The effect of interlaminar Coflex stabilization in the topping-off procedure on local and global spinal sagittal alignment.

PURPOSE: To investigate the effect of interlaminar Coflex stabilization (ICS) at various segments in the topping-off procedure on local and global spinal sagittal alignment. METHODS: Eighty-nine consecutive patients with degenerative lumbar spinal stenosis (DLSS) who underwent ICS and transforaminal lumbar interbody fusion (TLIF) were retrospectively reviewed. They were divided into Group A (L4-L5 ICS + L5-S1 TLIF), Group B (L3-L4 ICS + L4-S1 TLIF), and Group C (L2-L3 ICS + L3-S1 TLIF) according to their fusion levels. The measured local sagittal parameters included the implanted segmental angle (ISA), intervertebral disc angle (IDA), intervertebral foreman height (IFH), and disc height. The assessed global sagittal parameters included thoracic kyphosis, lumbar lordosis (LL), the fused segment angle (FSA), the sacral slope, the pelvic tilt, pelvic incidence, and the sagittal vertical axis. The Oswestry Disability Index (ODI) and visual analog scales (VAS) were recorded to evaluate the clinical outcomes. RESULTS: Regarding the local alignment parameters, the ISA and IDA decreased immediately after surgery in Groups A and B, followed by an increase at the last follow-up (all, P < 0.05). Conversely, the IFH of Groups A and B first increased after surgery and then decreased to approximately the original value (all, P < 0.05). No significant differences were evident between the local sagittal parameters at different time points in Group C. Regarding the global sagittal profiles, the LL and FSA exhibited a significant postoperative increase (both at P < 0.05) in all the groups. All three groups displayed significant improvements in the ODI, VAS-back pain, and VAS-leg pain. Furthermore, 4.5% (4/89) of the patients exhibited radiographic adjacent segment degeneration (ASD) at the last follow-up. CONCLUSION: ICS during topping-off surgery led to a temporary loss of local lordosis, especially in the lower lumbar segment, while the intervertebral space realigned after middle-term follow-up. The topping-off procedure with ICS is a feasible and promising surgical option of DLSS since it reduces fusion levels and prevents ASD development.

Risk of adjacent segment disease after 'topping-off' multi-level lumbar fusions with posterior dynamic stabilisers: an observational cohort study.

PURPOSE: To determine whether 'topping-off' lumbar fusions, using posterior dynamic stabilising devices (PDSs) with specific biomechanical parameters, reduces the risk of adjacent segment disease (ASD). METHODS: Survival analysis of two non-randomised cohorts, with or without 'topping-off' (T/O or NoT/O), compared the risk of further surgery for ASD following multi-level posterior lumbar interbody fusion (PLIF). The study sample comprised consecutive patients, aged 55 + years, with degenerative pathology at 2, 3 or 4 levels. The NoT/O cohort underwent surgery between August 1993 and September 2019 (n = 425) and the T/O cohort between September 2011 and September 2019 (n = 146). Comparison of ASD risk between cohorts used Cox proportional hazards (CPH) modelling and Kaplan-Meier survivorship analysis. RESULTS: Analysis was completed on 571 operations across 507 patients. Median follow-up was 63 months (range 0.3-196) and 37 months (range 1.7-98) for the NoT/O and T/O cohorts, respectively. Of 423 patients, 125 (29.6%) patients in the NoT/O cohort underwent further surgery for ASD and 16/145 (11.03%) in the T/O cohort. The hazard ratio (T/O: NoT/O) from the CPH model was 0.42 (95% CL: 0.24-0.74, P = 0.003). Mean annual incidence across the first 5 years was 5.0% in the NoT/O cohort compared with 2.8% in the T/O cohort (P = 0.029). No patient required surgery or developed ASD at a 'topped-off' level. Two patients developed asymptomatic pedicle screw loosening at the level of the PDS device. PROMs were similar between cohorts. CONCLUSION: This large, non-randomised, observational study found an approximately 60% reduction in further surgery for ASD with the use of the PDS to 'top-off' PLIF fusions. PDS device-related complications were very low.

Biomechanical changes of degenerated adjacent segment and intact lumbar spine after lumbosacral topping-off surgery: a three-dimensional finite element analysis.

BACKGROUND: Previous studies have revealed positive effect of Topping-off technique on upper adjacent segment after fusion surgery, while for the cases with fusion surgery on L5-S1 segment, owning maximal range of motion, and preexisting degenerated upper adjacent disc, it is necessary to clarify the superiority of Topping-ff technique and the effect exerted on the lumbar spine. METHODS: A young healthy male volunteer was selected for thin-slice CT scanning. Then the image information was imported into the computer to establish the whole lumbar spine model as the health model. The medium degeneration model of intervertebral disc was established by changing the material properties of L4-S1 disc on the basis of the health model, and the fusion model and Topping-off model were respectively established on the basis of the degenerated model. The variation trend of ROM of L2-L5 and the stress changes of L4-L5 intervertebral disc, nucleus pulposus and facet joints were calculated respectively. RESULTS: The L4-L5 ROM of fusion model increased significantly but the ROM of L2-L3 and L3-L4 segments did not change significantly. Compared with the degenerated model, L4-L5 activity of the Topping-off model decreased, and ROM of the L2-L3 and L3-L4 increased to some extent in the flexion and extension positions. The stress on the disc, nucleus pulposus and facet joint of the fusion model L4-L5 increased in four positions of flexion, extension, rotation and bending compared with the degenerated model, while the fiber stress on the Topping-off model decreased significantly in all four positions. CONCLUSION: Topping-off technology can decrease the stress and ROM of the adjacent upper degenerated segment, and increase the ROM of other upper segments, thereby protecting the degenerated upper adjacent segments and compensating the lumbar spine mobility.

Biomechanical investigation of lumbar hybrid stabilization in two-level posterior instrumentation.

PURPOSE: Hybrid stabilization with a dynamic implant has been suggested to avoid adjacent segment disease by creating a smoother transition zone from the instrumented segments to the untreated levels above. This study aims to characterize the transition zones of two-level posterior instrumentation strategies for elucidating biomechanical differences between rigid fixation and the hybrid stabilization approach with a pedicle screw-based dynamic implant. METHODS: Eight human lumbar spines (L1-5) were loaded in a spine tester with pure moments of 7.5 Nm and with a hybrid loading protocol. The range of motion (ROM) of all segments for both loading protocols was evaluated and normalized to the native ROM. RESULTS: For pure moment loading, ROM of the segments cranial to both instrumentations were not affected by the type of instrumentation (p > 0.5). The dynamic instrumentation in L3-4 reduced the ROM compared to intact (p < 0.05) but allowed more motion than the rigid fixation of the same segment (p < 0.05). Under hybrid loading testing, the cranial segments (L1-2, L2-3) had a significant higher ROM for both instrumentations compared to the intact (p < 0.05). Comparing the two instrumentations with each other, the rigid fixation resulted in a higher increased ROM of L1-2 and L2-3 than hybrid stabilization. CONCLUSIONS: Regardless of the implant, two-level posterior instrumentation was accompanied by a considerable amount of compensatory movement in the cranial untreated segments under the hybrid protocol. Hybrid stabilization, however, showed a significant reduction of this compensatory movement in comparison to rigid fixation. These results could support the surgical strategy of hybrid stabilization, whereas the concept of topping-off, including a healthy segment, is discouraged.

[Hybrid stabilization technique with spinal fusion and interlaminar device to reduce the length of fusion and to protect symptomatic adjacent segments : Clinical long-term follow-up]. / Hybridversorgung mit Fusion und interlaminärem Implantat zur Verkürzung der Spondylodesestrecke und Protektion der symptomatischen Anschlussdegeneration : Klinisches Langzeit-Follow-up.

INTRODUCTION: Determination of the extent of spinal fusion for lumbar degenerative diseases is often difficult due to minor pathologies in the adjacent segment. Although surgical intervention is required, fusion seems to be an overtreatment. Decompression alone may be not enough as this segment is affected by multiple factors such as destabilization, low grade degeneration and an unfavorable biomechanical transition next to a rigid construct. An alternative surgical treatment is a hybrid construct, consisting of fusion and implantation of an interlaminar stabilization device at the adjacent level. The aim of this study was to compare long-term clinical outcome after lumbar fusion with a hybrid construct including an interlaminar stabilization device as "topping-off". MATERIALS AND METHODS: A retrospective analysis of 25 lumbar spinal fusions from 2003 to 2010 with additional interlaminar stabilization device was performed. Through a matched case controlled procedure 25 congruent patients who received lumbar spinal fusion in one or two levels were included as a control group. At an average follow-up of 43 months pre- and postoperative pain, ODI, SF-36 as well as clinical parameters, such as leg and back pain, walking distance and patient satisfaction were recorded. RESULTS: Pain relief, ODI improvement and patient satisfaction was significantly higher in the hybrid group compared to the control group. SF-36 scores improved in both groups but was higher in the hybrid group, although without significance. Evaluation of walking distance showed no significant differences. DISCUSSION: Many outcome parameters present significantly better long-term results in the hybrid group compared to sole spinal fusion. Therefore, in cases with a clear indication for lumbar spinal fusion with the need for decompression at the adjacent level due to spinal stenosis or moderate spondylarthrosis, support of this segment with an interlaminar stabilization device demonstrates a reasonable treatment option with good clinical outcome. Also, the length of the fusion construct can be reduced allowing for a softer and more harmonic transition.

The effects of topping-off instrumentation on biomechanics of sacroiliac joint after lumbosacral fusion.

BACKGROUND: Lumbar/lumbosacral fusion supplemented with topping-off devices has been proposed with the aim of avoiding adjacent segment degeneration proximal to the fusion construct. However, it remains unclear how the biomechanics of the sacroiliac joint (SIJ) are altered after topping-off surgery. The objective of this study was to investigate the biomechanical effects of topping-off instrumentation on SIJ after lumbosacral fusion. METHODS: The validated finite element model of an intact lumbar spine-pelvis segment was modified to simulate L5-S1 interbody fusion fixed with a pedicle screw system. An interspinous spacer, Device for Intervertebral Assisted Motion (DIAM), was used as a topping-off device and placed between interspinous processes of the L4 and L5 segments. Range of motion (ROM), von-Mises stress distribution, and ligament strain at SIJ were compared between fusion (without DIAM) and topping-off (fusion with DIAM) models under moments of four physiological motions. RESULTS: ROM at the left and right SIJs in the topping-off model was higher by 26.9% and 27.5% in flexion, 16.8% and 16.1% in extension, 18.8% and 15.8% in lateral bending, and 3.7% and 7.4% in axial rotation, respectively, compared to those in the fusion model. The predicted stress and strain data showed that under all physiological loads, the topping-off model exhibited higher stress and ligament strain at the SIJs than the fusion model. CONCLUSIONS: Motion, stress, and ligament strain at SIJ increase when supplementing lumbosacral fusion with topping-off devices, suggesting that topping-off surgery may be associated with higher risks of SIJ degeneration and pain than fusion alone.

[Clinical study on modified Topping-off technology in the treatment of multiple lumbar degenerative diseases].

OBJECTIVE: To explore the clinical effect of the modified Topping-off technique in the treatment of multiple lumbar degenerative diseases. METHODS: From October 2019 to May 2020, 42 patients who underwent modified Topping-off operation (modified Topping-off group) and 42 patients who underwent multilevel total laminectomy and interbody fusion with screw rod system internal fixation (whole laminectomy group) were observed and analyzed. There were 15 males and 27 females in the modified Topping-off group, aged from 28 to 80 years old, with an average of (59.57±11.85)years old. There were 14 males and 28 females in the whole laminectomy group, aged from 45 to 82 years old, with an average of (64.26±9.19) years old. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were evaluated before operation, 1 week, 6 weeks and 12 weeks after operation. The intraoperative blood loss, incision length, operation time, postoperative drainage, weight-bearing time, hospitalization time, intervertebral space height, intervertebral foramen height and lumbar mobility were statistically analyzed. RESULTS: All patients were followed up for 12 weeks. The intraoperative blood loss and postoperative drainage in the modified Topping-off group were significantly less than those in the whole lamina group (P<0.05). The incision length, operation time, weight-bearing time and hospital stay in the modified Topping-off group were shorter than those in the whole lamina group(P<0.05). There were significant differences in intervertebral space height, intervertebral foramen height and lumbar mobility between the two groups at 12 weeks after operation(P<0.05). The modified Topping-off group had significantly lower VAS 1, 6, 12 weeks after operation and ODI 12 weeks after operation compared with rhose before operation. The VAS at 1, 6, 12 weeks in the whole lamina group were significantly lower those that before operation(P<0.05). The ODI at 12 weeks in the whole lamina group were significantly lower than those before operation(P<0.01). There were significant differences in VAS scores between the two groups at 1 week, 6 weeks and 12 weeks after operation(P<0.01). There was significant difference in ODI between the two groups 12 weeks after operation(P<0.01). CONCLUSION: The application of modified Topping-off technique in the treatment of multi segmental lumbar degenerative diseases can reduce the total length of fusion segments, avoid or slow down the degeneration of adjacent segments, and has a positive effect on maintaining the normal movement of the spine.

Comparison of long-term outcomes of spinal fusion surgeries supplemented with "topping-off" implants in lumbar degenerative diseases: A systematic review and network meta-analysis.

Background Context: Spinal fusion surgery is a common treatment for lumbar degenerative diseases and has been associated with the long-term complication of adjacent segment disease (ASD). In recent years, the "topping-off" technique has emerged as a new surgical method, combining spinal fusion with a hybrid stabilization device (HSD) or interspinous process device (IPD) proximal to the fused vertebrae. Methods: A literature search using the PubMed, Cochrane Central Register of Controlled Trials, EMBASE, and Web of Science databases identified eligible studies comparing topping-off implant(s) with spinal fusion surgery for lumbar degenerative diseases. Risk of bias was assessed using the Cochrane RoB 2.0 tool for randomized controlled trials and the Newcastle-Ottawa scale for retrospective studies. Each outcome was analyzed using the statistical Confidence in NMA (CINeMA) 1.9.0 software. Results: 17 RCTs and retrospective studies that included 1255 participants and five interventions were identified. The topping-off implants device for intervertebral assisted motion (DIAM; OR = 0.235, p < 0.001), Dynesys (OR = 0.413, p < 0.001), and Coflex (OR = 0.417, p < 0.01) significantly lowered the incidence of radiographic adjacent segment degeneration (RASDeg) compared with spinal fusion surgery alone. Spinal fusion supplemented with DIAM significantly reduced the incidence of clinical adjacent segment disease (CASD) (OR = 0.358, p = 0.032). Conclusions: Spinal fusion supplemented with DIAM substantially reduced the incidence of radiographic and clinical adjacent segment disease. No significant difference was observed between the treatment comparators for reoperation due to ASD and back pain relief score.

Instrumentation Techniques to Prevent Proximal Junctional Kyphosis and Proximal Junctional Failure in Adult Spinal Deformity Correction: A Systematic Review of Clinical Studies.

STUDY DESIGN: Systematic review. OBJECTIVES: To summarize the results of clinical studies investigating spinal instrumentation techniques aiming to reduce the postoperative incidence of proximal junctional kyphosis (PJK) and/or failure (PJF) in adult spinal deformity (ASD) patients. METHODS: EMBASE and Medline® were searched for articles dating from January 2000 onward. Data was extracted by 2 independent authors and methodological quality was assessed using ROBINS-I. RESULTS: 18 retrospective- and prospective cohort studies with a severe or critical risk of bias were included. Different techniques were applied at the upper instrumented vertebra (UIV): tethers in various configurations, 2-level prophylactic vertebroplasty (2-PVP), transverse process hooks (TPH), flexible rods (FR), sublaminar tapes (ST) and multilevel stabilization screws (MLSS). Compared to a pedicle screw (PS) group, significant differences in PJK incidence were found using tethers in various configurations (18% versus 45%, P = 0.001, 15% versus 38%, P = 0.045), 2-PVP (24% vs 36%, P = 0.020), TPH (0% vs. 30%, P = 0.023) and FR (15% versus 38%, P = 0.045). Differences in revision rates for PJK were found in studies concerning tethers (4% versus 18%, P = 0.002), 2-PVP (0% vs 13%, P = 0.031) and TPH (0% vs 7%, P = n.a.). CONCLUSION: Although the studies are of low quality, the most frequently studied techniques, namely 2-PVP as anterior reinforcement and (tensioned) tethers or TPH as posterior semi-rigid fixation, show promising results. To provide a reliable comparison, more controlled studies need to be performed, including the use of clinical outcome measures and a uniform definition of PJF.

Biomechanical investigation of topping-off technique using an interspinous process device following lumbar interbody fusion under vibration loading.

Topping-off technique has been proposed to prevent adjacent-segment degeneration/disease following spine fusion surgery. Nevertheless, few studies have investigated biomechanics of the fusion surgery with topping-off device under whole-body vibration (WBV). This biomechanical study aimed to investigate the vibration characteristics of human lumbar spine after topping-off surgery, and also to evaluate the effect of bony fusion on spine biomechanics. Based on a healthy finite-element model of lumbosacral spine (L1-sacrum), the models of topping-off surgery before and after bony fusion were developed. The simulated surgical procedures consisted of interbody fusion with rigid stabilizer at L4-L5 segment (rigid fusion) and dynamic stabilizer at degenerated L3-L4 segment. An interspinous implant, Device for Intervertebral Assisted Motion (DIAM, Medtronic Inc., Minnesota, USA), was used as the dynamic stabilizer. The stress responses of spine segments and implants under a vertical cyclic load were calculated and analyzed. The results showed that compared with rigid fusion alone, the topping-off technique significantly decreased disc stress at transition segment (L3-L4) as expected, and resulted in a slight increase in disc stress at its supra-adjacent segment (L2-L3). It indicated that the topping-off stabilization using DIAM might provide a good tradeoff between protection of transition segment and deterioration of its supra-adjacent segment during WBV. Also, it was found that bony fusion decreased stress in L4 inferior endplate and rigid stabilizer but had nearly no effect on stress in DIAM and L3-L4 disc, which was helpful to determine the biomechanical differences before and after bony fusion.

Biomechanical comparison of semirigid junctional fixation techniques to prevent proximal junctional failure after thoracolumbar adult spinal deformity correction.

BACKGROUND CONTEXT: Adult spinal deformity patients treated operatively by long-segment instrumented spinal fusion are prone to develop proximal junctional kyphosis (PJK) and failure (PJF). A gradual transition in range of motion (ROM) at the proximal end of spinal instrumentation may reduce the incidence of PJK and PJF, however, previously evaluated techniques have not directly been compared. PURPOSE: To determine the biomechanical characteristics of five different posterior spinal instrumentation techniques to achieve semirigid junctional fixation, or "topping-off," between the rigid pedicle screw fixation (PSF) and the proximal uninstrumented spine. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Seven fresh-frozen human cadaveric spine segments (T8-L3) were subjected to ex vivo pure moment loading in flexion-extension, lateral bending and axial rotation up to 5 Nm. The native condition, three-level PSF (T11-L2), PSF with supplemental transverse process hooks at T10 (TPH), and two sublaminar taping techniques (knotted and clamped) as one- (T10) or two-level (T9, T10) semirigid junctional fixation techniques were compared. The ROM and neutral zone (NZ) of the segments were normalized to the native condition. The linearity of the transition zones over three or four segments was determined through linear regression analysis. RESULTS: All techniques achieved a significantly reduced ROM at T10-T11 in flexion-extension and axial rotation relative to the PSF condition. Additionally, both two-level sublaminar taping techniques (CT2, KT2) had a significantly reduced ROM at T9-T10. One-level clamped sublaminar tape (CT1) had a significantly lower ROM and NZ compared with one-level knotted sublaminar tape (KT1) at T10-T11. Linear regression analysis showed the highest linear correlation between ROM and vertebral level for TPH and the lowest linear correlation for CT2. CONCLUSIONS: All studied semirigid junctional fixation techniques significantly reduced the ROM at the junctional levels and thus provide a more gradual transition than pedicle screws. TPH achieves the most linear transition over three vertebrae, whereas KT2 achieves that over four vertebrae. In contrast, CT2 effectively is a one-level semirigid junctional fixation technique with a shift in the upper rigid fixation level. Clamped sublaminar tape reduces the NZ greatly, whereas knotted sublaminar tape and TPH maintain a more physiologic NZ. Clinical validation is ultimately required to translate the biomechanics of various semirigid junctional fixation techniques into the clinical goal of reducing the incidence of proximal junctional kyphosis and failure. CLINICAL SIGNIFICANCE: The direct biomechanical comparison of multiple instrumentation techniques that aim to reduce the incidence of PJK after thoracolumbar spinal fusion surgery provides a basis upon which clinical studies could be designed. Furthermore, the data provided in this study can be used to further analyze the biomechanical effects of the studied techniques using finite element models to better predict their post-operative effectiveness.

Adjacent segment degeneration and topping off. Never stop at the apex!

We investigated if applying the Transition system (Globus Medical Inc., Audubon, PA, USA) as topping off can prevent Adjacent Segment Degeneration (ASD) and if rate of ASD is increased if instrumentation stopped at the apex of the Lumbar Lordosis (LL). We enrolled 99 consecutive patients in a retrospective study who have been operated by instrumented fusion of the lumbar spine. Thirty patients were treated by topping of (Group 1), 69 patients received the standard procedure (Group 2). 18 patients of group 1 (60%) and 38 patients of group 2 (55%) developed ASD. The difference was not significant (P>0.05). In 17 patients (17%) instrumentation stopped at apex of LL. 14/17 patients (82%) developed an ASD. This influence was significant (P<0.05). Instrumented fusion of the lumbar spine should not stop at the apex of the lumbar curve. Topping off by hybrid dynamic fixation does not reduce the rate of ASD.

Topping-off surgery vs posterior lumbar interbody fusion for degenerative lumbar disease: a comparative study of clinical efficacy and adjacent segment degeneration.

BACKGROUND: Studies have shown that adjacent segment degeneration (ASD) is a common complication after posterior lumbar interbody fusion (PLIF), even a second surgery is required for some patients. It remains unclear whether the non-fusion surgery can relieve ASD. Therefore, this study aims to investigate the clinical outcomes of Topping-off surgery (fusion combined with Coflex) and PLIF for degenerative lumbar disease (DLD) and the efficacy on preventing ASD. METHOD: A retrospective analysis was performed on the clinical data of 99 patients with DLD from January 2011 to December 2014, who were performed by Topping-off surgery (L4-5 PLIF + L3-4 Coflex, n = 45) or PLIF (L3-5 PLIF, n = 54). All patients included in the analysis had a minimum of 3 years of follow-up. Clinical data were used to assess the clinical efficacy, and radiographic parameters were measured for evaluation of the incidence of ASD. RESULTS: The mean ages of Topping-off group and PLIF group were 53.5 and 65.7 years old, respectively (P < 0.05). The surgical time, intraoperative blood loss, Oswestry disability index (ODI), and visual analog scale (VAS) were significantly different between the two groups (P < 0.05). Intervertebral mobility (L2-L3) of the Topping-off group was not changed significantly at 3 years after surgery than before (P > 0.05), while that of PLIF group was increased considerably (P < 0.05). As to intergroup comparison, intervertebral mobility (L2-L3) of Topping-off group was superior to those of the PLIF group (P < 0.05). Surprisingly, there was no significant difference in the general adjacent segment mobility (GASM) at L2-4 of the Topping-off group and intervertebral mobility (L2-L3) of PLIF group at 3 years after surgery (P > 0.05). Lumbar MRI at three post-operative years indicated that the modified Pfirrman grading of disc (L2-L3) in the Topping-off group was much better than that of the PLIF group (P < 0.05). CONCLUSION: This study showed that Topping-off surgery had the benefits of less invasiveness, less bleeding, and comparable clinical efficacy as PLIF for DLD. The segment with Coflex insertion undertook part of the mobility and stress in the proximal lumbar spine, which is conducive to alleviating ASD.

Topping-off technique for stabilization of lumbar degenerative instabilities in 322 patients.

OBJECTIVE: Semi-rigid instrumentation (SRI) was introduced to take advantage of the concept of load sharing in surgery for spinal stabilization. The authors investigated a topping-off technique in which interbody fusion is not performed in the uppermost motion segment, thus creating a smooth transition from stabilized to free motion segments. SRI using the topping-off technique also reduces the motion of the adjacent segments, which may reduce the risk of adjacent segment disease (ASD), a frequently observed sequela of instrumentation and fusion, but this technique may also increase the possibility of screw loosening (SL). In the present study the authors aimed to systematically evaluate reoperation rates, clinical outcomes, and potential risk factors and incidences of ASD and SL for this novel approach. METHODS: The authors collected data for the first 322 patients enrolled at their institution from 2009 to 2015 who underwent surgery performed using the topping-off technique. Reoperation rates, patient satisfaction, and other outcome measures were evaluated. All patients underwent pedicle screw-based semi-rigid stabilization of the lumbar spine with a polyetheretherketone (PEEK) rod system. RESULTS: Implantation of PEEK rods during revision surgery was performed in 59.9% of patients. A median of 3 motion segments (range 1-5 segments) were included and a median of 2 motion segments (range 0-4 segments) were fused. A total of 89.4% of patients underwent fusion, 73.3% by transforaminal lumbar interbody fusion (TLIF), 18.4% by anterior lumbar interbody fusion (ALIF), 3.1% by extreme lateral interbody fusion (XLIF), 0.3% by oblique lumbar interbody fusion (OLIF), and 4.9% by combined approaches in the same surgery. Combined radicular and lumbar pain according to a visual analog scale was reduced from 7.9 ± 1.0 to 4.0 ± 3.1, with 56.2% of patients indicating benefit from surgery. After maximum follow-up (4.3 ± 1.8 years), the reoperation rate was 16.4%. CONCLUSIONS: The PEEK rod concept including the topping-off principle seems safe, with at least average patient satisfaction in this patient group. Considering the low rate of first-tier surgeries, the presented results seem at least comparable to those of most other series. Follow-up studies are needed to determine long-term outcomes, particularly with respect to ASD, which might be reduced by the presented approach.

Posterior Lumbar Interbody Fusion versus Dynamic Hybrid Instrumentation: A Prospective Randomized Clinical Trial.

OBJECTIVE: The purpose of this study was to assess the radiologic and clinical outcomes after lumbar fusion intervention and to compare the established posterior lumbar interbody fusion (PLIF) technique and dynamic hybrid instrumentation (topping off). METHODS: In this prospective randomized trial, all patients who presented with degenerative changes to the lumbar spine (L2-S1) were included and randomized in 2 groups: patients who underwent the 360°-fusion procedure in PLIF (group 1: control group) and those patients who underwent fusion surgery with additional hybrid instrumentation (Dynesys-Transition-Optima [Zimmer Spine Inc., Denver, Colorado, USA]) cranial to the rigid fixed segment (group 2: intervention group). Patients' demographics were documented and follow-up visits were conducted after 6 weeks and then stepwise after 6 up to 36 months. Each follow-up visit included assessment of quality of life and pain using specific questionnaires (Core Outcome Measurements Index, Short-Form 36, and Oswestry Disability Index) as well as radiologic evaluation with the focus on the adjacent level alteration. RESULTS: Fifteen patients per group met the inclusion criteria, and after 36 months, the loss to follow-up was 20%. At the maximum follow-up time, the overall risk for adjacent segment degeneration was substantial (i.e., 24.14%), independent of the surgical procedure. Material failure was observed in 17.24%. Although no significant difference was observed between both groups, all patients presented with postoperative improvement regarding the clinical scores. CONCLUSIONS: The present study cannot support the safety of dynamic hybrid devices in those cases if the reduction of adjacent segment degeneration is the main target, especially regarding the reported implant failure rates and the similar clinical outcomes between the both groups.

Clinical experiences with a PEEK-based dynamic instrumentation device in lumbar spinal surgery: 2 years and no more.

BACKGROUND: Dynamic spine implants were developed to prevent adjacent segment degeneration (ASD) and adjacent segment disease (ASDi). Purpose of this study was to investigate the clinical and radiological outcomes of "topping off" devices following lumbar spinal fusion procedure using a PEEK-based dynamic rod system. Moreover, this study focused on the hypothesis that "topping off" devices can prevent ASD. METHODS: This prospective nonrandomized study included patients with indication for single-level lumbar fusion and radiological signs of ASD without instability. The exclusion criteria were previous lumbar spine surgery and no sign of disc degeneration in the adjacent segment according to magnetic resonance imaging. All patients were treated with single-level lumbar interbody fusion and dynamic stabilization of the cranial adjacent segment. Patients underwent a clinical examination and radiographs preoperatively and at 1 and 2 years after surgery. Analyses were performed on clinical data collected with the German Spine Registry using the core outcome measure index (COMI) and visual analogue scale (VAS) scores for back and leg pain. RESULTS: A total of 22 patients (6 male and 16 female) with an average age of 57.6 years were included in the study; 20 patients completed the follow-up (FU). The average COMI score was 9.0 preoperatively, 4.2 at the 1-year FU, and 4.7 at the 2-year FU. The average preoperative VAS scores for back and leg pain were 7.7 and 7.1, respectively. At the 1-year FU, the scores were 4.25 for back pain and 2.2 for leg pain, and at the 2-year FU, the scores were 4.7 for back pain and 2.3 for leg pain. At FU, failure of the dynamic topping off implant material was verified in four cases, and ASD of the segment cranial to the topping off was confirmed in three cases. CONCLUSIONS: These results demonstrate significant improvements in clinical outcomes and pain reduction after lumbar spinal fusion with topping off at 2 years after surgery. However, the implant failed due to the high rate of implant failure and the development of ASD in the segment cranial to the dynamic stabilized segment.

Biomechanical testing of a PEEK-based dynamic instrumentation device in a lumbar spine model.

BACKGROUND: The purpose of this study was to investigate the range-of-motion after posterior polyetheretherketone-based rod stabilisation combined with a dynamic silicone hinge in order to compare it with titanium rigid stabilisation. METHODS: Five human cadaveric lumbar spines with four vertebra each (L2 to L5) were tested in a temperature adjustable spine-testing set-up in four trials: (1) native measurement; (2) kinematics after rigid monosegmental titanium rod instrumentation with anterior intervertebral bracing of the segment L4/5; (3) kinematics after hybrid posterior polyetheretherketone rod instrumentation combined with a silicone hinge within the adjacent level (L3/4) and (4) kinematics after additional decompression with laminectomy of L4 and bilateral resection of the inferior articular processes (L3). During all steps, the specimens were loaded quasi-statically with 1°/s with pure moment up to 7.5Nm in flexion/extension, lateral bending and axial rotation. FINDINGS: In comparison to the native cadaveric spine, both the titanium device and polyetheretherketone-based device reduce the range-of-motion within the level L4/5 significantly (flexion/extension: reduction of 77%, p<0.001; lateral bending: reduction of 62%, p<0.001; axial rotation: reduction of 71%, p<0.001). There was a clear stabilisation effect after hybrid-instrumentation within the level L3/4, especially in flexion/extension (64%, p<0.001) and lateral bending (62%, p<0.001) but without any effect on the axial rotation. Any temperature dependency has not been observed. INTERPRETATION: Surprisingly, the hybrid device compensates for laminectomy L4 and destabilising procedure within the level L3/4 in comparison to other implants. Further studies must be performed to show its effectiveness regarding the adjacent segment instability.

Clinical study on modified Topping-off technology in the treatment of multiple lumbar degenerative diseases / 中国骨伤

OBJECTIVE@#To explore the clinical effect of the modified Topping-off technique in the treatment of multiple lumbar degenerative diseases.@*METHODS@#From October 2019 to May 2020, 42 patients who underwent modified Topping-off operation (modified Topping-off group) and 42 patients who underwent multilevel total laminectomy and interbody fusion with screw rod system internal fixation (whole laminectomy group) were observed and analyzed. There were 15 males and 27 females in the modified Topping-off group, aged from 28 to 80 years old, with an average of (59.57±11.85)years old. There were 14 males and 28 females in the whole laminectomy group, aged from 45 to 82 years old, with an average of (64.26±9.19) years old. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were evaluated before operation, 1 week, 6 weeks and 12 weeks after operation. The intraoperative blood loss, incision length, operation time, postoperative drainage, weight-bearing time, hospitalization time, intervertebral space height, intervertebral foramen height and lumbar mobility were statistically analyzed.@*RESULTS@#All patients were followed up for 12 weeks. The intraoperative blood loss and postoperative drainage in the modified Topping-off group were significantly less than those in the whole lamina group (P<0.05). The incision length, operation time, weight-bearing time and hospital stay in the modified Topping-off group were shorter than those in the whole lamina group(P<0.05). There were significant differences in intervertebral space height, intervertebral foramen height and lumbar mobility between the two groups at 12 weeks after operation(P<0.05). The modified Topping-off group had significantly lower VAS 1, 6, 12 weeks after operation and ODI 12 weeks after operation compared with rhose before operation. The VAS at 1, 6, 12 weeks in the whole lamina group were significantly lower those that before operation(P<0.05). The ODI at 12 weeks in the whole lamina group were significantly lower than those before operation(P<0.01). There were significant differences in VAS scores between the two groups at 1 week, 6 weeks and 12 weeks after operation(P<0.01). There was significant difference in ODI between the two groups 12 weeks after operation(P<0.01).@*CONCLUSION@#The application of modified Topping-off technique in the treatment of multi segmental lumbar degenerative diseases can reduce the total length of fusion segments, avoid or slow down the degeneration of adjacent segments, and has a positive effect on maintaining the normal movement of the spine.

Proximal junctional kyphosis and failure-diagnosis, prevention, and treatment.

Technical advancements have enabled the spinal deformity surgeon to correct severe spinal mal-alignment. However, proximal adjacent segment pathology (ASP) remains a significant issue. Examples include proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Agreement on the definition, classification, and pathophysiology of PJK and PJF remains incomplete, and an understanding of the risk factors, means of prevention, and treatment of this problem remains to be elucidated. In general, PJK is a relatively asymptomatic radiographic diagnosis managed with patient reassurance and monitoring. On the other hand, PJF is characterized by mechanical instability, pain, and more severe kyphosis, with potential for neurologic compromise. Patients who develop PJF more often require revision surgery than those with PJK. This chapter will review the current understanding of PJK and PJF.

Three-dimensional finite element analysis of the biomechanical changes of the lumbar spine after the combination of intervertebral fusion with dynamic internal fixation of the interspinous process in the lumbosacral region / 中国组织工程研究

BACKGROUND: The Topping-off technique, which combines lumbar fusion with the dynamic internal fixation system (Coflex), can not only reduce the pressure, but also protect the adjacent segments. There is no relevant mechanical analysis performed on the rationality of the application of Topping-off technique to young patients with the need for fusion on the lumbosacral region and adjacent degenerated segments. OBJECTIVE: To establish a finite element model of Topping-off surgery on the lumbosacral junction and to analyze the biomechanical changes of the adjacent segments and the range of motion trend of the lumbar spine. METHODS: A healthy young male volunteer with no previous history of low back pain or congenital malformations was randomly selected for thin-slice CT scanning after signed the informed consent. The image information was imported into the computer and the whole lumbar spine model as the healthy group model was established by analyzing the image information through Mimics, Geomagic Studio 12.0, HyperMesh and Abaqus successively. After verifying the effectiveness of the model, the moderate degeneration model of intervertebral disc was established by changing the material properties of L4-s1 discs on the basis of the healthy model, and the fusion model and Topping-off model were respectively established on the basis of the degeneration model. After applying 400 N compressive load and 10 N-m momentum to the four groups of models, the variation trends of range of motion from L2 to L5 and the stress changes of L4/L5 intervertebral disc, nucleus pulposus and facet joints were calculated respectively. RESULTS AND CONCLUSION: (1) Compared with the degeneration model, the lumbar range of motion of Topping-off model and fusion model decreased, and the Topping-off model decreased more significantly than the fusion model. (2) The range of motion of fusion model L4-L5 increased significantly and the range of motion of L2/L3 and L3/L4 segments did not change significantly. Compared with the degeneration model, the L4-L5 range of motion of Topping-off model decreased, and range of motion of the L2/L3 and L3/L4 levels increased to some extent in the flexion and extension positions. (3) Compared with the degeneration model, the stress on the disc, nucleus pulposus and facet joint of the fusion model L4-L5 increased in four positions of flexion, extension, rotation and bending, while the fiber stress on the Topping-off model decreased significantly in all four positions. (4) These results suggest that Topping-off technology can not only reduce the stress on the upper adjacent degenerative intervertebral disc, nucleus pulposus and facet joints, but also reduce the hyperactivity of the adjacent segments and increase the range of motion of other upper segments, thereby compensating the lumbar spine mobility and delaying the degeneration of upper adjacent segments.