Early Subsidence Research Articles

Risk factors for early subsidence of 3D Printed Artificial vertebral after anterior cervical corpectomy and fusion

ObjectiveThe subsidence of vertebral body replacement may occur after anterior cervical corpectomy and fusion (ACCF) , which may lead to cervical kyphosis, spinal cord compression and neurological dysfunction. The authors aim to investigate the risk factors for early subsidence of 3D printed artificial vertebral (3D-PAVB) after ACCF surgery and to provide guidance for clinical practice. MethodsA retrospective analysis was conducted on the data of consecutive patients with cervical spondylosis who underwent ACCF surgery at Bethune Hospital of Shanxi from 2017 to 2020. The statistical data included age, gender, disease type, body mass index (BMI), surgical segment, vertebral height, Cobb Angle, and Hounsfeld Units (HU) values of the vertebral body and endplate. The clinical efficacy of the surgery was evaluated using Visual Analog Scale (VAS), Japanese Orthopedic Association (JOA), and Neck Disability Index (NDI). Follow-up data, such as VAS, JOA, NDI, and Cobb Angle, were obtained using a repeated-measures ANOVA analysis. Univariate analysis was conducted to identify the factors contributing to the early subsidence of the3D-PAVB, and independent risk factors were determined using logistic regression. The HU value was analyzed using the Receiver Operating Characteristic (ROC) curve and the area under the Area Under Curve (AUC) to predict the subsidence of the 3D-PAVB. ResultsA total of 66 patients were included in the study, out of which 19 patients experienced subsidence of 3D-PAVB,resulting in an incidence rate of 28.8%. The postoperative JOA, VAS, and NDI scores showed significant improvement in both the subsidence and non-subsidence groups. Upon conducting univariate analysis, significant differences were observed between the two groups in terms of age, diabetes, smoking, and lower vertebral Computed Tomography (CT) values. The average HU value of the subsidence group (251.39±52.615, n=19) was significantly lower than that of the non-subsidence group (317.06±73.587, n=47, p＜0.01). Multivariate analysis revealed that smoking and HU of the lower vertebra were independent risk factors for 3D-PAVB subsidence, with an AUC of 0.772 and an optimal threshold of 272 for HU (sensitivity 78.9%, specificity 74.5%). ConclusionThe occurrence of early subsidence of 3D-PAVB post ACCF surgery is influenced by two independent risk factors - smoking and low HU. To predict the likelihood of this outcome, it is advisable to consider smoking history and measure CT HU value prior to surgery. A lower CT HU value is indicative of a greater risk of subsidence.

Two stages of subsidence and its formation mechanisms in Mid-Late Triassic Ordos Basin, NW China

Based on a large number of newly added deep well data in recent years, the subsidence of the Ordos Basin in the Mid-Late Triassic is systematically studied, and it is proposed that the Ordos Basin experienced two important subsidence events during this depositional period. Through contrastive analysis of the two stages of tectonic subsidence, including stratigraphic characteristics, lithology combination, location of catchment area and sedimentary evolution, it is proposed that both of them are responses to the Indosinian Qinling tectonic activity on the edge of the craton basin. The early subsidence occurred in the Chang 10 Member was featured by high amplitude, large debris supply and fast deposition rate, with coarse debris filling and rapid subsidence accompanied by rapid accumulation, resulting in strata thickness increasing from northeast to southwest in wedge-shape. The subsidence center was located in Huanxian–Zhenyuan–Qingyang–Zhengning areas of southwestern basin with the strata thickness of 800–1 300 m. The subsidence center deviating from the depocenter developed multiple catchment areas, until then, unified lake basin has not been formed yet. Under the combined action of subsidence and Carnian heavy rainfall event during the deposition period of Chang 7 Member, a large deep-water depression was formed with slow deposition rate, and the subsidence center coincided with the depocenter basically in the Mahuangshan–Huachi–Huangling areas. The deep-water sediments were 120–320 m thick in the subsidence center, characterized by fine grain. There are differences in the mechanism between the two stages of subsidence. The early one was the response to the northward subduction of the MianLüe Ocean and intense depression under compression in Qinling during Mid-Triassic. The later subsidence is controlled by the weak extensional tectonic environment of the post-collision stage during Late Triassic.

Are Variable Screw Angle Change and Screw-to-Vertebral Body Ratio Associated With Radiographic Subsidence Following Anterior Cervical Discectomy and Fusion?

Retrospective Cohort. This study aims to assess the easily measurable radiographic landmarks of screw-to-vertebral body ratio and changes in screw angle to identify if they are associated with early subsidence following an Anterior cervical discectomy and fusion (ACDF). A retrospective cohort study was conducted on patients undergoing 1-3 level ACDF with allograft or PEEK cages. Preoperative, immediate postoperative, and 6-month postoperative radiographs were analyzed to measure intradiscal height (or distance between 2 vertebral bodies) as an anterior vertebral distance (AVD), middle (MVD), and posterior (PVD), screw angle, screw-to-vertebral body length ratio, and interscrew distance. Multivariate stepwise regression analyses were performed. 92 patients were included (42 single-level, 32 two-level, and 18 3-level ACDFs). In single-level ACDFs, a decrease in the caudal screw angle was associated with a decrease in AVD (=.001) and MVD (P = .03). A decrease in the PVD was associated with a decrease in segmental lordosis (P < .001). For two-level ACDFs, a higher caudal screw-to-body ratio was associated with a lower MVD (P = .01). Six months following an ACDF for degenerative pathology, a decrease in the caudal screw angle was associated with an increase in radiographic subsidence at the antero-medial aspect of the disc space albeit largely subclinical. This suggests that the caudal screw angle change may serve as a reliable radiographic marker for early radiographic subsidence. Furthermore, a greater screw-to-vertebral body ratio may be protective against radiographic subsidence in two-level ACDF procedures.

Expandable cages that expand both height and lordosis provide improved immediate effect on sagittal alignment and short-term clinical outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

Failure to restore lordotic alignment is not an uncommon problem following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF), even with expandable cages that increase disc height. This study aims to investigate the effect of the expandable cage that is specifically designed to expand both height and lordosis. We evaluated the outcomes of MIS TLIF in restoring immediate postoperative sagittal alignment by comparing two different types of expandable cages. One cage is designed to solely increase disc height (Group H), while the other can expand both height and lordosis (Group HL). Patients undergoing MIS TLIF using expandable cages were retrospectively reviewed, including 40 cases in Group H and 109 cases in Group HL. Visual analog scores of back and leg pain, and Oswestry disability index were collected. Disc height, disc angle, and sagittal alignment were measured. Complications were recorded, including early subsidence which was evaluated with computed tomography. Clinical and radiographic outcomes significantly improved in both groups postoperatively. Group HL showed superior improvement in segmental lordosis (4.4°±3.5° vs. 2.1°±4.8°, P=0.01) and disc angle (6.3°±3.8 vs. 2.2°±4.3°, P<0.001) compared to Group H. Overall incidence of early subsidence was 23.3%, predominantly observed during initial cases as part of the learning curve, but decreased to 18% after completion of the first 20 cases. Expandable cages with a design specifically aimed at increasing lordotic angle can provide favorable outcomes and effectively improve immediate sagittal alignment following MIS TLIF, compared to conventional cages that only increase in height. However, regardless of the type of expandable cage used, it is crucial to avoid applying excessive force to achieve greater disc height or lordosis, as this may contribute to subsidence and a possible reduction in lordotic alignment restoration. Long-term results are needed to evaluate the clinical outcome, fusion rate, and maintenance of the sagittal alignment.

WITHDRAWN: Risk Factors for Early Subsidence of 3D Printed Artificial Vertebral After Anterior Cervical Corpectomy and Fusion

This article has been withdrawn at the request of the author(s) and/or editor. After numerous emails to corresponding author and co-authors, over several months, there has been no response via email nor any attempt to answer the queries that are associated with the page proofs. Thus this article has been withdrawn from publication. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/policies/article-withdrawal.

Does Preoperative Radiation Therapy Performed for Metastatic Spine Cancer at the Cervical Spine Increase Perioperative Complications of Anterior Cervical Surgery?

Radiation therapy (RT) performed before anterior cervical spine surgery (ACSS) may cause fascial plane fibrosis, decreased soft-tissue vascularity, and vertebral body weakness, which could increase the risk of esophageal and major vessel injuries, wound complications, and construct subsidence. Therefore, this study aimed to evaluate whether preoperative RT performed for metastatic spine cancer (MSC) at the cervical spine increases perioperative morbidity for ACSS. Forty-nine patients who underwent ACSS for treatment of MSC at the cervical spine were retrospectively reviewed. All the patients underwent anterior cervical corpectomy via the anterior approach. Patient demographics, surgical factors, operative factors, and complications were recorded. Results of patients who were initially treated with RT before ACSS (RT group) were compared with those who did not receive RT before ACSS (non-RT group). Eighteen patients (36.7%) were included in the RT group, while the remaining 31 (63.3%) were included in the non-RT group. Surgery-related factors, including operation time (p = 0.109), estimated blood loss (p = 0.246), amount of postoperative drainage (p = 0.604), number of levels operated (p = 0.207), and number of patients who underwent combined posterior fusion (p = 0.768), did not significantly differ between the 2 groups. Complication rates, including esophageal injury, dural tear, infection, wound dehiscence, and mechanical failure, did not significantly differ between the RT and non-RT groups. Early subsidence was significantly greater in the non-RT group compared to that in the RT group (p = 0.012). RT performed before surgery for MSC does not increase the risk of wound complication, mechanical failure, or vital structure injury during ACSS. The surgical procedural approach was not complicated by previous RT history. Therefore, surgeons can safely choose the anterior approach when the number of levels or location of MSC favors anterior surgery, and performing a posterior surgery is unnecessary due to a concern that previous RT may increase complication rates of ACSS.

Incidence and Predictors of Subsidence Using Modular, Tapered, Fluted Titanium Femoral Stems in Aseptic Revision Total Hip Arthroplasty

BackgroundTapered, fluted titanium (TFT) femoral stems have become the gold standard in revision total hip arthroplasty (rTHA). However, there is a paucity of data on TFT stem subsidence rates following aseptic rTHA. Subsidence can lead to instability, mechanical failure, leg-length discrepancy, and may require revision surgery. This study evaluated the incidences and predictors of TFT subsidence in aseptic rTHA. MethodsA total of 102 TFT femoral stems of 4 designs were retrospectively reviewed. Stem subsidence was measured on digital radiographs taken immediately after surgery and at standard clinical follow-up. Patient characteristics, risk factors for subsidence, revision etiologies, and implant characteristics were recorded. Patient-reported outcome measures were also evaluated for a subset of cases. ResultsOverall, 12% of stems subsided >1 cm, and subsidence was minimal (<3 mm) in ≥64% of cases. From immediate postoperative to 1-month radiographic follow-up, 79% of stems subsided a mean of 2.9 mm (range, 0.1 to 12 mm). Beyond 1 month, subsidence was minimal for ≥77% of cases. In multivariate analyses, women and less femoral implant canal fill were associated with greater subsidence (P ≤ .034). The TFT stem design was not associated with early subsidence (P = .816). There were no modular junction fractures. There were 2 fractures and 2 subsidence-related revisions for aseptic loosening that occurred postoperatively. ConclusionsThe amount of subsidence in TFT stems was low and was detectable in the early (less than 1 year) postoperative period. Maximizing TFT stem fill within the femoral canal appears to reduce the risk of subsidence without increasing femoral fracture rates and should be the goal with implantation of these devices. Level of EvidenceIV–Case Series, No Control Group.

EARLY TIBIAL SUBSIDENCE OF THE CEMENTLESS OXFORD UNICOMPARTMENTAL KNEE ARTHROPLASTY

AbstractIntroductionAnecdotal reports suggest some cementless Oxford Unicompartmental Knee Replacements (OUKRs) have painful early subsidence of the tibial component with valgus rotation and/or posterior tilting. The incidence of subsidence and its association with pain is poorly understood. This radiographic study aimed to evaluate the incidence of tibial subsidence and five-year patient reported outcome measures (PROMs) of a cementless OUKR cohort.MethodologyCementless OUKRs from a high-volume centre with acceptable post-operative and five-year radiographs were included. Subsidence was determined by measuring the angle of the tibial tray/tibial axis angle and distance between the tibial tray axis and fibula head on anteroposterior and lateral radiographs using a custom MATLAB program. Analysis of 5-year PROMs assessed the relationship between subsidence and pain. Radiographs indicating tibial subsidence were validated by two observers.ResultsRadiographs of 94 cementless OUKRs were analysed of which five tibial components had subsided (incidence=5%) with an average of 1.92° varus rotation and 2.97° posterior tilt. Subsidence appeared to occur within the first post-operative year with all tibial components fixed securely at 5 years. Two subsiders had moderate pain (ICOAP=20.5,15.9, AKSS Pain=20,45) and lower Oxford Knee Scores (OKS=26,31) compared to the cohort means (ICOAP=3.91, AKSS Pain=45.9, OKS = 43.6). These two subsiders had BMIs greater than 30.ConclusionThis study found 5% of cementless OUKRs in the cohort underwent tibial subsidence. Subsidence with moderate pain occurred in 2% of cases, and pain may be associated with obesity. A larger study is needed to study subsidence in greater detail.

Migration Characteristics of a Proximally Coated Collarless Femoral Stem: A Prospective 2-Year Radiostereometric Analysis Study.

Collared femoral stems have been considered to reduce the risk of early subsidence over collarless stems. However, with advances in material technology, new surface treatments have been introduced into cementless stem design to enhance primary fixation and long-term stability. This study aims to analyze the early migration behaviors of a proximally coated collarless femoral stem and cementless acetabular component and compare the outcomes with commercially available cementless stems and acetabular cups. A total of 24 patients (25 hips) undergoing total hip arthroplasty were recruited and followed up for 2years. All patients received a Masterloc femoral stem (Medacta International SA, Castel San Pietro, Switzerland) and an Mpact acetabular component (Medacta International SA, Castel San Pietro, Switzerland) with tantalum beads embedded during the operation. Radiographs for radiostereometric analysis were taken immediately postsurgery, 6-months, 1-year, and 2-years postoperatively. The median condition number for this study was 59. The median stem subsidence was-0.08 mm (-2.47 to 0.40) at 2 years. The median cup subsidence was-0.03 mm (-0.38 to 0.57) at 2 years. The migration of the Masterloc stem was less than that of other cementless collarless, as well as collared stems, as reported in literature. This study has demonstrated the high stability and fixation provided with the use of a collarless cementless stem. The subsidence seen in both this cementless femoral stem and acetabular cup at 2 years postoperative was below the range reported in literature for cementless collarless and collared stems.

Subsidence in Centraliser Sign: A Novel Tool to Help Predict Early Subsidence in Periprosthetic Femoral Fractures Around Polished Tapered Stems Treated With Internal Fixation.

Background When treating periprosthetic femoral fractures (PPF) around polished taper slip stems (PTS), determining which patients can be successfully treated with internal fixation can be challenging. We have described the subsidence-in-centraliser (SINC) sign as a radiographic feature of PPF around PTS stems. We hypothesise that a positive SINC sign can help predict a poorer outcome for the fixation of these fractures. Patients and methods Retrospective identification of PPFs around cemented PTS with an appreciable centraliser on radiographs was conducted at a single centre. A positive SINC sign was defined as a post-injury radiograph demonstrating >50% reduction in the radiographic lucency representing the stem centraliser when compared to pre-injury films or complete obliteration of distal lucency when no pre-injury film was available. The primary outcome was the rate of subsequent stem subsidence on follow-up radiographs comparing SINC-positive and SINC-negative fractures, which were managed with open reduction and internal fixation (ORIF). Results Fifty-four patients were included in the analysis. The mean age was 76.8 years, and the mean follow-up for all patients was 12.7 months. Thirty-five fractures were deemed SINC-positive, and 19 were SINC-negative. 17/17 (100%) SINC-positive fractures managed with fixation underwent further subsidence (mean 5.4 mm, SD 2.8). A positive SINC sign demonstrated a sensitivity of 90.5% and specificity of 100% for subsequent stem subsidence in fractures treated without revision. SINC positive fractures underwent significantly more subsidence compared with SINC negative fractures when fixed (5.4 mm vs. 0.28 mm, U = 6.50, p<0.001) at a mean follow-up of 12.7 months. The SINC sign demonstrated strong inter- (k=0.96) and intra-rater (k=0.86) reliability. Conclusion The SINC sign can serve as a useful adjunct in the decision to fix or revise PPF around PTS. A positive SINC sign may represent a cement mantle that cannot be reconstituted anatomically, leading to subsidence after treatment with ORIF.

Less early subsidence of cemented Exeter short stems compared with cemented Exeter standard stems in Dorr type A femurs.

The Exeter short stem was designed for patients with Dorr type A femora and short-term results are promising. The aim of this study was to evaluate the minimum five-year stem migration pattern of Exeter short stems in comparison with Exeter standard stems. In this case-control study, 25 patients (22 female) at mean age of 78 years (70 to 89) received cemented Exeter short stem (case group). Cases were selected based on Dorr type A femora and matched first by Dorr type A and then age to a control cohort of 21 patients (11 female) at mean age of 74 years (70 to 89) who received with cemented Exeter standard stems (control group). Preoperatively, all patients had primary hip osteoarthritis and no osteoporosis as confirmed by dual X-ray absorptiometry scanning. Patients were followed with radiostereometry for evaluation of stem migration (primary endpoint), evaluation of cement quality, and Oxford Hip Score. Measurements were taken preoperatively, and at three, 12, and 24 months and a minimum five-year follow-up. At three months, subsidence of the short stem -0.87 mm (95% confidence interval (CI) -1.07 to -0.67) was lower compared to the standard stem -1.59 mm (95% CI -1.82 to -1.36; p < 0.001). Both stems continued a similar pattern of subsidence until five-year follow-up. At five-year follow-up, the short stem had subsided mean -1.67 mm (95% CI -1.98 to -1.36) compared to mean -2.67 mm (95% CI -3.03 to -2.32) for the standard stem (p < 0.001). Subsidence was not influenced by preoperative bone quality (osteopenia vs normal) or cement mantle thickness. The standard Exeter stem had more early subsidence compared with the short Exeter stem in patients with Dorr type A femora, but thereafter a similar migration pattern of subsidence until minimum five years follow-up. Both the standard and the short Exeter stems subside. The standard stem subsides more compared to the short stem in Dorr type A femurs. Subsidence of the Exeter stems was not affected by cement mantle thickness.

Subsidence of monoblock and modular titanium fluted tapered stems in revision hip arthroplasty: A retrospective multicentre comparison study

BackgroundTapered, fluted, titanium (TFT) stems have shown good clinical outcomes in revision total hip arthroplasty (rTHA), however concerns exist regarding early subsidence. This study compares subsidence between a modern monoblock 3-degree and a modular 2-degree TFT stem in rTHA. MethodsA retrospective, international multicentre comparative study was conducted including 64 rTHA in 63 patients. A monoblock TFT stem was used in 37 cases and a modular TFT stem was used in 27 cases. Patient demographics, Paprosky femoral bone loss classification, bicortical contact and stem subsidence were recorded at minimum four week follow up. ResultsThere was no statistically significant difference in overall subsidence (p = 0.318) or the rate of subsidence >10 mm between stems. Mean subsidence was 2.13 mm in the monoblock group and 3.15 mm in the modular group. Two stems subsided >10 mm: one in each group. There was no difference in bicortical contact between groups (p = 0.98). No re-revisions were performed. ConclusionsWe found no difference in subsidence between the two stems. Surgeons may consider the use of monoblock stems in rTHA as they have comparably low rates of subsidence and eliminate the small but potentially catastrophic risk of implant fracture at modular junctions associated with modular stems.

Low cervical vertebral CT value increased early subsidence of titanium mesh cage after anterior cervical corpectomy and fusion

Study designThis study was a retrospective review.ObjectiveTo study the predictive effect of Hounsfield units (HU) value in the cervical vertebral body derived from computed tomography (CT) on the early titanium mesh cage (TMC) subsidence after anterior cervical corpectomy and fusion (ACCF).MethodsThis retrospective study was conducted on patients who underwent ACCF at one institution between January 2014 and December 2018. We collected date included age, gender, body mass index (BMI), disease type, surgical segment, whether merge ACDF, HU value of the vertebral body and endplate, vertebral body height loss, cervical lordosis angle, and cervical sagittal alignment. VAS, JOA, and NDI were used to assess clinical efficacy. Univariate analysis was performed to screen the influencing factors of TMC subsidence, and then logistic regression was used to find out the independent risk factors. The ROC curve and area under curve (AUC) were used to analyze the HU value to predict the TMC subsidence.ResultsA total of 85 patients who accepted ACCF were included in this study, and early titanium mesh cage subsidence was demonstrated in 29 patients. The subsidence rate was 34.1%. The JOA, VAS, and NDI scores significantly improved in both groups after the operation. Between the subsidence and non-subsidence groups, there were significant differences in age, intervertebral distraction height, and HU value in both upper and lower vertebral body and endplate. The logistic regression analysis proved that the HU value of the lower vertebral body was an independent risk of TMC subsidence, the AUC was 0.866, and the most appropriate threshold of the HU value was 275 (sensitivity: 87.5%, specificity: 79.3%).ConclusionPreoperative cervical CT value is an independent correlative factor for early TMC subsidence after ACCF, and patients with a low CT value of the inferior vertebral body of the operative segment have a higher risk of TMC subsidence in the early postoperative period.Trial registration: This study is undergoing retrospective registration.

Hydrocarbon Accumulation Model Controlled by Overpressure Evolution in the Kelasu Thrust Belt of the Kuqa Depression, NW China

Abstract The Kuqa Depression is the most representative overpressured hydrocarbon accumulation area in western China. The early rapid subsidence since 5 Ma and the strong uplift in the late period have led to a complicated evolution history of the overpressure. Three hydrocarbon charging episodes of Cretaceous in Kuqa Depression were identified based on petrography, microthermometry of fluid inclusions, and fluorescence spectroscopy characteristics. Low-maturity oil, represented by hydrocarbon inclusions with yellow-green-yellow fluorescence, entered the reservoir at circa 5-3 Ma, whereas high-maturity hydrocarbons, as indicated by hydrocarbon inclusions with blue-green-blue fluorescence, charged the reservoir at circa 3-1.2 Ma. Pure gas inclusions with nonfluorescence represented one episode of gas charging from approximately 1.2 Ma to the present. By applying the PVTX simulation method of inclusions, the paleo-pressure evolution of formations was reconstructed, that is, the three-stage model of pressurization-release-pressurization. The coupling relationship between the paleo-pressure evolution of formations and the history of hydrocarbon charging at different stages was reconstructed. This conformed to a compound overpressure-controlled hydrocarbon accumulation model with oil convergence in the early period, oil adjustment along the fracture in the middle period, and rapid gas charging in the late period.

Direct anterior approach hip arthroplasty: How to reduce complications - A 10-years single center experience and literature review.

BACKGROUNDThe direct anterior approach for total hip arthroplasty (DAA-THA) is increasing in popularity due to some advantages such as less surgical trauma, minimal dissection of soft tissues, shorter rehabilitation times, faster return to daily activities, lower incidence of dislocation. On the other hand, the literature reports a high rate of intraoperative complications, with many different rates and complication types in the published papers. AIMTo analyze our complications comparing results with the literature; to report measures that we have taken to reduce complications rate.METHODSAll DAA-THA patients with one year minimum follow up who were operated at a single high-volume centre, between January 2010 and December 2019 were included in this retrospective study. All surgeries were performed using cementless short anatomical or straight stems and press fit cups. Patients’ follow-up was performed, at 6 wk, 3 mo, then annually post-surgery with clinical and radiological evaluation. Primary outcomes were stem revision for aseptic loosening and all-cause stem revision. Second outcome was intra-operative and post-operative complications identification.RESULTSA total of 394 patients underwent DDA-THA from January 2010 and December 2019, for a total of 412 hips; twelve patients lost to follow-up and one patient who died from causes not related to surgery were excluded from the study. The average age at the time of surgery was 61 years (range from 28 to 78 years). Mean follow-up time was 64.8 mo (range 12-120 mo). Seven stems were revised. One cortical perforation, one trochanteric and lateral cortical wall intraoperative fracture, one diaphyseal fracture, three clinically symptomatic early subsidence and one late aseptic loosening. We also observed 3 periprosthetic fractures B1 according to the Vancouver Classification. Other minor complications not requiring stem revision were 5 un-displaced fractures of the calcar region treated with preventive cerclage, one early infection, one case of late posterior dislocation, 18 case of asymptomatic stem subsidence, 6 cases of lateral cutaneous femoral nerve dysesthesia.CONCLUSIONDAA is associated to good outcomes and lower incidence of dislocation. Complication rate can be reduced by mindful patient selection, thorough preoperative planning, sufficient learning curve and use of intraoperative imaging.

Tapered wedge stems decrease early postoperative subsidence following cementless total hip arthroplasty in Dorr type C femurs compared to fit-and-fill stems

BackgroundTo compare the degree of stem subsidence between two different femoral component designs and to determine the risk factors associated with stem subsidence after cementless total hip arthroplasty (THA) in Dorr type C femurs.MethodsWe retrospectively reviewed 104 consecutive hips in 100 patients with Dorr type C proximal femoral morphology who underwent primary cementless THA using a fit-and-fill stem or a tapered wedge femoral stem at our institution between January 2012 and June 2021. A fit-and-fill stem was used in 55 hips and a tapered wedge stem was used in 49 hips. Radiologically, the distance between the apex of the major trochanter and the stem shoulder were measured at three different time points (immediately [0W], one week [1W], and six weeks [6W] after surgery) and the degrees of stem subsidence were assessed by comparing the distance between 0 and 1W, 1W and 6W, and 0W and 6W, respectively.ResultsThe mean degree of stem subsidence (0W vs. 1W) was 0.24 mm (standard deviation [SD] 0.36) in the fit-and-fill stem group, and 0.23 mm (SD 0.41) in the tapered wedge stem group. There was no significant difference between the two groups (P = 0.4862). However, the mean degrees of subsidence were significantly higher in the fit-and-fill stem group (1W vs. 6W, 0.38 mm [SD 0.68]; 0W vs. 6W, 0.65 mm [SD 0.87]) than in the tapered wedge stem group (1W vs. 6W, 0.16 mm [SD 0.32]; 0W vs. 6W, 0.24 mm [SD 0.38]) (P < 0.05 for both). In addition, the rates of > 3 mm subsidence (in which instability can be observed) were 18.2% (10 of 55 hips) and 2.0% (1 of 49 hips), respectively. There was also a significant difference between the two stems (P = 0.0091). Multivariate analysis demonstrated that fit-and-fill stem was a risk factor for > 3 mm subsidence after THA in Dorr type C femurs (P = 0.0050).ConclusionOur findings suggest that the tapered wedge stem is more suitable for Dorr type C femurs than the fit-and-fill stem to avoid early postoperative subsidence in cementless THA.

Proximal tibial bone loss in the first 2 years after unicondylar knee arthroplasty: Anatomical pattern, predictors and clinical correlation

BackgroundTibial stress fracture, anteromedial bone pain, and early subsidence could occur after unicondylar knee arthroplasty (UKA). The change in metaphyseal tibial bone density (MTBD) in the coronal and sagittal planes after UKA might be a contributing factor, but this has rarely been investigated. The aim of this study was to assess the regional and temporal change in MTBD in the coronal and sagittal planes in the first 2 years after UKA. MethodsPatients with fixed-bearing medial UKA were recruited. The change in MTBD in the first 24 months after UKA using digital radiological densitometry (DRD) was measured. Potential predictors and clinical correlations were analyzed. ResultsEighty-four cases (female 60%) were selected for review. The follow up time was 63 (±17) months. Anterior and medial regions had the largest proportion of cases with MTBD reduction (90–97%, P < 0.05). Reduction was largest at anterior and medial regions (21–29%, P < 0.05) and smallest at posterior and lateral regions (5–15%, P < 0.05). Maximal reduction occurred at 12 months for the medial region and 24 months for the anterior region. MTBDs of both regions were not significantly influenced by any confounding factors. Significant correlation was found between medial MTBD and Function Score at 6 months. ConclusionsBone loss in a zonal pattern occurs in the first 2 years after UKA with the largest loss in the anterior region below the tibial tray. It is not affected by body mass index, perioperative alignment, or angle of correction. This suggests a physiological response to trauma other than a mechanical response to the change in bone strain.

The Use of Micro Retractor in Endoscopic Endonasal Posterior Pseudocapsule Resection of Pituitary Macroadenoma. Technical Note.

BackgroundThe endoscopic endonasal approach and extra-pseudocapsule resection may be the main progress in modern pituitary surgery. However, for pituitary macroadenomas, discerning the pseudocapsule in the posterior plane of the tumor may be difficult. When the anterior-inferior debulking is performed, the early subsidence of the thinning normal pituitary gland and enlarged diaphragm may obstruct the surgical dissection view.MethodWe describe the technique of using a micro retractor for the endoscopic endonasal posterior pseudocapsule resection of pituitary macroadenomas. This micro retractor that was 2 mm in width was placed at the 12 o’clock position on the nostrils, and the end was fixed in the flexible arms of the self-retaining retractor system. The head of the micro retractor elevated the herniated diaphragm sellae in order to continue the posterior pseudocapsule resection of the pituitary macroadenoma.ResultThe technique was performed very easily and no complication was observed.ConclusionThe use of this micro retractor can increase the view of the posterior margin of the adenomas to facilitate the pseudocapsule dissection.

75. Evaluation of cage subsidence in standalone lateral lumbar interbody fusion: Novel 3D printed titanium versus polyetheretherketone (PEEK) cage

<h3>BACKGROUND CONTEXT</h3> Lateral lumbar interbody fusion (LLIF) is a common treatment for degenerative spine diseases. However, implant subsidence is a prevalent complication especially in stand-alone cases, which can negatively affect patient outcomes. The novel 3D-printed titanium (Ti) cages with porous architecture are reportedly more osteoconductive, maximize bone-to-implant contact, and have more compressive shear strength under physical force. Nevertheless, the subsidence rate of these new Ti cages compared to polyetheretherketone (PEEK) cages has not been investigated in standalone cases. <h3>PURPOSE</h3> This study aims to compare the early subsidence rate (6-12 months) of standalone Ti vs PEEK interbody cages after LLIF. <h3>STUDY DESIGN/SETTING</h3> Retrospective study. <h3>PATIENT SAMPLE</h3> A total of 113 patients and 186 levels. <h3>OUTCOME MEASURES</h3> Early cage subsidence. <h3>METHODS</h3> A retrospective study of 113 patients (186 levels) who underwent LLIF surgery with Ti or PEEK cages was conducted. Early subsidence was measured in each treated level using the Marchi et al. classification in radiographs or CT scans acquired at 6-12 months follow-up. Multivariate logistic regression analyses with generalized mixed models, setting subsidence as the outcome variable and including cage type (Ti vs PEEK) as well as significant and trending variables (p<0.10) in univariate analyses, was conducted. <h3>RESULTS</h3> In total, 51 female and 62 male patients were analyzed. The median (IQR) age at surgery was 60.0 (51.0-70.0) years. Of the 186 levels, 119 levels were treated using PEEK and 67 levels with Ti cages. The overall subsidence rate for Grades I-III was significantly less in the Ti vs the PEEK group (p=0.003). For high-grade subsidence (Grade II or III), Ti cages also demonstrated a subsidence rate (3.0%) that was significantly less compared to PEEK cages (18.5%)(p= 0.002). Multivariate analysis showed that patients treated with Ti cages were less likely to develop severe subsidence compared to those treated with PEEK (OR= 0.05, 95%CI= 0.01, 0.30)(p= 0.001). <h3>CONCLUSIONS</h3> Our study demonstrated that 3D-printed novel Ti cages had a significantly lower early subsidence rate compared to PEEK cages in standalone LLIF patients. <h3>FDA DEVICE/DRUG STATUS</h3> Titanium and PEEK Cage (Approved for this indication).

Evaluation of cage subsidence in standalone lateral lumbar interbody fusion: novel 3D-printed titanium versus polyetheretherketone (PEEK) cage.

This study aims to compare the early subsidence rate (6-12months) of standalone novel 3D-printed titanium (Ti) versus polyetheretherketone (PEEK) interbody cages after lateral lumbar interbody fusion (LLIF). A retrospective study of 113 patients (186 levels) who underwent LLIF surgery with Ti or PEEK cages was conducted. Early subsidence was measured in each treated level using the Marchi et al. classification in radiographs or CT scans acquired at 6-12months follow-up. Multivariate logistic regression analyses with generalized mixed models, setting subsidence as the outcome variable and including cage type (Ti vs PEEK) as well as significant and trending variables (p < 0.10) in univariate analyses, were conducted. In total, 51 female and 62 male patients were analyzed. The median [IQR] age at surgery was 60.0 [51.0-70.0] years. Of the 186 levels, 119 levels were treated using PEEK and 67 levels with Ti cages. The overall subsidence rate for Grades I-III was significantly less in the Ti versus the PEEK group (p = 0.003). For high-grade subsidence (Grade II or III), Ti cages also demonstrated a subsidence rate (3.0%) that was significantly less compared to PEEK cages (18.5%) (p = 0.002). Multivariate analysis showed that patients treated with Ti cages were less likely to develop severe subsidence compared to those treated with PEEK (OR = 0.05, 95% CI = 0.01, 0.30) (p = 0.001). Our study demonstrated that 3D-printed novel Ti cages had a significantly lower early subsidence rate compared to PEEK cages in standalone LLIF patients.