Cervical disc arthroplasty
In the USA between 2009 and 2017 the utilization of single-level cervical disc arthroplasty (CDA) rose from 5.6 cases for every 100 ACDFs performed in 2009 to 28.8 cases per 100 ACDFs in 2017. The most substantial increases occurred from 2013 onward. The region of highest utilization was the Mountain region (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming), where 14.3 CDAs were performed for every 100 ACDFs (averaged over the 9-year period of study). This is in contrast to the East South Central region (Alabama, Kentucky, Mississippi, and Tennessee), where only 2.1 CDAs were performed for every 100 ACDFs. Patient factors that significantly increased the odds of undergoing a CDR were age younger than 40 years (OR 15.9 [95% CI 10.0-25.5]; p < 0.001), no clinical evidence of myelopathy/myeloradiculopathy (OR 1.5 [95% CI 1.4-1.7]; p < 0.001), and a Charlson Comorbidity Index score of 0 (OR 2.7 [95% CI 1.7-4.2]; p < 0.001). After controlling for these factors, significant differences in utilization rates remained between regions (chi-square test = 830.4; p < 0.001) 1).
Total disc replacement is used for soft discal hernia resulting in cervicobrachial neuralgia.
Cervical artificial disc replacement (ADR) is supposed to preserve normal cervical range of motion than ACDF. A biomechanical measurement is necessary to identify the advantages and clinical implications of ADR. However, literature is scarce about this topic and in those available studies.
Three-dimensional motion analysis could provide useful information in an objective and quantitative way about cervical motion after surgery. In addition, it allowed to measure not only main motion but also coupled motion in three planes. ADR demonstrated better retained cervical motion mainly in sagittal plane (flexion and extension) and better preserved coupled sagittal and coronal motion during transverse plane motion than ACDF. ADR had the advantage in that it had the ability to preserve more cervical motions after surgery than ACDF 2).
Motion preserving anterior cervical disc arthroplasty (ACDA) in patients with cervical radiculopathy was introduced to prevent symptomatic cervical adjacent segment disease as compared to anterior cervical discectomy and fusion (ACDF).
1. position: supine, some use halter traction with this
a) microscope (not used by all surgeons)
3. implants: schedule vendor to provide a desired artificial disc
4. neuromonitoring: (optional) some surgeons used SSEP/MEP
5. consent (in lay terms for the patient—not all-inclusive):
a) procedure: surgery through the front of the neck to remove the degenerated disc and bone spurs, and to place an artificial disc
b) alternatives:nonsurgical management,surgical fusion(from the front or the back of the neck)
c) complications: swallowing difficulties are common but usually resolve, hoarseness of the voice (< 4% chance of it being permanent), injury to: foodpipe (esophagus), windpipe (trachea), arteries to the brain (carotid) with stroke, spinal cord with paralysis, nerve root with paralysis, possible seizures with MEPs (if used). The disc may eventually wear out and further surgery may be needed
1. no cervical collar (the goal is to preserve motion at the operated level)
2. NSAIDs around the clock for ≈ 2 weeks (this inhibits bone growth which theoretically helps avoid undesirable fusion at the operated level)
Anterior cervical disc arthroplasty versus anterior cervical discectomy and fusion
Cervical artificial disc replacement (ADR) is indicated for the treatment of severe radiculopathy permitting neural decompression and maintenance of motion.
The clinical and radiographic outcomes in cervical ADR patients using the ProDisc-C device (DePuy Synthes, West Chester, PA, USA) with a 5-9 year follow-up were collected through a prospective registry, with retrospective analysis performed on 24 consecutive patients treated with cervical ADR by a single surgeon. All patients underwent single- or two-level ADR with the ProDisc-C device. Outcome measures included neck and arm pain (visual analogue scale), disability (neck disability index [NDI]), complications and secondary surgery rates. Flexion-extension cervical radiographs were performed to assess range of motion (ROM) of the device and adjacent segment disease (ASD). Average follow-up was 7.7 years. Neck and arm pain improved 60% and 79%, respectively, and NDI had an improvement of 58%. There were no episodes of device migration or subsidence. Mean ROM of the device was 6.4°. Heterotopic ossification was present in seven patients (37%). Radiographic ASD below the device developed in four patients (21%) (one single-level and three two-level ADR). No patient required secondary surgery (repeat operations at the index level or adjacent levels). Fourteen out of 19 patients (74%) were able to return to employment, with a median return to work time of 1.3 months. The ProDisc-C device for cervical ADR is a safe option for patients providing excellent clinical outcomes, satisfactory return to work rates and maintenance of segmental motion despite radiographic evidence of heterotopic ossification and ASD on long-term follow-up 3).
Heterotopic ossification occurs in three-fourths of the patients after anterior cervical disc arthroplasty at two years after surgery, but does not necessarily correspond to clinical outcome, nor loss or preservation of ROM. The McAfee-Mehren classification should be combined with ROM evaluation to properly study HO 4).
Revision surgery and explantation
Between November 2008 and July 2016, 16 patients with prior implantation underwent removal of the Galileo-type disc prosthesis (Signus, Medizintechnik, Germany) due to a call back by industry. In 10 patients C-ADR was replaced with an alternative prosthesis, 6 patients received an ACDF. Duration of surgery, time to revision, surgical procedure, complication rate, neurological status, histological findings and outcome were examined in two institutions.
The C-ADR was successfully revised in all patients. Surgery was performed through the same anterior approach as the initial access. Duration of the procedure varied between 43 and 80min. Access-related complications included irritation of the recurrent nerve in one patient and mal-positioning of the C-ADR in another patient. Follow up revealed two patients with permanent mild/moderate neurologic deficits, NDI (neck disability index) ranged between 10 and 42%.
Anterior exposure of the cervical spine for explantation and revision of C-ADR performed through the initial approach has an overall complication rate of 18.75%. Replacements of the Galileo-type disc prosthesis with an alternative prosthesis or conversion to ACDF are both suitable surgical options without significant difference in outcome 5).