Lumbar Total Disk Replacement Device Removals and Revisions Performed During a 20-Year Experience with 2141 Patients

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.

Impact of Age on the Occurrence of Vascular Complications in Patients Undergoing Anterior Lumbar Approach Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate the impact of age on incidence of vascular complications in patients undergoing anterior lumbar approach surgery.

SUMMARY OF BACKGROUND DATA

Anterior approach lumbar spinal surgery may facilitate use of intervertebral devices with larger endplate coverage and increased lordosis. Despite the advantages of this approach, risks related to vascular injury in older patients have been described in the literature.

METHODS

In total, 751 consecutive patients with degenerative spinal pathology who underwent stand-alone anterior lumbar interbody fusion (ALIF), ALIF combined with posterior fusion and/or instrumentation (360), total disc replacement (TDR), or hybrid procedures (ALIF and TDR) were included. Data collected included general patient descriptive data, surgery details, intraoperative vascular injury, and post-operative vascular complications (deep vein thrombosis (DVT) and/or pulmonary embolism (PE)). Rates of vascular complications were compared across age groups. Additionally, the mean age of patients was compared between those with vs. without vascular complications.

RESULTS

Overall mean age was 50.4 years (range 20-83 years). Mean estimated blood loss was 91.3 ml (range 10 to 2800 ml). A total of 15 patients, 2.0%, had vascular complications. There were 10 cases (1.3%) of intraoperative injury to iliac arteries or iliolumbar veins (mean blood loss was 721 mL and all were repaired intraoperatively). Postoperatively, 6 patients (0.8%) developed DVT and/or PE (one patient had both). With respect to age, there were no significant differences in rates of intra-operative, post-operative, or combined vascular complication rates across the age group (P>0.38). Additionally, there were no statistically significant differences in the mean ages of patients with vs. those without vascular complications (P>0.17).

CONCLUSION

Overall incidence of vascular complications was 2.0%. No relationship between vascular complications and age was demonstrated. These data suggest that increased age may not necessarily be an absolute contraindication for anterior lumbar approach surgery.

Is the Use of Intraoperative Neuromonitoring Justified During Lumbar Anterior Approach Surgery?

BACKGROUND

Intraoperative neuromonitoring (IONM) became widely used in spine surgery to reduce the risk of iatrogenic nerve injury. However, the proliferation of IONM has fallen into question based on effectiveness and costs, with a lack of evidence supporting its benefit for specific spine surgery procedures. The purpose of this study was to evaluate the use of IONM and the rate of neurological injury associated with anterior lumbar spinal surgery.

METHODS

This was a retrospective study on a consecutive series of 359 patients undergoing lumbar anterior approach surgery for anterior lumbar interbody fusion (ALIF), total disc replacement (TDR), or hybrid (ALIF with TDR) for the treatment of symptomatic disc degeneration. Patients undergoing any posterior spine surgery were excluded. Operative notes were reviewed to identify any changes in IONM and the surgeon's response. Clinic notes were reviewed up to 3 months postoperatively for indications of iatrogenic nerve injury.

RESULTS

There were 3 aberrant results with respect to IONM. Changes in IONM of a lower extremity occurred for 1 patient (0.3%). The surgeon evaluated the situation and there was no observable reason for the IONM change. Upon waking, the patient was found to have no neurological deficit. There were 2 cases of neurologic deficits in this population, which were classified as false-negatives of IONM (0.56%, 95% CI: 0.1% to 1.8%). In both cases, the patients were found to have a foot drop after the anterior approach surgery.

CONCLUSION

In this study, there was 1 false-positive and 2 false-negative results of IONM. These data suggest that IONM is not beneficial in this population. However, many surgeons may feel obligated to use IONM for medicolegal reasons. There is a need for future studies to delineate cases in which IONM is beneficial and the type of monitoring to use, if any, for specific spine surgery types.

CLINICAL RELEVANCE

This study questions the routine use of IONM in anterior lumbar approach surgery for the treatment of symptomatic disc degeneration. This has significant implications related to the cost of this practice.

LEVEL OF EVIDENCE: 4

Evaluating alternatives to dual-energy x-ray absorptiometry for assessing bone quality in patients undergoing spine surgery

OBJECTIVE

The purpose of this study was to compare and contrast lumbar bone quality and osteoporosis/osteopenia screening results via dual-energy x-ray absorptiometry (DEXA), CT, and MRI.

METHODS

A consecutive series of 426 candidates screened for lumbar disc replacement over a 5-year period beginning in 2018 was reviewed. Patients with a preoperative lumbar spine DEXA scan and a CT and/or MRI scan were included. The primary outcome measures included the bone mineral density (BMD) and osteoporosis or osteopenia classification from DEXA scans, Hounsfield units (HUs) for CT, and vertebral bone quality (VBQ) assessment for MRI. Patients were included if they had a DEXA scan within 1 year of an MRI or CT scan. DEXA BMD scores from composite or level-by-level reports were recorded. Asynchronous MRI and CT measurements were conducted using PACS. Interrater and intrarater reliability scores were generated for both CT and MRI measurements and ranged from 1.000 for MRI L1-4 scans to 0.683 for MRI VBQ.

RESULTS

All 3 types of scans were statistically significantly correlated with one another; however, CT was more strongly correlated with the lumbar DEXA value (r = 0.439, p < 0.001). The correlation between MRI VBQ and DEXA was -0.103, (p < 0.045). The CT level-by-level measurements correlate with the corresponding level-by-level DEXA BMD values (correlation ranging from 0.531 to 0.289, p < 0.001 to p = 0.007). CT HU values were more strongly related to osteoporosis/osteopenia classification based on DEXA T-scores than were MRI VBQ values. Receiver operating characteristic analyses found that the area under the curve was 0.817 for CT and 0.539 for MRI.

CONCLUSIONS

These results demonstrate that CT HUs more closely correlate to DEXA scores than MRI VBQ in this population of patients undergoing surgery for symptomatic disc degeneration. Thus, CT may be an alternative to DEXA for assessing VBQ in this population.

Assessing lumbar vertebral bone quality: a methodological evaluation of CT and MRI as alternatives to traditional DEXA

PURPOSE

The purpose of this study was to investigate the impact of various methods on the assessment of vertebral bone quality.

METHODS

A consecutive series of 427 candidates for lumbar disc replacement with lumbar DEXA and MRI and/or CT scans were included. Two measurement techniques were used on CTs-a sagittal and axial. From axial images, the upper, mid, and lower portions of each vertebral body were measured. Four MRI vertebral bone quality (VBQ) calculations were generated using separate equations.

RESULTS

All CT measures were highly correlated with each other, regardless of measurement or calculation method (range 0.925-0.995). Sagittal measurements were highly correlated with axial (r = 0.928, p < 0.001). CT values were correlated with DEXA (range 0.446-0.534). There was no benefit to measuring multiple axial images of each vertebral body vs. just midbody (r = 0.441 and 0.455, respectively). No MRI VBQ values were highly correlated with DEXA (r =  -  0.103, p = 0.045). In receiver operating curve analysis, the area under the curve ranged from 0.539 to 0.558, indicating poor ability of VBQ to identify osteoporosis/osteopenia.

CONCLUSION

CT produced values more closely related to DEXA, while MRI was less reliable for osteoporosis/osteopenia screening. On CT, there was no benefit to making multiple measurements for each vertebral body to calculate a composite. Measuring sagittal CT images produced values similar to axial and required less time. While assessing bone quality from existing images rather than getting an additional DEXA scan is appealing, the methods of measuring these images needs standardization to maximize their utility.

Interspinous-Interbody Fusion via a Strictly Lateral Surgical Approach: A Biomechanical Stabilization Comparison to Constructs Requiring Both Lateral and Posterior Approaches

Objective Lumbar fusion performed through lateral approaches is becoming more common. The interbody devices are generally supported by supplemental posterior fixation implanted through a posterior approach, potentially requiring a second incision and intraoperative repositioning of the patient. A minimally invasive lateral interspinous fixation device may eliminate the need for intraoperative repositioning and avoid disruption of the supraspinous ligament. The objective of this in vitrobiomechanical study was to investigate segmental multidirectional stability and maintenance of foraminal distraction of a lateral interspinous fixation device compared to commonly used pedicle screw and facet screw posterior fixation constructs when combined with lumbar interbody cages. Methods Six human cadaver lumbar spine specimens were subjected to nondestructive quasistatic loading in the following states: (1) intact; (2) interspinous fixation device alone and (3) with lateral interbody cage; (4) lateral lumbar interbody cage with bilateral pedicle screws; (5) lateral lumbar interbody cage with unilateral pedicle screws; and (6) lateral lumbar interbody cage with facet screws. Multidirectional pure bending in 1.5 Nm increments to 7.5 Nm, and 7.5 Nm flexion-extension bending with a 700 N compressive follower load were performed separately with optoelectronic segmental motion measurement. Relative angular motions of L2-L3, L3-L4, and L4-L5 functional spinal units were evaluated, and the mean instantaneous axis of rotation in the sagittal plane was calculated for the index level. Foraminal height was assessed during combined flexion-extension and compression loading for each test construct. Results All implant configurations significantly restricted flexion-extension motion compared with intact (p < 0.05). No significant differences were found in flexion-extension when comparing the different posterior implants combined with lateral lumbar interbody cages. All posterior fixation devices provided comparable neuroforaminal distraction and maintained distraction during flexion and extension. Conclusions When combinedwith lateral lumbar interbody cages, the minimally invasive lateral interspinous fixation device effectively stabilized the spine and maintained neuroforaminal distraction comparable to pedicle screw constructs or facet screws. These results suggest the lateral interspinous fixation device may provide a favorable alternative to other posterior systems that require patient repositioning during surgery and involve a greater disruption of native tissues.

Impact of previous lumbar spine surgery on the outcome of lumbar total disc replacement: analysis of prospective 5-year follow-up study data

PURPOSE

It is sometimes anticipated that patients with prior spine surgery will have a compromised outcome from future procedures. The purpose of this study was to compare TDR outcomes in patients with prior lumbar spine surgery to those with no previous surgery.

METHODS

Post hoc analysis was performed on 5-year follow-up data collected prospectively in the multi-centre FDA-regulated trial for the activL® Artificial Disc which involved 376 patients treated for single-level symptomatic disc degeneration. Clinical outcome measures included the Oswestry Disability Index (ODI), visual analog scales (VAS) assessing back and leg pain, SF-36, adverse events, and re-operations. Radiographic outcomes included flexion/extension range of motion (ROM) and translation of the operated segment. Patients were divided into two groups: Prior Lumbar Surgery (PLS, n = 92) and No Prior Lumbar Surgery (NPLS, n = 284).

RESULTS

Baseline demographics were similar in the two groups. ODI, VAS, and SF-36 Physical Component Scale scores improved significantly (p < 0.05) from baseline in both groups with improvements maintained through 5-year post-TDR with no significant differences between groups. There were no statistically significant differences in rates of serious device-related events, procedure-related events, or re-operations. While ROM was significantly less prior to TDR surgery in the PLS group, there was no significant difference in ROM at post-operative points.

CONCLUSION

Prior lumbar spine surgery was not associated with compromised outcomes following TDR. These results are in line with reports from earlier studies with shorter follow-up, finding that non-destabilizing prior surgery is not a contra-indication for TDR provided that selection criteria are met.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Evaluation of Anterior Lumbar Interbody Fusion Performed Using a Stand-Alone, Integrated Fusion Cage

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.

LEVEL OF EVIDENCE: 4

In which cases do surgeons specializing in total disc replacement perform fusion in patients with symptomatic lumbar disc degeneration?

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.

Prospective, multicenter study of 2-level cervical arthroplasty with a PEEK-on-ceramic artificial disc

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of a PEEK-on-ceramic cervical total disc replacement (cTDR) device for the treatment of 2-level cervical disc disease with radiculopathy and/or myelopathy.

METHODS

The study was a prospective, nonrandomized, historically controlled FDA investigational device exemption trial evaluating the Simplify Cervical Artificial Disc for use at 2 levels. The anterior cervical discectomy and fusion (ACDF) control group was derived from a propensity score-matched (using subclassification) cohort of patients who participated in an earlier prospective trial in which similar indications were used. The follow-up duration was 24 months. The primary outcome was a 4-point composite success classification. Other validated clinical and radiographic assessments were also evaluated.

RESULTS

The investigational group (n = 182) was compared with patients who underwent ACDF (n = 170) in a historical control group using propensity score analysis. The overall composite success rate was statistically significantly greater in the cTDR group compared with the ACDF group (86.7% vs 77.1%; p < 0.05). The mean Neck Disability Index scores improved significantly in both groups, with cTDR significantly lower at some follow-up points. At the 24-month follow-up, a minimum 15-point improvement in Neck Disability Index scores was achieved in 92.9% of the cTDR group and 83.5% of the ACDF group (p > 0.05). In both groups, neck and arm pain scores improved significantly (p < 0.05) by 6 weeks and improvement was maintained throughout follow-up. Segmental range of motion was maintained at both treated segments in the cTDR group. MRI performed in the cTDR group at 24 months postoperatively found minimal changes in facet joint degeneration. The rate of subsequent surgical intervention was 2.2% in the cTDR group and 8.8% in the ACDF group.

CONCLUSIONS

This study adds to the growing body of literature supporting cTDR for 2-level cervical disc disease with radiculopathy or myelopathy. cTDR showed a superior overall success rate compared to ACDF, while maintaining motion. These results support that the Simplify disc is a viable alternative to ACDF in appropriately selected patients with 2-level cervical spondylosis.

Cervical Total Disk Replacement: Available Implant Size Matters

STUDY DESIGN

This study was a post hoc analysis of data collected from 2 Food and Drug Administration (FDA) Investigational Device Exemption (IDE) trials.

OBJECTIVE

The purposes of this study were to: (1) measure disk space heights adjacent to the level to be treated with a total disk replacement (TDR); (2) analyze cervical disk space heights to be replaced with TDR; and (3) investigate the frequency of use of a smaller height TDR when available.

SUMMARY OF BACKGROUND DATA

Cervical TDR produces outcomes noninferior or superior to anterior cervical discectomy and fusion. While the restoration of the height of a collapsed, degenerated disk is a surgical goal, there are potential problems with overdistracting the segment with an implant.

METHODS

Disk heights were measured using radiographs from the 1-level Simplify Cervical Artificial Disk IDE trial, producing values for 259 levels adjacent to the treated level and 162 treated levels. The device is available in 4, 5, and 6 mm heights. The 4 mm height became available only after treatment was 13% complete in the single-level trial and was available for all of the 2-level trial.

RESULTS

Measurements of 259 adjacent levels found that 55.2% of disk spaces had a height of <4 mm. Among operated levels, 82.7% were <4 mm. When a 4 mm TDR was available, it was used in 38.4% of operated levels in the 1-level trial and 54.3% of levels in the 2-level trial.

CONCLUSIONS

Among nonoperated levels, 55.2% were of height <4 mm, suggesting that TDRs of greater heights may potentially overdistract the disk space. The 4 mm TDR was selected by surgeons in 49.4% of all implanted levels, suggesting a preference for smaller TDR height. Further investigation is warranted to determine if the lower height implants are related to clinical and/or radiographic outcomes.

LEVEL OF EVIDENCE

Level III.

Indirect Decompression for the Treatment of Degenerative Lumbar Stenosis

BACKGROUND

Surgical treatment of symptomatic lumbar stenosis has traditionally included laminectomy for direct decompression. With increasing options for lumbar interbody fusion, there has been growing interest in indirect decompression to treat degenerative stenosis. The primary purpose of this study was to determine whether indirect decompression via anterior lumbar interbody fusion (ALIF) can provide symptomatic relief in patients with lumbar spinal stenosis. Secondary purposes were to (1) identify risk factors for failure of indirect decompression and (2) to identify risk factors for failure to obtain relief and to compare outcomes between patients undergoing stand-alone ALIF versusand those in whom ALIF was supplemented with posterior instrumentation.

METHODS

Chart review was performed on a consecutive series of 568 patients undergoing single-level ALIF without posterior decompression to treat degenerative stenosis during a 5-year period. Failure of indirect decompression was defined as return to the operating room for direct decompression. Subgroup analysis was performed to compare patients who underwent stand-alone ALIF (n = 247) vs those in whom supplemental posterior instrumentation was used (ALIF + PI; n = 321).

RESULTS

Reoperation due to failure of indirect decompression occurred in 4.0% (23/568) of patients. The only factor related to failure was age. Patients older than 60 years were more likely to fail indirect decompression than were younger patients (7.0% vs 3.1%, P < 0.05). ALIF and ALIF + PI subgroups both improved significantly when comparing preoperative to postoperative mean scores on Oswestry Disability Index (ODI), back pain, and leg pain (all P < 0.01). There were no significant differences between these groups, including reoperation rate for direct decompression.

CONCLUSIONS

Indirect decompression via ALIF was effective in treating appropriately selected patients with degenerative lumbar spinal stenosis. Older patients are at higher risk for failure of indirect decompression-potentially because of greater osseous stenosis as well as subsidence due to age-related diminished bone density with subsequent loss of distraction.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

This study supports that indirect decompression via ALIF is a viable alternative to direct decompression in appropriately selected patients with degenerative stenosis.

Incidence and Resolution Strategies for Early-Onset Postoperative Leg Pain Following Lumbar Total Disc Replacement

BACKGROUND

Lumbar total disc replacement (TDR) has produced results similar or superior to fusion in treating symptomatic disc degeneration. Some patients have reported onset of leg pain early after surgery. Little information is available specifically on this problem. The purpose of this study was to investigate the incidence of early-onset postoperative leg pain following lumbar TDR and to describe strategies for its treatment.

METHODS

The study was based on a post hoc analysis of prospectively collected adverse event data from 283 patients in the activL Food and Drug Administration investigational device exemption study. Early-onset leg pain was defined as occurring between 0 and 4 weeks postprocedure, and the baseline visual analog scale score in the affected leg(s) was <25 (of 100). The treatment types these patients received were analyzed.

RESULTS

Among 283 patients, 26 (9.2%) had an early-onset leg pain event. The majority of these events resolved (20/26, 76.9%). Of those resolving, 55% (11/20) did so within 3 months. Most patients received at least 1 drug treatment for leg pain (92.3%). Of those receiving drug therapy, the most common type was neurogenic (61.5%), followed by narcotics (46.2%). Steroid use was prescribed in 30.8%. The majority of resolved cases were not on narcotics and resolved with neurogenic drugs. Three patients went on to have surgery, none of whom benefited from it. Age, body mass index, and baseline disability scores were predictive of time to resolution.

CONCLUSION

Early-onset postoperative leg pain occurred in approximately 10% of lumbar TDR patients. The majority of events resolved, often within 3 months. Treatment with conservative care, including medication(s), was more effective in resolving symptoms rather than surgery.

CLINICAL RELEVANCE

This study provides useful information for providers and patients on the incidence, treatment, and resolution of leg pain with onset after lumbar TDR and not related to direct neural compression identified by imaging.

LEVEL OF EVIDENCE

2.

Cervical Total Disc Replacement: Novel Devices

This article reviews the available literature for novel cervical total disc replacement devices, including ones which are available inside and outside of the United States. It includes biomechanical consideration as well as design characteristics and clinical data when available.

Single-Level Cervical Disc Replacement Using a PEEK-on-Ceramic Implant: Results of a Multicenter FDA IDE Trial With 24-Month Follow-up

BACKGROUND

Many early cervical total disc replacements (TDRs) produced motion through a ball-and-socket action, with metal endplates articulating with a plastic core. Polyetheretherketone (PEEK) is used increasingly for spinal implants due to its mechanical properties and lack of artifacts on imaging. A TDR was designed with titanium-coated PEEK endplates and a ceramic core. The purpose of this study was to compare this TDR with anterior cervical discectomy and fusion (ACDF) to treat single-level cervical disc degeneration.

METHODS

This was a prospective, nonrandomized, historically controlled, multicenter US Food and Drug Administration (FDA) Investigational Device Exemption (IDE) trial. Patients received the PEEK-on-ceramic Simplify_® Cervical Artificial Disc (n = 150). The historic control group included 117 propensity-matched ACDF patients from an earlier IDE trial. The primary outcome was a composite success classification at the 24-month follow-up. Outcome measures included the Neck Disability Index (NDI), neurological status, adverse events, subsequent surgery, a visual analog scale assessing neck and arm pain, and the Dysphagia Handicap Index. Radiographic assessment included flexion/extension range of motion and heterotopic ossification. Facet joints were assessed at 24 months using MRI.

RESULTS

The success rate was significantly greater in the TDR group vs the ACDF group (93.0% vs 73.6%; P < .001). Mean NDI, neck pain, and arm pain scores improved significantly in both groups at all follow-up points. Mean NDI scores in the TDR group were significantly lower than ACDF scores at all follow-up points. There were no significant differences in the rates of serious adverse events. The range of motion of the TDR level had increased significantly by 3 months and remained so throughout follow-up. Facet joint assessment by MRI in the TDR group showed little change from preoperation.

CONCLUSIONS

The TDR had an acceptable safety profile and a significantly greater composite success rate than ACDF. These results support that the PEEK-on-ceramic TDR is a viable alternative to ACDF for single-level symptomatic disc degeneration.

CLINICAL RELEVANCE

This study found that the PEEK-on-ceramic TDR is a viable treatment for symptoms related to cervical disc degeneration and offers similar or superior outcomes compared with fusion.

LEVEL OF EVIDENCE

2.

Progression of Adjacent-level Degeneration After Lumbar Total Disc Replacement: Results of a Post-hoc Analysis of Patients With Available Radiographs From a Prospective Study With 5-year Follow-up

STUDY DESIGN

Post-hoc analysis of 5-year follow-up data from a randomized, multicenter trial.

OBJECTIVE

The aim of this study was to investigate the incidence of progression in radiographic adjacent-level degeneration (ΔALD) from preoperative assessment to 5 years after total disc replacement (TDR) and the relationship of these changes with range of motion and clinical adjacent-level disease. A secondary objective was to compare adjacent-level degeneration (ALD) outcomes between TDR and fusion.

SUMMARY OF BACKGROUND DATA

Fusion is associated with high rates of ALD in symptomatic lumbar disc degeneration. TDR may reduce this risk.

METHODS

In total, 175 patients with single-level, symptomatic, lumbar disc degeneration who had received activL or ProDisc-L and had a preoperative and 5-year postoperative radiograph available were included. Over 5-year follow-up, ΔALD was defined as an increase in ALD of ≥1 grade and clinical ALD was defined as surgical treatment at the level adjacent to an index TDR. Matching-adjusted indirect comparisons were conducted to compare ALD outcomes after TDR (current trial) with those after fusion (published trial).

RESULTS

At 5-year follow-up, 9.7% (17/175) of TDR patients had ΔALD at the superior level. In patients with preoperative ALD at the superior level, most (88% [23/26]) showed no radiographic progression over 5 years. The rate of clinical ALD was 2.3% (4/175) and none of these patients had ALD at baseline. For each degree of range of motion gained at the TDR level, there was a consistent decrease in the percentage of patients with ΔALD. After matching and adjustment of baseline characteristics, TDR had a significantly lower likelihood of ΔALD than fusion (odds ratio 0.32; 95% confidence interval 0.13, 0.76).

CONCLUSION

The rates of ΔALD and clinical ALD in this TDR population were similar to those previously reported in the literature for TDR at 5-year follow-up. TDR had a significantly lower rate of ΔALD than fusion.

LEVEL OF EVIDENCE

3.

Prospective, randomized multicenter study of cervical arthroplasty versus anterior cervical discectomy and fusion: 5-year results with a metal-on-metal artificial disc

OBJECTIVE

Seven cervical total disc replacement (TDR) devices have received FDA approval since 2006. These devices represent a heterogeneous assortment of implants made from various biomaterials with different biomechanical properties. The majority of these devices are composed of metallic endplates with a polymer core. In this prospective, randomized multicenter study, the authors evaluate the safety and efficacy of a metal-on-metal (MoM) TDR (Kineflex|C) versus anterior cervical discectomy and fusion (ACDF) in the treatment of single-level spondylosis with radiculopathy through a long-term (5-year) follow-up.

METHODS

An FDA-regulated investigational device exemption (IDE) pivotal trial was conducted at 21 centers across the United States. Standard validated outcome measures including the Neck Disability Index (NDI) and visual analog scale (VAS) for assessing pain were used. Patients were randomized to undergo TDR using the Kineflex|C cervical artificial disc or anterior cervical fusion using structural allograft and an anterior plate. Patients were evaluated preoperatively and at 6 weeks and 3, 6, 12, 24, 36, 48, and 60 months after surgery. Serum ion analysis was performed on a subset of patients randomized to receive the MoM TDR.

RESULTS

A total of 269 patients were enrolled and randomly assigned to undergo either TDR (136 patients) or ACDF (133 patients). There were no significant differences between the TDR and ACDF groups in terms of operative time, blood loss, or length of hospital stay. In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 60-month follow-up (both p < 0.01). Similarly, VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 60-month follow-up (both p < 0.01). There were no significant changes in outcomes between the 24- and 60-month follow-ups in either group. Range of motion in the TDR group decreased at 3 months but was significantly greater than the preoperative mean value at the 12- and 24-month follow-ups and remained significantly improved through the 60-month period. There were no significant differences between the 2 groups in terms of reoperation/revision surgery or device-/surgery-related adverse events. The serum ion analysis revealed cobalt and chromium levels significantly lower than the levels that merit monitoring.

CONCLUSIONS

Cervical TDR with an MoM device is safe and efficacious at the 5-year follow-up. These results from a prospective randomized study support that Kineflex|C TDR as a viable alternative to ACDF in appropriately selected patients with cervical radiculopathy.

Clinical trial registration no.: NCT00374413 (clinicaltrials.gov)

Comparison of 1-Level Versus 2-Level Anterior Cervical Discectomy and Fusion: Clinical and Radiographic Follow-Up at 60 Months

STUDY DESIGN

This study represents a posthoc analysis of data collected from 2 control arms of a prospective, randomized study.

OBJECTIVE

The purpose of this study was to compare results of patients undergoing 1- versus 2-level anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

For single-level ACDF, reported outcomes have generally been good; however, results for 2 levels have been less consistent.

METHODS

This 60-month follow-up study was based on data from the prospective Food and Drug Administration regulated Mobi-C artificial disc trial. Serving as the control, ACDF was performed at 1 level in 81 patients and 2 levels in 105 patients. Study selection criteria, fusion technique, and outcome measures were identical, with the only exception being the number of levels that were pathological and operated.

RESULTS

Neck Disability Index (NDI) scores, visual analog scales assessing neck and arm pain, and SF-12 scores improved significantly in both groups. Significant differences were observed between groups on NDI and SF-12 PCS scores through 60 months. Fusion rates were 93.3% in the 1-level group and 86.1% in the 2-level (60 months, not significantly different). Adjacent segment degeneration occurred in 54.7% of patients at the superior level and 44.7% at the inferior segment in the 1-level group and 70.8%, and 55.0% respectively in 2-level patients (trend at superior level; 0.05 < P < 0.10). Subsequent index level surgery was performed in 11.1% of single-level patients versus 16.2% of the 2-level group (not significantly different).

CONCLUSION

One- and 2-level ACDF groups improved significantly and maintained improvement throughout 60 month follow-up. When comparing groups, outcomes were often similar, though the 1-level group demonstrated higher fusion rates at 6 and 12 months, greater improvement in NDI scores from 18 to 60-month follow-up, and greater improvement in SF-12 PCS from 12 to 60 months.

Prospective, Randomized Comparison of One-level Mobi-C Cervical Total Disc Replacement vs. Anterior Cervical Discectomy and Fusion: Results at 5-year Follow-up

INTRODUCTION

There is increasing interest in the role of cervical total disc replacement (TDR) as an alternative to anterior cervical discectomy and fusion (ACDF). Multiple prospective randomized studies with minimum 2 year follow-up have shown TDR to be at least as safe and effective as ACDF in treating symptomatic degenerative disc disease at a single level. The purpose of this study was to compare outcomes of cervical TDR using the Mobi-C(®) with ACDF at 5-year follow-up.

METHODS

This prospective, randomized, controlled trial was conducted as a Food and Drug Administration regulated Investigational Device Exemption trial across 23 centers with 245 patients randomized (2:1) to receive TDR with Mobi-C(®) Cervical Disc Prosthesis or ACDF with anterior plate and allograft. Outcome assessments included a composite overall success score, Neck Disability Index (NDI), visual analog scales (VAS) assessing neck and arm pain, Short Form-12 (SF-12) health survey, patient satisfaction, major complications, subsequent surgery, segmental range of motion, and adjacent segment degeneration.

RESULTS

The 60-month follow-up rate was 85.5% for the TDR group and 78.9% for the ACDF group. The composite overall success was 61.9% with TDR vs. 52.2% with ACDF, demonstrating statistical non-inferiority. Improvements in NDI, VAS neck and arm pain, and SF-12 scores were similar between groups and were maintained from earlier follow-up through 60 months. There was no significant difference between TDR and ACDF in adverse events or major complications. Range of motion was maintained with TDR through 60 months. Device-related subsequent surgeries (TDR: 3.0%, ACDF: 11.1%, p<0.02) and adjacent segment degeneration at the superior level (TDR: 37.1%, ACDF: 54.7%, p<0.03) were significantly lower for TDR patients.

CONCLUSIONS

Five-year results demonstrate the safety and efficacy of TDR with the Mobi-C as a viable alternative to ACDF with the potential advantage of lower rates of reoperation and adjacent segment degeneration, in the treatment of one-level symptomatic cervical degenerative disc disease.

CLINICAL RELEVANCE

This prospective, randomized study with 5-year follow-up adds to the existing literature indicating that cervical TDR is a viable alternative to ACDF in appropriately selected patients.

LEVEL OF EVIDENCE

This is a Level I study.

Evaluation of Decompression and Interlaminar Stabilization Compared with Decompression and Fusion for the Treatment of Lumbar Spinal Stenosis: 5-year Follow-up of a Prospective, Randomized, Controlled Trial

INTRODUCTION

If nonoperative treatment for lumbar stenosis fails, surgery may be considered. This traditionally includes decompression often combined with fusion. Desire for less extensive surgery led to developing new techniques and implants, including an interlaminar device designed with the goal of providing segmental stability without fusion, following decompression. The purpose of this study was to investigate 5-year outcomes associated with an interlaminar device.

METHODS

This prospective, randomized, controlled trial was conducted at 21 centers. Patients with moderate to severe lumbar stenosis at one or two contiguous levels and up to Grade I spondylolisthesis were randomized (2:1 ratio) to decompression and interlaminar stabilization (D+ILS; n=215) using the coflex(®) Interlaminar Stabilization(®) device (Paradigm Spine, LLC) or decompression and fusion with pedicle screws (D+PS; n=107). Clinical evaluations were made preoperatively and at 6 weeks and 3, 6, 12, 18, 24, 36, 48, and 60 months postoperatively. Overall Food and Drug Administration success criteria required that a patient meet 4 criteria: 1) >15 point improvement in Oswestry Disability Index (ODI) score; 2) no reoperation, revision, removal, or supplemental fixation; 3) no major device-related complication; and 4) no epidural steroid injection after surgery.

RESULTS

At 5 years, 50.3% of D+ILS vs. 44% of D+PS patients (p>0.35) met the composite success criteria. Reoperation/revision rates were similar in the two groups (16.3% vs. 17.8%; p >0.90). Both groups had statistically significant improvement through 60 months in ODI scores with 80.6% of D+ILS patients and 73.2% of D+PS patients demonstrating >15 point improvement (p>0.30). VAS, SF-12, and ZCQ scores followed a similar pattern of maintained significant improvement throughout follow-up. On the SF-12 and ZCQ, D+ILS group scores were statistically significantly better during early follow-up compared to D+PS. In the D+ILS group, foraminal height, disc space height, and range of motion at the index level were maintained through 5 years.

CONCLUSION

Both treatment groups achieved and maintained statistically significant improvements on multiple outcome assessments throughout 5-year follow-up. On some clinical measures, there were statistically significant differences during early follow-up favoring D+ILS. At no point were there significant differences favoring D+PS. Results of this 5-year follow-up study demonstrate that decompression and interlaminar stabilization with coflex is a viable alternative to traditional decompression and fusion in the treatment of patients with moderate to severe stenosis at one or two lumbar levels.

LEVEL OF EVIDENCE AND ETHICAL STATEMENTS

This is a Level I study. Institutional approval was received at each of the sites participating in the trial. Each patient gave informed consent to participate in the trial.

Restoration of Cervical Alignment is Associated with Improved Clinical Outcome after One and Two Level Anterior Cervical Discectomy and Fusion

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) remains the standard of care for patients with cervical radiculopathy who are unresponsive to conservative care. However, the maintenance and restoration of cervical alignment as a predictive factor for outcome has not yet been fully evaluated. The purpose of this study was to evaluate the impact of maintaining or restoring cervical alignment on one and two level ACDF patients' outcome.

METHODS

Data were collected from 104 patients who underwent one and two level ACDF. Cervical alignment was measured preoperatively and at follow-up visits. The patients were classified into three groups based on the postoperative change of their cervical alignment. Neck pain, arm pain, and Neck Disability Index (NDI) scores were obtained preoperatively and at the latest follow-up visit. Incidences of adjacent segment degeneration (ASD) and reoperations because of ASD were recorded.

RESULTS

There were 64 patients in the Maintained group, 17 patients in the Restored group and 23 patients in the Kyphotic group. Pre-operatively, the neck pain scores, arm pain scores and NDI scores were not statistically different among the three groups (p>0.05). On average at 12 months follow-up, the neck pain scores improved by 2.7, 4.2, and 2.7 points respectively in the three groups (p>0.05). The patients' arm pain scores improved by 2.1, 2.4, and 2.8 points respectively (p>0.05). NDI scores improved by 12, 31 and 13.7 points respectively (p<0.05). The incidences of ASD and reoperations because of ASD were 16%, 12% and 35% respectively (p>0.05).

CONCLUSIONS

The patients with restored cervical alignment had significantly greater NDI improvement and relatively better neck pain improvement. There was a trend for patients who had unchanged cervical kyphosis to have a higher incidence of ASD. Our study suggests that restoration of cervical alignment will contribute to improved clinical outcome in the patients who have one and two level ACDF surgeries.

LEVEL OF EVIDENCE

This is a level III study.

A proposed set of metrics for standardized outcome reporting in the management of low back pain

BACKGROUND AND PURPOSE

Outcome measurement has been shown to improve performance in several fields of healthcare. This understanding has driven a growing interest in value-based healthcare, where value is defined as outcomes achieved per money spent. While low back pain (LBP) constitutes an enormous burden of disease, no universal set of metrics has yet been accepted to measure and compare outcomes. Here, we aim to define such a set.

PATIENTS AND METHODS

An international group of 22 specialists in several disciplines of spine care was assembled to review literature and select LBP outcome metrics through a 6-round modified Delphi process. The scope of the outcome set was degenerative lumbar conditions.

RESULTS

Patient-reported metrics include numerical pain scales, lumbar-related function using the Oswestry disability index, health-related quality of life using the EQ-5D-3L questionnaire, and questions assessing work status and analgesic use. Specific common and serious complications are included. Recommended follow-up intervals include 6, 12, and 24 months after initiating treatment, with optional follow-up at 3 months and 5 years. Metrics for risk stratification are selected based on pre-existing tools.

INTERPRETATION

The outcome measures recommended here are structured around specific etiologies of LBP, span a patient's entire cycle of care, and allow for risk adjustment. Thus, when implemented, this set can be expected to facilitate meaningful comparisons and ultimately provide a continuous feedback loop, enabling ongoing improvements in quality of care. Much work lies ahead in implementation, revision, and validation of this set, but it is an essential first step toward establishing a community of LBP providers focused on maximizing the value of the care we deliver.

Development of a novel radiographic measure of lumbar instability and validation using the facet fluid sign

BACKGROUND

Lumbar spinal instability is frequently referenced in clinical practice and the scientific literature despite the lack of a standard definition or validated radiographic test. The Quantitative Stability Index (QSI) is being developed as a novel objective test for sagittal plane lumbar instability. The QSI is calculated using lumbar flexion-extension radiographs. The goal of the current study was to use the facet fluid sign on MRI as the "gold standard" and determine if the QSI is significantly different in the presence of the fluid sign.

METHODS

Sixty-two paired preoperative MRI and flexion-extension exams were obtained from a large FDA IDE study. The MRI exams were assessed for the presence of a facet fluid sign, and the QSI was calculated from sagittal plane intervertebral rotation and translation measurements. The QSI is based on the translation per degree of rotation (TPDR) and is calculated as a Z-score. A QSI > 2 indicates that the TPDR is > 2 std dev above the mean for an asymptomatic and radiographically normal population. The reproducibility of the QSI was also tested.

RESULTS

The mean difference between trained observers in the measured QSI was between -0.28 and 0.36. The average QSI was significantly (P = 0.047, one-way analysis of variance) higher at levels with a definite fluid sign (2.3±3.2 versus 0.60±2.4).

CONCLUSIONS

Although imperfect, the facet fluid sign observed may be the best currently available test for lumbar spine instability. Using the facet fluid sign as the "gold standard" the current study documents that the QSI can be expected to be significantly higher in the presence of the facet fluid sign. This supports that QSI might be used to test for sagittal plane lumbar instability.

CLINICAL RELEVANCE

A validated, objective and practical test for spinal instability would facilitate research to understand the importance of instability in diagnosis and treatment of low-back related disorders.

The fate of prospective spine studies registered on www.ClinicalTrials.gov

BACKGROUND CONTEXT

There has been concern expressed about research ethics with respect to not fully reporting data collected during clinical studies. One site available for all clinical trials is ClinicalTrials.gov. The original purpose of this site was to facilitate patients seeking a trial for the treatment of their particular condition. The internationally available site offers general information about the study, sponsor name, principal investigator, patient selection criteria, enrollment goal, study design, outcome measures, participating centers, initiation date, date posted, date completed, and other pertinent data. The site can be used to identify studies conducted for a particular condition or intervention.

PURPOSE

The purpose of this study was to investigate the fate of spine-related studies registered on www.ClinicalTrials.gov, with particular focus on the publication rate of completed trials.

STUDY DESIGN/SETTING

Analysis and classification of clinical studies posted on an international research registry Web page and literature search for related publications.

PATIENT SAMPLE

Not applicable.

OUTCOME MEASURES

The primary outcome measure was publication of the study registered on ClinicalTrials.gov.

METHODS

Multiple searches were conducted on ClinicalTrials.gov Web site to identify studies related to commonly treated spinal conditions, including herniated disc, degenerative disc disease, stenosis, and spondylolisthesis. Studies related to tumors, fractures, or that included nonspine conditions were not included. For studies classified as completed more than 18 months before this review, literature searches were conducted to determine if the results of the study had been published and factors related to publication. The author has no financial conflict related to this work.

RESULTS

There were 263 spine-related studies identified from searches on the ClinicalTrials.gov site. Data on the site had the studies classified as follows: 72 completed, 70 active, not recruiting (generally indicates collecting follow-up data), 74 recruiting, 11 recruiting by invitation, 13 not yet recruiting, 18 terminated, 4 withdrawn, and 1 suspended. Among the 72 studies indicated to be completed, 28 (38.9%) have been published. The mean time to publish was 27.9 months from the date of completion. Among unpublished studies, the mean length of time from study completion to the preparation of this article was 62.0 months. There was no difference in the likelihood of publication based on the geographic region of study origin or whether the study was registered before or after initiation. There were statistically significant relationships between the publication rate and the funding type as well as the research type (p<.05) with industrial-funded studies and those evaluating devices having a lower publication rate and those that were funded by a federal agency and comparing surgery to nonoperative care had the highest publication rates.

CONCLUSIONS

Although the 38.9% publication rate for spine-related studies found in this study appears low, it is in line with other studies reporting a 22.8% publication rate for arthroplasty trials and 43.2% for orthopedic trauma trials. In addition to ClinicalTrials.gov Web site fulfilling its original goal of providing patients information about clinical studies, it can also provide a means of tracking publication of prospective studies, changes to protocols, matching publication content to posted study design, and others and raise queries concerning the reasons for not publishing what appear to be well-designed studies. The posting of spine studies before initiation can increase transparency and ability to evaluate clinical trials in spine.

Clinical outcomes of a polyaxial interspinous fusion system

Background

Early interspinous process fixation constructs utilize rigid fixation plates with immobile spikes which increase the difficulty of device implantation when anatomic variations are encountered. Second generation systems have been designed with polyaxial properties with the goal of accommodating natural osseous anatomic variations to achieve optimal implant placement and fixation integrity. The purpose of this study was to evaluate clinical outcomes in patients treated with this device to supplement the biomechanical data from previous studies.

Methods

A retrospective, non-randomized, single-center chart review at or beyond the one year postoperative time point was conducted to collect preoperative and perioperative data on patients treated with a polyaxial intraspinous fixation system. A postoperative numerical pain rating scale and modified MacNab classification score were obtained from each patient in the cohort via phone survey.

Results

A total of 53 patients were included in the study. Median hospital stay was 2 days (range 1-7 days). There were no reported perioperative blood transfusions or cases of radiographic fracture/migration of the device at the 6 week post-operative time point. There was a significant improvement in pain index score in the overall patient study group and a satisfactory (excellent or good) MacNab result was obtained in 48% of all patients. Patients with preoperative pain scores greater than 8/10 reported more pain improvement than patients with preoperative pain scores less than 5 (0 points, p = 0.96, n = 8). Patients with a BMI less than 30 had significantly better MacNab outcome classifications than patients with a BMI greater than 30.

Conclusions

The polyaxial interspinous fusion system produces significant clinical improvement when employed to treat patients with stenosis, herniated disc, or low grade spondylolisthesis. This device can be implanted with a low complication rate and short postoperative hospital admission time. Patients with high pre-operative pain score and BMI under 30 can be predictors of better clinical outcome and should be considered prior to implantation.

Robotic assisted surgeries for the treatment of spine tumors

Background

Surgery plays an important role in the treatment of patients with metastatic or primary spine tumors. In recent years, various new techniques, such as robotic assisted spine surgery have been developed which has shown some promising results by improving the accuracy of spinal instrumentation and reducing potential complications. The purpose of this study was to evaluate our early experience using robotic guidance in the treatment of spinal tumors.

Methods

Data were collected from medical records for each surgery in which the robotic system was used to assist with biopsy, pedicle screw placement and/or vertebral augmentation in the treatment of spinal tumors. Patient's age, gender, diagnosis and surgical procedure were documented. The surgical time, estimated blood loss, peri-operative and post-operative complications were obtained. The visual analog scale (VAS) for back pain and leg pain were also recorded.

Results

A total of 9 consecutive patients (7 female, 2 male) were included in this study, beginning with the first case experience. The mean age of the patients was 60 years (range 47-69). All patients presented with thoracic or lumbar vertebral collapse and/or myelopathy. Robotic assisted posterior instrumentation was successfully performed in all patients. Robotic assisted vertebral augmentation was performed in 4 patients. The average number of levels instrumented was 5. The average surgery time (skin to skin) was 4 hours and 24 minutes and the mean blood loss was 319 ml. There were no complications perioperatively or through the latest follow-up. Seven of the 9 patients reported improved back pain and/or leg pain at the latest follow-up and the data were not available in two patients.

Conclusions

The published complication rates of spinal tumor surgeries range between 5.3% and 19%. With robotic assistance, the surgical complication rate appears improved over the historical figures. Our study shows that the robotic system was safe and performed as desired in the treatment of metastatic and primary spine tumors. These results support that further evaluation in a larger series of patients.

Indications for lumbar total disc replacement: selecting the right patient with the right indication for the right total disc

Summary of Background Data

As with any surgery, care should be taken to determine patient selection criteria for lumbar TDR based on safety and optimizing outcome. These goals may initially be addressed by analyzing biomechanical implant function and early clinical experience, ongoing evaluation is needed to refine indications.

Objective

The purpose of this work was to synthesize information published on general indications for lumbar TDR. A secondary objective was to determine if indications vary for different TDR designs.

Methods

A comprehensive literature search was conducted to identify lumbar TDR articles. Articles were reviewed and patient selection criteria and indications were synthesized.

Results

With respect to safety, there was good agreement in the literature to exclude patients with osteopenia/osteoporosis or fracture. Risk of injury to vascular structures due to the anterior approach was often addressed by excluding patients with previous abdominal surgery in the area of disc pathology or increased age. The literature was very consistent on the primary indication for TDR being painful disc degeneration unresponsive to at least 6 months of nonoperative care. Literature investigating the impact of previous spine surgery was mixed; however, prior surgery was not necessarily a contra-indication, provided the patient otherwise met selection criteria. The literature was mixed on setting a minimum preoperative disc height as a selection criterion. There were no publications investigating whether some patients are better/worse candidates for specific TDR designs. Based on the literature a proposal for patient selection criteria is offered.

Conclusions

Several TDR indications and contra-indications are widely accepted. No literature addresses particular TDR design being preferable for some patients. As with any spine surgery, ongoing evaluation of TDR outcomes will likely lead to more detailed general and device design specific indications.

Use of an ultrasonic osteotome device in spine surgery: experience from the first 128 patients

INTRODUCTION

The ultrasonic BoneScalpel is a tissue-specific device that allows the surgeon to make precise osteotomies while protecting collateral or adjacent soft tissue structures. The device is comprised of a blunt ultrasonic blade that oscillates at over 22,500 cycles/s with an imperceptible microscopic amplitude. The recurring impacts pulverize the noncompliant crystalline structure resulting in a precise cut. The more compliant adjacent soft tissue is not affected by the ultrasonic oscillation. The purpose of this study is to report the experience and safety of using this ultrasonic osteotome device in a variety of spine surgeries.

METHODS

Data were retrospectively collected from medical charts and surgical reports for each surgery in which the ultrasonic scalpel was used to perform any type of osteotomy (facetectomy, laminotomy, laminectomy, en bloc resection, Smith Petersen osteotomy, pedicle subtraction osteotomy, etc.). The majority of patients had spinal stenosis, degenerative or adolescent scoliosis, pseudoarthrosis, adjacent segment degeneration, and spondylolisthesis et al. Intra-operative complications were also recorded.

RESULTS

A total of 128 consecutive patients (73 female, 55 male) beginning with our first case experience were included in this study. The mean age of the patients was 58 years (range 12-85 years). Eighty patients (62.5 %) had previous spine surgery and/or spinal deformity. The ultrasonic scalpel was used at all levels of the spine and the average levels operated on each patient were 5. The mean operation time (skin to skin) was 4.3 h and the mean blood loss was 425.4 ml. In all cases, the ultrasonic scalpel was used to create the needed osteotomies to facilitate the surgical procedure without any percussion on the spinal column or injury to the underlying nerves. There was a noticeable absence of bleeding from the cut end of the bone consistent with the ultrasonic application. There were 11 instances of dural injuries (8.6 %) and two of which were directly associated with the use of ultrasonic device. In no procedure was the use of the ultrasonic scalpel abandoned for use of another instrument due to difficulty in using the device or failure to achieve the desired osteotomy.

CONCLUSIONS

Overall, the ultrasonic scalpel was safe and performed as desired when used as a bone cutting device to facilitate osteotomies in a variety of spine surgeries. However, caution should be taken to avoid potential thermal injury and dural tear. If used properly, this device may decrease the risk of soft tissue injury associated with the use of high speed burrs and oscillating saws during spine surgery.

Robotic-assisted pedicle screw placement: lessons learned from the first 102 patients

INTRODUCTION

Surgeons' interest in image and/or robotic guidance for spinal implant placement is increasing. This technology is continually improving and may be particularly useful in patients with challenging anatomy. Only through careful clinical evaluation can its successful applications, limitations, and areas for improvement be defined. This study evaluates the outcomes of robotic-assisted screw placement in a consecutive series of 102 patients.

METHODS

Data were recorded from technical notes and operative records created immediately following each surgery case, in which the robotic system was used to guide pedicle screw placement. All cases were performed at the same hospital by a single surgeon. The majority of patients had spinal deformity and/or previous spine surgery. Each planned screw placement was classified as: (1) successful/accurately placed screw using robotic guidance; (2) screw malpositioned using robot; (3) use of robot aborted and screw placed manually; (4) planned screw not placed as screw deemed non essential for construct stability. Data from each case were reviewed by two independent researchers to indentify the diagnosis, number of attempted robotic guided screw placements and the outcome of the attempted placement as well as complications or reasons for non-placement.

RESULTS

Robotic-guided screw placement was successfully used in 95 out of 102 patients. In those 95 patients, 949 screws (87.5 % of 1,085 planned screws) were successfully implanted. Eleven screws (1.0 %) placed using the robotic system were misplaced (all presumably due to "skiving" of the drill bit or trocar off the side of the facet). Robotic guidance was aborted and 110 screws (10.1 %) were manually placed, generally due to poor registration and/or technical trajectory issues. Fifteen screws (1.4 %) were not placed after intraoperative determination that the screw was not essential for construct stability. The robot was not used as planned in seven patients, one due to severe deformity, one due to very high body mass index, one due to extremely poor bone quality, one due to registration difficulty caused by previously placed loosened hardware, one due to difficulty with platform mounting and two due to device technical issues.

CONCLUSION

Of the 960 screws that were implanted using the robot, 949 (98.9 %) were successfully and accurately implanted and 11 (1.1 %) were malpositioned, despite the fact that the majority of patients had significant spinal deformities and/or previous spine surgeries. "Tool skiving" was thought to be the inciting issue with the misplaced screws. Intraoperative anteroposterior and oblique fluoroscopic imaging for registration is critical and was the limiting issue in four of the seven aborted cases.

Cervical total disc replacement using a novel compressible prosthesis: Results from a prospective Food and Drug Administration-regulated feasibility study with 24-month follow-up

Background

Anterior cervical fusion, an established procedure to treat cervical radiculopathy, sacrifices the natural function of the disc, while placing increased stresses on adjacent spinal levels. In contrast, the cervical total disc replacement (cTDR) maintains motion and decreases adjacent-level stresses. The purpose of this study was to investigate the safety and effectiveness of a next-generation cTDR device in patients with symptomatic cervical radiculopathy.

Methods

This is a multicenter Food and Drug Administration–regulated feasibility study to evaluate safety and effectiveness of the M6-C Artificial Cervical Disc for the treatment of patients with symptomatic cervical radiculopathy at 1 or 2 levels from C3 to C7. Neck Disability Index (NDI), visual analog scales (VAS) assessing neck and arm pain, Short Form 36 Health Survey (SF-36), safety, and radiographic outcomes were assessed preoperatively, at 6 weeks and 3, 6, 12, and 24 months postoperatively.

Results

Thirty patients were enrolled at 3 clinical sites. Patients were implanted at either 1 or 2 levels. Mean NDI improved from 67.8 to 20.8 (P < .0001) at 24 months. Significant improvement was also observed through 24-month follow-up in neck and arm pain VAS (P < .0001) and in physical (P < .005) and mental component scores of the SF-36 at 3, 6, and 12 months (P < .008). There were no serious adverse events related to the device or procedure as adjudicated by an independent clinical events committee. Radiographically, disc space height increased more than 50% with a correlative increase in the postoperative disc angle. Range of motion decreased slightly from baseline during early follow-up but increased slightly and were maintained throughout the follow-up period.

Conclusions

The M6-C cervical artificial disc represents a new generation of cTDR design. Results of this study found the M6-C device to produce positive clinical and radiographic outcomes similar to other cTDRs, warranting further investigation.

Analysis of adjacent segment reoperation after lumbar total disc replacement

Background

Fusion has long been used for treating chronic back pain unresponsive to nonoperative care. However, potential development of adjacent segment degeneration resulting in reoperation is a concern. Total disc replacement (TDR) has been proposed as a method for addressing back pain and preventing or reducing adjacent segment degeneration. The purpose of the study was to determine the reoperation rate at the segment adjacent to a level implanted with a lumbar TDR and to analyze the pre-TDR condition of the adjacent segment.

Methods

This study was based on a retrospective review of charts and radiographs from a consecutive series of 1000 TDR patients to identify those who underwent reoperation because of adjacent segment degeneration. Some of the patients were part of randomized studies comparing TDR with fusion. Adjacent segment reoperation data were also collected from 67 patients who were randomized to fusion in those studies. The condition of the adjacent segment before the index surgery was compared with its condition before reoperation based on radiographs, magnetic resonance imaging (MRI), and computed tomography.

Results

Of the 1000 TDR patients, 20 (2.0%) underwent reoperation. The mean length of time from arthroplasty to reoperation was 28.3 months (range, 0.5–85 months). Of the adjacent segments evaluated on preoperative MRI, 38.8% were normal, 38.8% were moderately diseased, and 22.2% were classified as having severe degeneration. None of these levels had a different grading at the time of reoperation compared with the pre-TDR MRI study. Reoperation for adjacent segment degeneration was performed in 4.5% of the fusion patients.

Conclusions

The 2.0% rate of adjacent segment degeneration resulting in reoperation in this study is similar to the 2.0% to 2.8% range in other studies and lower than the published rates of 7% to 18% after lumbar fusion. By carefully assessing the presence of pre-existing degenerative changes before performing arthroplasty, this rate may be reduced even more.

Minimally invasive trans-sacral approach to L5-S1 interbody fusion: Preliminary results from 1 center and review of the literature

BACKGROUND

Lumbar interbody fusion has long been used for the treatment of painful degenerative spinal conditions. The anterior approach is not feasible in some patients, and the posterior approach is associated with a risk of neural complications and possibly muscle injury. A trans-sacral technique was developed that allows access to the L5-S1 disc space. The purposes of this study were to investigate the clinical outcome of trans-sacral interbody fusion in a consecutive series of patients from 1 center and to perform a comprehensive review of the literature on this procedure.

METHODS

A literature search using PubMed was performed to identify articles published on trans-sacral axial lumbar interbody fusion (AxiaLIF). Articles reviewed included biomechanical testing, feasibility of the technique, and clinical results. The data from our center were collected retrospectively from charts for the consecutive series, beginning with the first case, of all patients undergoing fusion using the AxiaLIF technique. In most cases, posterior instrumentation was also used. A total of 41 patients with at least 6 months' follow-up were included (mean follow-up, 22.2 months). The primary clinical outcome measures were visual analog scales separately assessing back and leg pain and the Oswestry Disability Index. Radiographic assessment of fusion was also performed.

RESULTS

In the group of 28 patients undergoing single-level AxiaLIF combined with posterior fusion, the visual analog scale scores assessing back and leg pain and mean Oswestry Disability Index scores improved significantly (P < .01). In the remaining 13 patients, back pain improved significantly with a trend for improvement in leg pain. Reoperation occurred in 19.5% of patients; in half of these, reoperation was not related to the anterior procedure.

CONCLUSIONS

A review of the literature found that the AxiaLIF technique was similar to other fusion techniques with respect to biomechanical properties and produced acceptable clinical outcomes, although results varied among studies.

CLINICAL RELEVANCE

The AxiaLIF approach allows access to the L5-S1 interspace without violating the annulus or longitudinal ligaments and with minimal risk to dorsal neural elements. It may be a viable alternative to other approaches to interbody fusion at the L5-S1 level. It is important that the patients be selected carefully and surgeons are familiar with the presacral anatomy and the surgical approach.

Anterior discectomy and total disc replacement for three patients with multiple recurrent lumbar disc herniations

BACKGROUND CONTEXT

Although results of primary discectomy are generally excellent with relief of leg pain, recurrent lumbar disc herniation is relatively common ranging from 5% to 25%. Patients with recurrent herniation may undergo revision surgery; however, this carries with it increased risks and lower success rates. Many surgeons will advocate a fusion in addition to repeat discectomy after the third recurrent herniated disc. With the approval of lumbar total disc arthroplasty, there now exists another option for the patient with three or more recurrent disc herniations to preserve motion, theoretically decrease the rate of adjacent-level disease, and ameliorate the patient's symptoms.

PURPOSE

The purpose of this case report is to describe our experience using total disc replacement (TDR) in three patients after prior partial hemilaminectomy and discectomy for the treatment of a third and fourth recurrent lumbar disc herniation.

STUDY DESIGN

This article is a report of three cases from a spine specialty center describing an alternative surgical technique for patients with multiple recurrent lumbar disc herniation.

METHODS

Comprehensive chart review of three patients with recurrent lumbar herniation who underwent TDR.

RESULTS

Anterior discectomy and TDR were undertaken, and at most recent follow-up (8-12 months), all patients had improvement of their visual analog scale and Oswestry Disability Index. No patient had postoperative complications or reoperation.

CONCLUSIONS

Recurrent disc herniation is a relatively common problem that may be difficult to treat. Traditionally, a patient presenting with three or more recurrent disc herniation may likely have undergone revision discectomy with fusion. The current case report suggests that TDR may be an alternative option in select patients.

Prospective, randomized, multicenter study of cervical arthroplasty: 269 patients from the Kineflex|C artificial disc investigational device exemption study with a minimum 2-year follow-up: clinical article

OBJECT

Cervical total disc replacement (CTDR) represents a relatively novel procedure intended to address some of the shortcomings associated with anterior cervical discectomy and fusion (ACDF) by preserving motion at the treated level. This prospective, randomized, multicenter study evaluates the safety and efficacy of a new metal-on-metal CTDR implant (Kineflex|C) by comparing it with ACDF in the treatment of single-level spondylosis with radiculopathy.

METHODS

The study was a prospective, randomized US FDA Investigational Device Exemption (IDE) pivotal trial conducted at 21 centers across the US. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS) scores, and a composite measure of clinical success. Patients were randomized to CTDR using the Kineflex|C (SpinalMotion, Inc.) cervical artificial disc or ACDF using structural allograft and an anterior plate.

RESULTS

A total of 269 patients were enrolled and randomly assigned to either CTDR (136 patients) or to ACDF (133 patients). There were no significant differences between the CTDR and ACDF groups when comparing operative time, blood loss, length of hospital stay, or the reoperation rate at the index level. The overall success rate was significantly greater in the CTDR group (85%) compared with the ACDF group (71%) (p = 0.05). In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 24-month follow-up (p < 0.0001). Similarly, the VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 24-month follow-up (p < 0.0001). The range of motion (ROM) in the CTDR group decreased at 3 months but was significantly greater than the preoperative mean at 12- and 24-month follow-up. The ROM in the ACDF group was significantly reduced by 3 months and remained so throughout the follow-up. Adjacent-level degeneration was also evaluated in both groups from preoperatively to 2-year follow-up and was classified as none, mild, moderate, or severe. Preoperatively, there were no significant differences between groups when evaluating the different levels of adjacent-level degeneration. At the 2-year follow-up, there were significantly more patients in the ACDF group with severe adjacent-level radiographic changes (p < 0.0001). However, there were no significant differences between groups in adjacent-level reoperation rate (7.6% for the Kineflex|C group and 6.1% for the ACDF group).

CONCLUSIONS

Cervical total disc replacement allows for neural decompression and clinical results comparable to ACDF. Kineflex|C was associated with a significantly greater overall success rate than fusion while maintaining motion at the index level. Furthermore, there were significantly fewer Kineflex|C patients showing severe adjacent-level radiographic changes at the 2-year follow-up. These results from a prospective, randomized study support that Kineflex|C CTDR is a viable alternative to ACDF in select patients with cervical radiculopathy.

Are electrodiagnostic study findings related to a patient's response to epidural steroid injection?

OBJECTIVE

To determine if improvements in pain after epidural steroid injections (ESIs) were related to electromyographic (EMG) findings in patients with radicular symptoms and clinical findings consistent with radiculopathy.

DESIGN

Retrospective chart review.

SETTING

Multisite spine clinic.

PATIENTS

Data were analyzed from 89 patients who had needle EMG within 6 months of ESI between 2005 and 2008.

METHODS

Clinical and demographic data and results of EMG testing from qualified patients were recorded from patient charts at least 10 days after ESI. Evidence of radiculopathy on EMG reports was classified as positive, normal, or equivocal. In all 3 EMG groups, the percentage of patients who had 50% improvement in leg pain after ESI was noted. As a secondary analysis, improvement in pre-ESI to post-ESI leg and back pain scores in the EMG groups were compared.

OUTCOME MEASUREMENTS

The clinical outcome measurements were visual analog scale (VAS) scores assessing leg and back pain. ESI relief was defined as at least 50% improvement in the VAS score assessing leg pain after the injection.

RESULTS

EMG findings were normal in 47.2%, positive in 31.5%, and equivocal in 21.3% of patients. No significant differences were found in the percentages of patients experiencing a positive response to the ESI with respect to EMG findings. Forty-three percent of patients with normal EMG findings (18/42), 25.0% of patients with positive EMG findings (7/28), and 31.6% patients with equivocal EMG findings (6/19) had relief after ESI. In all 3 EMG groups, a statistically significant improvement in mean VAS scores was found after ESI.

CONCLUSIONS

Mean leg and back pain scores improved significantly after ESI in all 3 EMG groups: those with positive, normal, and equivocal findings. Results of this study do not suggest that ESI is contraindicated in patients with normal EMG findings.

Twenty-four month follow-up for reporting results of spinal implant studies: Is this guideline supported by the literature?

Background

Traditionally, spine societies and journals have set guidelines requiring a minimum 24-month follow-up for reporting results of surgical implant studies. However, the basis for this particular time period is not clear. The purpose of this study was to analyze prospective spinal implant studies reporting data at multiple specific follow-up periods to determine if there were significant changes in the clinical outcome throughout the 24-month follow-up period.

Methods

A comprehensive literature search was conducted using PubMed as well as searching the FDA web page. Studies were evaluated to identify those meeting the inclusion criteria: involved at least 100 patients receiving a spinal implant with data reported at multiple pre-defined time periods post-operatively for at least 24-months. Data recorded from each study included, number of patients, diagnoses, implant used, outcome measures used, and the results reported. The primary outcome data were analyzed in the current study to determine the amount of change in scores, with particular focus on the six and 24-month follow-up periods.

Results

Only 7 studies met the inclusion criteria. All seven studies were FDA-regulated trials published since 1997. Six addressed the treatment of symptomatic disc degeneration and 1 involved patients with neurogenic claudication due to stenosis. The outcome measures in the studies varied but pain and function were frequently assessed. In none of the studies was there a significant deterioration in results between the 6 and 24-month follow-up periods. In fact, the only changes during the follow-up periods were slight, not statistically significant, improvements, with the exception of 1 scale in 1 study where a slight, not statistically significant, decrease in the extent of improvement on a physical function assessment was noted between 6 and 24 months. These results suggest a great deal of stability in the mean scores for various outcome measures between the 6 and 24 months in patients receiving spinal implants.

Conclusions

Although long-term follow-up is certainly desirable for any clinical outcome study, there appears to be no significant change in outcome measures between the 6-month and 24-month follow-ups. These results support that earlier dissemination of results may be appropriate without producing overly-optimistic reports.

Avascular necrosis of lumbar facet joints associated with bilateral facet fractures

BACKGROUND CONTEXT

Avascular necrosis is a commonly described condition caused by a disruption of blood supply to the bones, resulting in necrosis. Although common in joints of the extremities, it is seen less often in the spine. Risk factors for avascular necrosis include steroid use, alcohol consumption, smoking, scuba diving, thrombosis, hypercoagulability, and hypertension.

PURPOSE

The purpose was to report an unprecedented case of avascular necrosis of the lumbar facet joints and bilateral facet fractures.

STUDY DESIGN

This is a case report.

METHODS

The patient underwent L3-S1 decompression and L5-S1 discectomy, during which time avascular necrosis of the superior articular process of the L3-L4 facet joints was discovered. The patient then underwent spinal fusion with pedicle screw instrumentation. Pathologic examination of both right and left facet joints confirmed the diagnosis of avascular necrosis.

RESULTS

At 19-month follow up, the patient's leg and back pain had significantly improved. His spine appeared fused with no instability or implant failure.

CONCLUSION

We have presented a case of avascular necrosis of L3-L4 facet joints resulting in fracture and instability at the L3-L4 level of the spine, which was stabilized with an L3-L4 pedicle screw spinal fusion.

Relationship between the length of time off work preoperatively and clinical outcome at 24-month follow-up in patients undergoing total disc replacement or fusion

BACKGROUND CONTEXT

A recent study involving interbody fusion patients found that preoperative work status was significantly related to clinical outcome. In another study comparing the best and worst outcomes of total disc replacement, among a battery of variables analyzed, the only one that differentiated the best and worst outcome groups was the length of time off work before total disc replacement.

PURPOSE

The purpose of this study was to determine if there was a relationship between the length of time off work and treatment outcome at 24-month follow-up. If such a relationship existed, a secondary study objective would be to determine if a duration of work could be identified beyond which would be associated with compromised clinical outcome.

STUDY DESIGN AND SETTING

Data were collected prospectively from randomized clinical trials comparing total disc replacement with lumbar fusion conducted at a single site.

PATIENT SAMPLE

A database of 232 patients enrolled in one of two Food and Drug Administration-regulated trials comparing total disc replacement with fusion for the treatment of symptomatic disc degeneration was the basis of the study group. Only patients who had reached 24-month follow-up were included. The 28 patients who were not employed by choice preoperatively were not included in the analysis.

OUTCOME MEASURES

Primary outcome measures used were visual analog scales (VAS) assessing pain and Oswestry disability index.

METHODS

The length of time off work before surgery was recorded in weeks. The mean percentage improvement between preoperative and 24-month follow-up scores were analyzed.

RESULTS

There was a significant relationship between duration off work preoperatively and clinical outcome (p<.05). The length of time off work preoperatively was more strongly related to outcome than was surgery type, insurance type, job demand, or preoperative VAS and Oswestry scores. Further analysis of the data identified a window of approximately 0 to 13 weeks off work preoperatively that was related to significantly greater improvements on visual analog scales (VAS) and Oswestry scores after surgery compared with patients who were off work for more than 13 weeks preoperatively. Although the subgroup off work for more than 13 weeks improved significantly from their preoperative status, the improvement was not as great as in the subgroup off work for a shorter duration.

CONCLUSIONS

The results of this study found that patients off work for a longer duration before surgery improved significantly postoperatively, but had less favorable clinical outcomes than patients off work for a lesser duration. This study suggests a window of approximately 13 weeks off work before surgery after which clinical improvement is reduced. Implications of this finding may be that once a patient becomes unable to work for an extended period, more rigorous psychological screening may be in order as well as perhaps engaging in more rigorous rehabilitation after surgery. Further investigation is needed to determine if the 13 weeks identified in this study is applicable to other populations.

Comparison of 2-Level Versus 1-Level Total Disc Replacement: Results From a Prospective FDA-Regulated Trial

BACKGROUND

Fusion has been the traditional surgery for painful disc degeneration unresponsive to nonoperative care. Fusion rates may decline in multilevel procedures. Also, fusion may force additional stress onto adjacent discs. This effect may be amplified in multilevel procedures. Single-level total disc replacement (TDR) has been found to be as effective as fusion. There have been few published reports addressing 2-level TDR. The purpose of this study was to compare results of TDR at 2 levels to 1-level procedures.

METHODS

This report included the first consecutive 86 patients who had reached 24-month follow-up from among those enrolled in the ProDisc-L investigational device exemption (IDE) study of patients undergoing TDR at 1 level (N = 54) or at 2 levels (N = 32). Clinical outcome measures included visual analog scales (VAS) assessing pain, Oswestry Disability Index, satisfaction measured by VAS, and responses to the question regarding whether the patient would have the same surgery again.

RESULTS

Operative time and length of hospitalization were significantly less in the 1-level cases compared to 2 levels (61.6 min vs 97.8 min; and 1.89 days vs 2.44 days; P < .05). There was a trend for less blood loss in single-level cases (59.0 mL vs 79.2 mL) (.05 < P < .09). VAS and Oswestry scores were significantly improved in both groups postoperatively (by approximately 50%). At no follow-up were there significant differences in VAS, Oswestry, or patient satisfaction scores between the single- and 2-level patients. At all follow-ups, the mean satisfaction in both groups was greater than 7.5 on a scale of 0 to 10.

CONCLUSIONS

Patients undergoing 2-level TDR improved significantly postoperatively based on VAS and Oswestry scores, and there were no significant differences in outcome scores when comparing 1- and 2-level TDR.

CLINICAL RELEVANCE

This study suggests that 2-level TDR can be undertaken in appropriately selected patients and achieve results similar to singlelevel cases.

Two- to 3-Year Follow-Up of ProDisc-L: Results From a Prospective Randomized Trial of Arthroplasty Versus Fusion

Background

Although total disc replacement has been performed for years outside the United States, relatively little available data address clinical outcomes, particularly data from prospective studies. We report the 24- to 36-month follow-up of one center's experience with the ProDisc-L artificial disc as part of a prospective, randomized trial comparing total disc arthroplasty to combined anterior–posterior lumbar fusion.

Methods

The study involved clinical results for 157 patients from a single center enrolled in the US Food and Drug Administration–regulated trial comparing ProDisc-L to fusion. Only patients who had reached a minimum 24-month follow-up were included in the study. Patients were randomized to receive total disc replacement or circumferential fusion at 1 or 2 lumbar disc levels from L3 to S1, with specific inclusion and exclusion criteria. Data were collected preoperatively and at 6 weeks to 36 months postoperatively. The primary clinical outcome measures were Visual Analog Scale (VAS) scores to assess pain and Oswestry Disability Index (ODI) scores to measure function.

Results

The VAS and ODI scores in both treatment groups improved significantly as early as the 6-week followup visit and remained significantly improved throughout the 36-month follow-up period. Although a tendency was observed for the ProDisc-L scores to indicate more favorable outcome, the differences were not statistically significant. The proportion of patients who would have the same procedure again was greater in the total disc replacement group at all follow-up intervals, and significantly greater at the 6- month, 12-month, 24-month, and 36-month follow-up visits.

Conclusions

The results of this study indicate that the total disc replacement with ProDisc-L produces improvements in pain and function that are at least as good as those provided by circumferential fusion. During the long-term follow-up of 24 and 36 months, outcomes did not become less favorable compared with the early outcomes.

Clinical Relevance

We found that results of total disc replacement were at least as good as those achieved with combined instrumented anterior–posterior fusion for the treatment of painful disc degeneration. Favorable results were maintained during 24- and 36-month follow-up.

Failed back surgery syndrome: diagnostic evaluation

Failed back surgery syndrome is a common problem with enormous costs to patients, insurers, and society. The etiology of failed back surgery can be poor patient selection, incorrect diagnosis, suboptimal selection of surgery, poor technique, failure to achieve surgical goals, and/or recurrent pathology. Successful intervention in this difficult patient population requires a detailed history, precise physical examination, and carefully chosen diagnostic tests. The diagnostic evaluation should endeavor to accurately identify symptoms, rule out extraspinal causes, identify a specific spinal etiology, and assess the psychological state of the patient. Only after these factors have been assessed can further treatment be planned.

A prospective, randomized, multicenter Food and Drug Administration investigational device exemptions study of lumbar total disc replacement with the CHARITE artificial disc versus lumbar fusion: part I: evaluation of clinical outcomes

STUDY DESIGN

A prospective, randomized, multicenter, Food and Drug Administration-regulated Investigational Device Exemption clinical trial.

OBJECTIVES

The purpose of this study was to compare the safety and effectiveness of lumbar total disc replacement, using the CHARITE artificial disc (DePuy Spine, Raynham, MA), with anterior lumbar interbody fusion, for the treatment of single-level degenerative disc disease from L4-S1 unresponsive to nonoperative treatment.

SUMMARY OF BACKGROUND DATA

Reported results of lumbar total disc replacement have been favorable, but studies have been limited to retrospective case series and/or small sample sizes.

METHODS

Three hundred four (304) patients were enrolled in the study at 14 centers across the United States and randomized in a 2:1 ratio to treatment with the CHARITE artificial disc or the control group, instrumented anterior lumbar interbody fusion. Data were collected pre- and perioperatively at 6 weeks and at 3, 6, 12, and 24 months following surgery. The key clinical outcome measures were a Visual Analog Scale assessing back pain, the Oswestry Disability Index questionnaire, and the SF-36 Health Survey.

RESULTS

Patients in both groups improved significantly following surgery. Patients in the CHARITE artificial disc group recovered faster than patients in the control group. Patients in the CHARITE artificial disc group had lower levels of disability at every time interval from 6 weeks to 24 months, compared with the control group, with statistically lower pain and disability scores at all but the 24 month follow-up (P < 0.05). At the 24-month follow-up period, a significantly greater percentage of patients in the CHARITE artificial disc group expressed satisfaction with their treatment and would have the same treatment again, compared with the fusion group (P < 0.05). The hospital stay was significantly shorter in the CHARITE artificial disc group (P < 0.05). The complication rate was similar between both groups.

CONCLUSIONS

This prospective, randomized, multicenter study demonstrated that quantitative clinical outcome measures following lumbar total disc replacement with the CHARITE artificial disc are at least equivalent to clinical outcomes with anterior lumbar interbody fusion. These results support earlier reports in the literature that total disc replacement with the CHARITE artificial disc is a safe and effective alternative to fusion for the surgical treatment of symptomatic disc degeneration in properly indicated patients. The CHARITE artificial disc group demonstrated statistically significant superiority in two major economic areas, a 1-day shorter hospitalization, and a lower rate of reoperations (5.4% compared with 9.1%). At 24 months, the investigational group had a significantly higher rate of satisfaction (73.7%) than the 53.1% rate of satisfaction in the control group (P = 0.0011). This prospective randomized multicenter study also demonstrated an increase in employment of 9.1% in the investigational group and 7.2% in the control group.

Prospective randomized study of the Charite artificial disc: data from two investigational centers

BACKGROUND CONTEXT

For decades there has been a desire to restore motion of a painful degenerated spinal segment. Artificial discs have been used in Europe for almost 20 years. In the few reports available in the literature, the results have been promising. However, there have been no prospective randomized studies comparing artificial discs with spinal fusion.

PURPOSE

The purpose of this study was to determine if patients with symptomatic degenerative disc disease treated with Charite artificial disc (DePuy Spine, Raynham, MA) arthroplasty would show significant improvement in functional outcome measures and to compare these results to fusion.

STUDY DESIGN/SETTING

This was a prospective randomized clinical trial comparing total disc replacement with anterior lumbar interbody fusion using cages. The data reported were collected from two spine specialty centers participating in a Food and Drug Administration regulated trial.

METHODS

A consecutive series of 144 patients were randomized using a 2:1 ratio of Charite versus BAK (Zimmer Spine, Minneapolis, MN). All patients were being treated for single-level discogenic pain confirmed by plain radiography, magnetic resonance imaging and provocative discography. Data were collected at designated follow-up periods for up to 24 months.

RESULTS

The mean age was 40.1 years (range, 21 to 56 years). Forty-four cases had BAK anterior interbody fusion, and 100 cases were randomized to Charite disc replacement. The mean operating time was 76.2 minutes (range, 54 to 137 minutes) for the Charite cases. The mean estimated blood loss was 196.2 cc (range, 50 to 1,800 cc). Most patients were discharged in 1 to 2 days with a soft corset and returned to normal activities within 3 weeks if they underwent the disc replacement. The mean Oswestry Disability Index score for the BAK group was 69.6+/-12.8 preoperatively and 27.5+/-26.4 at 24-month follow-up (p<.001) The corresponding mean Oswestry score for the Charite disc patients was 70.9 preoperatively and 30.0 at 24-month follow-up (p<.001).

CONCLUSIONS

In this prospective randomized study, both surgical groups improved significantly. Complications of total disc replacement were similar to those encountered with anterior lumbar interbody fusion. Total disc replacement appears to be a viable alternative to fusion for the treatment of single-level symptomatic disc degeneration unresponsive to nonoperative management.