TOTAL CERVICAL DISK REPLACEMENT WITH A PRESTIGE LP ® PROSTHESIS : CLINICAL AND FUNCTIONAL OUTCOMES ARTROPLASTIA TOTAL DO DISCO CERVICAL

Study conducted at the Centro da Coluna Vertebral (CECOL), Rio de Janeiro, RJ, Brazil. Correspondence: Rua Souza Lima, 257, ap. 501, Copacabana, Rio de Janeiro, RJ, Brazil. rafaelosoriorocha@hotmail.com AbstrAct Objective: To determine the clinical and functional results of shortand medium-term cervical arthroplasty with the Prestige LP® prosthesis for the treatment of compressive myelopathy, radiculopathy and axial pain with radiculopathty. Methods: This retrospective study, conducted from 2009 to 2012, included 18 patients. Only 16 were found for the second stage of research, conducted in 2011 and 2012. Preand postoperative assessments were carried out using the CSOQ (Cervical Spine Outcomes Questionnaire). Odom criteria were used only in the postoperative evaluation. Both were translated and adapted to the local culture. Results: There was no postoperative radiculopathy or other complications requiring prolonged hospitalization. In most patients, there was a significant improvement in axial pain and radiculopathy, and there was only one indication of conversion to fusion. Conclusions: In selected cases of cervical degenerative disc disease, herniated cervical disc and compressive myeolopathy, cervical arthroplasty proved to be an effective and safe treatment in the short and medium terms.

Seeking to preserve the physiological kinematics of the cervical spine, replacement is an option for the treatment of cervical disc di-seases, and safe insertion and clinical success have been reported in several studies. 13,14 This study describes our experience with cervical replacement using the Prestige LP ® prosthesis (Medtronic Sofamer Danek, USA), a prosthesis with two ceramic and titanium components, and evaluates the improvement to the quality of life and the level of patient satisfaction.

MAtErIALs AND MEtHODs
A retrospective study was conducted, which included 18 patients in the period from 2009 to 2012. Two patients could not be located for participation in the second phase of the study. All had undergone anterior approach cervical replacement with a Prestige LP ® prosthesis. Inclusion criteria 15 : Symptomatic patients with radiculopathy or myelopathy; degeneration of one or two levels between C3 and C7; no prior cervical surgery; and with cervical mobility.
Exclusion criteria 15 : Active infection; osteoporosis; tumors; radiological evidence of mechanical instability or lack of mobility at the treatment level confirmed in preoperative dynamic flexion-extension radiographies; cervical facet joint arthritis; solitary axial pain; and those patients who could not be located for the second phase of the interview.

Surgical technique
An anterior Smith-Robinson approach to the left of the cervical spine was performed. The median line and the level were identified and marked, and vertebral distraction pins were placed to perform the discectomy, resection of the posterior longitudinal ligament, and bilateral neuroforaminal decompression.
The endplates were prepared so that they were parallel, taking care to preserve as much cortical bone as possible. A rasp was used to assist in the preparation of the endplate to improve the fit of the implant. The template was positioned in the disc space and the size of the prosthesis was verified, taking care not to distract the articulations or the disc space. The rail cutter guide was used to form the four parallel fixation channels in the endplates. The rails of the Prestige LP ® prosthesis were aligned with the endplate channels for the insertion of the prosthesis.
Intraoperative anterior posterior and lateral fluoroscopes were performed to verify the correct placement.
For the evaluation, we used the CSOQ (Cervical Spine Outcomes Questionnaire) 16,17 because it is more specific for the evaluation of both pre-and postoperative pain and functionality related to cervical diseases. Odom's Criteria 18 were used only postoperatively.
The age range of the 16 patients varied from 27 to 50 years. There were eight male and eight female patients.
Odom's Criteria were applied as follows: Odom's Criteria Excellent: Improvement of most (at least 80%) of the preoperative signs and symptoms, with little deterioration (not more than 10%). No complaints related to cervical disc disease. Daily tasks are performed without limitations; Good: Improvement of some (at least 70%) of the preoperative signs and symptoms, with some deterioration (not more than 15%). Intermittent discomfort related to cervical disc disease. Daily tasks are performed without significant limitations; Fair: Improvement of at least 50% of the preoperative signs and symptoms, with some deterioration (not more than 20%). Subjective improvement, but physical activities are significantly limited; Poor: Improvement of a few (less than 50%) of the preoperative signs and symptoms, or significant deterioration (more than 20%). No changes or worse as compared to the situation prior to the operation.
Used constantly in scientific articles, Odom's Criteria are highly specific for the assessment of cervical pathologies as regards pain and the performance of daily activities. The CSOQ was selected to analyze other parameters (physical symptoms, psychology evaluation, and the need for medication, among others).
The CSOQ is a specific tool for the assessment of cervical pain and the results of treatment, providing information about the severity of the pain, functional measurements, psychological distress, physical symptoms, and the measurement of health care. It is easy to understand and highly reliable. (Attachment 1)

CSOQ assessment
Each score was converted into a number from 0-100. Higher numbers indicate greater bodily dysfunction in addition to: I -gre-ater severity of cervical pain; II -severity of shoulder and arm pain; III -greater functional limitation; IV -tendency towards more stress, depression; V -higher frequency of physical symptoms other than pain; VI -high frequency of the use of health care mechanisms.

rEsULts
According to Odom's Criteria, 62% of the patients had excellent results, 13% good results, 19% fair results, and 6% poor results. (Figure 1) In most cases, there was no postoperative radiculopathy or any other complication requiring extended hospitalization. There was a significant improvement in axial and radicular pain, enabling a return to work, personal and leisure activities, and even sports. Sexual function was only slightly impacted by the disease, and improved following surgery.
In one of our cases, there was a failure in the fixation of the prosthesis with anterior migration. Conversion to an ACA was indicated.
The results of the CSOQ (Cervical Spine Outcomes Questionnaire) scores are shown in Figures 2 to 10.

DIscUssION
Cervical replacement promotes the preservation of kinematics closest to the physiological standard [19][20][21] and is a possible long-term solution for the problem of adjacent discopathy encountered in patients who have undergone arthrodesis. 5 In our study, we had a very short period of time to evaluate the incidence of adjacent discopathy.
There are several types of prostheses, classified by number of components, material, and biomechanical design. 22 The Prestige LP ® prosthesis has two-hinged titanium and ceramic components and a ball-in-trough biomechanical design that allows anterior posterior translation coupled with flexion/extension movement in a combination that is very close to normal. 23 Fixation of the Prestige LP ® prosthesis in the vertebral body is achieved through tracks that allow a smaller anterior prominence in the profile of the prosthesis, in addition to reducing fractures of the vertebra, common in the insertion of prostheses with keels. 23 According to Swiss Spine 24 , the aspects that most influence patient recovery are the intensity of preoperative pain, the quality of life prior to surgery, and the preoperative use of psychotropic medications. The greater the intensity of the preoperative pain, the greater the improvement of symptoms. Patients with a highly compromised quality of life tend to have better outcomes. The prior use of psychotropic drugs was associated with unsatisfactory results.
Given the amount of the time and experience with knee and hip replacements, other complications, like breakage of implants due to fatigue, loosening of the bone-implant interface, sinking of the endplate, and infection can be observed. These complications were not observed in the short or medium term. However, this can only be confirmed over time, with the long-term monitoring of these patients.
Further studies will be necessary to confirm the promising results of cervical replacement.

cONcLUsION
We observed similarities between the results obtained in this study and in several current studies, and conclude that total cervical replacement is a safe and effective method for short-and mediumterm treatment when indicated in cases of degenerative discopathy, disc herniation, and myelopathy.
All authors declare no potential conflict of interest concerning this article.