Mechanical failure of the Mobi-C implant for artificial cervical disc replacement: report of 4 cases

View More View Less
  • 1 Department of Neurosurgery, University of California, Los Angeles;
  • | 2 Department of Neurosurgery, Scripps Memorial Hospital, La Jolla;
  • | 3 Long Beach Memorial Medical Center, Long Beach; and
  • | 4 Department of Orthopedic Surgery, Orthopedic Specialty Institute, Medical Group of Orange County, Orange, California
Free access

Cervical spondylosis is one of the most commonly treated conditions in neurosurgery. Increasingly, cervical disc replacement (CDR) has become an alternative to traditional arthrodesis, particularly when treating younger patients. Thus, surgeons continue to gain a greater understanding of short- and long-term complications of arthroplasty. Here, the authors present a series of 4 patients initially treated with Mobi-C artificial disc implants who developed postoperative neck pain. Dynamic imaging revealed segmental kyphosis at the level of the implant. All implants were locked in the flexion position, and all patients required reoperation. This is the first reported case series of symptomatic segmental kyphosis after CDR.

ABBREVIATIONS

ACDF = anterior cervical discectomy and fusion; CDR = cervical disc replacement; SSK = symptomatic segmental kyphosis.

Cervical spondylosis is one of the most commonly treated conditions in neurosurgery. Increasingly, cervical disc replacement (CDR) has become an alternative to traditional arthrodesis, particularly when treating younger patients. Thus, surgeons continue to gain a greater understanding of short- and long-term complications of arthroplasty. Here, the authors present a series of 4 patients initially treated with Mobi-C artificial disc implants who developed postoperative neck pain. Dynamic imaging revealed segmental kyphosis at the level of the implant. All implants were locked in the flexion position, and all patients required reoperation. This is the first reported case series of symptomatic segmental kyphosis after CDR.

The current common practice for patients with cervical disc disease is initial conservative therapy when appropriate, followed by anterior cervical discectomy and fusion (ACDF). Although the procedure is well tolerated, bony fusion often requires transient postoperative bracing and increases the risk of adjacent-level degeneration.1 In young, active patients with cervical disc herniation and myelopathy or radiculopathy, disc arthroplasty or cervical disc replacement (CDR) has become a popular surgical alternative. Not only does CDR maintain postoperative neck mobility at the involved levels (Table 1), but also it allows for rapid return to activity and offers less risk of adjacent-level degeneration.2,3

TABLE 1.

Comparison of selected FDA-approved artificial CDR devices*

Artificial CDR (manufacturer)FDA ApprovalDesignDegree of ConstrainmentAverage Range of Motion at 2 Yrs
Mobi-C (Zimmer Biomet)2013, 1- or 2-level3-piece, titanium coated, cobalt chrome endplates, unattached polyethylene coreUnconstrained10.2°
ProDisc-C (Centinel Spine, DePuy Synthes)2007, 1-level (C3–7)2-piece, titanium coated, cobalt chrome endplates w/ polyethylene core, attached to inferior endplate, ball & socketSemi-constrained9.4°
Prestige LP (Medtronic)2014, 1- or 2-level (C3–7)2-piece, titanium carbide ball & troughSemi-constrained7.5°
Bryan (Medtronic)2009, 1-level1-piece, 2 titanium alloy endplates, saline-filled polyurethane coreUnconstrained8.1°
M-6C (Spinal Kinetics, Orthofix)2019, 1-level1-piece, 2 titanium endplates, polycarbonate urethane coreSemi-constrainedUnavailable
Secure C3 (Globus)2012, 1-level (C3–7)3-piece, PEEK endplates, polyurethane coreSemi-constrained9.3°
PCM (NuVasive)2012, 1-level (C3–7)2-piece, cobalt chrome endplates, central polyethylene coreSemi-constrained5.2°

See Nunley et al. (2018),13 Choi et al. (2019),14 Sasso et al. (2008),15 Vaccaro et al. (2018),16 Leven et al. (2017),17 and Phillips et al. (2015).18

Despite the widespread adoption of arthroplasty by spine surgeons, the first FDA-approved cervical artificial disc, the PRESTIGE ST disc (Medtronic Inc.), was only approved in 2007. Few studies have examined long-term outcomes; however, two randomized clinical trials have reported lower failure rates at the index and adjacent levels for CDR than for ACDF for both one-level operations at 2 years’ follow-up4 and one- and two-level operations at 7 years’ follow-up.3 Reported rates of failure of CDR are low (mean 2.4%, range 0%–4.1%).2,5 Even less common are reported device failures, which include disc loosening, core or device migration, cracking of the implant’s outer sheath, and asymptomatic postoperative kyphosis.6–9 Nevertheless, device failure can result in patient pain or disability, additional surgery, and increased medical costs. One such device failure is symptomatic segmental kyphosis (SSK), in which the device tips anteriorly and becomes locked in the flexed position.4 A large case series reported a caudal CDR plate slipping anteriorly causing a fixed loss of lordosis, but limited details of the case were provided.3

Here, we report several cases of postoperative SSK after initial successful implantation of a commonly selected unconstrained CDR device, the Mobi-C cervical disc prosthesis (LDR Spine, Zimmer Biomet; approved August 7, 2013). This complication has not yet been reported in the literature as an indication for reoperation.

Three high-volume spine surgeons (T.H.L., F.J.C., D.Q.M.) in southern California were surveyed for their personal experience with arthroplasty and SSK. This survey revealed among these surgeons 4 cases out of 51 total Mobi-C CDRs (7.8%) that required reoperation because of rigid misalignment of the device in a flexed position after initial successful implantation. This particular complication was not seen with the other CDR devices used by these three surgeons, totaling 2725 non–Mobi-C CDR cases. The electronic medical record was accessed, and relevant clinical and radiographic data were collected. Shell angles were calculated on postoperative radiographic images by measuring the angle between the inferior and superior plates of the Mobi-C implant.

Case Reports

This report includes 4 male patients. The average age of the patients at presentation was 42.5 years. An average of 1.3 levels were treated per patient, with the most common segment being C5–6 (Table 2). Illustrative pre- and postoperative imaging and case descriptions are provided for each subject in Figs. 14. All patients had initially presented with cervical radiculopathy and had been treated conservatively.

TABLE 2.

Summary of 4 cases of mechanical failure of the Mobi-C implant

Case No.Age (yrs)SexPresentationMRILevelsShell AngleTime Btwn SurgeriesPostop SymptomsReoperationFU
126MNeck pain & lt arm pain unrelieved w/ physical therapy & nerve blocksHerniated disc at C5–6, eccentric to the ltC5–616°1 wkNeck pain w/o radiculopathyC5–6 ACDFResolution of all symptoms
248MNeck pain & bilat arm painC5–6 & C6–7 disc disease w/ mixed spondylotic complexC5–6 & C6–718°2.5 yrsNeck pain w/o radiculopathyC5–6 & C6–7 ACDFResolution of all symptoms
360MHistory of C5–T1 ACDF w/ neck & arm painSevere spondylosis & C4–5 herniated discC4–527°2.5 yrsNeck pain w/o radiculopathyC4–5 ACDFResolution of all symptoms
436MArm & neck painC5–6 herniated discC5–634°1 wkNeck pain w/o radiculopathyC5–6 Mobi-C disc replacementResolution of all symptoms

FU = follow-up.

FIG. 1.
FIG. 1.

Case 1. A 26-year-old man presented with neck pain and left arm pain unrelieved by physical therapy. MRI showed a noncalcified herniated disc at C5–6 (A) causing left neuroforaminal stenosis (B). Preoperative facet blocks at C5–6 bilaterally were ineffective. Preoperative cervical radiography showed good cervical range of motion without instability in flexion (C) and extension (D) and a relative lack of degenerative facet joint disease. Intraoperatively, the Mobi-C implant was appropriately positioned (E). One week after surgery, the patient complained of intractable localized neck pain without radiculopathy. He had no history of trauma. Radiography showed the Mobi-C device locked in fixed kyphosis in flexion (F) and extension (G). To restore lordosis, the patient underwent explantation of the misaligned Mobi-C artificial disc and arthrodesis of the C5–6 segment (H), with persistent complete resolution of neck pain and the original left C6 radiculopathy. Explantation and removal of the Mobi-C is facilitated using Caspar pin distraction and drilling of any obstructing endplate around the device. The decision to convert to fusion was based on intraoperative judgment of the feasibility of motion preservation after removal, which had been discussed with the patient preoperatively.

FIG. 2.
FIG. 2.

Case 2. A 48-year-old man presented with intractable neck pain and bilateral arm pain unrelieved by conservative therapy. MRI showed two-level C5–6 and C6–7 disc disease with mixed spondylotic complex (A) causing left neuroforaminal stenosis at C5–6 (B) and right neuroforaminal stenosis at C6–7 (C). Preoperative cervical radiography showed a moderate range of motion without instability in flexion (D) and extension (E) and a relative lack of major degenerative facet joint disease. Intraoperatively, the Mobi-C implants were appropriately positioned (F). Bilateral radiculopathy improved; however, the patient developed intractable neck pain 2.5 years postoperatively, at which time radiography showed the Mobi-C device locked in fixed kyphosis in flexion (G) and extension (H). Given the need for revision at two levels, C5–7 arthrodesis was discussed with the patient, which he agreed to (I), with complete resolution of neck pain.

FIG. 3.
FIG. 3.

Case 3. A 60-year-old man, whose history included multiple cervical arthrodeses culminating in a C5–T1 ACDF, presented with neck pain and left-greater-than-right arm pain unrelieved by conservative therapy. MRI showed a herniated disc at C4–5 above the fusion (A) causing left-greater-than-right neuroforaminal stenosis (B). The patient had done significant research on arthroplasty with the Mobi-C and ProDisc-C devices and was very hesitant to lose any more mobility in his neck given the significant fusion he had already undergone. He strongly believed that the position of his prior C5 fixation screws would impede optimal placement and stability of a C4–5 ProDisc-C device, and the surgeon was willing to place a Mobi-C device with the understanding that the failure rate might be higher for a CDR adjacent to such a large fusion mass. The patient was counseled that the lever arm created by the preexisting fusion mass would likely put increased strain on the CDR, just as it had led to increased degeneration and pathology at that level already. Preoperative cervical radiography showed good cervical range of motion without instability in flexion (C) and extension (D), and a relative lack of major degenerative facet joint disease. Intraoperatively, the Mobi-C implant was appropriately positioned (E). His symptoms improved; however, over 2 years after surgery, the patient complained of intractable localized neck pain without radiculopathy. Radiography showed the Mobi-C device locked in fixed kyphosis in flexion (F) and extension (G). The treatment was deemed to have failed with the arthroplasty potentially exacerbated by the fusion construct below, and the patient underwent explantation of the misaligned Mobi-C artificial disc and arthrodesis of the C4–5 segment (H) to avoid repeated CDR failure. The patient had persistent complete resolution of his neck pain.

FIG. 4.
FIG. 4.

Case 4. A 36-year-old athletic man presented with neck pain and radiculopathy unrelieved by conservative management. MRI showed a herniated disc at C5–6 (A) causing canal and neuroforaminal stenosis (B). Preoperative cervical radiography from another hospital showed good cervical range of motion without instability and a relative lack of degenerative facet joint disease (C). Intraoperatively, the Mobi-C implant was appropriately positioned (D). The patient had full resolution of neck pain and radiculopathy until 8 days after the surgery when he developed focal, intractable neck pain without radiculopathy. Radiography showed the Mobi-C device locked in fixed kyphosis (E), which was readily apparent on a simple lateral view. The patient was young and very active and strongly wanted to give the unconstrained CDR another chance before switching to a more constrained device or fusion. Intraoperatively, the template bone remained viable, so the patient underwent explantation of the misaligned Mobi-C artificial disc and replacement with another Mobi-C at C5–6 (F), with persistent resolution of neck pain. The device did not fail in the acute postoperative period the second time, and the patient has had a clinically and radiographically good long-term outcome.

After the failure of conservative management, all the patients underwent CDR with the Mobi-C implant, which is an unconstrained disc. All the patients participated in a preoperative discussion of the benefits and risks of cervical arthrodesis versus arthroplasty. Age, functional status, and abnormal ossification were all considered. Of note, in case 3 (Fig. 3), the patient had a very strong preference for a CDR since he feared having so much of his neck fused given his high functional status, and since he had researched and strongly preferred the less constrained Mobi-C device. The surgeon was upfront with the patient about the off-label application of the CDR adjacent to the fused C5–T1 segment and warned him that failure rates might be higher because of increased strain on the adjacent C4–5 level due to the long fused lever arm immediately below. The patient understood and nonetheless preferred the Mobi-C implant.

During the postoperative course, either shortly after surgery or at a delayed time, all patients reported neck pain without radiculopathy. Follow-up imaging revealed failure of the dynamic implant, which had become rigidly locked in an extreme flexed position in all cases (Figs. 1F, 1G, 2G, 2H, 3F, 3G, and 4E). The average shell angle was 23.8° (range 16°–34°). All patients underwent reoperation to remove the implant. Three patients were converted to anterior cervical fusion, and 1 patient (case 4; Fig. 4) strongly preferred to try the Mobi-C device again, despite counsel that the same risks for failure were present and that fusion or the use of a more constrained artificial disc was preferable. After the second surgery, all patients had complete resolution of symptoms. The average time between surgeries was 65.5 weeks (range 1–130 weeks).

Discussion

This case series illustrates SSK due to fixed-flexion hardware failure of Mobi-C CDR devices, which was relieved through reoperation with arthrodesis or revision disc arthroplasty. The average time to repeat surgery for SSK was 65.5 weeks, with a bimodal distribution. Two patients underwent reoperation for SSK immediately (approximately 1 week after their first surgery), and 2 patients underwent repeat surgery in a delayed fashion (approximately 2.5 years after their first surgery). Given the bimodal distribution of presenting symptoms, there may be inherently different etiologies responsible for early versus delayed failure.

All three surgeons surveyed for this study are experienced and regularly perform CDR with good results. However, early SSK could be attributable to suboptimal intraoperative positioning of the implant in kyphosis, predisposing the superior plate to slip and lock anteriorly upon axial weight bearing. Although a suboptimal technique is possible, intraoperative fluoroscopy for all cases was reviewed and showed parallel endplates with no gross misalignment at the time of insertion (Figs. 1E, 2F, 3E, and 4D). Notably, in case 4, in which the failed Mobi-C implant had been replaced with another Mobi-C device given the strong patient preference and viable bony endplate quality, an upright weight-bearing radiograph showed parallel, symmetric alignment of the CDR endplates within 24 hours of the reoperation. The replacement Mobi-C device has not failed to date, unlike the first Mobi-C device, which failed 1 week postoperatively in this same patient. This result likely rules out patient factors as the underlying cause of failure and may speak to the increased need to have a very precise surgical technique to prevent anterior slippage of the endplate and SSK in unconstrained CDR devices. Such a high degree of precision is generally not required for a standard ACDF, which is less sensitive to minor deviations off midline, endplate quality, and, as these cases suggest, top and bottom endplates that are not perfectly parallel and aligned with one another. This last risk factor for SSK may be higher with unconstrained artificial discs, such as the Mobi-C, which are three-piece designs. The mobile core is separate from the two metal endplates, which can cause hypermobility or dislocation of the core. By contrast, constrained CDR devices are often two-piece designs with the core incorporated into one of the metal endplates. The fixed core cannot dislodge or allow for hypermobility, making SSK much less likely.

Delayed SSK may result more from patient selection or chronic device failure factors than from surgical technique. First, the intrinsic laxity of a patient’s facet capsules or preexisting cervical kyphosis may precipitate implant failure. In our series, the patients with delayed SSK had normal preoperative flexion-extension cervical radiographs (Figs. 2 and 3). Second, for the Mobi-C device, the mobile bearing within the device flexes beyond the normal physiological range of motion.10 The increased mobility of an unconstrained core places more strain on the facet joints than more constrained devices and thus, in theory, could predispose to SSK over time. This may have been exacerbated in case 3 (Fig. 3) given placement of the CDR above a large fusion construct with increased strain on the adjacent level. This may have also contributed to failure in case 2 (Fig. 2) in which two CDRs were implanted adjacent to one another, potentially exaggerating the hypermobility in the low cervical spine leading to premature failure. Third, mechanical failure is also possible with inadvertent locking of the CDR in extreme flexion. The greatest likelihood is that the precise etiology of either early or delayed SSK in each of our patients is multifactorial with a significant contribution from the surgical technique for early failure and from patient selection for delayed failure.

The primary symptom after initial surgery for all patients in this study was neck pain without radiculopathy. Standard anteroposterior radiographic imaging of the cervical spine suggested device failure and SSK, which was then confirmed on lateral flexion-extension imaging when available. Dynamic imaging can be critically important in diagnosing postoperative SSK. We advocate obtaining flexion-extension radiographs in all postoperative patients who have neck pain after cervical arthroplasty if no other pathology is apparent on a simple two-view radiograph of the cervical spine.

The published literature on SSK is limited. One case series has reported 13 separate cases of uniform mild focal kyphosis of 4.7° in single-level cervical arthroplasty with the Bryan artificial disc (Medtronic Inc.) due to endplate milling that reorients the endplates.7 The device shell angle of fixed SSK in our series was 23.8°, which is greater than any previously reported asymptomatic segmental kyphosis after CDR. Other case series have not been able to show a clear statistical correlation between clinical symptomatic outcome questionnaires (Neck Disability Index and SF-36) and postoperative cervical kyphosis.11 In our series, all patients had resolution of symptoms after correction of postoperative SSK. Thus, we strongly advocate urgent surgical treatment of SSK either by CDR replacement or by arthrodesis.12

Given the increasing use of CDR, surgeons should be aware of all potential complications. SSK causes pain, requires additional surgery, increases medical costs, and potentially results in fusion. Furthermore, given that delayed CDR failure can be precipitated by patient factors, surgeons should carefully select patients for these implants and reconsider CDR in those with evidence of laxity or hypermobility on preoperative flexion-extension radiographs. This case series additionally supports the need for a more precise surgical technique with CDR than with ACDF. Without parallel alignment of the endplates, an unconstrained CDR device may be vulnerable to SSK. The cases presented here exclusively involved the Mobi-C implant and may represent an opportunity for improvement of the implant design and function. Of note, all surgeons surveyed for this case series continue to perform CDR, albeit with an improved appreciation for the diagnosis and treatment of SSK.

Conclusions

CDR remains an alternative to cervical arthrodesis for select, especially younger, high-functioning patients. Hardware failure with fixed SSK can occur either immediately following surgery or in a more delayed fashion. We recommend increased vigilance with the surgical technique and patient selection as well as dynamic cervical radiographs for all patients who present with neck pain after CDR. If SSK is diagnosed, either replacement of the artificial disc or conversion to cervical fusion can resolve patient symptoms.

Acknowledgments

Dr. DiCesare had funding from an institutional NIH R25 grant during completion of this paper.

Disclosures

Dr. Lanman is a consultant for and has royalty arrangements with Medtronic. Dr. McBride is a consultant for Centinal Spine.

Author Contributions

Conception and design: McBride, DiCesare, Tucker, Lanman, Coufal. Acquisition of data: McBride, DiCesare, Tucker, Say, Lanman, Coufal, Millard, Deckey, Shetgeri. Analysis and interpretation of data: McBride, DiCesare, Tucker, Say, Patel. Drafting the article: DiCesare, Tucker, Shetgeri. Critically revising the article: McBride, DiCesare, Say, Patel, Lanman, Coufal, Millard, Deckey, Shetgeri. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: McBride. Statistical analysis: DiCesare, Say. Administrative/technical/material support: McBride, DiCesare, Tucker, Say. Study supervision: McBride, DiCesare, Tucker.

References

  • 1

    Hilibrand AS, Carlson GD, Palumbo MA, et al. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 1999;81(4):519528.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2

    Skovrlj B, Lee D-H, Caridi JM, Cho SK-W. Reoperations following cervical disc replacement. Asian Spine J. 2015;9(3):471482.

  • 3

    Radcliff K, Davis RJ, Hisey MS, et al. Long-term evaluation of cervical disc arthroplasty with the Mobi-C© cervical disc: a randomized, prospective, multicenter clinical trial with seven-year follow-up. Int J Spine Surg. 2017;11:31.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4

    Hisey MS, Bae HW, Davis R, et al. Multi-center, prospective, randomized, controlled investigational device exemption clinical trial comparing Mobi-C Cervical Artificial Disc to anterior discectomy and fusion in the treatment of symptomatic degenerative disc disease in the cervical spine. Int J Spine Surg. 2014;8:8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5

    Cardoso MJ, Rosner MK. Multilevel cervical arthroplasty with artificial disc replacement. Neurosurg Focus. 2010;28(5):E19.

  • 6

    Cao J-M, Zhang Y-Z, Shen Y, Ding W-Y. Complications of Bryan cervical disc replacement. Orthop Surg. 2010;2(2):8693.

  • 7

    Johnson JP, Lauryssen C, Cambron HO, et al. Sagittal alignment and the Bryan cervical artificial disc. Neurosurg Focus. 2004;17(6):E14.

  • 8

    Pitsika M, Nissen J. Spinal cord compression due to nucleus migration from Mobi-C total disc replacement. Br J Neurosurg. Published online January 24, 2020. doi:10.1080/02688697.2020.1716942

    • Search Google Scholar
    • Export Citation
  • 9

    Park J-B, Chang H, Yeom JS, et al. Revision surgeries following artificial disc replacement of cervical spine. Acta Orthop Traumatol Turc. 2016;50(6):610618.

  • 10

    Sekhon LHS. Cervical arthroplasty in the management of spondylotic myelopathy: 18-month results. Neurosurg Focus. 2004;17(3):E8.

  • 11

    Pickett GE, Mitsis DK, Sekhon LH, et al. Effects of a cervical disc prosthesis on segmental and cervical spine alignment. Neurosurg Focus. 2004;17(3):E5.

  • 12

    Pickett GE, Sekhon LHS, Sears WR, Duggal N. Complications with cervical arthroplasty. J Neurosurg Spine. 2006;4(2):98105.

  • 13

    Nunley PD, Coric D, Frank KA, Stone MB. Cervical disc arthroplasty: current evidence and real-world application. Neurosurgery. 2018;83(6):10871106.

  • 14

    Choi H, Baisden JL, Yoganandan N. A comparative in vivo study of semi-constrained and unconstrained cervical artificial disc prostheses. Mil Med. 2019;184(suppl 1):637643.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Sasso RC, Best NM, Metcalf NH, Anderson PA. Motion analysis of Bryan cervical disc arthroplasty versus anterior discectomy and fusion: results from a prospective, randomized, multicenter, clinical trial. J Spinal Disord Tech. 2008;21(6):393399.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Vaccaro A, Beutler W, Peppelman W, et al. Long-term clinical experience with selectively constrained SECURE-C cervical artificial disc for 1-level cervical disc disease: results from seven-year follow-up of a prospective, randomized, controlled investigational device exemption clinical trial. Int J Spine Surg. 2018;12(3):377387.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Leven D, Meaike J, Radcliff K, Qureshi S. Cervical disc replacement surgery: indications, technique, and technical pearls. Curr Rev Musculoskelet Med. 2017;10(2):160169.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Phillips FM, Geisler FH, Gilder KM, et al. Long-term outcomes of the US FDA IDE prospective, randomized controlled clinical trial comparing PCM cervical disc arthroplasty with anterior cervical discectomy and fusion. Spine (Phila Pa 1976). 2015;40(10):674683.

    • Crossref
    • Search Google Scholar
    • Export Citation
Images from Wemhoff et al. (pp 751–756).
  • View in gallery

    Case 1. A 26-year-old man presented with neck pain and left arm pain unrelieved by physical therapy. MRI showed a noncalcified herniated disc at C5–6 (A) causing left neuroforaminal stenosis (B). Preoperative facet blocks at C5–6 bilaterally were ineffective. Preoperative cervical radiography showed good cervical range of motion without instability in flexion (C) and extension (D) and a relative lack of degenerative facet joint disease. Intraoperatively, the Mobi-C implant was appropriately positioned (E). One week after surgery, the patient complained of intractable localized neck pain without radiculopathy. He had no history of trauma. Radiography showed the Mobi-C device locked in fixed kyphosis in flexion (F) and extension (G). To restore lordosis, the patient underwent explantation of the misaligned Mobi-C artificial disc and arthrodesis of the C5–6 segment (H), with persistent complete resolution of neck pain and the original left C6 radiculopathy. Explantation and removal of the Mobi-C is facilitated using Caspar pin distraction and drilling of any obstructing endplate around the device. The decision to convert to fusion was based on intraoperative judgment of the feasibility of motion preservation after removal, which had been discussed with the patient preoperatively.

  • View in gallery

    Case 2. A 48-year-old man presented with intractable neck pain and bilateral arm pain unrelieved by conservative therapy. MRI showed two-level C5–6 and C6–7 disc disease with mixed spondylotic complex (A) causing left neuroforaminal stenosis at C5–6 (B) and right neuroforaminal stenosis at C6–7 (C). Preoperative cervical radiography showed a moderate range of motion without instability in flexion (D) and extension (E) and a relative lack of major degenerative facet joint disease. Intraoperatively, the Mobi-C implants were appropriately positioned (F). Bilateral radiculopathy improved; however, the patient developed intractable neck pain 2.5 years postoperatively, at which time radiography showed the Mobi-C device locked in fixed kyphosis in flexion (G) and extension (H). Given the need for revision at two levels, C5–7 arthrodesis was discussed with the patient, which he agreed to (I), with complete resolution of neck pain.

  • View in gallery

    Case 3. A 60-year-old man, whose history included multiple cervical arthrodeses culminating in a C5–T1 ACDF, presented with neck pain and left-greater-than-right arm pain unrelieved by conservative therapy. MRI showed a herniated disc at C4–5 above the fusion (A) causing left-greater-than-right neuroforaminal stenosis (B). The patient had done significant research on arthroplasty with the Mobi-C and ProDisc-C devices and was very hesitant to lose any more mobility in his neck given the significant fusion he had already undergone. He strongly believed that the position of his prior C5 fixation screws would impede optimal placement and stability of a C4–5 ProDisc-C device, and the surgeon was willing to place a Mobi-C device with the understanding that the failure rate might be higher for a CDR adjacent to such a large fusion mass. The patient was counseled that the lever arm created by the preexisting fusion mass would likely put increased strain on the CDR, just as it had led to increased degeneration and pathology at that level already. Preoperative cervical radiography showed good cervical range of motion without instability in flexion (C) and extension (D), and a relative lack of major degenerative facet joint disease. Intraoperatively, the Mobi-C implant was appropriately positioned (E). His symptoms improved; however, over 2 years after surgery, the patient complained of intractable localized neck pain without radiculopathy. Radiography showed the Mobi-C device locked in fixed kyphosis in flexion (F) and extension (G). The treatment was deemed to have failed with the arthroplasty potentially exacerbated by the fusion construct below, and the patient underwent explantation of the misaligned Mobi-C artificial disc and arthrodesis of the C4–5 segment (H) to avoid repeated CDR failure. The patient had persistent complete resolution of his neck pain.

  • View in gallery

    Case 4. A 36-year-old athletic man presented with neck pain and radiculopathy unrelieved by conservative management. MRI showed a herniated disc at C5–6 (A) causing canal and neuroforaminal stenosis (B). Preoperative cervical radiography from another hospital showed good cervical range of motion without instability and a relative lack of degenerative facet joint disease (C). Intraoperatively, the Mobi-C implant was appropriately positioned (D). The patient had full resolution of neck pain and radiculopathy until 8 days after the surgery when he developed focal, intractable neck pain without radiculopathy. Radiography showed the Mobi-C device locked in fixed kyphosis (E), which was readily apparent on a simple lateral view. The patient was young and very active and strongly wanted to give the unconstrained CDR another chance before switching to a more constrained device or fusion. Intraoperatively, the template bone remained viable, so the patient underwent explantation of the misaligned Mobi-C artificial disc and replacement with another Mobi-C at C5–6 (F), with persistent resolution of neck pain. The device did not fail in the acute postoperative period the second time, and the patient has had a clinically and radiographically good long-term outcome.

  • 1

    Hilibrand AS, Carlson GD, Palumbo MA, et al. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 1999;81(4):519528.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2

    Skovrlj B, Lee D-H, Caridi JM, Cho SK-W. Reoperations following cervical disc replacement. Asian Spine J. 2015;9(3):471482.

  • 3

    Radcliff K, Davis RJ, Hisey MS, et al. Long-term evaluation of cervical disc arthroplasty with the Mobi-C© cervical disc: a randomized, prospective, multicenter clinical trial with seven-year follow-up. Int J Spine Surg. 2017;11:31.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4

    Hisey MS, Bae HW, Davis R, et al. Multi-center, prospective, randomized, controlled investigational device exemption clinical trial comparing Mobi-C Cervical Artificial Disc to anterior discectomy and fusion in the treatment of symptomatic degenerative disc disease in the cervical spine. Int J Spine Surg. 2014;8:8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5

    Cardoso MJ, Rosner MK. Multilevel cervical arthroplasty with artificial disc replacement. Neurosurg Focus. 2010;28(5):E19.

  • 6

    Cao J-M, Zhang Y-Z, Shen Y, Ding W-Y. Complications of Bryan cervical disc replacement. Orthop Surg. 2010;2(2):8693.

  • 7

    Johnson JP, Lauryssen C, Cambron HO, et al. Sagittal alignment and the Bryan cervical artificial disc. Neurosurg Focus. 2004;17(6):E14.

  • 8

    Pitsika M, Nissen J. Spinal cord compression due to nucleus migration from Mobi-C total disc replacement. Br J Neurosurg. Published online January 24, 2020. doi:10.1080/02688697.2020.1716942

    • Search Google Scholar
    • Export Citation
  • 9

    Park J-B, Chang H, Yeom JS, et al. Revision surgeries following artificial disc replacement of cervical spine. Acta Orthop Traumatol Turc. 2016;50(6):610618.

  • 10

    Sekhon LHS. Cervical arthroplasty in the management of spondylotic myelopathy: 18-month results. Neurosurg Focus. 2004;17(3):E8.

  • 11

    Pickett GE, Mitsis DK, Sekhon LH, et al. Effects of a cervical disc prosthesis on segmental and cervical spine alignment. Neurosurg Focus. 2004;17(3):E5.

  • 12

    Pickett GE, Sekhon LHS, Sears WR, Duggal N. Complications with cervical arthroplasty. J Neurosurg Spine. 2006;4(2):98105.

  • 13

    Nunley PD, Coric D, Frank KA, Stone MB. Cervical disc arthroplasty: current evidence and real-world application. Neurosurgery. 2018;83(6):10871106.

  • 14

    Choi H, Baisden JL, Yoganandan N. A comparative in vivo study of semi-constrained and unconstrained cervical artificial disc prostheses. Mil Med. 2019;184(suppl 1):637643.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Sasso RC, Best NM, Metcalf NH, Anderson PA. Motion analysis of Bryan cervical disc arthroplasty versus anterior discectomy and fusion: results from a prospective, randomized, multicenter, clinical trial. J Spinal Disord Tech. 2008;21(6):393399.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Vaccaro A, Beutler W, Peppelman W, et al. Long-term clinical experience with selectively constrained SECURE-C cervical artificial disc for 1-level cervical disc disease: results from seven-year follow-up of a prospective, randomized, controlled investigational device exemption clinical trial. Int J Spine Surg. 2018;12(3):377387.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Leven D, Meaike J, Radcliff K, Qureshi S. Cervical disc replacement surgery: indications, technique, and technical pearls. Curr Rev Musculoskelet Med. 2017;10(2):160169.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Phillips FM, Geisler FH, Gilder KM, et al. Long-term outcomes of the US FDA IDE prospective, randomized controlled clinical trial comparing PCM cervical disc arthroplasty with anterior cervical discectomy and fusion. Spine (Phila Pa 1976). 2015;40(10):674683.

    • Crossref
    • Search Google Scholar
    • Export Citation

Metrics

All Time Past Year Past 30 Days
Abstract Views 1649 0 0
Full Text Views 2569 2173 196
PDF Downloads 2617 2295 178
EPUB Downloads 0 0 0