maximizing the potential of minimally invasive spine

ONVENTIONAL open surgeries have been widely usedfor decades in the treatment of various spinal dis-orders. Although conventional open spinal surgery

has been considered the standard for most spinal disorders,the clinical outcomes following open surgery can vary.Suboptimal clinical results often occur even after techni-cally successful open spine surgeries. Although contribut-ing factors to the suboptimal outcomes in those cases maybe related to poor patient selection, postsurgical scarring, oradjacent level disease, the significant soft tissue and mus-cle injuries that occur during exposure for open spine surg-eries may also be important contributing factors.

Minimally invasive spine surgery was developed todecrease the rate of approach-related morbidity associatedwith conventional open spine surgery in an effort to im-prove clinical outcomes.10,20,35,39 Based on that philosophy,various approaches and techniques have evolved to mini-mize the disruption of normal surrounding tissues. Al-though the approach and techniques can differ betweenopen spine surgery and MIS, the surgical goals are equiva-lent and should not be compromised in MISs.

Over the past several decades, MISs have been gainingmomentum and popularity in many surgical specialties,

including spine surgery. In 1991 Obenchain27 first reporteda case of laproscopic lumbar discectomy. Since that initialreport, MIS has become routinely used in the treatment ofdegenerative spine diseases, as in herniated disc removal,decompression of spinal stenosis, and fusions for degener-ative spinal disorders. Compared with those in convention-al open spine surgeries, the clinical outcomes of MISs haveindicated that the procedure is at least equally effective.Moreover, recovery time, pain, and the time required toreturn to work after surgery are reduced for MIS of thespine in several clinical series involving degenerativepathology.9,11,19 Although we have witnessed favorable pre-liminary clinical results in applying minimally invasivestrategies, long-term outcome studies supported by validat-ed outcome measuring instruments are pending. Moreover,it would be interesting to determine the impact of MIS onfusion rates, adjacent segment disease, and sustained painrelief. As spine surgeons become more experienced withthe techniques and technology associated with MIS, theindications for MIS continue to expand.12 Interestingly, thebenefit of decreasing approach-related morbidity might befar greater for more complex surgeries in spinal trauma,spinal deformity, and spinal oncology. In this report, wediscuss the techniques in, and the rationale for, using MISin these complex spinal disorders and provide illustrativecases for each.

Neurosurg. Focus / Volume 25 / August 2008

Neurosurg Focus 25 (2):E19, 2008

Maximizing the potential of minimally invasive spinesurgery in complex spinal disorders

PATRICK C. HSIEH, M.D.,1 TYLER R. KOSKI, M.D.,2 DANIEL M. SCIUBBA, M.D.,1

DAVE J. MOLLER, M.D.,2 BRIAN A. O’SHAUGHNESSY, M.D.,2 KHAN W. LI, M.D.,1

ZIYA L. GOKASLAN, M.D.,1 STEPHEN L. ONDRA, M.D.,2 RICHARD G. FESSLER, M.D.,2

AND JOHN C. LIU, M.D.2

1Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland;and 2Department of Neurological Surgery, Northwestern University Feinberg School of Medicine,Chicago, Illinois

Minimally invasive surgery (MIS) in the spine was primarily developed to reduce approach-related morbidity and toimprove clinical outcomes compared with those following conventional open spine surgery. Over the past severalyears, minimally invasive spinal procedures have gained recognition and their utilization has increased. In particular,MIS is now routinely used in the treatment of degenerative spine disorders and has been shown to be as effective asconventional open spine surgeries. Although the procedures are not yet widely recognized in the context of complexspine surgery, the true potential in minimizing approach-related morbidity is far greater in the treatment of complexspinal diseases such as spinal trauma, spinal deformities, and spinal oncology. Conventional open spine surgeries forcomplex spinal disorders are often associated with significant soft tissue disruption, blood loss, prolonged recoverytime, and postsurgical pain. In this article the authors review numerous cases of complex spine disorders managed withMIS techniques and discuss the current and future implications of these approaches for complex spinal pathologies.(DOI: 10.3171/FOC/2008/25/8/E19)

KEY WORDS • complex spine disorder • deformity • minimally invasive spine surgery •oncology • trauma

C

1

Abbreviations used in this paper: MIS = minimally invasivesurgery; SPO = Smith–Petersen osteotomy.

Unauthenticated | Downloaded 12/12/21 01:51 AM UTC

Spinal Trauma

More than 150,000 Americans annually suffer from trau-matic injuries to the spine.33 These injuries are often relat-ed to high-velocity and high-impact incidents such asmotor vehicle collisions or traumatic falls. Spinal cord in-juries, pain, and deformity can result from trauma to thespinal column. In addition, spinal injuries are often associ-ated with other musculoskeletal or visceral injuries basedon the mechanism of injury. Early surgical interventionscan prevent neurological deterioration or perhaps even re-verse neurological injury. Surgery can also improve painwhen bracing and other nonsurgical therapies fail, and itcan provide immediate spinal stability for unstable injuriesin a critically ill patient and prevent delayed spinal defor-mities.

Injuries to the cervical spine account for one-third of allspinal fractures and one-half to two-thirds of all spinal cordinjuries.18 In cervical spine injuries, the traditional Smith–Robinson anterolateral approach to the anterior spine is aprime example of an minimally invasive strategy. Althoughthis approach has been used to address pathology in theanterior cervical spine for . 50 years, it has not been wide-ly recognized as a minimally invasive tactic. Interestingly,however, the Smith–Robinson approach exemplifies theunderlying principle of MIS to minimize approach-relatedmorbidity. The procedure involves a direct route of dissec-tion through natural tissue planes to reach the spine withoutsignificant soft tissue or muscle injury. The Smith–Robin-son approach for anterior cervical spine surgery is widelyaccepted as one of the most successful and gratifying pro-cedures in spine surgery. One reason for its success is thelimited approach-related soft tissue and muscle injuriesfrom surgical exposure. For posterior cervical spine in-juries, both decompression and instrumented fusions canbe performed via a muscle-splitting approach with mini-

mal-access retractors.9,13,36,43,44,47 As is the case for degener-ative cervical disease, central and foraminal decompressionand instrumented fusion can be performed via minimallyinvasive approaches for cervical spine injuries.

Of all spine injuries, 30% involve the thoracic spine and42.5% the lumbosacral spine.18 Thoracolumbar injuries areoften associated with high-impact and high-velocity trau-mas. Injury to the thoracolumbar spine can range fromcompression fractures and burst fractures to flexion dis-traction injuries with fracture dislocation. Various classifi-cation systems have been formulated to stratify thora-columbar spine injuries in an attempt both to offer amechanically sound description of the insult and to providea framework for treatment.5,6,24,41,42 In general, stable frac-tures are treated with medical observation and bracing,whereas unstable fractures are treated with operative inter-ventions.

Open surgical treatments with anterior, posterior, orcombined approaches have been widely used for thora-columbar spine injuries over the years. Although these the-rapeutic approaches are successful in providing neural de-compression and stabilization, they are associated withprolonged surgical time, significant blood loss, increasedinfection rate, and significant approach-related soft tissueand muscle destruction. In addition, patients are often af-flicted with significant pain despite successful surgicalrecovery.

In an effort to improve clinical outcomes, several mini-mally invasive approaches and techniques have been de-veloped to minimize approach-related morbidity. The mostcommon application of MIS for thoracolumbar injuriesis in percutaneous cement augmentation by vertebroplastyor kyphoplasty of compression fractures and burst frac-tures.30–32 These percutaneous interventions have beenshown to be highly effective in improving spinal stabilityfrom vertebral insufficiency and pain relief. Moreover,

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2 Neurosurg. Focus / Volume 25 / August 2008

FIG. 1. Case 1. Left: Sagittal CT scan demonstrating a flexion distraction injury at the T-11 level. Right: Axial CTscan obtained through the fracture site, revealing that there is no central canal compromise.


kyphoplasty has been shown to improve spinal deformityby the restoration of vertebral body height.32 In addition topercutaneous cement augmentation, percutaneous instru-mentation with or without fusion is now being performedfor spinal stabilization following thoracolumbar in-juries.33,34,37 Compared with conventional open spine surg-eries, percutaneous instrumentation procedures are associ-ated with minimal soft tissue disruption, decreased bloodloss, reduced infection rate, and less operative time in mostcases. Particularly in patients with polytrauma or thosewith significant medical comorbidities, complex openspine surgery may not be possible. Unlike open surgery,percutaneous instrumentation is an alternative that can pro-vide spinal stabilization of thoracolumbar injuries with adecreased perioperative morbidity rate.

Illustrative Cases

Case 1. This 87-year-old man with ankylosing spondyli-tis and multiple medical comorbidities fell while at homeand presented to our institution with severe back pain andlower-extremity weakness. A CT scan demonstrated a high-ly unstable flexion distraction injury (AO Type C injury) atT-11 without spinal canal compromise (Fig. 1). An openmultilevel instrumented thoracolumbar fusion was initiallyrecommended to the patient; however, during the preopera-tive medical clearance, the perioperative morbidity andmortality risks associated with a prolonged and extensivesurgical intervention was considered by the medical serviceto be too great. Given the highly unstable T-11 fracture sur-gical intervention was required, and percutaneous instru-mented fusion of T-9 to L-1 was recommended and per-formed without arthrodesis, without complication. Becausethe patient had preexisting ankylosis of the spine fromankylosing spondylitis, arthrodesis was felt to be unneces-sary and thus not performed. The surgery was completed in2 hours and 53 minutes, and the total blood loss for this pro-

cedure was 150 ml. Spinal fracture reduction and stabiliza-tion was achieved following the percutaneous instrumenta-tion (Fig. 2). Postoperatively, the patient did not require anyblood transfusions or fluid resuscitation. He was able to par-ticipate in physical therapy, and he was transferred to arehabilitation facility after the hospitalization.

Case 2. This 18-year-old man suffered an L-5 burst frac-ture after skydiving (Fig. 3). He was initially treated withorthotic bracing; however, increasing back pain subse-quently developed together with a foot drop. Surgical de-compression and stabilization of the fracture was offered tothe patient. An L-5 anterior vertebrectomy was also dis-cussed, and minimally invasive decompression and pediclescrew fixation of L4–S1 were also offered to allow healingof the L-5 body fracture. The patient underwent a mini-mally invasive L-5 laminectomy and L4–S1 percutaneousinstrumentation placement without any complications (Fig.4). Given the goal of instrumentation removal after healingof the L-5 vertebral body fracture, arthrodesis was not per-formed in this case. The patient had an uncomplicated post-surgical recovery, and he was discharged home 3 days aftersurgery with significant pain and neurological improve-ment. Three months after surgery, a CT scan demonstratedhealing of the L-5 vertebral fracture, and thus the percuta-neous instrumentation was subsequently removed. Flexionand extension radiographs obtained following instrumenta-tion removal revealed a normal range of motion in the lum-bosacral spine (Fig. 5). Six years after the initial surgery,the patient was still extremely satisfied with the operation.He is without any significant lower-back pain and requiresno routine analgesics.

Cases Review. These illustrative cases demonstrate thatMIS can be applied to traumatic spine injuries and lead tooperative goals identical to those sought in conventionalopen surgeries. In both patients, spinal fixation was ach-ieved with percutaneous instrumentation. In our experi-


Minimally invasive surgery for complex spinal disorders

3

FIG. 2. Case 1. Left: Lateral radiograph demonstrating percutanous placement of pedicle screws and rod.Right: Anteroposterior radiograph showing the percutaneous pedicle screw instrumentation construct.


ence, percutaneous instrumentation and minimally invasivedecompression, compared with open surgeries, lead to asubstantial reduction in the infection rate, blood loss, thetransfusion rate, and cardiopulmonary complications fromfluid resuscitation. These advantages are particularly valu-able in patients with medical comorbidities or those withmultiorgan traumas who are at risk for significant medicalcomplications perioperatively.

In contrast, a potential disadvantage of MIS feared byspine surgeons is the inability to perform adequate arthro-desis and achieve long-term osseous fusion. In actuality,excellent arthrodesis can be successfully achieved throughMIS by facet joint arthrodesis or interbody arthrodesis.Moreover, our illustrative cases revealed that the biologicalmilieu of the patient has a significant impact. In patientswith ankylosing spondylitis, as in the patient in Case 1,ankylosis is likely to ensue with spinal stabilization andapposition of the fracture sites. With ankylosis of the spinefrom ankylosing spondylitis and subsequent healing of theT-11 fracture, instrumentation removal was unnecessary inour patient. In addition, the removal of percutaneous instru-mentation is challenging with current minimally invasivetechniques. In the patient in Case 2, the L-5 fractured bodywas allowed to heal with internal fixation. With the healedvertebral body a posterior fusion was unnecessary, and in-strumentation could be removed subsequently to salvagespinal mobility across the previously fractured level. Thisscenario is far more desirable in a young individual com-pared with a fusion across the lumbosacral junction.

Spinal Deformity

Spinal deformity with imbalance of coronal and sagittalalignment of the spine from various causes can result inneurological compromise, poor cosmesis, and pain. Thesefactors can impart significant debilitation of psychosocialand functional well-being.2 In cases of severe spinal defor-mity, patients can suffer considerable physiological com-promise, including a decline in cardiopulmonary capacity.Surgical treatment for spinal deformity is indicated inpatients with severe kyphoscoliosis, rapid curve progres-sion, severe pain, or poor cosmesis.

Dating back to the early 20th century, traditional surgicaltreatment for spinal deformity involves long-segment

P. C. Hsieh et al.


FIG. 3. Case 2. Axial CT scan demonstrating the L-5 burst frac-ture with bone fragment retropulsion into the canal and encroach-ment of the spinal canal and lateral recess.

FIG. 4. Case 2. Left: Axial CT scan revealing spinal canal and lateral recess decompression following minimallyinvasive laminectomy. Right: Sagittal CT scan demonstrating no significant residual retropulsion of the L-5 burst frac-ture and acceptable sagittal alignment following percutaneous instrumentation,.


spinal fusions. Surgeries for the correction of a spinal de-formity are time-consuming and technically demanding. Inaddition, these surgeries are often associated with a highperioperative morbidity rate. The overall complication ratein adult patients undergoing spinal deformity surgeryranges from 40 to 86%, and major morbidities occur in ~

20% of cases.1,4,22 Other than neurological injury, majorcomplications include infection, myocardial infarction, car-diac failure, pulmonary embolism, acute respiratory dis-tress syndrome, transfusion-related lung injury, renal fail-ure, and even death. Patients older than 60 years withmedical comorbidities have a particularly increased risk.4

It has been projected that adults 55–64-years-old are thefastest growing segment of our population. As the elderlypopulation expands over the next decade, there will be anincreasing number of patients presenting with degenerativespine diseases and adult degenerative scoliosis. Morepatients will seek surgical treatment to improve pain symp-toms and quality of life. Most of the elderly patients willhave medical comorbidities and an increased risk of peri-operative complications; therefore, any intervention thatcan reduce the perioperative morbidity associated withspinal deformity surgery in the elderly may have a signifi-cant impact on clinical outcomes and reduce healthcarecosts.

The first attempt to utilize minimally invasive proce-dures in spinal deformity surgery occurred in 1993 with theuse of endoscopic techniques in thoracic spine surgery.23

Thoracoscope-assisted procedures for spinal deformity areperformed for anterior releases to increase both the flexi-bility of the spine and the fusion surface area with anteriorintervertebral fusions.25,26,40 Advantages of thoracoscopicsurgery for spinal deformity include decreased surgicaltrauma, scarring, postoperative pain, and perioperativemorbidity. In addition, compared with posterior approach-es, anterior procedures in spinal deformity surgeries can re-duce the number of fusion segments required to achievecurve correction.26

Over the past several years, minimal-access lateral ap-proaches to the lumbar spine have been developed for lum-bar interbody fusion.8,28,38 Through small flank incisionsand by using the retroperitoneal approach, anterior lumbardisectomy and interbody fusion can be performed from



5

FIG. 5. Case 2. Lateral flexion (left) and extension (right) radiographs demonstrating normal excursion of the lum-bosacral spine without spinal instability.

FIG. 6. Case 3. Long-cassette posteroanterior (left) and lateral(right) radiographs showing the preoperative coronal and sagittalalignment, respectively.


L1–2 down to L4–5 through minimal-access retractors.With variation in the approaches, direct access to the thora-columbar segments and even the thoracic spine can be per-formed safely and with ease. These lateral approaches areparticularly useful in the treatment of lumbar or thoraco-lumbar curves that are associated with adult degenerativescoliosis. They allow anterior releases to increase the flex-ibility of the spine in patients with rigid curves, and theyallow placement of large intervertebral grafts to increasethe fusion surface area. Strategically placed interbody graftscan result in substantial sagittal and coronal corrections.Furthermore, similar to the experience with thoracoscope-assisted surgeries, anterior releases and correction of curvesvia minimally invasive lateral approaches in the lumbarspine can result in a decreased number of fusion levels.

Minimally invasive techniques can be applied in spinaldeformity surgery via posterior approaches as well as theanterior approaches. Percutaneous instrumentation can beapplied for additional segmental stabilization followinganterior releases and intervertebral fusions. Moreover,SPOs can be performed through minimal-access retractorswith decreased disruption of normal soft tissues. With thelatest percutaneous instrumentation technologies, safe clo-sure of osteotomies can be performed to increase segmen-tal lordosis and to allow apposition of osseous surfaces forsubsequent fusion.

Illustrative Case

Case 3. This 61-year-old woman with a history of ado-lescent idiopathic scoliosis had been monitored for herspinal deformity for many years (Fig. 6). Over the last fewyears, she experienced late progression of the adolescentidiopathic scoliosis (Lenke Curve Type 5) with increasingpain and deformity. After nonsurgical management of hersymptoms failed, surgical correction of the deformity andinstrumented fusion of the spine were recommended. A 2-stage minimally invasive approach was then applied. In thefirst stage, she underwent the placement of percutaneousinstrumentation from T10–L3 in conjunction with SPOs atT11–12, T12–L1, and L1–2 through a minimal accesstubular retractor. Posterior deformity correction was per-formed using segmental instrumentation after the SPOreleases. To provide anterior support and fusion, the secondstage of the procedure was performed 8 days after the firststage. Direct lateral discectomies and interbody arthrodesiswith cage placement were performed through minimal-access retractors at T12–L1, L1–2, and L2–3. The totaloperative time was 8 hours for the first-stage procedure and5 hours for the second. Estimated blood loss in the patientwas 1 L over both procedures, and the patient received only2 units of transfused blood during both perioperative peri-ods. Postoperative standing long-cassette radiographsdemonstrated balanced coronal and sagittal alignment (Fig.7). The patient had an uncomplicated recovery, and she wasdischarged from the hospital 11 days following the first-stage procedure.

Case Review. Over recent years, minimally invasivesurgical approaches, techniques, and technologies haveevolved to allow spinal deformity surgeons to accomplishtraditional goals through smaller incisions, with limitednormal tissue disruption and minimal-access retractors.Our illustrative case reveals that deformity correction andstabilization of the spine while preserving coronal andsagittal balance are possible with MISs. In degenerativedisease, MIS has been shown to decrease blood loss, thehospitalization stay, and the postoperative recovery period.Minimally invasive surgery in spinal deformity is still in itsinfancy and experience with the procedure is too limited todraw generalized conclusions; however, our early experi-ence with minimally invasive procedures in spinal defor-mity has been associated with decreased perioperativeblood loss and need for transfusions. The reduced bloodloss will decrease the cardiopulmonary morbidity that typ-ically follows aggressive fluid resuscitation. Moreover, thedecreased transfusion rate will reduce the likelihood oftransfusion-related lung injuries, which has become themost common cause of death after blood transfusion.1,45,46

Additional clinical experience with minimally invasiveprocedures in spinal deformity will determine if these fac-tors can truly decrease major perioperative complicationrates in the elderly and improve their clinical outcomes.

Spinal Oncology

Currently, . 1.4 million new cases of cancer are diag-nosed annually in the U.S., with ~ 500,000 patients in thesecases dying annually from metastatic disease. Althoughprimary tumors of the spine are not common, improve-

P. C. Hsieh et al.


FIG. 7. Case 3. Long-cas-sette posteroanterior (left) andlateral (right) radiographsrevealing postoperativeimprovement of the thora-columbar curve with mainte-nance of coronal and sagittalbalance.


ments in the treatment of systemic cancer combined withadvancements in imaging technology will likely result inan increasing incidence of spine metastases. Symptomaticlesions may contribute to substantial pain and neurologicaldysfunction in a large proportion of patients, and thussound treatment of spinal metastases is especially relevant.

In general, the treatment of metastatic lesions in the spineis considered palliative at best, with survival chiefly affect-ed by the extent and control of systemic disease. Nonethe-less, the management of metastatic spinal lesions can dras-tically improve quality of life, especially as it pertains todebilitating pain and loss of ambulatory ability. Althoughthe treatment of these tumors has involved radiation thera-py as the primary modality, surgical intervention has be-come an essential component of care. In a recent prospec-tive randomized trial Patchel et al.29 showed that surgicaldecompression plus radiation therapy was superior to radi-ation therapy alone in the treatment of metastatic epiduralspinal cord compression with regard to neurological func-tion. Surgeries performed in that study involved direct de-compressive procedures with spinal reconstruction. Al-though these procedures were not minimally invasive, theapplication of techniques less destructive to the paraspinalsoft tissues would likely provide similar results if the goalsof decompression and stabilization were equally met.

Patients with systemic cancer face a greater likelihood ofsurgical complications and postoperative morbidity.3,7,21 Forinstance, it has been shown repeatedly in the literature that

the resection of a spine tumor is associated with more post-operative surgical site infections than spine operations forother indications.3 Factors likely contributing to such peri-operative morbidity include lower preoperative functionalstatus, poorer nutrition, immunosuppression, chronic ste-roid use, and in some cases previous radiation to the site ofsurgery. Thus, for cases in which surgery is being consid-ered, large tissue dissection can lead to increased woundcomplications. Minimally invasive spine surgeries throughsmaller incisions can mitigate such wound complicationsby limiting collateral damage to surrounding soft tissuesduring exposure and instrumentation.

One of the first minimally invasive techniques used totreat spine tumors was percutaneous placement of poly-methylmethacrylate cement. With fluoroscopic guidance,this cement can be placed percutaneously to fill the verte-bral body directly (vertebroplasty) or after kyphosis hasbeen reduced via internal expansion of a balloon device(kyphoplasty).14,15 The application of cement often providesimmediate pain relief, likely as a result of the stabilizationof fractures and reduction in micromobility, but also possi-bly due to thermal damage to small pain fibers resultingfrom the exothermic reaction involved during cement cur-ing. Regardless, although such treatment can provide ex-cellent and immediate pain relief via a noninvasive percu-taneous approach, it does nothing to treat the localoncological disease.

Hence, cement augmentation techniques are often com-



7

FIG. 8. Case 4. Left: Preoperative sagittal T2-weighted MR image demonstrating metastatic spine tumor involve-ment of the T-4 and T-5 vertebral bodies. There are pathological fractures of the vertebral bodies with retropulsion ofbone into the spinal canal. Right: Preoperative axial T2-weighted MR image at the T-5 level revealing severe spinalcord compression and loss of cerebrospinal fluid space around the cord.


bined with radiation therapy.16 Classically, such treatmentinvolves the standard delivery of ionizing radiation to thediseased spinal segment and to 2 segments above andbelow the index level. In cases of local tumor recurrence,however, such radiation therapy cannot be repeated be-cause of the potentially supratherapeutic dosage of radia-tion directed at the spinal cord and neighboring tissues.Therefore, radiation that can be delivered in a focal mannerhas been used more recently to overcome this problem.Such techniques, commonly referred to as “radiosurgery”or “image-modulated radiation therapy,” are used to deliv-er multiple doses of radiation to the lesion, with each doserepresenting only a small proportion of the total dose. Bychanging the trajectory through normal tissue during eachexposure (radiosurgery) or by carefully collimating the ra-diation so that there is a steep decline in radiation intensityaround the lesion (image-modulated radiation therapy),larger doses of ionizing energy can be delivered to the path-ological segment while minimizing damage to surroundingnonneoplastic tissues. Such techniques thus allow treat-ment of recurrent spine lesions and tumors usually consid-ered radiation insensitive.17

Although both percutaneous vertebroplasty/kyphoplastyand radiosurgery are effective in addressing pain or localdisease control, they do not address the spinal instabilityand deformity resulting from metastatic tumor involve-ment. The evolution of MIS for spinal tumors in recentyears has involved direct removal of the lesion with instru-mented fixation of the spine. Through minimal-access tu-bular retractors placed at the diseased levels, direct tumorresection and spinal cord decompression can be performedwith limited soft tissue and muscle dissection. Moreover,stabilization can be achieved in a similar minimally inva-

sive manner by using simultaneous percutaneous instru-mentation with cement reconstruction and/or placement ofan intervertebral structural graft.

Illustrative Case

Case 4. This 39-year-old man with a 6-month history ofback pain presented to an outside hospital with increasingback pain associated with lower-extremity paresthesia.During a medical workup, the patient was found to have T-4 and -5 vertebral fractures and a right lung mass on radi-ography. A biopsy specimen of the lung mass indicated pri-mary lung adenocarcinoma. Computed tomography andMR imaging of his spine demonstrated pathological frac-tures of T4 and -5 vertebral bodies from metastasis withsignificant epidural disease (Fig. 8). The patient also hadintermittent paresthesia and mild lower-extremity weak-ness of 4+/5 in strength. He was offered a minimally inva-sive laminectomy and vertebrectomy of T4–5 for decom-pression with an instrumented fusion of the thoracic spineinvolving T1–8. After obtaining informed consent, thepatient underwent percutaneous instrumented fusion ofT1–8 with laminectomy and costotransversectomy for ver-tebrectomy of the T-4 and -5 metastatic tumor throughbilateral expandable minimal-access retractors (Fig. 9). Anintervertebral distractible cage was placed through the min-imal-access retractor for reconstruction of the T4–5 anteri-or and middle columns following vertebrectomy. Thepatient tolerated the procedure well without complications.The total operative time was ~ 7 hours, and the total esti-mated blood loss was 1.2 L. The patient had preoperativeanemia, and he subsequently required 2 units of transfusedblood during the perioperative period. A postoperative CT

P. C. Hsieh et al.


FIG. 9. Case 4. Intraoperative photograph showing the 2-level vertebrectomy performed through minimal-accessretractors along with simultaneous percutaneous instrumented fusion.


demonstrated circumferential decompression of the diseaseat T-4 and -5 with circumferential instrumented reconstruc-tion of the spine (Fig. 10). The patient had an uncomplicat-ed postoperative course, and he was discharged from thehospital 5 days after his surgery.

Case Review. In the surgical treatment of patients withmetastatic spine tumors, the theoretical limitation of os-seous fusion with MIS is insignificant. Patients with symp-tomatic metastatic spine tumors generally have an averagelifespan of ~ 6–12 months. Treatment goals in these pa-tients are the preservation of neurological function, stabi-lization of the spine, and improvement in pain. Generally,decompression and instrumentation without arthrodesis aresufficient to achieve these goals in most of these patients.Furthermore, almost all of these patients will receive ste-roids and chemotherapy and undergo radiation treatment.Therefore, even the most meticulous arthrodesis techniquesmay not result in osseous fusion in long-term survivors.

In our illustrative case, a 2-level thoracic laminectomyand vertebrectomy for a symptomatic metastatic spinaltumor was performed with successful decompression of thespinal cord through bilateral minimal-access retractors.Final instrumented reconstruction and stabilization of thespinal column was performed with the placement of a dis-tractable cage through the minimal-access retractor and theplacement of percutaneous pedicle screw instrumentation.In the patient in this case, circumferential decompressionand reconstruction of the spinal column was completedsuccessfully without complications. In our early experi-ence, compared with the open procedures, MIS of the spinefor these cases resulted in decreased blood loss and fasterrecovery in the subacute recovery phase at ~ 2–4 weeks fol-lowing surgery. Furthermore, the smaller incisions and lim-ited soft tissue disruption led to a reduction in the infectionrate and wound complications. Overall, a wide variety ofMIS options are now available for the treatment of patients

with metastatic spine tumors. Combinations of the variousMIS options with medical therapies, such as chemotherapyand radiation therapy, will likely continue to improve ourability to treat patients with cancer.

Conclusions

As spine surgeons become more experienced and facilewith MIS techniques and procedures, the application ofthese strategies for complex spinal disorders will continueto increase. Currently, advancements in surgical technolo-gy and techniques as well as early clinical results have dri-ven surgeons to expand the use of MIS in the spine. Never-theless, prospective and long-term clinical studies areneeded to demonstrate the true clinical benefits. Althoughthe case illustrations herein were presented to outline thegreat potential of using MIS in severe spinal pathologies,future prospective studies on outcomes following openspine surgery vs. MISs for such disorders will likely dem-onstrate the tangible benefits of the different approaches.

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Manuscript submitted May 15, 2008.Accepted May 30, 2008.Address correspondence to: Patrick C. Hsieh, M.D., Department

of Neurological Surgery, University of Southern California, KeckSchool of Medicine, 1520 San Pablo Street, #3800, Los Angeles,California 90033. email: [email protected].

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