Thoracic spine fractures: injury profile and outcomes of a surgically treated cohort (2024)

Abstract

There are only few reports in literature about the treatment of traumatic lesions of the thoracic spine. They have been grouped together with thoracolumbar fractures, ignoring the particular biomechanics of the thoracic segment. The objective of this retrospective cohort is to describe the clinical presentation and outcomes of surgically treated patients with these injuries. Data were obtained from the institutional database of medical registries, identifying all the patients who had been treated for thoracic spine fractures, from January 1, 1995 through December 31, 2005 in our institution. The study group included the 51 surgically treated patients. General and surgery-related complications were considered as clinical outcomes and injury-related disability was also assessed. Statistical analysis evaluating possible associations with timing and type of surgery, neurological impairment and associated injuries was carried out. Motor vehicle accident was the most frequent mechanism of injury. Six patients had an incomplete neurological deficit, whereas 22 had a complete lesion. Thirty-two patients presented at least one complication. Five of the neurologically intact patients, while 20 of those with neurological impairment presented general complications (p=0.0001). None of the patients’ neurological status deteriorated after surgery. All patients with complete spinal cord injury and those with incomplete cord injury with partial functional recovery received disability compensation. Short pedicle instrumentations should be used whenever possible, but also long instrumentations and mixed constructs may be necessary for the management of such unique fractures.

Keywords: Thoracic spine fractures, Spinal instrumentation, Thoracic trauma

Introduction

The thoracic spine has unique anatomical and biomechanical features. It is much stiffer than the lumbar spine due to the restraining effect of both the rib cage and its relatively thinner disks [1]. The radiate and costotransverse ligaments bind the ribs to their respective vertebrae, contributing with this region’s rigidity [2].

Another important difference between the thoracic and the lumbar spine is the presence of the spinal cord in the former. In this region, a narrower spinal canal implies less free space available between the cord and the osseous ring. This fact, together with the relatively sparse blood supply of the central thoracic spine could explain the occurrence of spinal cord injury with less compression or kyphotic deformity than in the lumbar spine [3].

Therefore, thoracic spine fractures differ in their clinical presentation compared to fractures at other levels and should be managed with distinct criteria.

There are only few reports in the literature regarding the treatment of traumatic injuries of the thoracic spine. They are usually grouped together with thoracolumbar fractures ignoring its distinctive biomechanical characteristics and its differences with the thoracolumbar junction and the lumbar spine [4].

In addition, there is no consensus regarding instrumentation type, construct, fusion length nor the need for anterior decompression of the spinal canal [5]. In this report, we describe the clinical presentation and outcomes of surgically treated patients with thoracic spine fractures (T2–T10). Based on our results, a treatment suggestion for these injuries is also proposed.

Patients and methods

We conducted a retrospective institutional database review of medical registries. All patients treated for thoracic spine fractures, from January 1, 1995 through December 31, 2005 in the Hospital del Trabajador de Santiago were identified. A total of 123 patients with traumatic non-pathological thoracic spine fractures were found. Fifty-three (43.1%) had surgical indications. One patient died secondary to hepatic and vascular (vena cava) injury before spine surgery and another patient refused surgery. The remaining 51 patients were included in our study cohort.

Information extracted from each patient’s medical record included demographics, injury mechanism, latency to surgery, fracture type, level, neurological impairment, associated injuries, type of surgical procedure and associated complications. Data were analyzed using a non-parametric test (χ²—Fischer’s exact test; according to distribution) to evaluate relationships between the studied categorical variables.

All fractures were classified according to AO/ASIF classification [6] using plain radiographs, complemented with a computerized tomography (CT) and magnetic resonance images (MRI). Patient’s assessment included the ASIA (American Spinal Injury Association) Impairment Scale [7] for neurological function.

Results

The study group included 51 patients with a surgically treated thoracic spine fracture. Table1 shows demographic information of the study sample, including injury mechanism, neurological impairment and any additional vertebral fractures.

There were 44 male (86.3%) and 7 female (13.7%) patients, with a mean age of 38years (19–72years). Motor vehicle accident was the most frequent injury mechanism (48%), followed by fall from a height (43.1%). The remaining four patients (7.9%) were injured by other mechanisms (direct trauma in three patients and gunshot in one patient).

Table2 shows fracture type distribution, according to the AO/ASIF classification.

Spinal cord injury (Fig.1): 23 patients (45.1%) were intact (ASIA E), 6 patients (11.8%) had an incomplete neurological injury (ASIA B–D) and 22 patients (43.1%) had a complete lesion (ASIA A). All patients with neurological impairment were treated according to the NASCIS II protocol [9].

Based on the recent evidence [10], we considered 24h after the accident as the time limit to differentiate early from delayed surgery.

Discussion

We describe the results of the surgical treatment of a cohort of patients with thoracic spine fractures. The available literature describes these fractures as severe injuries, with an important incidence of associated lesions, caused by a high energy trauma [17]. In our study group, 70.6% of the patients had associated injuries, including thoracic and abdominal viscera, thoracic cage, limbs and other spinal segments and systems. Forty-five percent of the patients had two or more of these associated injuries, confirming the fact that thoracic spine fractures may be related to life-threatening conditions [18]. This way, a thoracic spine fracture must be suspected in any patient with multiple injuries after a high-energy trauma. Given the anatomically congested area that surrounds the thoracic spine, fractures in this segment may be difficult to identified using only plain X-rays. To avoid under diagnosis, a CT scan should be obtained [19, 20]. In addition, complementary MRI allows an accurate evaluation of the soft tissues (inter-vertebral discs, ligaments and spinal cord) [21].

A higher incidence of neurological impairment has been associated with thoracic spine fractures, due to the decreased cross-sectional area of the spinal canal (thoracic canal to spinal cord ratio close to 1) compared with other spinal segments [22]. In our cohort, 54.9% of the patients presented some degree of spinal cord injury. We reported no cases of neurological recovery in patients with complete deficit, while the majority (83.3%) of those with an incomplete injury recovered at least one degree in the ASIA scale. In our analysis, neurological impairment was statistically associated with a higher complication rate after spine surgery. In a systematic review, Verlaan et al. [23] also described this finding in surgically managed thoracic and lumbar spine fractures.

When planning the surgical treatment of these fractures one must consider the particular anatomy of the thoracic spine, specifically the physiological kyphosis and the smaller pedicle size of the middle thoracic vertebrae.

The lever arm needed for reduction usually implies the inclusion of a greater number of healthy segments in the fixation. This issue may be irrelevant in the thoracic spine, due to its intrinsic and extrinsic rigidity: relatively shorter disk height (20% of vertebral body height vs. 40% in the lumbar spine), trapezoidal vertebral body, facet joint orientation [24] and the restraining effect of the thoracic cage [25–27]. Particularly, we observed that sternum fracture adds instability to this type of injuries.

Twenty-two patients (49%) in this cohort required instrumentations of five or more segments. On the other hand, hooks configuring claws were used in 13 patients (25.5%), due to a smaller pedicle width (<4mm) in the cephalic levels (Fig.2).

There is no level I evidence to support a specific construct or instrumentation for the management of these fractures. When considering that our incidence of surgery-related complications is the lowest one reported in the literature, with the largest group of patients [23, 28] and with no significant differences between short and long instrumentations (including mixed ones with pedicle screws and hooks), we recommend the use of short instrumentations with pedicle screws whenever possible. Hooks configuring claws should be considered as an alternative when the pedicle diameter is <4mm. Longer instrumentations may be used to facilitate and improve reduction.

No patient in our study group presented neurological deterioration due to the surgical procedure or fixation technique. We report no cases of pseudoarthrosis during our follow-up and only one fixation collapse. This patient achieved consolidation, after a deep infection was treated with antibiotics together with surgical debridement and irrigation.

Neurological impairment was the only element related with disability. An inferior performance was reported among the patients that returned to great physical activity jobs after the accident. No other relationships with functional outcomes could be established when analyzing other factors, such as age, time to surgery and instrumentation length.

Conclusion

Thoracic spine fractures that require surgical treatment occur more frequently in polytrauma patients and are often associated with neurological impairment and such patients may have associated life-threatening injuries and should be addressed via a multidisciplinary team approach. Neurological impairment was found to be the most important predictor of complications and disability in our study group. In addition, the restoration of physiologic kyphosis and fracture reduction may require larger lever arms. We recommend the use of short pedicle instrumentations whenever possible, considering long instrumentations, together with mixed constructs, when necessary, for the management of such unique fractures.

Acknowledgments

The authors did not receive grants or outside founding support of their research or for preparation of this article.

References