Clinical management of bone loss in cervical total disc arthroplasty: literature review and treatment recommendations.

PURPOSE: Cervical total disc replacement (cTDR) has been established as an alternative treatment for degenerative cervical radiculopathy and myelopathy. While the rate of complications for cTDR is reasonably low, recent studies have focused on bone loss after cTDR. The purpose of this work is to develop a clinical management plan for cTDR patients with evidence of bone loss. To guide our recommendations, we undertook a review of the literature and aimed to determine: (1) how bone loss was identified/imaged, (2) whether pre- or intraoperative assessments of infection or histology were performed, and (3) what decision-making and revision strategies were employed. METHODS: We performed a search of the literature according to PRISMA guidelines. Included studies reported the clinical performance of cTDR and identified instances of cervical bone loss. RESULTS: Eleven case studies and 20 cohort studies were reviewed, representing 2073 patients with 821 reported cases of bone loss. Bone loss was typically identified on radiographs during routine follow-up or by computed tomography (CT) for patients presenting with symptoms. Assessments of infection as well as histological and/or explant assessment were sporadically reported. Across all reviewed studies, multiple mechanisms of bone loss were suspected, and severity and progression varied greatly. Many patients were reportedly asymptomatic, but others experienced symptoms like progressive pain and paresthesia. CONCLUSION: Our findings demonstrate a critical gap in the literature regarding the optimal management of patients with bone loss following cTDR, and treatment recommendations based on our review are impractical given the limited amount and quality evidence available. However, based on the authors' extensive clinical experience, close follow-up of specific radiographic observations and serial radiographs to assess the progression/severity of bone loss and implant changes are recommended. CT findings can be used for clinical decision-making and further follow-up care. The pattern and rate of progression of bone loss, in concert with patient symptomatology, should determine whether non-operative or surgical intervention is indicated. Future studies involving implant retrieval, histopathological, and microbiological analysis for patients undergoing cTDR revision for bone loss are needed.

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

PURPOSE: 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. METHOD: 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 1 week, 6 months, 1 year, 2 years, 5 years, 10 years 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). RESULTS: 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 6 m and especially between 6 m 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. CONCLUSIONS: 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.

Artificial intelligence in predicting postoperative heterotopic ossification following anterior cervical disc replacement.

OBJECTIVE: This study aimed to develop and validate a machine learning (ML) model to predict high-grade heterotopic ossification (HO) following Anterior cervical disc replacement (ACDR). METHODS: Retrospective review of prospectively collected data of patients undergoing ACDR or hybrid surgery (HS) at a quaternary referral medical center was performed. Patients diagnosed as C3-7 single- or multi-level cervical disc degeneration disease with > 2 years of follow-up and complete pre- and postoperative radiological imaging were included. An ML-based algorithm was developed to predict high grade HO based on perioperative demographic, clinical, and radiographic parameters. Furthermore, model performance was evaluated according to discrimination and overall performance. RESULTS: In total, 339 ACDR segments were included (61.65% female, mean age 45.65 ± 8.03 years). Over 45.65 ± 8.03 months of follow-up, 48 (14.16%) segments developed high grade HO. The model demonstrated good discrimination and overall performance according to precision (High grade HO: 0.71 ± 0.01, none-low grade HO: 0.85 ± 0.02), recall (High grade HO: 0.68 ± 0.03, none-low grade HO: 0.87 ± 0.01), F1-score (High grade HO: 0.69 ± 0.02, none-low grade HO: 0.86 ± 0.01), and AUC (0.78 ± 0.08), with lower prosthesis­endplate depth ratio, higher height change, male, and lower postoperative-shell ROM identified as the most important predictive features. CONCLUSION: Through an ML approach, the model identified risk factors and predicted development of high grade HO following ACDR with good discrimination and overall performance. By addressing the shortcomings of traditional statistics and adopting a new logical approach, ML techniques can support discovery, clinical decision-making, and intraoperative techniques better.

Heterotopic ossification, osteolysis and implant failure following cervical total disc replacement with the M6-C™ artificial disc.

INTRODUCTION: A recent study reported a 34% mid-term revision rate after M6-C™ cervical total disc replacement (CTDR) for wear-related osteolysis. Here, we aim to investigate the prevalence, risk factors, and radiographic characteristics of periprosthetic bony changes and implant failure of the M6-C™ artificial disc. METHODS: We retrospectively analysed radiographic (conventional X-ray, CT scan) and clinical outcomes (EQ-5D-5L, Neck Disability Index (NDI), and Visual Analog Scale (VAS) for neck and arm pain) data collected during routine follow-up of patients who underwent CTDR with the M6-C™ between 2011 and 2015. RESULTS: In total, 85 patients underwent CTDR with the M6-C™. Follow-up data were available for 43 patients (54% female, mean age 44 years) with 50 implants and a mean follow-up of 8.1 years (6.5-11 years). Implant failure with the presence of severe osteolysis was identified in 5 (12%) patients who were all male (p = 0.016) and implanted at the C5/6 level (p = 0.11). All failed implants required revision surgery. The overall prevalence of osteolysis was 44% (22/50 implants) and 34% (17/50 implants) for significant heterotopic ossification. Patients with high-grade osteolysis showed higher VAS arm pain (p = 0.05) and lower EQ-5D-VAS health VAS (p = 0.03). CONCLUSION: We report a lower reoperation rate for failed M6-C™ implants than previously published, but confirmed that osteolysis and heterotopic ossification are common following CTDR with the M6-C™ and may be asymptomatic. Therefore, we strongly recommend ongoing clinical and radiographic monitoring after CTDR with the M6-C™, particularly for male patients implanted at the C5/6 level.

Risk factors of bone loss after Prestige-LP cervical disc arthroplasty.

PURPOSE: Cervical disc arthroplasty (CDA) is widely employed for patients diagnosed with cervical degenerative disc disease (CDDD). Postoperative bone loss (BL) represents a radiological alteration that is a relatively novel consideration in the realm of CDA. This study endeavors to examine the risk factors associated with BL following CDA, aiming to elucidate the underlying mechanisms and the impact of BL on surgical outcomes. METHODS: A retrospective study was undertaken, encompassing consecutive patients subjected to one-level CDA, two-level CDA, or two-level hybrid surgery (HS) for the treatment of CDDD at our institution. Patient demographic and perioperative data were systematically recorded. Radiological images obtained preoperatively, at 1-week post-operation, and during the last follow-up were collected and evaluated, following with statistical analyses. RESULTS: A total of 295 patients and 351 arthroplasty segments were involved in this study. Univariate logistic regressions indicated that age ≥ 45 years and two-level HS was associated with lower risk of BL; and a greater ΔDA (change of disc angle before and after surgery) was correlated with an increased risk of BL. Multivariate logistic regression determined that two-level HS and greater ΔDA were independent preventative and risk factors for BL, respectively. Further analysis revealed that severe BL significantly elevated the risk of implant subsidence compared to non-BL and mild BL. CONCLUSIONS: This study posited bone remodeling and micromotion as potential underlying mechanisms of BL. Subsequent research endeavors should delve into the divergent mechanisms and progression observed between lower- and higher-grade BL, aiming to prevent potential adverse outcomes associated with severe BL.

Influence of the deviated center of rotation on facet joint degeneration after cervical disc replacement - an in vivo study with a minimum of 10-year follow-up.

BACKGROUND: Short term results of the change of center of rotation (COR) after Bryan cervical disc replacement (CDR) have been reported. However, there is a lack of long-term studies focusing on the COR and its influences on facet joint degeneration. OBJECTIVE: To evaluate the long-term clinical and radiographic results of Bryan CDR, and to explore the influence of deviated COR on facet joint degeneration at index level. METHODS: It is a retrospective follow up study conducted in China. Eighty-three consecutive patients who received single-level Bryan CDR were retrospectively reviewed. Clinical evaluation included Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and Odom's scale. Radiographic evaluation underwent before surgery, at early follow-up (3 months) and last follow-up (10 years). The radiographic parameters included range of motion (ROM), location of COR presented by the coordinates (COR-x, COR-y), and facet joint degeneration score. Correlation analysis was conducted between changes of COR and facet joint degeneration score. RESULTS: Fifty-nine patients were included, with an average age of 44.6 ± 7.4 years. The mean follow-up time was 135.7 ± 12.4 (120-155) months. JOA score, NDI and Odom's scale showed significant improvements at last follow-up. The ROM was well preserved through follow-up. 33 patients (55.9%) showed deterioration of facet joint degeneration at index level. The increment of facet joint degeneration score at index level was strongly correlated with the change of COR-x (r = 0.758, P < 0.001), and weakly correlated with the change of COR-y (r=-0.473, P < 0.001). The deviation of COR was significantly greater in Group Degeneration than that in Group Non-degeneration (14.8 ± 10.5% vs. -2.6 ± 8.1% for COR-x, and - 6.4 ± 7.5% vs. 0.8 ± 8.3% for COR-y). CONCLUSIONS: Bryan CDR with minimum of 10-year follow-up achieved favorable clinical outcome and good maintenance of ROM. Deviated COR could be an important risk factor for facet joint degeneration.

Trends in use, outcomes, and revision procedures of anterior cervical disc replacement in the United States: a premiere database analysis from 2006-2019.

PURPOSE: We sought to characterize trends in demographics, comorbidities, and postoperative complications among patients undergoing primary and revision cervical disc replacement (pCDR/rCDR) procedures. METHODS: In this retrospective database study, the Premier Healthcare database was queried from 2006 to 2019. Annual proportions or medians were calculated for patient and hospital characteristics, comorbidities, and postoperative complications associated with CDR surgery. Trends were assessed using linear regression analyses with year of service as the sole predictor. RESULTS: A total of 16,178 pCDR and 758 rCDR cases were identified, with a median (IQR) age of 46 (39; 53) and 51 (43; 60) years among patients, respectively. The annual number of both procedures increased between 2006 and 2019, from 135 to 2220 for pCDR (p < 0.001), and from 17 to 49 for rCDR procedures (p < 0.001), with radiculopathy being the main indication for surgery in both groups. Mechanical failure was identified as a major indication for rCDR procedures with an increase over time (p = 0.002). Baseline patient comorbidity burden (p = 0.045) and complication rates (p < 0.001) showed an increase. For both procedures, an increase in outpatient surgeries and procedures performed in rural hospitals was seen (pCDR: p = 0.045; p = 0.006; rCDR: p = 0.028; p = 0.034). CONCLUSION: PCDR and rCDR procedures significantly increased from 2006 to 2019. At the same time, comorbidity burden and complication rates increased, while procedures were more often performed in an outpatient and rural setting. The identification of these trends can help guide future practice and lead to further areas of research.

Cervical disc arthroplasty with the Baguera C prosthesis: clinical and radiological results of a 10-year follow-up study.

PURPOSE: We evaluated the long-term safety, mobility and complications of cervical total disc arthroplasty with the Baguera®C prosthesis over 10 years. METHODS: We included 91 patients treated by arthroplasty for cervical degenerative disc disease. A total of 113 prostheses were implanted (50 one-level, 44 two-level and 19 hybrid constructs). They were assessed for complications, clinically, with NDI and SF-12 questionnaires and by independent radiologists for ROM, HO, disc height and adjacent level degeneration. RESULTS: No spontaneous migration, loss of fixation, subsidence, vascular complication or dislocation were observed. The reoperation rate was 1%. About 82.7% of the patients were pain free. About 9.9% were taking occasional grade I painkillers. Motricity and sensitivity were preserved in 98.8% and 96.3%. The NDI showed an average functional disability of 17.58%, 26% lower than preoperatively. The SF-12 scores were close to normal health. The average ROM at the treated level was 7.4°. Motion was preserved in 86.6%. Lack of motion was observed in 13.4%. Grades II and III H0 were present in 53.7% and 31.7%, respectively, Grade IV was present in 13.4%. Motion was preserved in 100% of the grades 0-III. The preoperative adjacent level disc height of 4.3 mm remained stable during all the follow-ups at 4.4 mm and 4.2 mm, respectively, at 5 and 10 years. CONCLUSIONS: After 10 years, cervical arthroplasty with the Baguera®C prosthesis presents excellent safety and functional results and low complications. Motion was preserved in 86.6%, with a 7.4° ROM. Although common, HO did not hinder motion. Adjacent disc height preservation confirms some adjacent level degeneration protection.

Midterm osteolysis-induced aseptic failure of the M6-C™ cervical total disc replacement secondary to polyethylene wear debris.

BACKGROUND: According to published meta-analyses, cervical total disc replacement (CTDR) seems to be superior to anterior cervical decompression and fusion (ACDF) in most clinical parameters. Despite short-term clinical success of CTDR, there are concerns regarding long-term durability of these prostheses. METHODS: This prospective study involved 382 patients who received standalone CTDR or a hybrid procedure (ACDF/CTDR). A retrospective comparison between different CTDR devices was conducted regarding patient-reported outcome measures (PROMs), failure scenarios, and revision surgeries. The M6-C™ Artificial Cervical Disc (Orthofix, Lewisville, Texas) cohort was compared to the other CTDR devices clinically. Etiological reasons for revision, and the surgical technique of the revision was investigated. RESULTS: Fifty-three patients received M6-C CTDR. Eighteen patients (34%) were revised at an average of 67 months postoperatively for wear-induced osteolysis. There were three additional cases of pending revision. The PROMs of the two groups were similar, indicating that the failure mode (wear-induced osteolysis) is often asymptomatic. The demographics of the two groups were also similar, with more women undergoing revision surgery than men. There were three one-level CTDR, four two-level hybrids, seven three-level hybrids, and three four-level hybrids revised anteriorly. Sixteen patients underwent removal of the prosthesis and were treated according to the extent of osteolysis. There were four vertebrectomies, six revisions to ACDF, and six revisions to another CTDR. One patient underwent supplemental fixation using a posterior approach. The other CTDR cohort had an incidence of 3.3% at the equivalent time, and none of these were due to osteolysis or wear-related events. CONCLUSIONS: There is a concerning midterm failure rate related to ultra-high-molecular-weight-polyethylene wear-induced osteolysis in the M6-C. Patients implanted with the M6-C prosthesis should be contacted, informed, and clinically and radiologically assessed.

Impact of heterotopic ossification following lumbar total disk replacement: a systematic review.

BACKGROUND CONTEXT: Lumbar total disc replacement (TDR) is an alternative to lumbar fusion in the treatment of lower back pain and reduces the risk of adjacent segment degeneration. Heterotopic ossification (HO) has been identified as a common complication following lumbar TDR. PURPOSE: This systematic review aims to determine the prevalence, risk factors and clinical and radiological impact of HO following lumbar TDR. STUDY DESIGN: Systematic Review. METHODS: MEDLINE, Scopus, PubMed and Cochrane Central were searched for articles that referred to lumbar TDR and HO. The hits were assessed against inclusion and exclusion criteria. Data from each included study was extracted and analysed with respect to the study aims. RESULTS: Twenty-six studies were included in this review and the pooled prevalence of HO was estimated to be between 13.2% (participants) and 15.3% (vertebral levels). TDR clinical outcomes were not found to be reduced by HO and there was insufficient data to identify a given impact upon radiological outcomes. Age and follow up time were identified as potential risk factors for HO. CONCLUSIONS: This review was hampered by inconsistencies in the reporting of HO across the studies. We therefore recommend that a set of guidelines should be produced to aid future researchers and reduce the risk of bias.

Spinal cord compression due to nucleus migration from Mobi-C total disc replacement.

Cervical disc replacement is an alternative option to an anterior cervical discectomy and fusion for cervical spine degenerative disease. We present the first reported case of a progressively worsening symptomatic spinal cord compression secondary to migration of the nucleus from a Mobi-C total disc replacement.

A meta-analysis comparing the short- and mid- to long-term outcomes of artificial cervical disc replacement(ACDR) with anterior cervical discectomy and fusion (ACDF) for the treatment of cervical degenerative disc disease.

PURPOSE: Anterior cervical discectomy and fusion (ACDF) surgery is commonly performed to treat cervical degenerative disc disease (CDDD). The lost of range of motion (ROM) is also found after ACDF, which contributes to degenerate in adjacent segment disease (ASD). Artificial cervical disc replacement (ACDR), an alternative to ACDF, is developed to preserve the ROM and reduce ASD. This article aims to compare the outcomes between ACDR and ACDF in the short-, mid-, and long-term. METHODS: Databases including Cochrane, Embase, PubMed, and Web of Science were searched. Only RCTs were included in this meta-analysis, and the search strategy followed the requirements of the Cochrane Handbook. The strength of evidence was assessed using GRADE. Two reviewers independently assessed the methodological quality of each included study and extracted the relevant data. RESULTS: Thirty prospective RCTs were included. Prolonged operative duration, better overall success, neurological success, and NDI success rates were found in ACDR group in all follow-up periods, with lower dysphagia/dysphonia during short-term follow-up. Moreover, a lower ASD was found in ACDR group during long-term follow-up and overall analysis, with lower reoperation rates in all follow-up periods. Comparable length of hospital stay and blood loss were found in both groups. Moreover, ASD was similar in short- and mid-term follow-ups, while dysphagia/dysphonia incidence was similar in mid- and long-term follow-ups. The incidence of implant events was comparable in all follow-up periods (p > 0.05). CONCLUSIONS: ACDR is as effective as ACDF and superior for some success rates. Disc replacement can reduce the risk of dysphagia/dysphonia, ASD, and re-operation.

Heterotopic Ossification After Prestige-LP Cervical Disc Arthroplasty Is Related to Insufficient Sagittal Coverage of the Endplate By the Prosthesis.

BACKGROUND Heterotopic ossification (HO) is a major complication after cervical disc arthroplasty (CDR) that has attracted the attention of spine surgeons. There remains a great deal of controversy regarding the surgical risk factors. The present study investigated the correlation between insufficient sagittal coverage of the prosthesis-endplate and HO after CDR and explored strategies to prevent it. MATERIAL AND METHODS We included 73 patients who underwent Prestige-LP arthroplasty. Patients were divided into HO and non-HO groups. Related data, including radiological, clinical information, were collected. HO was graded using the McAfee classification. Analysis was performed to correlate HO to the surgical segmental range of motion (ROM) at last follow-up. To evaluate the insufficient sagittal coverage of the prosthesis-endplate and other factors for developing HO, receiver operating characteristic (ROC) curves were analyzed for insufficient sagittal coverage. RESULTS Among 73 patients, 24 patients had HO at the last follow-up (HO incidence: 32.9%). The ROM in the HO group was significantly lower (P<0.001). The insufficient sagittal coverage of the upper and lower prosthesis-endplate, the height of intervertebral space, and the preoperative and postoperative ROM were related to HO (P<0.05). Multivariate logistic regression analysis showed that only insufficient sagittal coverage of the upper prosthesis-endplate was related to HO (P=0.023), and ROC curve analysis revealed that HO was more likely to occur with insufficient sagittal coverage distance ≥2.5 mm. CONCLUSIONS HO after CDR causes a reduction in ROM, the occurrence of which is associated with insufficient sagittal coverage of the prosthesis-endplate. HO was more likely to occur with insufficient sagittal coverage distance ≥2.5 mm.

Management of Vascular Complications during Anterior Lumbar Spinal Surgery Using Mini-Open Retroperitoneal Approach.

BACKGROUND: Anterior retroperitoneal spine exposure has become increasingly performed for the surgical treatment of various spinal disorders. Despite its advantages, the procedure is not riskless and can expose to potentially life-threatening vascular lesions. The aim of this review is to report the vascular lesions that can happen during anterior lumbar spinal surgery using mini-open retroperitoneal approach and to describe their management. METHODS: A systematic literature search was performed according to PRISMA to identify studies published in English between January 1980 and December 2019 reporting vascular complications during anterior lumbar spinal surgery with mini-open retroperitoneal approach. Three authors independently conducted the literature search on PubMed/Medline database using a combination of the following terms: "spinal surgery", "anterior lumbar surgery (ALS)", "anterior lumbar interbody fusion (ALIF)", "lumbar total disc replacement", "artificial disc replacement", "vascular complications", "vascular injuries". Vascular complications were defined as any peri-operative or post-operative lesions related to an arterial or venous vessel. The management of the vascular injury was extracted. RESULTS: Fifteen studies fulfilled the inclusion criteria. Venous injuries were observed in 13 studies. Lacerations and deep venous thrombosis ranged from 0.8% to 4.3% of cases. Arterial lesions were observed in 4 studies and ranged from 0.4% to 4.3% of cases. It included arterial thrombosis, lacerations or vasospasms. The estimated blood loss was reported in 10 studies and ranged from 50 mL up to 3000 mL. Vascular complications were identified as a cause of abortion of the procedure in 2 studies, representing respectively 0.3% of patients who underwent ALS and 0.5% of patients who underwent ALIF. CONCLUSION: Imaging pre-operative planning is of utmost importance to evaluate risk factors and the presence of anatomic variations in order to prevent and limit vascular complications. Cautions should be taken during the intervention when manipulating major vessels and routine monitoring of the limb oxygen saturation should be systematically performed for an early detection of arterial thrombosis. The training of the surgeon access remains a key-point to prevent and manage vascular complications during anterior lumbar spinal surgery with mini-open retroperitoneal.

Advanced meta-analyses comparing the three surgical techniques total disc replacement, anterior stand-alone fusion and circumferential fusion regarding pain, function and complications up to 3 years to treat lumbar degenerative disc disease.

PURPOSE: The purpose of our meta-analyses is to find the most appropriate surgical technique treating lumbar degenerative disc disease (DDD). Spinal fusion is the conventional treatment for lumbar DDD. Total disc replacement (TDR) has been developed to avoid negative effects of fusions by preserving functionality. To our knowledge, there is no evaluation comparing meta-analytically the clinical results of three different surgical techniques with same inclusion and exclusion criteria for treating DDD. METHODS: The surgical techniques TDR, anterior lumbar interbody fusion (ALIF) and circumferential fusion (CFF) are pairwise meta-analytically compared. Primary outcomes are pain measured by the Visual Analogue Scale (VAS) and function measured by the Oswestry Disability Index (ODI). Secondary outcomes are the mean number of complications per case (MNOC) at surgery and follow-up and the overall MNOC. RESULTS: In our systematic search, we found finally six prospective studies with the minimum follow-up of two years: four randomized controlled trials and two cohort studies. In VAS and ODI, TDR is proved to be superior to ALIF and CCF (p < 0.05), whereat ALIF is more effective than CFF without statistical significance. CFF presents the best result in complications with the lowest overall MNOC (0.1), followed by TDR (1.2) and ALIF (1.5). CONCLUSION: According to our meta-analyses, we regard TDR to be the most appropriate surgical technique treating DDD, followed by ALIF. Further studies with a longer follow-up are needed using the same methodical approach to strengthen the VAS and ODI results and to explain the discrepant result to complications.

Unintended fusion in cervical artificial disk replacement: a prospective study on heterotopic ossification, progression, and clinical outcome, with 5-year follow-up.

PURPOSE: Heterotopic ossification (HO) may cause unintended fusion in artificial disk replacement (ADR), failing to preserve motion. The reported incidence of HO varies hugely. This study aimed to determine prevalence of HO, progression, predisposing factors to occurrence and to progression, and potential effect on clinical outcomes. METHODS: Eighty-three patients treated with ADRs for cervical radiculopathy at one or two segments were extracted from a previously published RCT. Of the 83 patients, 59 had remaining ADR (79 implants) and sufficiently high-quality X-rays at 5 years of follow-up to allow analysis. HO was graded on plain films according to Mehren/Suchomel. Prevalence, progression, predisposing factors and effect on clinical outcome (Neck Disability Index-NDI) were analyzed. RESULTS: At 2 years, HO was seen in 46/55 ADR implants (84%), severe enough to affect mobility in 27/55 (49%). At 5 years, HO was seen in 92% of 79 implants, severe in 71%. Male sex was a predisposing factor to HO. No predisposing factors to progression were identified. NDI was not affected by the severity of HO. CONCLUSION: Almost all ADR implants in our study have HO at 5 years of follow-up. Male sex is a risk factor. Severe HO did not affect clinical outcome. TRIAL REGISTRATION: Study registered at ISRCTN (registration number: 44347115).

Pretic-I was a safe and effective artificial cervical disc prosthesis--a retrospective and comparative study with 5-year follow-up.

BACKGROUND: The newly designed cervical disc prosthesis, Pretic-I, had been finished its limited clinical use for over 5 years. At a short-term follow-up of 2 years, we obtained satisfactory clinical results. The long-term clinical efficacy and safety of Pretic-I will now be analyzed. METHODS: Peri-operative parameters included intra-operative blood loss, operation time, off-bed time. Clinical parameters included visual analogue scale (VAS) for arm and neck, neck disability index (NDI), and Japanese Orthopaedic Association (JOA) score. Radiological parameters included C2-7 Cobb angle, Shell angle, and the range of motion (ROM) of C2-7, functional segment unit (FSU), and adjacent FSU. The CDA-related complications included adjacent segment degeneration (ASDeg), adjacent segment disease (ASDis), heterotopic ossification (HO), prosthesis subsidence, prosthesis displacement, and dysphagia. RESULTS: A total 64 patients from two independent centers received a single-level CDA with Discover (n = 32) and Pretic-I (n = 32), and all of patients finished a 5-year follow-up. There're no significant differences between two groups in peri-operative parameters. The clinical parameters improved greatly in Pretic-I group (p<0.0001), and there's no statistical difference from Discover group. Furthermore, Pretic-I could slightly improve the cervical curvature (15.08 ± 11.75 to 18.00 ± 10.61, p = 0.3079) and perfectly maintain the Shell angle (3.03 ± 3.68 to 2.23 ± 4.10, p = 0.1988), cervical ROM (52.48 ± 14.31 to 53.30 ± 11.71, p = 0.8062) and FSU ROM (12.20 ± 4.52 to 10.73 ± 4.45, p = 0.2002). The incidence of high-grade HO (Grade III-IV) at the final follow-up was significantly lower in Pretic-I group than in Discover group (12.50% vs. 34.38%, p = 0.0389, Statistical Power = 95.36%). The incidences of other CDA-related complications in Pretic-I group were also well-accepted, comparable to the Discover group, without significant differences. CONCLUSION: CDA with Pretic-I demonstrated a well-accepted and sustained clinical outcome, with a significantly lower incidence of high-grade HO. This newly designed prosthesis is expected to become an alternative choice for cervical disc prosthesis in the future.

[Quantitative analysis of the degeneration of cervical spine and the correlation to the heterotopic ossification after artificial cervical disc replacement].

Objective: To investigate parameters related to quantifying the amount of degeneration in preoperative patients to identify ideal indication of artificial cervical disc replacement (ACDR) in patient with a minimum of 10 years of follow-up data. Methods: From January 2004 to August 2008, a total of 44 patients underwent single level Bryan cervical disk replacement performed by the same group of surgeons were involved in this retrospective study, and all of the patients in this group had at least 10 years of follow-up data. Heterotopic ossification (HO) was graded in radiographic images by using the McAfee classification. Preoperative degeneration of cervical spine was evaluated in radiographs based on a quantitative"9 points"scoring system. Univariate analysis and multifactor logistic regression were made to identify significant factors. To determine the cut-off points for the significant factors, a receiver operating characteristic (ROC) curve analysis was conducted. Results: The incidence of HO in study group was 61.4%. Based on univariate analysis results, there were significant differences in the scores of disc height, the presence of anterior osteophytes and endplate sclerosis between the HO group and non-HO group (all P<0.05), and the indices were included in the multivariate analysis. According to the logistic regression results, disc height and endplate sclerosis were identified as the independent risk factors for HO(OR(95%CI): 10.801(1.202-97.064), 37.870(1.581-907.237), respectively, both P<0.05). ROC analysis showed the area under the curve (AUC) of disc height and endplate sclerosis were 0.822 and 0.792, respectively. According to the scoring system, the ROC curve indicated that both the optimal cutoff points were 1.5. Conclusion: The incidence of postoperative HO is relatively high among the patients who had more than 10 years follow-up, and the amount of degeneration in the target level before surgery correlated with the incidence of HO.

Predictors and Outcomes of Paramedian Incisional Hernia After Anterior Spine Exposure.

BACKGROUND: Anterior exposures for lumbar spine surgery are increasingly common for treating various spinal pathologies. A retroperitoneal approach via a paramedian incision has grown rapidly in popularity, but little is known about the risk of incisional hernia development with this technique. We sought to assess the incidence of paramedian incisional hernia development and identify risk factors that are associated with occurrence. MATERIALS AND METHODS: We conducted a retrospective review of all patients who underwent anterior lumbar spine exposure by a paramedian approach between 2012 and 2017 at a single, tertiary medical center. The primary outcome was the development of postoperative paramedian incisional hernia. RESULTS: Of the 735 patients included in the study, 445 (60.5%) were women, and the mean (standard deviation) age of all patients was 60 y (12.4). Nearly all (97.4%) paramedian approaches were performed with a vascular surgeon present. Median follow-up time was 10 mo (interquartile range 3.5-19.9). Postoperative paramedian hernia developed in 20 patients (2.7%), of which 14 underwent repair. The mean (standard deviation) size of the hernia was 13.5 cm (5.5); 9 of 14 (64%) were repaired with synthetic mesh, whereas 3 of 14 (21%) required bowel resection. On multivariate analysis, risk factors associated with hernia development were male gender (0.045), higher American Society of Anesthesiologists class (0.039), history of abdominal surgery (P = 0.013), and postoperative intensive care unit admission (P = 0.02). CONCLUSIONS: A paramedian approach for anterior lumbar spine exposure resulted in a low rate of incisional hernia with minimal morbidity. Surgeons involved in these collaborative procedures should consider the risk factors that predispose patients to develop these hernias.

Complications of cervical total disc replacement and their associations with heterotopic ossification: a systematic review and meta-analysis.

PURPOSE: Although cervical total disc replacement (CTDR) is perceived as a safe procedure, no review to date has quantified the complication rates. Of note, heterotopic ossification (HO), one of the complications of CTDR, is hypothesised to cause adjacent segment degeneration (ASDegeneration). This association has not been proven in meta-analysis. Hence, this systematic review and meta-analysis aims to investigate the pooled prevalence of complications following CTDR among studies that concomitantly reported the rate of HO, and the associations between HO and other complications, including ASDegeneration. METHODS: Literatures search was conducted in Embase, MEDLINE, PubMed, and the Cochrane Central Register of Controlled Trials. Complications were stratified into ≥ 1 and < 2 years, ≥ 2 and < 5 years, and ≥ 5 years follow-up. Subgroup and meta-regression analyses were performed. RESULTS: Fifty-three studies were included, composed of 3223 patients in total. The pooled prevalence of post-operative complications following CTDR was low, ranging from 0.8% in vascular adverse events to 4.7% in dysphagia at short-term follow-up. The rate of ASDegeneration was significantly higher at long-term follow-up (pooled prevalence 36.0%, 95% confidence interval [CI] 22.8-49.1%) than that at mid-term follow-up (pooled prevalence 7.3%, 95% CI 2.8-11.8%). Multivariate meta-regression analysis demonstrated that ASDegeneration was independently and inversely correlated with age (p = 0.007) and positively correlated with HO (p = 0.010) at mid-term follow-up. At long-term follow-up, ASDegeneration was still positively correlated with HO (p = 0.011), but not age. Furthermore, dysphagia was inversely associated with HO (p = 0.016), after adjustment for age and length of follow-up. CONCLUSION: In conclusion, HO is associated with ASDegeneration and dysphagia.