The Accuracy of Patient-Specific Spinal Drill Guides Is Non-Inferior to Computer-Assisted Surgery: The Results of a Split-Spine Randomized Controlled Trial

In recent years, patient-specific spinal drill guides (3DPGs) have gained widespread popularity. Several studies have shown that the accuracy of screw insertion with these guides is superior to that obtained using the freehand insertion technique, but there are no studies that make a comparison with computer-assisted surgery (CAS). The aim of this study was to determine whether the accuracy of insertion of spinal screws using 3DPGs is non-inferior to insertion via CAS. A randomized controlled split-spine study was performed in which 3DPG and CAS were randomly assigned to the left or right sides of the spines of patients undergoing fixation surgery. The 3D measured accuracy of screw insertion was the primary study outcome parameter. Sixty screws inserted in 10 patients who completed the study protocol were used for the non-inferiority analysis. The non-inferiority of 3DPG was demonstrated for entry-point accuracy, as the upper margin of the 95% CI (−1.01 mm−0.49 mm) for the difference between the means did not cross the predetermined non-inferiority margin of 1 mm (p < 0.05). We also demonstrated non-inferiority of 3D angular accuracy (p < 0.05), with a 95% CI for the true difference of −2.30°−1.35°, not crossing the predetermined non-inferiority margin of 3° (p < 0.05). The results of this randomized controlled trial (RCT) showed that 3DPGs provide a non-inferior alternative to CAS in terms of screw insertion accuracy and have considerable potential as a navigational technique in spinal fixation.

Accuracy of Patient-Specific 3D-Printed Drill Guides for Pedicle and Lateral Mass Screw Insertion: An Analysis of 76 Cervical and Thoracic Screw Trajectories

STUDY DESIGN

Single-center retrospective case series.

OBJECTIVE

The purpose of this study was to assess the safety and accuracy of three-dimensional (3D)-printed individualized drill guides for pedicle and lateral mass screw insertion in the cervical and upper-thoracic region, by comparing the preoperative 3D surgical plan with the postoperative results.

SUMMARY OF BACKGROUND DATA

Posterior spinal fusion surgery can provide rigid intervertebral fixation but screw misplacement involves a high risk of neurovascular injury. However, modern spine surgeons now have tools such as virtual surgical planning and 3D-printed drill guides to facilitate spinal screw insertion.

METHODS

A total of 15 patients who underwent posterior spinal fusion surgery involving patient-specific 3D-printed drill guides were included in this study. After segmentation of bone and screws, the postoperative models were superimposed onto the preoperative surgical plan. The accuracy of the realized screw trajectories was quantified by measuring the entry point and angular deviation.

RESULTS

The 3D deviation analysis showed that the entry point and angular deviation over all 76 screw trajectories were 1.40 ± 0.81 mm and 6.70 ± 3.77°, respectively. Angular deviation was significantly higher in the sagittal plane than in the axial plane (P = 0.02). All screw positions were classified as "safe" (100%), showing no neurovascular injury, facet joint violation, or violation of the pedicle wall.

CONCLUSIONS

3D virtual planning and 3D-printed patient-specific drill guides appear to be safe and accurate for pedicle and lateral mass screw insertion in the cervical and upper-thoracic spine. The quantitative 3D deviation analyses confirmed that screw positions were accurate with respect to the 3D-surgical plan.Level of Evidence: 4.

Cervical spondylodiscitis following cricopharyngeal botulinium toxin injection

BACKGROUND

Iatrogenic cervical spondylodiscitis is rare, but may occur after various medical interventions.

METHODS

We report a case of a diabetic 70-years-old female with C5-C6 spondylodiscitis and symptomatic epidural abscess with neck pain and upper limb paresis after endoscopic botulinum toxin injection for the treatment of dysphagia. Treatment included antibiotic therapy with amoxicillin and later on benzylpenicillin for the next ten weeks and corporectomy with spondylodesis.

RESULT

The patient made an excellent recovery, with complete resolution of paresis and only minor residual hypoesthesia at one year after operation.

CONCLUSION

Cervical spondylodiscitis should be considered early, in patients with neck pain after endoscopic cricopharyngeal injection, as timely diagnosis and treatment can prevent serious and irreversible neurological deficit.

Accuracy Assessment of Pedicle and Lateral Mass Screw Insertion Assisted by Customized 3D-Printed Drill Guides: A Human Cadaver Study

BACKGROUND

Accurate cervical screw insertion is of paramount importance considering the risk of damage to adjacent vital structures. Recent research in 3-dimensional (3D) technology describes the advantage of patient-specific drill guides for accurate screw positioning, but consensus about the optimal guide design and the accuracy is lacking.

OBJECTIVE

To find the optimal design and to evaluate the accuracy of individualized 3D-printed drill guides for lateral mass and pedicle screw placement in the cervical and upper thoracic spine.

METHODS

Five Thiel-embalmed human cadavers were used for individualized drill-guide planning of 86 screw trajectories in the cervical and upper thoracic spine. Using 3D bone models reconstructed from acquired computed tomography scans, the drill guides were produced for both pedicle and lateral mass screw trajectories. During the study, the initial minimalistic design was refined, resulting in the advanced guide design. Screw trajectories were drilled and the realized trajectories were compared to the planned trajectories using 3D deviation analysis.

RESULTS

The overall entry point and 3D angular accuracy were 0.76 ± 0.52 mm and 3.22 ± 2.34°, respectively. Average measurements for the minimalistic guides were 1.20 mm for entry points, 5.61° for the 3D angulation, 2.38° for the 2D axial angulation, and 4.80° for the 2D sagittal angulation. For the advanced guides, the respective measurements were 0.66 mm, 2.72°, 1.26°, and 2.12°, respectively.

CONCLUSION

The study ultimately resulted in an advanced guide design including caudally positioned hooks, crosslink support structure, and metal inlays. The novel advanced drill guide design yields excellent drilling accuracy.

Prediction of Quality of Life and Survival After Surgery for Symptomatic Spinal Metastases: A Multicenter Cohort Study to Determine Suitability for Surgical Treatment

BACKGROUND

Surgery for symptomatic spinal metastases aims to improve quality of life, pain, function, and stability. Complications in the postoperative period are not uncommon; therefore, it is important to select appropriate patients who are likely to benefit the greatest from surgery. Previous studies have focused on predicting survival rather than quality of life after surgery.

OBJECTIVE

To determine preoperative patient characteristics that predict postoperative quality of life and survival in patients who undergo surgery for spinal metastases.

METHODS

In a prospective cohort study of 922 patients with spinal metastases who underwent surgery, we performed preoperative and postoperative assessment of EuroQol EQ-5D quality of life, visual analog score for pain, Karnofsky physical functioning score, complication rates, and survival.

RESULTS

The primary tumor type, number of spinal metastases, and presence of visceral metastases were independent predictors of survival. Predictors of quality of life after surgery included preoperative EQ-5D (P = .002), Frankel score (P < .001), and Karnofsky Performance Status (P < .001).

CONCLUSION

Data from the largest prospective surgical series of patients with symptomatic spinal metastases revealed that tumor type, the number of spinal metastases, and the presence of visceral metastases are the most useful predictors of survival and that quality of life is best predicted by preoperative Karnofsky, Frankel, and EQ-5D scores. The Karnofsky score predicts quality of life and survival and is easy to determine at the bedside, unlike the EQ-5D index. Karnofsky score, tumor type, and spinal and visceral metastases should be considered the 4 most important prognostic variables that influence patient management.

Surgery on spinal epidural metastases (SEM) in renal cell carcinoma: a plea for a new paradigm

BACKGROUND CONTEXT

Prediction models for outcome of decompressive surgical resection of spinal epidural metastases (SEM) have in common that they have been developed for all types of SEM, irrespective of the type of primary tumor. It is our experience in clinical practice, however, that these models often fail to accurately predict outcome in the individual patient.

PURPOSE

To investigate whether decision making could be optimized by applying tumor-specific prediction models. For the proof of concept, we analyzed patients with SEM from renal cell carcinoma that we have operated on.

STUDY DESIGN/SETTING

Retrospective chart analysis 2006 to 2012.

PATIENT SAMPLE

Twenty-one consecutive patients with symptomatic SEM of renal cell carcinoma.

OUTCOME MEASURES

Predictive factors for survival.

METHODS

Next to established predictive factors for survival, we analyzed the predictive value of the Motzer criteria in these patients. The Motzer criteria comprise a specific and validated risk model for survival in patients with renal cell carcinoma.

RESULTS

After multivariable analysis, only Motzer intermediate (hazard ratio [HR] 17.4, 95% confidence interval [CI] 1.82-166, p=.01) and high risk (HR 39.3, 95% CI 3.10-499, p=.005) turned out to be significantly associated with survival in patients with renal cell carcinoma that we have operated on.

CONCLUSIONS

In this study, we have demonstrated that decision making could have been optimized by implementing the Motzer criteria next to established prediction models. We, therefore, suggest that in future, in patients with SEM from renal cell carcinoma, the Motzer criteria are also taken into account.

Unexpected symptoms after rhTSH administration due to occult thyroid carcinoma metastasis

¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸FDG-PET) scintigraphy is a useful imaging technique in the evaluation of metastasised thyroid carcinoma. Administration of recombinant human thyrotropin (rhTSH, Thyrogen®) increases the diagnostic yield of this procedure. Here we present a 64-year-old male who was followed for Hürthle cell carcinoma of the thyroid with several intrapulmonary metastases. He developed sudden complaints of neck pain following rhTSH administration as part of the routine preparation for a diagnostic ¹⁸FDG-PET÷CT procedure. This investigation subsequently revealed a previously undetected metastatic lesion in the first cervical vertebra, with no signs of spinal cord compression. Treatment with a nonsteroidal anti-inflammatory drug reduced the symptoms sufficiently, and a few weeks later the neurosurgeon performed a complete resection of the metastasis. It is likely that the symptoms were caused by oedema and÷or increased blood flow to the lesion. Physicians should be aware that rhTSH administration to patients with disseminated thyroid carcinoma may lead to sudden onset of symptoms caused by previously occult metastases.

Clinimetric properties of the EuroQol-5D in patients with chronic low back pain

BACKGROUND CONTEXT

Clinimetric properties of the EuroQol-5D (EQ-5D) in patients with nonspecific chronic low back pain (CLBP) are largely unknown.

PURPOSE

To study the criterion validity, responsiveness, and minimal clinically important change (MCIC) of EQ-5D in patients with CLBP.

STUDY DESIGN

Prospective study design carried out in a multispecialist Spine Center in The Netherlands.

PATIENT SAMPLE

One hundred fifty-one patients with CLBP.

OUTCOME MEASURES

Quality of life (QOL) was measured with EQ-5D, consisting of two scales: one scale measuring QOL with five categorical questions and the other measuring health state on a visual analog scale (0-100). Criterion measures were disability, measured with the Pain Disability Index (PDI) and the Roland Morris Disability Questionnaire (RMDQ), and pain intensity, measured with a numeric rating scale (NRS).

METHODS

Pearson correlation coefficients between the EQ-5D and RMDQ, PDI, and NRS were calculated to test the criterion validity. Correlations were interpreted based on predefined criteria. Responsiveness of the EQ-5D was calculated with area under the receiver operating characteristics (ROC) curve. Minimal clinically important change was calculated with the optimal cutoff point under the ROC curve, and sensitivity and specificity were also calculated.

RESULTS

Correlations between EQ-5D and criterion measures ranged between 0.39 and 0.59 and were considered moderate to good. Areas under the ROC curve ranged from 0.59 to 0.72 depending on the external criterion and EQ-5D subscale. The MCIC was 0.03 points for the categorical scales of the EQ-5D and 10.5 points for the EQ-5D visual analog scale.

CONCLUSIONS

The EQ-5D is a valid and responsive QOL scale in patients with CLBP.

Posterior transdural discectomy: a new approach for the removal of a central thoracic disc herniation

BACKGROUND

The optimal surgical approach for thoracic disc herniation remains a matter of debate, especially for central disc herniation. In this paper, we present a new technique to remove central thoracic disc herniation, the posterior transdural approach, and report a series of 13 cases operated on in this way at our institute.

METHODS

Between September 2004 and October 2010, 13 patients with symptomatic central thoracic disc herniation were operated on, utilising this posterior transdural approach. All patients underwent magnetic resonance imaging (MRI) of the thoracic spine before surgery. All patients were followed at our outpatient department for at least 3 months. In addition, all patients were interviewed in April 2009 and February 2011 to evaluate the final results. A seven-point Likert scale was applied and the Frankel score was determined preoperatively and postoperatively. Additionally, a postoperative MRI was obtained for all but two patients.

RESULTS

The most frequently involved levels were T10-11 and T12-L1. Median operative time was 210 min (range 140-360). Three patients experienced reversible complications. No patient required spinal fixation. The median duration of hospitalisation was 6 days (range 4-20 days). With a median follow-up of 18 months, symptoms improved in 12 patients (92%), including the three patients with complications. One patient was unchanged (8%), while none of the patients experienced worsening of symptoms.

CONCLUSIONS

The posterior transdural approach is well tolerated by the patient and has a relatively high success rate. It is a relatively simple and safe procedure, suitable for the operative treatment of almost all types of thoracic disc herniation, but especially the centrally located disc herniation.

Cervical cystic swelling in an adolescent: unusual association of a cervical mature teratoma with vertebral anomalies and a history of gastric duplication cyst

A 14-year-old girl presented with a cervical cystic swelling in association with deformity of cervical vertebrae. As a child, she had been treated for gastric duplication. Pathologic examination of the resected cervical swelling revealed a mature teratoma. We discuss possible embryologic associations, which could explain the unusual combination of a mature teratoma with vertebral anomalies and gastric duplication.

Cauda equina entrapment in a pseudomeningocele after lumbar schwannoma extirpation

Incidental or intentional durotomy causing cerebrospinal fluid (CSF) leakage, leading to the formation of a pseudomeningocele is a known complication in spinal surgery. Herniation of nerve roots into such a pseudomeningocele is very rare, but can occur up to years after initial durotomy and has been described to cause permanent neurologic deficit. However, cauda equina fiber herniation and entrapment into a pseudomeningocele has not been reported before. Here, we present a case of symptomatic transdural cauda equina herniation and incarceration into a pseudomeningocele, 3 months after extirpation of a lumbar Schwannoma. A 59-year-old man, who previously underwent intradural Schwannoma extirpation presented 3 months after surgery with back pain, sciatica and loss of bladder filling sensation caused by cauda equina fiber entrapment into a defect in the wall of a pseudomeningocele, diagnosed with magnetic resonance imaging. On re-operation, the pseudomeningocele was resected and the herniated and entrapped cauda fibers were released and replaced intradurally. The dura defect was closed and the patient recovered completely. In conclusion, CSF leakage can cause neurological deficit up to years after durotomy by transdural nerve root herniation and subsequent entrapment. Clinicians should be aware of the possibility of this potentially devastating complication. The present case also underlines the importance of meticulous dura closure in spinal surgery.

Operative treatment of anterior thoracic spinal cord herniation: three new cases and an individual patient data meta-analysis of 126 case reports

OBJECTIVE

Anterior thoracic spinal cord herniation is a rare cause of progressive myelopathy. Much has been speculated about the best operative treatment. However, no evidence in favor of any of the promoted techniques is available to date. Therefore, we decided to analyze treatment procedures and treatment outcomes of anterior thoracic spinal cord herniation to identify those factors that determine postoperative outcome.

METHODS

An individual patient data meta-analysis was conducted, focusing on age, gender, vertebral segment of herniation, preoperative neurological status, operative interval, operative findings, operative techniques, intraoperative neurophysiological monitoring, postoperative imaging, neurological outcome and follow-up. Three cases from our own institution were added to the material collected. Bivariate analysis tests and multivariate logistic regression tests were used so as to define which variables were associated with outcome after surgical treatment of anterior thoracic spinal cord herniation.

RESULTS

Brown-Séquard syndrome and release of the herniated spinal cord appeared to be strong independent factors, associated with favorable postoperative outcome. Widening of the dura defect is associated with the highest prevalence of postoperative motor function improvement when compared with the application of an anterior dura patch (P < 0.036).

CONCLUSION

Most patients with anterior thoracic spinal cord herniation require operative treatment because of progressive myelopathy. Patients with Brown-Séquard syndrome have a better prognosis with respect to postoperative motor function improvement. In this review, spinal cord release and subsequent widening of the dura defect were associated with the highest prevalence of motor function improvement. D-wave recording can be a very useful tool for the surgeon during operative treatment of this disorder.

Extradural thoracic spinal cord compression: unusual initial presentation of post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD) is a serious complication after solid-organ transplantation. We report a lung transplant recipient presenting with lower limb weakness as a result of extradural cord compression from PTLD. Diagnosis was made by laminectomy of T-3 with partial removal of the epidural mass. Further treatment consisted of chemoradiotherapy. The patient recovered completely. To our knowledge, this is the first reported case of PTLD presenting with signs and symptoms of spinal cord compression. The differential diagnosis of spinal cord compression in a patient who has had a transplant should include primary presentation of PTLD.

[Diagnosis and treatment of patients with spinal epidural metastases]

Three patients with a medical history of malignancy were referred for back pain: two women aged 53 and 43 years respectively, with breast cancer, and a woman of 85 years with rectal carcinoma. All patients suffered from spinal metastasis. Considerable delay occurred between the initial complaint of back pain and the diagnosis. This adversely influenced the outcome after treatment. A reliable differentiation, based on symptoms and signs, between widely occurring non-malignant back pain and back pain due to spinal metastasis is impossible. This confronts physicians with the dilemma of overexposing their patients to diagnostic tests on the one hand and the risk of missing an important diagnosis on the other. Early recognition of warning signs, i.e. previous medical history of malignancy, onset of back pain above 50 years of age, continuous pain not related to posture or movement and nocturnal pain, should alert physicians.

Neurenteric cyst--a case report of this rare disorder

Neurenteric cysts are rare congenital lesions that are believed to be the result of the split notochord syndrome. We report the clinical case of a 5-year-old boy presenting with vague gastrointestinal symptoms and fatigue, who had undergone resection of a small intestine duplication cyst as a newborn. Computed tomography revealed a mediastinal neurenteric cyst with partial destruction of several thoracic vertebrae. Resection of the tumor proved effective. Recognition of this disorder is important: because of its benign nature, the prognosis after surgical resection can be good. If the diagnosis is made in an early stage, unnecessary progressive destruction of surrounding structures may be prevented.

Image guided surgery: New technology for surgery of soft tissue and bone sarcomas

AIM

Providing the surgical oncologist with a new means of performing safe and radical sarcoma surgery with the help of image guidance technology.

METHOD

Two patients with pelvic sarcomas were operated upon with the help of an intra-operative navigation system. The technology of image guided surgery is described in one patient with a retroperitoneal sarcoma invading the bony pelvis and another patient with a chondrosarcoma of the iliac crest.

RESULTS

We show that this new procedure enables optimal radical surgical resection with minimal treatment related morbidity or loss of function.

CONCLUSION

Image guided surgery is a new technical tool in sarcoma surgery.

Anatomical and pathological considerations in percutaneous vertebroplasty and kyphoplasty: a reappraisal of the vertebral venous system

OBJECTIVES

To focus attention of the clinician on the anatomy and (patho)physiology of the vertebral venous system, so as to offer a tool to better understand and anticipate (potential) complications that are related to the application of percutaneous vertebroplasty and kyphoplasty.

BACKGROUND

Percutaneous vertebroplasty and kyphoplasty are newly developed, minimally invasive techniques for the relief of pain and for the strengthening of bone in vertebral body lesions. With the clinical implementation of these techniques, a number of serious neurologic and cardiopulmonary complications have been reported in the international medical literature. Most complications appear to be related to the extrusion of bone cement into the vertebral venous system.

METHODS

The literature about complications of percutaneous vertebroplasty and kyphoplasty is reviewed, and the anatomic and (patho)physiologic characteristics of the vertebral venous system are reported. Based on what is currently known from the anatomy and physiology of the vertebral venous system, the procedures of percutaneous vertebroplasty and kyphoplasty are analyzed, and suggestions are made to improve the safety of these techniques.

CONCLUSIONS

Thorough knowledge of the anatomic and (patho)physiologic characteristics of the vertebral venous system is mandatory for all physicians that participate in percutaneous vertebroplasty and kyphoplasty. To reduce the risk of cement extrusion into the vertebral venous system during injection, vertebral venous pressure should be increased during surgery. This can be achieved by operating the patient in the prone position and by raising intrathoracic venous pressure with the aid of the anesthesiologist during intravertebral instrumentation and cement injection. Intensive theoretical and practical training, critical patient selection, and careful monitoring of the procedures, also taking into account patient positioning and intrathoracic and intra-abdominal pressures, will help to facilitate low morbidity outcomes in these very promising minimally invasive techniques.

Innervation of "painful" lumbar discs

STUDY DESIGN

The authors investigated the innervation of discographically confirmed degenerated and "painful" human intervertebral discs.

OBJECTIVE

To determine the type and distribution patterns of nerve fibers present in degenerated human intervertebral discs.

SUMMARY OF BACKGROUND DATA

The innervation of intervertebral discs has previously been extensively described in fetal and adult animals as well as humans. However, little is yet known about the innervation of severely degenerated human lumbar discs. The question may be posed whether a disc that has been removed for low back pain possesses an increased innervation compared with normal discs.

METHODS

The presence of nerve fibers was investigated using acetylcholinesterase enzyme histochemistry, as well as neurofilament and substance P immunocytochemistry. From 10 degenerated and 2 control discs, the anterior segments were excised and their nerve distribution studied by examining sequential sections.

RESULTS

In all specimens, nerve fibers of different diameters were found in the anterior longitudinal ligament and in the outer region of the disc. In 8 of 10 degenerated discs, fibers were also found in the inner parts of the disc. Substance P-immunoreactive nerve fibers were sporadically observed in the anterior longitudinal ligament and the outer zone of the anulus fibrosus.

CONCLUSIONS

Findings indicate a more extensive disc innervation in the severely degenerated human lumbar disc compared with normal discs. The nociceptive properties of at least some of these nerves are highly suggested by their substance P immunoreactivity, which provides further evidence for the existence of a morphologic substrate of discogenic pain.