Identify unstable osteoporotic fractures with neurological impairment with a radiological instability score and treat them with minimally invasive percutaneous stabilization and vertebroplasty.
Thirty patients who had osteoporotic vertebral fractures with worsening back pain and neurologic impairment were included in the study. Charlson comorbidity index was used to assess the medical risk for a more extensive surgery. MRI, CT scan and plain radiographs of these patients were evaluated and seven spine instability signs were identified. A score of one was given for presence of one of these risk factors. These patients underwent minimally invasive percutaneous stabilization and vertebroplasty with or without decompression. Pre and post operative ASIA score, VAS scores were recorded. Cobbs angle, and anterior vertebral body height was recorded pre-operative and during each follow up.
There were 11 men and 19 women with a mean age of 71 years (range, 61–89). Sixteen patients had ASIA D, 10 had ASIA C and 4 had ASIA B. All of these patients had an instability score of ≥3. All these patients neurologically recovered, the VAS score for back pain significantly improved, and the spine was stable at one year follow up. Two patient required revision and extension of stabilization due to loosing of pedicle screws and recurrent instability.
Monitoring of spinal instability is essential in osteoporotic vertebral fractures. Presence of three or more instability signs is associated with worsening neurological outcome. These unstable fractures with neurologic impairment can be effectively treated with minimally invasive stabilization and vertebroplasty.
Most of the osteoporotic vertebral fractures heal well with conservative management with rest and bracing [
The purpose of this study is to evaluate the instability signs of osteoporotic compression fractures with neurodeficit and quantify them as an instability score. We also evaluated the efficacy of minimally invasive stabilization and vertebroplasty in these patients.
Between January 2016 and December 2019, thirty patients with thoracolumbar osteoporotic fractures with neurodeficit who underwent minimally invasive percutaneous stabilization (MIPS) combined with percutaneous vertebroplasty (PVP) with or without localized midline decompression. Electronic medical records of these patients were evaluated after approval from the ethical committee (IRB No: KDA01276). Charlson comorbidity index was used to assess the medical risk for a more extensive surgery. All patients were evaluated by computed tomography (CT), magnetic resonance imaging (MRI) and plain radiographs to determine the morphology of the fracture.
Clinical evaluation was done using VAS (visual analogue scale), and ASIA score done pre operatively, immediate post operatively, at 3 and 12 months. All patients were non ambulatory due to severe pain and neurologic impairment. They had bone mineral density (BMD) of more than 2.5 SD below the young adult mean (–2.5 SD or lower). Patients less than 65 years in age, patients with pathological fracture, osteomyelitis and patients with normal T score for BMD were excluded from the study.
Extensive literature search was done to find out factors that predict worsening in osteoporotic fractures. Authors found seven important factors that need to be observed in these patients. All patients were evaluated before the surgery by plain radiographs, CT and MRI to determine the presence of these risk factors. A score of 1 was given for the presence of each of these parameters. After surgery the patients had serial radiographs to assess alignment, screw loosening and implant failure.
Patients who had middle column involvement at presentation. These patients have a tendency to progress to non union and collapse of the vertebral body leading to spinal canal compression [
The condition of affected vertebrae was evaluated for the intravertebral air or intervertebral fluid or both. Intraverterbal fluid was area of hypointensity on the T1 weighted images and hyperintensity on T2 weighted images on MRI. Intervertebral air was area of hypointensity on T1 and T2 weighted images [
Was calculated on the Cobb angle between the cranial end plate of vertebra just proximal to the fracture and the caudal endplate of the vertebra just distal to the fractured vertebrae on lateral plain X-ray films [
Migration of the posterior vertebral elements into the spinal canal was categorized as retropulsion of the vertebral body [
Involvement of the posterior interspinous ligaments at initial injury or gradual failure of the posterior ligaments with progressive kyphosis was regarded as tri column involvement. Injury to these structures can lead to progession of deformity [
More than one compression fractures was included as a risk factor. This results in increase in deformity with worsening neurology.
The anterior vertebral height of the fractured vertebrae was compared to the normal vertebrae above. This leads to worsening sagittal profile. The height restored after surgery was also measured [
The spinal instability was calculated by adding these seven radiographic parameters with a score of one given for presence of each risk sign. These patients had 3 or more risk factors seen radiologically at presentation. Hence authors of this study considered a score of 3 or more as an unstable for this group of patients. Total score was divided into two categories of stability: stable (0–2) and unstable (≥3) (
Patient is postioned prone on bolsters. This leads to partial correction of kyphosis and restoration of anterior vertebral height. At first the pedicles of the affected segment were identified and skin was marked. The entry points for the percutaneous guide wires were made based on the C arm. Jamshedi needles were passed in to the pedicle after the position was confirmed on the image intensifier. Percutaneous screws were passed one level above and one level below the fracture over guide wire. In patients with higher angle of kyphosis screws were placed 2 levels above and below the fracture. In patients with severe osteoporosis they were augmented with bone cement. Two vertebroplasty needles were also passed in the fractured vertebra (Biportal Vertebroplasty). Position confirmed and about 4–6 mL of vertebroplasty cement was injected under fluoroscopy until cement reached the posterior 1/3rd of the vertebral body. Once the position of the cement was confirmed midline decompression was done at the level of retropulsion if necessary. In the current series midline decompression was done in 6 patients who retropulsion and canal encroachment of >50%. Midline incision was taken, paraspinal muscles retracted to expose the lamina. Partial laminectomy and decompression was done. When we stabilize and correct the kyphosis with rods the retropulsion decreases resulting in indirect decompression. The patients were mobilized on post-operative day one with braces in presence of physiotherapist.
The clinical and radiological evaluation were done pre operative, immediate post operative, 3 months and 1 year after surgery. The severity of the neurologic deficits was assessed using ASIA (American spinal injury Association) impairment scale. The pain intensity was recorded using the visual analogue scale (VAS). Focal kyphosis, vertebral body height and hardware loosening or implant failure were assessed at follow up.
Comparison of pre and post-operative measurements was performed using t-test for independent samples. Statistically significant differences were defined at a 95% confidence level. The values were given as mean±SD. The SPSS software was used for statistical evaluation.
Electronic medical records of a total of 30 patients were evaluated clinically and radiologically. The most common level involved was D12 followed by L1. These patients had failed average conservative trial of 9 weeks (range, 8–14 weeks) before they presented to us with neurodeficit. There were 11 men and 19 women with a mean age of 71 years (range, 61–89 years). The average Charlson comorbidity index was 4 (range, 2–5). The average duration of surgery was 130 minutes (110–180 minutes) and the mean blood loss was 80 mL (range, 60–300 mL). Single level (one above and one below) minimally invasive stabilization was done in 26 patients while two levels (2 above and 2 below) were done in 4 patients with higher degree of kyphosis. In 6 patients cement augmented pedicle screws were used to augment the stabilization. The mean follow up was 28 months (range, 20–36 months) and the average hospital stay was 4 days (3–8 days). There was no perioperative complications, infection or death. The VAS significantly dropped from average pre-operative 9 (range, 7–10) to 2 (range, 1–4) immediately after surgery and 1 (range 0–1) at 1 year follow up (p<0.001). Burst fracture with middle column involvement was seen in 14 patients. Vacuum sign was seen in 26 patients. Retropulsion and more than 25% spinal canal encroachment was seen in 26 patients. The average local angle of kyphosis was 18° pre operatively (range, 12°–30°) which decreased to 6° post operatively (range, 0°–14°) (p<0.001). Single level vertebral collapse was seen in 25 patients, 3 patients had 2 level vertebral collapse and 2 patients has 3 level vertebral collapse. Injury to posterior spinal ligaments was seen in 14 patients. Nine patients had posterior ligament injury at the time of fall. Posterior column injury as a result of stretch injury to posterior ligamentous structures due to progressive increase in kyphosis was seen in 5 patients. Greater than 50% vertebral height loss was seen in 20 patients. The average pre operative anterior vertebral body height was 12 mm (range, 5–20 mm) which increased to average post operative anterior vertebral height of 20 mm (range, 12–27 mm) (p<0.001). In the current series, a varied neurological deficit at presentation was seen. Sixteen patients had ASIA D, 10 had ASIA C and 4 had ASIA B. Improvement in neurological status was observed in all these patients. At 3 months follow up 4 patients improved from ASIA B to ASIA D, 10 improved from ASIA C to ASIA E and 16 patients improved from ASIA D improved to ASIA E. There was loosing of hardware seen in 2 patients at 1 year follow up which required revision to longer instrumentation. The was some loss of correction at one year follow up with angle of kyphosis increasing from average 6° to 12° (range, 0°–16°)at one year follow up.
Osteoporotic vertebral fractures lead to debilitating pain necessitating prolonged bed rest and increase in morbidity and mortality [
As in case of traumatic vertebral fractures in young patients, where treatment is been well established, strategies are unclear for vertebral fractures in elderly population [
The study is not without limitations. The study has small sample size and is retrospective in nature. The entire scoring system was based on individuals who received a surgical intervention. A prospective study to see the natural progression of the osteoporotic fractures would answer these questions regarding the instability more effectively. It would be ideal to identify these risk factors at the onset and prevent the progression of instability. The scoring system needs to be validated. Through this study the authors wish to highlight the instability factors in osteoporotic vertebral fractures which can potentially risk progression and worsening of neurology.
The prediction of late neurologic deficit, progression of kyphotic deformity in vertebral compression fractures is difficult. Prolonged monitoring is necessary in vertebral compression fractures. Minimally invasive stabilization with or without local decompression and vertberoplasty is well tolerated in the elderly population with encouraging results. We concluded that patients with osteoporotic vertebral fractures who had 3 or more risk factors were at a risk of failure of conservative treatment. If the prognosis can be predicted on the early stage more aggressive and better treatment options can be considered to prevent neurological involvement.
No potential conflict of interest relevant to this article.
A 78-year-old wheelchair bound female with ASIA C neurology. (A, B) Vaccum sign+, local kyphosis of 24°, anterior vertebral height loss of >50%, retropulsion and spinal canal encroachment 7>25% (instability score 4). (C) Guide wires and biportal vetebroplasty needles placed. (D) Vertebroplasty and minimally invasive stabilization with cement augmented percutaneous pedicular screws.
A 68-year-old male ASIA D Incomplete Burst #. (A, B) Incomplete burst # with retropulsion and posterior ligamentous injury (instability score 3). (C, D) Navigation guided MIS stabilization and D9 vertebroplasty.
An 82-year-old male with ASIA D neurology. (A, B) Imaging s/o Figure 1 and 2: Vaccum sign+, local kyphosis of 30°, anterior vertebral height loss of >50%, retropulsion and spinal canal encroachment >25% (instability score 4). (C) MIS stabilization and vertebroplasty.
Patient demographics and clinical data
Sr. No. | Age (yr) | Sex | Charlson comorbity index | Level | ASIA grade Preop | ASIA grade at 3 mo | Preop VAS for back pain | Postop VAS score |
---|---|---|---|---|---|---|---|---|
1 | 70 | F | 4 | #D10 | C | E | 9 | 3 |
2 | 84 | F | 5 | #D12 | C | E | 8 | 3 |
3 | 61 | F | 3 | #D12 | D | E | 8 | 2 |
4 | 78 | F | 4 | #D12 | C | D | 7 | 2 |
5 | 77 | F | 5 | #D12 | D | E | 8 | 2 |
6 | 72 | F | 5 | #D12 | C | E | 8 | 4 |
7 | 61 | F | 2 | #D9 | D | E | 9 | 2 |
8 | 62 | F | 2 | #L1 | D | E | 8 | 3 |
9 | 63 | F | 2 | #L1 | D | E | 9 | 3 |
10 | 64 | F | 2 | #L2 | D | E | 8 | 1 |
11 | 65 | F | 2 | #D12 | C | E | 8 | 5 |
12 | 80 | M | 4 | #D12 | D | E | 7 | 3 |
13 | 81 | M | 3 | #D12 | C | E | 9 | 0 |
14 | 74 | M | 3 | #L1 | D | E | 9 | 1 |
15 | 75 | F | 4 | #L1 | C | E | 10 | 4 |
16 | 75 | M | 4 | #L4 | C | E | 10 | 1 |
17 | 74 | F | 4 | #L2 | B | D | 10 | 4 |
18 | 81 | M | 5 | #L1 | D | E | 9 | 2 |
19 | 68 | F | 4 | #L2 | D | E | 10 | 0 |
20 | 74 | F | 4 | #D12 | D | E | 9 | 0 |
21 | 67 | F | 3 | #D12 | B | D | 10 | 4 |
22 | 67 | F | 2 | #L1 | C | E | 10 | 1 |
23 | 75 | M | 4 | #L1 | D | E | 10 | 0 |
24 | 75 | F | 4 | #L1 | B | D | 9 | 2 |
25 | 82 | M | 5 | #D12 | C | E | 9 | 0 |
26 | 65 | M | 2 | #L1 | B | D | 9 | 3 |
27 | 67 | F | 3 | #L2 | D | E | 10 | 0 |
28 | 69 | M | 4 | #L3 | D | E | 10 | 3 |
29 | 66 | M | 3 | #L1 | D | E | 10 | 0 |
30 | 68 | M | 3 | #L1 | D | E | 10 | 0 |
Risk factors for osteoporotic vertebral fractures
Serial No. | Spine at risk sign | Score |
---|---|---|
1 | Incomplete burst fractures (middle column involvement) |
1 |
2 | Vacuum sign | 1 |
3 | Local kyphosis of more than 20 degrees | 1 |
4 | Retropulsion/spinal canal encroachment of more than 25% | 1 |
5 | Posterior ligament injury | 1 |
6 | Multiple wedge compression fractures | 1 |
7 | Anterior vertebral height loss of >50% | 1 |
Radiological parameters in these patients
Sr No. | AOK Preop | AOK Postop | Incomplete burst # | VS | CE in % | PLC injury | Multiple comp # | >50% VBH loss |
---|---|---|---|---|---|---|---|---|
1 | 15 | 5 | 0 | 1 | 25 | 0 | 0 | 1 |
2 | 10 | 18 | 1 | 1 | 30 | 1 | 1 | 0 |
3 | 10 | 10 | 1 | 1 | 15 | 0 | 1 | 1 |
4 | 20 | 15 | 0 | 1 | 40 | 1 | 0 | 0 |
5 | 0 | 16 | 1 | 1 | 30 | 0 | 0 | 1 |
6 | 0-5 | 20 | 1 | 1 | 35 | 0 | 0 | 1 |
7 | 20 | 20 | 0 | 1 | 15 | 0 | 0 | 1 |
8 | 10 | 0 | 1 | 1 | 15 | 0 | 0 | 1 |
9 | 20 | 5 | 0 | 1 | 20 | 0 | 0 | 1 |
10 | 20 | 5 | 0 | 1 | 15 | 0 | 0 | 1 |
11 | 0 | 0 | 1 | 1 | 35 | 0 | 0 | 0 |
12 | 0 | 0 | 1 | 1 | 15 | 0 | 0 | 0 |
13 | 10 | 0 | 0 | 1 | 20 | 0 | 0 | 0 |
14 | 10 | 0 | 1 | 1 | 25 | 0 | 0 | 0 |
15 | 30 | 10 | 1 | 1 | 40 | 1 | 1 | 1 |
16 | 10 | 0 | 1 | 0 | 30 | 1 | 0 | 1 |
17 | 20 | 10 | 0 | 1 | 40 | 1 | 1 | 1 |
18 | 20 | 10 | 0 | 1 | 30 | 1 | 0 | 1 |
19 | 15 | 0 | 0 | 1 | 10 | 1 | 0 | 1 |
20 | 30 | 10 | 0 | 1 | 30 | 0 | 1 | 1 |
21 | 30 | 25 | 0 | 1 | 30 | 0 | 1 | 1 |
22 | 26 | 20 | 0 | 1 | 30 | 0 | 1 | 1 |
23 | 0 | 0 | 1 | 0 | 20 | 1 | 0 | 0 |
24 | 30 | 10 | 0 | 1 | 40 | 0 | 1 | 0 |
25 | 30 | 10 | 0 | 1 | 30 | 0 | 1 | 0 |
26 | 30 | 10 | 0 | 1 | 40 | 0 | 1 | 0 |
27 | 15 | 0 | 0 | 1 | 10 | 1 | 0 | 1 |
28 | 15 | 0 | 1 | 1 | 25 | 0 | 0 | 1 |
29 | 0 | 0 | 1 | 0 | 20 | 1 | 0 | 1 |
30 | 10 | 0 | 1 | 0 | 25 | 1 | 0 | 1 |
AOK: angle of kyphosis, VS: vacuum sign, CE: canal encroachment, #: fracture, PLC: posterior ligament complex, VBH: vertebral body height.