Single-level Total Disc Replacement Research Articles

P103. Seven-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc

P103. Seven-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc

6-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc

6-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc

Single-Level Total Disc Replacement: Mid- to Long-Term Outcomes.

Total disc replacement (TDR) has been shown to be effective for the treatment of lumbar degenerative disc disease (DDD) in carefully selected patients. Previous studies have demonstrated high rates of patient satisfaction and improvement in patient-reported outcome measures (PROMs) compared with preoperative status but most have short-term follow-up or small cohort sizes only. The aim of this study is to report mid- to long-term PROMs from the treatment of symptomatic single-level lumbar DDD with TDR. Data collected prospectively concerning single-level TDR performed via an anterior approach were included for analysis. A preoperative assessment was obtained followed by postoperative follow-up assessments at 3, 6, and 12 months, and yearly follow-up thereafter. PROMs included patient satisfaction, visual analog score back and leg, Oswestry Disability Index, and Roland-Morris Disability Questionnaire. A total of 211 patients (118 men, 93 women) operated on between June 1997 and July 2015 were included in this study. Minimum follow-up was 4 years. The average age was 42.2 (range 24-87) years and median follow-up 96 interquartile range 72-132, range 48-120) months. The operative levels were L5-S1 (160, 75.8%) and L4-L5 (61, 24.2%). Both statistically and clinically significant improvements observed postoperatively were maintained at 10 years. In addition, 92% of patients reported either good (n = 29) or excellent satisfaction (n = 155) with treatment at final review. This study shows that single-level lumbar TDR used appropriately in selected patient results in clinically significant improvements in pain and function, well above the minimum clinically important difference, and good to excellent satisfaction in most patients. Further study to define long-term outcomes and survivorship is required. Statistically significant and clinically relevant improvements can be achieved by single-level lumbar TDR, in the treatment of single-level discogenic axial low back pain, with or without radiculopathy. These outcomes are sustained in the mid- to long-term followup periods.

Single-Level Total Disc Replacement: Index-Level and Adjacent-Level Revision Surgery Incidence, Characteristics, and Outcomes.

The literature reports that index level (IL) revision spine surgery (RSS) and adjacent level (AL) RSS are diminished in lumbar TDR compared with fusion procedures. There is a paucity of PROMs reported after RSS. To present the incidence of RSS at the IL and AL following single-level lumbar total disc replacement (TDR) and to document patient-related outcome measures (PROMs) associated with RSS. PROMs and timelines were analyzed for 32 RSS patients from a prospective cohort study of 401 patients treated with TDR for single-level degenerative disc disease. The data collected prospectively are analyzed from baseline (prior to index surgery) to latest follow-up following RSS. PROMs, including visual analog scales for back and leg, Oswestry Disability Index, and Roland-Morris Disability Questionnaire, were collected preoperatively; postoperatively at 3, 6, and 12 months; and annually thereafter until RSS. The time to RSS was recorded, and PROMs for RSS (IL, AL, or both) were documented, analyzed, and compared. The median time to RSS in the IL cohort was 35 months (interquartile range [IQR] = 9-51 months). The median time to RSS cohort was 70 months (IQR = 41.3-105.3 months). Timepoints facilitate PROM discussion for RSS. Patients in both groups achieved thresholds for the minimum clinically important difference for pain and disability scores. The small sample size in each group contributed to the variability demonstrated by the 95% CIs, thereby cautioning definitive conclusions. This study reveals that statistically significant and modest clinical improvements in PROMs can be achieved in RSS for lumbar TDR at IL and AL. The surgical approach and technique are reflective of the pathology and suggest that anterior RSS for AL degeneration and posterior RSS for IL pathology yield similar results. Statistical and clinical improvements can be achieved in IL-RSS and AL-RSS following single level TDR. It is essential for clinicians to understand and verify the underlying IL and/or AL pathology to select an appropriate management strategy and to facilitate balanced informed discussions with patients.

159. Midterm 4-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc compared to ACDF

<h3>BACKGROUND CONTEXT</h3> The M6-C artificial cervical disc, with a compressible viscoelastic nuclear core and an annular structure, is substantially different from first generation articulating surface designs and has previously demonstrated favorable clinical outcomes out to 2-years post-implantation. <h3>PURPOSE</h3> To evaluate the safety and effectiveness of the M6-C artificial cervical disc compared with ACDF. <h3>STUDY DESIGN/SETTING</h3> A prospective, multicenter, controlled, IDE clinical trial is ongoing. Twelve M6-C sites and 11 ACDF sites are participating in the study, with preoperative assessments followed by assessments at 6 weeks, 3 months, 6 months, 1 year and annually out to 10 years postimplantation. <h3>PATIENT SAMPLE</h3> Study subjects presented with one-level symptomatic degenerative cervical radiculopathy, and received either M6-C or ACDF at a single level. <h3>OUTCOME MEASURES</h3> Neck Disability Index (NDI), neck pain and shoulder/arm pain visual analog scale (VAS) scores. <h3>Methods</h3> The M6-C and ACDF cohorts were propensity matched. Follow-up assessments are ongoing and planned out to 10-years postop. <h3>Results</h3> A total of 160 M6-C and 189 ACDF subjects were enrolled. NDI scores are available for 124 M6-C and 148 ACDF subjects at 3 years, and 116 M6-C and 133 ACDF subjects at 4 years postop. At 3 years postop, M6-C subjects had a mean NDI score of 10.9 - significantly better than the mean of 17.2 observed in the ACDF group. A significant difference was observed at 4 years postop (M6-C mean of 10.3 compared to 19.2 for ACDF.) M6-C subjects experienced a mean improvement from baseline of 43.9 points at 3-years and 45.2 points at 4-years postop, compared to 36.0 and 36.0, respectively, for the ACDF cohort, with the 4-year results being significantly better for the M6-C group. More M6-C subjects experienced a 15-point improvement from baseline (93.6% at 3 years and 95.7% at 4 years,) compared to the ACDF cohort (86.6% and 82.7%, respectively,) with the 4-year results being significantly better for the M6-C group. Neck pain and shoulder/arm pain VAS scores are available for analysis for 124 M6-C and 148 ACDF subjects at 3 years, and 116 M6-C and 134 ACDF subjects at 4 years postop. At 3 years postop, M6-C subjects had a mean neck pain VAS score of 1.1, which was significantly better than the mean of 2.0 observed in the ACDF control group. Similarly, a significant difference was observed at 4 years postop (M6-C mean of 1.0 compared to 2.3 for ACDF.) M6-C subjects experienced a mean improvement from baseline of 6.1 points at 3-years and 6.2 points at 4-years postop, compared to 5.2 and 4.8, respectively, for the ACDF cohort, both significantly better for the M6-C group. Similarly significant results were observed in shoulder/arm pain VAS scores (worst side) at 3-years (0.9 for M6-C and 2.2 for ACDF) and 4-years postop (0.6 for M6-C and 2.7 for ACDF.) One M6-C subject (0.6%) had the device removed in the first 4 postop years (chronic neck pain.) <h3>Conclusions</h3> The significant benefits in NDI and neck pain and shoulder/arm pain VAS scores associated with M6-C in earlier follow-up periods, compared to ACDF controls, appear to be maintained at 3- and 4-years postop, with no concerns for durability of the surgical outcome or the prosthesis at 4 years. Both NDI and neck pain and shoulder/arm pain will continue to be monitored in this cohort via annual assessments out to 10-years postop. <h3>FDA DEVICE/DRUG STATUS</h3> M6 TDR (Approved for this indication)

Retrospective study on effectiveness of Activ L total disc replacement

BackgroundThe effectiveness of lumbar total disc replacement (TDR) with different prostheses for sagittal alignment has been reported previously. However, there are only few reports on Activ L TDR and no specific evidence regarding whether sagittal alignment affects the clinical outcomes.MethodsEighty-seven patients who underwent mono- or bi-segmental lumbar TDR with Activ L were studied. The films of the upright anteroposterior and lateral spine in neutral, flexion, and extension positions were obtained before surgery and at 1 month and 1 and 3 years after surgery. The radiographic parameters such as lumbar lordosis (LL), index level lordosis (IL), pelvic incidence (PI), pelvic tilt (PT), segmental lordosis (SL), and sacral slope (SS) were measured based on the lateral upright radiographs. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS) pre- and post-operatively.ResultsEighty-seven patients with complete radiographic data were available for a 3-year follow-up period. Of these, 66 received a single-level TDR, and 21 received a 2-level TDR. At 1 month, the mean LL was similar to the pre-operative data and then was significantly increased to 45.1° at 3 years. On average, the IL tended to significantly increase, while the mean SL at L–5 was increased from 16.5° pre-operatively to 21.0° at 3 years. The mean SL at L1–2, L2–3, L3–4, and L5–S1; PI; PT; and SS showed no obvious difference after 3 years. In contrast, VAS and ODI scores showed significant improvement after surgery.ConclusionsActiv L TDR showed a favorable effect on sagittal alignment, enhancing the IL while preserving the LL and SS. However, satisfactory clinical results for over a 3-year follow-up were not affected by sagittal alignment.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P63. Pain-related safety outcomes seven years following lumbar total disc replacement in mobile core devices versus constrained core devices

BACKGROUND CONTEXT Total disc replacement (TDR) is an alterative to fusion for treating patients with disabling discogenic back pain. While several studies report significant improvements in overall back pain following TDR, some patients may experience recurring episodes of pain in the lumbar and/or lower extremities. Competing lumbar disc arthroplasty devices include a mobile core device versus a constrained core device. Long-term follow up (>7 years) from investigational device trials is now available to better assess long-term outcomes with arthroplasty with the two device types. PURPOSE To evaluate pain-related adverse events in patients 7years following single-level total disc replacement at L4–L5 or L5–S1 with either a mobile core disc (MCD) or a constrained core device (CCD) to determine if implant design is associated with increased pain serious adverse effects at 7-year follow-up. STUDY DESIGN/SETTING This post-hoc analysis of a multicenter, prospective, randomized, controlled, investigational device exemption trial included patients with symptomatic lumbar degenerative disc disease at L4–L5 or L5–S1. PATIENT SAMPLE The patients had lumbar arthroplasty surgery with either an MCD (n=218) or CCD (n=65) implant and were randomized prior to surgery in the IDE study. OUTCOME MEASURES The study reviewed events deemed to be serious adverse events in a FDA IDE study. METHODS This post-hoc analysis of a multicenter, prospective, randomized, controlled, investigational device exemption trial included patients with symptomatic lumbar degenerative disc disease at L4–L5 or L5–S1. Pain related adverse events (AE) at 7years post implantation for TDRs as a class and by device type (MCD vs. CCD) are reported. RESULTS Of the reported AEs, 23% (N=327) were categorized as pain of the lumbar and/or lower extremities: lumbar only (7%), lumbar and bilateral lower leg (5%), and lumbar and unilateral lower leg (3%). Patients presenting with AEs reported an average of two pain related AEs at 7years post-op. Of the pain related AEs, 11% were device related, 8% were procedure related and 9% were serious AEs (SAEs). Onset of the first pain related SAE occurred on average at 49days (range: 0–118 days) and 395days (range: 0–2,728 days) following CCD and MCD implantation, respectively (p=.21). Overall, the majority of pain related SAEs were classified as severe (69%). A greater proportion of patients implanted with the CCD device presented with severe SAEs (88%) compared to patients with MCD (61%; p=.17). At the 7-year follow-up, over half of the SAEs occurring in MCD patients were resolved (56%) while the SAEs in CCD patients remained mostly unresolved (75%; p=.14). CONCLUSIONS While the rate of pain related AEs were the same between patients implanted with an MCD or CCD implant, there were observed differences in the quality of SAEs between the two TDR devices. On average, the first pain related SAE in MCD patients occurred approximately 1 year after CCD patients. Furthermore, a smaller proportion of SAEs were severe and a greater proportion was resolved by the 7-year follow-up appointment with MCD versus CCD implanted patients.

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

Prospective single-center case cohort study. Evaluation of clinical and radiographic outcomes of a consecutive 122-patient cohort with discogenic back pain, at 2- to 10-year follow-up periods, treated by a single surgeon, with CHARITÉ Artificial Disc (DePuy Spine, Raynham, MA). Minimum 2-year clinical and radiographic level 1 data for the first lumbar artificial disc, the CHARITÉ Artificial Disc (DePuy Spine), have recently been published, demonstrating sustained clinical benefit of the device for the treatment of degenerative disc disease. Patients were assessed preoperatively using clinical outcome measures, including visual analog scale (VAS) score back and leg, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36), and Roland-Morris Questionnaires (RMDQ), and further assessed postoperatively, 3-, 6-, 12-months, and yearly thereafter. Average follow-up was 44.9 ± 23.3 months (n = 122). The median age at surgery was 43.0 ± 9.0 years. Preoperative diagnosis included degenerative disc disease in 118 (96.7%) and internal disc disruption in 4 (3.3%). Surgery was performed at L5-S1 in 96 (77.9%) patients and at L4-L5 in 27 (22.1%). Statistically significant clinical improvements from baseline were observed on VAS (back and leg), ODI, SF-36 PCS, SF-36 MCS, and RMDQ 3 months onward. Back VAS scores decreased from 78.2 ± 21.3 preoperatively to 21.9 ± 27.8 by final follow-up. ODI scores decreased from 51.1 ± 17.3 to 16.2 ± 17.9 at last follow-up. The RMDQ scores also decreased from 16.7 ± 4.7 to 4.2 ± 5.8. SF-36 PCS and MCS increased from 25.7 ± 11.0 to 46.4 ± 10.3 for PCS and from 35.5 ± 17.4 to 51.6 ± 10.8 for MCS. Patient satisfaction surveys indicated that 90.56% patients rated their satisfaction with the surgery as "excellent" or "good" at 2 years. Range of motion averaged 8.6 ± 3.5 (median = 8.0°) at the last follow-up time point. Outcomes verify the clinical efficacy of total disc replacement for treatment of discogenic back pain with or without radiculopathy. The outcomes instruments demonstrated statistically significant improvements 3 months onward. N/A.

Clinical and radiologic comparison of dynamic cervical implant arthroplasty and cervical total disc replacement for single-level cervical degenerative disc disease

Anterior cervical discectomy and fusion, to date the most successful spine procedure for the surgical treatment of cervical radiculopathy, has limitations that have led to the development of non-fusion cervical procedures, such as cervical total disc replacement (TDR) and dynamic cervical implant (DCI) arthroplasty. We compared the clinical and radiological results of DCI and cervical TDR for the treatment of single-level cervical degenerative disc disease in Chinese patients. A retrospective review of 179 patients with cervical spondylotic myelopathy who underwent DCI or TDR between April 2010 and October 2012 was conducted, and 152 consecutive patients (67 patients single-level DCI and 85 single-level TDR) who completed at least 2years of follow-up were included. Clinical and radiological assessments were performed preoperatively and at 1week and 3, 6, 12, and 24months postoperatively. The most common operative level was C5/C6 (49.3%). The differences in blood loss, duration of surgery, and duration of hospitalization were not statistically significant. The Japanese Orthopaedic Association scale, Visual Analog Scale, Neck Disability Index, and Short Form-36 scores improved significantly after surgery in both the DCI and TDR groups (P<0.05), but the differences were not statistically significant at the final follow-up. The rate of occurrence of heterotopic ossification was 22.4% and 28.2% in the DCI and TDR groups, respectively. As an effective non-fusion technique, DCI is a more economical procedure. Further prospective, randomized studies with long-term follow-up periods are needed to determine the long-term effects.

Biomechanical Analysis of Cervical Disc Replacement and Fusion Using Single Level, Two Level, and Hybrid Constructs.

A biomechanical study comparing arthroplasty with fusion using human cadaveric C2-T1 spines. To compare the kinematics of the cervical spine after arthroplasty and fusion using single level, 2 level and hybrid constructs. Previous studies have shown that spinal levels adjacent to a fusion experience increased motion and higher stress which may lead to adjacent segment disc degeneration. Cervical arthroplasty achieves similar decompression but preserves the motion at the operated level, potentially decreasing the occurrence of adjacent segment disc degeneration. 11 specimens (C2-T1) were divided into 2 groups (BRYAN and PRESTIGE LP). The specimens were tested in the following order; intact, single level total disc replacement (TDR) at C5-C6, 2-level TDR at C5-C6-C7, fusion at C5-C6 and TDR at C6-C7 (Hybrid construct), and lastly a 2-level fusion. The intact specimens were tested up to a moment of 2.0 Nm. After each surgical intervention, the specimens were loaded until the primary motion (C2-T1) matched the motion of the respective intact state (hybrid control). An arthroplasty preserved motion at the implanted level and maintained normal motion at the nonoperative levels. Arthrodesis resulted in a significant decrease in motion at the fused level and an increase in motion at the unfused levels. In the hybrid construct, the TDR adjacent to fusion preserved motion at the arthroplasty level, thereby reducing the demand on the other levels. Cervical disc arthroplasty with both the BRYAN and PRESTIGE LP discs not only preserved the motion at the operated level, but also maintained the normal motion at the adjacent levels. Under simulated physiologic loading, the motion patterns of the spine with the BRYAN or PRESTIGE LP disc were very similar and were closer than fusion to the intact motion pattern. An adjacent segment disc replacement is biomechanically favorable to a fusion in the presence of a pre-existing fusion.

The effect of deviated center of rotation on flexion-extension range of motion after single-level cervical arthroplasty: an in vivo study.

A retrospective study. To report the clinical outcomes and sagittal kinematics after cervical total disc replacement (TDR). To evaluate the in vivo effect of deviated center of rotation (COR) on flexion-extension range of motion (ROM) at the instrumented level. A few studies showed that the location of COR after cervical TDR deviated from its preoperative location or inherent location in healthy subjects. However, little is known about the effect of deviated COR on ROM at the instrumented level. A total of 24 patients who underwent C5-C6 single-level TDR with Prestige LP (Medtronic Sofamor Danek) were retrospectively included. Japanese Orthopedic Association score and visual analogue scale were used to assess the clinical outcomes. ROM and COR were measured for radiographical analysis. Patients were categorized into 2 groups according to the change of ROM for further evaluation. Group 1, characterized by decreased postoperative ROM, consisted of 16 patients; group 2, characterized by increased postoperative ROM, consisted of 8 patients. Ten males and 14 females comprised the study cohort. The mean age was 45.05 years, and the mean follow-up time was 15.5 months. The Japanese Orthopedic Association score increased significantly and the neck and arm visual analogue scale decreased significantly after cervical TDR. On average, ROM was preserved after cervical TDR. The postoperative COR had a significant cranial shift from its preoperative location. The COR shift in anterior-posterior direction was larger in group 2 than that in group 1. No difference was observed in the COR shift in cranial-caudal direction between the 2 groups. Single-level cervical TDR with Prestige LP obtained satisfactory clinical outcomes and partially restored the natural cervical kinematics. At instrumented level, the deviated COR had a negative correlation with the flexion-extension ROM.

Clinical outcomes, radiologic kinematics, and effects on sagittal balance of the 6 df LP-ESP lumbar disc prosthesis

Background contextSurgical treatment of degenerative disc disease remains a controversial subject. Lumbar fusion has been associated with a potential risk of segmental junctional disease and sagittal balance misalignment. Motion preservation devices have been developed as an alternative to fusion. The LP-ESP disc is a one-piece deformable device achieving 6 df, including shock absorption and elastic return. This is the first clinical report on its use. PurposeTo assess clinical outcomes and radiologic kinematics in the first 2 years after implantation. Study designProspective cohort of patients with LP-ESP total disc replacement (TDR) at the lumbar spine. Patient sampleForty-six consecutive patients. Outcome measuresClinical outcomes were the visual analog scale (VAS) for pain, the Oswestry disability index (ODI), and the GHQ28 (General Health Questionnaire) psychological score. Radiologic data were the range of motion (ROM), sagittal balance parameters, and mean center of rotation (MCR). MethodsPatients had single-level TDR at L4–L5 or L5–S1. Outcomes were prospectively recorded for 2 years (before and at 3, 6, 12, and 24 months after surgery). The SpineView software was used for computed analysis of the radiographic data. Paired t tests were used for statistical comparisons. ResultsNo intraoperative complication occurred. All clinical scores improved significantly at 24 months: the back pain VAS scores by a mean of 4.1 points and the ODI by 33 points. The average ROM of the instrumented level was 5.4°±4.8° at 2 years and more than 2° for 76% of prostheses. The MCR was in a physiological area in 73% of cases. The sagittal balance (pelvic tilt, sacral slope, and segmental lordosis) did not change significantly at any point of the follow-up. ConclusionsResults from the 2-year follow-up indicate that LP-ESP prosthesis recreates lumbar spine function similar to that of the healthy disc in terms of ROM, quality of movement, effect on sagittal balance, and absence of modification in the kinematics of the upper adjacent level.

The importance of the anterior longitudinal ligament in lumbar disc arthroplasty: 36-Month follow-up experience in extreme lateral total disc replacement

BackgroundCurrent total disc replacement (TDR) for lumbar spine requires an anterior approach for implantation but presents inherent limitations, including risks to the abdominal structures, as well as resection of the anterior longitudinal ligament. By approaching the spine laterally, it is possible to preserve the stabilizing ligaments, which are a natural restraint to excessive rotations and translations, and thereby help to minimize facet stresses. This less invasive approach also offers a biomechanical advantage of placement of the device over the ring apophysis bilaterally; importantly, it also offers a greater opportunity for safer revision surgery, if necessary, by avoiding scarring of the anterior vasculature. We present the clinical and radiologic results of a lateral TDR device from a prospective single-center study. MethodsA new metal-on-metal TDR device designed for implantation through a true lateral, retroperitoneal, transpsoatic approach (extreme lateral interbody fusion) was implanted in 36 patients with discography-confirmed 1- or 2-level degenerative disc disease. Clinical (pain and function) and radiographic (range of motion) outcome assessments were prospectively collected preoperatively, postoperatively, and serially up to a minimum of 36 months' follow-up. ResultsBetween December 2005 and December 2006, 36 surgeries were performed in 16 men and 20 women (mean age, 42.6 years). These included 15 single-level TDR procedures at L3-4 or L4-5, 3 2-level TDR procedures spanning L3-4 and L4-5, and 18 hybrid procedures (anterior lumbar interbody fusion) at L5-S1 and TDR at L4-5 (17) or L3-4 (1). Operative time averaged 130 minutes, with mean blood loss of 60 mL and no intraoperative complications. Postoperative X-rays showed good device placement, with restoration of disc height, foraminal volume, and sagittal balance. All patients were up and walking within 12 hours of surgery, and all but 9 were discharged the next day (7 of those 9 were hybrid TDR–anterior lumbar interbody fusion cases). Postoperatively, 5 of 36 patients (13.8%) had psoas weakness and 3 of 36 (8.3%) had anterior thigh numbness, with both symptoms resolving within 2 weeks. Of the 36 patients, 4 (11%) had postoperative facet joint pain, all in hybrid cases. Visual analog scale pain scores and Oswestry Disability Index scores improved by 74.5% and 69.2%, respectively, from preoperatively to 3-year follow-up. Range of motion at 3 years postoperatively averaged 8.1°. Signals of heterotopic ossification were present in 5 patients (13.9%), and 2 patients (5.5%) were considered to have fusion after 36 months. ConclusionsThe clinical and radiographic results of a laterally placed TDR have shown maintenance of pain relief and functional improvement over a long-term follow-up period. The benefits of the lateral access—minimal morbidity, avoidance of mobilization of the great vessels, preservation of the anterior longitudinal ligament, biomechanically stable orientation, and broader revision options—promote a new option for motion-preservation procedures.

The Correlation between Insertion Depth of Prodisc-C Artificial Disc and Postoperative Kyphotic Deformity: Clinical Importance of Insertion Depth of Artificial Disc.

ObjectiveThis study was designed to investigate the correlation between insertion depth of artificial disc and postoperative kyphotic deformity after Prodisc-C total disc replacement surgery, and the range of artificial disc insertion depth which is effective in preventing postoperative whole cervical or segmental kyphotic deformity.MethodsA retrospective radiological analysis was performed in 50 patients who had undergone single level total disc replacement surgery. Records were reviewed to obtain demographic data. Preoperative and postoperative radiographs were assessed to determine C2-7 Cobb's angle and segmental angle and to investigate postoperative kyphotic deformity. A formula was introduced to calculate insertion depth of Prodisc-C artificial disc. Statistical analysis was performed to search the correlation between insertion depth of Prodisc-C artificial disc and postoperative kyphotic deformity, and to estimate insertion depth of Prodisc-C artificial disc to prevent postoperative kyphotic deformity.ResultsIn this study no significant statistical correlation was observed between insertion depth of Prodisc-C artificial disc and postoperative kyphotic deformity regarding C2-7 Cobb's angle. Statistical correlation between insertion depth of Prodisc-C artificial disc and postoperative kyphotic deformity was observed regarding segmental angle (p<0.05). It failed to estimate proper insertion depth of Prodisc-C artificial disc effective in preventing postoperative kyphotic deformity.ConclusionPostoperative segmental kyphotic deformity is associated with insertion depth of Prodisc-C artificial disc. Anterior located artificial disc leads to lordotic segmental angle and posterior located artificial disc leads to kyphotic segmental angle postoperatively. But C2-7 Cobb's angle is not affected by artificial disc location after the surgery.

Index and Adjacent Level Kinematics After Cervical Disc Replacement and Anterior Fusion

Prospective, randomized trial. To assess the in vivo kinematics of the cervical spine after cervical fusion and arthroplasty. Compared with spinal fusion, disc replacement may impede the development of adjacent segment disease. To achieve this goal, any arthroplasty device should achieve desired spinal alignment while maintaining physiologic spinal motion at both the operated and surrounding motion segments. As part of a multicenter, prospective, randomized Food and Drug Administration IDE clinical evaluation of the porous coated motion artificial cervical disc, patients underwent either a single-level total disc replacement (TDR; 272 patients) or anterior cervical discectomy and fusion (ACDF; 182 patients) for treatment of cervical radiculopathy or myelopathy. Neutral, flexion, and extension radiographs of the cervical spine obtained before surgery, and at 3, 6, and 12 months after surgery were assessed. Quantitative assessments and comparisons of motion patterns were produced using validated computer-assisted methods. Kinematic parameters, including segmental rotation, translation, center of rotation (COR), disc height, and disc angle were calculated. Cervical TDR preserved angular motion at the operated level, although the range was reduced from 8.0° before surgery to 6.2° at 12 months after surgery (P < 0.001). Significantly after TDR, adjacent-level angular motion was unchanged. In patients treated with fusion, angular motion at the superior adjacent level increased from 9.6° before surgery to 11.0° (P = 0.003) at 12 months, with a trend toward increased postoperative translation (P = 0.07). For the TDR group, the horizontal COR averaged 0.8 mm posterior to the disc center before surgery and 0.2 mm anterior to the center at 12 months after TDR (P < 0.001), and the vertical COR averaged 2.5 mm below the endplate before surgery and 4.0 mm below at 12 months (P = 0.001). COR at the adjacent levels was unaltered by fusion or TDR. Lordotic alignment and disc height at the index level increased after intervention in both groups. TDR with the porous coated motion implant is able to restore and maintain lordotic alignment and disc height and maintain angular motion while allowing for similar translation to that seen before surgery. In contrast, after ACDF, the superior adjacent level developed increased angular motion compared with preoperative range of motion. This study provides in vivo data regarding the functioning of TDR and ACDF and their impact on adjacent-level kinematics.

Commentary on an article by Rick Delamarter, MD, et al.

For nearly as long as spinal arthrodesis has been used to treat lumbar spine disorders, concerns have been raised regarding the long-term biomechanical and anatomic ramifications of successful fusion, particularly adjacent-segment disc degeneration and loss of lumbar range of motion. In many ways, the specter of adjacent-segment disc degeneration has been most concerning as it can lead to a deterioration in function that was gained following the initial procedure as well as to symptoms that may require further surgery. As a result, new surgical devices and procedures are being developed with the intention of treating lumbar degenerative conditions while maintaining near-normal biomechanical and anatomic parameters. Without question, the total disc replacement is one such “motion-sparing” device that has received substantial attention within the spine surgery community. Despite the fact that total disc replacement has been performed in Europe since the mid-1980s, there have been few scientifically rigorous investigations capable of providing high-grade evidence regarding optimal indications, effectiveness, and longevity1,2. Recently, randomized prospective studies on the short-term benefits of single-level total disc replacement have demonstrated that the beneficial results of this procedure have been maintained for up to five years following surgery1,2. Yet, until now, no comparable investigation was available regarding the use of total disc replacement as treatment for lumbar degenerative disorders at two contiguous levels. The authors of the present study are to …

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

current lumbar total disc replacement (TDR) devices require an anterior approach for implantation. This approach has inherent limitations, including risks to abdominal structures and the need for resection of the anterior longitudinal ligament (ALL). Placement of a TDR device from a true lateral (extreme lateral interbody fusion [XLIF]) approach is thought to offer a less invasive option to access the disc space, preserving the stabilizing ligaments and avoiding scarring of anterior vasculature. In this study, the authors attempted to quantify the clinical and radiographic outcomes of a lateral approach to lumbar TDR from a prospective, single-center experience. a TDR device designed for implantation through a true lateral, retroperitoneal, transpsoas approach (XLIF) was implanted in 36 patients with discography-confirmed 1- or 2-level degenerative disc disease. Clinical (pain and function) and radiographic (range of motion [ROM]) data were prospectively collected preoperatively, postoperatively, and serially for a minimum of 24 months' follow-up. thirty-six surgeries were performed in 16 men and 20 women (mean age 42.6 years). Surgeries included 15 single-level TDR procedures at L3-4 or L4-5, three 2-level TDR procedures spanning L3-4 and L4-5, and 18 hybrid procedures (anterior lumbar interbody fusion [ALIF]) at L5-S1 and TDR at L4-5 [17] or L3-4 [1]). Operative time averaged 130 minutes, with an average blood loss of 60 ml and no intraoperative complications. Postoperative radiographs showed good device placement. All patients were walking within 12 hours of surgery and all but 9 were discharged the next day (7 of 9 had hybrid TDR/ALIF procedures). Five patients (13.8%) had psoas weakness and 3 (8.3%) had anterior thigh numbness postoperatively, both resolving within 2 weeks. One patient (2.8%) demonstrated weakness of the leg ipsilateral to the approach side, which lasted through the 3-month visit but was resolved by the 6-month visit. One patient (2.8%) was found to have hypertrophy of the quadriceps contralateral to the approach side at the 12-month visit, which was resolved by the 2-year visit. Four patients (11%) had postoperative facet joint pain, all in hybrid cases. All patients were 2 years or more postsurgery as of this writing, although 3 were lost to follow-up between the 1- and 2-year visits. In 2 cases (5.6%), removal of the TDR device and revision to fusion were required due to unresolved pain. At 2 years' follow-up, the average visual analog scale and Oswestry Disability Index scores had improved 69.6% and 61.4%, respectively, and ROM averaged 8.6°, well within physiological norms. long-term results of a laterally placed TDR device demonstrate maintenance of pain relief and functional improvement. The benefits of this technique-minimal morbidity, avoiding mobilization of the great vessels, preserving the ALL, biomechanically stable orientation, and broader revision options-suggest a promising new direction for TDR procedures.

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 single-level cases.

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

BackgroundFusion 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.MethodsThis 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.ResultsOperative 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.ConclusionsPatients 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 RelevanceThis study suggests that 2-level TDR can be undertaken in appropriately selected patients and achieve results similar to singlelevel cases.

The Effect of Lumbar Total Disc Replacement on the Spinopelvic Alignment and Range of Motion of the Lumbar Spine

A lumbar total disc replacement (TDR) is a type of motion-preserving surgery, which aims to restore and maintain the normal range of motion (ROM) and the sagittal balance of the spine. However, little is known regarding how the spinopelvic alignment and ROM of the lumbar spine are influenced by the lumbar TDR with ProDisc. This study retrospectively analyzed the sagittal alignment and ROM of the lumbar spine in 26 consecutive patients who had undergone the TDR with ProDisc with a minimum follow-up of 24 months. A standing lateral radiograph, which included the femoral heads and dynamic flexion-extension lateral radiographs of the spine were taken before surgery and at the follow-up visit. The radiological parameters included the sacral tilt, the pelvic tilt, and the lumbar lordosis. The segmental lordosis and ROM were also measured at each operative level. Nineteen patients underwent a single-level TDR and 7 patients underwent a double-level TDR. The mean lumbar lordosis increased significantly from 30.5 degrees to 40.8 degrees in all patients who underwent TDR without any significant changes in the sacral tilt and pelvic tilt at the latest follow-up (P<0.05). In the patients who underwent single-level TDR, the mean segmental lordosis at the L5-S1 and L4-5 operative levels increased significantly from 15.8 degrees to 23.2 degrees and from 14.1 degrees to 24.9 degrees, respectively. The mean ROM at L5-S1 and L4-5 increased significantly from 7.1 degrees to 11.2 degrees and from 11.4 degrees to 14.6 degrees, respectively. The sagittal balance and ROM of the lumbar spine improved significantly after the lumbar TDR.