Mid- to long-term results of total lumbar disc replacement: a prospective analysis with 5- to 10-year follow-up

The Spine Journal

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(2013)

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Clinical Study

Mid- to long-term results of total lumbar disc replacement: a prospective analysis with 5- to 10-year follow-up Christoph J. Siepe, MD, PhDa,*, Franziska Heider, MDa, Karsten Wiechert, MDb, Wolfgang Hitzl, PhD, MScc, Basem Ishak, MDd, Michael H. Mayer, MD, PhDa a

Sch€ on Klinik Munich Harlaching, Spine Center, Academic Teaching Hospital of the Paracelsus Medical University Salzburg (AU), Harlachinger Str. 51, D-81547 Munich, Germany b Department of Spinal Surgery, Hessingpark Clinic, Hessingstrasse 17; D-86199 Augsburg, Germany c Paracelsus Medical University Salzburg, Biostatistics, Research Office, Strubergasse 21, 5020 Salzburg, Austria d Department of Neurosurgery, University of Heidelberg, Im Neuenheimer Feld 400, D-69120 Heidelberg, Germany Received 17 March 2013; revised 21 July 2013; accepted 22 August 2013

Abstract

BACKGROUND CONTEXT: The role of fusion of lumbar motion segments for the treatment of intractable low back pain (LBP) from degenerative disc disease (DDD) without deformities or instabilities remains controversially debated. Total lumbar disc replacement (TDR) has been used as an alternative in a highly selected patient cohort. However, the amount of long-term follow-up (FU) data on TDR is limited. In the United States, insurers have refused to reimburse surgeons for TDRs for fear of delayed complications, revisions, and unknown secondary costs, leading to a drastic decline in TDR numbers. PURPOSE: To assess the mid- and long-term clinical efficacy as well as patient safety of TDR in terms of perioperative complication and reoperation rates. STUDY DESIGN/SETTING: Prospective, single-center clinical investigation of TDR with ProDisc II (Synthes, Paoli, PA, USA) for the treatment of LBP from lumbar DDD that has proven unresponsive to conservative therapy. PATIENT SAMPLE: Patients with a minimum of 5-year FU after TDR, performed for the treatment of intractable and predominant ($80%) axial LBP resulting from DDD without any deformities or instabilities. OUTCOME MEASURES: Visual analog scale (VAS), Oswestry Disability Index (ODI), and patient satisfaction rates (three-scale outcome rating); complication and reoperation rates as well as elapsed time until revision surgery; patient’s professional activity/employment status. METHODS: Clinical outcome scores were acquired within the framework of an ongoing prospective clinical trial. Patients were examined preoperatively, 3, 6, and 12 months postoperatively, annually from then onward. The data acquisition was performed by members of the clinic’s spine unit including medical staff, research assistants, and research nurses who were not involved in the process of pre- or postoperative decision-making. RESULTS: The initial cohort consisted of 201 patients; 181 patients were available for final FU, resembling a 90.0% FU rate after a mean FU of 7.4 years (range 5.0–10.8 years). The overall results revealed a highly significant improvement from baseline VAS and ODI levels at all postoperative FU stages (p!.0001). VAS scores demonstrated a slight (from VAS 2.6 to 3.3) but statistically significant deterioration from 48 months onward (p!.05). Patient satisfaction rates remained stable throughout the entire postoperative course, with 63.6% of patients reporting a highly satisfactory

FDA device/drug status: Approved (Pro DiscII (Synthes, Paoli, PA)). Author disclosures: CJS: Consulting: Synthes; Speaking and/or Teaching Arrangements: Synthes (C); Trips/Travel: Synthes (C); Research Support (Investigator Salary, Staff/Materials): Synthes (C). FH: Nothing to disclose. KW: Nothing to disclose. WH: Fees for participation in review activities such as data monitoring boards, statistical analysis, end point committees, and the like: Paracelsus Medical University Salzburg, Austria, Research Office (statistical analysis) (A, Paid directly to institution). BI: Nothing to disclose. MHM: Consulting: Synthes, Paoli, PA (E); Speaking 1529-9430/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.spinee.2013.08.028

and/or Teaching Arrangements: Synthes, Paoli, PA (E); Trips/Travel: Synthes, Paoli, PA (E). The disclosure key can be found on the Table of Contents and at www. TheSpineJournalOnline.com. * Corresponding author. Head of Department, Spine Center, Sch€on Klinik Munich Harlaching, Academic Teaching Hospital of the Paracelsus Medical University Salzburg (AU), Harlachinger Str. 51, D-81547 Munich, Germany. Tel.: (49) 89-6211-0; fax: (49) 89-6211-2012. E-mail address: [email protected] (C.J. Siepe)

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C.J. Siepe et al. / The Spine Journal

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or a satisfactory (22.7%) outcome, whereas 13.7% of patients were not satisfied. The overall complication rate was 14.4% (N526/181). The incidence of revision surgeries for general and/or device-related complications was 7.2% (N513/181). Two-level TDRs demonstrated a significant improvement of VAS and ODI scores in comparison to baseline levels (p!.05). Nevertheless, the results were significantly inferior in comparison to one-level cases and were associated with higher complication (11.9% vs. 27.6%; p5.03) and inferior satisfaction rates (p!.003). CONCLUSIONS: Despite the fact that the current data comprises the early experiences and learning curve associated with a new surgical technique, the results demonstrate satisfactory and maintained mid- to long-term clinical results after a mean FU of 7.4 years. Patient safety was proven with acceptable complication and reoperation rates. Fear of excessive late complications or reoperations following the primary TDR procedure cannot be substantiated with the present data. In carefully selected cases, TDR can be considered a viable treatment alternative to lumbar fusion for which spine communities around the world seem to have accepted mediocre clinical results as well as obvious and significant drawbacks. Ó 2013 Elsevier Inc. All rights reserved. Keywords:

Disc replacement; Arthroplasty; Artificial disc; Lumbar spine; Long term results; Outcome; Complications

Introduction

Materials and methods

Fusion of lumbar motion segments performed for the treatment of intractable low back pain (LBP) from degenerative disc disease (DDD) without any deformities or instabilities are associated with a variety of negative side effects, including adjacent level pathologies, considerable complication and reoperation rates, symptomatic facet and sacroiliac joint complaints, cranial facet joint violations, adjacent segment stenosis, negatively altered sagittal alignment, pseudarthrosis, graft site morbidity, and others [1–13]. In an attempt to avoid these fusion-related negative side effects, motion-preserving technologies such as total lumbar disc replacement (TDR) have been introduced. Approximately 3 decades after the initial introduction of the SB Charite disc (DePuy, Raynham, MA, USA), a substantial amount of class I to class IV data has been published, the majority of which reported satisfactory clinical results. The data from prospective randomized controlled clinical trials confirmed at least noninferiority or even superiority in comparison to varying control cohorts using fusion procedures [14–22]. Despite these previously published evidence-based data, a variety of authors, surgeons, regulatory institutions, and health care insurers as well as health care providers have reported controversial and at times have displayed irrational perceptions related to TDR, including fears of deteriorating results as well as excessive late complications and revision surgeries [23–32]. To assess the role of any new treatment method, longterm clinical results need to be evaluated in clinical studies with adequately sized patient cohorts and sufficient mid- to long-term results. To date, the number of previously published long-term follow-up (FU) studies on TDR is scarce. The aim of the current study was therefore to evaluate the mid and long-term clinical results as well as patient safety in terms of complications and revision surgeries in a cohort of TDR patients.

Preoperative diagnosis and patient selection All patients included in this study are part of an ongoing prospective clinical trial with ProDisc II (Synthes, Paoli, PA, USA). The minimum FU required for inclusion in this study was 5 years. Disc replacement was performed for the treatment of patients with predominant ($80%) axial LBP originating from lumbar DDD. Indications and contraindications for this procedure have been thoroughly outlined previously [15,17,33–37]. Radiculopathy was considered a clear contraindication against TDR. Patients with a history of previous revision surgery as well as patients with combined fusion and TDR procedures were excluded from participation in this study. A summary of exclusion criteria from this study is listed in Table 1. All patients were nonresponders to an intensive inpatient and outpatient conservative treatment program conducted over a minimum 6-month period. The preoperative diagnosis was made on the basis of lumbar radiographs taken in anteroposterior and lateral views, functional flexion/extension images, and preoperative magnetic resonance imaging of the lumbar spine. Patients with previous discectomies were excluded if they had significant leg pain, if Gadolinium-DTPA magnetic resonance imaging revealed any notable scar tissue formation in the spinal canal and/or morphological alterations of the facet joints. Preoperatively, all patients underwent fluoroscopically guided spine infiltrations to rule out nondiscogenic pain sources. Patients who demonstrated significant and reproducible pain relief ($50%) following infiltrations of the facet or the sacroiliac joints were not considered candidates for TDR because a discogenic origin of pain was less likely and nonsurgical treatment was the preferred treatment option. The role of discography in identifying discogenic pain remains debatable. Previous studies showed an equally high

C.J. Siepe et al. / The Spine Journal Table 1 Exclusion criteria/contraindications -

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Central or lateral spinal stenosis Predominant radiculopathy Facet joint arthrosis/symptomatic facet joint complaints Spondylolysis/spondylolisthesis Spinal instability (iatrogenic/altered posterior elements; eg, following laminectomy) Major deformity/curvature deviations (eg, scoliosis) Metabolic bone disease (eg, manifest osteoporosis/osteopenia) Previous operation with severe scarring and radiculopathy Compromised vertebral body (irregular end plate shape) Previous/latent infection Metal allergy Spinal tumor Posttraumatic segments

rate of false-positive and false-negative results [38], failure of the patient to distinguish between concordant and nonconcordant pain [39], 100% memory pain in patients with abnormal psychometric testing [39], and 0.5% infection rate [39,40]. Furthermore, studies have shown that the degenerative process within a disc can be initiated with a mere needle puncture (ie, that performed during lumbar discography) [41–50]. A recent study has demonstrated pressure increases in adjacent level discs during lumbar discography, which similarly led the authors to the conclusion to question the method’s validity [51]. Therefore, discography was not used as a diagnostic tool in the present study. Women older than 45 and men older than 55 received routine dual radiograph absorptiometry scans for bone density measurements. In accordance with the World Health Organization definition of osteopenia, patients with a T-score exceeding
1.0 were not considered candidates for TDR. Disc spaces were approached through a mini–open laparotomy and a retroperitoneal approach as described previously [52,53]. Insertion of the ProDisc implant was performed according to the manufacturer’s guidelines [54]. Study documentation All data were recorded within the framework of an ongoing prospective clinical trial. Patients were examined preoperatively, followed by routine clinical and radiological examinations at 3, 6, and 12 months postoperatively, annually from then onward. Study documentation was standardized and included the Visual analog scale (VAS), Oswestry Disability Index (ODI) [55], and numerous clinical and radiological parameters. The patient’s subjective outcome evaluation was based on a three-scale grading system: highly satisfied, satisfied, and not satisfied. The clinical data acquisition was performed by members of the clinic’s spine unit, including medical staff, research assistants, and research nurses. Medical staff members who were involved in the data acquisition were members of the spine unit who were not involved in the process of pre- or postoperative decision-making.

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Data on complications and reoperations were reported by the surgeons. The peri- and postoperative course of all surgeries was further controlled independently and prospectively by two members of the spine unit who followed all surgeries and surgical protocols and who specifically searched the procedures for any kind of critical event that had occurred. All complications and reoperations were documented accordingly. Industry relationship/conflict of interest The data acquisition and evaluation of the current study were fully independent of any type of industry support or remuneration. No direct or indirect funding was received by the authors or the institution in support of this study. The research was undertaken as part of the clinics and spine unit’s internal quality reviewing process and its execution was therefore subsidized in its entirety by the clinic’s internal resources. The data acquisition, including clinical data and the documentation of complication and reoperation rates, was exclusively performed by members of the clinics spine unit, including members of the medical staff, research assistants, and research nurses. Assistance received by national and international fellows as well as doctorate students similarly did not receive any type of reimbursement. Medical staff members who were involved in the data acquisition were members of the spine unit who were not involved in the process of pre- or postoperative decisionmaking. The company/manufacturer had no access to or influence on the data whatsoever. The authors were the sole custodians of the data at all times. Statistical analysis All data were statistically evaluated by an external, independent statistician not involved in the process of pre- or postoperative decision-making (WH). ODI and VAS values were tested for normality based on the KolmogorovSmirnov test. The data were carefully checked for possible outliers. For descriptive analyses, means and standard deviations were computed. Two-sided paired and unpaired Student t tests and Welch analysis of variance were used to compare means among several groups. A 95% confidence interval (CI) for means and difference of means was computed. Whisker plots were used to illustrate results. Fisher’s exact test was used to analyze 22 cross-tabulation tables; the Kruskal-Wallis test for singly ordered crosstabulation tables was used to test 23 tables. Pearson-Clopper confidence intervals were computed for the complication rates. A p value less than 5% was used to indicate a statistically significant difference. All analyses were done using STATISTICA 10 data analysis software system (StatSoft Inc., 2011 Tulsa, OK, USA) and StatXact (Cytel Software Corporation (2002) StatXact 6.0, Cytel Software Corporation, Cambridge MA, USA) [56].

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Fig. 1. Mean pre- and postoperative visual analog scale (VAS) (Top) and Oswestry Disability Index scores (ODI) (Bottom) for the entire study cohort of 181 patients after a mean follow-up period of 7.4 years (88.3 months). Both VAS and ODI scores demonstrated a significant improvement in comparison to baseline levels (p!.001). Although ODI scores remained stable, VAS scores demonstrated a deterioration from 48 months’ postoperatively onwards (p!.05). CI, confidence interval.

Results Study population and cohort definition A total of 201 patients were included in the study, of which N520 patients were lost to FU. Thus, the final study cohort consisted of 181 patients, which reflects an overall FU rate of 90.0% (N5181/201). The mean follow-up was 7.4 years (88.3 months), ranging from 5.0 to 10.8 years (60.4–129.6 months). N570 patients were male (38.7%); N5111 were female (61.3%). The average age was 43.0 years (range 21.9–66.1 years). The majority of disc replacements were performed as single-level procedures (N5151, 83.4%) at the levels L4– L5 (N530, 16.6%), L5–S1 (N5111, 61.3%), L5–L6

(N56; 3.3%), L2–L3 (N51; 0.6%), L3–L4 (N51; 0.6%), and L4–S1 (N52; 1.1%). Twenty-nine TDRs (16.0%) were performed bisegmentally at the levels L4–S1 (N525; 13.8%), L3–L5 (N53; 1.7%), and L5–L6–S1 (N51; 0.6%). In one patient (0.6%), TDR was performed at three contiguous levels from L3 to S1. Indications for disc replacement included DDD with (N569, 38.1%) and without Modic changes (N554, 29.8%) without any other accompanying pathologies. TDR was performed in N515 patients (8.3%) with DDD and an accompanying contained, central to mediolateral disc herniation with clinically predominant axial low back pain ($80%). In N543 patients (23.8%), disc replacement was performed for the treatment of DDD following

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Forty-two percent of all patients returned to their former working environment full time without restrictions, whereas 8.6% returned to their previous work environment on a part-time basis but in a limited capacity. A total of 16.6% of the patients had reorganized their professional life and found themselves in a new working environment. A total of 14.4% of the patients received workers compensation, 8.8% received a pension, and 6.6% of the patients were

(112) (40) (22) (152/174) 63.6 22.7 13.7 86.3 — — — — (34) (11) (4) (45/49) 69.4 22.4 8.2 91.8 (57) (17) (9) (74/83) 68.7 20.5 10.8 89.2 (43) (18) (8) (61/69) 62.3 26.1 11.6 89.7 (67) (24) (22) (91/113) 59.3 21.2 19.5 74.5 (74) (27) (21) (101/122) 60.7 22.1 17.2 82.8 (65) (32) (23) (97/120) 54.2 26.7 19.2 80.8 (78) (45) (22) (123/145) 53.4 30.8 15.1 84.8 — — — —

181 20.3619.3 3.362.8 55 21.6615.0 3.262.2 55 20.1619.3 3.262.9 43 18.2618.0 3.262.6 55 18.3618.2 3.262.7 121 18.9619.5 2.962.8 114 19.3619.7 2.862.8 113 18.3617.1 2.662.4 134 21.7617.6 3.062.5

96 Mo 72 Mo 48 Mo 24 Mo 12 Mo

Mean values6standard deviation are provided. From the 24-month FU onward, the results are delineated in biannual time intervals.

Professional activity

6 Mo

As outlined in Table 2, 63.6% of all patients were highly satisfied with their subjective outcome of the operation at the last FU examination, 22.7% were satisfied, and 13.7% of all patients reported an unsatisfactory outcome. Thus, the overall proportion of patients that reported to have either a satisfactory or a highly satisfactory outcome amounted to 86.3%. When asked retrospectively at the last FU examination, the majority of all patients (79.3%; N5134/169) reported they would be willing to undergo surgery again, 13.0% (N522/169) were unsure, and 7.7% (N513/169) declared they would refuse surgery.

3 Mo

Subjective outcome evaluation

Table 2 Overall results for the entire study cohort of 181 patients after an average follow-up of 7.4 years

Analysis of the clinical parameters from the entire study cohort showed a highly significant improvement of VAS and ODI scores at all FU stages in comparison to baseline levels (p!.001; Fig. 1, Top and Bottom). After correlating the clinical data from the early postoperative period, which was defined as FU between 3 and 12 months postoperatively, with the clinical outcome parameters from the mid- and long-term FU examinations ($24 months’ FU), the analysis demonstrated stable results throughout all stages of the postoperative course for ODI parameters without any statistically significant difference between early and late results (pO.05). Similarly, the patient’s subjective outcome evaluation of the operation was maintained throughout the entire postoperative course (Table 2). Analysis of VAS scores between the early-, mid-, and long-term FU stages demonstrated statistically significant inferior results from the 48-month FU evaluation onward (p!.05; Fig. 1, Top). Nevertheless, further analysis revealed that this statistically significant difference in clinical terms reflected a deterioration of only 0.66 points on the VAS scale from a mean VAS score of 2.6 (early FU) to 3.3 at the mid- and late FU stages (95% CI for deterioration: 0.01–1.18). Finally, VAS scores still demonstrated a highly significant improvement in comparison to preoperative pain levels at all postoperative FU stages (p!.0001).

120 Mo

Clinical results

181 42.5614.5 7.161.4

Results at last follow-up

a previous minimally invasive discectomy, either microsurgically or via a full endoscopic approach.

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Number of patients (N) Oswestry Disability Index (%) Visual analog scale Subjective satisfaction rates Highly satisfied, % (n) Satisfied, % (n) Not satisfied, % (n) Satisfiedþhighly Satisfied, % (n)

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Preoperative data

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Clinical Outcome Data

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Table 3 Peri- and postoperative complications following TDR in N5181 patients Intra-/perioperative complications General DVTþPEþlysis Superficial wound healing impaired with subcutaneous hematoma Hematoma of abdominal wall Retroperitoneal hematoma Retroperitoneal lymphocele Surgery- or access-related Retrograde ejaculation Postsympathectomy syndrome Plexus hypogastricus superior lesion with sexual dysfunction Persisting retroperitoneal secretion of unknown origin (2,000 mL) Technique-related Primary suboptimal implant placement Intraoperative posterior wall fracture and posterior fragment dislocation Postoperative complications General complications Adjacent level disc herniation Index segment spinal stenosis Specific complications Implant subsidence Postoperative neuropathy L5 Inlay dislocation and subluxation of prosthesis CVA with bilateral isthmus stress fracture and subluxation of TDR Bilateral isthmus stress fracture Implant dislocation following fall 2 weeks postoperatively Split fracture L4 following TDR at L4–L5 Overall complication rate

N

%

Comment/treatment

1 1 1 1 1

0.6 0.6 0.6 0.6 0.6

Patient with known coagulopathy Revision surgery Revision surgery Revision laparotomy Revision surgery

4 4 1 1

2.2 2.2 0.6 0.6

5.7% of male patients affected; 2 persisting

Conservative therapy

1 1

0.6 0.6

Posterior instrumentation Posterior instrumentation with fragment removal and CSF leakage

3

1.7

1

0.6

1 case of postoperative discectomy followed by discitis, requiring adjacent level fusion Requiring microsurgical decompression

2 1

1.1 0.6

2 1

1.1 0.6

1 1 1 26

0.6 0.6 0.6 14.4

Posterior fusion and cement augmentation Microsurgical decompression of neuroforamen L5–S1 and neurolysis L5 Anterior revision and implant replacement Anterior revision, implant removal, ALIF, and 360  fusion Posterior instrumentation Posterior instrumentation Conservative therapy

ALIF, anterior lumbar interbody fusion; CSF, cerebrospinal fluid; CVA, car vehicle accident; DVT, deep vein thrombosis; PE, pulmonary embolism; TDR, total lumbar disc replacement.

recorded as unemployed because of economic reasons. Thus, the overall rate of patients resuming some type of professional activity represented 66.9%. Complications An overview of all complications that were encountered in the current study is provided in Table 3. The overall complication rate was 14.4% (N526/181, 95% CI: 9.6–20.4%). It was 11.9% (N518/151, 95% CI: 7.2–18.2%) for monosegmental TDRs and 27.6% (N58/29, 95% CI: 12.7–47%) for bisegmental interventions, respectively. This difference between both complication rates was statistically significant (95% CI: 2.9–35.6%, Fisher’s exact test p5.031). Reoperations As outlined in Table 4, the overall reoperation rate was 16.0% (N529/181 cases). These reoperations can be subdivided into four subgroups: reoperations that resulted from immediate device- or technique related–complications (N59/ 181; 5.0%), reoperations that were general surgery–related (N54/181; 2.2%), reoperations for the treatment of persisting symptoms of LBP (N510/181; 5.5%), and finally a smaller

subgroup in which reoperation was indicated for the treatment of adjacent segment pathologies (N54; 2.2%). Thus, the overall incidence either general surgery– or device-related complications amounted to 7.2% (N513/181). Anterior revision surgery Anterior abdominal revision surgeries were necessitated in only 2.2% of all TDR candidates (N54/181 patients). These were performed during the early postoperative stage within 10–14 days following the initial TDR procedure because of a postoperative lymphocele in one case and a retroperitoneal hematoma in another (N52 cases, 1.1%). Potentially challenging and complicating late anterior revision surgery was required in two cases (1.1%). An anterior extrusion of the polyethylene inlay and secondary subluxation of the implant at the level L5–S1 was treated via an anterior approach and prosthesis replacement. As outlined previously, another patient had to undergo revision anteriorly as a result of a traumatic bilateral isthmus fracture and subluxation of the implant with implant removal, anterior lumbar interbody fusion, and posterior stabilization. All 4 cases of anterior revision surgeries were performed without any major intra or postoperative complications.

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Table 4 Summary of reoperations and revision surgeries following total lumbar disc replacement Intra-/perioperative Complications

N

%

Comment/treatment

Revision for general surgery–related complications

4

2.2

Revision surgery for device- or implant-related complications Inlay dislocation and prosthesis subluxation

9 2

5.0 1.1

2 1

1.1 0.6

1 1

0.6 0.6

1 1 10 1

0.6 0.6 5.5 0.6

Posterior instrumentation Posterior instrumentation

1 8 4 3

0.6 5.0 2.2 1.7

Interspinous spacer (Coflex) Treated with posterior instrumented and posterolateral fusion

1

0.6

Treated with microsurgical discectomy. One case followed by discitis necessitating fusion Adjacent level instrumented fusion

1 1

0.6 0.6

Treated with microsurgical decompression Anterior revision, implant removal, ALIF and 360  fusion

29

16.0

Implant subsidence Postoperative neuropathy L5 Primary suboptimal implant placement Intraoperative posterior wall fracture and posterior fragment dislocation Implant dislocation following fall 2 weeks postoperatively Bilateral isthmus stress fracture Overall revision surgery for persisting LBP Postoperative index level hyperlordosis with facet joint complaints Postoperative facet joint complaints Postoperative complaints unresponsive to conservative treatment Overall adjacent level reoperation Adjacent level disc herniation Symptomatic adjacent level disc degeneration Miscellaneous/unrelated to surgery/others Index level spinal stenosis CVA with bilateral isthmus stress fracture and subluxation of TDR Overall reoperation rate

1 1 1 1

retroperitoneal hematoma retroperitoneal lymphocele hematoma of the abdominal wall superficially impaired wound healing

1 treated with anterior revision surgery and implant replacement, 1 treated with posterior instrumentation Posterior instrumented fusion Microsurgical decompression of neuroforamen L5/S1 and neurolysis L5 Posterior instrumentation Posterior instrumentation with fragment removal and CSF leakage

Posterior dynamic fusion with Dynesis

ALIF, anterior lumbar interbody fusion; CSF, cerebrospinal fluid; CVA, car vehicle accident; TDR, total lumbar disc replacement.

Adjacent level reoperation The rate of reoperations for adjacent-level pathologies encountered after a mean FU of 7.4 years was 2.2% (N54/181; Table 4). Of those, one patient received an instrumented fusion for symptomatic adjacent level disc degeneration. Three patients received an adjacent level microsurgical discectomy, of which one patient developed discitis at the operated level that necessitated a 360 anterior revision and debridement with anterior lumbar interbody fusion and posterior instrumentation. Timing of reoperations Revision surgeries that were performed for either general surgery–, implant-, or device-related complications were performed early postoperatively after a mean FU of 0.2 months (range 0.07–0.4; 95% CI 0.0–0.5) and 13.3 months (range 0.1–55.1; 95% CI 2.5–27 months), respectively. The combined data of reoperations for both surgeryand device-related complications revealed a mean delay of 9.3 months following the index procedure (range 0.1–55; 95% CI 0.0–18.8). Revision surgeries for persisting LBP were performed after a mean FU of 43.2 months (range 10.8–98 months; 95% CI 17.3–69). Finally, surgeries for the treatment of

adjacent level pathologies were performed late postoperatively after 72.3 months (range 20–93.7; 95% CI 16.7–128). Mono versus bisegmental TDRs A comparison of pre- and postoperative VAS and ODI scores between mono- and bisegmental disc replacement procedures is outlined in Fig. 2, Top and Bottom. There was no significant difference for VAS scores between both groups preoperatively (pO.05). Preoperative ODI scores, however, were significantly higher in the cohort with two-level pathologies (p!.05). Postoperatively, both VAS and ODI scores were significantly higher for two-level cases in comparison with monosegmental TDRs, reflecting inferior outcome and higher pain levels during the postoperative stage (p!.05). Nevertheless, all two-level TDRs revealed postoperative VAS and ODI scores that were still significantly lower at all postoperative stages in comparison to preoperative pain levels, respectively (p!.05). At each patient’s last FU examination, 67.3% (N599/ 147) of all patients with one-level TDR reported a highly satisfactory outcome, 21.8% (N532/147) reported a satisfactory outcome, and 10.9% (N516/147) of all patients were not satisfied with the outcome of their operation.

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Conversely, for all two-level cases, the satisfaction rates of patients that were highly satisfied dropped to 41.4% (N512/29), 27.6% (N58) reporting a satisfactory outcome, and those reporting an unsatisfactory outcome increased to 31.0% (N59/29 patients). The difference in patient satisfaction rates that was observed between mono- and bisegmental TDR procedures was statistically significant (Kruskal-Wallis test for crosstabulation tables, p!.003). Discussion Much attention has been drawn to the technique of TDR for the treatment of symptomatic lumbar DDD that has been unresponsive to conservative treatment as an alternative to lumbar fusion. The search for alternatives to lumbar

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fusion procedures can be attributed to a variety of perceived negative side effects, including adjacent level pathologies, considerable complication and reoperation rates, symptomatic facet and sacroiliac joint complaints, cranial facet joint violations, adjacent segment stenosis, negatively altered sagittal alignment, pseudarthrosis, graft site morbidity, and others [1–13]. To assess the value of motion-preserving technologies, the accumulation and analysis of long-term data are paramount. Thus, one of the aims of the current study was to analyze the long-term efficacy of TDR from a single spine center that, as part of what initially began as a multicenter investigational trial, was one of Europe’s first centers to establish and incorporate TDR with ProDisc II into its clinical practice.

Fig. 2. Comparison of pre- and postoperative visual analog scale (VAS) (Top) and Oswestry Disability Index (ODI) (Bottom) scores of total lumbar disc replacement (TDR) between mono- and bisegmental interventions. Preoperative ODI scores were significantly higher in the cohort of two-level TDRs (p!.05). Postoperatively, VAS and ODI score were significantly higher for two-level in comparison to one-level cases (p!.05), which nevertheless demonstrated significant improvements in comparison to preoperative pain levels (p!.05).

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The current data were acquired within the framework of an uncontrolled prospective case series (class IV data) from a large single spine center. Advantages and drawbacks of this type of study setting have previously been extensively outlined. Furthermore, the potential for bias has previously been reported for industry-funded studies with greater likelihood to report positive results than for studies with other funding sources [57]. It is therefore important to highlight the complete financial independence of the current study as outlined in the ‘‘Materials and methods’’ section. This research project was undertaken as part of the clinics and spine unit’s internal quality reviewing process and its execution was therefore subsidized in its entirety by the clinic’s internal resources. To date, the data from this article represent the largest series of patients with long-term FU after TDR (Table 5). Clinical results The data from this study reveal satisfactory clinical results throughout the entire postoperative course over a FU period ranging from 5.0 to 10.8 years. Patient satisfaction rates and ODI scores remained stable (Fig. 1, Top and Bottom, Table 2). VAS and ODI scores were well below preoperative baseline levels at all postoperative stages, respectively (p!.001). VAS scores revealed a slight deterioration, which was tested to be statistically significant (p!.05). With all other outcome parameters remaining stable, however, the extent of deterioration of 0.66 point on the VAS scale from VAS 2.6 to 3.3 after a mean FU of 7.4 years is well below any threshold level that has been published to be of clinical relevance for the patient [58–62]. Finally, the number of patients that were considered to be dissatisfied with their subjective outcome (13.7%; Table 2) as well as the number of patients that reported they would, retrospectively, not opt for surgery again (7.7%), compares favorably with the data that have previously been published for lumbar fusion procedures. Learning curve Since the introduction of TDRs in the 1980s, extensive knowledge has been gained. Considerable progress with regard to the assessment of adequate indications and contraindications for TDR has been made [33–37,63–66], outcome-determining factors have been identified including the adequate extent of DDD, knowledge on the center of rotation, segmental and sagittal alignment after TDR, influence of pre- and postoperative mobility, and adequate implant placement [15,67–80]. Similarly, biomechanical and radiological studies have investigated the effect of TDR on the index and adjacent level as well as motion characteristics of the prosthesis and the lumbar spine to a large extent [81–101]. Despite the previously mentioned satisfactory results, which were observed in the present study, the current data

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nevertheless have to be interpreted as a ‘‘worst-case scenario’’ that included the initial clinical and technical learning curve. Thus, comparison of the data presented in the current manuscript should only carefully be applied and compared with any results that can be expected with today’s knowledge and expertise. Patient safety In the United States, insurers have refused to reimburse surgeons for TDRs for fear of delayed complications, revisions, and unknown secondary costs. Consequently, the number of TDR procedures has dropped significantly and is currently limited to a few expert centers across the United States. Outside of the United States, there is a marked misconception that the developments and the decline in US TDR numbers are based on medical reasoning. Consequently, one of the primary goals of this present study was to investigate the patient’s safety in terms of complication and reoperation rates. Previously published studies have reported widely diverging complication rates following TDR, the majority of which ranged between 10% and 20% [15,16,71,77,102–107]. The data in this article reveal an acceptable overall complication rate of 14.4%. These numbers should similarly be compared with the data that have been previously published on lumbar fusion procedures, which have reported considerably higher complication rates [108,109]. The reoperation rates that were encountered in the present study can be categorized into those resulting from general surgery–related complications (N54, 2.2%), those for implant- or device-related complications (N59, 5.0%), and those that were required for the treatment of adjacent-level pathologies (N54, 2.2%). Thus, the overall reoperation rate that resulted from any immediate surgery or implant- or device-related complication amounted to 7.2%. These numbers should similarly be taken into consideration when comparing TDR with any type of fusion procedure for which cumulative reoperation rates ranging between 18% to 35% have been reported [109–111]. Several patients that required reoperations in the present cohort were treated for persisting LBP (N510; 5.5%). This patient cohort should, however, be strictly separated from the revision surgeries that were outlined previously because this number does not reflect any detrimental impact on the patient’s safety or any type of surgery- or device-related complications. Similar experiences have been reported from US Food and Drug Administration (FDA) investigational device exemption (IDE) study, class 1 data. Zigler et al. reported a 7.9% reoperation rate in 1,000 patients treated at a single spine center (2 access surgeons, 11 spine surgeons) after a mean FU of 54.4 months (range 18–117 months) [112]. The majority of revision surgeries were performed for persisting back pain, fewer were performed for implant failures. Comparable to our data, the authors reported a rate of

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Table 5 Previously published long-term results following TDR Park et al. [130]

David et al. [126]

Tropiano et al. [128]

Lemaire et al. [106]

Putzier et al. [132] Guyer et al. [18]

Scott-Young [132]

ProDisc II

ProDisc II

Charite III

ProDisc I

Charite III

Charite I – III

Charite

Charite

Original study cohort (no. of patients) Final cohort (no. of patients) Follow-up rate

201

42

108

64

107

71

90

122

181

35

106

55

100

53

90

NA

74.6%

Mean follow-up (range) Study design

7.4 yr (5.0–10.8 yr)

6 yr (5–7.8 yr)

13.2 yr (10–16.8 yr)

8.7 yr (7.1–10.7 yr)

11.3 yr (10–13.4 yr)

57% of eligible NA randomized patients; 44% of the total IDE patient cohort 5 yr (range NA) 3.7 yr (2–10 yr)

Prospective Single center Nonrandomized

Retrospective Single center Nonrandomized

Retrospective Single center Nonrandomized

Prospective Single center Nonrandomized

Retrospective Single center Nonrandomized

90.0%

83.3%

98.1%

86%

93.5%

17.3 yr (14.5–19.2 yr) Retrospective Single center Nonrandomized

No. of disc replacements

122 All single level

22

9.0

7.7

3.3

1.1

0

-

47 males (52.2%); 64 males (52.5%); 58 43 females females (47.5%). (47.8%). 40.5 yr (19–60 yr) 43.9 yr (20–67 yr) 57.8 85 Clinical success as Excellent or good results according to defined by FDA (nonvalidated patient satisfaction and activity level clinical scale)

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FDA, US Food and Drug Administration; IDE, Investigation Device Exemption Study; NA, not available; TDR, total lumbar disc replacement.

Prospective Single center Nonrandomized

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212 51 108 78 147 84 151 one-level, 33 one-level, 9 All single level 35 one-level, 17 54 1-level, 45 74 1-level, 29 two-level, 1 two-level two-level, 3 2-level, 1 3-level 10 2-level three-level TDR three-level Gender 70 male (38.7%); 111 19 males (54.3%); 16 45 males (41.7%); 63 30 males (54.5%); 25 41 males (41%); 59 20 males (37.7%); female (61.3%). females (45.7%). females (58.3%). females (45.5%). females (59%). 33 females (62.3%). Average age (range) 43.0 yr (21.9–66.1 yr) 46 yr (27–70 yr) 36.4 yr (23–50 yr) 46 yr (25–65 yr) 39.6 yr (23.9–50.8 yr) 44 yr (30–59 yr) Success rate (%) 86.3 71.4 82.1 75 90 54 Excellent or Definition of Subjective patient In accordance with Excellent or good Excellent or good Excellent or good clinical outcome as clinical outcome as good results success criteria outcome evaluation multiple FDA clinical outcome as according to rated by modified rated by modified (highly satisfied, clinical success rated by modified Odom’s criteria criteria Stauffer-Coventry Stauffer-Coventry Stauffer-Coventry satisfied, not scale scale (including satisfied) (nonvalidated scale clinical scale) return to work) Overall complication 14.4 0 22.2 9 9 NA rate (%) Reoperation rate (%) 7.2 for implant- or NA 10.4 NA 6 11 device-related complications; 16.0 overall Adjacent-level (2.2 reoperation rate No radiographic 2.8 NA 2 17 disease (%) for adjacent-level parameters pathologies)

Prospective Multicenter Randomized controlled FDA IDE 90 All single level

C.J. Siepe et al. / The Spine Journal

Current study Implant

C.J. Siepe et al. / The Spine Journal

anterior revision surgery of only 1.3%. Blumenthal et al., in another FDA IDE study trial comparing TDR with Charite III with anterior fusion, reported significantly lower reoperation rates in the cohort of TDR candidates (5.4% vs. 9.1%) [17]. McAfee et al., in another FDA IDE trial, reported an 8.8% reoperation rate in 589 patients, with a mean time to reoperation of 9.7 months [113]. Similar to the results observed by McAfee et al., a subsequent analysis of the timing of reoperations in our study delineated that the fear of secondary ‘‘uncontrolled numbers of revisions following TDR’’ at later FU stages cannot be substantiated with our data. The revision surgeries that occurred were predominantly located within the early postoperative stage after a mean of 9.3 months following the index procedure, whereas the number of any surgery or implantand device-related revisions at later stages was negligible. Mono- versus bisegmental TDRs The effect of multilevel disc replacements on the postoperative outcome has been discussed controversially. Although some authors described high success rates or even additive beneficial effects in multilevel TDR cases [64,114,115], others did not detect any negative impact on the postoperative outcome [104,116–118]—whereas still other study groups reported increasing complication rates, deteriorating results, and inferior biomechanics for multilevel disc replacements [34,86,92,116,119–122]. The data from the present study demonstrated significant VAS and ODI improvements for both one- and two-level procedures (p!.05; Fig 2, Top and Bottom). Nevertheless, significantly inferior outcome was observed for two-level TDRs in comparison to monosegmental interventions, which were furthermore associated with significantly inferior patient satisfaction rates and substantially higher complication rates (p!.05). Previous studies demonstrated inferior postoperative outcome in patients with higher baseline ODI scores [123]. However, the current findings can only partially be explained by higher ODI baseline levels that were encountered in the cohort of patients with two-level pathologies (p!.05). Despite these observations, similar findings of deteriorating results can be expected for other types of treatments (ie, for multilevel discectomies) or, likewise, when the outcome of multisegmental fusion procedures is compared with the outcome of a mere single-level treatment [124]. Because of the results that were encountered in the current study, however, the authors conclude that careful preoperative decision-making is paramount when attempting to achieve satisfactory results following TDR, particularly when indication for a two-level disc replacement is considered. Long-term FU data Several publications have reported on the efficacy of TDR worldwide [34,53,64,65,71,102,104,106,114,125–130],

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including results from prospective randomized controlled trials [14–22]. The data from the previously cited prospective randomized controlled clinical trials confirmed at least noninferiority or even superiority in comparison to the control cohorts. To date, the number of available studies that have reported on long-term outcome following TDR is limited (Table 5) [18,106,125,127,129,131,132]. Of those, the majority of studies confirm the data that were outlined in this article. From a medical and scientific point of view, it does not seem surprising that the most critical experiences were encountered in the study with the longest FU that has, to date, been published (mean 17.3 years, range 14.5–19.2 years) [131]. It is a general notion that nothing compromises outcome as much as a long-term FU, independent of the type of procedure being investigated, and it should be taken into consideration that much of the knowledge that has been accumulated over the past decades was not available for the majority of patients that received TDR in the 1980s. In this respect, a number of parallels can be drawn with the early failures and subsequent significant improvements of total hip replacements, which is a surgical treatment that has developed into one of the most successful interventions in the orthopedic surgeon’s armamentarium [29]. These facts should be kept in mind when addressing and discussing the content of long-term outcome data and to put the results of these studies into perspective adequately.

Conclusion An in-depth analysis and evaluation of any new surgical technique is of utmost importance in order to assess its role and value for today’s patient care. Topics to be addressed include mid- and long-term clinical results, patient safety, complication rates, the number and type of revision surgeries, and adequate indications and contraindications to this procedure. The data presented in this article reveal significant improvements and maintained clinical results for the overall study cohort in comparison to baseline pain levels, with acceptable complication and reoperation rates following lumbar TDR. Deteriorating results and higher complication rates observed in the cohort of two-level TDRs indicate that, to date, with currently available implant designs, the technique may have reached its limits and may not be a viable treatment option for multilevel pathologies. Much knowledge has been gained on TDR over the past decades. An extensive database on the clinical results is available from numerous randomized and nonrandomized clinical trials; complication and reoperation rates are known, revision strategies have been defined, outcome determining factors have been evaluated, and much knowledge has been gained from a large series of radiological and biomechanical studies on TDR.

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Disc replacement technologies have incited criticism for well-known negative side effects that, at the same time, seem to be widely accepted for lumbar fusion procedures by spine societies around the world. The data from this present study demonstrate that for a carefully selected cohort of patients, results compare favorably to the mediocre clinical results that have previously been published for a variety of different fusion techniques. Considering the large number of fusions being performed annually on a global scale, a relevant number of patients could, in fact, benefit from TDR as a viable treatment alternative.

Acknowledgments The authors of this study would like to thank Mrs. Pauline Jansen van Rensburg for the proof reading and editing of this article. The authors also would like to extend their gratitude to Mrs. Anita Luksa for essential patient data acquisition and research support. We wish to take this opportunity to express our appreciation to all the international fellows who contributed towards this ongoing prospective clinical trial over the years, namely Dr. Mohamed Khattab (Egypt), Dr. Carlos Sauri-Barraza (Mexico), Dr. Ajay Kumar (Malaysia) as well as Dr. Pjotr Zelenkov (Russia). We would like to thank our students, Dr. Elisabeth Haas and Dr. Alexander Tepass (Germany) from Paracelsus Private Medical University (PMU Salzburg, Austria), who completed their doctorate thesis on total lumbar disc replacement in our institution. References [1] Gillet P. The fate of the adjacent motion segments after lumbar fusion. J Spinal Disord Tech 2003;16:338–45. [2] Goulet JA, Senunas LE, DeSilva GL, et al. Autogenous iliac crest bone graft. Complications and functional assessment. Clin Orthop Relat Res 1997;76–81. [3] Kumar MN, Jacquot F, Hall H. Long-term follow-up of functional outcomes and radiographic changes at adjacent levels following lumbar spine fusion for degenerative disc disease. Eur Spine J 2001;10:309–13. [4] Lee CK. Accelerated degeneration of the segment adjacent to a lumbar fusion. Spine 1988;13:375–7. [5] Park P, Garton HJ, Gala VC, et al. Adjacent segment disease after lumbar or lumbosacral fusion: review of the literature. Spine 2004;29:1938–44. [6] Park Y, Ha JW, Lee YT, et al. Cranial facet joint violations by percutaneously placed pedicle screws adjacent to a minimally invasive lumbar spinal fusion. Spine J 2011;11:295–302. [7] Umehara S, Zindrick MR, Patwardhan AG, et al. The biomechanical effect of postoperative hypolordosis in instrumented lumbar fusion on instrumented and adjacent spinal segments. Spine 2000;25: 1617–24. [8] Katz V, Schofferman J, Reynolds J. The sacroiliac joint: a potential cause of pain after lumbar fusion to the sacrum. J Spinal Disord Tech 2003;16:96–9. [9] Maigne JY, Planchon CA. Sacroiliac joint pain after lumbar fusion. A study with anesthetic blocks. Eur Spine J 2005;14:654–8. [10] Ha KY, Lee JS, Kim KW. Degeneration of sacroiliac joint after instrumented lumbar or lumbosacral fusion: a prospective cohort study over five-year follow-up. Spine 2008;33:1192–8.

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[11] Moshirfar A, Jenis LG, Spector LR, et al. Computed tomography evaluation of superior-segment facet-joint violation after pedicle instrumentation of the lumbar spine with a midline surgical approach. Spine 2006;31:2624–9. [12] Shah RR, Mohammed S, Saifuddin A, et al. Radiologic evaluation of adjacent superior segment facet joint violation following transpedicular instrumentation of the lumbar spine. Spine 2003;28: 272–5. [13] Cardoso MJ, Dmitriev AE, Helgeson M, et al. Does superiorsegment facet violation or laminectomy destabilize the adjacent level in lumbar transpedicular fixation? An in vitro human cadaveric assessment. Spine 2008;33:2868–73. [14] McAfee PC, Cunningham B, Holsapple G, et al. A prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of lumbar total disc replacement with the CHARITE artificial disc versus lumbar fusion: part II: evaluation of radiographic outcomes and correlation of surgical technique accuracy with clinical outcomes. Spine 2005;30:1576–83; discussion E388–90. [15] Zigler J, Delamarter R, Spivak JM, et al. Results of the prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential fusion for the treatment of 1-level degenerative disc disease. Spine 2007;32:1155–62; discussion 1163. [16] Zigler JE. Clinical results with ProDisc: European experience and U.S. investigation device exemption study. Spine 2003;28:S163–6. [17] Blumenthal S, McAfee PC, Guyer RD, et al. 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. Spine 2005;30:1565–75; discussion E387–91. [18] Guyer RD, McAfee PC, Banco RJ, et al. Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of lumbar total disc replacement with the CHARITE artificial disc versus lumbar fusion: five-year follow-up. Spine J 2009;9:374–86. [19] Gornet MF, Burkus JK, Dryer RF, et al. Lumbar disc arthroplasty with MAVERICK disc versus Stand-Alone interbody fusion: a prospective, randomized, controlled, multicenter investigational device exemption trial. Spine 2011;36:E1600–11. [20] Delamarter R, Zigler JE, Balderston RA, et al. Prospective, randomized, multicenter Food and drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumferential arthrodesis for the treatment of two-level lumbar degenerative disc disease: results at twenty-four months. J Bone Joint Surg Am 2011;93:705–15. [21] Hochschuler SH, Ohnmeiss DD, Guyer RD, et al. Artificial disc: preliminary results of a prospective study in the United States. Eur Spine J 2002;11(2 Suppl):S106–10. [22] Sasso RC, Foulk DM, Hahn M. Prospective, randomized trial of metal-on-metal artificial lumbar disc replacement: initial results for treatment of discogenic pain. Spine 2008;33:123–31. [23] Whang PG, Simpson AK, Rechtine G, et al. Current trends in spinal arthroplasty: an assessment of surgeon practices and attitudes regarding cervical and lumbar disk replacement. J Spinal Disord Tech 2009;22:26–33. [24] Anderson PA, Rouleau JP. Intervertebral disc arthroplasty. Spine 2004;29:2779–86. [25] de Kleuver M, Oner FC, Jacobs WC. Total disc replacement for chronic low back pain: background and a systematic review of the literature. Eur Spine J 2003;12:108–16. [26] van Ooij A, Oner FC, Verbout AJ. Complications of artificial disc replacement: a report of 27 patients with the SB Charite disc. J Spinal Disord Tech 2003;16:369–83. [27] Pearcy MJ. Artificial lumbar intervertebral disc replacement: accepted practice or experimental surgery? Expert Rev Med Devices 2010;7:855–60.

C.J. Siepe et al. / The Spine Journal [28] Kurtz SM, Lau E, Ianuzzi A, et al. National revision burden for lumbar total disc replacement in the United States: Epidemiologic and Economic Perspectives. Spine 2010 Feb 26. [Epub ahead of print]. [29] Mayer HM, Siepe CJ. Prosthetic total disk replacement-can we learn from total hip replacement? Orthop Clin North Am 2011;42: 543–54. [30] Polly DW Jr. Adapting innovative motion-preserving technology to spinal surgical practice: what should we expect to happen? Spine 2003;28:S104–9. [31] Ross R, Mirza AH, Norris HE, et al. Survival and clinical outcome of SB Charite III disc replacement for back pain. J Bone Joint Surg Br 2007;89:785–9. [32] Singh K, Vaccaro AR, Albert TJ. Assessing the potential impact of total disc arthroplasty on surgeon practice patterns in North America. Spine J 2004;4:195S–201S. [33] Huang RC, Lim MR, Girardi FP, et al. The prevalence of contraindications to total disc replacement in a cohort of lumbar surgical patients. Spine 2004;29:2538–41. [34] Siepe CJ, Mayer HM, Wiechert K, et al. Clinical results of total lumbar disc replacement with ProDisc II: three-year results for different indications. Spine 2006;31:1923–32. [35] McAfee PC. The indications for lumbar and cervical disc replacement. Spine J 2004;4:177S–81S. [36] Wong DA, Annesser B, Birney T, et al. Incidence of contraindications to total disc arthroplasty: a retrospective review of 100 consecutive fusion patients with a specific analysis of facet arthrosis. Spine J 2007;7:5–11. [37] Chin KR. Epidemiology of indications and contraindications to total disc replacement in an academic practice. Spine J 2007;7: 392–8. [38] Carragee EJ, Tanner CM, Yang B, et al. False-positive findings on lumbar discography. Reliability of subjective concordance assessment during provocative disc injection. Spine 1999;24: 2542–7. [39] Carragee EJ, Chen Y, Tanner CM, et al. Can discography cause long-term back symptoms in previously asymptomatic subjects? Spine 2000;25:1803–8. [40] Block AR, Vanharanta H, Ohnmeiss DD, et al. Discographic pain report. Influence of psychological factors. Spine 1996;21:334–8. [41] Adams MA, Roughley PJ. What is intervertebral disc degeneration, and what causes it? Spine 2006;31:2151–61. [42] Berlemann U, Gries NC, Moore RJ. The relationship between height, shape and histological changes in early degeneration of the lower lumbar discs. Eur Spine J 1998;7:212–7. [43] Carragee EJ, Don AS, Hurwitz EL, et al. 2009 ISSLS Prize Winner: does discography cause accelerated progression of degeneration changes in the lumbar disc: a ten-year matched cohort study. Spine 2009;34:2338–45. [44] Fujiwara A, Lim TH, An HS, et al. The effect of disc degeneration and facet joint osteoarthritis on the segmental flexibility of the lumbar spine. Spine 2000;25:3036–44. [45] Fujiwara A, Tamai K, Yamato M, et al. The relationship between facet joint osteoarthritis and disc degeneration of the lumbar spine: an MRI study. Eur Spine J 1999;8:396–401. [46] Hsieh AH, Hwang D, Ryan DA, et al. Degenerative anular changes induced by puncture are associated with insufficiency of disc biomechanical function. Spine 2009;34:998–1005. [47] Korecki CL, Costi JJ, Iatridis JC. Needle puncture injury affects intervertebral disc mechanics and biology in an organ culture model. Spine 2008;33:235–41. [48] Masuda K, Aota Y, Muehleman C, et al. A novel rabbit model of mild, reproducible disc degeneration by an anulus needle puncture: correlation between the degree of disc injury and radiological and histological appearances of disc degeneration. Spine 2005;30:5–14. [49] Moore RJ, Crotti TN, Osti OL, et al. Osteoarthrosis of the facet joints resulting from anular rim lesions in sheep lumbar discs. Spine 1999;24:519–25.

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[50] Nassr A, Lee JY, Bashir RS, et al. Does incorrect level needle localization during anterior cervical discectomy and fusion lead to accelerated disc degeneration? Spine 2009;34:189–92. [51] Hebelka H, Nilsson A, Hansson T. Pressure increase in adjacent discs during clinical discography questions the methods validity. 40th annual meeting of the International Society for the Study of the Lumbar Spine (ISSLS); 2013; Scottsdale, AZ. [52] Mayer HM, Wiechert K. Microsurgical anterior approaches to the lumbar spine for interbody fusion and total disc replacement. Neurosurgery 2002;51:S159–65. [53] Mayer HM, Wiechert K, Korge A, et al. Minimally invasive total disc replacement: surgical technique and preliminary clinical results. Eur Spine J 2002;11(2 Suppl):S124–30. [54] Bertagnoli R, Marnay T, Mayer HM, eds. The ProDisc Book. Tuttlingen, Germany: Spine Solutions GmbH, 2003. [55] Fairbank JC, Couper J, Davies JB, et al. The Oswestry low back pain disability questionnaire. Physiotherapy 1980;66:271–3. [56] Hill T, Lewicki P, eds. Statistiks: methods and applications. Tulsa, OK: StatSoft Inc., 2007. [57] Shah RV, Albert TJ, Bruegel-Sanchez V, et al. Industry support and correlation to study outcome for papers published in spine. Spine 2005;30:1099–104; discussion 1105. [58] Copay AG, Glassman SD, Subach BR, et al. Minimum clinically important difference in lumbar spine surgery patients: a choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form 36, and Pain Scales. Spine J 2008;8:968–74. [59] Glassman SD, Copay AG, Berven SH, et al. Defining substantial clinical benefit following lumbar spine arthrodesis. J Bone Joint Surg Am 2008;90:1839–47. [60] Parker SL, Adogwa O, Mendenhall SK, et al. Determination of minimum clinically important difference (MCID) in pain, disability, and quality of life after revision fusion for symptomatic pseudoarthrosis. Spine J 2012;12:1122–8. [61] Parker SL, Mendenhall SK, Shau D, et al. Determination of minimum clinically important difference in pain, disability, and quality of life after extension of fusion for adjacent-segment disease. J Neurosurg Spine 2012;16:61–7. [62] Hagg O, Fritzell P, Nordwall A. The clinical importance of changes in outcome scores after treatment for chronic low back pain. Eur Spine J 2003;12:12–20. [63] Bertagnoli R. The treatment of disabling lumbar discogenic low back pain with total disc arthroplasty utilizing the ProDisc prosthesis in patients of the ‘‘expanded indications group’’. 5th annual global symposium Spine Arthroplasty Society (SA5); 2005; New York, NY. [64] Bertagnoli R, Kumar S. Indications for full prosthetic disc arthroplasty: a correlation of clinical outcome against a variety of indications. Eur Spine J 2002;11(2 Suppl):S131–6. [65] David T. Lumbar disc prosthesis: surgical technique, indications and clinical results in 22 patients with a minimum of 12 months followup. Eur Spine J 1993;1:254–9. [66] Freeman BJ, Davenport J. Total disc replacement in the lumbar spine: a systematic review of the literature. Eur Spine J 2006;15: 439–47. [67] Siepe CJ, Heider F, Haas E, et al. Influence of lumbar intervertebral disc degeneration on the outcome of total lumbar disc replacement: a prospective clinical, histological, x-ray and MRI investigation. Eur Spine J 2012;21:2287–99. [68] Siepe CJ, Hitzl W, Meschede P, et al. Interdependence between disc space height, range of motion and clinical outcome in total lumbar disc replacement. Spine 2009;34:904–16. [69] Leivseth G, Braaten S, Frobin W, et al. Mobility of lumbar segments instrumented with a ProDisc II prosthesis: a two-year follow-up study. Spine 2006;31:1726–33. [70] Yaszay B, Bendo JA, Goldstein JA, et al. Effect of intervertebral disc height on postoperative motion and outcomes after ProDisc-L lumbar disc replacement. Spine 2008;33:508–12; discussion 513.

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[71] Shim CS, Lee SH, Shin HD, et al. CHARITE versus ProDisc: a comparative study of a minimum 3-year follow-up. Spine 2007;32: 1012–8. [72] Cakir B, Richter M, Kafer W, et al. The impact of total lumbar disc replacement on segmental and total lumbar lordosis. Clin Biomech (Bristol, Avon) 2005;20:357–64. [73] Liu J, Ebraheim NA, Haman SP, et al. Effect of the increase in the height of lumbar disc space on facet joint articulation area in sagittal plane. Spine 2006;31:E198–202. [74] Rohlmann A, Zander T, Bergmann G. Effect of total disc replacement with ProDisc on intersegmental rotation of the lumbar spine. Spine 2005;30:738–43. [75] Huang RC, Girardi FP, Cammisa FP Jr, et al. Correlation between range of motion and outcome after lumbar total disc replacement: 8.6-year follow-up. Spine 2005;30:1407–11. [76] Chung SS, Lee CS, Kang CS, et al. The effect of lumbar total disc replacement on the spinopelvic alignment and range of motion of the lumbar spine. J Spinal Disord Tech 2006;19:307–11. [77] Le Huec J, Basso Y, Mathews H, et al. The effect of single-level, total disc arthroplasty on sagittal balance parameters: a prospective study. Eur Spine J 2005;14:480–6. [78] Le Huec JC, Basso Y, Aunoble S, et al. Influence of facet and posterior muscle degeneration on clinical results of lumbar total disc replacement: two-year follow-up. J Spinal Disord Tech 2005;18: 219–23. [79] Tournier C, Aunoble S, Le Huec JC, et al. Total disc arthroplasty: consequences for sagittal balance and lumbar spine movement. Eur Spine J 2007;16:411–21. [80] Zindrick MR, Tzermiadianos MN, Voronov LI, et al. An evidence-based medicine approach in determining factors that may affect outcome in lumbar total disc replacement. Spine 2008;33:1262–9. [81] Nunley PD, Jawahar A, Mukherjee DP, et al. Comparison of pressure effects on adjacent disk levels after 2-level lumbar constructs: fusion, hybrid, and total disk replacement. Surg Neurol 2008;70: 247–51; discussion 251. [82] Chung SK, Kim YE, Wang KC. Biomechanical effect of constraint in lumbar total disc replacement: a study with finite element analysis. Spine 2009;34:1281–6. [83] Le Huec JC, Lafage V, Bonnet X, et al. Validated finite element analysis of the maverick total disc prosthesis. J Spinal Disord Tech 2010;23:249–57. [84] Botolin S, Puttlitz C, Baldini T, et al. Facet joint biomechanics at the treated and adjacent levels after total disc replacement. Spine 2011;36:E27–32. [85] Chen SH, Zhong ZC, Chen CS, et al. Biomechanical comparison between lumbar disc arthroplasty and fusion. Med Eng Phys 2009;31: 244–53. [86] Cunningham BW, Gordon JD, Dmitriev AE, et al. Biomechanical evaluation of total disc replacement arthroplasty: an in vitro human cadaveric model. Spine 2003;28:S110–7. [87] Denoziere G, Ku DN. Biomechanical comparison between fusion of two vertebrae and implantation of an artificial intervertebral disc. J Biomech 2006;39:766–75. [88] Erkan S, Rivera Y, Wu C, et al. Biomechanical comparison of a twolevel Maverick disc replacement with a hybrid one-level disc replacement and one-level anterior lumbar interbody fusion. Spine J 2009;9:830–5. [89] Grauer JN, Biyani A, Faizan A, et al. Biomechanics of two-level Charite artificial disc placement in comparison to fusion plus single-level disc placement combination. Spine J 2006;6:659–66. [90] Hitchon PW, Eichholz K, Barry C, et al. Biomechanical studies of an artificial disc implant in the human cadaveric spine. J Neurosurg Spine 2005;2:339–43. [91] Link HD. History, design and biomechanics of the LINK SB Charite artificial disc. Eur Spine J 2002;11(2 Suppl):S98–105.

-

(2013)

-

[92] McAfee PC, Cunningham BW, Hayes V, et al. Biomechanical analysis of rotational motions after disc arthroplasty: implications for patients with adult deformities. Spine 2006;31:S152–60. [93] Moumene M, Geisler FH. Comparison of biomechanical function at ideal and varied surgical placement for two lumbar artificial disc implant designs: mobile-core versus fixed-core. Spine 2007;32: 1840–51. [94] Quirno M, Kamerlink JR, Valdevit A, et al. Biomechanical analysis of a disc prosthesis distal to a scoliosis model. Spine 2009;34: 1470–5. [95] Rohlmann A, Mann A, Zander T, et al. Effect of an artificial disc on lumbar spine biomechanics: a probabilistic finite element study. Eur Spine J 2009;18:89–97. [96] Wilke HJ, Schmidt R, Richter M, et al. The role of prosthesis design on segmental biomechanics: semi-constrained versus unconstrained prostheses and anterior versus posterior centre of rotation. Eur Spine J 2012;21:S577–84. [97] Zander T, Rohlmann A, Bergmann G. Influence of different artificial disc kinematics on spine biomechanics. Clin Biomech (Bristol, Avon) 2009;24:135–42. [98] Dmitriev AE, Gill NW, Kuklo TR, et al. The effect of multilevel lumbar disc arthroplasty on the operative- and adjacent-level kinematics and intradiscal pressures. An in vitro human cadaveric assessment. Spine J 2008;8:918–25. [99] Goel VK, Grauer JN, Patel T, et al. Effects of charite artificial disc on the implanted and adjacent spinal segments mechanics using a hybrid testing protocol. Spine 2005;30:2755–64. [100] Panjabi M, Malcolmson G, Teng E, et al. Hybrid testing of lumbar CHARITE discs versus fusions. Spine 2007;32:959–66; discussion 967. [101] Ruberte LM, Natarajan RN, Andersson GB. Influence of singlelevel lumbar degenerative disc disease on the behavior of the adjacent segments–a finite element model study. J Biomech 2009;42: 341–8. [102] Cinotti G, David T, Postacchini F. Results of disc prosthesis after a minimum follow-up period of 2 years. Spine 1996;21:995–1000. [103] Lemaire JP, Skalli W, Lavaste F, et al. Intervertebral disc prosthesis. Results and prospects for the year 2000. Clin Orthop Relat Res 1997;64–76. [104] Tropiano P, Huang RC, Girardi FP, et al. Lumbar disc replacement: preliminary results with ProDisc II after a minimum follow-up period of 1 year. J Spinal Disord Tech 2003;16:362–8. [105] Aghayev E, Roder C, Zweig T, et al. Benchmarking in the SWISSspine registry: results of 52 Dynardi lumbar total disc replacements compared with the data pool of 431 other lumbar disc prostheses. Eur Spine J 2010;19:2190–9. [106] Lemaire JP, Carrier H, Ali el HS, et al. Clinical and radiological outcomes with the Charite artificial disc: a 10-year minimum followup. J Spinal Disord Tech 2005;18:353–9. [107] Griffith SL, Shelokov AP, Buttner-Janz K, et al. A multicenter retrospective study of the clinical results of the LINK SB Charite intervertebral prosthesis. The initial European experience. Spine 1994;19:1842–9. [108] Carreon LY, Puno RM, Dimar JR 2nd, et al. Perioperative complications of posterior lumbar decompression and arthrodesis in older adults. J Bone Joint Surg Am 2003;85-A:2089–92. [109] Howe CR, Agel J, Lee MJ, et al. The morbidity and mortality of fusions from the thoracic spine to the pelvis in the adult population. Spine 2011;36:1397–401. [110] Malter AD, McNeney B, Loeser JD, et al. 5-year reoperation rates after different types of lumbar spine surgery. Spine 1998;23:814–20. [111] Martin BI, Mirza SK, Comstock BA, et al. Reoperation rates following lumbar spine surgery and the influence of spinal fusion procedures. Spine 2007;32:382–7. [112] Zigler J, Guyer RD, Blumenthal S, et al. Analysis of re-operations after lumbar total disc replacement: experience in 1000 consecutive

C.J. Siepe et al. / The Spine Journal

[113]

[114]

[115]

[116] [117]

[118]

[119]

[120]

[121]

patients beginning with first case experience of 11 surgeons. Barcelona, Spain: AO Spine Global Spine Congress (GSC), 2011. McAfee PC, Geisler FH, Saiedy SS, et al. Revisability of the CHARITE artificial disc replacement: analysis of 688 patients enrolled in the U.S. IDE study of the CHARITE Artificial Disc. Spine 2006;31:1217–26. Bertagnoli R, Yue JJ, Shah RV, et al. The treatment of disabling multilevel lumbar discogenic low back pain with total disc arthroplasty utilizing the ProDisc prosthesis: a prospective study with 2-year minimum follow-up. Spine 2005;30:2192–9. Delamarter RB, Bae HW, Kropf MA, et al. 1 versus 2 versus 3-level lumbar artificial disc replacement - a prospective report of clinical outcomes with the ProDisc-L device. Annual meeting of the international Society for the Study of the Lumbar Spine (ISSLS); 2006; Bergen, Norway. Di Silvestre M, Bakaloudis G, Lolli F, et al. Two-level total lumbar disc replacement. Eur Spine J 2009;18(1 Suppl):64–70. Hannibal M, Thomas DJ, Low J, et al. ProDisc-L total disc replacement: a comparison of 1-level versus 2-level arthroplasty patients with a minimum 2-year follow-up. Spine 2007;32:2322–6. Zigler JE, Sachs BL, Rashbaum RF, et al. Two level total lumbar disc replacement with ProDisc: results and comparison to one level cases. Proceedings of the NASS 20th annual meeting. Philadelphia, PA: Spine J, 20054S–5S. Siepe CJ, Korge A, Grochulla F, et al. Analysis of post-operative pain patterns following total lumbar disc replacement: results from fluoroscopically guided spine infiltrations. Eur Spine J 2008;17:44–56. Siepe CJ, Mayer HM, Heinz-Leisenheimer M, et al. Total lumbar disc replacement: different results for different levels. Spine 2007;32:782–90. Sariali el H, Lemaire JP, Pascal-Mousselard H, et al. In vivo study of the kinematics in axial rotation of the lumbar spine after total intervertebral disc replacement: long-term results: a 10-14 years follow up evaluation. Eur Spine J 2006;15:1501–10.

-

(2013)

-

15

[122] Sinigaglia R, Bundy A, Costantini S, et al. Comparison of singlelevel L4-L5 versus L5-S1 lumbar disc replacement: results and prognostic factors. Eur Spine J 2009;18(1 Suppl):52–63. [123] Siepe CJ, Tepass A, Hitzl W, et al. Dynamics of improvement following total lumbar disc replacement: is the outcome predictable? Spine 2009;34:2579–86. [124] Wang JC, Shapiro MS, Hatch JD, et al. The outcome of lumbar discectomy in elite athletes. Spine 1999;24:570–3. [125] David T. Long-term results of one-level lumbar arthroplasty: minimum 10-year follow-up of the CHARITE artificial disc in 106 patients. Spine 2007;32:661–6. [126] Le Huec JC, Mathews H, Basso Y, et al. Clinical results of Maverick lumbar total disc replacement: two-year prospective follow-up. Orthop Clin North Am 2005;36:315–22. [127] Tropiano P, Huang RC, Girardi FP, et al. Lumbar total disc replacement. Seven to eleven-year follow-up. J Bone Joint Surg Am 2005;87-A:490–6. [128] Bertagnoli R, Yue JJ, Kershaw T, et al. Lumbar total disc arthroplasty utilizing the ProDisc prosthesis in smokers versus nonsmokers: a prospective study with 2-year minimum follow-up. Spine 2006;31:992–7. [129] Park CK, Ryu KS, Lee KY, et al. Clinical outcome of lumbar total disc replacement using ProDisc-L in degenerative disc disease: minimum 5-year follow-up results at a single institute. Spine 2012;37: 672–7. [130] Berg S, Tullberg T, Branth B, et al. Total disc replacement compared to lumbar fusion: a randomised controlled trial with 2-year followup. Eur Spine J 2009;18:1512–9. [131] Putzier M, Funk JF, Schneider SV, et al. Charite total disc replacement-clinical and radiographical results after an average follow-up of 17 years. Eur Spine J 2006;15:183–95. [132] Scott-Young MN, Lee MJ, Nielsen DE, et al. Clinical and radiological mid-term outcomes of lumbar single-level total disc replacement. Spine 2011.