Clinical experience with the new artificial cervical PCM (Cervitech) disc

doi:10.1016/j.spinee.2004.07.024

The Spine Journal

Volume 4, Issue 6, Supplement, November–December 2004, Pages S315-S321

https://doi.org/10.1016/j.spinee.2004.07.024 Get rights and content

Abstract

The results of a pilot study performed between December 2002 and October 2003 in which 82 cervical disc arthroplasties were implanted in 53 patients are reviewed in detail. Visual Analog Scale (VAS) pain scale, Neck Disability Index (NDI), and Treatment Intensity Gradient Test (TIGT) scales were evaluated as were static and dynamic radiographs. Significant improvents in all scales were seen postoperatively. One device migration of 4 millimeters was seen at 3 months and observed. Eighty percent of patients had a good or excellent result at one week, improving to ninety percent of patients being judged to have a good or excellent result by one month (Odom's criteria), which then remained at ninety percent at 3 months.

Introduction

The Porous Coated Motion (PCM) (Cervitech, Rockaway, NJ) cervical disk replacement, although originally invented by McAfee, has been continuously improved by Helmut Link and Arnold Keller, the same development group behind the Charité lumbar disc replacement. Its most unique biomechanical feature is the large radius UHMWPE bearing surface attached to the caudal endplate, allowing translational motion in an arc very consistent with the natural motion of the cervical spine segment. Its unconstrained nature and "press fit" osteoconductive endplate surfaces provide excellent primary fixation of both halves to the respective vertebrae. The porous ingrowth material is two ultra-thin layers of titanium with electrochemically coated Calcium Phosphate in a 1:1 ratio and is known by the tradename TiCaP (Huys Industries Limited, Toronto, Ontario, Canada). This is the same porous ingrowth surface that has been successfully utilized on the worldwide version of the Charité prosthesis (Waldemar Link GmbH & Co., Hamburg, Germany), except that the pore size has been reduced to more appropriately match the smaller bony trabecular architecture of the cervical vertebra compared to the lumbar vertebra. The press-fit Porsche-backed PCM prosthesis, PCM Corpectomy Replacement, and the Modular PCM Cervical prostheses are all manufactured by Cervitech, Inc. (300 Roundhill Drive, Rockaway, NJ, 07866, USA). The large, anatomically designed cobalt chrome endplates are shaped to maximize loading in the more dense lateral vertebral surfaces. Implantation is conducted in a traditional "endplate sparing" manner very consistent with the familiar Smith-Robinson ACDF technique, and using a special instrument that secures both prosthesis halves until their final release. It should be thought of as a "surface replacement" type of arthroplasty, which uses the surrounding muscles and ligaments to guide, restrain and limit joint motion rather than provide metal blocks to motion found in constrained prostheses.

Section snippets

Sample group

Between December 2002 and October 2003, 81 artificial cervical discs were implanted in 52 patients by cervical decompression using the Smith-Robinson standard anterior approach. Another patient in the same group was operated on using endoscopic techniques. The 53 patients were selected according to the following criteria:

Inclusion criteria:

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Patients 20 to 70 years of age
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Degenerative disc disease with radicular or medullary compression.

Exclusion criteria:

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Metabolic and bone diseases
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Patients in the

Benefits of the PCM prosthesis

The PCM prosthesis

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Enables a range of movement very similar to the normal cervical column
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Is easy to implant
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Requires no blood transfusion, because blood loss are imperceptible
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Can be implanted using endoscopic techniques
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Does not necessitate a large incision
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Requires minimum bone removal
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Produces excellent primary and secondary fixation
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Is compatible with magnetic resonance imaging for adjacent levels and CT for the operative level.

Results

Each patient was assessed and selected at the Mattos Pimenta Clinic outpatient surgery department. The clinical assessment was carried out on the basis of the Visual Analog Scale (VAS), Neck Disability Index (NDI) and Treatment Intensity Gradient Test (TIGT) scales. Static X-rays were requested of the cervical column in anteroposterior and lateral projections, and dynamic X-rays in flexion and extension, as well as nuclear magnetic resonance imaging of the cervical column.

Thirty-two of the 53

Analysis

We observed a marked decrease in pain intensity assessed on the VAS scale at 1-year follow-up compared with the preoperative score, as evidenced in Table 1 and Fig. 1.

With regard to the percentage of disability assessed on the NDI scale, there is likewise an appreciably significant improvement illustrated by the Table 2 and Fig. 2.

We noticed a decrease in the number of analgesic medications and rehabilitative medicine treatment modalities required to alleviate pain symptoms after disc

Conclusions

The neural decompression was a standard SmithRobinson type anterior cervical decompression followed by cervical arthroplasty. The procedure allows reconstruction of more unstable indications than previously reported with disc replacement. Eighteen PCM cases have been performed as complex revision procedures—1 previous Bryan Disc (Medtronic Sofamor Danek, Memphis, TN), 1 cage-plate, 3 patients had failed lordotic cervical cages, and 12 patients had presented with adjacent segment disease

Reference (1)

Tortolani JT, Cunningham B, Zorn C, Dmietriev A, McAfee PC. Intraesophageal retraction pressures—cervical disk...

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Prosthesis design and likelihood of achieving physiological range of motion after cervical disc arthroplasty: Analysis of range of motion data from 1,173 patients from 7 IDE clinical trials
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The functional goals of cervical disc arthroplasty (CDA) are to restore enough range of motion (ROM) to reduce the risk of accelerated adjacent segment degeneration but limit excessive motion to maintain a biomechanically stable index segment. This motion-range is termed the “Physiological mobility range.” Clinical studies report postoperative ROM averaged over all study subjects but they do not report what proportion of reconstructed segments yield ROM in the Physiological mobility range following CDA surgery.
To calculate the proportion of reconstructed segments that yield flexion-extension ROM (FE-ROM) in the Physiological mobility range (defined as 5-16 degrees) by analyzing the 24-month postoperative data reported by clinical trials of various cervical disc prostheses.
Analysis of 24-month postoperative FE-ROM data from clinical trials.
Data from 1,173 patients from single-level disc replacement clinical trials of 7 cervical disc prostheses.
24-month postoperative index-level FE-ROM.
The FE-ROM histograms reported in Food and Drug Administration-Investigational Device Exemption (FDA-IDE) submissions and available for this analysis were used to calculate the frequencies of implanted levels with postoperative FE-ROM in the following motion-ranges: Hypomobile [0–4 degrees], Physiological [5–16 degrees], and Hypermobile [≥17 degrees]. The ROM histograms also allowed calculation of the average ROM of implanted segments in each of the 3 motion-ranges.
Only 762 of 1,173 patients (implanted levels) yielded 24-month post-CDA FE-ROM in the physiological mobility range [5–16 degrees]. The proportions ranged from 60% to 79% across the 7 disc-prostheses, with an average of 65.0%±6.2%. Three-hundred and two (302) of 1,173 implanted levels yielded ROM in the 0–4-degree range. The proportions ranged from 15% to 38% with an average of 25.7%±8.9%. One-hundred and nine (109) of 1,173 implanted levels yielded ROM of ≥17 degrees with a range of 2%-21% and an average proportion of 9.3%±7.9%. The prosthesis with built-in stiffness due to its nucleus-annulus design yielded the highest proportion (103/131, 79%) of implanted segments in the physiological mobility range, compared to the cohort average of 65% (p<.01). Sixty-five of the 350 (18.6%) discs implanted with the 2 mobile-core designs in this cohort yielded ROM≥17 degrees as compared to the cohort average of 9.3% (109/1,173) (p<.05). At 2-year post-CDA, the “hypomobile” segments moved on average 2.4±1.2 degrees, those in the “physiological-mobility” group moved 9.4±3.2 degrees, and the hypermobile segments moved 19.6±2.6 degrees.
Prosthesis design significantly influenced the likelihood of achieving FE-ROM in the physiological mobility range, while avoiding hypomobility or hypermobility (p<.01). Postoperative ROM averaged over all study subjects provides incomplete information about the prosthesis performance - it does not tell us how many implanted segments achieve physiological mobility and how many end up with hypomobility or hypermobility. We conclude that the proportion of index levels achieving post-CDA motions in the physiological mobility range (5–16 degrees) is a more useful outcome measure for future clinical trials.
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At the 2 year follow up, there was no reoccurrence of symptoms. Outside of these reports, a few C7-T1 disc replacements have been included in larger studies on cervical disc replacement devices [10]. However, they do not include level specific data or discussion to add to the literature on C7-T1 disc replacements.
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We present a case series of seven consecutive patients who underwent CDR at C7-T1 by a single surgeon from January to December of 2019. There were five females and two males with an average age of 61.3 ± 6.4 years.
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We sought to determine the safety and effectiveness of the Flexible Cervical Implant in 1- or 2-level cervical segments.
Retrospective data collection was carried out on consecutive patients who underwent the implantation of the Flexible Cervical Implant in a local private health institution. Demographics, clinical pictures, magnetic resonance images, x-ray images, technical considerations, and postoperative clinical results were reviewed.
Twelve patients were treated with 15 implants. The mean age was 57.5 years (range 28–81), and 6 patients were males. The most common level was C5/C6 (7 cases). Radicular pain was the main symptom in all patients. Short-term postoperative clinical outcomes showed improvement in the visual analog scale (VAS) and the Neck Disability Index (NDI). The median VAS score for radicular pain improved from 6 to 2 (P < 0.001), whereas the median NDI showed a significant improvement from 25 to 5 (P < 0.001). No implant-related complications were reported. The mean follow-up was 7.3 months.
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FDA device/drug status: investigational/not approved (PCM artificial disc).

Support in whole or in part was received from Cervitech, a commercial entity. Authors acknowledge financial relationships (PCM stockholder for Cervitech; LP consultant for Cervitech; HDL board member for Cervitech), which may indirectly relate to the subject of this manuscript.

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Cervical Disc ReplacementClinical experience with the new artificial cervical PCM (Cervitech) disc