2019 Volume 6 Issue 1 Pages 35-37
In rare cases, pedicle fracture is associated with spine surgery, spondylolysis, or stress fracture. We report a patient without trauma whose bilateral lumbar pedicle fracture was detected incidentally. A 67-year-old woman reported leg numbness and pain. Lumbar MRI showed spinal canal stenosis at the L4/L5 level. Drug treatment was only partially effective. A lumbar computed tomography (CT) scan performed 3 months later revealed bilateral pedicle fracture at L4. A second lumbar MRI showed fresh bilateral L4 pedicle fracture that was not observed on the first scan. Due to the presence of osteoporosis we prescribed daily teriparatide and the wearing of a lumbo-sacral corset. Her subsequent clinical course was uneventful and the fractures fused under conservative treatment. During this period, she had no low back pain (LBP). Only 12 earlier patients with spontaneous bilateral pedicle fracture without trauma, spinal surgery, or bone abnormality have been reported. In 8 patients, including ours, the fracture level was at L4. In all except our patient, LBP was the most common symptom. Pedicle fracture as detected incidentally in our patient. Of the 13 patients, 4 were physically active adolescents; of the 9 others, 5 were women with osteoporosis. Our case is the first report of incidental spontaneous bilateral pedicle fracture.
In rare cases, pedicle fracture is associated with spine surgery, spondylolysis, or stress fracture; patients usually report low back pain (LBP). There are few reports on the characteristics and treatment of pedicle stress fractures. We report a rare patient who had not suffered trauma or LBP and whose idiopathic bilateral lumbar pedicle fracture was detected incidentally. We also present a literature review.
This 67-year-old woman had suffered no earlier trauma, accidents, or spinal surgery but had a 1-year history of leg numbness, leg pain, and intermittent claudication. She reported no motor weakness, bowel or bladder symptoms, or LBP. Lumbar magnetic resonance imaging (MRI) revealed lumbar spinal canal stenosis (LSS) at L4/L5 (Fig. 1). We attributed her symptoms to LSS and prescribed prostaglandin e1, non-steroidal anti-inflammatory drugs, and pregabalin. Because her symptoms persisted despite slight improvement, we performed lumbar computed tomography (CT) 3 months after the first MRI study for surgical planning (Fig. 2). Unexpectedly, it revealed bilateral pedicle fracture at L4. Dynamic radiography denied instability. A second lumbar MRI study (Fig. 1) demonstrated hypointensity at the L4 pedicle; it had not been recognized on the earlier MRI scan. There was no signal change in the other region, such as vertebral body, intervertebral disc, and facet joint. Our diagnosis was fresh bilateral pedicle fracture.
First lumbar MRI scans showing lumbar canal stenosis without pedicle fracture. (A) T2-weighted image (sagittal view). (B and C) T1-weighted images (sagittal view). B = right side, C = left side. The 2nd lumbar MRI scans shows bilateral pedicle fracture at L4. (D and E) T1-weighted images (sagittal view). D = right side, E = left side. (F) T1-weighted image (axial view at L4).
First lumbar CT scans at the level of L4 showing bilateral pedicle fracture. (A) Axial view. (B) Sagittal view (right side). (C) Sagittal view (left side). Lumbar CT scans obtained 4 months later showing fracture healing at L4. (D) Axial view. (E) Sagittal view (right side). (F) Sgittal view (left side).
Upon careful inquiry she reported no LBP but stated experiencing a slight tic one month earlier when she twisted her body to remove baggage from a narrow space. There was no other pain then or subsequently. Her bone mineral density was 0.576 g/cm2 at the proximal femur. We attributed her bilateral pedicle fracture to osteoporosis and prescribed daily teriparatide and the wearing of a lumbo-sacral corset.
Her subsequent clinical course was uneventful, her leg symptoms gradually improved, and the fractures fused spontaneously under conservative treatment (Fig. 2).
Spontaneous bilateral pedicle fracture of the lumbar spine without trauma is rare. Its etiology is unknown but may be related to stress fracture. Cadaver studies revealed that the pars interarticularis is most prone to stress fracture in the vertebral bone and that the pedicle is the second-weakest vertebral area.1) Spontaneous lumbar pedicle fracture occurs less often in the neural arch than spondylolysis; it can be associated with spinal surgery because, especially after spinal fusion, the pedicle may be subjected to increased forces.2)
Only 12 patients with spontaneous bilateral pedicle fracture without previous trauma, spinal surgery, or bone abnormality have been reported (Table 1).3–14) The fracture level was at L4 in 8 patients, including ours. Spontaneous bilateral pedicle fracture differs from spondylolysis; stress fracture at the pars interarticularis is seen most often at L5.1) The average age of the patients reported by others was 43.4 years; 4 (3 females, 1 male) were physically active adolescents3,8,11,14) and all 12 reported LBP. Of the older patients, 5 manifested osteoporosis possibly related to their spontaneous stress pedicle fracture. Our 67-year-old patient did not suffer LBP; her symptom was intermittent claudication due to LSS. This is the first reported case of incidentally-detected idiopathic bilateral pedicle fracture.
| Reference | Age | Sex | Symptom | Activity level | Level | Osteoporosis | Fracture stage | Conservative treatment | Operation | Fracture union |
|---|---|---|---|---|---|---|---|---|---|---|
| Ireland8) | 18 | F | LBP | Ballet dancer | L2 | – | Early | Rest | – | – |
| Traughber14) | 16 | F | LBP | Unknown | L5 | – | Early | Rest | – | + |
| Amari3) | 14 | M | LBP + LP | Ballet dancer | L4 | – | Early | Corset | – | + |
| Parvatneni11) | 19 | F | LBP | College lacrosse | L5 | – | Progressive | Corset | + | + |
| Sadiq12) | 36 | F | LBP | Sedentary-minimal physical activity | L2 | – | Terminal | Only pain control | – | – |
| Hajjioui6) | 54 | F | LBP | Unknown | L4 | + | Terminal | Only pain control | – | – |
| Kim10) | 70 | F | LBP + LP | Unknown | L4, L5 | + | Terminal | – | + | + |
| Schmid13) | 60 | F | LBP + LP | Unknown | L2, L3, L4 | – | Progressive | – | + | + |
| Ha2) | 50 | F | LBP + LP | Unknown | L5 | Unknown | Early | – | + | + |
| Doita 20094) | 77 | F | LBP + LP | Unknown | L4 | + | Early | – | + | + |
| Diota 20085) | 57 | M | LBP + LP | Unknown | L4 | Unknown | Early | – | + | + |
| Johnson9) | 50 | F | LBP + LP | No strenuous activities | L4 | + | Progressive | Corset | + | + |
| Our case | 67 | F | LP | No strenuous activities | L4 | + | Early | Corset | – | + |
F: female, M: male, LBP: low back pain, LP: leg pain.
Spontaneous bilateral pedicle fracture may be a condition similar to spondylolysis, which can be addressed conservatively in the early stage. On CT images, patients with spondylolysis manifest fissures (early stage), fractures identified as a narrow gap or round-edged lesions (progressive stage), and pseudarthrosis (terminal stage).15) Of the 12 previously-reported patients with spontaneous bilateral pedicle fracture, 2 were treated by rest and 3 by external fixation. Conservative treatment was successful in 2 adolescents in the early stage.3,14) Fusion surgery was performed in 7 patients; 2 of these were in the progressive stage and conservative therapy with external fixation had failed.9,11) In our elderly patient, conservative treatment resulted in spontaneous healing of the early-stage fracture. The early discovery of pedicle fracture may result in successful conservative treatment even in older individuals.
All authors have no conflict of interest.
