Purpose of the study: The development of a cervical kyphotic deformity can be associated with a degenerative disease, trauma, tumour, developmental anomaly and also a surgical procedure. Post-operative kyphosis can develop after both the anterior and posterior surgical approaches. The deformity can also result from systemic diseases, such as ankylosing spondylitis or rheumatoid arthritis. The aim of the study was to make the clinical and radiographic evaluation of a group of patients with kyphotic deformity treated at our department.
Material: Between May 2005 and April 2010, a total of 102 patients underwent correction of cervical kyphosis at our department. (Center for Spinal Surgery). Of them, 90 patients with complete medical records and post-operative periods longer than 6 months were included in this study. There were 36 men and 54 women ranging in age from 13 to 90 years and with an average of 56.7 years. In six patients cervical kyphosis was caused by an inveterate injury, in 71 by degenerative disease, in six it developed in association with rheumatoid arthritis, and in seven patients it was due to previous surgery. Patients with acute trauma, tumour, infectious disease or congenital anomaly were not included.
Methods: All patients were examined before surgery by radiography in antero-posterior and lateral projection, including flexion- extension bending films, and by CT scanning of ultrathin cross-sections with sagittal, frontal and recently also 3D reconstructions. Magnetic resonance imaging in three planes was also performed. On the basis of the results and clinical examination, the operative strategy was planned. Surgery was carried out from the anterior or the posterior approach, or the combined approach was used. Three-stage surgery was performed in one patient. The surgical outcome was assessed using the Nurick score and Neck Disability Index (NDI), the Visual Analogue Scale (VAS) was used to evaluate pain intensity or paraesthesia. Statistical analysis was done using the Chi-square test and paired t-test.
Results: The average NDI value was 25.5 before surgery and 14.3 and 14.9 at one and two years after surgery, respectively. Compared with the pre-operative state, improvement or no changes were recorded in 89.7 % of the patients; transient deterioration occurred in 10.3 %. Improvements found were as follows: by one degree in 46.2 % of the patients, by two degrees in 18 %, by three degrees in 5.1 % and by five degrees in 2.6 % of the patients. The condition remained unchanged in 18 % of the patients. The average outcome was an improvement by one degree. The average pre-operative Nurick score was 0.7; an average post-operative value of 0.6 was recorded at both one and two years of follow-up. The average VAS value for neck and radicular pain was 5.7 pre-operatively, and 2.5 and 2.7 at one and two post-operative years, respectively. Out of 90 patients, complete bone union was achieved at 6 months after surgery in 88 patients (97.8 %). The average pre-operative value for the cervical curvature index (Ishihara) was -13.7; the average pre-operative cervical kyphosis was -14.4 degrees, ranging from -2.2 to -44.0 degrees. After surgery, the average Ishihara index was +15.3 and the average lordosis was +13.5 degrees, with a range of -16.0 to + 37.4 degrees.
Discussion: A single/isolated anterior approach can be used for fixed deformities without ankylosing spondylitis. It allows for decompression of the anterior pathology and for correction of cervical kyphosis with use of instrumentation and structural graft. A combined ventral-dorsal approach is appropriate in fixed deformities or deformities involving the cervico-thoracic junction. The main principle of correction is to lengthen the cervical spinal column in the front and to shorten it at the back by anterior decompression with or without instrumentation and by subsequent posterior stabilisation. An isolated/single dorsal correction can be used in the case of successful correction by traction or specific head positioning on the table without anterior nerve compression. In severe fixed deformities such as Bekhterev's disease, the chin can be so close to the chest as to interfere with eating and breathing. The deformity most often develops at the cervico-thoracic junction and requires treatment by osteotomy.
Conclusions: The results of the study showed a marked improvement in the patients' quality of life after kyphosis correction, improved neurological status and an improved posture seen on radiograms of the cervical spine. The study also revealed a higher number of potential complications associated, in particular, with corrective osteotomy. The best results were achieved with the combined surgical approach; however, the choice of a surgical method was independent of the patient's clinical status.