Anatomic considerations of the lumbar isthmus

Imaging anatomy study related to unilateral biportal endoscopic lumbar spine surgery

PURPOSE

To provide lumbar spine anatomical parameters relevant to the UBE technique and explore their intraoperative application.

METHODS

CT imaging data processed by Mimics for parametric measurements, including laminar abduction angle (LAA), laminar slope angle (LSA), minimum laminar height (MLH), distance between the inferior margin of the lamina and attachment of the ligamentum flavum onto the cephalad lamina (DLL), distance between the initial point and the middle of the articular process (DIA), and distance from the inferior margin of the lamina to the inferior border of the vertebral body (DLV), and were manually measured.

RESULTS

LAA and DIA gradually increase from L1 to L5. At L1, the DIA is approximately the length of 2 drill bits with a diameter of 3 mm (male: 7.77 ± 1.39 mm, female: 7.22 ± 1.09 mm), while at L5, it can reach the length of 4-5 drill bits (male: 14.96 ± 2.24 mm, female: 13.67 ± 2.33 mm). MLH, DLL, and DLV reach their maximum values at the L3 and decrease toward the cranial and caudal ends. The DLL is smallest at L5 (male: 9.58 ± 1.90 mm, female: 9.38 ± 2.14 mm), equivalent to the length of 3 drill bits, while the DLL at L3 is the length of 4-5 drill bits (male: 14.17 ± 2.13 mm, female: 14.01 ± 2.07 mm).

CONCLUSION

Referring to the drill diameter during surgery can mark the extent of laminotomy. The characteristics of vertebral plate angles at different lumbar levels can provide references for preoperative incision design.

Quantitative anatomical analysis of lumbar interspaces based on 3D CT imaging: optimized segment selection for lumbar puncture in different age groups

BACKGROUND

Optimal lumbar puncture segment selection remains controversial. This study aims to analyze anatomical differences among L3-4, L4-5, and L5-S1 segments across age groups and provide quantitative evidence for optimized selection.

METHODS

80 cases of CT images were collected with patients aged 10-80 years old. Threedimensional models containing L3-S1 vertebrae, dural sac, and nerve roots were reconstructed. Computer simulation determined the optimal puncture angles for the L3-4, L4-5, and L5-S1 segments. The effective dural sac area (ALDS), traversing nerve root area (ATNR), and area of the lumbar inter-laminar space (ALILS) were measured. Puncture efficacy ratio (ALDS/ALILS) and nerve injury risk ratio (ATNR/ALILS) were calculated. Cases were divided into four groups: A (10-20 years), B (21-40 years), C (41-60 years), and D (61-80 years). Statistical analysis was performed using SPSS.

RESULTS

1) ALDS was similar among segments; 2) ATNR was greatest at L5-S1; 3) ALILS was greatest at L5-S1; 4) Puncture efficacy ratio was highest at L3-4 and lowest at L5-S1; 5) Nerve injury risk was highest at L5-S1. In group D, L5-S1 ALDS was larger than L3-4 and L4-5. ALDS decreased after age 40. Age variations were minimal across parameters.

CONCLUSION

The comprehensive analysis demonstrated L3-4 as the optimal first-choice segment for ages 10-60 years, conferring maximal efficacy and safety. L5-S1 can serve as an alternative option for ages 61-80 years when upper interspaces narrow. This study provides quantitative imaging evidence supporting age-specific, optimized lumbar puncture segment selection.

Upper Lumbar Bone Stress Injuries in Elite Cricketers

OBJECTIVE

Describe the proportion of upper lumbar bone stress injuries (LBSI; T12-L3) relative to all LBSI, and the clinical presentation and diagnosis of upper LBSI in elite cricketers.

DESIGN

Case series.

SETTING

Professional domestic and international cricket teams over a 9-year period.

PARTICIPANTS

Elite Australian cricketers.

INDEPENDENT VARIABLES

Symptomatic upper LBSI diagnosed based on clinical findings and medical imaging.

MAIN OUTCOME MEASURES

Prevalence, injury history, and clinical management.

RESULTS

Twenty-four pace bowlers (22 male and 2 female) sustained 39 cases of upper LBSI (T12:2, L1:3, L2:20, L3:14). Upper lumbar vertebrae were involved in 41% (95% CI 31-51) of all LBSI in this cohort. Twenty-seven (69%, 54-81) cases had an injury that occurred only on the side contralateral to the bowling arm. Ipsilateral injuries tended to occur secondary to a contralateral nonunited defect. In all 7 cases with known radiology follow-up that had a contralateral then ipsilateral LBSI, the contralateral injury did not achieve bony union before the onset of the ipsilateral LBSI. For stress fractures with imaging follow-up, those who achieved bony union took longer to return to bowling training [median 152 days (IQR 117-188)], compared to those who achieved partial or no union [median 68 days (IQR 46-115)].

CONCLUSIONS

Upper LBSI in elite cricketers occurs in approximately 2 out of 5 cases of LBSI. Clinicians should allow sufficient time for upper LBSI to resolve and unite (if a fracture) because cases that returned to bowling training earlier were less likely to achieve bony union, and those that failed to unite commonly went on to have a recurrent LBSI.

LEVEL OF EVIDENCE

Therapy/prognosis/diagnosis level 2b.

Navigation assisted tubular resection of lumbar osteoid osteoma: how I do it

BACKGROUND

Osteoid osteoma is a benign primary bony tumor involving the spinal posterior arches. Surgical treatment is reserved to patients with severe pain or not responding to nonsteroidal anti-inflammatory medications. We report a minimally invasive transmuscular resection of an L5 isthmic osteoid osteoma, assisted by intraoperative 3D-fluoroscopy-based navigation.

METHODS

Navigation tracking reference is placed on the spinous process. A simil-scan with 3D-fluoroscopy is obtained to allow autoregistration for spinal navigation. Tubular transmuscular approach, directed to the ipsilateral isthmus and pedicle, is performed. Under navigation guidance, the lesion is identified and removed.

CONCLUSION

This technique is a safe and effective minimally invasive alternative to conventional surgical treatment of lumbar osteoid osteoma.

Percutaneous endoscopic-assisted direct repair of pars defect without general anesthesia could be a satisfying treatment alternative for young patient with symptomatic lumbar spondylolysis: a technique note with case series

Background

Multiple surgical procedures are applied in young patients with symptomatic lumbar spondylolysis when conservative treatments fail. Although the optimal surgical procedure option is controversial, the treatment paradigm has shifted from open surgery to minimally invasive spine surgery. To date, a limited number of studies on the feasibility of percutaneous endoscopic-assisted direct repair of pars defect have been carried out. Herein, for the first time, we retrospectively explore the outcomes of pars defect via percutaneous endoscopy.

Methods

We retrospectively examined young patients with spondylolysis treated using the percutaneous endoscopic-assisted direct repair of pars defect supplemented with autograft as well as percutaneous pedicle screw fixation between September 2014 and December 2018. Six patients with a mean age of 18.8 years were enrolled in the study. We used preoperatively computed tomographic (CT) scans to evaluate the size of pars defect, and graded disc degeneration using Pfirrmann’s classification through magnetic resonance images (MRI). We assessed the clinical outcomes using the Oswestry Disability Index (ODI), 36-Item Short-Form Health Survey (SF-36) as well as Visual Analogue Scale for back pain (VAS-B).

Results

Our findings revealed that pain intensity and function outcomes, including VAS-B, ODI, and SF-36 (PCS and MCS) scores, were markedly improved after surgery and at the final follow-up visit. The change in the gap distance of the pars defect was remarkably significant after surgery and during the follow-up period. Only one of the 12 pars repaired was reported as a non-union at the final follow-up visit. Moreover, no surgery-related complications were reported in any of the cases.

Conclusion

Percutaneous endoscopic-assisted direct repair of pars defect without general anesthesia, a minimally invasive treatment option, supplemented with autograft and percutaneous pedicle screw fixation, could be a satisfying treatment alternative for young patients with symptomatic lumbar spondylolysis.

Circumferential fusion for degenerative lumbar spondylolisthesis complicated by distal junctional grade 4 spondylolisthesis in the sub-acute post-operative setting

INTRODUCTION

Surgical management for lumbar stenosis is generally safe and provides significant improvements in pain, disability, and function. Successful lumbar decompression hinges on removing an appropriate amount of lamina and other compressive pathology in the lateral recess. Too little bony decompression can result in persistent pain and disability, while over resection of the pars and/or facets may jeopardize spinal stability.

CASE REPORT

In this unique report, we present for the first time an acute iatrogenic grade 4 L5-S1 spondylolisthesis distal to a L3-5 laminectomy and circumferential instrumented fusion due to bilateral iatrogenic L5 pars fractures and its management and clinical outcomes after revision operation. The patient presented with worsening pain, neurologic compromise, and severe sagittal imbalance. The iatrogenic, high-grade spondylolisthesis was urgently addressed with a L5-S1 anterior lumbar interbody fusion and extension of posterior instrumentation to the pelvis, which resulted in considerable pain relief, resolution of neurologic deficits, and reconstitution of acceptable sagittal imbalance.

CONCLUSION

All attempts during a lumbar decompression should be made to prevent iatrogenic pars fractures, as they may result in severe sagittal imbalance, neurologic compromise, and persistent disability. Iatrogenic, high-grade L5-S1 spondylolisthesis can be successfully treated with reduction using circumferential fusion of the lumbosacral junction.

Shape variation of the neural arch in the thoracic and lumbar spine: characterization and relationship with the vertebral body shape

Quantifying the human vertebral geometry is important for accurate medical procedures. We aimed to characterize the neural arch (NA) shape at T1-L5. All T1-L5 dry vertebrae (N = 4,080) of 240 individuals were measured and analyzed by age, gender, and ethnicity. A 3D digitizer was used to measure the dimensions of the spinous (SP) and transverse (TP) processes, vertebral canal (VC), laminae, and isthmus. Most parameters were independent of age and ethnicity, yet greater in males than in females. Isthmus length increases from T1 (9.8 mm) to T12 (19.87 mm) and decreases from T12 to L5 (9.68 mm) with right > left in the thorax and oppositely in the lumbar region. The SP is longer than its thickness both decreasing in the upper thorax (by ca. 4mm), increasing in the lower thoracic and upper lumbar vertebrae (by 7 mm for length and ca. 14.5 mm for thickness) and decreasing again along the lower lumbar vertebrae (both by 8 mm). The TP length decreases at T1-T12 (by 13 mm) and increases at L1-L5 with left > right at T1-L5 (P < 0.003). The laminar length decreases from T1 (8.72 mm) through T5 (4.76 mm) and increases toward L5 (8.4 mm) with right > left at T1-L5 (P < 0.003). The VC is oval-shaped at T1 and T11-L5 (width > length), rounded-shape at T2 and T10 (width = length), and inverted oval-shaped at T3-T9 (length > width). In conclusion, the NA is systematically asymmetrical and dynamic in shape along the thoracic and lumbar spine. The inter-relationship with the vertebral body and articular facets is discussed.

Spondylolysis and spondylolisthesis in children and adolescents

A review of the current literature shows that there is a lack of consensus regarding the treatment of spondylolysis and spondylolisthesis in children and adolescents. Most of the views and recommendations provided in various reports are weakly supported by evidence. There is a limited amount of information about the natural history of the condition, making it difficult to compare the effectiveness of various conservative and operative treatments. This systematic review summarises the current knowledge on spondylolysis and spondylolisthesis and attempts to present a rational approach to the evaluation and management of this condition in children and adolescents.

An anatomic and radiographic study of lumbar facets relevant to percutaneous transfacet fixation

STUDY DESIGN

An anatomic study of lumbar facet anatomy for transfacet fixation.

OBJECTIVE

Describe the ideal starting point and trajectory for percutaneous transfacet fixation.

SUMMARY OF BACKGROUND DATA

Percutaneous transfacet fixation is gaining popularity for posterior stabilization after anterior lumbar interbody fusion. Despite biomechanical and clinical studies, there are no anatomic guidelines for safe placement of percuatenous transfacet screws.

METHODS

Eighty L3-S1 facet joints from embalmed cadaveric spines were analyzed. Linear and angular measurements of the facets were recorded. Under direct visualization, the segments were pinned with an ipsilateral transfacet technique. The degrees of angulation in the sagittal and axial plane were recorded. The distances of the starting point relative to landmarks of the superior body were measured. Under fluoroscopy, radiographic parameters for ideal visualization of the pin and pin ending points were determined.

RESULTS

Inferior and superior facet heights ranged from 15.7 to 17.5 mm at all levels. The percentage of inferior facet extending below the L3 and L4 end plates was 84% and 86% respectively and decreased at L5 to 72%. The percentage of superior facet extending above the end plate ranged from 36% to 44% at all levels. The transverse facet angle progressively increased from L3 to S1. The L2-L3 segments could not be instrumented from the ipsilateral side due to the vertical facet orientation. For L3-S1 segments, the starting point in the coronal plane is based on the superior body of the instrumented segment and should be in line with the medial border of the pedicle in the medial-lateral direction and in line with the inferior end plate in the cranial-caudal direction. The screw should be laterally angulated approximately 15 degrees in the axial plane approximately 30 degrees caudally in the sagittal plane. The screw should end in the inferolateral quadrant of the pedicle on the AP radiograph and at the pedicle-vertebral body junction on the lateral radiograph. 35 degrees of axial rotation is the optimal fluoroscopic view for confirming screw placement.

CONCLUSION

Ipsilateral transfacet fixation can be successfully performed in the L3-S1 segments by using the inferior end plate and medial pedicle wall of the superiorly instrumented level as anatomic landmarks in conjunction with axial and sagittal angles of insertion.

The effect of removing the lateral part of the pars interarticularis on stress distribution at the neural arch in lumbar foraminal microdecompression at L3-L4 and L4-L5: anatomic and finite element investigations

STUDY DESIGN

The assessment of L3 and L4 pars interarticularis thickness and finite element analysis of stress distribution across L3 and L4 pars interarticularis.

OBJECTIVE

To quantify the morphology of the region of the L3 and L4 pars interarticularis and to assess the stress increase as a function of access size using the finite element lumbar spine model.

SUMMARY OF BACKGROUND DATA

Inadequate decompression and traction of the nerve structures are several causes of the unsatisfactory outcomes in patients after foraminal stenosis decompression and far lateral disc herniation removal by extraforaminal exposure. Enlarging the access of the foraminal exposure by the removal of the lateral aspect of the pars interarticularis may be able to diminish the inadequate decompression and traction of the nerve structures; however, it may lead to increase stress and fracture of the neural arch.

METHODS

We used 15 human cadaver L3 and L4 lumbar vertebrae for measuring the thickness of the pars interarticularis. The ventral and dorsal surfaces were subdivided into 4 equal parts, and the thickness of each part was measured using a digital caliper. An experimentally validated 3-dimensional nonlinear finite element model of the intact L3-S1 segment was used to simulate the lateral removal of one fourth and one half of the L3 and L4 pars interarticularis.

RESULTS

The mean thicknesses of the pars interarticularis showed a gradual increase toward the lateral edge. Finite element model analyses predicted stresses increased to 35% and 40% after removal of one half of the lateral part of the L3 and L4 pars interarticularis, respectively, and were much closer to the intact spine after removal of one fourth of the lateral part of the pars interarticularis.

CONCLUSION

The removal of one fourth of the lateral aspect of the pars interarticularis has minimal influence on the stresses in the remaining L3 and L4 neural arches. The lateral half of the pars has the largest thickness, and its removal leads to considerable stress increases.

Direct repair of defects in lumbar spondylolysis with a new pedicle screw hook fixation: clinical, functional and Ct-assessed study

Spondylolysis is a common entity, a minority of people affected by this disease need medical care, and only a few require surgery. Reconstruction of the pars interarticularis is an interesting alternative to segmental fusion; this technique has the advantage of preserving segmental motion. Most authors report good results for young patients without intervertebral disk or facet degenerative changes. Moreover Louis also showed good to excellent results with his technique carried out among people who presented a satisfactory disk height (equal to two thirds of normal height). This could extend the number of patients for whom pars interarticularis repair could be proposed. In this study, the limit of reconstruction was set at grade 3 of the Pfirrmann's classification. The fixation of the isthmus was done with a new kind of pedicle screw hook system. This stable and strong device is easy to use, allows an anatomic pars interarticularis reconstruction of spondylolysis and avoids a postoperative bracing. Twenty-three patients were assessed in this study, the mean age at operation was 34 (range 16-52 years) and the average follow-up was for 59 months (range 6-113 months). Eight patients showed moderate degenerative disk disease before the surgery and 12 patients had a grade 1 spondylolisthesis. The visual analogical scale, the Oswestry disability index (ODI) and the modified Prolo score were used for assessment of pain and clinical outcome before and after surgery. The results were from "excellent" to "good" for twenty patients (87%) and "fair" for three of them (13%). The consolidation of the isthmus was assessed at the end of the study (CT-scan); the fusion rate was observed in 91%. Among patients aged less than 30 years results are from "good", to "excellent" in all cases and consolidation was always observed. All of them showed normal disc signal before the surgery. In the group aged more than 30 years, the results varied from "good" to "excellent' in 73% and fusion of the defect was discovered in 82% of cases. Eight of them (73%) had moderate disk signal modification before the surgery. All people with fair results displayed moderate disk degeneration signs at MRI before surgery; but two of those three patients had a failure of defect consolidation too and it is also associated with poor results by several authors. No complication was found in this series. According to the good results reported by Louis and upto the current finding, the authors believe that pars interarticularis repair can be carried out on patients with moderate degenerative disk disease; the stage 3 of Pfirrmann's classification seems a good limit. The Bone and joint research (B.J.R. system) is readily usable by any surgeon using pedicle screw systems and having a short learning curve. No device failure has been observed in this series.

Basic Science Research Related to Chiropractic Spinal Adjusting: The State of the Art and Recommendations Revisited

OBJECTIVE

The objectives of this white paper are to review and summarize the basic science literature relevant to spinal fixation (subluxation) and spinal adjusting procedures and to make specific recommendations for future research.

METHODS

PubMed, CINAHL, ICL, OSTMED, and MANTIS databases were searched by a multidisciplinary team for reports of basic science research (since 1995) related to spinal fixation (subluxation) and spinal adjusting (spinal manipulation). In addition, hand searches of the reference sections of studies judged to be important by the authors were also obtained. Each author used key words they determined to be most important to their field in designing their individual search strategy. Both animal and human studies were included in the literature searches, summaries, and recommendations for future research produced in this project.

DISCUSSION

The following topic areas were identified: anatomy, biomechanics, somatic nervous system, animal models, immune system, and human studies related to the autonomic nervous system. A relevant summary of each topic area and specific recommendations for future research in each area were the primary objectives of this project.

CONCLUSIONS

The summaries of the literature for the 6 topic sections (anatomy, biomechanics, somatic nervous system, animal models, immune system, and human studies related to the autonomic nervous system) indicated that a significant body of basic science research evaluating chiropractic spinal adjusting has been completed and published since the 1997 basic science white paper. Much more basic science research in these fields needs to be accomplished, and the recommendations at the end of each topic section should help researchers, funding agencies, and other decision makers develop specific research priorities.

Direct Repair of Spondylolysis Using a New Pedicle Screw Hook Fixation: Clinical and CT-Assessed Study

OBJECTIVE

A prospective analysis of 19 consecutive cases of spondylolysis repair using a new hook screw device is presented. The objective of the study was to assess the clinical, radiologic, and computed tomography (CT) scan outcomes to establish the indications of isthmic repair in the treatment of spondylolysis.

METHODS

Nineteen patients treated with a new segmental pedicle screw hook fixation were followed up for a minimum of 2 years (mean 30 months, range 24-48 months). Mean age was 20.5 years (range 13-29 years). All lytic defects were bilateral and located at L5, except for one at L3. CT scans were obtained at 6 months and 1 year postoperatively. CT scans were performed using both traditional and reverse gantry angled cuts to assess the healing of the defect. Fusion was considered to be present when trabeculae passed across the lytic defect. CT scan images were not considered conclusive until 1 year after surgery, because in two cases, trabecular pass across the pars was observed on only one side after 6 months, becoming bilateral 1 year postoperatively.

CONCLUSIONS

Twelve of 13 patients who were 20 years or younger at the time of the study (average age 17.2 years) had fusion (92%), whereas in the group of 6 patients age 21 and older (average age 27.5 years), no cases of fusion were observed. Clinical outcome was excellent to good in 15 patients, fair in 3 cases, and poor in 1. The group of patients age 20 or younger had significantly better clinical results (84% excellent or good) (P = 0.00097) than those obtained in the group of patients age 21 and older (66% excellent or good) (P = 0.016). According to the current findings, the authors believe that segmental pedicle screw hook fixation is a useful alternative in the treatment of spondylolysis in adolescents but do not recommend this procedure in patients over age 20.

Symptomatic spondylolysis: diagnosis and treatment

PURPOSE OF REVIEW

Approximately 35% of adolescents experience back pain. In athletic adolescents, spondylolysis is the most common offending cause. With growing numbers of adolescents participating in sports with higher levels of intensity, spondylolysis is becoming an increasingly common clinical problem.

RECENT FINDINGS

A recent report demonstrated the benign natural history of asymptomatic spondylolysis. However, long-term follow-up studies of patients who experience painful spondylolysis as adolescents remain unavailable. Modern imaging modalities have led to earlier diagnosis with greater accuracy. Conservative management with bracing continues to be a mainstay of treatment. In patients who are not helped by conservative therapy, recent studies have demonstrated the satisfactory long-term results of surgical repair.

SUMMARY

The long-term sequelae of symptomatic spondylolysis and unhealed pars defects require investigation. MRI promises to be a valuable tool for diagnosis and clinical stratification, but further studies are necessary to demonstrate its clinical utility.

The lateral buttress: an anatomic feature of the lumbar pars interarticularis

STUDY DESIGN

A morphometric study of the lateral buttress region of the lumbar pars interarticularis from L1-L5 on 10 dried lumbar spines was performed.

OBJECTIVE

To qualitatively describe and quantitatively evaluate this portion of the pars and to discuss its clinical and surgical relevance.

BACKGROUND

The "lateral buttress" is a bony bridge connecting the superolateral edge of the inferior facet to the pedicle/transverse process junction, offering structural support to the pars interarticularis at upper lumbar levels. To date, no anatomic study has evaluated this structure.

METHODS

Direct measurements using vernier calipers were taken at each level, L1-L5, from 10 dried lumbar spines. Surface area of the buttress was calculated and compared statistically for differences between each level, as well as normalized relative to L3.

RESULTS

The surface areas of the buttresses at L1-L3 were similar, measuring near 80 +/- 10 mm2. At L4, it measured 50 +/- 10 mm2. And at L5, it measured 15 +/- 5 mm2. These differences were statistically significant. Normalized data showed the buttress at L4 to be 40% smaller and at L5 to be 80% smaller than at upper levels.

CONCLUSIONS

This study provides descriptive and anatomic data regarding the lateral buttress portion of lumbar pars interarticularis. The broad buttress of the upper lumbar levels offers support to the pars but can confuse anatomic guidelines for pedicle screw placement and paraspinal approaches. The narrow buttress of lower lumbar levels makes pedicle screw placement and the paraspinal approach easier, but it lessens support to the pars, making spondylolysis and iatrogenic instability more likely.

Analysis of vertebral morphology in idiopathic scoliosis with use of magnetic resonance imaging and multiplanar reconstruction

BACKGROUND

Several studies have provided data on the vertebral morphology of normal spines, but there is a paucity of data on the vertebral morphology in patients with idiopathic scoliosis.

METHODS

The morphology of the pedicles and bodies of 307 vertebrae as well as the distance between the pedicles and the dural sac (the epidural space) in twenty-six patients with right-sided thoracic idiopathic scoliosis were analyzed with use of magnetic resonance imaging and multiplanar reconstruction.

RESULTS

A distinct vertebral asymmetry was found at the apical region of the thoracic curves, with significantly thinner pedicles on the concave side than on the convex side (p < 0.05). The degree of intravertebral deformity diminished farther away from the apex, with vertebral symmetry restored at the neutral level. In the thoracic spine, the transverse endosteal width of the apical pedicles measured between 2.3 mm and 3.2 mm on the concave side and between 3.9 mm and 4.4 mm on the convex side (p < 0.05). In the lumbar spine, the pedicle width measured between 4.6 mm at the cephalad part of the curve and 7.9 mm at the caudad part of the curve. The chord length and the pedicle length gradually increased from 34 mm and 18 mm, respectively, at the fourth thoracic vertebra to 51 mm and 25 mm, respectively, at the third lumbar vertebra. The transverse pedicle angle measured 15 in the cephalad aspect of the thoracic spine, decreased to 7 at the twelfth thoracic vertebra, and increased again to 16 at the fourth lumbar vertebra. The width of the epidural space was <1 mm at the thoracic apical vertebral levels and averaged 1 mm at the lumbar apical vertebral levels on the concave side, whereas it was between 3 mm and 5 mm on the convex side (p < 0.05).

CONCLUSION

Idiopathic scoliosis is associated with distinctive intravertebral deformity, with smaller pedicles on the concave side and a shift of the dural sac toward the concavity.

Osseous anatomy of the lumbosacral spine in Marfan syndrome

STUDY DESIGN

This study examines pedicle widths, laminar thicknesses, and scalloping values for lumbosacral spine elements in Marfan volunteers. Comparisons were made between these measurements and norms as well as measurements between Marfan patients with and without dural ectasia.

OBJECTIVES

To determine if the lumbosacral vertebral elements are altered in the patient with Marfan syndrome.

SUMMARY OF BACKGROUND DATA

Several abnormalities have been noted in Marfan lumbar spine, including pedicular attenuation and widened interpediculate distances. This may be due to abnormalities of growth or presence of dural ectasia. Given the large numbers of Marfan patients requiring spinal surgery and the high postoperative failure rate, better understanding of the bony anatomy of Marfan lumbar spine is necessary, especially if use of instrumentation is anticipated.

METHODS

Thirty-two volunteers with Marfan syndrome based on the Ghent criteria underwent spiral computed tomography of the lumbosacral spine. Images were evaluated for dural ectasia, and measurements of pedicle width, laminar thickness, and vertebral scalloping were made.

RESULTS

Pedicle widths and laminar thicknesses were significantly smaller in Marfan patients at all levels (P<0.001). Mean pedicle widths at L1-L3 were smaller than the smallest available pedicle screw (5 mm). In Marfan patients with dural ectasia, laminar thickness from L5-S2 and pedicle widths at all lumbar levels were significantly reduced (P<0.01). Vertebral scalloping at S1 was significantly greater in Marfan patients with dural ectasia (P = 0.02).

CONCLUSION

Lumbar pedicle width and laminar thickness are significantly reduced in Marfan individuals. Those with dural ectasia demonstrate increased bony erosion of anterior and posterior elements of lumbosacral spine. Preoperative planning and routine computed tomography scans are recommended when operating on Marfan lumbosacral spine.