| Ossification of the posterior longitudinal ligament (OPLL) is a kind of degenerative diseases that may leads to myelopathy. There has been nearly 50 years since it was first reported in the year 1960 when Tsukimoto found this kind of lesion during the autopsy and demominated as OPLL in 1964 by Terayama. With the research going on, OPLL have been found in cervical thoracic and also lumbar segments in succession. Thoracic myelopathy caused by OPLL is rare compared to cervical OPLL. However, once myelopathy appears in patients with thoracic OPLL, it is progressive and often leads to serious paraplegia.Diagnosis of OPLL may not be difficult with the help of careful physical examination and radiographs which contain plain radiography, computed tomography (CT) and magnetic resonance imaging (MRI). Computed tomography (CT) is sensitive and is thus indispensable for visualizing the detailed outline of an ossified mass. OPLL is observed as a high-density ossifying mass lying dorsal to the vertebral bodies or discs on CT scans. Reconstruction CT is particularly helpful for determining the thickness, coronal and sagittal extension, the shape of the OPLL, and the extent of narrowing of the spinal canal by OPLL. MRI is less sensitive and less specific for the diagnosis of an ossified mass, its principal use is in the assessment of associated cord compression and intramedullary cord lesions such as cord edema and myelomalacia.With the rapid development of the radiography, it may be easier to diagnosis this kind of disease. But satisfying outcomes are not always achieved. When myelopathy appears, surgical treatment is required because the mechanical stability of thoracic spine is greater than that of the cervical spine and conservative treatment is not effective. When myelopathy is mild, both surgeons and patients sometimes hesitate to undertake surgery because of the potential risk of the severe complications that might occur after operation. As myelopathy progresses, the risk of surgery increases, which presents a dilemma for both patients and surgeons.The choice of surgical treatment can be divided into two categories based on the type of decompression. The first is direct removal of the thoracic OPLL, while the second is indirect posterior decompression of the spinal cord without directly touching the OPLL. Several methods of surgical treatment have been advocated, including anterior decompression via anterior approach (including transsternal and transthoracic approach), indirect decompression via the posterior approach, circumspinal decompression and anterior decompression via posterior approach (Ohtsuka Procedure). Though the use of intraoperative C-arm X-ray unit, image-guided technology, spinal cord monitoring and ultrasonic inspection had enhanced the security of the surgical treatment to some extent, the choice of surgical decompression is still controversial because neurological deterioration and other complications may occur with any technique. Our study focus on the 4 patients who underwent surgical treatment for OPLL via transthoracic approach in our department. The radiography information, surgical treatment and other characteristics are recorded, then we take retrospective study to evaluate the outcomes of this method and try to amass valuable information for the subsequent treatment.Objective: To evaluate the outcomes of surgical treatment via transthoracic approach for OPLL patients and try to amass valuable information and provide reference for the following treatment.Meterials and Methods:A total of 4 patients (2 men and 2 women, mean age 45.25) with OPLL of the thoracic spine who underwent surgical treatment with anterior decompression via transthoracic approach in orthopedics department of Third Hospital of Jilin University between 2008.10 and 2009.08 were enrolled in the retrospective study, with a mean follow-up period of 12 months. The items investigated were the patients'general conditions, presence/absence of comorbidity, the length of morbidity period, radiologic findings [x-ray, computed tomography (CT) and magnetic resonance imaging (MRI)], surgical methods, complications, and the surgical outcomes.Before operation, the typical symptom of spastic gait occurred in all the 4 patients, symmetrical numbness in lower extremity and trunk in 3 cases, asymmetrical numbness in 1 case, weakness of the muscles in lower limbs in 2 cases, obvious changes of bladder function. In 2 cases and severe constraint of the trunk in 1 case. Once symptoms mentioned above appeared, it was progressive and turned up in succession.The OPLL lesion of all the 4 patients demonstrated a multi-segment distribution and had the combination of OLF.All the 4 patient received direct decompression of ossified segment via transthoracic approach, removal of all ossification in 3 cases, floating for 1 case with severe adhesion. Instrumentation and fusion with titanium mesh cage were used after decompression for all these cases.The surgical outcomes were assessed by the JapaneseOrthopedic Assoc- iation (JOA) score for thoracicmyelopathy (total of 11 points), which was derived from the JOA scoring system for cervical myelopathy by eliminating the motor and sensory scores for the upper extremity. The recovery rate was calculated using Hirabayashi's formula; Recovery rate=(JOA score at follow-up- preoperative JOA score)/(11-preoperative JOA score)×100%. The recovery rate of more than 50% is considered the satisfying outcome of the treatment.Results:The postoperative symptoms of numbness and bladder dysfunction had gained obvious recovery. Motor function had promoted in 3 of the 4 patients, except 1 with immediate neurological deterioration after the surgery. The postoperative radiographs confirmed the effect of decompression and instrum- entation. The average preoperation JOAs was 3 (ranged 1-5), and it went up to 7.75 (ranged 6-9) and gained a mean recovery rate of 58.13% at the latest follow-up. The recovery rate is more than 50% in 3 patients.Two patients suffered from severe complications. The first patient underwent a deterioration of thoracic myelopathy immediately after the surgery and the JOA scores went down to 0. Though the sensory and bladder function had started to recover since the second week afer the surgery. The recovery of the motor function is not satisfactory till now. The second one suffered from the complication of cerebrospinal ?uid leakage because of the severe adhesion between dura mater and OPLL. The patient experienced long time of headache and the healing of incision had been hampered.Conclusions:OPLL of the thoracic spine has a low clinical incidence, and the symptoms of myelopathy tend to be progressive. The diagnosis of OPLL rely on careful physical examination and auxiliary examination of computed tomography (CT) and magnetic resonance imaging (MRI). OPLL of the thoracic spine are frequently combined with OLF and demonstrate as a multi-segment distribution. Anterior decompression via the transthoracic approach is regarded as an effective method, especially for the beak type and the OPLL in the milddle and lower segments. In some cases, floating of the ligament or selective extirpation for a certain segment is also helpful. For those patients with a long morbidity period, the incidence of severe complications is likely to increase, such as cerebrospinal ?uid leakage and immediate neurological deterioration after the surgery. Therefore, early diagnosis and surgical intervention is essential for pursuing good outcomes of treatment.
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