Tag: Total disc replacement

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Erector spinae plane block during standalone anterior lumbar surgery: impact on early ambulation, length of stay, and inpatient opioid use

J Neurosurg Spine 44:90–98, 2026

This clinical retrospective study assesses the impact of erector spinae plane block (ESPB) as an adjunct to multimodal analgesia in standalone anterior lumbar procedures (ALIF and lumbar TDR). Outcomes compared between ESPB and non-ESPB cohorts include in-hospital pain scores, opioid consumption (MME), time to ambulation, length of stay (LOS), and opioid-related complications.

Results show ESPB associated with lower day-of-surgery pain scores, earlier ambulation, and shorter LOS, with reduced in-hospital oral MME in univariate analysis; preoperative opioid use predicted higher perioperative opioid consumption and urinary retention despite ESPB. The authors emphasize ESPB as a component of enhanced recovery protocols and note limitations of retrospective design and sample size.

Erector Spinae Plane Block (ESPB): ESPB is a regional analgesic technique used as an adjunct in anterior-only lumbar surgeries, such as ALIF and total disc replacement, aiming to improve perioperative pain control and recovery outcomes.

Reduced Pain and Opioid Use: ESPB significantly lowers pain scores on the day of surgery and reduces in-hospital opioid use, especially oral morphine milligram equivalents (MMEs), compared to patients not receiving ESPB.

Shorter Hospital Stay: Patients receiving ESPB experience a significantly shorter hospital length of stay (LOS) and are more likely to be discharged earlier, including same-day discharge, than those without ESPB.

Faster Ambulation: ESPB is associated with a significantly shorter time to first ambulation after surgery, facilitating earlier rehabilitation.

Predictors of Opioid Use: Baseline (preoperative) opioid use is the strongest predictor of higher perioperative opioid requirements and is also linked to a higher incidence of postoperative urinary retention, regardless of ESPB administration.

Subgroup Benefits: Among ESPB patients, those with a shorter LOS (<2 days) had earlier ambulation, lower opioid use, and lower pain scores on postoperative day 1, indicating enhanced early recovery.

Multimodal Pain Management: ESPB should be considered as one component within a comprehensive multimodal pain management strategy (such as ERAS protocols), rather than as a standalone intervention.

Study Limitations: The findings are limited by the retrospective design, potential selection bias, lack of randomization, and incomplete data on preoperative opioid use, highlighting the need for larger, prospective studies

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The First Grade III Lumbar Spondylolisthesis Treated With the Novel 360° Artificial Disc/Artificial Facet Replacement Solution

Int J Spine Surg 2025, 19 (4) 362-369

This case report describes the first use of a combined 360° motion-preserving surgery—utilizing Prodisc L Artificial Disc and TOPS facet replacement—for grade III lumbar spondylolisthesis, showing rapid pain relief, improved function, and high patient satisfaction, suggesting a potential alternative to spinal fusion for select patients.

• First reported case of grade III lumbar spondylolisthesis treated with a novel 360° motion-preserving solution combining Prodisc L Artificial Disc Replacement and the Premia TOPS System.

• Traditional treatment is spinal fusion, but it reduces motion and can cause adjacent segment disease, especially problematic for younger, active patients.

• The patient, a 36-year-old man with progressive L5-S1 grade III spondylolisthesis and severe disc collapse, had failed conservative therapy and declined fusion.

• Surgery was performed in two stages: anterior artificial disc replacement, followed by posterior facet replacement with the TOPS device.

• Significant improvements were seen in pain, function, and satisfaction, with the patient pain-free and highly satisfied by 3 and 9 months post-op.

• This case suggests the 360° arthroplasty approach may offer a motion-preserving alternative to fusion for high-grade spondylolisthesis.

• Further research and long-term data are needed to confirm safety, durability, and broader effectiveness.

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Failure in cervical total disc arthroplasty

The Spine Journal 22 (2022) 353−369

Cervical total disc arthroplasty (TDA) is an alternative procedure to anterior cervical discectomy and fusion that facilitates neural decompression while both preserving motion of the spinal unit and decreasing the risk for degenerative changes at adjacent segments. However, due to its more recent introduction in clinical practice and low complication rates, the modes by which TDA may fail remain to be described.

PURPOSE: This study sought to identify the modes and frequencies of cervical TDA failure in order to propose a novel classification system.

STUDY DESIGN: Retrospective cohort and systematic review.

PATIENT SAMPLE: Patients who underwent single or two-level TDA for cervical radiculopathy or myelopathy at a single institution and in the literature of medium and large prospective studies. OUTCOME MEASURES: Cervical TDA failure, defined as subsequent surgical intervention at the index segment.

METHODS: This study retrospectively reviewed patients who underwent single or two-level TDA for cervical radiculopathy or myelopathy at a single institution to identify the potential implant failure modes. A systematic review and meta-analysis of prospective data in the literature was then performed to further supplement failure mode identification and to describe the rates at which the various failure types occurred. Statistical analysis included betweengroup comparisons of Non-Failed and Failed patients and frequencies of each failure type among Failed patients.

RESULTS: A retrospective review at our institution of 169 patients (201 levels) identified eight failures, for a failure rate of 4.7%. Additionally, seven patients were revised who had the primary surgery at an outside institution. The systematic review of 3976 patients (4525 levels) identified 165 (4.1%) additional failures. Using this data, six primary failure types were classified, with several subtypes. These include recurrent or persistent index-level stenosis (Type I); migration (Type II) presenting as gross extrusion (A) or endplate failure with subsidence/acute fracture (B); instability (Type III) due to mechanical loosening (A), septic loosening (B), or device fracture (C); device motion loss (Type IV) such as “locking” of the device in kyphosis; implantation error (Type V) due to malposition (A) or improper sizing (B); and wear (Type VI) either without osteolysis (A) or with wear-particle-induced osteolysis (B). Stenosis (Type I) was the most common mode of failure found both through retrospective review and in the literature.

CONCLUSIONS: Cervical TDA fails through six primary mechanisms. While rates of certain failures requiring subsequent surgical intervention are low, it is possible that these complications may become more prevalent upon further longitudinal observation. Thus, future application and validation of this classification system is warranted to evaluate how failure frequencies change over time and with larger patient samples. © 2021 Elsevier Inc. All rights reserved.

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Ten-Year Outcomes of 1- and 2-Level Cervical Disc Arthroplasty From the Mobi-C Investigational Device Exemption Clinical Trial

Neurosurgery 88:497–505, 2021

Short- and mid-term studies have shown the effectiveness of cervical disc arthroplasty (CDA) to treat cervical disc degeneration.

OBJECTIVE: To report the 10-yr outcomes of a multicenter experience with cervical arthroplasty for 1- and 2-level pathology.

METHODS: This was a prospective study of patients treated with CDA at 1 or 2 contiguous levels using the Mobi-C ®  Cervical Disc (Zimmer Biomet).  Following completion of the 7-yr Food and Drug Administration postapproval study, follow-up continued to 10 yr for consenting patients at 9 high-enrolling centers. Clinical and radiographic endpoints were collected out to 10 yr.

RESULTS: At 10 yr, patients continued to have significant improvement over baseline Neck Disability Index (NDI), neck and arm pain, neurologic function, and segmental range of motion (ROM). NDI and pain outcomes at 10 yr were significantly improved from 7 yr. Segmental and global ROM and sagittal alignment also were maintained from 7 to 10 yr. Clinically relevant adjacent segment pathology was not significantly different between 7 and 10 yr. The incidence of motion restricting heterotopic ossification at 10 yr was not significantly different from 7 yr for 1-level (30.7% vs 29.6%) or 2-level (41.7% vs 39.2%) patients. Only 2 subsequent surgeries were reported after 7 yr.

CONCLUSION: Our results through 10 yr were comparable to 7-yr outcomes, demonstrating that CDA with Mobi-C ® continues to be a safe and effective surgical treatment for patients with 1- or 2-level cervical degenerative disc disease.

 

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Heterotopic ossification and radiographic adjacent-segment disease after cervical disc arthroplasty

J Neurosurg Spine 31:660–669, 2019

Cervical disc arthroplasty (CDA) is an accepted motion-sparing technique associated with favorable patient outcomes. However, heterotopic ossification (HO) and adjacent-segment degeneration are poorly understood adverse events that can be observed after CDA. The purpose of this study was to retrospectively examine 1) the effect of the residual exposed endplate (REE) on HO, and 2) identify risk factors predicting radiographic adjacent-segment disease (rASD) in a consecutive cohort of CDA patients.

METHODS A retrospective cohort study was performed on consecutive adult patients (≥ 18 years) who underwent 1- or 2-level CDA at the University of Calgary between 2002 and 2015 with > 1-year follow-up. REE was calculated by subtracting the anteroposterior (AP) diameter of the arthroplasty device from the native AP endplate diameter measured on lateral radiographs. HO was graded using the McAfee classification (low grade, 0–2; high grade, 3 and 4). Change in AP endplate diameter over time was measured at the index and adjacent levels to indicate progressive rASD.

RESULTS Forty-five patients (58 levels) underwent CDA during the study period. The mean age was 46 years (SD 10 years). Twenty-six patients (58%) were male. The median follow-up was 29 months (IQR 42 months). Thirty-three patients (73%) underwent 1-level CDA. High-grade HO developed at 19 levels (33%). The mean REE was 2.4 mm in the high-grade HO group and 1.6 mm in the low-grade HO group (p = 0.02). On multivariable analysis, patients with REE > 2 mm had a 4.5-times-higher odds of developing high-grade HO (p = 0.02) than patients with REE ≤ 2 mm. No significant relationship was observed between the type of artificial disc and the development of high-grade HO (p = 0.1). RASD was more likely to develop in the lower cervical spine (p = 0.001) and increased with time (p < 0.001). The presence of an artificial disc was highly protective against degenerative changes at the index level of operation (p < 0.001) but did not influence degeneration in the adjacent segments.

CONCLUSIONS In patients undergoing CDA, high-grade HO was predicted by REE. Therefore, maximizing the implant-endplate interface may help to reduce high-grade HO and preserve motion. RASD increases in an obligatory manner following CDA and is highly linked to specific levels (e.g., C6–7) rather than the presence or absence of an adjacent arthroplasty device. The presence of an artificial disc is, however, protective against further degenerative change at the index level of operation.

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Lumbar disc arthroplasty versus anterior lumbar interbody fusion: 5-year outcomes for patients in the Maverick disc investigational device exemption study

J Neurosurg Spine 31:347–356, 2019

Despite evidence of its safety and effectiveness, the use of lumbar disc arthroplasty has been slow to expand due in part to concerns about late complications and the risks of revision surgery associated with early devices. More recently, FDA approval of newer devices and improving reimbursements have reversed this trend in the United States. Additional long-term data on lumbar disc arthroplasty are still needed. This study reports the 5-year results of the FDA investigational device exemption clinical trial of the Medtronic Spinal and Biologics’ Maverick total disc replacement.

METHODS Patients with single-level degenerative disc disease from L4 to S1 were randomized 2:1 at 31 investigational sites. In the period from April 2003 to August 2004, 405 patients received the investigational device and 172 patients underwent the control procedure of anterior lumbar interbody fusion. Outcome measures included the Oswestry Disability Index (ODI), numeric rating scales (NRSs) for back and leg pain, the SF-36, disc height, interbody motion, heterotopic ossification (investigational device), adverse events (AEs), additional surgeries, and neurological status. Treatment was considered an overall success when all of the following criteria were met: 1) ODI score improvement ≥ 15 points over the preoperative score; 2) maintenance or improvement in neurological status compared with preoperatively; 3) disc height success, that is, no more than a 2-mm reduction in anterior or posterior height; 4) no serious AEs caused by the implant or by the implant and the surgical procedure; and 5) no additional surgery classified as a failure.

RESULTS Compared to that in the control group, improvement in the investigational group was statistically greater according to the ODI and SF-36 Physical Component Summary (PCS) at 1, 2, and 5 years; the NRS for back pain at 1 and 2 years; and the NRS for leg pain at 1 year. The rates of heterotopic ossification increased over time: 1.0% (4/382) at 1 year, 2.6% (9/345) at 2 years, and 5.9% (11/187) at 5 years. Investigational patients had fewer device-related AEs and serious device-related AEs than the control patients at both 2 and 5 years postoperatively. Noninferiority of the composite measure overall success was demonstrated at all follow-up intervals; superiority was demonstrated at 1 and 2 years.

CONCLUSIONS Lumbar disc arthroplasty is a safe and effective treatment for single-level lumbar degenerative disc disease, resulting in improved physical function and reduced pain up to 5 years after surgery.

Clinical trial registration no.: NCT00635843 (clinicaltrials.gov)

 

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Clinical and Radiological Mid-Term Outcomes of Lumbar Single-Level Total Disc Replacement

Spine 2018;43:105–113

Study Design. Prospective single-center case cohort study. Objective. Evaluation of clinical and radiographic outcomes of a consecutive 122-patient cohort with discogenic back pain, at 2- to 10-year follow-up periods, treated by a single surgeon, with CHARITE Artificial Disc (DePuy Spine, Raynham, MA).

Summary of Background Data. Minimum 2-year clinical and radiographic level 1 data for the first lumbar artificial disc, the CHARITE Artificial Disc (DePuy Spine), have recently been published, demonstrating sustained clinical benefit of the device for the treatment of degenerative disc disease.

Methods. Patients were assessed preoperatively using clinical outcome measures, including visual analog scale (VAS) score back and leg, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36), and Roland-Morris Questionnaires (RMDQ), and further assessed postoperatively, 3-, 6-, 12-months, and yearly thereafter.

Results. Average follow-up was 44.9±3.3 months (n=122). The median age at surgery was 43.0±9.0 years. Preoperative diagnosis included degenerative disc disease in 118 (96.7%) and internal disc disruption in 4 (3.3%). Surgery was performed at L5–S1 in 96 (77.9%) patients and at L4–L5 in 27 (22.1%). Statistically significant clinical improvements from baseline were observed on VAS (back and leg), ODI, SF-36 PCS, SF-36 MCS, and RMDQ 3 months onward. Back VAS scores decreased from 78.221.3 preoperatively to 21.927.8 by final follow-up. ODI scores decreased from 51.117.3 to 16.217.9 at last follow-up. The RMDQ scores also decreased from 16.7±4.7 to 4.2±5.8. SF-36 PCS and MCS increased from 25.7±11.0 to 46.4±10.3 for PCS and from 35.5±17.4 to 51.6±10.8 for MCS. Patient satisfaction surveys indicated that 90.56% patients rated their satisfaction with the surgery as ‘‘excellent’’ or ‘‘good’’ at 2 years. Range of motion averaged 8.6±3.5 (median=8.08) at the last follow-up time point.

Conclusion. Outcomes verify the clinical efficacy of total disc replacement for treatment of discogenic back pain with or without radiculopathy. The outcomes instruments demonstrated statistically significant improvements 3 months onward.

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Four-year results of a prospective single-arm study on 200 semi-constrained total cervical disc prostheses

activ-c-xray

J Neurosurg Spine 25:556–565, 2016

Recent studies have described encouraging outcomes after cervical total disc replacement (cTDR), but there are also critical debates regarding the long-term effects of heterotopic ossification (HO) and the prevalence of adjacent-level degeneration. The aim in this paper was to provide 4-year clinical and radiographic outcome results on the activ C disc prosthesis.

Methods A total of 200 subjects underwent single-level activ C (Aesculap AG) implantation between C-3 and C-7 for the treatment of symptomatic degenerative disc disease. Clinical and radiographic assessments were performed preoperatively, intraoperatively, at discharge, and again at 6 weeks, 6 months, 1 year, 2 years, and 4 years. Radiographic evaluations were done by an independent core laboratory using a specific software for quantitative motion analysis.

Results Neck Disability Index (NDI) and visual analog scale (VAS) score for neck and arm pain decreased significantly from baseline to the 4-year follow-up. The mean improvement for NDI was 20, for VAS severity and frequency of neck pain 26.4 and 28, and for VAS severity and frequency of arm pain 30.7 and 35.1, respectively. The neurological situation improved for the majority of patients (86.4%); 76.1% of cases were asymptomatic. Subsequent surgical interventions were reported in 7% of the cases, including device removals in 3%. In 2.5% a subsidence greater than 3 mm was recorded; 1 of these cases also had a migration greater than 3 mm. No device displacement, expulsion, disassembly, loose or fractured device, osteolysis, or facet joint degeneration at the index level was observed. Segmental lordotic alignment changed from -2.4° preoperatively to -6.2° at 4 years, and postoperative height was maintained during the follow-up. Advanced HO (Grade III and IV) was present in 27.1% of the cases; 82.4% showed segmental mobility. A progression of radiographic adjacent-segment degeneration occurred in 28.2%, but only 4.5% required surgical treatment.

Conclusions The activ C is a safe and effective device for cervical disc replacement confirming the encouraging results after cTDR.

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Cost Utility Analysis of the Cervical Artificial Disc vs Fusion for the Treatment of 2-Level Symptomatic Degenerative Disc Disease: 5-Year Follow-up

mobi-c

Neurosurgery 79:135–145, 2016

The cervical total disc replacement (cTDR) was developed to treat cervical degenerative disc disease while preserving motion.

OBJECTIVE: Cost-effectiveness of this intervention was established by looking at 2-year follow-up, and this update reevaluates our analysis over 5 years.

METHODS: Data were derived from a randomized trial of 330 patients. Data from the 12- Item Short Form Health Survey were transformed into utilities by using the SF-6D algorithm. Costs were calculated by extracting diagnosis-related group codes and then applying 2014 Medicare reimbursement rates. A Markov model evaluated qualityadjusted life years (QALYs) for both treatment groups. Univariate and multivariate sensitivity analyses were conducted to test the stability of the model. The model adopted both societal and health system perspectives and applied a 3% annual discount rate.

RESULTS: The cTDR costs $1687 more than anterior cervical discectomy and fusion (ACDF) over 5 years. In contrast, cTDR had $34 377 less productivity loss compared with ACDF. There was a significant difference in the return-to-work rate (81.6% compared with 65.4% for cTDR and ACDF, respectively; P = .029). From a societal perspective, the incremental cost-effective ratio (ICER) for cTDR was 2$165 103 per QALY. From a health system perspective, the ICER for cTDR was $8518 per QALY. In the sensitivity analysis, the ICER for cTDR remained below the US willingness-to-pay threshold of $50 000 per QALY in all scenarios (2$225 816 per QALY to $22 071 per QALY).

CONCLUSION: This study is the first to report the comparative cost-effectiveness of cTDR vs ACDF for 2-level degenerative disc disease at 5 years. The authors conclude that, because of the negative ICER, cTDR is the dominant modality.

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ALIF and total disc replacement versus 2-level circumferential fusion with TLIF: a prospective, randomized, clinical and radiological trial

ALIF-TDR vs TLIF

Eur Spine J (2016) 25:1558–1566

Study design: Prospective, randomized trial.

Purpose: The treatment of degenerative disc disease (DDD) with two-level fusion has been associated with a reasonable rate of complications. The aim of the present study was to compare (Hybrid) stand-alone anterior lumbar interbody fusion (ALIF) at L5/S1 with total disc replacement at L4/5 (TDR) as an alternative surgical strategy to (Fusion) 2-level circumferential fusion employing trans- foraminal lumbar interbody fusion (TLIF) with transpedicular stabilization at L4–S1.

Methods: A total of 62 patients with symptomatic DDD of segments L5/S1 (Modic ≥2°) and L4/5 (Modic ≤2°; positive discography) were enrolled; 31 were treated with Hybrid and 31 with Fusion. Preoperatively, at 0, 12, and a mean follow-up of 37 months, clinical (ODI, VAS) and radiological evaluations (plain/extension-flexion radiographs evaluated for implant failure, fusion, global and segmental lordosis, and ROM) were performed.

Results: In 26 of 31 Hybrid and 24 of 31 Fusion patients available at the final follow-up, we found a significant clinical improvement compared to preoperatively. Hybrid patients had significantly lower VAS scores immediately postoperatively and at follow-up compared to Fusion patients. The complication rates were low and similar between the groups. Lumbar lordosis increased in both groups. The increase was mainly located at L4–S1 in the Hybrid group and at L1–L4 in the Fusion group. Hybrid patients presented with increased ROM at L4/5 and L3/4, and Fusion patients presented with increased ROM at L3/4, with significantly greater ROM at L3/4 compared to Hybrid patients at follow-up.

Conclusions Hybrid surgery is a viable surgical alternative for the presented indication. Approach-related inferior trauma and the balanced restoration of lumbar lordosis resulted in superior clinical outcomes compared to two-level circumferential fusion with TLIF.

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Lumbar Total Disc Replacement for Discogenic Low Back Pain

Lumbar Total Disc Replacement for Discogenic Low Back Pain

Spine 2015;40:1873–1881

A prospective, multicenter, randomized, controlled, investigational device exemption (IDE) noninferiority trial.

Objective. The aim of this study was to evaluate the comparative safety and effectiveness of lumbar total disc replacement (TDR) in the treatment of patients with symptomatic degenerative disc disease (DDD) who are unresponsive to nonsurgical therapy.

Summary of Background Data. Lumbar TDR has been used to alleviate discogenic pain and dysfunction while preserving segmental range of motion and restoring stability. There is a paucity of data available regarding the comparative performance of lumbar TDR.

Methods. Patients presenting with symptomatic single-level lumbar DDD who failed at least 6 months of nonsurgical management were randomly allocated (2:1) to treatment with an investigational TDR device (activL1, n=218) or FDA-approved control TDR devices (ProDisc-L or Charité, n=106). The hypothesis of this study was that a composite effectiveness outcome at 2 years in patients treated with activL would be noninferior (15% delta) to that in controls.

Results. The primary composite endpoint of this study was met, which demonstrated that the activL TDR was noninferior to control TDR (P<0.001). A protocol-defined analysis of the primary composite endpoint also confirmed that activL was superior to controls (P=0.02). Radiographic success was higher with activL versus controls (59% vs. 43%; P<0.01). Mean back pain severity improved by 74% with activL and 68% with controls. Oswestry Disability Index scores decreased by 67% and 61% with activL and controls, respectively. Patient satisfaction with treatment was over 90% in both groups at 2 years. Return to work was approximately 1 month shorter (P=0.08) with activL versus controls. The rate of device-related serious adverse events was lower in patients treated with activL versus controls (12% vs. 19%; P=0.13). Surgical reintervention rates at the index level were comparable (activL 2.3%, control 1.9%).

Conclusion. The single-level activL TDR is safe and effective for the treatment of symptomatic lumbar DDD through 2 years.

Level of Evidence: 2

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Analysis of in vivo kinematics of 3 different cervical devices: Bryan disc, ProDisc-C, and Prestige LP disc

J Neurosurg Spine 15:630–635, 2011.DOI: 10.3171/2011.8.SPINE11273

Cervical arthroplasty has emerged as a means of preventing adjacent segment disease by preserving motion, restoring sagittal balance, and mimicking natural spinal kinematics. The purpose of this retrospective in vivo study was to characterize the impact of arthroplasty on sagittal balance and segmental kinematics of the cervical spine.

Methods. Sixty patients receiving the Bryan disc, ProDisc-C, or Prestige LP disc were retrospectively analyzed. Only single-level arthroplasty cases were included in this study. Lateral dynamic radiographs of the cervical spine were evaluated using quantitative measurement analysis software to determine the kinematics at the index level both preoperatively and 1 year postoperatively. Collected parameters included range of motion (ROM), disc angles, shell angles, anterior and posterior disc heights (ADHs/PDHs), translation, and center of rotation (COR). Preoperative and postoperative data were compared using the Student t-test, with p < 0.05 indicating significance.

Results. The Bryan and Prestige LP discs preserved motion, whereas the ProDisc-C increased segmental ROM from extension to flexion. Following surgery, the Bryan disc exhibited significant shell angle kyphosis, while Pro- Disc-C and Prestige LP retained lordosis. Both ADHs and PDHs decreased following insertion of the Bryan disc. In contrast, the ProDisc-C increased the ADHs and PDHs by 80% and 52%, respectively, and the Prestige LP disc increased the ADHs and PDHs by 20%. Only the ProDisc-C demonstrated significant translation of 0.7 mm. The ProDisc-C shifted the COR x by 0.9 mm anteriorly, while the Prestige LP disc demonstrated a significant superior shift of 2.2 mm in COR y.

Conclusions. All discs adequately maintained ROM at the surgical level. The greatest difference among the 3 devices was in the disc height and index angle measurements

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Cervical Facet Degeneration After Total Disc Replacement: 280 Levels in 162 Patients: 5-Year Follow-up

Neurosurg Q 2011;21:17–21.

Much information and classifications of lumbar facet joint degeneration after lumbar total disc replacement are available, but nowadays in the cervical spine this concept is unstudied.

Analyzing our experience, we propose a computed tomography (CT) scan classification to evaluate degenerative facet joint disease after cervical arthroplasty. After 5-year follow-up for total disc replacement in a consecutive series of 162 patients (44.5±8.6-y-old) with a total of 280 Porous Coated Motion total cervical disc replacement from C3-4 to C7-T1, we analyzed the facet degeneration in 4 grades using CT scan, and compared with preoperative images. CT scans, x-rays, and clinical outcomes were collected preoperatively and postoperatively after 3 and 6 months, and annually after 12-month follow-up. The Neck Disability Index and Visual Analog Scale were used to assess pain and functional outcomes.

From all operated levels, we found 8.57% (24 levels) of degenerated facets. On the basis of the proposed classification, 50% (12 levels) of all degenerated levels had grade I, 37.5% (9 levels) with grade II, 8.3% (2 levels) with grade III, and 4.16% (1 level) had grade IV of facet degeneration. In patients with grades III and IV, it was possible to observe a worsening in Visual Analog Scale outcome assessment.

Facet joint degeneration is a possible consequence of cervical disc arthroplasty, despite its low rate occurrence. We did not find relationship between the early grades of CT observed facet degeneration and clinical results, but in grades III and IV there was correlation. A CT scan classification to evaluate cervical degenerative facet joint disease is essential to better understand and report this spinal phenomenon.

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Lumbar total disc replacement from an extreme lateral approach: clinical experience with a minimum of 2 years’ follow-up

J Neurosurg Spine 14:38–45, 2011. (DOI: 10.3171/2010.9.SPINE09865)

Current lumbar total disc replacement (TDR) devices require an anterior approach for implantation. This approach has inherent limitations, including risks to abdominal structures and the need for resection of the anterior longitudinal ligament (ALL). Placement of a TDR device from a true lateral (extreme lateral interbody fusion [XLIF]) approach is thought to offer a less invasive option to access the disc space, preserving the stabilizing ligaments and avoiding scarring of anterior vasculature. In this study, the authors attempted to quantify the clinical and radiographic outcomes of a lateral approach to lumbar TDR from a prospective, single-center experience.

Methods. A TDR device designed for implantation through a true lateral, retroperitoneal, transpsoas approach (XLIF) was implanted in 36 patients with discography-confirmed 1- or 2-level degenerative disc disease. Clinical (pain and function) and radiographic (range of motion [ROM]) data were prospectively collected preoperatively, postoperatively, and serially for a minimum of 24 months’ follow-up.

Results. Thirty-six surgeries were performed in 16 men and 20 women (mean age 42.6 years). Surgeries included 15 single-level TDR procedures at L3–4 or L4–5, three 2-level TDR procedures spanning L3–4 and L4–5, and 18 hybrid procedures (anterior lumbar interbody fusion [ALIF]) at L5–S1 and TDR at L4–5 [17] or L3–4 [1]). Operative time averaged 130 minutes, with an average blood loss of 60 ml and no intraoperative complications. Postoperative radiographs showed good device placement. All patients were walking within 12 hours of surgery and all but 9 were discharged the next day (7 of 9 had hybrid TDR/ALIF procedures). Five patients (13.8%) had psoas weakness and 3 (8.3%) had anterior thigh numbness postoperatively, both resolving within 2 weeks. One patient (2.8%) demonstrated weakness of the leg ipsilateral to the approach side, which lasted through the 3-month visit but was resolved by the 6-month visit. One patient (2.8%) was found to have hypertrophy of the quadriceps contralateral to the approach side at the 12-month visit, which was resolved by the 2-year visit. Four patients (11%) had postoperative facet joint pain, all in hybrid cases. All patients were 2 years or more postsurgery as of this writing, although 3 were lost to follow-up between the 1- and 2-year visits. In 2 cases (5.6%), removal of the TDR device and revision to fusion were required due to unresolved pain. At 2 years’ follow-up, the average visual analog scale and Oswestry Disability Index scores had improved 69.6% and 61.4%, respectively, and ROM averaged 8.6°, well within physiological norms.

Conclusions. Long-term results of a laterally placed TDR device demonstrate maintenance of pain relief and functional improvement. The benefits of this technique—minimal morbidity, avoiding mobilization of the great vessels, preserving the ALL, biomechanically stable orientation, and broader revision options—suggest a promising new direction for TDR procedures.

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Facet Joint Biomechanics at the Treated and Adjacent Levels After Total Disc Replacement

SPINE Volume 36, Number 1, pp E27–E32

Study Design. Biomechanical study using human cadaveric lumbar spines.

Objective. To evaluate effects of total disc replacement (TDR) on spine biomechanics at the treated and adjacent levels.

Summary of Background Data. Previous studies on spine biomechanics after TDR were focused on facet forces and range of motion and report contradictory results. Characterization of contact pressure, peak contact pressure, force, and peak force before and after TDR may lead to a better understanding of facet joint function and may aid in prediction of long-term outcomes after TDR.

Methods. Seven fresh-frozen human cadaveric lumbar spines were potted at T12 and L5 and installed in a 6 degrees of freedom displacement- controlled testing system. Displacements of 15° flexion/ extension, 10° right/left bending, and 10° right/left axial rotation were applied. Contact pressure, peak contact pressure, force, peak force, and contact area for each facet joint were recorded at L2–L3 and L3–L4 both before and after TDR at L3–L4. The data were analyzed with analysis of variance and t tests.

Results. Axial rotation had the most impact on contact pressure, peak contact pressure, force, peak force, and contact area in intact spines. During lateral bending and axial rotation, TDR resulted in a significant increase in facet forces at the level of treatment and a decrease in contact pressure, peak contact pressure, and peak force at the level superior to the TDR. With flexion/extension, there was a decrease in peak contact pressure and peak contact force at the superior level.

Conclusion. Our study demonstrates that rotation is the most demanding motion for the spine. We also found an increase in facet forces at the treated level after TDR. We are the first to show a decrease in several biomechanical parameters after TDR at the adjacent superior level. In general, our findings suggest there is an increase in loading of the facet joints at the level of disc implantation and an overall unloading effect at the level above.

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Overview of disc arthroplasty—past, present and future

DOI:10.1007/s00701-009-0529-5. Acta Neurochirugica

Degenerative disc disease is one of the most frequent spinal disorders. The anatomy and the biomechanics of the intervertebral disc are very complex, and the pathomechanics of its degeneration are poorly understood. Despite this complexity and uncertainty, great advances have been made in the field of disc replacement technology, with promising results. Difficulties are continuously being encountered, but careful analysis of the results and intensive research and development will assist in countering these problems. There are approximately 40 clinical reports in the literature describing various aspects of randomised controlled trials involving intervertebral disc arthroplasty. However, the majority of these publications do not provide reliable information, in that they give only interim results and/or the results from just one of the many centres in multicentre studies. Such publications must be interpreted with caution, since they do not always represent the results of the whole study population and may hence be underpowered. We identified six randomised controlled trials that compared the final clinical outcomes of disc arthroplasty and spinal fusion. The present systematic review attempts to give an overview of the current status of disc arthroplasty.

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Overview of disc arthroplasty—past, present and future

Acta Neurochir (2010) 152:393–404. DOI 10.1007/s00701-009-0529-5

Degenerative disc disease is one of the most frequent spinal disorders. The anatomy and the biomechanics of the intervertebral disc are very complex, and the pathomechanics of its degeneration are poorly understood. Despite this complexity and uncertainty, great advances have been made in the field of disc replacement technology, with promising results. Difficulties are continuously being encountered, but careful analysis of the results and intensive research and development will assist in countering these problems. There are approximately 40 clinical reports in the literature describing various aspects of randomised controlled trials involving intervertebral disc arthroplasty. However, the majority of these publications do not provide reliable information, in that they give only interim results and/or the results from just one of the many centres in multicentre studies. Such publications must be interpreted with caution, since they do not always represent the results of the whole study population and may hence be underpowered. We identified six randomised controlled trials that compared the final clinical outcomes of disc arthroplasty and spinal fusion. The present systematic review attempts to give an overview of the current status of disc arthroplasty.

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