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Thoracolumbar Spinal Injuries – Evolution of Understanding of fracture Mechanics and Management Options

Volume 1 | Issue 2 | Sep – Dec 2016 | Page 7-8 | Shailesh Hadgaonkar, Ketan Khurjekar


Authors : Shailesh Hadgaonkar [1], Ketan Khurjekar [1]

[1] Sancheti Institute for Orthopaedics &Rehabilitation, Pune, India.

Address of Correspondence
Dr Shailesh Hadgaonkar
Sancheti Institute for Orthopaedics &Rehabilitation, Pune, India
Email: editor.ijspine@gmail.com


Introduction

This symposia on thoracolumbar fractures is aimed at providing an overview to the reader with respect to evolving trends in fracture diagnosis and management.
There has always been controversies in treating thoracolumbar spine injuries with neurological deficit, but as we know the goal of managing these T-L junction injuries is to maintain the sagittal alignment for mechanical stability and to give additional support for rehab and physiotherapy for neurological recovery. The main aim of thoracolumbar fracture surgery is to give structural support to the spinal column for wheelchair mobilization in cases with complete injury and paraplegia. We have found significant improvement in quality of life in patients who were operated for these severe thoraco lumbar spinal injuries. As we all know the most common level of these injuries is T 12 and L1, sustaining from the high velocity trauma. The flexibility at thoraco lumbar junction, the thoracic rib cage ending at the junctional level, coronal alignment of facet joint in thoracic spine and the changes in the lower thoracic facets to less coronal alignment is likely to cause fracture dislocations. Various transitional zone injuries- between T 11- L2 are approximately 50 – 60 % of all injuries. Most common reason for these injuries – are fall from height and high velocity RTA. There is a significant association of other injuries such as chest, abdominal, vascular injuries and also head injuries with these fracture dislocations.
It is paramount to evaluate these patients in detail, thorough clinical and neurological assessment is mandatory. The standard American Spinal Injury Association (ASIA) guidelines should be followed in neurological assessment. Associated relevant investigations as the X-rays and MRI scans will guide for non-operative Vs operative management. Additional modalities such as CT scans and 3D reconstruction is important clinically unstable and high grade T-L injuries. Primary assessment and medical management is important to stabilize the patient before planning the surgery.

Evolution of classification systems :
Various different classification system have evolved from the World War I and II days, as Bohler in 1930 classified T-L fractures into five categories :-
1- Compression fractures
2- Flexion /distraction injuries
3- Extension fractures
4- Rotational injuries
5- Shear fractures
Watson Jones in 1938 classified T-L injuries adding instability to Bohler’s classification. The most important factor in Watson Jones classification was description of Posterior ligamentous complex (PLC) in spine stability, as they felt the integrity of interspinous ligament is most important stability factor.
Nicole in 1949, further classified using anatomical classification with emphasis on interspinous ligament integrity. He described the stability structures as the vertebral body, disc, intervertebral joint, and interspinous ligament. This classification serves as a foundation for subsequent classifications.
Holdsworth in 1963, described Two column theory and he emphasized the spinal stability on posterior ligamentous complex (PLC) stability. Kelly and Whitesides attempted to modify Holdsworth classification, as they specifically mentioned anterior column as solid vertebral body whereas posterior column as posterior elements and neural arch. Also they emphasized the treatment of neurological deficit.
Dennis in 1983, came up with a new concept – Three column theory using the radiological parameters. He provided a new insight in detailing the classification into anterior, middle and posterior column. They described the middle column – osteo-ligamentous complex injury is the primary determinant of mechanical spinal stability.
Mcafee et al described the classification based on CT scans of 100 consecutive patients and divided into 6 groups. This was the most detailed classification system in the 1980’s. They described the height loss of vertebral body, facetal joint subluxation, fragments in the spinal canal, progressive neurological deficit, kyphosis angle because of instability was assessed with the CT scan. As per their criteria translational and flexion/rotational fracture dislocation and posterior ligamentous complex (PLC) injury with kyphosis more than 30 degrees angle should undergo surgery.
In 1994 Mc Cormack classified on load sharing concept, which focuses more on location of the fracture in the vertebral body.
Then in 1994, Magrel et al came up with classification based on evaluation of 1445 cases and classified into 3 types and 53 injury models.
In 2005, Vaccero et al came up with Spine trauma study group – Thoraco Lumbar Injury Classification System (TLICS) which takes a detail note on fracture mechanism, the intact PLC status and the neurological status of the patient.
TLICS points:
Fracture Mechanism
Compression fracture 1
Burst fracture 1
Rotational fracture 3
Splitting 4
Neurological involvement
None 0
Nerve root 2
Medulla spinalis, conus medularis-
– Incomplete 3
– Complete 2
Cauda equina 3
Posterior ligamentous complex
Intact 0
Possibly injured 2
Injured 3

Surgical indication is for cases with 5 points or more, cases with 4 points are between surgical vs non surgical, and cases with 3 or less points are non surgical. It is quite a comprehensive and popular classification in clinical practice and many centers prefer to use this classification worldwide.
Recently AO Spine knowledge forum has proposed a comprehensive modified AO classification based on morphology of fracture, neurology status and description of relevant patient specific modifiers
These classifications signify the growth in our understanding of pahtomechanics of the spine fracture as well as takes into account our growing expertise in the offering better surgical options to the patients.

Management Options:
Various management options are discussed in the current symposia and most of the options are individualised depending on the etiology and extent of fracture. Few general rules are noted below –
– Cases where there is retropulsion up to 40- 50 degrees without neurological deficit with intact PLC we can attempt indirect decompression and distraction in first 5 -6 days after the injury.
– Cases with less angulation and wedging with minimal kyphosis can be dealt with short segment fixation.
– Interlink in long construct always adds-up to the stability. Reduction of the dislocation with various maneuvers always beneficial for sagittal profile.
– Role of steroid is controversial post T-L injury with neurological deficit and is rarely used worldwide.
– Role of minimally invasive spine (MIS) surgery is evolving and needs a longer follow up. MIS surgery helps in reducing the bleeding, morbidity in selective cases.
– There is a significant role of rehabilitation post-surgery, in cases of T-L fractures with neurological deficit. Stem cells are promising in animal and Fish models in research labs and we are very hopeful about the same in humans.
Most of the above options are discussed in details in the symposia and we would encourage the readers to go through the articles. Ultimately the clinical evaluation summed with the radiological parameters will decide the management plan as cases with instability, neurological deficit and progressive neurological worsening cases will need surgical intervention. A lot of cases can be conserved with careful monitoring.
We thank all the authors and contributors for participating in the symposia and invite interested readers to participate as symposium editors or authors. Please write to us by email and provide your suggestions and comments.


How to Cite this Article: Hadgaonkar S, Khurjekar K. Thoracolumbar Spinal Injuries Evolution of Understanding Fracture Mechanics and Management Options . International Journal of Spine Sep-Dec 2016;1(2):7-8.


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Management Strategies and Selection of Fusion Levels in Adult Spinal Deformities

Volume 1 | Issue 1 | Apr – June 2016 | Page 25-30|Kshitij Chaudhary[1], Ranjith Unnikrishnan[2].


Authors :Kshitij Chaudhary[1], Ranjith Unnikrishnan[2]

[1] Department of Spine Surgery, Mumbai, Maharashtra, India
[2] Kerala Institute of Medical Sciences, Trivandrum, Kerala, India

Address of Correspondence
Dr. Kshitij Chaudhary
206-3A, Vaishali nagar, KK Marg, Jacob Circle, Mahalaxmi East
Mumbai 400011.
Email: chaudhary.kc@gmail.com


Abstract

Abstract: Adult spinal deformity (ASD) is fast becoming a global spinal epidemic. Decision making in adult deformity is a complex process and with each passing year, the treatment protocols are evolving as new evidence comes to light. The decision to choose surgery is not only complex but also patient specific. The surgical options can be broadly classified into three groups in order of increasing complexity and surgical invasiveness: 1) focal decompression only, 2) decompression with limited fusion, and 3) fusion of the entire curve. Of the many controversies plaguing adult spinal deformity, choosing end levels of fusion is the subject matter of ongoing debate. This narrative review makes an attempt to provide general guidelines for selecting fusion levels based on the current evidence.
Key Words: Adult spinal deformity, surgery, degenerative scoliosis, fusion levels, review


Introduction
As the world’s population ages, adult spinal deformity (ASD) is fast becoming a global spinal epidemic. Although accurate estimates are difficult, the prevalence is reported to be as high as 60% in individuals older than 60 years [1]. Adult deformity can be of two types. Adult idiopathic scoliosis represents patients who have a history of idiopathic scoliosis in childhood that present with symptoms related to degenerative arthritis within the curve. Degenerative or De novo scoliosis represents patients without preexisting spinal deformity who present with spinal deformity secondary to degenerative spinal changes [2]. It is hypothesized that asymmetric disc degeneration and facet arthritis with lateral and/or rotatory listhesis is responsible for the development of de novo scoliosis in adults. Usually, the age of presentation of patients with degenerative scoliosis is in the 6th decade. The typical presentation is either axial back pain or radiculopathy (radicular or neurogenic claudication). With severe deformity, patients may present with a change in body habitus, abnormal posture and may complain of ill-fitting clothes. One of the fundamental difference between treating adolescent deformity and adult deformity is that the treatment choice is guided by the clinical presentation rather than radiological parameters. Although precise therapeutic guidelines for treating these patients are not defined, clinicians should take into consideration certain general evidence-based principles when treating these patients. Decision making in adult deformity is a complex process and with each passing year, the treatment protocols are evolving as new evidence comes to light. In general, with exception of patients presenting with acute neurological deterioration, nonoperative treatment is the first option offered to patients. The surgical options can be broadly classified into three groups in order of increasing complexity and surgical invasiveness: 1) focal decompression only, 2) decompression with limited fusion, and 3) fusion of the entire curve [3]. Surgery is indicated in patients who fail conservative care and continue have ongoing back pain, neurological symptoms or deformity progression. The decision to choose surgery is not only complex but also patient specific. Innumerable factors need to be considered before finalizing on surgery, and the patient should be part of this decision-making process. Of the many controversies plaguing adult spinal deformity, choosing end levels of fusion is the subject matter of ongoing debate. While limited fusion and decompression is associated with lower postoperative complications, these patients may soon become symptomatic due to adjacent segment degeneration if the fusion levels are not chosen wisely. Extensive fusion of the entire deformity not only carries a significant surgical risk, but is also associated with complications related to selection of end-levels of fusion. At the distal end the debate is whether to fuse or not to fuse to sacrum. At the proximal end, proximal junctional kyphosis remains a risk and, therefore, choice of upper end-level of fusion requires special attention. This review article makes an attempt to provide general guidelines for selecting fusion levels based on the current evidence.

Radiographic evaluation of ASD patient:
Standing full spine radiographs:
Standing radiographs are of paramount importance. Patients with spinal deformity should be evaluated using full spine radiographs that include the external auditory canal and the femoral heads. The position of the arms with 30º shoulder flexion has the least impact on sagittal alignment [4].
Frontal Radiograph
1. Cobb angle: measure for all curves, including fractional curves. Identify stable, neutral and end vertebrae.
2. Lateral listhesis: adjacent vertebrae are relatively neutral in relation to each other
3. Rotatory listhesis: cephalad vertebra is rotated compared to the caudad vertebra
4. Coronal balance: offset of the C7 in relation to the central sacral vertical line is measured, with offsets of more than 5 cm considered as abnormal.
5. Clavicle angle: angle between a line joining two clavicles (most cephalad points of both clavicles) and the horizontal reference line. It is a measure of shoulder imbalance.
6. Pelvic obliquity: angle between the highest points of iliac crest or sacral ala and the horizontal reference line. If there is a pelvic obliquity it is imperative to rule out an oblique take off of L5 and limb length inequality.

Lateral Radiograph
1. Thoracic kyphosis: as measured from T4 to T12. (Fig. 1)
2. Lumbar lordosis: as measured from L1 to S1. (Fig. 1)
3. Global Sagittal balance (Fig. 1): These parameters have been shown to correlate with self-reported pain and disability (HRQOL measures) [5,6].
a. Sagittal C7 plumbline is drawn from the centroid of C7. Measure the horizontal offset of from this plumbline and the posterior superior corner of S1.
b. T1 and T9 spinopelvic parameters: these are angles between the the vertical plumbline dropped from the center of T1 or T9 vertebral body and the line joining this center to the center of the femoral axis. These are a measure of sagittal imbalance.
4. Pelvic parameters (Fig 2): Pelvic incidence is a morphological parameter that remains relatively constant throughout adulthood. It is the sum of sacral slope and pelvic tilt (PI=SS+PT) which vary according to the pelvic position. Normative values are: 52º for PI, 12º for PT and 40º for SS [7].
5. Anterior or posterior vertebral subluxation.
6. Osteophytes and status of disc collapse: These are markers or stability of a particular motion segment

Figure 1

Adult spinal deformity classification:
Unlike the widely popular and established Lenke classification for adolescent idiopathic scoliosis, the classification systems for adult spinal deformity continue to evolve as increasing evidence accumulates. The attempt is to try to link the classification system to a treatment algorithm that can reliably predict the outcome of surgical intervention. The adult spinal deformity committee of the Scoliosis Research Society has developed the SRS-Schwab Adult Spinal Deformity classification that has been shown to be comprehensive and predictive of outcomes and complications in the management of ASD [8].
Flexibility films
When planning a surgery, it is important to assess the flexibility of the deformity. It is extremely useful to compare the standing radiographs with the supine films. Supplementary radiographs such as push-prone films, traction, and bending films may also be useful. Silva and Lenke have categorized curve flexibility into three categories: flexible, stiff and stuck. “Flexible” deformities will correct passively by at least 50% and will not require additional release procedures. “Stiff” deformities correct 25-50% and may require an anterior release or posterior facet resections (Ponte osteotomies). “Stuck” deformities are quite rigid and need three column osteotomy [3].

Figure 2

MRI and CT scan
MRI is useful to evaluate the spinal canal in patients with neurological symptoms. The location of spinal stenosis has important implications on surgical treatment. CT myelogram may be useful in patient with contraindications to MRI. In patient with severe deformity, multiplaner CT reconstruction may give more information compared to MRI. Osteophytosis and autofused segments are readily diagnosed on CT scan and this too has ramifications on surgical treatment.

Surgical options

1) Decompression without fusion:
Although this is an attractive option for the elderly with comorbidities, it can be successfully employed in only a subset of patients. It is ideal for a patient with neurological symptoms (radicular pain) with little or no back pain. The nature of stenosis should be either central canal or lateral recess, and it should be possible to perform a limited decompression to achieve nerve decompression. Foraminal stenosis requires wider destabilizing bony resection and is usually not suitable for decompression only procedure. Besides, if the comparison between standing and supine films suggest a collapsing nature of the deformity, this option is not ideal. Radiographically, these curves should be mild (<15-20º) with a reasonable global sagittal balance and no lumbar kyphosis. The segments that need decompression should be stable as indicated by the presence of osteophytes or collapsed disc space and should not demonstrate subluxation (>2mm) on dynamic or standing radiographs. However, decompression may result in curve progression and worsening of symptoms, especially if done at the apex of the deformity.

2) Decompression with limited fusion within the deformity:

This option involves performing a limited fusion in the area of decompression. This is suitable for a patient with predominant leg pain (neurogenic claudication) who will require extensive decompression (e.g. severe lateral recess or foraminal stenosis, previous laminectomy, dynamic stenosis). The curve should be relatively small (<30º) without significant lumbar kyphosis or global imbalance. If there is an indication of segmental instability (vertebral subluxation >2mm, anterior, lateral or rotatory) without significant osteophytes or disc settling the segment should be fused.

Choosing fusion levels in limited fusion
The concern in limited fusion is accelerated degeneration of adjacent segment leading to spinal stenosis and progression of deformity. At the proximal end, it is advisable to include the adjacent segment that has a rotary subluxation or segmental kyphosis within the fusion [9]. Fusion from apex to sacrum have been shown to have poorer outcomes, hence if possible, fusion should not stop at the apex of the deformity [10]. At the proximal end, a decision must be made whether to extend fusion to sacrum. Frequently, the concavity of the fractional curve (L4 to S1) results in foraminal stenosis at L5-S1. Therefore, if the decompression involved L5-S1 segment the fusion should extend to the sacrum. Preexisting pathology (listhesis, pars defect) or severe disc degeneration are indications for extending fusion to the sacrum.
Hansraj et al in a large cohort of symptomatic spinal stenosis with degenerative scoliosis <20º, reported a 95% success rate (no revision surgery) of decompression alone surgery at four years follow-up [11]. Transfeldt et al compared three surgical groups: decompression only, limited fusion and full curve correction. Full curve correction group had the highest complication rate, the worst Oswestry results but it was second best in patient satisfaction. Decompression alone had the lowest complication rate but the lowest patient satisfaction rate. Limited fusion had intermediate results between these two groups [10]. Another retrospective study by Daubs et al found that in patients with curves <30º limited fusion groups outperformed the decompression only group for up to 5 years [12].

3) Fusion of entire deformity with or without decompression

This is indicated in patients with significant back pain with or without leg pain as a result of spinal deformity. Typically, these curves are large (>45º), with significant segmental subluxations (>2mm) or instability. The goal of curve correction is to restore global and regional imbalance. Literature indicates that proper restoration of the sagittal profile is critical for improvement of postoperative outcomes as measured by HRQOL scores [13].
The goals of surgery are to correct the deformity to achieve the following:
1) Lumbar lordosis should be corrected to within 10º of the pelvic incidence (PI-LL = ±10 degrees)
2) Sagittal vertical axis should be restored within 5 cm of the posterior superior corner of sacrum
3) Pelvic tilt should be restored to less than 25º
Surgimap software is an excellent graphical tool for preoperative planning to achieve these goals [14]. Depending on the flexibility of the deformity, various release procedures, ranging from facetectomy to three column osteotomy are employed to achieve these goals.

a) Proximal fusion level:
The most feared complication at the proximal end of the construct is PJK (proximal junctional kyphosis). Proper selection of proximal fusion level or the upper instrumented vertebra (UIV) may help reduce the risk of this complication

1) The UIV should be a stable vertebra. Preferable horizontal rather than tilted vertebra.
2) Evaluate the adjacent segment for spinal stenosis, olisthesis, facet arthropathy, and disc degeneration. One should consider including such level within the fusion.
3) Avoid stopping that the apex of focal or regional kyphosis. Physiological apex in the thoracic spine is around T6 and it is better to stop short (T10) or go beyond this level (T4 or above).
4) Avoid stopping in thoracolumbar region, if the thoracic spine has vertebral compression fractures or thoracic hyperkyphosis.
5) Shoulder balance needs to be considered. Unlike adolescent curves, the compensatory curves in adult deformity do not correct with reduction of the primary deformity. The compensatory curves may be stiffer due to degenerative changes and may require inclusion in the fusion to achieve should symmetry.
It is disputable whether to stop the fusion at T10 or L1/L2. Often the stable vertebra is going to be T12. It is a transitional area, and hence most authors recommend bypassing the area and going to T10, which is in a more stable region of the spine even if it means increasing the extent of surgery. Kuklo et al reported that only two of the 20 patients had good to excellent results when stopping at L1 or L2 [15]. However, Kim et al compared three groups with UIV of T9, T11, and L1 and found no difference in outcome at 4.5 years. [16] Cho et al concluded that there was no difference in adjacent segment problems between fusion to T10 and fusion to T11 or T12. They concluded that fusion to T11 or T12 was acceptable when UIV was above the upper end vertebra [17].

b) Distal fusion level
In degenerative scoliosis, the most common radiographic anomaly is L3-4 rotatory subluxation with a fixed tilt of L4-5. Hence, it is usually not possible to stop at L3 or L4 in degenerative scoliosis. Therefore, the options available for distal fusion level are L5, sacrum, or pelvis.

L5 or Sacrum?

This decision can be difficult and challenging. Advantages of stopping at L5 are preservation of lumbosacral motion, reduced stress on SI joints, lower operative time and lower nonunion rate [18]. However, stopping at L5 may be associated with adjacent segment disease and increase in sagittal imbalance as the L5-S1 disc collapses and goes into kyphosis. Edwards et al found adjacent segment disease in L5-S1 to be 61% out of which approximately 2/3rd had an increase in SVA by more than 5cm. Extension of fusion to sacrum was performed in 23% patients, and a further 17% were offered surgery, but they declined [19]. Contrary to the popular notion that deep seated L5 is relatively stable, this study found that loss of L5 fixation was not uncommon in such patients.
Obtaining fusion to sacrum can be a challenge and many have reported a significant nonunion rate [20,21]. In addition, it adds to the surgical burden and increases surgical time and blood loss. Bridwell [22] has recommend that fusion should extend to sacrum in the following situations:
1. L5-S1 spondylolisthesis
2. Central or foraminal stenosis at L5-S1
3. Oblique take off of L5 >15 degrees
4. Severe L5-S1 disc degeneration

L5 or pelvis?

Much of the ongoing debate has shifted from L5 versus S1 to a choice between L5 versus pelvis. Several studies have reported S1 screw failure and pseudarthrosis in patients with long fusion to the sacrum [23-25]. Iliac fixation, particularly with iliac screws, has gained popularity in the recent years. The downside of iliac screws could be their potential for loosening, implant prominence, and pain which may necessitate a hardware removal. However, this complication is not very common [18]. Some authors advocate an interbody fusion at L5-S1 (TLIF or ALIF) in addition to sacro-plevic fusion in patients with long constructs (>3 levels) to reduce failure rate due to pseudarthrosis [7].

Indications for extending fixation to pelvis are: [26]
1) Long construct: There is no clear definition of a long construct, but many surgeons recommend including the pelvis if the UIV is L2 or above.
2) Inability to achieve a good coronal or sagittal balance intraoperatively.
3) Poor sacral fixation (e.g. in osteoporosis)
4) High risk of pseudarthrosis (e.g. smokers, diabetics)
5) Inability to achieve a good interbody fusion at L5-S1
6) In patients undergoing three column osteotomies in the lower lumbar spine.

Minimally invasive techniques:
Minimally invasive, muscle sparing, tubular techniques are becoming popular to treat lumbar degenerative disorders. They have especially been useful in adult deformity patients to achieve decompression without damaging midline structures and help preserve the posterior tension band. They can also be used for limited fusion operations to reduce the surgical footprint and may reduce adjacent segment problems. However, in long constructs, it is still debatable whether minimally invasive techniques are as effective as open techniques in restoring sagittal and coronal balance [27].

Table 1

Case examples:

Case 1: (Fig. 3 and 4) Decompression with limited fusion
A 62-year old woman presented with predominant leg side neurogenic claudicatory pain attributed to foraminal stenosis (L4-5 and L5-S1) in the concavity of the fractional curve. The patient had failed all conservative measures. Standing radiographs (Fig. 3a) demonstrate a left sided lumbar curve of 25º with a fractional curve from L4 to sacrum of 18º. Supine films (Fig. 3b) show that the lumbar curve corrects to 19º and the fractional curve reduces to 10º. This suggests that the foraminal stenosis at L4-5 and L5-S1 is dynamic in nature, and a simple decompression is not going to relieve her of her symptoms. The lumbar lordosis is 50º, and it is within 10 degrees of the pelvic incidence (56º) (Figure 3c). The pelvic tilt is 7º. The global sagittal and coronal balance is normal. There is rotatory subluxation between L3-4 and anterior subluxation of L4-5 that is more than 2mm (Figure 3a), which is an indication for fusion to extend to L3 even though she does not have spinal stenosis at L3-4. Fusion was extended to sacrum as L5-S1 level had symptomatic stenosis (Fig. 3a). A TLIF procedure was added at L5-S1 level to improve foraminal height as well as to improve fusion rate. Satisfactory tricortical purchase was obtained in the sacrum and hence iliac fixation was deferred.

Figure 3 and 4

Case 2: (Fig. 5 and 6) Focal decompression with full curve correction using a long construct
A 74-year man presented with significant neurogenic claudication in both legs and severe back pain that has been unresponsive to conservative measures. The patient did not have any focal neurological deficit. Standing radiographs revealed 52º left lumbar curve with a fractional curve of 17º (Fig. 5a). There was a severe coronal imbalance (+8cm). Lateral standing radiographs showed positive sagittal imbalance (SVA +7cm), lumbar lordosis of -17º, and pelvic incidence of 59º. There was some amount of compensatory pelvic retroversion as indicated by a high pelvic tilt (PT 29º) (Fig. 5b). The goal of surgery was to achieve neural decompression as well as to restore global and regional balance (ideal postoperative alignment should have PT of <25º, PI-LL= ±10º and SVA <5cm). Surgery involved laminectomy and decompression of neural structures from L3 to S1 and posterior instrumented fusion from T10 to Pelvis (Fig. 6a). The flexibility and supine films showed 30% correction and posterior Ponté osteotomies were performed to release the deformity. The stable vertebra was T11 on preoperative radiographs and hence fusion was extended to T10, which is relatively stable segment due to its connection to the rib cage. There was no hyperkyphosis and hence fusion was not extended to the upper thoracic spine. As the fusion construct was long, additional iliac fixation was added to protect the S1 screw and improve the chances of achieving a successful lumbosacral fusion. Postoperative standing radiographs show a good restoration of coronal and sagittal balance. The lumbar lordosis is restored to -49º. Pelvic incidence minus lumbar lordosis is 11 degrees and there is improvement in pelvic tilt to 22º. SVA improved from +7cm to +1cm (Fig. 6).

Figure 5 and 6


Conclusions

The treatment of adult spinal deformity, surgical decision making and selection of fusion levels remains a complex and controversial process. Surgery in this population is risky and fraught with complications. Over the last few decades, our knowledge regarding these deformities has taken a quantum leap. However, there is still a lot of ground to cover. Therapeutic guidelines and classification system will evolve as researchers continue to search for answers.


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How to Cite this Article: Chaudhary K, Unnikrishnan R Management strategies and selection of fusion levels in adult spinal deformities.. International Journal of Spine Apr – June 2016;2(1):25-30 .

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Factors Influencing Sagittal Malalignment and its Effect on Clinical Implications in Adult Spinal Deformity

Volume 1 | Issue 1 | Apr – June 2016 | Page 5-9|Bassel G Diebo[1], Jeffrey J Varghese BS[1], Frank J Schwab[1].


Authors :Bassel G Diebo[1], Jeffrey J Varghese BS[1], Frank J Schwab[1].

[1]Department Spine Service, Hospital for Special Surgery, New York, NY, United States

Address of Correspondence
Dr. Bassel G. Diebo
Spine Service, Hospital for Special Surgery, New York, NY, United States.
Email: dr.basseldiebo@gmail.com


Abstract

Respect for the sagittal plane has been broadly published and accessible for all surgeons. Yet, suboptimal outcomes and revision cases remain highly prevalent. In this article, the authors present a case of a pleasant lady who started with a simple lumbar decompression surgery for spinal stenosis that deteriorated and then failed revision surgery, ultimately presenting with a severely disabling flatback and a remarkable spinal deformity. Her case highlights the importance of sagittal alignment in degenerative patients. Failure to appreciate the sagittal plane has a direct impact on patient reported outcomes and serious debilitating iatrogenic deformity. The maintenance of spinal alignment is not a deformity specific exercise; therefore, all surgeons should consider optimizing the sagittal plane to reduce the incidence of not only iatrogenic deformity but the burden of any spinal pathology.
Keywords: Sagittal Malalignment, adult spinal deformity, degenerative scoliosis.


Introduction
The close relationship between sagittal spinal alignment and patient reported outcomes is widely recognized [1–8]. As a result, sagittal radiographic parameters, such as the SRS-Schwab modifiers (Sagittal vertical axis: SVA, pelvic incidence minus lumber lordosis: PI-LL, and pelvic tilt: PT), have been investigated and validated in multiple spinal pathologies and patient groups. However, to date, iatrogenic causes remain an important contributor to the prevalence of adult spinal deformity. One reason for the increased incidence of iatrogenic deformity relates to the lack of correction and/or preservation of sagittal alignment when addressing focal or regional degenerative conditions. In addition to decompression and stabilization, maintenance of lumbar lordosis is crucial in avoiding the creation of deformities such as flatback syndrome [9]. The importance of the sagittal plane was originally established based on multi-center databases of spinal deformity patients; however, recent studies on patients undergoing less invasive procedures for lumbar degenerative conditions unraveled the universality of this importance. In a literature review of the last two decades, Mehta et al concluded that the sagittal parameters play a central role in the treatment of isthmic spondylolysis, spondylolisthesis, and degenerative pathologies [10]. Masevnin and Kumar et al have both demonstrated that adjacent segment pathologies are more prevalent in patients who underwent surgical correction of degenerative conditions without correcting sagittal alignment [11,12]. Finally, hypo- and hyperlordosis have been reported as risk factors for disc height reduction and facet joints arthritis, respectively [13,14]. Respect for the sagittal plane has been broadly published and accessible for all surgeons. Yet, suboptimal outcomes and revision cases remain highly prevalent [15–19]. In this article, the authors present a case of a pleasant lady who started with a simple lumbar decompression surgery and a subsequent failed revision surgery. Following a short fusion of L3-L5, the patient presented herself to the spine clinic of the senior author with a disabling flatback, an inability to walk more than 1 block, and a remarkable adult spinal deformity.

Case presentation:
History of present illness and physical examination:
This is a 70-year old Caucasian female who recently presented to the senior author’s clinic with a long history of back pain and two previous surgeries. In 2011, she had lumbar laminectomies and decompressions (L3-L5) and in 2012 she ultimately underwent a L3 to L5 instrumented fusion. Her severe (8/10) pain returned in 2013, originating in her buttock region, and traveled inferiorly through the right leg to the foot. For two years, the patient was only able to walk one block before she had to pitch forward from significant back pain and need external support. She underwent several non-operative treatments including: epidural injections, physical therapy, acupuncture, massages, and multiple nerve blocks. She is on Tramadol three times a day and one Percocet 5/325 every night. The patient stood with both sagittal and coronal malalignments (Fig. 1), was unable to toe or heel walk, and had poor tandem gait. She demonstrated right distal extremity numbness and weaknesses of both the tibialis anterior and extensor hallucis longus, but was otherwise neurovascularly intact.

Figure 1: Pre-operative anterio-posterior and lateral radiographs

Figure 1: Pre-operative anterio-posterior and lateral radiographs

Radiographic imaging:
CT scan:T12-Sacrum axial imaging revealed a mild degenerative scoliosis of the upper lumbar spine with the apex between L2-L3. Cephalad to the L3-L5 fusion, the patient had facet arthroses, a disc bulge, and central canal stenoses at T12-L1 and L1-L2. At the fusion levels, the patient had multiple degenerative discs, facet arthroses, and neural foraminal narrowings. X-Ray analysis: The patient presented with a pelvic incidence of 57°, indicating a standard pelvic morphology from a spinal perspective. Sagittal alignment analysis revealed a severe adult spinal deformity classified by the SRS-Schwab: PI-LL mismatch of 34° (++), PT of 40° (++) and SVA of 86 mm (++). Thorough analysis of the lumbar spine demonstrated a caudal (L4-S1) lordosis of 24°, L3-L5 (fused segments) lordosis of 18° and, L1-L2 (unfused segments) kyphosis of 6° (Fig. 2). The thoracic spine did not exhibit any hypokyphotic compensation (TK = 45°). Coronal x-rays revealed a 22° coronal curve (L1-L3) and a 65 mm right coronal malalignment. The full radiographic analysis is reported in Fig. 3.

Figure 2: Pre-operative sagittal radiographic analysis

Figure 2: Pre-operative sagittal radiographic analysis

Figure 3: Pre-operative segmental analysis of lumbar lordosis

Figure 3: Pre-operative segmental analysis of lumbar lordosis

Surgical planning and technique:
After discussing the treatment options, benefits, and risks, with the patient for her severe sagittal plane deformity, the decision was made to extend the fusion to T3 with pelvic fixation. The surgical strategy included a L3 pedicle subtraction osteotomy (PSO) of 35° and a L5-S1 transpedicular lumbar interbody fusion (TLIF) for an expected 10° of lordotic correction. Using dedicated software (Surgimap, Nemaris Inc, New York, NY), the surgical plan was simulated to ensure proper post-operative alignment. Patient-specific custom rods were generated and forwarded to the manufacturer to be pre-bent, ensuring an accurate execution of the surgical plan. In the OR, the reconstruction required additional T3-L2 Smith-Peterson osteotomies to afford fusion and deformity correction. At the osteotomy site, a wide laminar foraminotomy from L2 to L4 was performed and two short rods were added between these levels (Four-Rod technique), offering adequate correction and closure. Fluoroscopy confirmed that the proper correction was achieved in both planes.
Post-operative follow-up:
The patient recovered without incident, and is not only satisfied but happy with her new posture. Radiographic analysis revealed an adequate lumbar lordosis, a PI-LL within 10 degrees, a global sagittal alignment (SVA) of 36 mm, and a pelvic tilt of 28°. These are classified as (0), (0) and (+) based on SRS-Schwab classification. The lumbar coronal curve was corrected to 8 degrees and the C7PL to 16 mm to the right. (Fig 4)

Figure 4: Post-operative anterio-posterior and lateral radiographs

Figure 4: Post-operative anterio-posterior and lateral radiographs

Discussion:
There is a growing body of evidence in the literature regarding the clinical implications of sagittal spinal alignment. Over the last decade, scientific conferences are increasingly dedicating significant amounts of time and effort to raising awareness and spreading the sagittal message. The teaching today is: optimize or preserve the sagittal alignment of the spine in all spectrums of operations, from ‘simple’ one-level fusions to complex multi-planar deformity surgeries. For the management of spinal pathologies, it is no longer acceptable to perform only neural decompressions for stenosis and only fusions for stabilizing the spine. The sagittal plane, specifically with respect to lumbar lordosis, should be optimally aligned, if not already. This recommendation is valid almost regardless of the spinal etiology. To guide spinal realignment in adult spinal deformity, the key sagittal modifiers (PT, PI-LL, and SVA), with their clinically relevant thresholds, are already cornerstones for surgical correction. These parameters are also being investigated in patients with degenerative disc diseases, spondylolisthesis (degenerative and isthmic), as well as spinal stenosis. Moving beyond deformity: sagittal alignment in degenerative diseases:
In degenerative spondylolisthesis (DS), it is now established that higher pelvic incidences result in higher sacral slopes and shear stresses at the lumbosacral junction, making it a predisposing factor for DS. Moreover, Jeon et al took this a step further to conclude that degenerative retrolisthesis exists in two types, both of which are driven by sagittal parameters; one primarily resulting from degeneration in patients with low pelvic incidences, and the other secondarily resulting from compensatory mechanisms in patients with anterolistheses and high pelvic incidences [20]. Ultimately, sagittal alignment influences two out of the three features included in the Labelle classification of spondylolisthesis [21]. With regards to surgical treatment, Feng et al showed that the restoration of pelvic tilt and lumbar lordosis played important roles in the surgical outcomes of DS [22]. In other degenerative diseases, Bae et al demonstrated that patients with an upper lumbar disc herniation have significantly different sagittal profiles than patients with a lower disc herniation. In their studies, pelvic incidence and lumbar lordosis were significantly factors in determining the level of disc herniation [23)]. Thus, treatment of these pathologies is increasingly considering the sagittal plane.

Sagittal alignment in spinal stenosis:
Patients with lumbar stenosis adopt a forward compensatory bending posture to relieve the symptoms of neural compression [25,26].This malalignment pattern may be confused with sagittal spinal deformity and a loss of lumbar lordosis. Thus, there has been a recent debate on whether a surgeon should address the stenosis by decompression+/-fusion alone or with spinal realignment as well. Recent data demonstrated that decompression alone does indeed improve the sagittal profile of spinal stenosis patients. Jeon et al investigated 40 lumbar stenosis patients and followed them up to two years. In their study, patients who underwent decompressions alone had improvements in SVA, from 39 mm at baseline to 23 mm at 2 year follow up [24]. Buckland et al, in unpublished data, showed that while anterior truncal malalignment was similar between deformity and degenerative patients, pelvic tilt appeared to be a unique compensatory mechanism of deformity patients. Recently, Fujii et al showed that decompressions can improve global alignment in stenotic patients when malalignment is induced by a compensatory reduction in lumbar lordosis [27]. However, they also noticed that without corrective surgery, stenosis patients with higher preoperative malalignments (PI-LL > 21.5 and SVA > 69 mm) had residual malalignments postoperatively. This malalignment has proven to negatively impact patients reported outcomes in another study by Hikata et al [28)] In general, there is rising consensus that lumbar stenosis patients with severe sagittal malalignment (SRS Schwab SVA ++) should be assessed for a concomitant sagittal deformity and ultimately be considered for corrective surgery.
While more research is needed to establish treatment guidelines for sagittal realignment of spinal stenosis patients, it is crucial to understand that the maintenance of sagittal alignment is a must. The patient in this article deteriorated from being a spinal stenosis patient undergoing a two-level fusion to a flatback patient requiring realignment with osteotomy. This iatrogenic deformity is challenging and is commonly seen in daily practice of deformity surgeons. Based on the PI-LL formula, our patient needed approximately 50° of L1-S1 lordosis, of which 65% (32°) should be in the extreme caudal lumbar segments [29)]. However, when looking at the L1-S1 lordosis of this patient, she only had 21°. More importantly, the previously fused caudal segments were constructed with only 18°, which is a clear loss of lordosis.

Sagittal alignment: How to improve, What is new and How to be more patient-specific?
To improve our understanding of the sagittal plane, the gap between researchers and clinicians must be bridged. Feedback from surgeons in daily practice is crucial to improve the current guidelines of sagittal realignment. The ultimate goal is a personalized treatment that addresses the patient’s age, pathology, function, expectations, and spino-pelvic morphology.
Lafage et al investigated the impact of age on the spino-pelvic alignment and provided updated thresholds of PT, PI-LL and SVA [30]. The new targets for the radiographic parameters provide more “patient-specific” alignment thresholds. Their data revealed that age should be considered when determining the ideal sagittal alignment for a given patient, with older patients requiring less rigorous alignment objectives (Table 1).

Table 1: Age-adjusted sagittal alignment thresholds.

Table 1: Age-adjusted sagittal alignment thresholds.

Moreover, patient-specific instrumentation is a recent advancement in spine surgery. Surgeons can now plan their surgery and choose or construct certain instrumentations based on their patient’s morphology and alignment targets. Using the existing knowledge on the optimal sagittal alignment, these customized implants might help preserve the sagittal plane in degenerative patients. There are several factors that need to be acknowledged to achieve or maintain adequate sagittal alignment of the spine. The pelvis is a key component that must be considered. The measurement of pelvic incidence (PI) and the calculation of the mismatch between PI and lumbar lordosis are crucial in assessing the deformity magnitude when its main driver is the loss of LL. Any mismatch > 10° is associated with worse patient reported outcomes. Every surgeon needs to ensure that the surgical intervention does not alter this harmony between the spine and the pelvis [1,4]. Moreover, analysis of the compensatory mechanisms recruited by each patient is mandatory. Pelvic tilt, thoracic hypokyphosis, and knee flexion [31] are common mechanisms that need to be considered and delineated from the main driver of deformity. The surgery needs to be planned with the help of dedicated software and the plan needs to be simulated to confirm that post-operative alignment is ideal [32,33]. Finally, patient expectations, comorbidities, and their soft tissue profile are highly important aspects to consider. These are being investigated for their impact on how we treat our spinal pathology patients.


Conclusions

This article, drawing support from cases and the plethora of literature available, highlights the importance of sagittal alignment in degenerative patients. Failure to appreciate the sagittal plane has a direct impact on patient reported outcomes and serious debilitating iatrogenic deformity. The maintenance of spinal alignment is not a deformity specific exercise; therefore, all surgeons should consider optimizing the sagittal plane to reduce the incidence of not only iatrogenic deformity but the burden of any spinal pathology.


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How to Cite this Article:Diebo BG, Varghese JJ, Schwab FJ. Factors Influencing Sagittal Malalignment and its effect on Clinical Implications in Adult Spinal Deformity. International Journal of Spine Apr – June 2016;1(1):5-9.

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