of skeletally immature patients treated with growing rods. Patients received an average of 9.6 years follow-up care. Objective. (1) to identify the rate of autofusion in the growing spine with the use of growing rods; (2) to quantify how much correction can be attained with definitive instrumented fusion after long-term treatment with growing rods; and (3) to describe the extent of Smith-Petersen osteotomies required to gain correction of an autofused spine following growing rod treatment. Summary of Background Data. The safety and use of growing rods for curve correction and maintenance in the growing spine population has been established in published reports. While autofusion has been reported, the prevalence and sequelae are not known. Methods. Nine skeletally immature children with scoliosis were identified who had been treated using growing rods. A retrospective review of the medical records and radiographs was conducted and the following data collected: complications, pre- and postoperative Cobb angles at time of initial surgery (growing rod placement), pre- and postoperative Cobb angles at time of final surgery (growing rod removal and definitive fusion), total spine length as measured from T1–S1, % correction since initiation of treatment and at definitive fusion, total number of surgeries, and number of patients found to have autofusion at the time of device removal. Results. The rate of autofusion in children treated with growing rods was 89%. The average percent of the Cobb angle correction obtained at definitive fusion was 44%. On average, 7 osteotomies per patient were required at the time of definitive fusion due to autofusion. Conclusion. Although growing rods have efficacy in the control of deformity within the growing spine, they also have adverse effects on the spine. Immature spines treated with a growing rod have high rates of unintended autofusion which can possibly lead to difficult and only moderate correction at the time of definitive fusion.

Infection after spinal fusion for pediatric spinal deformity: thirty years of experience at a single institution.

Study Design. A retrospective, consecutive case study of 1571 pediatric patients who underwent spinal deformity surgery and had minimum 2-year follow-up. Objective. To identify (1) the rate of infection after pediatric spinal deformity surgery; (2) the number of surgeries required to treat a postoperative infection after a pediatric spinal deformity surgery; (3) the percentage of patients with a postoperative infection after pediatric spinal deformity surgery who require implant removal to quantify the effect of removal on the deformity; and (4) the microbiology of postoperative infections after pediatric spinal deformity surgery. Summary of Background Data. Several previous reports have discussed the rates of infection after spinal surgery for pediatric spinal deformity. No previous reports have quantified the rate and magnitude of deformity progression after infection in pediatric spinal deformity surgery. Methods. A retrospective review was performed of the medical records and radiographs of all children undergoing surgery for spinal deformity at the Shriners Hospital for Children in Chicago from January 1, 1975, to June 1, 2005. Results. The rate of infection varied based on underlying diagnosis: idiopathic scoliosis 0.5%, myelomeningocele 19.2%, myopathies 4.3%, and cerebral palsy 11.2%. On average, 2 surgeries were required to eradicate the infection. Approximately half of the patients required removal of the instrumentation to treat their infection. Forty-four percent of patients who developed an infection had significant progression of their deformity, with an average increase in deformity magnitude of 27°. Implant removal predisposed patients to progression of deformity. The 3 most common organisms in order were Staphylococcus aureus, S. epidermidis, and Pseudomonas aeruginosa. Conclusion. Infection after spinal deformity in idiopathic scoliosis is rare but is relatively common in neuromuscular conditions. Eradication of infection can be expected, but implant removal is often required. Should implants be totally removed, significant progression of the deformity is possible.

Cervical sagittal plane decompensation after surgery for adolescent idiopathic scoliosis: an effect imparted by postoperative thoracic hypokyphosis

OBJECT Several studies have characterized the relationship among postoperative thoracic, lumbar, and pelvic alignment in the sagittal plane. However, little is known of the relationship between postoperative thoracic kyphosis and sagittal cervical alignment in patients with adolescent idiopathic scoliosis (AIS) treated with all pedicle screw constructs. The authors examined this relationship and associated factors. METHODS A prospective database of pediatric patients with AIS undergoing spinal fusion between 2003 and 2005 was reviewed for those who received predominantly pedicle screw constructs for Lenke Type 1 or Type 2 curves. Parameters analyzed on pre- and postoperative radiographs were the fusion levels; cervical, thoracic, and lumbar sagittal balance; and C-2 and C-7 plumb lines. RESULTS Preoperatively, 6 (Group A) of the 22 patients included in the study had frank cervical kyphosis (mean angle 13.0°) with mean associated thoracic kyphosis of 27.2° (range 16°-37°). Postoperatively, cervical kyphosis (13.0°) remained in the patients in Group A along with mean thoracic kyphosis of 17.7° (range 4°-26°, p < 0.05). Preoperatively, the remaining 16 of 22 patients had neutral to lordotic cervical alignment (mean -13.8°) with thoracic kyphosis (mean 45°, range 30°-76°). Postoperatively, 8 (Group B) of these 16 patients demonstrated cervical sagittal decompensation (> 5° kyphosis), with 6 showing frank cervical kyphosis (10.5°, p < 0.05). In Group B, the mean postoperative thoracic kyphosis was 25.6° (range 7°-49°, p < 0.05). The other 8 patients (Group C) had mean postoperative thoracic kyphosis of 44.1° (range 32°-65°), and there was no cervical decompensation (p < 0.05). CONCLUSIONS The sagittal profile of the thoracic spine is related to that of the cervical spine. The surgical treatment of Lenke Type 1 and 2 curves by using all pedicle screw constructs has a significant hypokyphotic effect on thoracic sagittal plane alignment (19 [86%] of 22 patients). If postoperative thoracic kyphosis is excessively decreased (mean 25.6°, p < 0.05), the cervical spine may decompensate into significant kyphosis.

The use of a transition rod may prevent proximal junctional kyphosis in the thoracic spine after scoliosis surgery: a finite element analysis.

Study Design. Finite element analysis. Objective. Via finite element analysis: (1) to demonstrate the abnormal forces present at the top of a scoliosis construct, (2) to demonstrate the importance of an intact interspinous and supraspinous ligament (ISL/SSL) complex, and (3) to evaluate a transition rod (a rod that has a short taper to a smaller diameter at one end) as an implant solution to diminish these pathomechanics, regardless of the integrity of the ISL/SSL complex. Summary of Background Data. The pathophysiology of increased nucleus pressure and increased angular displacement may contribute to proximal junctional kyphosis. Furthermore, high implant stress can be demonstrated at the upper end of the construct, possibly leading to the risk of implant failure. Methods. A finite element model was constructed to simulate a thoracic spinal fusion. The model was altered to remove the ISL/SSL complex at the level above the construct. Then, the model was altered again by extending the construct one level superior with a transition rod. The angular displacement, the maximum pressure in the nucleus, and stress within the implant were extracted from computational results under 2 conditions: load control and displacement control. The testing was performed with both titanium and stainless steel implants. Results. Pressure in the nucleus and angular displacement are all increased when the ISL/SSL complex is removed immediately above the instrumented levels, whereas the screw pullout force and maximum stress within the screw are decreased. The nucleus pressure increases by more than 50%. The angular displacement increases by 19% to 26%. This absence of the ISL/SSL complex simulates the clinical scenario that occurs when these structures are iatrogenically detached. Abnormal mechanics can be restored to normal level by extending the construct rostral one level with a transition rod. Furthermore, the elevated nucleus pressure and angular displacement noted even when the ISL/SSL complex is intact can be avoided with the use of a transition rod. Under the same bending moment (3 Nm), the nucleus pressure at the level immediately cephalad is up to 23% lower than the pressure in a standard construct. The angular displacement is 18% to 19% less than the standard construct. The maximum implant stress is also decreased by as much as 60%. Conclusion. Finite element modeling suggests that the pathomechanics at the proximal end of a scoliosis construct may be diminished by preserving the ISL/SSL complex and possibly completely eliminated with the use of rods with a diameter transition at the most proximal level.

Bilateral use of the vertical expandable prosthetic titanium rib attached to the pelvis: a novel treatment for scoliosis in the growing spine.

OBJECT Few options exist for the treatment of severe, early onset scoliosis. Goals of treatment include stabilizing curve progression while allowing for normal spine, chest, and lung growth. The vertical expandable prosthetic titanium rib (VEPTR) is a novel device designed to control the spine deformity while permitting lung and spine growth. In this paper the authors report their experience with using bilateral VEPTRs from the ribs to the pelvis for children with severe, early onset scoliosis. METHODS Eleven children were identified who had been treated with bilateral VEPTRs from the ribs to the pelvis. The authors conducted a retrospective review and collected the following data: clinical diagnosis, age at surgery, number of lengthening procedures, and complications. In addition, pre- and postoperative radiographs were reviewed to measure maximum Cobb angle (both thoracic and lumbar), thoracic height, total spine height as measured from T-1 to S-1, thoracic kyphosis (T2-12), and lumbar lordosis (L1-S1). RESULTS The average patient age at surgery was 71 months; the mean preoperative thoracic Cobb angle was 81.7 degrees . This angle was corrected to 50.6 degrees immediately postoperatively, and this correction was maintained; at the most recent follow-up the curves averaged 58 degrees . Similarly, the preoperative kyphosis (T2-12) angle measured 43 degrees preoperatively, 23 degrees immediately postoperatively, and 37 degrees at the most recent follow-up evaluation. The patients underwent a total of 41 lengthening procedures (average 3.7 lengthening procedures per patient), and overall spine length increased from 23.1 cm preoperatively, to 27.3 cm immediately postoperatively, to 29.4 cm at the final follow-up (an average of 25 months). Four (36.4%) of the 11 patients experienced complications. CONCLUSIONS The VEPTR offers a viable treatment option for children with severe, early onset scoliosis. It achieves and maintains spinal deformity correction, while allowing for continued spine and chest-wall growth. Complication rates are similar to those reported for other growing systems.

Special article: Update on the magnetically controlled growing rod: tips and pitfalls.

Magnetically controlled growing rods (MCGR) have become an important treatment option in young patients with spinal deformities. This device allows for gradual lengthening on an outpatient setting with continuous neurological monitoring in an awake patient. With its growing popularity and interest, this study reports the tips, pitfalls, and complications of the MCGR for management of scoliosis. On 3 June 2015 at the University of Hong Kong, 32 participants from 16 regions shared their experience with MCGR. Current indications for surgery include early-onset scoliosis patients. Adolescent idiopathic scoliosis and congenital scoliosis patients have less favourable outcomes. The number of instrumented levels should be minimised, as all instrumented levels must be included in the definitive fusion surgery. Rod contouring is important and owing to the straight portion of the rod housing the magnet, there is limited proximal rod portion for proper contouring, which may predispose to proximal junctional kyphosis. There is currently no consensus on the rod configuration, timing, frequency, technique, and amount of distraction. Risk factors for distraction failure include larger patients, internal magnets too close to each other, and magnets too close to the apex of the major curve. Future studies should resolve the issues regarding the technique of distraction, optimal frequency and amount of distraction per session. More comprehensive cost analyses should be performed.

Clinical outcomes of nitinol staples for preventing curve progression in idiopathic scoliosis.

Summary of Background DataAlthough bracing for idiopathic scoliosis is moderately successful, its efficacy has been called into question and it carries associated psychosocial ramifications. In this study we report the background, rationale, indications, surgical techniques, and early results of vertebral body stapling (VBS) in patients with idiopathic scoliosis. MethodsWe reviewed the literature on growth modulation of the growing spine and the concepts behind the use of VBS as a fusionless strategy. The indications are derived from retrospectively reviewed patients with idiopathic scoliosis treated with VBS followed for a minimum of 2 years. Indications for staple use included: (a) age <13 years in girls and 15 in boys, (b) Risser 0 or 1 and/or 1 year of growth remaining on wrist radiograph, (c) coronal curve <45 degrees with minimal rotation and flexible to <25 degrees on a side bending radiograph, and (d) sagittal thoracic curve <40 degrees. ResultsThoracic curves measuring <35 degrees had a success rate of 77.7%. Curves which reached ⩽20 degrees on first erect radiograph had a success rate of 85.7%. Thoracic curves greater than 35 degrees were not successful and require alternative treatments. Lumbar curves demonstrated a success rate of 86.7%. ConclusionsSome patients with idiopathic scoliosis with moderate curves (25 to 45 degrees) and high risk of progression can be safely treated with VBS as an alternative to bracing. Level of EvidenceLevel III.

The impact of segmental and en bloc derotation maneuvers on scoliosis correction and rib prominence in adolescent idiopathic scoliosis.

OBJECT Idiopathic scoliosis is a pathological process influencing the spinal column in 3 dimensions. Initial surgical treatment focused primarily on correction in the coronal plane, and with improved instrumentation, increasing attention has targeted balancing the sagittal profile. Newer surgical techniques now permit operative corrective forces to also directly address axial rotation. Although several technical variations of direct vertebral body derotation (DVBD) have been devised, no studies have compared outcomes from the differing techniques. The purpose of this study was to describe and compare the differences between segmental and en bloc DVBD. METHODS A large prospectively collected database was queried for patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion and for whom there was a minimum of 2 years of follow-up. In all patients some type of DVBD maneuver was performed (segmental, en bloc, or both). Any patients with concurrent thoracoplasties were excluded. RESULTS The authors identified 188 patients, of whom 120 underwent segmental derotation, 17 en bloc derotation, and 51 both. No significant radiographic or clinical differences existed among the groups preoperatively. The mean preoperative thoracic curve in the entire cohort was 53.1° ± 14.1° and the mean thoracic rib prominence was 14.0° ± 5.5°, whereas the respective postoperative values were 19.3° ± 8.3° and 7.2° ± 4.0°. No significant difference was identified between the various techniques postoperatively, either. However, when comparing intraoperative variables, significant differences were found for operative duration (p = 0.0001), estimated blood loss (p = 0.0081), and volume of blood transfusions (p = 0.041). CONCLUSIONS Although each surgical technique of DBVD may have theoretical benefits and risks, no apparent difference in outcomes was observed between techniques. The concurrent use of both techniques was associated with increased blood loss and operative duration without any appreciable benefit. The surgeon should adopt the derotation technique with which he or she is most comfortable, but concurrent use of both does not appear to improve results.

Direct vertebral body derotation, thoracoplasty, or both: which is better with respect to inclinometer and scoliosis research society-22 scores?

Study Design. Prospective, longitudinal cohort (nonrandomized). Objective. To compare thoracoplasty (Th), direct vertebral body derotation (DVBD), and Th and DVBD with respect to correction of the rib prominence and Scoliosis Research Society (SRS) self-image scores in patients undergoing surgery for adolescent idiopathic scoliosis (AIS). Summary of Background Data. Rib prominence correction is one of the main goals of AIS surgery. Th and DVBD are powerful tools for correction of the rib prominence; however, a paucity of literature exists comparing Th, DVBD, and Th and DVBD. Methods. A prospective longitudinal database was queried to identify patients with AIS who underwent a posterior spinal fusion with pedicle screws and 2 years of follow-up. A total of 326 patients were identified and divided into 3 groups: (1) Th alone (N = 47), (2) DVBD alone (N = 196), and (3) both Th and DVBD (N = 83). Patients were subdivided into categories on the basis of their preoperative inclinometer reading: (1) ⩽9° (mild), (2) 10 to 15° (moderate), and (3) ≥16° (severe). Pre- and postoperative inclinometer readings and SRS self-image scores were compared using analysis of variance. Results. Overall, the groups were similar preoperatively except for the DVBD group having higher percentage of thoracic flexibility. The preoperative rib prominence values were Th = 13.2, DVBD = 14.0, and Th and DVBD = 12.9 (P = 0.27). Taken collectively, the postoperative 2-year inclinometer readings were similar for all 3 groups (Th = 5.2, DVBD = 7.0, Th and DVBD = 5.6; P = 0.66). However, the SRS-22 self-image scores were significantly better for patients having both Th and DVBD (Th = 3.37, DVBD = 3.44, Th and DVBD = 3.76; P < 0.01). When patients were stratified by severity of preoperative rib prominence, all patients with mild prominences achieved similar corrections, although SRS self-image scores were highest in the Th and DVBD group. In patients with larger rib prominences, the addition of Th was necessary for optimal rib prominence correction, but there was no difference in SRS-22 self-image scores. Conclusion. Our results suggest that Th alone, DVBD alone, or both Th and DVBD provide equivalent inclinometer results in patients with mild preoperative rib prominences (⩽9°), but higher SRS-22 self-image scores are achieved using both Th and DVBD. For larger rib prominences, better inclinometer readings are achieved with Th, although SRS-22 self-image scores are comparable.