Analysis of intervertebral discs adjacent to thoracolumbar A3 fractures treated by percutaneous instrumentation and kyphoplasty

INTRODUCTION

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.

MATERIALS AND METHODS

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.

RESULTS

Local kyphosis decreased from 12.4° to 7.3° postoperatively (p<0.0001), 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 (p<0.0001) increased to 8.3° before the instrumentation was removed (p=0.764) and increased to 10.6° (p<0.05) at the last follow-up. The vertebral body compression ratio decreased from 23% to 14% postoperatively (p<0.0001) 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 (p<0.0001). 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.

CONCLUSION

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.

Minimally Invasive Far Lateral Lumbar Interbody Fusion: A Prospective Cohort Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To assess rate and degree of interbody bone fusion and evolution in Oswestry Disability index (ODI) and visual analog scale (VAS) of pain after minimally invasive far lateral lumbar interbody fusion.

METHODS

Twenty-three patients with single-level lumbar instability or degenerative disc were treated by this method and prospectively included. VAS of pain and ODI were evaluated preoperatively and at last follow-up. Computed tomography scan was performed 6 months after surgery to assess interbody fusion.

RESULTS

Between preoperative and 2 years postoperative follow-up, mean VAS decreased by 2.4 points (P < .001); mean ODI improved by 21.8% (P < .001). Computed tomography scan showed fusion in all patients but one. No severe complications were observed.

CONCLUSIONS

Minimally invasive far lateral lumbar interbody fusion resulted in satisfactory clinical and radiological results.

Biomechanical Analysis of Lateral Lumbar Interbody Fusion Constructs with Various Fixation Options: Based on a Validated Finite Element Model

BACKGROUND

Lateral lumbar interbody fusion using cage supplemented with fixation has been used widely in the treatment of lumbar disease. A combined fixation (CF) of lateral plate and spinous process plate may provide multiplanar stability similar to that of bilateral pedicle screws (BPS) and may reduce morbidity. The biomechanical influence of the CF on cage subsidence and facet joint stress has not been well described. The aim of this study was to compare biomechanics of various fixation options and to verify biomechanical effects of the CF.

METHODS

The surgical finite element models with various fixation options were constructed based on computed tomography images. The lateral plate and posterior spinous process plate were applied (CF). The 6 motion modes were simulated. Range of motion (ROM), cage stress, endplate stress, and facet joint stress were compared.

RESULTS

For the CF model, ROM, cage stress, and endplate stress were the minimum in almost all motion modes. Compared with BPS, the CF reduced ROM, cage stress, and endplate stress in all motion modes. The ROM was reduced by more than 10% in all motion modes except for flexion; cage stress and endplate stress were reduced more than 10% in all motion modes except for rotation-left. After interbody fusion, facet joint stress was reduced substantially compared with the intact conditions in all motion modes except for flexion.

CONCLUSIONS

The combined plate fixation may offer an alternative to BPS fixation in lateral lumbar interbody fusion.

Comparison of Open Versus Percutaneous Pedicle Screw Fixation Using the Sextant System in the Treatment of Traumatic Thoracolumbar Fractures

STUDY DESIGN

We retrospectively reviewed 100 patients who were posterior stabilized without graft fusion. Using the Sextant system, 22 patients underwent minimally invasive short-segment 4-pedicle screw fixation (MIF4) and 39 patients underwent minimally invasive short-segment combined with intermediate screws fixation, that is, 6-pedicle screw fixation (MIF6). The conventional open posterior short-segment 4-pedicle screw fixation (OPF4) technique was used in 39 patients.

OBJECTIVE

To evaluate the feasibility, safety, and efficacy of percutaneous pedicle screw fixation using the Sextant system in the treatment of traumatic thoracolumbar fractures compared with the conventional open posterior short-segment pedicle screw fixation technique.

SUMMARY OF BACKGROUND DATA

To the best of our knowledge, the clinical and radiographic outcomes of MIF4, MIF6 with polyaxial pedicle screws, and OPF4 with monoaxial pedicle screws have not been compared in the treatment of thoracolumbar fractures.

METHODS

Visual analogue scores (VAS), Oswestry disability index (ODI) scores, clinical outcomes including surgical blood loss, operation time, and postoperative hospital stay, sagittal Cobb angle, vertebral body angle, and anterior height of the fractured vertebrae were compared among the 3 groups.

RESULTS

Significant postoperative improvements, relative to baseline, were observed in the VAS and ODI scores (P<0.05 each). There were no significant differences between the MIF4 and MIF6 groups in clinical outcomes, including surgical blood loss, operation time, postoperative hospital stay, VAS, and ODI scores (P>0.05 each). However, there were significant differences between both MIF groups and the OPF group (P<0.05 each). Significant improvements were observed in the sagittal Cobb angle, vertebral body angle, and anterior height of the fractured vertebrae (P<0.05 each). During follow-up, however, the correction loss of the sagittal Cobb angle was smallest in the MIF6 group (P<0.05).

CONCLUSIONS

Minimally invasive posterior stabilization using the Sextant system resulted in reduced injury compared with the open surgery, during both the internal fixation surgery and the implant removal surgery. Percutaneous screw fixation through the pedicle of the fractured vertebra is superior to the conventional OPF4 technique in correcting kyphotic deformities, and can be performed without any extra procedures.

Outcomes of percutaneous pedicle screw fixation for spinal trauma and tumours

We investigated the clinical and radiological results of percutaneous pedicle screw fixation in the management of spinal trauma and metastatic tumours. A retrospective analysis was performed on a series of 14 patients who were operated on from March 2009 to November 2011 by a single surgeon (RJM). Following a radiological review (CT scan/MRI), six patients underwent short segment fixation, while the remaining underwent long segment fixation. All patients had routine follow-ups at 4, 6, 12months, and annually thereafter. Clinical examinations were conducted preoperatively and postoperatively, and the length of operation, blood loss, and postoperative pain relief were recorded. There was a single patient with an incision site complication. The mean blood loss was 269mL. All of the parameters demonstrated no significant differences between the trauma and the tumour groups (p=0.10). The neurological power scores improved for all patients, with the largest increase being from a score of 2 to 4. At follow-up, the majority of patients had returned to their previous activities and had reduced pain scores. One patient suffered high pain levels from other medical conditions that were not related to the operation. Minimally invasive pedicle screw fixation is a suitable option for patients with spinal tumours and fractures, with acceptable safety and efficacy in this small retrospective patient series. We have seen favourable results in our patients, who have experienced an increased quality of life following their surgery.

Minimally invasive percutaneous screw fixation of traumatic spondylolisthesis of the axis

OBJECT

Most cases of traumatic spondylolisthesis of the axis (hangman's fracture) can be treated nonoperatively with reduction and subsequent immobilization in a rigid cervical collar or halo. However, in some instances, operative management is necessary and can be accomplished by using either anterior or posterior fusion techniques. Because open posterior procedures can result in significant blood loss, pain, and limited cervical range of motion, other less invasive options for posterior fixation are needed. The authors describe a minimally invasive, navigation-guided technique for surgical treatment of Levine-Edwards (L-E) Type II hangman's fractures.

METHODS

For 5 patients with L-E Type II hangman's fracture requiring operative reduction and internal fixation, percutaneous screw fixation directed through the fracture site was performed. This technique was facilitated by use of intraoperative 3D fluoroscopy and neuronavigation.

RESULTS

Of the 5 patients, 2 were women, 3 were men, and age range was 46–67 years. No intraoperative or postoperative complications occurred. All patients wore a rigid cervical collar, and flexion-extension radiographs were obtained at 6 months. For all patients, dynamic imaging demonstrated a stable construct.

CONCLUSIONS

L-E type II hangman's fractures can be safely repaired by using percutaneous minimally invasive surgical techniques. This technique may be appropriate, depending on circumstances, for all L-E Type I and II hangman's fractures; however, the degree of associated ligament injury and disc disruption must be accounted for. Percutaneous fixation is not appropriate for L-E Type III fractures because of significant displacement and ligament and disc disruption. This report is meant to serve as a feasibility study and is not meant to show superiority of this procedure over other surgical options.

Posterior percutaneous reduction and fixation of thoraco-lumbar burst fractures

BACKGROUND

Treatment of A3 thoraco-lumbar and lumbar spinal fractures nowadays remains a controversial issue. Percutaneous techniques are becoming very popular in the last few years to reduce the approach-related morbidity associated with conventional techniques.

HYPOTHESIS

Purpose of the study was to analyze the clinical and radiological outcome of patients who underwent percutaneous posterior fixation without fusion for the treatment of thoraco-lumbar and lumbar A3 fractures.

MATERIALS AND METHODS

Sixty-three patients, having sustained a single-level thoraco-lumbar fracture, underwent short segment percutaneous instrumentation and were retrospectively analyzed. sagittal index (SI) was calculated in all patients. Clinical and functional outcome were evaluated by Visual Analog Scale (VAS), Oswestry Disability Index (ODI) and Short Form General Health Status (SF-36).

RESULTS

Average operative blood loss was 82 mL (50-320). Mean pre-operative SI in the thoraco-lumbar segment was 13.3° decreased to 5.8° in the immediate postoperative with a mean deformity correction of 7.5. Mean pre-operative SI in the lumbar segment was 16.5° decreased to 11.3° in the immediate postoperative with a mean deformity correction of 5.2. Not statistically significant correction loss was registered at 1-year minimum follow-up. Constant clinical conditions improvement in the examined patients was observed.

CONCLUSION

Percutaneous pedicle screw fixation for A3 thoraco-lumbar and lumbar spinal fractures is a reliable and safe procedure.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Biomechanics of lateral lumbar interbody fusion constructs with lateral and posterior plate fixation: laboratory investigation

OBJECT

Lumbar interbody fusion is indicated in the treatment of degenerative conditions. Laterally inserted interbody cages significantly decrease range of motion (ROM) compared with other cages. Supplemental fixation options such as lateral plates or spinous process plates have been shown to provide stability and to reduce morbidity. The authors of the current study investigate the in vitro stability of the interbody cage with a combination of lateral and spinous process plate fixation and compare this method to the established bilateral pedicle screw fixation technique.

METHODS

Ten L1-5 specimens were evaluated using multidirectional nondestructive moments (± 7.5 N · m), with a custom 6 degrees-of-freedom spine simulator. Intervertebral motions (ROM) were measured optoelectronically. Each spine was evaluated under the following conditions at the L3-4 level: intact; interbody cage alone (stand-alone); cage supplemented with lateral plate; cage supplemented with ipsilateral pedicle screws; cage supplemented with bilateral pedicle screws; cage supplemented with spinous process plate; and cage supplemented with a combination of lateral plate and spinous process plate. Intervertebral rotations were calculated, and ROM data were normalized to the intact ROM data.

RESULTS

The stand-alone laterally inserted interbody cage significantly reduced ROM with respect to the intact state in flexion-extension (31.6% intact ROM, p < 0.001), lateral bending (32.5%, p < 0.001), and axial rotation (69.4%, p = 0.002). Compared with the stand-alone condition, addition of a lateral plate to the interbody cage did not significantly alter the ROM in flexion-extension (p = 0.904); however, it was significantly decreased in lateral bending and axial rotation (p < 0.001). The cage supplemented with a lateral plate was not statistically different from bilateral pedicle screws in lateral bending (p = 0.579). Supplemental fixation using a spinous process plate was not significantly different from bilateral pedicle screws in flexion-extension (p = 0.476). The combination of lateral plate and spinous process plate was not statistically different from the cage supplemented with bilateral pedicle screws in all the loading modes (p ≥ 0.365).

CONCLUSIONS

A combination of lateral and spinous process plate fixation to supplement a laterally inserted interbody cage helps achieve rigidity in all motion planes similar to that achieved with bilateral pedicle screws.

Resultados postoperatorios inmediatos y a largo plazo de un abordaje mini-invasivo para la corrección de escoliosis idiopática del adolescente

OBJETIVO: Analizar los resultados de una nueva técnica quirúrgica mínimamente invasiva (MIS, por el inglés "minimally invasive surgery") por vía posterior aislada para la corrección quirúrgica de la escoliosis idiopática del adolescente (EIA). MÉTODOS: Se comparan dos grupos de pacientes con EIA tipo 1A de Lenke, similares en cuanto a edad, género, ángulo de Cobb, ápex de la curva, rotación vertebral, cifosis torácica, niveles de fusión, tipo de instrumentación y seguimiento. El Grupo 1 fue tratado con la técnica mínimamente invasiva que describiremos y el Grupo 2, de forma convencional. Se analizaron el tiempo quirúrgico, la pérdida sanguínea intraoperatoria, los requerimientos analgésicos en el postoperatorio inmediato, la estancia hospitalaria, la tasa de mal posición de los tornillos, la pérdida de corrección, la tasa de pseudoartrosis y la movilización de implantes. RESULTADOS: En el Grupo 1 (MIS) la cirugía disminuyó significativamente el sangrado y presentó menor número de casos de tornillos mal posicionados en la concavidad que el grupo tratado de forma convencional; sin embargo la cirugía tuvo mayor duración. Ambos grupos tuvieron requerimientos analgésicos similares y la estancia hospitalaria no presentó diferencias. A largo plazo en ninguno de los dos grupos se encontraron casos de no-unión, pérdidas de corrección, ni movilización de los implantes. CONCLUSIONES: La técnica MIS demostró prolongación del tiempo quirúrgico y menores pérdidas hemáticas, sin disminuir los requerimientos analgésicos ni la estancia hospitalaria. La corrección inicial de la escoliosis por la convexidad disminuyó la incidencia de tornillos mal posicionados en la concavidad, no dio lugar a pérdidas de corrección, movilización de implantes y no-unión.

Postoperative lumbar plexus injury after lumbar retroperitoneal transpsoas minimally invasive lateral interbody fusion

STUDY DESIGN

Retrospective review.

OBJECTIVE

To evaluate the motor and sensory deficit rate after the lumbar retroperitoneal transpsoas minimally invasive lateral interbody fusion (MIS LIF) by reviewing a single surgeon's experience.

SUMMARY OF BACKGROUND DATA

The MIS LIF is an increasingly used alternative to traditional open anterior or posterior operations to treat a host of spinal disorders. It has many advantages, but the potential for immediate postoperative thigh numbness, pain, and potential motor weakness has been reported. Published rates range widely in part because previous studies have based patient outcomes on data from different surgeons using different techniques.

METHODS

An institutional review board-approved, retrospective review of a prospectively collected database was conducted. Seventy-one consecutive patients who underwent this procedure between L1 and L5 during a 3-year period met criteria and were included. Postoperative clinical examinations immediately after surgery and during routine follow-up intervals were examined.

RESULTS

There was a 19.1% (14/71) rate of immediate postoperative ipsilateral thigh numbness during the study period. The annual rates of numbness progressively decreased annually. There was a 26.1% (6/23), 25% (5/20), and 10.7% (3/28) rate for 2008, 2009, and 2010, respectively. All patients with numbness had a fusion construct that involved L4-L5. More than half the patients, 54.9% (39/71), had immediate postoperative ipsilateral iliopsoas or quadriceps weakness. Of these, the vast majority had resolution by 3 months (92.3%), and all had complete resolution by 2 years.

CONCLUSION

The lumbar retroperitoneal transpsoas MIS LIF is a safe alternative to traditional open operations for many spinal conditions. As with most minimally invasive techniques, there is a learning curve to be overcome to minimize the risk of iatrogenic nerve injuries. Our refined technique of the MIS LIF during a 3-year period has led to a significant reduction of the incidence of postoperative numbness of nearly 60% (from 26.1%-10.7%).

Correcção de escoliose lombar degenerativa por técnica minimamente invasiva

A terapêutica cirúrgica da escoliose degenerativa consiste habitualmente em instrumentações e fusões mais ou menos extensas e associa-se a morbilidade significativa. A evolução tecnológica tem aberto caminho a técnicas menos invasivas que permitem obter resultados sobreponíveis aos das técnicas tradicionais minimizando a agressão cirúrgica. Descreve-se o caso de uma paciente do sexo feminino, de 63 anos, submetida a descompressão lombar posterior, em Janeiro de 2009, por alterações degenerativas marcadas. Poucos meses após a cirurgia a paciente referiu aumento das lombalgias e ciatalgia direita. O estudo imagiológico demonstrou agravamento de escoliose degenerativa L2-L5 associada a extrusão discal L2-L3 direita calcificada, fractura bilateral dos pedículos de L3 e espondilolistese degenerativa grau 1 L5-S1. Foi submetida a reintervenção cirúrgica por técnica minimamente invasiva consistindo em TLIF's L2-L3, L3-L4, L4-L5 e L5-S1 e fixação transpedicular L2-S1 bilateral, com correcção da deformidade no plano sagital e coronal. O caso clínico apresentado ilustra o potencial das abordagens minimamente invasivas no tratamento cirúrgico de escolioses degenerativas, devendo ser uma opção sempre presente considerando os benefícios potenciais para o paciente.

Correction of Coronal Imbalance in Degenerative Lumbar Spine Disease Following Direct Lateral Interbody Fusion (DLIF)

Objective

The authors have recently been using a surgical technique of minimally invasive direct lateral interbody fusion (DLIF) for correcting of coronal imbalance. The purpose of this study was to evaluate the surgical outcome and complication of DLIF.

Methods

We undertook retrospective analysis of a consecutive series of 8 DLIF procedures in Degenerative lumbar spine disease since May 2011. Four patients underwent DLIF only, and the others underwent combined DLIF and posterior fixation. Data on intra- and postoperative complications were collected. The pre- and postoperative X-rays were reviewed. We investigated coronal deformity, Cobb's angle, and apical vertebral translation (AVT). The mean follow-up period was months with a range of 2 to 8 months.

Results

A mean preoperative coronal Cobb's angle was 21.8° (range 11.5-32.4°). Following after DLIF, the mean Cobb's angle was decreased to 13.0° (range 2.9-21.5°). Following additional posterior screw fixation, mean Cobb's angle was further decreased to 7.4° (range 2.9-13.2°). A mean preoperative AVT was 2.0 cm(range 0.6-3.5 cm), and improved to 1.4 cm(range 0.3-2.4 cm) and 0.8 cm(range 0.2-1.8 cm) postoperatively (DLIF and, posterior fixation respectively). One patient (12.5%) showed cage migration during follow-up period. Two patients (25%) developed motor weakness, and 4 patients (50%) experienced postoperative thigh paresthesias or dysesthesias. During follow up period, motor weakness had resolved in 1 patient. Sensory symptoms were improved in all patients at the last follow-up.

Conclusion

Degenerative lumbar disease can be effectively corrected by DLIF with acceptable complications.

Initial clinical outcomes of minimally invasive lateral lumbar interbody fusion in degenerative lumbar disease: a preliminary report on the experience of a single institution with 30 cases

Objective

The object of this study was to evaluate the clinical and radiological outcomes of minimally invasive lateral lumbar interbody fusion.

Methods

This study included 30 patients who underwent minimally invasive lateral lumbar interbody fusion at our hospital between May 2011 and February 2012 for the following diagnoses: degenerative disc disease, adjacent-segment degeneration, degenerative spondylolisthesis and lumbar degenerative scoliosis. Pain assessment was reported from 0 to 10 using a subjective visual analog scale (VAS) upon admission and at every follow-up day. Lumbar X-rays were obtained in the standing position upon admission and the 1st and 5th postoperative day, and at every follow-up day after the operation. The heights of the intervertebral disc space and neural foramen were measured using an electronic caliper with the PACS software. The surgical outcome was assessed as excellent, good, fair or poor using the Odom scale at the last follow-up.

Results

The mean VAS for low back pain were 4.93±1.47 on admission and 2.01±1.35 at last follow-up, respectively, and for leg pain, the scores were 4.87±2.16 on admission and 1.58±1.52 at last follow-up. The mean height of intervertebral disc space increased by 34% (7.93±2.33 preoperatively, and 11.09±4.33 immediately after surgery, p<0.01). The mean height of neural foramen also increased by 6.4% without any statistical significance (19.17±2.84 preoperatively, and 20.49±4.50 immediately after the surgery). Minimally invasive lateral lumbar interbody fusion was successful in 27 patients (90%) at last follow-up. Surgical complications were reported as transient postoperative thigh sensory changes (5 patients, 16.7%), transient psoas muscle weakness (3 patients, 10%), cage migration (2 patients, 6.7%), lumbar plexus injury (1 patient, 3.3%), and pain aggravation (1 patient, 3.3%).

Conclusion

The minimally invasive lateral lumbar interbody fusion is a safe and effective procedure for treating degenerative lumbar disease with good outcomes and moderate complications. Further follow-up is necessary to establish its safety and efficacy.

Subsidence of polyetheretherketone intervertebral cages in minimally invasive lateral retroperitoneal transpsoas lumbar interbody fusion

STUDY DESIGN

A retrospective review.

OBJECTIVE

The objective is to evaluate subsidence related to minimally invasive lateral retroperitoneal lumbar interbody fusion by reviewing our experience with this procedure.

SUMMARY OF BACKGROUND DATA

Polyetheretherketone intervertebral cages of different lengths, widths, and heights filled with various allograft types are commonly used as spacers in lumbar fusions. Subsidence is a potential complication. To date, there are no published reports specifically addressing subsidence, because it relates to a series of patients undergoing minimally invasive lateral retroperitoneal transpsoas lumbar interbody fusion.

METHODS

An institutional review board-approved, retrospective review of a prospectively collected database was conducted. One hundred forty consecutive patients who underwent this procedure between L1 and L5 during a 2-year period were included. All patients had T scores of -2.5 or more. Postoperative radiographs during routine follow-ups were reviewed for subsidence, defined as any violation of the vertebral end plate.

RESULTS

Radiographical subsidence occurred in 14.3% (20 of 140), whereas clinical subsidence occurred in 2.1%. Subsidence occurred in 8.8% (21 of 238) of levels fused. Construct length had a significant positive correlation with increasing subsidence rates. Subsidence rates decreased progressively with lower levels in the lumbar spine, but had a higher than expected rate at L4-L5. Subsidence rates of 14.1% (19 of 135) and 1.9% (2 of 103) were associated with 18-and 22-mm-wide cages, respectively. No significant trends were observed with cage lengths. Supplemental lateral plates had a higher rate of subsidence than bilateral pedicle screws. Subsidence occurred at the superior end plate 70% of the time.

CONCLUSION

The use of wider intervertebral cages leads to a significantly lower rate of subsidence, but a longer cage does not necessarily offer a similar advantage. Wide cages are protective against subsidence, and the widest cages should be used whenever feasible for interbody fusion in the lumbar spine to protect indirect compression and promote arthrodesis.

Complications of lateral plating in the minimally invasive lateral transpsoas approach

Object

The aim of this study was to review the authors' experience with 101 cases over the past 3 years with minimally invasive lateral interbody fusion using a lateral plate. Their main goal was to specifically look for hardware-associated complications. Three cases of hardware failure and 3 cases of vertebral body (VB) fractures associated with lateral plate placement are reported. The authors also review the literature pertaining to lateral plates and related complications.

Methods

This study is a retrospective review of a database of patients who underwent minimally invasive lateral interbody fusion in the thoracolumbar spine during a 3-year period.

Results

Six complications were identified, resulting in an incidence of 5.9%. Three hardware failures, 2 coronal plane VB fractures, and 1 lateral VB fracture were identified. All complications occurred in multilevel cases. All cases presented with recurrent back pain except one, which was identified incidentally.

Conclusions

Minimally invasive lateral interbody fusion is a safe and direct technique that is practical, especially when trying to avoid other approaches for hardware insertion, and it also avoids the complications associated with other types of instrumentation such as pedicle screws. Careful consideration during patient selection and during the operation will aid in the avoidance of complications.

An attempt at clinically defining and assessing minimally invasive surgery compared with traditional "open" spinal surgery

Background

The goal of this editorial and literature review is to define the term “minimally invasive surgery” (MIS) as it relates to the spine and characterize methods of measuring parameters of a spine MIS technique.

Methods

This report is an analysis of 105,845 cases of spinal surgery in unmatched series and 95,161 cases in paired series of open compared with MIS procedures performed by the same surgeons to develop quantitative criteria to analyze the success of MIS.

Results

A lower rate of deep infection proved to be a key differentiator of spinal MIS. In unmatched series the infection rate for 105,845 open traditional procedures ranged from 2.9% to 4.3%, whereas for MIS, the incidence of infection ranged from 0% to 0.22%. For matched paired series with the open and MIS procedures performed by the same surgeons, the rate of infection in open procedures ranged from 1.5% to 10%, but for spine MIS, the rate of deep infection was much lower, at 0% to 0.2%. The published ranges for open versus MIS infection rates do not overlap or even intersect, which is a clear indication of the superiority of MIS for one specific clinical outcome measure (MIS proves superior to open spine procedures in terms of lower infection rate).

Conclusions

It is difficult, if not impossible, to validate that an operative procedure is “less invasive” or “more minimally invasive” than traditional surgical procedures unless one can establish a commonly accepted definition of MIS. Once a consensus definition or precise definition of MIS is agreed upon, the comparison shows a higher infection rate with traditional spinal exposures versus MIS spine procedures.

Minimally invasive multi-level posterior lumbar interbody fusion using a percutaneously inserted spinal fixation system : technical tips, surgical outcomes

OBJECTIVE

There are technical limitations of multi-level posterior pedicle screw fixation performed by the percutaneous technique. The purpose of this study was to describe the surgical technique and outcome of minimally invasive multi-level posterior lumbar interbody fusion (PLIF) and to determine its efficacy.

METHODS

Forty-two patients who underwent mini-open PLIF using the percutaneous screw fixation system were studied. The mean age of the patients was 59.1 (range, 23 to 78 years). Two levels were involved in 32 cases and three levels in 10 cases. The clinical outcome was assessed using the visual analog scale (VAS) and Low Back Outcome Score (LBOS). Achievement of radiological fusion, intra-operative blood loss, the midline surgical scar and procedure related complications were also analyzed.

RESULTS

The mean follow-up period was 25.3 months. The mean LBOS prior to surgery was 34.5, which was improved to 49.1 at the final follow up. The mean pain score (VAS) prior to surgery was 7.5 and it was decreased to 2.9 at the last follow up. The mean estimated blood loss was 238 mL (140-350) for the two level procedures and 387 mL (278-458) for three levels. The midline surgical scar was 6.27 cm for two levels and 8.25 cm for three level procedures. Complications included two cases of asymptomatic medial penetration of the pedicle border. However, there were no signs of neurological deterioration or fusion failure.

CONCLUSION

Multi-level, minimally invasive PLIF can be performed effectively using the percutaneous transpedicular screw fixation system. It can be an alternative to the traditional open procedures.

Minimally invasive lateral retropleural thoracolumbar approach: cadaveric feasibility study and report of 4 clinical cases

BACKGROUND

Traditional anterior and posterior approaches to the thoracolumbar spine are associated with significant morbidity. In an effort to eliminate these drawbacks, minimally invasive retropleural approaches have been developed.

OBJECTIVE

To demonstrate the feasibility and clinical experience of a minimally invasive lateral retropleural approach to the thoracolumbar spine.

METHODS

Seven cadaveric dissections were performed in 7 fresh specimens to determine the feasibility of the technique. In each specimen, the lateral aspect of the vertebral body was accessed retropleurally, and a corpectomy was performed. Intraprocedural fluoroscopy and postoperative computed tomography were used to assess the extent of decompression. As an adjunct, 3 clinical cases of thoracic fractures and 1 neurofibroma were treated with this minimally invasive approach. Operative results, complications, and early outcomes were assessed.

RESULTS

In the cadaveric study, adequate exposure was obtained to perform a lateral corpectomy and to allow interbody grafting between the adjacent vertebral bodies. The procedures were successfully performed in the 4 clinical cases without conversion to conventional approaches. A pleural tear was noted in the first clinical case, and a chest tube was placed without any long-term sequelae.

CONCLUSION

Our early experience suggests that the minimally invasive lateral retropleural approach allows adequate vertebrectomy and canal decompression without the tissue disruption associated with posterolateral approaches. This approach may improve the complication rates that accompany open or endoscopic approaches for thoracolumbar corpectomies.

Systems for long-segment percutaneous spinal fixation: technical feasibility for various indications

SUMMARY OF BACKGROUND DATA

New methods of spinal percutaneous fixation are developing very rapidly. However, few studies to date have focused on long-segment methods of instrumentation.

OBJECTIVE

To report the technical feasibility of long-segment percutaneous stabilization for various indications.

METHODS

The study included 24 patients with a mean age of 58 years (range 38-79). The etiologies included trauma, infection, tumors, or pathology secondary to degenerative lumbar scoliosis. The damaged vertebrae ranged from T5 to L4. All of the patients underwent posterior percutaneous long-segment fixation. When necessary, the anterior spinal column was stabilized by balloon kyphoplasty or via anterior approach. The results obtained were analyzed on the basis of clinical and radiological criteria.

RESULTS

The constructs involved four levels on average per patient, located between T3 and S1. No extra-pedicular misplacements were observed. Two technical difficulties were noticed without clinical consequences. A significant improvement in the pain levels was obtained in all the patients in this series.

CONCLUSIONS

Long-segment percutaneous fixation was found to be technically feasible and to considerably improve the patients' spinal deformations. When associated with balloon kyphoplasty, this intervention seems to provide less loss of correction than previous methods, and posterior fusion was therefore not required. As with all new methods, there is a learning curve, and the indications have to be strictly observed. Further studies need to be performed, however, with a longer follow-up to confirm the absence of long-term complications.

An analysis of postoperative thigh symptoms after minimally invasive transpsoas lumbar interbody fusion

OBJECTIVE

The minimally invasive transpsoas interbody fusion technique requires dissection through the psoas muscle, which contains the nerves of the lumbosacral plexus posteriorly and genitofemoral nerve anteriorly. Retraction of the psoas is becoming recognized as a cause of transient postoperative thigh pain, numbness, paresthesias, and weakness. However, few reports have described the nature of thigh symptoms after this procedure.

METHODS

The authors performed a review of patients who underwent the transpsoas technique for lumbar spondylotic disease, disc degeneration, and spondylolisthesis treated at a single academic medical center. A review of patient charts, including the use of detailed patient-driven pain diagrams performed at equal preoperative and follow-up intervals, investigated the survival of postoperative thigh pain, numbness, paresthesias, and weakness of the iliopsoas and quadriceps muscles in the follow-up period on the ipsilateral side of the surgical approach.

RESULTS

Over a 3.2-year period, 59 patients underwent transpsoas interbody fusion surgery. Of these, 62.7% had thigh symptoms postoperatively. New thigh symptoms at first follow-up visit included the following: burning, aching, stabbing, or other pain (39.0%); numbness (42.4%); paresthesias (11.9%); and weakness (23.7%). At 3 months postoperatively, these percentages decreased to 15.5%, 24.1%, 5.6%, and 11.3%, respectively. Within the patient sample, 44% underwent a 1-level, 41% a 2-level, and 15% a 3-level transpsoas operation. While not statistically significant, thigh pain, numbness, and weakness were most prevalent after L4-5 transpsoas interbody fusion at the first postoperative follow-up. The number of lumbar levels that were surgically treated had no clear association with thigh symptoms but did correlate directly with surgical time, intraoperative blood loss, and length of hospital stay.

CONCLUSIONS

Transpsoas interbody fusion is associated with high rates of immediate postoperative thigh symptoms. While larger, prospective studies are necessary to validate these findings, the authors found that half of the patients had symptom resolution at approximately 3 months postoperatively and more than 90% by 1 year.

Stimulus-evoked electromyography testing of percutaneous pedicle screws for the detection of pedicle breaches: a clinical study of 409 screws in 93 patients

Object

Percutaneous pedicle screws have recently become popularized for lumbar spinal fixation. However, successful anatomical hardware placement is highly dependent on intraoperative imaging. In traditional open surgery, stimulus-evoked electromyography (EMG) responses can be useful for detecting pedicle screw breaches. The use of insulated sleeves for percutaneous screws has allowed for EMG testing in minimally invasive surgery; however, no reports on the reliability of this testing modality have been published.

Methods

A total of 409 lumbar percutaneous pedicle screws were placed in 93 patients. Levels of instrumentation included L-1 (in 12 patients), L-2 (in 34), L-3 (in 44), L-4 (in 120), L-5 (in 142), and S-1 (in 57 patients). Intraoperative EMG stimulation thresholds were obtained using insulating sleeves over a metallic tap prior to final screw placement. Data were compared with postoperative fine-cut CT scans to assess pedicle screw placement. Data were collected prospectively and analyzed retrospectively.

Results

There were 5 pedicle breaches (3 medial and 2 lateral; 3 Grade 1 and 2 Grade 2 breaches) visualized on postoperative CT scans (1.2%). Two of these breaches were symptomatic. In 2 instances, intraoperative thresholds were the sole basis for screw trajectory readjustment, which resulted in proper placement on postoperative imaging. Thirty-five screw trajectories were associated with a threshold of less than 12 mA. However, all breaches were associated with thresholds of greater than 12 mA. Using thresholds below 12 mA as the indicator of a screw breach, this resulted in a sensitivity of 0.0, specificity of 90.3, positive predictive value of 0.0, and negative predictive value of 0.98. Utilizing a threshold of any decreased stimulus (< 20 mA) would have detected 60% of breaches, with a mean threshold of 16.25 mA.

Conclusions

While these data are limited by the low number of radiographic breaches, it appears that tap stimulation with an insulating sleeve may not be reliable for detecting low-grade radiographically breached pedicles using typical stimulation thresholds (< 12 mA). Imaging-based modalities remain more reliable for assessing percutaneous pedicle screw trajectories until more robust and sensitive electrophysiological testing methods can be devised.

Less Invasive Surgical Correction of Adult Degenerative Scoliosis, Part I

BACKGROUND

Adult scoliosis is a condition with increasing prevalence and medical and socioeconomic importance. Surgery is fraught with a significant complication rate in an elderly multimorbid patient population.

OBJECTIVE

To assess technical feasibility and radiographic results of image-guided less invasive correction of adult degenerative scoliosis.

METHODS

Thirty individuals (age, 64–88 years) with progressive deformity (coronal Cobb angles &gt; 25° and &lt; 85°), intractable back pain, radiculopathy, or neurogenic claudication were treated by less invasive decompression and fusion (unilateral transforaminal interbody cage instrumentation and bilateral facet fusions) with recombinant human bone morphogenetic protein-2, spanning 3 to 8 segments (average, 6 segments), using biplanar fluoroscopy or intraoperative computed tomography (iCT)—based navigation. Accuracy of screw placement, curve correction, and fusion rate were evaluated during a mean follow-up of 19.6 months.

RESULTS

With 415 screws implanted, misplacement (grade II or greater) was not observed, and no implants required revision. Spinal iCT with automated registration required 17.5 ± 8.5 minutes (single registration for all segments); monosegmental bilateral screw insertion required 6.8 ± 3.4 minutes. Mean sagittal (coronal) Cobb angle correction was 44.8 ± 10.7° (31.7 ± 13.7°). Mean lumbar lordosis increased from 8.8 ± 8.9° to −36 ± 6.9°, and sagittal balance was reduced from 31.6 ± 15.2 to 8 ± 8.4 mm. Solid fusion was confirmed in 90% of instrumented segments at 16 months. Average radiation dose to the surgeon was 0.025 mSv for single-level transforaminal lumbar interbody fusion with fluoroscopic guidance vs 0 mSv with iCT navigation.

CONCLUSION

Instrumented correction of adult deformity was significantly facilitated by iCT navigation, eliminating radiation exposure to the surgeon. Intraoperative biplanar CT scout views including pelvis and shoulders allow comprehensive assessment of multiplanar deformity correction. Fusion rates obtained with less invasive access equal those of conventional open technique.

An analysis of the differences in the acute hospitalization charges following minimally invasive versus open posterior lumbar interbody fusion

OBJECT

Minimally invasive spine (MIS) procedures are increasingly being recognized as equivalent to open procedures with regard to clinical and radiographic outcomes. These techniques are also believed to result in less pain and disability in the immediate postoperative period. There are, however, little data to assess whether these procedures produce their intended result and even fewer objective data to demonstrate that they are cost effective when compared with open surgery.

METHODS

The authors performed a retrospective analysis of hospital charges for 1- and 2-level MIS and open posterior interbody fusion for lumbar spondylotic disease, disc degeneration, and spondylolisthesis treated at a single academic medical center. Patients presenting with bilateral neurological symptoms were treated with open surgery, and those with unilateral symptoms were treated with MIS. Overall hospital charges and surgical episode-related charges, length of stay (LOS), and discharge status were obtained from the hospital finance department and adjusted for multi-/single-level surgeries.

RESULTS

During a 14-month period, 74 patients (mean age 55 years) were treated. The series included 59 single-level operations (75% MIS and 25% open), and 15 2-level surgeries (53% MIS and 47% open). The demographic profile, including age and Charlson Comorbidity Index, were similar between the 4 groups. The mean LOS for patients undergoing single-level surgery was 3.9 and 4.8 days in the MIS and open cases, respectively (p = 0.017). For those undergoing 2-level surgery, the mean LOS was 5.1 for MIS versus 7.1 for open surgery (p = 0.259). With respect to hospital charges, single-level MIS procedures were associated with an average of $70,159 compared with $78,444 for open surgery (p = 0.027). For 2-level surgery, mean charges totalled $87,454 for MIS versus $108,843 for open surgery (p = 0.071). For single-level surgeries, 5 and 20% of patients undergoing MIS and open surgery, respectively, were discharged to inpatient rehabilitation. For 2-level surgeries, the rates were 13 and 29%, respectively.

CONCLUSIONS

While hospital setting, treatment population, patient selection, and physician expectation play major roles in determining hospital charges and LOS, this pilot study at an academic teaching hospital shows trends for quicker discharge, reduced hospital charges, and lower transfer rates to inpatient rehabilitation with MIS. However, larger multicenter studies are necessary to validate these findings and their relevance across diverse US practice environments.

Minimally invasive surgery for thoracolumbar spinal deformity: initial clinical experience with clinical and radiographic outcomes

Object

Adult degenerative scoliosis can be a cause of intractable pain, decreased mobility, and reduced quality of life. Surgical correction of this problem frequently leads to substantial clinical improvement, but advanced age, medical comorbidities, osteoporosis, and the rigidity of the spine result in high surgical complication rates. Minimally invasive surgery is being applied to this patient population in an effort to reduce the high complication rates associated with adult deformity surgery.

Methods

A retrospective study of 23 patients was undertaken to assess the clinical and radiographic results with minimally invasive surgery for adult thoracolumbar deformity surgery. All patients underwent a lateral interbody fusion followed by posterior percutaneous screw fixation and possible minimally invasive surgical transforaminal lumbar interbody fusion if fusion near the lumbosacral junction was necessary. A mean of 3.7 intersegmental levels were treated (range 2–7 levels). The mean follow-up was 13.4 months.

Results

The mean preoperative Cobb angle was 31.4°, and it was corrected to 11.5° at follow-up. The mean blood loss was 477 ml, and the operative time was 401 minutes. The mean visual analog scale score improvement for axial pain was 3.96. Clear evidence of fusion was seen on radiographs at 84 of 86 treated levels, with no interbody pseudarthroses. Complications included 2 returns to the operating room, one for CSF leakage and the other for hardware pullout. There were no wound infections, pneumonia, deep venous thrombosis, or new neurological deficits. However, of all patients, 30.4% experienced new thigh numbness, dysesthesias, pain, or weakness, and in one patient these new symptoms were persistent.

Conclusions

The minimally invasive surgical treatment of adult deformities is a promising method for reducing surgical morbidity. Numerous challenges exist, as the surgical technique does not yet allow for all correction maneuvers used in open surgery. However, as the techniques are advanced, the applicability of minimally invasive surgery for this population will likely be expanded and will afford the opportunity for reduced complications.

Early outcomes and safety of the minimally invasive, lateral retroperitoneal transpsoas approach for adult degenerative scoliosis

Object

The object of this study was to evaluate an alternative surgical approach to degenerative thoracolumbar deformity in adults. The authors present their early experience with the minimally invasive, lateral retroperitoneal transpsoas approach for placing interbody grafts and providing anterior column support for adult degenerative deformity.

Methods

The authors retrospectively reviewed a prospectively acquired database of all patients with adult thoracolumbar degenerative deformity treated with the minimally invasive, lateral retroperitoneal transpsoas approach at our institution. All patient data were recorded including demographics, preoperative evaluation, procedure used, postoperative follow-up, operative time, blood loss, length of hospital stay, and complications. The Oswestry Disability Index and visual analog scale (for pain) were also administered pre- and postoperatively as early outcome measures. All patients were scheduled for follow-up postoperatively at weeks 2, 6, 12, and 24, and at 1 year.

Results

The authors identified 25 patients with adult degenerative deformity who were treated using the minimally invasive, lateral retroperitoneal transpsoas approach. All patients underwent discectomy and lateral interbody graft placement for anterior column support and interbody fusion. The mean total blood loss was 53 ml per level. The average length of stay in the hospital was 6.2 days. Mean follow-up was 11 months (range 3–20 months). A mean improvement of 5.7 points on visual analog scale scores and 23.7% on the Oswestry Disability Index was observed. Perioperative complications include 1 patient with rhabdomyolysis requiring temporary hemodialysis, 1 patient with subsidence, and 1 patient with hardware failure. Three patients (12%) experienced transient postoperative anterior thigh numbness, ipsilateral to the side of approach. In this series, 20 patients (80%) were identified who had more than 6 months of follow-up and radiographic evidence of fusion. The minimally invasive, lateral retroperitoneal transpsoas approach, without the use of osteotomies, did not correct the sagittal balance in approximately one-third of the patients.

Conclusions

Degenerative scoliosis of the adult spine is secondary to asymmetrical degeneration of the discs. Surgical decompression and correction of the deformity can be performed from an anterior, posterior, or combined approach. These procedures are often associated with long operative times and a high incidence of complications. The authors' experience with the minimally invasive, lateral retroperitoneal transpsoas approach for placement of a large interbody graft for anterior column support, restoration of disc height, arthrodesis, and realignment is a feasible alternative to these procedures.