Occurrence Of Adjacent Segment Degeneration Research Articles

The Impact of L4-L5 Minimally Invasive Transforaminal Lumbar Interbody Fusion on 2-Year Adjacent-level Parameters

ObjectiveThis study evaluates the impact of L4-5 minimally invasive surgery (MIS)-TLIF on adjacent-level parameters. MethodsThis is a retrospective study performed on consecutive patients between January 2015–December 2019. The index- and adjacent-level segmental lordosis (SL) and disc angle (DA) were measured. Patient-reported outcomes (PROs) were collected preoperatively and at 3–24 months postoperatively. Factors influencing changes in adjacent-level parameters and the occurrence of adjacent segment degeneration (ASDeg) were assessed. ResultsOne hundred and seventeen adult patients, averaging 65.5 years of age and slight preponderance of female (56.4%), were analyzed. L4-5 SL decreased at 2 years (p<0.05), but L4-5 DA significantly increased at all timepoints (p<0.05). While L3-4 SL and DA significantly decreased at all timepoints (p<0.05), L5-S1 SL decreased at 3 and 12 months (p<0.05) and L5-S1 DA only significantly decreased at 2 years (p<0.05). All PROs improved significantly (p<0.0001). The ASDeg rate was 19.7% at 2.2 years. Cephalad and caudal ASDeg rates were 12.0% and 10.3%, respectively. Eight patients (6.8%) required adjacent-level reoperations, mainly at L3-4 (6 cases). The use of expandable cage significantly reduced the odds of caudal ASDeg (OR 0.15, p=0.037), but had no significant effect on cephalad ASDeg.. ConclusionsL4-5 MIS-TLIF had a more consistent effect on L3-4 than L5-S1. Although adjacent-level SL and DA decreased over time, their association with ASDeg appears limited, suggesting a multifactorial etiology. L4-5 MIS-TLIF provides demonstrable clinical benefits with lasting PRO improvements and low adjacent-level reoperations.

Comparative analysis of risk factors associated with degeneration of adjacent segments: zero-profile anchored spacer vs. anterior cervical plate and cage construct.

Anterior cervical discectomy and fusion (ACDF) is an established treatment for cervical degenerative disc disease, but cervical spine surgery may affect sagittal alignment parameters and induce adjacent segment degeneration (ASD). This study aimed to determine the risk factors for developing ASD following anterior cervical plate and cage (ACPC) compared with the use of zero-profile anchored spacer (ROI-C). A retrospective contrastive study included 105 patients who underwent ACPC or ROI-C between January 2014 and October 2019 at our treatment centre. There were 50 cases in the ROI-C group and 55 patients in the ACPC group. Clinical and radiological results and the incidence of ASD were assessed after surgery. All patients were further divided into the ASD and non-ASD groups for subgroup analysis. At each follow-up time, there was no statistically significant in radiographic parameters between the two groups. The overall ASD rate was higher in the ACPC group than in the ROI-C group (65.5% vs. 44.0%, p = 0.027). The low preoperative Cobb angle, low preoperative segment angle (SA), and loss of Cobb (ΔCobb) were significantly correlated with ASD. However, clinical outcomes were not associated with ASD at any postoperative follow-up visit. Equally good therapeutic effects were achieved with both the ROI-C and ACPC. The occurrence of ASD was considerably higher in the ACPC group than in the ROI-C group. The preoperative Cobb angle, preoperative SA, and ΔCobb were the most associated with an increase in the risk of ASD.

Long-term Outcome of Isobar TTL System for the Treatment of Lumbar Degenerative Disc Diseases.

The Isobar TTL dynamic fixation system has demonstrated favorable outcomes in the short-term treatment of lumbar degenerative disc diseases (LDDs). However, there is a paucity of extensive research on the long-term effects of this system on LDDs. This study aimed to evaluate the long-term clinical and radiological outcomes of patients with LDDs who underwent treatment utilizing the Isobar TTL dynamic fixation system. The study analyzed the outcomes of 40 patients with LDDs who underwent posterior lumbar decompression and received single-segment Isobar TTL dynamic internal fixation at our hospital between June 2010 and December 2016. The evaluation of clinical therapeutic effect involved assessing postoperative pain levels using the visual analogue scale (VAS) and Oswestry disability index (ODI), both before surgery, 3 months after, and the final follow-up. To determine the preservation of functional motion in dynamically stable segments, we measured the range of motion (ROM) and disc height of stabilized and adjacent segments preoperatively and during the final follow-up. Additionally, we investigated the occurrence of adjacent segment degeneration (ASD). Forty patients were evaluated, with an average age of 44.65 years and an average follow-up period of 79.37 months. Fourteen patients belonged to the spondylolisthesis group, while the remaining 26 were categorized under the stenosis or herniated disc group. The preoperative ROM of the stabilized segment exhibited a significant reduction from 8.15° ± 2.77° to 5.00° ± 1.82° at the final follow-up (p < 0.001). In contrast, there was a slight elevation in the ROM of the adjacent segment during the final follow-up, increasing from 7.68° ± 2.25° before surgery to 9.36° ± 1.98° (p < 0.001). The intervertebral space height (IH) in the stabilized segment exhibited a significant increase from 10.56 ± 1.99 mm before surgery to 11.39 ± 1.90 mm at the one-week postoperative follow-up (p < 0.001). Conversely, there was a notable decrease in the IH of the adjacent segment from 11.09 ± 1.82 mm preoperatively to 10.86 ± 1.79 mm at the one-week follow-up after surgery (p < 0.001). The incidence of ASD was 15% (6/40) after an average follow-up period of 79.37 months, with a rate of 15.38% (4/26) in the stenosis or herniated disc group and 14.29% (2/14) in the spondylolisthesis group; however, no statistically significant difference was observed in the occurrence of ASD among these groups (p > 0.05). The Isobar TTL dynamic fixation system is an effective treatment for LDDs, improving pain relief, quality of life (QoL) and maintaining stabilized segmental motion. It has demonstrated excellent long-term clinical and radiographic results.

Biomechanical study of anterior transpedicular root screw intervertebral fusion system of lower cervical spine: a finite element analysis.

Background: The cervical anterior transpedicular screw (ATPS) fixation technology can provide adequate stability for cervical three-column injuries. However, its high risk of screw insertion and technical complexity have restricted its widespread clinical application. As an improvement over the ATPS technology, the cervical anterior transpedicular root screw (ATPRS) technology has been introduced to reduce the risk associated with screw insertion. This study aims to use finite element analysis (FEA) to investigate the biomechanical characteristics of a cervical spine model after using the novel ATPRS intervertebral fusion system, providing insights into its application and potential refinement. Methods: A finite element (FE) model of the C3-C7 lower cervical spine was established and validated. After two-level (C4-C6) anterior cervical discectomy and fusion (ACDF) surgery, FE models were constructed for the anterior cervical locked-plate (ACLP) internal fixation, the ATPS internal fixation, and the novel ATPRS intervertebral fusion system. These models were subjected to 75N axial force and 1.0 Nm to induce various movements. The range of motion (ROM) of the surgical segments (C4-C6), maximum stress on the internal fixation systems, and maximum stress on the adjacent intervertebral discs were tested and recorded. Results: All three internal fixation methods effectively reduced the ROM of the surgical segments. The ATPRS model demonstrated the smallest ROM during flexion, extension, and rotation, but a slightly larger ROM during lateral bending. Additionally, the maximum bone-screw interface stresses for the ATPRS model during flexion, extension, lateral bending, and axial rotation were 32.69, 64.24, 44.07, 35.89MPa, which were lower than those of the ACLP and ATPS models. Similarly, the maximum stresses on the adjacent intervertebral discs in the ATPRS model during flexion, extension, lateral bending, and axial rotation consistently remained lower than those in the ACLP and ATPS models. However, the maximum stresses on the cage and the upper endplate of the ATPRS model were generally higher. Conclusion: Although the novel ATPRS intervertebral fusion system generally had greater endplate stress than ACLP and ATPS, it can better stabilize cervical three-column injuries and might reduce the occurrence of adjacent segment degeneration (ASD). Furthermore, further studies and improvements are necessary for the ATPRS intervertebral fusion system.

Comparison of Long-term Follow-Up of n-HA PA66 Cage and PEEK Cage of Lumbar Interbody Fusion in Multi-level Degenerative Lumbar Diseases: A Stepwise Propensity Score Matching Analysis.

Previous studies have confirmed that the nanohydroxyapatite/polyamide-66 (n-HA/PA66) cage is an ideal alternative material for degenerative lumbar disease (DLD) comparable to the polyether ether ketone (PEEK) cage due to its similar radiographic fusion, subsidence rate, and clinical results. However, these studies were restricted to one-level surgery. The aim of this study was to analyze the long-term clinical and radiologic outcomes between n-HA PA66 cage and PEEK cage for patients with multi-level degenerative lumbar diseases (DLDs). We retrospectively reviewed all patients who underwent multi-level transforaminal lumbar interbody fusion (TLIF) from June 2010 to December 2016 with a minimum 6-year follow-up. Matched-pair analysis was performed using a 1-to-1 closest neighbor approach to match patients who received an n-HA PA66 cage with those who received a PEEK cage. Clinical outcomes and radiographic evaluations were compared between the two groups. The independent student's t-test and χ2 -test were applied to compare the differences between groups. At the end of the propensity score matching (PSM) analysis, 48 patients from n-HA/PA66 group were matched to 48 patients in the PEEK group. No significant difference was observed in cage subsidence and bony fusion except for adjacent segment degeneration (ASD). The occurrence of ASD was 14.58% (7/48) in the n-HA/PA 66 group, which was significantly less than that in the PEEK group (33.33% [16/48]) (p = 0.031). Although the intervertebral space height (IH), segmental angle (SA) and lumbar lordosis (LL) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). The visual analogue scale (VAS) and Oswestry disability index (ODI) scores significantly improved in both groups at 3m postoperative, 1y postoperative and at final follow-up. However, there were no significant differences in the VAS and ODI score at any time point (p > 0.05). The total complications and re-admission rate were not different between the two groups. Overall, our data suggest that the outcomes of n-HA/PA66 cage group are comparable to those of the PEEK cage group, with a similar high fusion rate and low cage subsidence rate as PEEK cages, except its lower rate of ASD occurrence.

Adjacent segment degeneration after single- and double-level cervical total disc replacement: a cohort with an over 12-year follow-up.

To characterize the change of adjacent segment degeneration (ASD) after cervical total disc replacement (CTDR) with more than 12-year follow-up, and identify the risk factors for ASD. This process included 75 patients underwent CTDR from February 2004 to December 2012, with the follow-up of 151.9 ± 36.0 (m). The artificial disc included ProDisc-C, Prestige-LP and Mobi-C. ASD was followed up at 1week, 6months, 1year, 2years, 5years, 10years after CTDR and at the endpoint of June 2022. The radiographic measurements were cervical mobility, intervertebral disc height (IDH), cervical lordosis and balance status. The complications were implant migration, subsidence and heterotopic ossification (HO). Cervical mobility in adjacent segments, IDH and lordosis showed no statistical differences between ASD and NASD group. Balance status, subsidence and migration showed no relationship with ASD. Postoperative ASD increased at 6m and especially between 6m to 2y. There was no difference between the incidence of upper ASD and lower ASD all the time and few ASD-related reoperation. The majority of adjacent segments were C4/5 (33.6%) and C6/7 (34.2%), and ASD of C5/6 had the highest incidence (61.5%). Cox regression showed ASD was not related to the types of prosthesis or operated numbers. Generalized estimating equations (GEE) analysis showed severe HO had a higher (2.68 times) probability to suffer from ASD. After over 12-year follow-up of CTDR, the occurrence of ASD and HO had temporal synchronization. ASD was not merely a natural progression but with the pathological process such as HO.

A Comparison of Corpectomy ACDF Hybrid Procedures with Nano-Hydroxyapatite/Polyamide 66 Cage and Titanium Mesh Cage for Multi-level Degenerative Cervical Myelopathy: A Stepwise Propensity Score Matching Analysis.

Previous studies have found satisfactory clinical results with the nano-hydroxyapatite/polyamide 66 (n-HA/PA66) cage to reconstruct the stability of anterior cervical column. However, studies evaluating the long-term outcomes of the n-HA/PA66 cage in multi-level degenerative cervical myelopathy (MDCM) have not been reported. This study aims to compare the outcomes of corpectomy anterior cervical discectomy and fusion (ACDF) hybrid procedures between the n-HA/PA66 cage and titanium mesh cage (TMC) to treat MDCM. After the screening for eligibility, this retrospective study involved 90 patients who underwent corpectomy ACDF hybrid (CACDFH) procedure from June 2013 to June 2018. The CACDFH procedure is the combination of ACDF and anterior cervical corpectomy and fusion (ACCF). According to the cage utilized, we categorized patients into a n-HA/PA66 cage group and a TMC group. Then, stepwise propensity score matching (PSM) was performed to maintain comparable clinical data between groups. All the patients were followed up ≥4 years and the longest follow-up time was 65.43 (±11.49) months. Cage subsidence, adjacent segment degeneration (ASD), segmental height (SH), segmental angle (SA), cervical lordosis (CL), and clinical data (visual analogue scale [VAS] and Japanese Orthopaedic Association [JOA] score) was evaluated preoperatively, at 1 week, and at the final surgery follow-up. The independent student's t test and chi-square test were applied to compare the differences between groups. Through PSM analysis, 25 patients from the n-HA/PA66 group were matched to 25 patients in the TMC group. The occurrence of ASD was 16.0% (4/25) in the n-HA/PA 66 group, which was significantly less than in the TMC group at 44.0% (11/25) (p = 0.031). Moreover, the cage subsidence rate was significantly higher in the TMC group as compared to the n-HA/PA 66 group (40.0% vs. 12.0%, p = 0.024). But there was no significant difference in SH, SA, and CL at any time after surgery as determined through follow-up. The VAS and JOA scores significantly improved in both groups at 3 months postoperative and at final follow-up. However, there were no significant differences in the VAS and JOA score at any time between the two groups in preoperative (p > 0.05). The n-HA/PA66 cage is associated with lower rate of cage subsidence and ASD than the TMC in the treatment of MDCM. The n-HA/PA66 cage could be superior to the TMC in corpectomy ACDF hybrid procedures.

Pelvic Incidence-Lumbar Lordosis Mismatch Is Predisposed to Adjacent Segment Degeneration After Single-Level Anterior Lumbar Interbody Fusion: A Retrospective Case-Control Study.

Spinopelvic parameters play important roles in clinical outcomes and disability after short-segment fusion surgery for degenerative spine disease. This study aimed to investigate the relationship between preoperative or postoperative spinopelvic parameters and symptomatic adjacent segment degeneration (ASD) after single-level anterior lumbar interbody fusion (ALIF) surgery at the L4-5 segments. All patients who underwent single-level ALIF at the L4-5 level from January 2010 to December 2013 and were followed up for 5 years were analyzed. We collected the degree of degeneration at adjacent segments and preoperative and postoperative spinopelvic parameters. We compared the preoperative and postoperative parameters between patients with and without symptomatic ASD. Sixty-one patients were included in our study, and 30 patients had symptomatic ASD. Degeneration at adjacent segments and preoperative spinopelvic parameters did not affect the occurrence of symptomatic ASD. Patients with symptomatic ASD had higher postoperative pelvic tilt (PT) and a mismatch between lumbar lordosis (LL) and pelvic incidence (PI) compared to those without. Postoperative PT > 15° and PI-LL mismatch > 10° were significant risk factors for symptomatic ASD. High PT and PI-LL mismatch were significant risk factors for symptomatic ASD after single-level ALIF surgery. Spine surgeons should consider achieving proper LL to insert the cage at the appropriate angle and prevent a PI-LL mismatch value > 10° after single-level fusion surgery.

Cervical Discometry: A Useful Technique for an Anterior Cervical Discectomy and Fusion.

Anterior cervical discectomy and fusion (ACDF), which is widely used in the treatment of cervical spondylosis, may cause complications such as adjacent segment degeneration (ASD). However, such studies on complications are limited, and quantitative evidence is still lacking. To evaluate the clinical value of cervical discometry combined with adjacent intraoperative intradiscal pressure in cervical vertebral surgery through clinical explorations. In this retrospective study, 100 patients who were treated with anterior decompression, reconstruction, and internal fixation, were enrolled. Among them, 50 patients received ACDF combined with perioperative pressure adjustment of the adjacent segments to ensure that the pressure difference was less than 5 mmHg. The other 50 patients who had only simple ACDF were considered as the control group. Patient information, radiographic changes, axial symptoms (AS), and the occurrence of ASD were recorded in the study. The degree of lordosis (D values) at postoperative of all cases were positive. The D value of the two groups of patients immediately after the operation and at the last follow-up were significantly higher than that before the operation (P < 0.05). The incidence of AS was significantly lower in the experimental group than that in the control group (P < 0.05). Besides, there were only 10 patients in the experimental group during the five-year follow-up period, which was significantly lower than the 19 patients in the control group (P < 0.05). The intraoperative intervertebral disc pressure measurement could effectively monitor the vertebral body distraction strength and reduce the incidence of postoperative AS and ASD.

Biomechanical Effect of Hybrid Dynamic Stabilization Implant on the Segmental Motion and Intradiscal Pressure in Human Lumbar Spine.

The hybrid dynamic stabilization system, Dynesys-Transition-Optima, represents a novel pedicle-based construct for the treatment of lumbar degenerative disease. The theoretical advantage of this system is to stabilize the treated segment and preserve the range of motion within the adjacent segment while potentially decreasing the risk of adjacent segment disease following lumbar arthrodesis. Satisfactory short-term outcomes were previously demonstrated in the Dynesys-Transition-Optima system. However, long-term follow-up reported accelerated degeneration of adjacent segments and segmental instability above the fusion level. This study investigated the biomechanical effects of the Dynesys-Transition-Optima system on segment motion and intradiscal pressure at adjacent and implanted levels. Segmental range of motion and intradiscal pressure were evaluated under the conditions of the intact spine, with a static fixator at L4-5, and implanted with DTO at L3-4 (Dynesys fixator) and L4-5 (static fixator) by applying the loading conditions of flexion/extension (±7.5 Nm) and lateral bending (±7.5 Nm), with/without a follower preload of 500 N. Our results showed that the hybrid Dynesys-Transition-Optima system can significantly reduce the ROM at the fusion level (L4-L5), whereas the range of motion at the adjacent level (L3-4) significantly increased. The increase in physiological loading could be an important factor in the increment of IDP at the intervertebral discs at the lumbar spine. The Dynesys-Transition-Optima system can preserve the mobility of the stabilized segments with a lesser range of motion on the transition segment; it may help to prevent the occurrence of adjacent segment degeneration. However, the current study cannot cover all the issues of adjacent segmental diseases. Future investigations of large-scale and long-term follow-ups are needed.

Incidence and Characteristics of Clinical L5-S1 Adjacent Segment Degeneration after L5 Floating Lumbar Fusion: A Multicenter Study.

Retrospective study. This study aimed to evaluate the incidence, characteristics, and risk factors for clinical L5-S1 adjacent segment degeneration (ASD) after L5 floating lumbar fusion. ASD is known to occur after lumbar spine fusion at a certain frequency. Several studies on radiological L5- S1 ASD have been reported. However, there are only a few studies on L5-S1 ASD with clinical symptoms, including back pain and/or radiculopathy. In total, 306 patients who received L5 floating lumbar fusion were included in this study. Clinical L5-S1 ASD was defined as newly developed radiculopathy in relation to the L5-S1 segment. Patients' medical records and imaging data were retrospectively analyzed. The risk factors for clinical ASD were assessed by an inverse probability of treatment weighting-adjusted logistic regression analysis. Clinical L5-S1 ASD occurred in 17 patients (5.6%). The mean onset time of L5-S1 ASD was 12.9±7.5 months after the primary surgery. Among these patients, 10 (58.8%) presented with clinical L5-S1 ASD within 12 months. Reoperation was performed in three patients (1.0%). The severity of L5-S1 disk degeneration did not affect the occurrence of L5-S1 ASD. Logistic regression analysis showed that the number of fusion levels was a significant risk factor for clinical L5-S1 ASD. The incidence and characteristics of clinical L5-S1 ASD after L5 floating lumbar fusion were retrospectively investigated. This study established that the number of fusion levels was a significant candidate factor for clinical L5-S1 ASD. Careful clinical follow-up is deemed necessary after L5 floating lumbar fusion surgery, especially for patients who received multiple-level fusions.

Analysis of Risk Factors for Adjacent Segment Degeneration after Minimally Invasive Transforaminal Interbody Fusion at Lumbosacral Spine.

Background Adjacent segment degeneration (ASD) has been considered as a serious complication from changes in the biological stress pattern after spinal fusion. The sagittal balance significantly associated with lumbar loading is largely dependent on L5-S1 segment. However, the evidence indicating risk factors for radiological and symptomatic ASD after minimally invasive transforaminal interbody fusion (MIS-TLIF) remains insufficient. Methods This single-central retrospective study recruited patients with lumbosacral degeneration receiving MIS-TLIF at the L5-S1 level from January 2015 to December 2018. The targeted variables included demographic information, radiological indicators, surgery-related parameters, and patient-reported outcomes (PROs) extracted from the electronic medical system by natural language processing. In these patients, a minimum of 3-year follow-up was done. After reviewing the preoperative and postoperative follow-up digital radiographs, patients were assigned to radiological ASD group (disc height narrowing ≥3 mm, progressive slipping ≥3 mm, angular motion >10°, and osteophyte formation >3 mm), symptomatic ASD group, and control group. We identified potential predictors for radiological and symptomatic ASD with the service of stepwise logistic regression analysis. Results Among the 157 consecutive patients treated with MIS-TLIF in our department, 16 cases (10.2%) were diagnosed with radiological ASD at 3-year follow-up. The clinical evaluation did not reveal suspicious risk factors, but several significant differences were confirmed in radiological indicators. Multivariate logistic regression analysis showed postoperative PI, postoperative DA, and ∆PI-LL in radiological ASD group were significantly different from those in control group. Nevertheless, for patients diagnosed with simultaneously radiological and symptomatic ASD, postoperative DA and postoperative PT as risk factors significantly affected the clinical outcome following MIS-TLIF. Conclusion In this study, while approximately 10% of lumbosacral degenerations develop radiographic ASD, prognosis-related symptomatic ASD was shown not to be a frequent postoperative complication. Postoperative PI, postoperative DA, and mismatched PI-LL are risk factors for radiological ASD, and postoperative DA and postoperative PT are responsible for the occurrence of symptomatic ASD following MIS-TLIF. These radiological risk factors demonstrate that restoration of normal sagittal balance is an effective measure to optimize treatment strategies for secondary ASD prevention.

Biomechanics of extreme lateral interbody fusion with different internal fixation methods: a finite element analysis

BackgroundEstablishing a normal L3–5 model and using finite element analysis to explore the biomechanical characteristics of extreme lateral interbody fusion (XLIF) with different internal fixation methods.MethodThe L3–5 CT image data of a healthy adult male volunteer were selected to establish a normal lumbar finite element model (M0). The range of motion (ROM) of L3–4 and L4–5, under flexion, extension, left bending, right bending, left rotation, and right rotation, together with L3–4 disc pressure was analyzed. Then the L4–5 intervertebral disc was excised and implanted with a cage, supplemented by different types of internal fixation, including lateral two-hole plate model (M1), lateral four-hole plate model (M2), VerteBRIDGE plating model (M3), lateral pedicle model (M4), posterior unilateral pedicle screw model (M5) and posterior bilateral pedicle screw model (M6). The ROM,the maximum stress value of the cage, and the maximum stress value of the intervertebral disc of L3–4 were analyzed and studied .ResultsThe ROM of L3–4 and L4-L5 segments in the validation model under various motion states was basically consistent with previous reports. The lumbar finite element model was validated effectively. After XLIF-assisted internal fixation, the range of activity in L3–4 segments of each internal fixation model was greater than that of the normal model under various working conditions, among which the M5、M6 model had the larger range of activity in flexion and extension. After the internal fixation of L4–5 segments, the mobility in M1-M6 was significantly reduced under various motion patterns. In terms of flexion and extension, the posterior pedicle fixation model (M5、M6) showed a significant reduction,followed by M2. The maximal von mises cage stress of M1 was obviously greater than that of other models (except the left bending). Compared with M0, the intervertebral disc stress of M1-M6 at L3–4 segments was increased.ConclusionsIt is recommended that the posterior bilateral pedicle screw model is the first choice, followed by the lateral four-hole plate model for fixation during XLIF surgery. However, it is still necessary to be aware of the occurrence of adjacent segment degeneration (ASD) in the later stage.

Single-Level Cervical Arthroplasty with a Keel-less Prosthesis: Results in a Series of 35 Patients Operated on for Soft Disk Herniation with a Minimum of 3 Years of Follow-Up.

Cervical arthroplasty with artificial cervical disks has gained popularity as an alternative to anterior discectomy and fusion. The main advantages of disk arthroplasty include maintenance of the range of movement, restitution of disk height and spinal alignment, and reduction of adjacent segment degeneration (ASD). In this article, we aimed to assess the outcomes of the use of a keel-less prosthesis. We included all the patients who underwent single-level cervical arthroplasties with the Discocerv Cervidisc Evolution for "soft" disk herniation. Clinical assessment included Neck Disability Index (NDI) and visual analog scale (VAS) for neck and arm pain. Radiologic studies investigated the occurrence of ASD and system failure or subsidence. The reoperation rate was also recorded. The study included 35 patients (14 men and 21 women; mean age: 42.5 years; mean follow-up: 57.8 months). There was a significant decrease in VAS neck and VAS arm scores, which went from 7.2 and 6.9 preoperatively to 2.2 and 1.7 postoperatively, 2.2 and 1.6 at 6 months, 2.0 and 1.8 at 1 year, and 2.1 and 1.3 at the last follow-up, respectively. The mean NDI score was 58.0 preoperatively, 19.4 postoperatively, 17.0 at 6 months, 16.1 at 1 year, and 16.2 at the last follow-up. Radiologic studies revealed a preserved range of motion in 33 of 35 patients. No ASD occurred and no reoperation was required. Cervical disk arthroplasty with a keel-less prosthesis can be a safe and effective alternative to fusion for degenerative disk disease in selected patients, with a possible reduction of ASD.

Proximal Fusion Level Above First Coronal Reverse Vertebrae: An Essential Factor Decreasing the Risk of Adjacent Segment Degeneration in Degenerative Lumbar Scoliosis.

Retrospective radiological analysis. To explore whether proximal fusion level above first coronal reverse vertebrae (FCRV) could decrease risk of adjacent segment degeneration (ASD) in degenerative lumbar scoliosis (DLS). One hundred and 16 DLS patients were divided into 2 groups according to occurrence of ASD: study group (ASD positive group) and control group (ASD negative group). FCRV was defined as the first vertebrae that presents opposite orientation of asymmetric Hounsfield unit (HU) ratio from the other vertebrae within major curve. Incidence of ASD was evaluated in subgroups according to location between FCRV and upper instrumented vertebrae (UIV). The fusion level was shorter in study group than that in control group. There were 12 patients presented FCRV 2-level proximal than SV, 32 patients presented FCRV 1-level proximal than SV, 35 patients presented the same vertebra of FCRV with SV, 23 patients presented FCRV 1-level distal than SV, 14 patients presented FCRV 2-level distal than SV. When UIV located above FCRV, no patient presented ASD, while 15.4% patients presented ASD when UIV located on FCRV. In study group, proximal scoliosis progression was detected in 1 patient (3.9%) when UIV located on FCRV, and 17 patients (29.8%) when UIV located below FCRV. Proximal fusion level above FCRV could decrease the risk of ASD in DLS, especially for the proximal scoliosis progression. FCRV represent the transitional point of the mechanical load on coronal plane, and may be within a more stable condition than stable vertebrae measured from radiographs.

Changes in cervical range of motion following anterior cervical discectomy with fusion - preliminary results.

The biomechanics of the cervical spine after anterior cervical discectomy with fusion (ACDF), and in particular changes in its global mobility, are phenomena that have not yet been sufficiently studied. Consequently, their effect on the eventual result of treatment is not fully understood. The aim of this study was to assess changes in global and segmental mobility of the cervical spine after ACDF. 28 patients who underwent ACDF for cervical spondylosis were examined. The study was divided into two stages: preoperative and postoperative. Range of motion (ROM) was analysed based on X-ray AP, lateral and functional images: C1-C7, C1-C2, C2-C7, C1-C4, C4-C7, and segments adjacent to the stabilisation. The patients were divided into groups depending on the length of spondylodesis and the occurrence of adjacent segment degeneration (ASDeg). A statistically significant difference was found in the total ROM of C2-C7, C1-C7 and C4-C7 after ACDF. The ROM of C2-C7 decreased by 23%, of C1-C7 by 20%, and of C4-C7 by 38%. These changes occurred by reducing the extension ROM C2-C7 by 33%, C1-C7 by 31%, and C4-C7 by 12%. There was a statistically significant (31%) reduction in total ROM in the segment above ACDF, a 41% reduction in extension ROM of this level in the non-ASDeg group, and a 73% increase in the segmental extension ROM above ACDF in patients with ASDeg. ACDF reduces the total ROM of the cervical spine in the sagittal plane. This change occurs by reducing the neck extension, and its severity depends on the length of the spondylodesis. In patients without ASDeg after ACDF, the mobility of the level above the stabilisation decreases. The occurrence of ASDeg is associated with a higher postoperative ROM of the segment located above the spondylodesis.

Long-term outcomes of Bryan artificial cervical disc replacement for degenerative cervical spondylosis

Objective: To compare the long-term clinical effect and imaging results of Bryan artificial cervical disc replacement (ACDR) and anterior cervical discectomy and fusion (ACDF) and to explore whether ACDR can reduce the occurrence of postoperative adjacent segment degeneration (ASD) in the treatment of degenerative cervical spondylosis. Methods: It was a retrospective study. Total of 60 patients with degenerative cervical spondylosis, who had received operations by Bryan ACDR (n=27) and ACDF (n=33) in the Third Hospital of Hebei Medical University between January 2005 and December 2009 were enrolled in this study. The Japanese Orthopedic Association (JOA) scores, neck disability index (NDI), visual analogue scale (VAS), Odom's scale, cervical range of motion (ROM), surgical segment ROM, heterotopic ossification (HO) and ASD were used to evaluate the clinical and radiologic results. The indices abovementioned were compared between the two groups. Results: The VAS, NDI and JOA scores at each follow-up node in both ACDR and ACDF group were all significantly improved when compared with those before operation (all P<0.05), but there was no significant differences between the two groups (all P>0.05). Of all, 88.9%(24/27) of patients in ACDR group and 84.8%(28/33) of patients in ACDF group achieved excellent or good results, however, there was no significant difference in Odom's scale between the two groups (P>0.05). At the last follow-up, the cervical ROM in ACDR group was 43.2°±8.8°, which was slightly lower than that before operation (45.7°±10.4°), the difference was not statistically significant (t=0.954, P=0.345); the surgical segment ROM in ACDR group was 5.9°±3.6°, which was significantly reduced when compared with that before operation (8.8°±3.4°, t=3.043, P<0.01). However at the last follow-up, the cervical ROM in ACDF group was 36.4°±8.4°, which was significantly reduced when compared with that before operation (43.9°±11.1°), the difference was statistically significant (t=3.095, P<0.01). Although, there was no significant difference in the cervical ROM between the two groups before operation (t=0.643, P=0.523), and the difference was statistically significant at the last follow-up (t=3.054, P<0.01). At the last follow-up, the incidence of HO in ACDR group was 92.6%, and the high-grade HO was 37.0%. The incidence of ASD in ACDR group was 39.5%, which was much lower than that in ACDF group (61.1%, χ(2)=4.462, P=0.035). Conclusion: At minimum follow-up of 10 years, Bryan ACDR achieves a satisfactory clinical effect consistent with ACDF. In terms of advantages, ACDR could maintain the ROM of cervical and retain the ROM of the surgical segment, which reduces the occurrence of ASD by preserving motion.

Optimal Reconstruction of Sagittal Alignment According to Global Alignment And Proportion Score Can Reduce Adjacent Segment Degeneration After Lumbar Fusion.

A retrospective study. The aim of this study was to investigate the ability of Global Alignment and Proportion (GAP) score to predict the occurrence of adjacent segment degeneration (ASD) after fusion surgery for lumbar degenerative diseases. The recently developed GAP score was applied to predict postoperative complications for adult spinal deformity, as well as to facilitate future outcome-based research on optimal treatment for various spinal conditions. However, it remains unclear whether reconstruction of alignment according to GAP score can reduce the ASD rates. This study retrospectively reviewed 126 consecutive patients who had undergone lumbar fusion and had been followed over 2 years. Pre- and postoperative radiographs and MRI were analyzed for ASD. GAP scores were calculated based on the early postoperative spinopelvic parameters. Cochran-Armitage test of trend was performed to investigate the association between GAP score and the occurrence of ASD. Receiver-operating characteristic curves were used to analyze the predictive accuracy of the GAP score for ASD. Radiographical ASD (R-ASD) and symptomatic ASD (S-ASD) were diagnosed in 44 (34.9%) patients and in 13 (10.3%) patients, respectively. The patients with a proportioned spinopelvic state according to the GAP score had significantly lower rates of ASD (R-ASD and S-ASD) or S-ASD than those with a moderately or severely disproportioned spinopelvic state. The area under curve for the GAP score predicting ASD and S-ASD was 0.691 (95% confidence interval [CI]: 0.596∼0.785, P < 0.01) and 0.865 (95% CI: 0.771∼0.958, P < 0.01), respectively. Our study revealed a significant association between postoperative GAP score and occurrence of ASD after lumbar fusion surgery. Setting surgical goals according to the GAP score may help reduce the occurrence of ASD, especially for S-ASD.Level of Evidence: 4.

Efficacy of interspinous device on adjacent segment degeneration after single level posterior lumbar interbody fusion: a minimum 2-year follow-up

Objective Adjacent segment degeneration (ASD) is a well-known problem of posterior lumbar interbody fusion (PLIF). A device for interspinous assisted motion (DIAM) has been recently applied at the adjacent segment to pedicle screw instrumentation to create a dynamic transition zone. The aim of this study was to determine whether DIAM implantation at the adjacent segment could reduce the occurrence of radiologic and symptomatic ASD. Methods This retrospective study reviewed 51 patients who underwent PLIF with or without DIAM between 2005 and 2016. They were followed up for more than 24 months. The mean follow-up was over 5 years. Fourteen patients underwent PLIF with DIAM implantation at the cephalad level (Group A) and 37 patients received PLIF only (Group B). In radiologic ASD, several parameters were measured using pre- and post-operative radiographs and magnetic resonance image for lumbar degenerative disease and paraspinal muscle. Visual analogue scale (VAS) and Roland-Morris Disability Questionnaire (RMDQ) scores of back and leg were used to investigate symptomatic ASD. Results In postoperative radiographic changes, disc height narrowing and progression of spondylolisthesis at adjacent segment were significantly less in group A than those in group B (0.58 mm versus 1.17 mm, p = 0.038 and 0.30 mm versus 1.69 mm, p = 0.041, respectively). In clinical assessments, back VAS and RMDQ scores improved significantly more in group A (−4.07 versus −2.54, p = 0.029 and −7.57 versus −5.43, p = 0.016, respectively). Conclusion DIAM implantation with single-level PLIF could prevent disc height narrowing and progression of spondylolisthesis at adjacent segment. Clinically, DIAM implantation reduced back pain and disability. Therefore, DIAM implantation could help slow the progression of both radiologic and symptomatic ASD.

Biomechanical Analysis of the Cervical Spine Following Disc Degeneration, Disc Fusion, and Disc Replacement: A Finite Element Study.

Discectomy and fusion is considered the "gold standard" treatment for clinical manifestations of degenerative disc disease in the cervical spine. However, clinical and biomechanical studies suggest that fusion may lead to adjacent-segment disease. Cervical disc arthroplasty preserves the motion at the operated level and may potentially decrease the occurrence of adjacent segment degeneration. The purpose of this study was to investigate the effect of disc generation, fusion, and disc replacement on the motion, disc stresses, and facet forces on the cervical spine by using the finite element method. A validated, intact, 3-dimensional finite element model of the cervical spine (C2-T1) was modified to simulate single-level (C5-C6) and 2-level (C5-C7) degeneration. The single-level degenerative model was modified to simulate both single-level fusion and arthroplasty (total disc replacement [TDR]) using the Bryan and Prestige LP discs. The 2-level degenerative model was modified to simulate a 2-level fusion, 2-level arthroplasty, and single-level disc replacement adjacent to single-level fusion (hybrid). The intact models were loaded by applying a moment of ±2 Nm in flexion-extension, lateral bending, and axial rotation. The motion in each direction was noted and the other modified models were loaded by increasing the moment until the primary C2-T1 motion matched that of the intact (healthy) C2-T1 motion. Both Bryan and Prestige discs preserved motion at the implanted level and maintained normal motions at the adjacent nonoperative levels. A fusion resulted in a decrease in motion at the fused level and an increase in motion at the unfused levels. In the hybrid construct, the TDR (both) preserved motion adjacent to the fusion, thus reducing the demand on the other levels. The disc stresses followed the same trends as motion. Facet forces increased considerably at the index level following a TDR. The Bryan and Prestige LP TDRs both preserved motion at the implanted level and maintained normal motion and disc stresses at the adjacent levels. The motion patterns of the spine with a TDR more closely resembled that of the intact spine than those of the degenerative or fused models.