CASE REPORTJ Neurosurg Spine 26:430–434, 2017

Congenital hypoplasia of the spinal pedicle is an uncommon anomaly. When it occurs, it mostly in-volves the cervical or thoracic spine; the absence of

a lumbar or sacral pedicle is rare.3,5,6,9,20,21,26 The majority of cases with an absence or hypoplasia of the lumbosacral pedicles are asymptomatic, and they are usually discov-ered incidentally. Low-back pain is the most frequently re-ported symptom.6 The rarer cases present with intractable low-back pain or neurological impairment requiring sur-gery. Most patients are treated with posterior instrument-ed fusion; however, hypoplasia of the lumbar pedicle may increase the difficulties associated with the pedicle screw fixation and fusion. Herein, we present 2 cases of unilat-eral hypoplasia of the pedicles in the lumbar spine with concurrent spondylolisthesis, leading to low-back pain and radicular pain of the lower extremities. The surgical strat-egy in these cases consisted of anterior lumbar interbody fusion (ALIF), followed by percutaneous pedicle screw fixation (PPF) without posterior decompression.

Case ReportsCase 1History and Examination

A 63-year-old man presented with chronic low-back pain and severe radicular pain in the right lower extrem-ity. Prior conservative treatment with physical therapy and medication was unsuccessful. Physical examination revealed decreased muscle power in bilateral big toe dor-siflexion (Grade 4/5 on the Medical Research Council [MRC] motor scale).19 All modalities of sensation were intact. To assess low-back and radicular pain, we used a visual analog scale (VAS) for pain (0 indicated no pain; 10 indicated the worst pain). Preoperative VAS scores for low-back and leg pain were 6 and 8, respectively. The deep tendon reflexes were 2+ bilaterally. The standing weight-bearing radiographs of the lumbar spine revealed hypopla-sia of the right L-4 pedicle and Meyerding Grade I spon-dylolisthesis at the L4–5 level (Fig. 1).13 A CT scan of the

ABBREVIATIONS ALIF = anterior lumbar interbody fusion; MRC = Medical Research Council; PPF = percutaneous pedicle screw fixation; VAS = visual analog scale.SUBMITTED January 10, 2016. ACCEPTED August 3, 2016.INCLUDE WHEN CITING Published online January 6, 2017; DOI: 10.3171/2016.8.SPINE151137.

Congenital hypoplasia of the lumbar pedicle with spondylolisthesis: report of 2 casesChang-Sheng Hsieh, MD,1 Sang-Ho Lee, MD, PhD,2 Hyung Chang Lee, MD,3 Hyeong-Seok Oh, MD,4 Byeong-Wook Hwang, MD, PhD,4 Sang-Joon Park, MD,4 and Jian-Han Chen, MD5,6

Departments of 1Orthopaedics and 4Neurosurgery, Wooridul Spine Hospital, Busan; 2Department of Neurosurgery, Wooridul Spine Hospital, Seoul; 3Department of Cardiovascular Surgery, Wooridul Spine Hospital, Gimpo Airport, Seoul, Korea; 5Department of General Surgery, Buddhist Dalin Tzu Chi Hospital, Chia-Yi; and 6School of Medicine, Tzu Chi University, Hualien, Taiwan

Congenital hypoplasia of the spinal pedicle is a rare condition. Previously reported cases were treated conservatively or with posterior instrumented fusion. However, the absence or hypoplasia of the lumbar pedicle may increase the difficulty of pedicle screw fixation and fusion. Herein, the authors describe 2 cases of rare adult congenital hypoplasia of the right lumbar pedicles associated with spondylolisthesis. The patients underwent anterior lumbar interbody fusion with a stand-alone cage as well as percutaneous pedicle screw fixation. This method was used to avoid the difficulties associ-ated with pedicle screw fixation and to attain solid fusion. Both patients achieved satisfactory outcomes after a minimum of 2 years of follow-up. This method may be an alternative for patients with congenital hypoplasia of the lumbar spinal pedicle.https://thejns.org/doi/abs/10.3171/2016.8.SPINE151137KEY WORDS congenital hypoplasia; lumbar pedicle; spondylolisthesis

©AANS, 2017J Neurosurg Spine Volume 26 • April 2017430

Unauthenticated | Downloaded 08/14/20 08:21 AM UTC

Congenital hypoplasia of lumbar pedicle with spondylolisthesis

J Neurosurg Spine Volume 26 • April 2017 431

lumbar spine revealed hypoplasia of the right L-4 pedicles and articulating processes (Fig. 2 left). On the left side, there was degeneration of the L4–5 facet joints, with frac-ture of the pars interarticularis (Fig. 2 right).

TreatmentWe performed an ALIF with the SynFix system (Syn-

thes Spine Inc.) and screws. The percutaneous pedicle screws were fixed via the paramedian approach on the left side of L4–5. Posterior decompression was not performed during surgery.

Postoperative CourseThe patient’s postoperative VAS scores for low-back

and radicular pain reduced to 1 and 0, respectively. Physi-cal examination revealed normalization of muscle power

in bilateral big toe dorsiflexion (MRC Grade 5/5). The dy-namic radiograph of the lumbosacral spine revealed bony fusion with no evidence of pseudarthrosis at the 2-year follow-up (Fig. 3).

Case 2History and Examination

An 84-year-old man presented with chronic low-back pain and radicular pain that radiated to the bilateral lower extremities. Preoperative VAS scores for the low-back and radicular pain were both 8. Physical examination re-vealed decreased muscle power in both right and left big toe dorsiflexion (MRC Grades 2/5 and 4/5, respectively). There was also a reduction in the power of bilateral ankle dorsiflexion (MRC Grade 4/5 bilaterally). All modalities of sensation were intact. The deep tendon reflexes were 2+ bilaterally. The standing weight-bearing radiographs of the lumbar spine revealed hypoplasia of the right L-5 pedicle and Meyerding Grade I spondylolisthesis at the L4–S1 level (Fig. 4). A CT scan of the lumbar spine dem-onstrated hypoplasia of the right L-5 pedicle, fracture of the L-5 pedicle root, and L4–5 foraminal stenosis (Fig. 5).

TreatmentThe patient’s low-back and radicular pain did not im-

prove with conservative treatment; therefore, we per-formed an ALIF using the SynFix system with screws at the L4–5 and L5–S1 levels. Additionally, we used PPF via the paramedian approach bilaterally at the L-4 and S-1 levels. Posterior decompression was not performed during surgery. The pedicle screws were augmented with poly-methylmethacrylate (PMMA) cement due to severe osteo-porosis (bone mineral density of the femoral neck -3.3).

Postoperative CourseThe patient’s postoperative VAS scores for low-back

and radicular pain reduced to 1 and 0, respectively. Physi-

FIG. 1. Case 1. Left: Anteroposterior radiograph of the lumbosacral spine reveals hypoplasia of the right L-4 lumbar pedicle (arrow-head). Right: Lateral view. A neutral weight-bearing radiograph shows Meyerding Grade I spondylolisthesis at the L4–5 level.

FIG. 3. Case 1. Six-month postoperative radiographs. Left: Anteropos-terior view. Right: Lateral view. The patient was treated with ALIF using a SynFix cage and left-sided pedicle screw fixation.

FIG. 2. Case 1. Axial and sagittal CT (without contrast) scans of the lumbosacral junction. Left: An axial reconstruction of spinal CT scans demonstrates congenitally hypoplastic right L-4 pedicles and articulating processes (arrowhead). Right: The severely degenerated hyperplastic contralateral L4–5 facet joints including the fracture of the pars interar-ticularis (arrowhead).

Unauthenticated | Downloaded 08/14/20 08:21 AM UTC

C. S. Hsieh et al.

J Neurosurg Spine Volume 26 • April 2017432

cal examination revealed improved muscle power in bi-lateral big toe dorsiflexion: MRC Grades 4/5 and 5/5 on the right and left sides, respectively. Additionally, bilateral ankle dorsiflexion normalized to MRC Grade 5/5. The dynamic radiograph of the lumbosacral spine revealed solid bony fusion with no evidence of pseudarthrosis at the 2-year follow-up (Fig. 6).

DiscussionDysgenesis or agenesis of the spinal pedicle is thought

to result from a large retrosomatic cleft during embryo-logical development.20 These clefts can occur in a variety of locations within the vertebral arch. They can also occur in the pedicles and have been reported from levels T-12 to S-1.4,5 Their cause is uncertain.24 Congenital hypoplasia of a pedicle at the lumbosacral junction can result in ac-companying dysfunction or deformity of the facet joint, which is more critical to biomechanical stability than the hypoplasia of the pedicle itself.6

The main role of facet joints in the lumbosacral spine is to stabilize extension and rotation stress.11,22 Biomechani-cal tests have revealed that total unilateral facetectomy significantly increases the instability of the lumbosacral spine axial rotation and flexion.1 Another function of the facet joint is to distribute the axial load at each level. The load carried by facet joints varies from 9% (neutral) to 15% (extension). If one of these joints is incompetent, the contralateral joint must bear a greater load.8 Case 1 in this study showed a similar type of overload and instability in the lumbar spine, resulting in severe degenerative changes in the contralateral L4–5 facet joints. Kaito et al.6 report-ed a similar case that was missing the right L-5 pedicle, which led to severe degenerative changes in the contralat-eral facet joint.

Radiological evaluation of these patients typically begins with conventional radiography and frequently in-cludes CT, myelography, and MRI.17,23 According to Wie-ner et al.,25 this congenital anomaly has the following ra-

diographic features: 1) the false appearance of an enlarged ipsilateral neural foramen because of the absent pedicle; 2) a dysplastic, dorsally displaced ipsilateral articular pillar and lamina; and 3) a dysplastic ipsilateral transverse pro-cess. The spectrum of this anomaly also includes the ab-sence of the ipsilateral pillar or the entire ipsilateral neural arch, as well as other osseous anomalies in more than half of the cases.

The main data collected from the literature are shown in Table 1. Previously reported cases of pedicle hypoplasia or absence were mostly asymptomatic; if present, the only symptom was low-back pain that was well controlled by conservative treatment.12,14,15,21,27 The rarer cases present-ing with intractable low-back pain or neurological impair-ment required surgery.6,17,18 Most of the patients were treat-ed with posterior instrumented fusion. However, lumbar pedicle hypoplasia can increase the difficulties associated with pedicle screw fixation and fusion.

The optimal surgical method for spondylolisthesis re-

FIG. 4. Case 2. Left: Anteroposterior radiograph of the lumbosacral spine reveals spondylosis and mild scoliosis. Right: A neutral weight-bearing radiograph shows spondylosis and Meyerding Grade I spondy-lolisthesis at the L4–S1 level.

FIG. 6. Case 2. Six-month postoperative radiographs. Left: Antero-posterior view. Right: Lateral view. The patient underwent ALIF with SynFix cages and screws over L4–5 and L5–S1, and bilateral L-4 and S-1 pedicle screw fixation.

FIG. 5. Case 2. Sagittal and axial CT scans (without contrast) of the lumbosacral junction. Left: This sagittal reconstruction of spinal CT scans demonstrates hypoplasia of the right L-5 pedicle (arrowhead) and L4–5 foraminal stenosis. Right: An axial reconstruction of spinal CT scans demonstrates hypoplasia of the right L-5 pedicle (arrow) and pedicle defect.

Unauthenticated | Downloaded 08/14/20 08:21 AM UTC

Congenital hypoplasia of lumbar pedicle with spondylolisthesis

J Neurosurg Spine Volume 26 • April 2017 433

mains controversial. Several authors have demonstrated the effectiveness of ALIF in terms of the following ad-vantages: preservation of posterior midline complexes, low risk of neural complication, less blood loss, and high fusion rate. Although a stand-alone ALIF cage is an effec-tive construct for low-grade spondylolisthesis, nonunion and pseudarthrosis are possible complications. Recent studies have shown that ALIF with PPF can be performed to attain the surgical goals and successful outcomes in the management of isthmic spondylolisthesis.2,7 However, hypoplasia of the lumbar pedicle also increases the dif-ficulty of performing PPF. In the cases featured in this pa-per, we performed PPF only for normal pedicles. We used a stand-alone cage augmented with screws to increase stability given concerns of pseudarthrosis. Both patients underwent the combined procedures without posterior de-compression, and solid fusions were achieved.

Although Patel et al. also performed posterior instru-mented fusion without decompression,17 2-level fusion was applied in their patients. In our study, both patients underwent only single-level fusion; this allowed for the preservation of adjacent normal spinal segments. Our patients reported satisfactory functional outcomes at the 2-year follow-up. Anterior lumbar interbody fusion with a stand-alone cage followed by PPF avoids the difficulties associated with pedicle screw fixation and provides suffi-cient fusion stability. Percutaneous pedicle screw fixation has the advantages of a shorter surgical time, less paraspi-nal muscle damage, and lower blood loss, compared with open pedicle screw fixation. The procedures performed in our cases resulted in favorable clinical outcomes and

fusion. Further studies are necessary to corroborate our results.

ConclusionsCongenital hypoplasia of the lumbar spine pedicle is

rare. Therefore, it is important to recognize this anom-aly as an unusual cause of low-back and radicular pain. Lumbar pedicle hypoplasia can increase the difficulty of pedicle screw fixation and fusion. Anterior lumbar inter-body fusion with a stand-alone cage followed by PPF can provide solid fusions and avoid the difficulties associat-ed with pedicle screw fixation, as demonstrated in our 2 adult patients, in whom successful fusion and satisfactory functional outcomes were reported at the 2-year follow-up. This method may be an alternative for patients with congenital hypoplasia of the lumbar spinal pedicle with spondylolisthesis.

AcknowledgmentsThis study was supported by a grant from the Wooridul Spine

Hospital.

References 1. Abumi K, Panjabi MM, Kramer KM, Duranceau J, Oxland

T, Crisco JJ: Biomechanical evaluation of lumbar spinal stability after graded facetectomies. Spine (Phila Pa 1976) 15:1142–1147, 1990

2. Choi KC, Kim JS, Shim HK, Ahn Y, Lee SH: Changes in the adjacent segment 10 years after anterior lumbar interbody

TABLE 1. Literature summary of cases of hypoplasia or absence of lumbar pedicle

Authors & YearLevel & No.

of Cases

Age (yrs)/Sex

Signs & Symptoms Radiological Findings Management Outcome FU

Patel et al., 2013 Bilat L-5, 1 13/F LBP, radiculopathy Bilat hypoplasia of L-5 VB & pedicle; spondylolisthesis Grade I

PI over L-4 & S-1, w/o decompression

Resolution of pain & good bony fusion

18 mos

Lt S-1, 1 10/F LBP, radiculopathy Absent lt S-1 pedicle, Grade I anterolisthesis

PI over bilat L-5, rt S-1 & lt S-1 alar screw w/o decompression

Resolution of pain & good bony fusion

5 mos

Kaito et al., 2005 Rt L-5, 1 54/M LBP, radiculopathy Absence of rt L-5 pedicle Conservative treatment NR NRSener et al., 1991 Rt L-5, 1 34/M LBP Absence of rt L-5 pedicle Conservative treatment NR NR Polly & Mason,

1991Rt L-6, 1 12/F LBP, radiculopathy Absence of rt L-6 pedicle, con-

joined nerve root at L6–S1NR NR NR

Rt L-4, 1 14/M LBP Absence of rt L-4, T-L scoliosis Conservative treatment Resolution of pain 6 mosLt L-5, 1 19/F LBP Absence of rt L-5 pedicle L4–S1 PLF Resolution of pain NR Rt L-5, 1 17/M LBP Absence of rt L-5 pedicle,

spondylolysisPLF Resolution of pain NR

Mizutani et al., 1989

Lt L-1, 1 10/M LBP Absence of lt L-1 pedicle & VB, hypoplasia of lt T-12, L-2, L-3, & L-5 pedicles

Conservative treatment Resolution of pain 2 yrs

Lederman & Kaufman, 1986

T11–12, 1 12/M Nonspecific ab pain, no LBP

Hypoplasia of lt T-11 pedicle, absence of rt T-12 pedicle

No further workup or therapy

No back pain NR

ab = abdominal; FU = follow-up; LBP = low-back pain; NR = not reported; PI = posterior instrumentation; PLF = posterior lateral fusion; T-L = thoracolumbar; VB = vertebral body.

Unauthenticated | Downloaded 08/14/20 08:21 AM UTC

C. S. Hsieh et al.

J Neurosurg Spine Volume 26 • April 2017434

fusion for low-grade isthmic spondylolisthesis. Clin Orthop Relat Res 472:1845–1854, 2014

3. De Boeck M, De Smedt E, Potvliege R: Computed tomogra-phy in the evaluation of a congenital absent lumbar pedicle. Skeletal Radiol 8:197–199, 1982

4. Dietemann JL, Macedo R, Medjek L, Babin E, Wackenheim A: [Bilateral pedicular cleft in a patient with neurofibromato-sis (author’s transl).] Ann Radiol (Paris) 24:665–667, 1981 (Fr)

5. Johansen JG, McCarty DJ, Haughton VM: Retrosomatic clefts: computed tomographic appearance. Radiology 148:447–448, 1983

6. Kaito T, Kato Y, Sakaura H, Yamamoto K, Hosono N: Congenital absence of a lumbar pedicle presenting with contralateral lumbar radiculopathy. J Spinal Disord Tech 18:203–205, 2005

7. Kim KH, Lee SH, Lee DY, Shim CS, Maeng DH: Anterior bone cement augmentation in anterior lumbar interbody fu-sion and percutaneous pedicle screw fixation in patients with osteoporosis. J Neurosurg Spine 12:525–532, 2010

8. Kornberg M: Spondylolisthesis with unilateral pars interar-ticularis defect and contralateral facet joint degeneration. A case report. Spine (Phila Pa 1976) 13:712–713, 1988

9. Lauten GJ, Wehunt WD: Computed tomography in absent cervical pedicle. AJNR Am J Neuroradiol 1:201–203, 1980

10. Lederman HM, Kaufman RA: Congenital absence and hy-poplasia of pedicles in the thoracic spine. Skeletal Radiol 15:219–223, 1986

11. Lorenz M, Patwardhan A, Vanderby R Jr: Load-bearing characteristics of lumbar facets in normal and surgically altered spinal segments. Spine (Phila Pa 1976) 8:122–130, 1983

12. Macleod S, Hendry GM: Congenital absence of a lumbar pedicle. A case report and a review of the literature. Pediatr Radiol 12:207–210, 1982

13. Meyerding HW: Spondylolisthesis. Surg Gynecol Obstet 54:371–379, 1932

14. Mizutani M, Yamamuro T, Shikata J: Congenital absence of a lumbar pedicle. Spine (Phila Pa 1976) 14:890–891, 1989

15. Morin ME, Palacios E: The aplastic hypoplastic lumbar ped-icle. Am J Roentgenol Radium Ther Nucl Med 122:639–642, 1974

16. Oh YM, Eun JP: Congenital absence of a cervical spine pedicle: report of two cases and review of the literature. J Korean Neurosurg Soc 44:389–391, 2008

17. Patel AJ, Vadivelu S, Desai SK, Jea A: Congenital hypoplasia

or aplasia of the lumbosacral pedicle as an unusual cause of spondylolisthesis in the pediatric age group. J Neurosurg Pediatr 11:717–721, 2013

18. Polly DW Jr, Mason DE: Congenital absence of a lumbar pedicle presenting as back pain in children. J Pediatr Or-thop 11:214–219, 1991

19. Seddon HJ (ed): Peripheral Nerve Injuries. London: HM Stationery Office, 1954

20. Sener RN: Sacral pedicle agenesis. Comput Med Imaging Graph 21:361–363, 1997

21. Sener RN, Ripeckyj GT, Jinkins JR: Agenesis of a lumbar pedicle: MR demonstration. Neuroradiology 33:464, 1991

22. Sharma M, Langrana NA, Rodriguez J: Role of ligaments and facets in lumbar spinal stability. Spine (Phila Pa 1976) 20:887–900, 1995

23. Sheehan J, Kaptain G, Sheehan J, Jane J Sr: Congenital ab-sence of a cervical pedicle: report of two cases and review of the literature. Neurosurgery 47:1439–1442, 2000

24. Soleimanpour M, Gregg ML, Paraliticci R: Bilateral retroso-matic clefts at multiple lumbar levels. AJNR Am J Neuro-radiol 16:1616–1617, 1995

25. Wiener MD, Martinez S, Forsberg DA: Congenital absence of a cervical spine pedicle: clinical and radiologic findings. AJR Am J Roentgenol 155:1037–1041, 1990

26. Wortzman G, Steinhardt MI: Congenitally absent lumbar pedicle: a reappraisal. Radiology 152:713–718, 1984

27. Yousefzadeh DK, El-Khoury GY, Lupetin AR: Congenital aplastic-hypoplastic lumbar pedicle in infants and young children. Skeletal Radiol 7:259–265, 1982

DisclosuresThe authors report no conflict of interest concerning the materi-als or methods used in this study or the findings specified in this paper.

Author ContributionsDrafting the article: Hsieh. Critically revising the article: SH Lee. Administrative/technical/material support: HC Lee, Hsieh, Chen. Study supervision: HC Lee, SH Lee, Oh, Hwang, Park.

CorrespondenceHyung Chang Lee, Department of Cardiovascular Surgery, Wooridul Spine Hospital, Gimpo Airport, 70 Haneulgil, Gang-seo-gu, Seoul 155-823, Korea. email: drhclee@yahoo.com.

Unauthenticated | Downloaded 08/14/20 08:21 AM UTC