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PURPOSE: To describe modes of failure of cervical TDR, their related treatment strategies, and to describe a management strategy for the treatment of failed cervical TDR. METHODS: This retrospective study was based on a consecutive series of 53 cervical TDR patients who underwent removal or revision surgery. Chart review was conducted to collect general descriptive data, reasons for TDR removal/revision, duration from index implantation to re-operation, and the subsequent procedure performed. RESULTS: Among 53 patients, 36 underwent TDR removal and fusion, 16 underwent TDR removal and replacement with another TDR, and one patient's TDR was revised by repositioning. The mean duration from index surgery to removal/revision was 40.1 months (range: 3 days-222 months). In all cases, removal/revision surgery was completed without complication. The most common reason for removal was severe osteolysis, often involving C. acnes infection, and was primarily associated with one implant type. TDR removal and fusion were performed for subsidence, device migration, treatment of symptoms arising from posterior anatomy (facet joints, etc.), approach-related complications and pain. TDR replacement was feasible for hypermobility, metal allergy, implant locked in kyphosis, and oversized implant use. In one case of TDR malpositioning, the device was successfully revised into appropriate position. CONCLUSION: After cervical TDR failure, replacing a TDR with another implant can be feasible. Reasons for revision or removal after cervical TDR surgery include biomechanical failure, implant migration, surgeon or technical error, or biological reasons. The type of failure can help the surgeon create a strategy to address these complications.

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STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The purpose of this study was to investigate the rate of cervical total disc replacement (TDR) device removal or revision. BACKGROUND: Cervical TDR has gained acceptance as an alternative to anterior cervical discectomy and fusion in appropriately selected patients. There have been concerns over device safety, one measure of which is subsequent surgery related to device problems. PATIENTS AND METHODS: A consecutive series of 1626 patients undergoing cervical TDR from 2003 to June 2021 were included, consisting of TDRs up to 3 levels and hybrids (TDR and fusion). TDR removal or revision surgeries and reasons for these surgeries, procedures performed, and duration from index procedure were recorded. Data were analyzed to determine the removal/revision rate and factors possibly related to these events. RESULTS: There were 24 removals/revisions (1.48%) in the 1626 patients. Removal was performed in 23 cases (1.41%) and revision in 1 (0.06%). Among removal cases, anterior cervical discectomy and fusion was performed in 18 and TDR was replaced with another TDR in 5. Removals with fusion included 5 cases of osteolysis with/without Cutibacterium acnes , 4 device displacement/migration, 4 posterior spinal pathology, and one for each of the following: metal allergy, approach-related complications, malpositioning, subsidence, and hypermobility. The revision involved TDR repositioning 3 days after index surgery. There were 66 patients for whom a minimum of 10-year follow-up was confirmed, and none had removal/revision surgery 10 or more years after index surgery. There was no relationship between the occurrence of removal/revision and age, sex, body mass index, or physician experience (learning curve). The removal/revision rate was significantly higher in FDA trials versus postapproval (4.1% vs . 1.3%, P < 0.05). CONCLUSION: In this large consecutive series of patients, 1.48% of cervical TDRs were removed/revised. The low rate of removals/revisions over a long period of time provides support for the devices' safety. LEVEL OF EVIDENCE: Level IV.

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STUDY DESIGN: This was a retrospective study combined with attempted prospective patient contact to collect current data. OBJECTIVE: The purpose of this study was to investigate long-term clinical outcome of patients undergoing lumbar hybrid surgery (total disc replacement (TDR) at one level and fusion at an adjacent level. SUMMARY OF BACKGROUND DATA: Many patients with symptomatic lumbar disc degeneration are affected at more than one level. Lumbar TDR was introduced as a fusion alternative; however, some disc levels are not amenable to TDR and fusion is preferable at such levels. Hybrid surgery was introduced as an option to fusing multiple levels. METHODS: A consecutive series of 305 patients undergoing lumbar hybrid surgery was identified beginning with the first case experience in 2005. Operative and clinical outcome data including visual analog scales (VAS) assessing back and leg pain, Oswestry Disability Index (ODI), and re-operations were collected. The mean follow-up duration was 67.1 months. RESULTS: There were statistically significant improvements (P<0.01) in the mean values of all three clinical outcome measures: VAS back pain scores improved from 6.7 to 3.3; leg pain improved from 4.3 to 2.0; and ODI scores improved from 45.5 to 24.6. There were no significant differences in pain and function scores for patients with minimum 10-year follow-up vs. those with shorter follow-up duration. Re-operation occurred in 16.1% of patients, many of which involved removal of posterior instrumentation at the fusion level (6.2% of study group, 38.8% of re-operations). Re-operation involving the TDR level occurred in 9 patients (2.9%), only 3 of which (1.0%) involved TDR removal/revision. CONCLUSION: This study supports that for many patients with multilevel symptomatic disc degeneration, hybrid surgery is a viable surgical option. Significant improvements were demonstrated in pain and function scores with no diminished improvement in scores among patients with more than 10-year follow-up.

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STUDY DESIGN: This was a retrospective study with prospective patient contact attempted to collect current data. OBJECTIVE: The purpose was to investigate the incidence and reasons for lumbar total disk replacement (TDR) removal or revision. SUMMARY OF BACKGROUND DATA: A concern regarding lumbar TDR was safety, particularly the need for device removal or revision. This may be particularly important considering removal/revision requires repeat anterior exposure with an increased risk of vascular injury. METHODS: Data were collected for a series of 2141 lumbar TDR patients, beginning with the first case experience in 2000. The mean follow-up was 78.6 months. For each case of device removal/revision, the reason, duration from index surgery, and procedure performed were recorded. RESULTS: Of 2141 patients, 27 (1.26%) underwent TDR removal or revision. Device removal was performed in 24 patients (1.12%), while three patients underwent revision (0.14%). Of the 24 removals, 12 were due to migration and/or loosening, three developed problems post-trauma, two developed lymphocytic reaction to device materials, two had ongoing pain, and there was one case of each: TDR was too large, vertebral body fracture (osteoporosis), lytic lesion, device subsidence and facet arthrosis, and infection seeded from a chest infection 146 months post-TDR. The three revisions were for Core repositioning (technique error), device repositioning after displacement, and core replacement due to wear/failure. With respect to timing, 37.0% of removals/revisions occurred within one-month postimplantation. Of note, 40.7% of removals/revisions occurred in the first 25 TDR cases performed by individual surgeons. There was one significant vascular complication occurring in a patient whose TDR was removed due to trauma. This was also the only patient among 258 with ≥15-year follow-up who underwent removal/revision. CONCLUSION: In this large consecutive series, 1.26% of TDRs were removed/revised. The low rate over a 20 year period supports the safety of these devices.

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BACKGROUND: Anterior lumbar interbody fusion (ALIF) has been performed for many years. Often, posterior supplemental fixation has been used to provide additional stability to the operated segment. Interbody implants have evolved to incorporate unique designs, polyetheretherketone, integrated screws, and surface texture. With these changes, the need for supplemental posterior fixation has been debated. The purpose of this study was to evaluate the clinical outcome of stand-alone ALIF. METHODS: A surgery log was reviewed to identify the consecutive series of 58 patients undergoing ALIF using a STALIF stand-alone cage from March 2011 (first case) to December 2018 (minimum 24 months postoperative) with a mean follow-up of 30.6 months. All patients were treated for symptomatic degenerative conditions. Charts were reviewed to collect general patient information, operative data, and patient-reported outcomes, including the Oswestry Disability Index (ODI), visual analog scales (VAS) separately assessing back pain and leg pain, and re-operations. For patients who were not seen recently in clinic for follow-up, current outcome data were collected through mailings. RESULTS: The mean operative blood loss was 52.1 mL. There was a statistically significant improvement in mean ODI scores from 41.7 preoperatively to 21.0 at follow-up (P < 0.01). There was also significant improvement (P < 0.01) in VAS back pain (6.0-2.5) and leg pain (4.1-1.3). Subsequent surgery was performed on 9 patients. Reasons for re-operation were pseudoarthrosis (n = 3), progressive cage subsidence (n = 1), foraminal stenosis at the index level (n = 1), metal allergy reaction (n = 2), adjacent segment degeneration (n = 1), and ongoing pain (n = 1). There were no cases of device failure, vertebral body fracture, or screws backing out of the implant. DISCUSSION: Stand-alone ALIF was associated with statistically significant improvements in ODI scores, back pain, and leg pain. The re-operation rate for clear pseudoarthrosis or cage subsidence was 6.8%. These results support that stand-alone ALIF produces good outcomes in patients treated for symptomatic disc degeneration while avoiding the use of posterior fixation and its complication risk and cost. CLINICAL RELEVANCE: The results of this study support that stand-alone ALIF is a viable procedure for the treatment of symptomatic disc degeneration unresponsive in patients who have failed nonoperative care and who do not have specific indications for supplemental posterior instrumentation.

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PURPOSE: The purpose of this study was to investigate reasons and their frequency for why spine surgeons subspecializing in total disc replacement (TDR) performed lumbar fusion rather than TDR. METHODS: The study was based on a consecutive series of 515 patients undergoing lumbar TDR or fusion during a 5-year period by three surgeons specializing in TDR. For each fusion patient, the reason for not performing TDR was recorded. RESULTS: TDR was performed in 65.4% (n = 337) of patients and the remaining 34.6% (n = 178) underwent anterior lumbar interbody fusion (ALIF ± posterior instrumentation). Of the 178 fusion patients, the most common reason for fusion was combined factors related to severe degenerative changes (n = 59, 11.5% of the study population). The second most common reason was > Grade 1 spondylolisthesis (n = 32, 6.2%), followed by insurance non-coverage (n = 24, 4.7%), and osteopenia/osteoporosis (n = 13, 2.5%). Fusion patients were significantly older than TDR patients (52.5 vs. 41.6 years; p < 0.01). There was no significant difference with respect to gender (41.2% female vs. 43.8% female, p > 0.05) or the percentage of patients with single-level surgery (61.2% vs. 56.7%, p > 0.05). CONCLUSION: The most common reason for not performing lumbar TDR was related to anatomic factors that may compromise stability of the operated segment and/or TDR functionality. The older age of fusion patients may be related to these factors. This study found that many patients are appropriate candidates for lumbar TDR. However, even among TDR subspecialists, fusion is preferred when there are factors that cannot be addressed with TDR and/or may compromise implant functionality.

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STUDY DESIGN: Report of four collected cases. OBJECTIVE: The purpose of this report is to describe the presentation, diagnostic workup, treatment, and pathologic findings in four cases of lymphocytic reaction in patients receiving a metal-on-metal total disc replacement (TDR). SUMMARY OF BACKGROUND DATA: Metal-on-metal designs in hip arthroplasty have gained popularity because of decreased volumetric wear rates and theoretically increased implant longevity. Systemic metal ions produced have not been associated with adverse clinical sequelae, although there have been reports of local soft-tissue reactions leading to early prosthetic failure. Histologic evaluation in these cases suggested a cell-mediated delayed-type hypersensitivity reaction. Metal-on-metal bearings have also emerged in lumbar and cervical TDR. METHODS: This report is on four patients, from three centers, who underwent TDR, using a metal-on-metal implant, and later presented with symptoms that were determined to be due to lymphocytic reaction. Details of their symptoms, diagnostic work-up, treatment, and outcomes were compiled. RESULTS: All four patients initially had a good surgical outcome, followed by the onset and worsening of axial pain, and/or radicular symptoms months later. All patients had imaging findings of a mass lesion with neurologic impingement. All three of the lumbar patients underwent a decompressive posterior procedure before the eventual device removal and fusion. Intraoperatively, in all the lumbar cases, a thick, yellowish, avascular soft-tissue mass was found to be responsible for an epidural-mass effect on the thecal sac. In the cervical case, there was a gray-tinged soft-tissue response around the implant, suggestive of metallosis. Independent laboratory analysis confirmed a lymphocytic reaction to the implant. Three of the patients had a good outcome after the explant and revision surgery. The remaining patient continued to have residual symptoms related to the neural compression caused by the mass. CONCLUSIONS: In this group of patients from three centers, a metal-on-metal TDR resulted in a lymphocytic reaction causing subsequent failure of the surgery. This phenomenon has previously been recognized with metal bearings in hip arthroplasty. Surgeons using metal-on-metal TDRs should be aware of this possible occurrence.

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