Acute burst fracture in Kummell’s disease with acute onset neurological deficit: a case report on role of spinal stability and technical notes on “pivot ligamentotaxis”

Background Kummell’s Disease has insidious progression. Neurological deficit is usually slow in onset and progression and only few cases of acute neurological deficit have been reported. We came across a case of Kummell’s disease which progressed to burst fracture, developed neurological deficit within two weeks. We managed patient with “pivot ligamentotaxis” and Polymethylmethacrylate augmented, posterior compressed, short segment percutaneous pedicle screw fixation. Case presentation Eighty-three years old woman following fall was on conservative management at another hospital. She had no neurological deficit. A week later her back pain aggravated and two weeks later developed bilateral buttock pain, bilateral lower limb weakness and diminished sensation in the sacral area. Radiological investigations (X-rays, Magnetic resonance imaging and Computed tomography) showed L1 vertebral body fracture with vacuum cleft and fracture fragment retropulsed into the spinal canal. A diagnosis of Kummell’s disease with burst fracture of L1 vertebra & neurological deficit was made. Patient was managed with Polymethylmethacrylate augmented, posterior compressed, short segment percutaneous pedicle screw fixation. The reduction of the retropulsed fragment was achieved by virtue of “Pivot ligamentotaxis”. The patient got relieved of the symptoms (Preoperative VAS 8 and postoperative VAS 3) and was allowed brace assisted ambulation on first postoperative day. Conclusion This study reports acute occurrence of the burst fracture in unstable vertebra inflicted by Kummell’s disease and role of spinal stability in recovery. We achieved closed reduction of the fracture fragments and relief of the cord compression by posterior compression with “pivot ligamentotaxis”.


Background
The osteoporotic vertebral compression fractures and Kummell's disease (KD) have become common [1,2]. Kummell's disease is a disease caused by osteonecrosis and can lead to severe vertebral collapse, which can lead to severe pain and may progress to neurological deficit [1,3]. Neurological deficit in KD usually progresses slowly. Two cases of acute neurological deficit in KD have been reported [4,5]. We report a case with acute occurrence and progression of neurological deficit in early phase of KD associated with burst fracture of the vertebral body which was managed by reduction using "pivot ligamentotaxis" and Polymethylmethacrylate augmented posterior compressive, short segment percutaneous pedicle screw fixation. The neurological status was restored after stabilization.

Case History
Eighty-three years old woman following a fall was put on conservative management at another hospital. Initially her physical examination was mostly normal other than spinal tenderness and she had no neurological (Sensory or motor) deficit. A week later she started having severe back pain and two weeks later she also developed bilateral buttocks pain, bilateral lower limb weakness and had diminished sensation in the sacral area.

Physical Examination
Revealed severe tenderness at thoracolumbar junction and neurologic examination demonstrated grade 4/5 strength in the lower extremities. Sacral sensation decreased, bladder and bowel function was intact.

Investigations
Initial magnetic resonance imaging (MRI) revealed vertebral compression fracture of L1 body without burst and no canal compromise (Figs. 1a & 2a). One week later the MRI and computed tomography (CT) revealed compression fracture with intravertebral cleft and beginning of the burst of the vertebral body. A fragment was retropulsed into the canal (Figs. 1b, b2, and 2b). An MRI two weeks from initial fall shows aggravation of the burst fracture and thecal sac compression (Figs. 1c & 2c). A diagnosis of Kummell's disease at L1 vertebra with burst fracture of the body with spinal canal compromise and neurological deficit was made.

Pivot Ligamentotaxis
Is a novel concept in minimally invasive spine surgery (MISS). In our case the left pedicle screws of the T12, L1 & L2 were inserted first followed by the right screw of the L1 vertebra. Using the inserter the rod was slide through the pedicle screws on right side. Rod blockers of T12 pedicle screw was tightened first then T12 & L1 pedicle screws compressed and with the help of the compressor placed horizontally a cranially distractive force applied using left L1 pedicle screw as pivot points and the rod blockers of the right L1 pedicle screw tightened. This maneuver is repeated with of L1 and L2 where a caudally directed distractive force was applied using L1 pedicle as pivot. The cumulative result of this maneuver was ligamentotaxis and reduction of the retropulsed fragment Figs. 1d, 2d, and 3a & b). This was followed by insertion of remaining two contralateral pedicle screws and fixation. As described earlier all the screws were PMMA augmented inserted using minimally invasive screw insertion technique.

Discussion and conclusion
Not many cases of Kummell's disease associated with neurological deficit have been reported and a few reports of KD patients who presented with early onset and acute neurological deficit [4,5]. However, we could not find  any study or case report which mentions acutely occurring burst fracture of the involved vertebra as inciting event for the neurological compromise.
The dynamic instability at the vertebral body fracture adversely affects the fracture union, promotes vascular compromise which may result into psuedarthrosis and osteonecrosis [1,2,6]. Thus spinal instability has a role to play in the progression of the Kummell's disease a fact supported by our study. Kim et al. had proposed Spinal Instability Predictive Score (SIPS) for KD patients with vertebroplasty which scores and grades instability [2]. There is no such score to predict the progression from osteoporotic vertebral fracture to the Kummel's disease.
Various surgical modalities are summarized in comprehensive review by Formica M et al. [1]. Laminectomy, and hematoma removal mentioned for neurological deficit associated with intraspinal hematoma [4,5]. Bone cement augmented percutaneous pedicle screw stabilization also has good results in Kummell's disease [7,8].
We performed PMMA augmented, posterior compressed, percutaneous short segment pedicle screw fixation (PA-SSPPF) involving T12, L1, L2 vertebrae. The patient improved rapidly in postoperative period with the magnetic resonance imaging (MRI) showing resolution of canal compromise. Fast recovery of the patient can be attributed to the spinal stability achieved following fixation. We could reduce the fracture fragments into place and relieve thecal sac compression by applying posterior compression. This reduction was possible due to pivoting around the contralateral pedicle and we name this phenomenon as "pivot ligamentotaxis". The pivot ligamentotaxis converts compression applied posterior into ligamentotaxis forces in the ligaments anterior to the facet joints e.g. posterior longitudinal ligaments (PLL) and anterior longitudinal ligaments (ALL) by virtue of pivoting around the facet joints.
This study shows that the neurological status can deteriorate rapidly following burst fracture of the involved vertebral body. The expeditious deterioration and prompt recovery of the patient affirms the role of spinal stability in the pathogenesis of burst fracture in KD and neurological deficit. "Pivot ligamentotaxis" allowed us to achieve closed reduction of fracture and decompression of the thecal sac. However, a study with larger sample and longer follow up would be required to derive a significant conclusion. In addition, the concept of "pivot ligamentotaxis" needs further evaluation with biomechanical studies. Also there is need for a predictive scoring system which could predict the possibility of progression of vertebral compression fracture to Kummell's disease and occurrence of burst fracture at the earliest stage, so that appropriate measures could be taken. No funds were received in support of this study. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Availability of data and materials All data generated or analyzed during this study are included in this published article (and its supplementary information files).

Authors' contributions
All the authors have contributed significantly to the concept, design, data acquisition & analysis and drafting the manuscript for this work. All the authors have given final approval for the article to be published and have agreed to be accountable for all aspects of the work. All the authors satisfy the ICMJE criteria for authorship. HSK is the corresponding author and has contributed significantly to the concept, design, data acquisition & analysis and drafting of the manuscript for this work. He has also given final approval of the version to be published. RS has contributed significantly to the concept, design, data acquisition & analysis and drafting of the manuscript for this work. NMA has contributed significantly to the concept, design, data acquisition & analysis and drafting of the manuscript for this work. SWO has contributed significantly to the concept, design, data acquisition & analysis for this work. JHN has contributed significantly to the concept, design, data acquisition & analysis for this work. JHP has contributed significantly to the drafting the work or revising it critically for important intellectual content. ITJ has major contribution to the conception or completion of the manuscript. SHO has major contribution to the conception or completion of the manuscript.

Ethics approval and consent to participate
The patient had consented in written for participation in the study with prior approval of the Nanoori Hospital's human research ethics committee.

Consent for publication
The patient had consented in written for the publication of the case report along with participant's data in any form (including images).