Final Long-Term Reporting from a Randomized Controlled IDE Trial for Lumbar Artificial Discs in Single-Level Degenerative Disc Disease: 7-Year Results

Lumbar Total Disc Replacements for Degenerative Disc Disease: A Systematic Review of Outcomes With a Minimum of 5 years Follow-Up

STUDY DESIGN

Systematic Review.

OBJECTIVES

To systematically review the clinical outcomes, re-operation, and complication rates of lumbar TDR devices at mid-to long-term follow-up studies for the treatment of lumbar degenerative disc disease (DDD).

METHODS

A systematic search was conducted on PubMed, SCOPUS, and Google Scholar to identify follow-up studies that evaluated clinical outcomes of lumbar TDR in patients with DDD. The included studies met the following criteria: prospective or retrospective studies published from 2012 to 2022; a minimum of 5 years post-operative follow-up; a study sample size >10 patients; patients >18 years of age; containing clinical outcomes with Oswestry Disability Index (ODI), Visual Analog Scale (VAS), complication or reoperation rates.

RESULTS

Twenty-two studies were included with data on 2284 patients. The mean follow-up time was 8.30 years, with a mean follow-up rate of 86.91%. The study population was 54.97% female, with a mean age of 42.34 years. The mean VAS and ODI pain score improvements were 50.71 ± 6.91 and 30.39 ± 5.32 respectively. The mean clinical success and patient satisfaction rates were 74.79% ± 7.55% and 86.34% ± 5.64%, respectively. The mean complication and reoperation rates were 18.53% ± 6.33% and 13.6% ± 3.83%, respectively. There was no significant difference when comparing mid-term and long-term follow-up studies for all clinical outcomes.

CONCLUSIONS

There were significant improvements in pain reduction at last follow-up in patients with TDRs. Mid-term follow-up data on clinical outcomes, complication and reoperation rates of lumbar TDRs were maintained longer term.

Preservation of Motion in Spine Surgery

The number of spinal procedures and spinal fusions continues to grow. Although fusion procedures have a high success rate, they have inherent risks such as pseudarthrosis and adjacent segment disease. New innovations in spine techniques have sought to eliminate these complications by preserving motion in the spinal column. Several techniques and devices have been developed in the cervical and lumbar spine including cervical laminoplasty, cervical disk ADA, posterior lumbar motion preservation devices, and lumbar disk ADA. In this review, advantages and disadvantages of each technique will be discussed.

Lumbar arthroplasty for treatment of primary or recurrent lumbar disc herniation

PURPOSE

Microdiscectomy is the current gold standard surgical treatment for primary lumbar disc herniations that fail non-surgical measures. Herniated nucleus pulposus is the manifestation of underlying discopathy that remains unaddressed with microdiscectomy. Therefore, risk remains of recurrent disc herniation, progression of the degenerative cascade, and on-going discogenic pain. Lumbar arthroplasty allows for complete discectomy, complete direct and indirect decompression of neural elements, restoration of alignment, restoration of foraminal height, and preservation of motion. In addition, arthroplasty avoids disruption of posterior elements and musculoligamentous stabilizers. The purpose of this study is to describe the feasibility of the use of lumbar arthroplasty in the treatment of patients with primary or recurrent disc herniations. In addition, we describe the clinical and peri-operative outcomes associated with this technique.

METHODS

All patients that underwent lumbar arthroplasty by a single surgeon at a single institution from 2015 to 2020 were reviewed. All patients with radiculopathy and pre-operative imaging demonstrating disc herniation that received lumbar arthroplasty were included in the study. In general, these patients were those with large disc herniations, advanced degenerative disc disease, and a clinical component of axial back pain. Patient-reported outcomes of VAS back, VAS leg, and ODI pre-operatively, at three months, one year, and at last follow-up were collected. Reoperation rate, patient satisfaction, and return to work were documented at last follow-up.

RESULTS

Twenty-four patients underwent lumbar arthroplasty during the study period. Twenty-two (91.6%) patients underwent lumbar total disc replacement (LTDR) for a primary disc herniation. Two patients (8.3%) underwent LTDR for a recurrent disc herniation after prior microdiscectomy. The mean age was 40 years. The mean pre-operative VAS leg and back pain were 9.2 and 8.9, respectively. The mean pre-operative ODI was 22.3. Mean VAS back and leg pain was 1.2 and 0.5 at three months post-operative. The mean VAS back and leg pain was 1.3 and 0.6 at one year post-operative. The mean ODI was 3.0 at one year post-operative. One patient (4.2%) underwent re-operation for migrated arthroplasty device which required repositioning. At last follow-up, 92% of patients were satisfied with their outcome and would undergo the same treatment again. The mean time for return-to-work was 4.8 weeks. After returning to work, 89% of patients required no further leave of absence for recurrent back or leg pain at last follow-up. Forty-four percent of patients were pain free at last follow-up.

CONCLUSION

Most patients with lumbar disc herniations can avoid surgical intervention altogether. Of those that require surgical treatment, microdiscectomy may be appropriate for certain patients with preserved disc height and extruded fragments. In a subset of patients with lumbar disc herniation that require surgical treatment, lumbar total disc replacement is an effective option by performing complete discectomy, restoring disc height, restoring alignment, and preserving motion. The restoration of physiologic alignment and motion may result in durable outcomes for these patients. Longer follow-up and comparative and prospective trials are needed to determine how the outcomes of microdiscectomy may differ from lumbar total disc replacement in the treatment of primary or recurrent disc herniation.

Usefulness of Detecting Brain-Derived Neurotrophic Factor in Intervertebral Disc Degeneration of the Lumbosacral Spine

BACKGROUND In determining the etiology of pain of discogenic origin, attention is paid to the role of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF). Considering the potential role of BDNF in the etiology of pain during intervertebral disc degeneration (IVDD), this study aimed to assess changes in the number of BDNF-positive nerve fibers and levels of BDNF in IVDD of the lumbosacral spine in comparison to intervertebral discs (IVDs) of the control group (cadavers). MATERIAL AND METHODS The study group comprised 113 patients with IVDD of the lumbosacral spine. The control group consisted of 81 people (cadavers). We performed hematoxylin-eosin staining to assess IVD structures (degeneration), immunohistochemistry to determine the number of BDNF-positive nerve fibers, and an enzyme-linked immunosorbent assay and western blot to quantify BDNF levels in IVDs. RESULTS Levels of BDNF in the study group were significantly higher than in the control group (17.91±19.58 pg/mg; P<0.05). Furthermore, BDNF levels were significantly higher in the annulus fibrosus compared to the nucleus pulposus of the intervertebral disc (5.50±6.40 pg/mg; P<0.05). Neither the number of BDNF-positive nerves (P=0.359) nor BDNF concentration (P=0.706) were significantly correlated with the degree of perceived pain. The number of BDNF-positive fibers per 1 mm2 was not found to differ significantly according to the radiological degree of degeneration of the lumbosacral spine based on the Pfirrmann scale (P=0.735). CONCLUSIONS The level of BDNF expression may be indicative of IVD degeneration, although it does not predict the degree of this degeneration.

Long-term outcomes following lumbar total disc replacement with M6-L

Background

The motion preserving benefits of lumbar total disc replacement (LTDR) are well established. There is a paucity of long-term follow-up data on the M6-L prosthesis. The aim was to evaluate the clinical and radiographic outcomes of patients undergoing LTDR with M6-L and make comment about its effectiveness and durability.

Methods

A retrospective single center chart review was performed of all patients who underwent LTDR with M6-L between January 1, 2011, and January 1, 2021, either as standalone device or combined with a caudal anterior lumbar interbody fusion (ALIF) (hybrid procedure). Preoperative, postoperative, and final follow-up patient reported outcome measures (PROMs) (VAS back, VAS leg, ODI, and SF-12) and patient satisfaction were recorded prospectively. Device range of motion (ROM), adjacent segment degeneration/disease and heterotopic ossification (HO) were obtained from flexion and extension lumbar radiographs at most recent follow-up.

Results

Sixty patients underwent LTDR with the M6-L device. Mean age was 41 [16-71] years and 38 (63%) were male. Sixteen (26.7%) underwent standalone LTDR, 42 (70.0%) a hybrid procedure, and 2 (3.3%) a 3-level procedure. Twenty-three (38.3%) patients were lost to follow-up. Thirty-seven (61.7%) were followed for a mean of 4.3 [1-10] years with 36/37 reviewed at a minimum of 2-years and 13/37 followed for over 5-years. Only one patient with osteopenia needed index level revision LTDR surgery for subsidence requiring supplemental posterior instrumentation. There were no osteolysis induced device related failures. Thirty patients obtained long-term follow-up radiographic data. Six patients had adjacent segment degeneration; none required surgery for adjacent segment disease (ASD). Three patients presented with clinically significant HO (2 with McAfee class III, 1 with class IV). The average M6-L ROM was 8.6 degrees. Mean preoperative baseline PROMs demonstrated statistically significant improvements postoperatively and were sustained at last follow-up (P<0.05).

Conclusions

Total disc replacement (TDR) with M6-L showed clinically significant improvement in PROMs that were sustained at long-term follow-up. There were no osteolysis induced device related failures. The device ROM was maintained and showed a downward trend over the 10-year study follow-up period. This paper demonstrated that the M6-L was an effective and durable arthroplasty device in this series.

Predictors of long-term clinical outcomes in adult patients after lumbar total disc replacement: development and validation of a prediction model

OBJECTIVE

Long-term outcomes of single-level lumbar arthroplasty are understood to be very good, with the most recent Investigational Device Exemption (IDE) trial showing a < 5% reoperation rate at the close of the 7-year study. This post hoc analysis was conducted to determine whether specific patients from the activL IDE data set had better outcomes than the mean good outcome of the IDE trial, as well as to identify contributing factors that could be optimized in real-world use.

METHODS

Univariable and multivariable logistic regression models were developed using the randomized patient set (n = 283) from the activL trial and used to identify predictive factors and to derive risk equations. The models were internally validated using the randomized patient set and externally validated using the nonrandomized patient set (n = 52) from the activL trial. Predictive power was assessed using area under the receiver operating characteristic curve analysis.

RESULTS

Two factors were significantly associated with achievement of better than the mean outcomes at 7 years. Randomization to receive the activL device was positively associated with better than the mean visual analog scale (VAS)-back pain and Oswestry Disability Index (ODI) scores, whereas preoperative narcotics use was negatively associated with better than the mean ODI score. Preoperative narcotics use was also negatively associated with return to unrestricted full-time work. Other preoperative factors associated with positive outcomes included unrestricted full-time work, working manual labor after index back injury, and decreasing disc height. Older age, greater VAS-leg pain score, greater ODI score, female sex, and working manual labor before back injury were identified as preoperative factors associated with negative outcomes. Preoperative BMI, VAS-back pain score, back pain duration ≥ 1 year, SF-36 physical component summary score, and recreational activity had no effect on outcomes.

CONCLUSIONS

Lumbar total disc replacement for symptomatic single-level lumbar degenerative disc disease is a well-established option for improving long-term patient outcomes. Discontinuing narcotics use may further improve patient outcomes, as this analysis identified associations between no preoperative narcotics use and better ODI score relative to the mean score of the activL trial at 7 years and increased likelihood of return to work within 7 years. Other preoperative factors that may further improve outcomes included unrestricted full-time work, working manual labor despite back injury, sedentary work status before back injury, and randomization to receive the activL device. Tailoring patient care before total disc replacement may further improve patient outcomes.