BackgroundA feasibility trial was conducted to evaluate the initial safety and clinical use of a next-generation artificial cervical disc (M6-C artificial cervical disc; Spinal Kinetics, Sunnyvale, CA) for the treatment of patients with symptomatic degenerative cervical radiculopathy. A standardized battery of validated outcome measures was utilized to assess condition-specific functional impairment, pain severity, and quality of life.MethodsThirty-six consecutive patients were implanted with the M6-C disc and complete clinical and radiographic outcomes for 25 patients (mean age, 44.5 ± 10.1 years) with radiographically-confirmed cervical disc disease and symptomatic radiculopathy unresponsive to conservative medical management are included in this report. All patients had disc-osteophyte complex causing neural compression and were treated with discectomy and artificial cervical disc replacement at either single level (n = 12) or 2-levels (n = 13). Functional impairment was evaluated using the Neck Disability Index (NDI). Evaluation of arm and neck pain severity utilized a standard 11-point numeric scale, and health-related quality of life was evaluated with the SF-36 Health Survey. Quantitative radiographic assessments of intervertebral motion were performed using specialized motion analysis software, QMA (Quantitative Motion Analysis; Medical Metrics, Houston, TX). All outcome measures were evaluated pre-treatment and at 6 weeks, 3, 6, 12, and 24 months.ResultsThe mean NDI score improved from 51.6 ± 11.3% pre-treatment to 27.9 ± 16.9% at 24 months, representing an approximate 46% improvement (P <.0001). The mean arm pain score improved from 6.9 ± 2.5 pre-treatment to 3.9 ± 3.1 at 24 months (43%, P =.0006). The mean neck pain score improved from 7.8 ± 2.0 pre-treatment to 3.8 ± 3.0 at 24 months (51%, P <.0001). The mean PCS score of the SF-36 improved from 34.8 ± 7.8 pre-treatment to 43.8 ± 9.3 by 24 months (26%, P =.0006). Subgroup analyses found that patients treated at single level and those with a shorter duration of symptoms showed better functional results. By 24 months, the mean range of motion (ROM) value at the treated level had returned to approximately pretreatment levels (12.2° vs 11.1°). There were no serious device-related adverse events, surgical re-interventions or radiographic evidence of heterotopic ossification, device migration, or expulsion in this study group.ConclusionsThese findings indicate substantial clinical improvement for all function, pain, and quality of life outcomes in addition to maintenance of ROM and increase in disc height at the treated level(s). The findings also exhibit an acceptable safety profile, as indicated by the absence of serious adverse events and reoperations following arthroplasty with a next-generation artificial cervical disc replacement device.

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IntroductionIn surgical treatment of vertebral fractures, the most important aspects are the instrumentation system, which has to prevent movement along the three axes of the spine, and placing two surfaces of healthy bone together, or better yet, placing a very good construct with surgical coaptation of two plain surfaces [1,2,4,5,7,9,10,12].Burst fractures may be stable or unstable [11]; that is why controversy exists as to the best approach (anterior or posterior) and stabilization system to use [8,12].We know the following about burst fracture treatment 1. With a posterior approach, good results are achieved in only 60-70% of patients [2,3,5,6,12]. 2. An anterior approach is necessary in 20-30% of patients, as a complementary approach or as a primary indication [5,7,12]. 3. Fixation offers early physical therapy without the use of a brace [1,3,4,11,12]. 4. Careful arthrodesis with autologous bone graft is the most desirable procedure [8,12].Abstract Burst fractures may be stable or unstable, so the choice of treatment may be controversial; almost all cases are surgical type. Deciding on the best method and approach is difficult, due to the many possible options and the fact that good results are achieved in only 60-70% of cases. The main problems to be resolved are the residual kyphosis or the recurrence due to loss of reduction. This is a prospective, observational, longitudinal and descriptive study of six patientstwo men and four women, mean age 46 years -who scored 7 or more points according to the load distribution classification, and were treated with vertebral shortening by a posterior approach and transpedicular fixation with INO plates. Follow-up was for a period of 2 years, and included evaluating pre-and postoperative stability and kyphosis among other data. The results showed a reduction in the mean fracture angle from 17°preoperatively to 1°post-operatively. Full stability was achieved in five patients, and incomplete stability in one patient, who recovered with the use of a corset.There was evidence of arthrodesis in all six patients within 9 months. The use of an anterior approach to treat burst fractures is well recognized; however, treatment with vertebral shortening using a posterior approach has the advantages of less bleeding, shorter surgical time and less residual kyphosis, as a result of putting together two flat surfaces of healthy bone. The residual kyphosis in the present series, after the 2-year follow up, was less than 1°, which is lower than the 5°-10°reported in the literature.