Anterior Longitudinal Ligament Reconstruction to Reduce Hypermobility of Cervical and Lumbar Disc Arthroplasty

The Decline of Lumbar Artificial Disc Replacement

Lower back pain associated with degenerative disc disease is a common occurrence, with many surgical treatments targeting the degenerated disc to relieve symptoms. Current surgical options for degenerative disc disease primarily consist of a discectomy followed by either spinal fusion or artificial disc replacement, with the former being increasingly more common in the lumbar region despite the risk of adjacent segment disease. Though artificial disc replacement aims to provide an increase in range of motion and decreases risk of adjacent segment disease, surgeons are increasingly opting for spinal fusion in the lumbar region. This review investigates underlying factors that may be contributing to this trend by assessing lumbar artificial disc replacement selection criteria, clinical outcomes, surgical technique, complications, revision burden, and overall cost. While these factors had some role in the physician's decision, ultimately the narrow selection criteria and lack of cost reimbursement by insurance has primarily led to the decline in lumbar artificial disc replacement.

Lumbar Total Disc Replacement Leads to Increased Subsequent Facet Injections Compared to Anterolateral Lumbar Interbody Fusions

STUDY DESIGN

Retrospective Matched Cohort.

OBJECTIVE

Despite known consequences to the facet joints following lumbar total disc replacement (TDR), there is limited data on facet injection usage for persistent postoperative pain. This study uses real-world data to compare the usage of therapeutic lumbar facet injections as a measure of symptomatic facet arthrosis following single-level, stand-alone TDR vs anterolateral lumbar interbody fusion (ALIF/LLIF).

METHODS

The PearlDiver database was queried for patients (2010-2021) with lumbar degenerative disc disease who received either a single-level, stand-alone TDR or ALIF/LLIF. All patients were followed for ≥2 years and excluded if they had a history of facet injections or spinal trauma, fracture, infection, or neoplasm. The two cohorts were matched 1:1 based on age, sex, insurance, year of operation, and medical comorbidities. The primary outcome was the use of therapeutic lumbar facet injections at 1-, 2-, and 5-year follow-up. Secondary outcomes included subsequent lumbar surgeries and surgical complications.

RESULTS

After 1:1 matching, each cohort had 1203 patients. Lumbar facet injections occurred significantly more frequently in the TDR group at 1-year (6.07% vs 1.66%, P < .0001), 2-year (8.40% vs 3.74%%, P < .0001), and 5-year (11.47% vs 6.40%, P < .0001) follow-up. 5-year injection-free probability curves demonstrated an 87.1% injection-free rate for TDR vs 92.9% for ALIF/LLIF. There was no clinical difference in the incidence of subsequent lumbar surgeries or complications.

CONCLUSION

Compared with ALIF/LLIF, patients who underwent TDR received significantly more facet injections, suggesting a greater progression of symptomatic facet arthrosis. TDR was not protective against reoperations compared to ALIF/LLIF.

Early Catastrophic Failure of Cervical Disc Arthroplasty: A Case Report

CASE

A 47-year-old healthy man underwent cervical disc arthroplasty (CDA) for a C6 radiculopathy. Two-week radiographs showed a well-positioned implant. At the 6-week postoperative visit, the inferior portion of the implant had displaced ventrally, with C6 anterior vertebral body collapse. The next day, the implant was removed and converted to a C5/6 anterior cervical discectomy and fusion. Bone biopsy was unremarkable.

CONCLUSIONS

This is the first reported case of early catastrophic failure of a well-positioned CDA in a healthy patient with good bone quality. Possible contributing mechanisms include hypermobility and anterior bone loss, factors previously associated with CDA.

Lumbar and cervical viscoelastic disc replacement: Concepts and current experience

The ideal lumbar and cervical discs should provide six degrees of freedom and tri-planar (three-dimensional) motion. Although all artificial discs are intended to achieve the same goals, there is considerable heterogeneity in the design of lumbar and cervical implants. The “second generation total disc replacements” are non-articulating viscoelastic implants aiming at the reconstruction of physiologic levels of shock absorption and flexural stiffness. This review aims to give an overview of the available implants detailing the concepts and the functional results experimentally and clinically. These monobloc prostheses raise new challenges concerning the choice of materials for the constitution of the viscoelastic cushion, the connection between the components of the internal structure and the metal endplates and even the bone anchoring mode. New objectives concerning the quality of movement and mobility control must be defined.

Cervical Disc Arthroplasty Migration Following Mechanical Intubation: A Case Presentation and Review of the Literature

BACKGROUND

Cervical arthroplasty has established itself as a safe and efficacious alternative to fusion in management of symptomatic cervical degenerative disease. Recent literature has indicated a trend toward decreased risk of reoperation with cervical arthroplasty, and reoperation in this subset commonly occurs secondary to recurrent pain and device-related complications. The instance of cervical arthroplasty migration, particularly in the setting of trauma, is particularly rare. Here, we report the first case of implant migration secondary to iatrogenic trauma following neck manipulation during direct laryngoscopy for mechanical intubation.

CASE DESCRIPTION

A 53-year-old smoker with cervical spondylosis underwent a cervical 3/4 arthroplasty with a ProDisc-C implant. About a month postoperatively, he was intubated via direct laryngoscopy for community acquired pneumonia and began experiencing new dysphonia and dysphagia after extubation. Delayed imaging revealed anterior migration of the implant. The patient immediately underwent removal of the implant and conversion to anterior cervical discectomy and fusion.

CONCLUSIONS

Supraphysiologic forces exerted through neck manipulation in mechanical intubation mimicked low-energy trauma, and in the setting of ligamentous resection necessary for cervical arthroplasty and inadequate osseous integration, led to migration of the implant. We recommend the integration of fiberoptic technique or video laryngoscopy with manual in line stabilization for intubation of post cervical arthroplasty patients when airway management is necessary within 10 months after cervical arthroplasty. Clinicians and anesthesiologists should have a high clinical suspicion for prompt and early workup with spine imaging in the setting of persistent postintubation symptoms such as dysphonia and/or dysphagia.

Multiobjective Design Optimization of a Biconcave Mobile-Bearing Lumbar Total Artificial Disk Considering Spinal Kinematics, Facet Joint Loading, and Metal-on-Polyethylene Contact Mechanics

Total disk arthroplasty (TDA) using an artificial disk (AD) is an attractive surgical technique for the treatment of spinal disorders, since it can maintain or restore spinal motion (unlike interbody fusion). However, adverse surgical outcomes of contemporary lumbar TDAs have been reported. We previously proposed a new mobile-bearing AD design concept featuring a biconcave ultrahigh-molecular-weight polyethylene (UHMWPE) mobile core. The objective of this study was to develop an artificial neural network (NN) based multiobjective optimization framework to refine the biconcave-core AD design considering multiple TDA performance metrics, simultaneously. We hypothesized that there is a tradeoff relationship between the performance metrics in terms of range of motion (ROM), facet joint force (FJF), and polyethylene contact pressure (PCP). By searching the resulting three-dimensional (3D) Pareto frontier after multiobjective optimization, it was found that there was a "best-tradeoff" AD design, which could balance all the three metrics, without excessively sacrificing each metric. However, for each single-objective optimum AD design, only one metric was optimal, and distinct sacrifices were observed in the other two metrics. For a commercially available biconvex-core AD design, the metrics were even worse than the poorest outcomes of the single-objective optimum AD designs. Therefore, multiobjective design optimization could be useful for achieving native lumbar segment biomechanics and minimal PCPs, as well as for improving the existing lumbar motion-preserving surgical treatments.

Artificial disc replacement in spine surgery

Total disc replacement (TDR) is an innovative procedure that has gained traction in spine surgery. A large amount of data in the literature report on the short-term outcomes of TDR surgery favorably. However, surgeons remain reluctant to opt for TDR surgery due to uncertainty of long-term outcomes. Recently, long term data regarding TDR surgery has become available, with some studies showing superior outcomes to fusion surgery. The goal of this review is to synthesize and clinically contextualize the recent literature on TDR surgery. This article also provides brief discussion of the biggest challenges currently facing disc arthroplasties and the ways in which they are being tackled.

Development of a Biconcave Mobile-Bearing Lumbar Total Disc Arthroplasty Concept Using Finite Element Analysis and Design Optimization

Total disc arthroplasty (TDA) is a motion-preserving surgical treatment for spinal disorders. However, adverse surgical outcomes, such as abnormal kinematics, facet joint (FJ) overloading, and polyethylene (PE) failures, have limited wide application of lumbar TDAs. The objectives of this computational study were to elucidate how implant design and FJ articulation both influence metal-on-polyethylene (MoP) motion and contact mechanics, as well as to propose and refine a new mobile-bearing TDA concept which enhanced postoperative performance. Simulation results show that abnormal motions (lift-off and/or unsymmetrical motion) are alleviated in fixed-/mobile-bearing TDA-treated segments, as the FJ gap increases. It clearly demonstrates that FJ articulation guides segmental motion and interferes with intended MoP articulation. For an existing biconvex mobile-bearing design, component impingement leads to a peak PE stress of 20.8 MPa (yield stress: 13 MPa), indicating a high risk of PE creep/fracture. Therefore, we proposed a new TDA concept featuring a biconcave PE core with a smooth shape, in order to strengthen the PE rim and mitigate edge-loading. Furthermore, the biconcave-core TDA was optimally designed to promote normal segmental range of motion (ROM), or to minimize polyethylene contact pressure (PCP). In extension (the severest loading scenario), the biconvex-core TDA design caused a ROM 3.6° (+88%) greater than the intact segment and a peak PCP of 116.5 MPa. In contrast, ROM-optimal or PCP-optimal biconcave-core TDA designs decreased the ROM difference to 0.0° or the peak PCP to 24.3 MPa. Therefore, this new TDA design can potentially reduce the incidence of hypermotion and PE damage. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1805-1816, 2019.

Lumbar Total Disc Replacement by the Lateral Approach-Up to 10 Years Follow-Up

OBJECTIVE

This study aimed to analyze radiologic and clinical results with a minimum 5 years follow-up (FUP) of lateral lumbar total disc replacement for the treatment of symptomatic lumbar degenerative disc disease.

METHODS

We performed a prospective, single-center, clinical, and radiologic study. Patients were treated with lumbar total disc replacement (extreme lateral total disc replacement) by a lateral transpsoas approach. From 2005 to 2012, 60 patients were enrolled (31 male, 29 female; total, 66 levels; average age, 42.8 years [standard deviation (SD), 9.7 years, range, 22-64 years]; mean body mass index, 26.0 [SD, 3.4]). Clinical end points included visual analog scale and Oswestry Disability Index questionnaires, complications, and reoperation. Radiographic end points included heterotopic ossification (McAfee classification), adjacent level disease, and prosthesis migration or subluxation.

RESULTS

The mean surgical duration was 122 minutes (SD, 45 minutes) with mean 58 mL (SD, 21 mL) of estimated blood loss. No intraoperative complication occurred. The exceptions were 1 patient with postanesthesia apnea and 2 patients with quadriceps motor deficit (resolved within 4 months with physiotherapy). Of 60 patients, 9 were missed to FUP and 51 (85%) were enrolled in the study, with mean FUP of 92 months (range, 60-122 months). In total, 5 levels (9%; 5 of 55) required to be fused. Both removal of the prostheses and interbody fusion were performed by the lateral transpsoas approach. One patient experienced CrCo allergy (at 2 months); 4 experienced persistent pain from different causes (at 7, 9, 24, and 88 months). Five patients (10%) presented with progression at adjacent levels and 2 (4%) required surgery. One patient required sacroiliac fusion at 63 months. There were no complications during the retrieval surgeries. One partial disc migration occurred but the patient refused retrieval. There was no bone bridging in 9% of the discs (grade 0 heterotopic ossification): grade I, 22%; grade II, 31%; grade III, 20%; grade IV (fusion), 18%. Most heterotopic ossification cases (93%) occurred in the lateral aspect of the disc space, and mostly at the contralateral side of the surgical approach. Patient-reported outcomes significantly improved (P < 0.01) at the last FUP. Visual analog scale back pain score was preoperatively 8.5, early postoperatively 2.5, and at last FUP 3.1. Oswestry Disability Index was preoperatively 55%, early postoperatively 31%, and at last FUP 21%.

CONCLUSIONS

This study presents mid-term to long-term results of extreme lateral total disc replacement artificial disc for the treatment of lumbar degenerative disease, with fast mobilization, sustained pain relief, and improved physical function. Despite the low rate of ALDis, some discs evolved to ankyloses and others were retrieved. Lumbar artificial disc replacement by the lateral approach seems to be a safe and effective treatment.