Novel AI-Based Algorithm for the Automated Measurement of Cervical Sagittal Balance Parameters. A Validation Study on Pre- and Postoperative Radiographs of 129 Patients.

STUDY DESIGN: Retrospective, mono-centric cohort research study. OBJECTIVES: The analysis of cervical sagittal balance parameters is essential for preoperative planning and dependent on the physician's experience. A fully automated artificial intelligence-based algorithm could contribute to an objective analysis and save time. Therefore, this algorithm should be validated in this study. METHODS: Two surgeons measured C2-C7 lordosis, C1-C7 Sagittal Vertical Axis (SVA), C2-C7-SVA, C7-slope and T1-slope in pre- and postoperative lateral cervical X-rays of 129 patients undergoing anterior cervical surgery. All parameters were measured twice by surgeons and compared to the measurements by the AI algorithm consisting of 4 deep convolutional neural networks. Agreement between raters was quantified, among other metrics, by mean errors and single measure intraclass correlation coefficients for absolute agreement. RESULTS: ICC-values for intra- (range: .92-1.0) and inter-rater (.91-1.0) reliability reflect excellent agreement between human raters. The AI-algorithm could determine all parameters with excellent ICC-values (preop:0.80-1.0; postop:0.86-.99). For a comparison between the AI algorithm and 1 surgeon, mean errors were smallest for C1-C7 SVA (preop: -.3 mm (95% CI:-.6 to -.1 mm), post: .3 mm (.0-.7 mm)) and largest for C2-C7 lordosis (preop:-2.2° (-2.9 to -1.6°), postop: 2.3°(-3.0 to -1.7°)). The automatic measurement was possible in 99% and 98% of pre- and postoperative images for all parameters except T1 slope, which had a detection rate of 48% and 51% in pre- and postoperative images. CONCLUSION: This study validates that an AI-algorithm can reliably measure cervical sagittal balance parameters automatically in patients suffering from degenerative spinal diseases. It may simplify manual measurements and autonomously analyze large-scale datasets. Further studies are required to validate the algorithm on a larger and more diverse patient cohort.

How Does Anxiety and Depression Affect the Outcome after Periradicular Infiltration Therapy?-A Retrospective Analysis of Patients Undergoing CT-Guided Single-Level Nerve Root Infiltration Due to Chronic Monoradicular Pain.

The aim of this study was to research the influence of psychological confounders on patient-reported outcomes (PROs) after lumbar infiltration therapies of periradicular infiltrations (PRI). Patients who underwent PRI in a single center between June 2018 and December 2019 were included. PRI was performed in patients with predominantly unilateral lumbar radiculopathy which existed for at least 6 weeks based on single-level nerve root compression (caused by a herniated disc, stenosis of the lateral recess, or neuroforamen), confirmed by morphological imaging. The numeric pain rating scale (NRS) for back pain (BP) and leg pain (LP) and the Oswestry Disability Index (ODI) were assessed preinterventionally, on the first day (only NRS) and at 6 weeks, and then 3, 6, and 12 months postinterventionally. The minimally clinically important difference (MCID) served as the threshold for the therapeutic effectiveness evaluation. The health-related quality of life (SF-36) was recorded preinterventionally and after 12 months. Based on the Hospital Anxiety and Depression Scale, the patients were dichotomized into depressed or nondepressed and anxious or nonanxious. Categorical data were evaluated using Fisher's exact test, and continuous data were evaluated using Student's t test. Separate linear mixed models were built to estimate the effect of anxiety or depression on repeatedly measured PROs following PRI. Data were analyzed using SPSS software. The analysis included 102 patients. Most mean baseline PROs were significantly worse in anxious or depressed patients than in nonanxious or nondepressed patients: Anxiety NRS-BP (p = 0.007), ODI (p < 0.001); Depression NRS-BP (p = 0.026), NRS-LP (p < 0.001), ODI (p < 0.001). All patients showed a clinically meaningful reduction in pain and functional improvement over a 12-month follow-up. There was no significant difference in the estimated overall mean PRO between all patients (p > 0.05). In conclusion, anxiety and depression are associated with worse PROs before and after PRI. However, patients with underlying depression or anxiety can expect a similar gain in PRO compared to patients without depressive or anxious symptoms.

Association between posterior tibial slope and anatomic spinopelvic parameters: a retrospective cross-sectional study.

PURPOSE: Only a few publications considered the influence of the spinopelvic parameters on below-hip anatomy. There is a lack of evidence about the relationship between the anatomic spinopelvic parameters and the posterior tibial slope (PTS). Therefore, the aim of this study was to analyze the association between fixed anatomic spinopelvic parameters and PTS. METHODS: Adult patients presenting with lumbar, thoracic, or cervical complaints together with knee pain at a single hospital between 2017 to 2022 with available standing full-spine lateral radiograph and lateral knee radiograph were retrospectively reviewed. The measured parameters included the pelvic incidence (PI), the sacral kyphosis (SK), the pelvisacral angle, the sacral anatomic orientation (SAO), the sacral table angle, the sacropelvic angle and the PTS. Pearson's correlations and linear regression analyses were conducted. RESULTS: A total of 80 patients (44 women), median age 63 years were analyzed. A strong positive correlation was identified between PI and PTS (r = 0.70, p < 0.001). A strong negative correlation was observed between PI and SAO (r = - 0.74, p < 0.001). A strong positive correlation was observed between PI and SK (r = 0.81, p < 0.001). A univariable linear regression analysis showed that PTS can be deduced from PI according to the following formula: PTS = 0.174 × PI - 1.138. CONCLUSION: This study is the first to support a positive correlation between the PI and the PTS. We demonstrate that knee anatomy is individually correlated to pelvic shape and therefore influences spinal posture.

A Retrospective Analysis of the Association Between Male Facial Hair and the Incidence of Peri-Prosthetic Infections.

Background: The wearing of male facial hair has been undergoing something of a renaissance for a number of years, with medical colleagues in the surgical disciplines being no exception. Meanwhile, there are a few reports in the literature that beards might have an increased bacterial colonization. This study aims to determine if wearing a beard leads to an increased rate of infection in total hip or knee arthroplasty. Patients and Methods: A retrospective analysis was performed on 20,394 primary hip and knee replacements that were implanted at a single university hospital. The rate of infections that occurred within one year after surgery and the surgeons performing the surgery were recorded. The surgeons were classified into clean-shaven and beard wearers. The beard wearers were further classified by individual facial hair styles, namely a moustache, chin beard, round beard, or full beard. Results: The overall rate of surgical site infections 365 days after surgery is 0.75%. There was no statistically significant association between surgical site infection and the presence of facial hair (p = 0.774) or specific beard types (p = 0.298). Conclusions: The results presented in this study show no differences in infection rates across different facial hair styles of male surgeons.

Patient-controlled sublingual sufentanil tablet system versus intravenous opioid analgesia for postoperative pain management after lumbar spinal fusion surgery.

PURPOSE: This retrospective cohort study investigated the efficacy of a sublingual sufentanil tablet system (SSTS) in comparison to intravenous patient-controlled analgesia (IV-PCA) with piritramide for the management of postoperative pain following lumbar spinal fusion surgery. METHODS: This was a retrospective analysis of patients undergoing single- or two-level lumbar spinal fusion surgery and receiving the SSTS or IV-PCA for postoperative pain relief as part of multimodal pain management that included IV paracetamol and oral metamizole. The following variables were collected: postoperative pain intensity and frequency scores using the numerical rating scale (NRS), hospital anxiety and depression scale (HADS), occurrence of nausea, postoperative mobilization, and patient satisfaction (MacNab criteria). RESULTS: Sixty-four patients were included. Those receiving the SSTS (n = 30) had significantly lower pain intensities on the operative day (NRS: 4.0, CI: 3.6-4.3 vs. 4.5, CI: 4.2-4.9; p < 0.05) and one day postoperatively (NRS: 3.4, CI: 3.1-3.8 vs. 3.9 CI: 3.6-4.3; p < 0.05) compared to patients receiving IV-PCA (n = 34). No differences were observed on postoperative days 2 to 5. SSTS patients experienced more nausea than IV-PCA patients (p = 0.027). Moreover, SSTS patients had a higher percentage of early mobilization following surgery than IV-PCA patients (p = 0.040). Regarding patient satisfaction, no significant differences were seen between the groups. CONCLUSION: The SSTS is a potentially advantageous alternative to opioid IV-PCA for use within a multimodal approach to managing postoperative pain after lumbar fusion surgery. Furthermore, the potentially higher emetic effect of SSTS should be considered, and the patient should be able to perform the application.

Next Level in Computed Tomography-Guided Periradicular Infiltration Therapy: Same Efficiency with Less Radiation Exposure.

OBJECTIVE: This retrospective cohort study investigated the radiation exposure and clinical efficiency of a new institutional low-dose protocol for computed tomography (CT)-guided lumbar periradicular infiltration (PRI). METHODS: This was a retrospective matched-pair comparison of patients undergoing single-level lumbar PRI therapy employing a new low-dose CT protocol consisting of a helical scan with reduced energy levels and tube current versus the institutional standard CT protocol. The following variables were collected: dose-length product for the planning step, interventional step, and total examination, number of CT guidance scans, examination time, and postprocedural improvement on the numerical rating scale for radicular pain. RESULTS: Forty-five patients were allocated to each group. A sufficient radiation dose reduction of 30% during PRI was achieved with the low-dose protocol with a median dose-length product of 9.8 mGy∗cm compared to 32.9 mGy∗cm with the standard protocol (P < 0.001). No need for additional multiple scans during the interventional mode was observed in the low-dose group, resulting in a comparable procedure time between the groups. Furthermore, the short-term pain-reducing effect of PRI was comparable between the low-dose and standard protocols (median delta numerical rating scale = 4 in both groups). CONCLUSIONS: Our low-dose protocol with less tube voltage and lower electric current leads to less radiation exposure with the same safety and efficiency. In conclusion, every facility that performs CT-based procedures should check whether a further dose reduction is applicable to avoid stochastic radiation damage to the patient.

Local Infiltrations in Patients with Radiculopathy or Chronic Low Back Pain Due to Segment Degeneration-Only A Diagnostic Value?

The purpose of this study was to investigate the differences in the therapeutic effectiveness of CT-assisted infiltration of a local anesthetic + corticosteroid between nerve root and facet joint capsule in patients with chronic complaints. In this prospective trial with a 12-month follow-up, a total of 250 patients with chronic low back pain and radiculopathy were assigned to two groups. In the first group, patients with specific lumbar pain due to spondyloarthritis received periarticular facet joint capsule infiltration (FJI). In the second group, patients with monoradicular pain received periradicular infiltration (PRI) via an extraforaminal selective nerve block. Clinical improvement after FJI and PRI regarding pain (NRS), function (ODI), satisfaction (McNab), and health related quality of life (SF-36) were compared. Minimally clinically important difference (MCID) served as the threshold for therapeutic effectiveness evaluation. A total of 196 patients were available for final analysis. With respect to the pain reduction and functional improvement (ODI, NRSoverall, and NRSback), the PRI group performed significantly better (ptreatment < 0.001) and longer over time (ptreatment × time 0.001) than the FJI group. Regarding pain and function, only PRI demonstrated a durable improvement larger than MCID. A significant and durable therapeutic value was found only after receiving PRI but not after FJI in patients with chronic pain.

The Use of Iloprost in the Treatment of Bone Marrow Edema Syndrome of the Proximal Femur: A Review and Meta-Analysis.

Objective: The aim of this meta-analysis was to investigate the impact of intravenous iloprost therapy on pain, function, edema changes, and follow-up surgery in bone marrow edema syndrome of the proximal femur. Methods: A systematic literature search up to May 2022 was performed to find relevant papers that made a statement about the outcome of intravenous iloprost therapy alone. Factors such as the Visual Analog Scale (VAS), Harris Hip Score (HHS), edema reduction, and follow-up interventions were considered. These were compared using Forest plots. Results: In 11 studies, 190 proximal femora with bone marrow edema syndrome that received intravenous iloprost therapy without further therapeutic intravenous or surgical intervention such as core decompression were studied. There was a significant mean improvement in VAS by 3.3 cm (2.07−4.5 cm) (p < 0.001) and HHS by 24.36 points (18.23−30.49) (p < 0.001) 3−6 months after receiving iloprost therapy. Only in 9.3% of cases (1.1−24.3%) did no clinical or radiological improvement occur. Conclusions: It could be shown that the existing publications support intravenous therapy with iloprost in patients with bone marrow edema syndrome and result in good clinical outcomes.

Comparison of two different antiseptics regarding intracutaneous microbial load after preoperative skin cleansing in total knee and hip arthroplasties.

Periprosthetic infections (PPIs) are a serious concern in total knee and hip arthroplasty, and they have an increasing incidence. To prevent PPI, preoperative skin disinfection, as a key element of antisepsis, represents an important part of infection prevention. However, no specific antiseptic agent is endorsed by the relevant guidelines. The purpose of this retrospective, not randomized study was to investigate the difference in the residual bacteria load between an approved antiseptic with an alcohol-based solution with additional benzalkonium chloride (BAC) and an alcohol-based solution with additional octenidine dihydrochloride (OCT) at two different time periods. In 200 consecutive patients with total knee or hip arthroplasty, skin samples from the surgical sites were collected after skin disinfection with BAC (100 g solution contain: propan-2-ol 63.0 g, benzalkonium chloride 0.025 g) or OCT (100 g solution contain: octenidine dihydrochloride 0.1 g, propan-1-ol, 30.0 g, propan-2-ol 45.0 g) (100 patients per group). Following the separation of cutis and subcutis and its processing, culture was performed on different agar plates in aerobic and anaerobic environments. In the case of bacteria detection, the microbial identification was determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and the number of contaminated samples was compared between the groups. Additionally, multiple regression analysis was performed to examine the effect of the type of disinfectant, BMI, age, sex, rheumatoid arthritis, diabetes mellitus, skin disorders, smoking status, and localization of skin samples on positive bacteria detection. A total of 34 samples were positive for bacteria in the BAC group, while only 17 samples were positive in the OCT group (p = 0.005). Disinfectant type was the only significant parameter in the multiple regression analysis (p = 0.006). A significantly higher contamination rate of the subcutis was shown in the BAC group compared to the OCT group (19 vs. 9, p = 0,003). After the change from BAC to OCT in preoperative skin cleansing in the hip and knee areas, the number of positive cultures decreased by 50%, which might have been caused by a higher microbicidal activity of OCT. Therefore, the use of OCT in preoperative cleansing may reduce the risk of PPI in hip and knee surgery. Randomized controlled trials are required to confirm the effect and to evaluate if it reduces the risk of PPI.

Defining the canal for ischial and pubic screws in cup revision surgery.

PURPOSE: When revising acetabular cups, it is often necessary to provide additional stabilisation with screws. In extensive defect situations, the placement of screws caudally in the ischium and/or pubis is biomechanically advantageous. Especially after multiple revision operations, the surgeon is confronted with a reduced bone stock and unclear or altered anatomy. In addition, screw placement caudally is associated with greater risk. Therefore, the present study aims to identify and define safe zones for the placement of caudal acetabular screws. METHODS: Forty-three complete CT datasets were used for the evaluation. Sixty-three distinctive 3D points representing bone landmark of interests were defined. The coordinates of these points were then used to calculate all the parameters. For simplified visualisation and intra-operative reproducibility, an analogue clock was used, with 12 o'clock indicating cranial and 6 o'clock caudal. RESULTS: A consistent accumulation was found at around 4.5 ± 0.3 hours for the ischium and 7.9 ± 0.3 hours for the pubic bone. CONCLUSIONS: The anatomy of the ischium and pubis is sufficiently constant to allow the positioning of screws in a standardised way. The interindividual variation is low - regardless of gender - so that the values determined can be used to position screws safely in the ischium and pubis. The values determined can provide the surgeon with additional orientation intra-operatively when placing caudal acetabular screws.

Cone-Beam Navigation Can Reduce the Radiation Exposure and Save Fusion Length-Dependent Operation Time in Comparison to Conventional Fluoroscopy in Pedicle-Screw-Based Lumbar Interbody Fusion.

This study investigates the advantages and disadvantages of cone-beam-based navigated standardized posterior lumbar interbody fusion surgery (PLIF), regarding the radiation exposure and perioperative time management, compared to the use of fluoroscopy. Patients treated receiving an elective one- to three-level PLIF were retrospectively enrolled in the study. The surgery time, preparation time, operation room time, and effective dose (mSv) were analyzed for comparison of the radiation exposure and time consumption between cone-beam and fluoroscopy; Results: 214 patients were included (108 cone-beam navigated, and 106 traditional fluoroscopies). Using cone-beam navigation, reductions in the effective dose (2.23 ± 1.96 mSv vs. 3.39 ± 2.32 mSv, p = 0.002) and mean surgery time of 30 min (143.62 ± 43.87 min vs. 171.10 ± 48.91 min, p < 0.001) were demonstrated, which leveled out the extended preparation time of 7−8 min (37.25 ± 9.99 min vs. 29.65 ± 7.69 min, p < 0.001). These effects were fusion length dependent and demonstrated additional benefits in multisegmental surgeries. The cone-beam navigation system led to a reduction in the perioperative time requirements and radiation exposure. Furthermore, the controversially discussed longer preparation time when using cone-beam navigation was amortized by a shortened surgery time, especially in multilevel surgery.

Improvement of Adolescent Idiopathic Scoliosis Primary Correction by Brace Design Optimization.

(1) Background: Primary in-brace correction has been shown to be related to conservative adolescent idiopathic scoliosis (AIS) treatment outcome. The purpose of the study was to evaluate TLSO brace design changes over eight years regarding primary Cobb correction and de-rotation of the (major) curve. (2) Methods: This retrospective analysis included AIS patients treated with a full-time TLSO-brace in a single Orthopedic University hospital in 2012-2014 and 2017-2019. Brace design changes resulted from an evolutionary process, from a 3-point bending to a 3D TLSO. The brace parameters (presence of an anterior shoulder pad, posterior high-thoracic pad, thoracic space, and angle of the lumbar and thoracic pressure points) were analyzed regarding the primary (major) Cobb angle and apex rotation correction with a multivariate analysis. (3) Results: A total of 74 (63 female) patients were included in the study. The Cobb angle primary correction was significantly improved over the timeframe. The primary correction was significantly influenced by all design parameters and partially by its interactions with (curve specific) different effects on the Cobb correction and apex de-rotation. (4) Conclusions: Knowledge about the effects of brace design parameters on the curve's angle and rotation correction enables improvements in individualized brace design and the brace optimization process.

Destructive per continuitatem spondylodiscitis after endovascular abdominal or thoracic aneurysm repair (EVAR/TEVAR): rare and untreatable?

INTRODUCTION: Very few publications have previously described spondylodiscitis as a potential complication of endovascular aortic procedures (EVAR/TEVAR). We present to our knowledge the first case series of spondylodiscitis following EVAR/TEVAR based on our data base. Particular focus was laid on the complexity of disease treatment and grave outcome perspectives from a spine surgeon's point of view in this seriously affected patient group. MATERIALS AND METHODS: A retrospective analysis and chart review was performed for 11 out of 284 consecutive spondylodiscitis patients who underwent EVAR/TEVAR procedure and developed destructive per continuitatem spondylodiscitis. RESULTS: All 11 patients had single or more level destructive spondylodiscitis adjacent to the thoracic/lumbar stent graft. In mean, four surgeries were performed per patient to treat this rare complication. Six out of eleven patients (55%) died within 6 months of first identification of per continuitatem spondylodiscitis. In four patients due to persisting infection of the graft and recurrence of the abscess formation, a persisting fistula from anterior approach to the skin was applied. CONCLUSIONS: Destructive per continuitatem spondylodiscitis is a rare and severe complication post-EVAR/TEVAR. Clinical and imaging features of anterior paravertebral disease and anterior vertebral body involvement suggest direct continuous spread of the graft infection to the adjacent vertebral column. The mortality rate of these severe infections is extremely high and treatment with a permanent fistula may be one salvage procedure.

Does Total Hip Arthroplasty Influence the Development and Localization of Sacral Insufficiency Fractures?

BACKGROUND: Sacral insufficiency fractures (SIFs) are fractures related to reduced bone strength. In a previous study, we noticed that many patients with SIF had undergone total hip arthroplasty (THA). Therefore, the purpose of the present study was to research the localization of clinically apparent SIFs in relation to unilateral THA as well as the influence of unilateral THA on bone mineral density changes in the sacrum. METHODS: In this retrospective study, 171 patients with SIFs were screened for unilateral THA. In the group of patients with SIF and THA, the rate of SIF ipsilateral and contralateral to the side of the THA was determined. In a second cohort of 39 THA patients with healthy bone, changes in bone mineral density at the sacral alae ipsilateral and contralateral to the THA were analyzed by use of computed tomography immediately postoperatively and at the 1-year follow-up. RESULTS: Of the 171 patients with SIF, 50 (40 female; mean age, 79 years; range, 54 to 101 years) were previously treated with THA. Of the 50, 31 patients were treated with unilateral THA. The proportion of patients with an SIF contralateral to the THA was 42% (13 of 31) and ipsilateral to the THA was 19% (6 of 31). Twelve patients had bilateral SIFs. The mean age of the THA group without SIF was 62 years (range, 49 to 79 years); 17 were female. The median bone mineral density decreased significantly (p = 0.023), from 35.0 to 13.0 HU, at the sacral ala contralateral to the THA, whereas the decrease of ipsilateral bone mineral density, from 24.0 to 17.0 HU, was not significant (p = 0.361). CONCLUSIONS: The proportion of patients with an SIF contralateral to a THA was twice as high as that of patients with an SIF ipsilateral to a THA. These findings are supported by the second cohort's decrease in bone mineral density at the sacral ala contralateral to the THA at 1 year after surgery. We conclude that THA can lead to spatially different remodeling of the sacrum, possibly affecting the development of SIFs. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Dual-energy X-ray Absorptiometry Does Not Represent Bone Structure in Patients with Osteoporosis: A Comparison of Lumbar Dual-Energy X-Ray Absorptiometry with Vertebral Biopsies.

STUDY DESIGN: Prospective cross-sectional exploratory study. OBJECTIVE: To evaluate the correlation between in vivo lumbar dual-energy x-ray absorptiometry (DXA) and parameters of bone architecture in micro-computed tomography (micro-CT) in patients with osteoporosis. SUMMARY OF BACKGROUND DATA: DXA is the current diagnostic standard for evaluating osteoporosis. However, there are various concerns regarding its validity, especially in the spine. No study has so far investigated whether in vivo DXA correlates with the actual lumbar bone architecture. METHODS: Lumbar DXA scans were compared with micro-CT analysis of vertebral biopsies in patients with osteoporotic vertebral fractures (fracture group) and those without (control group). Preoperatively, all patients underwent a DXA scan (L1-L4). Intraoperative biopsies from nonfractured vertebrae (preferably L3) were analyzed by micro-CT regarding bone quantity and quality. The groups were compared regarding differences in DXA and micro-CT results. In each group, a correlation analysis was performed between DXA and micro-CT. RESULTS: The study included 66 patients (33 per group). Preoperative DXA results were worse in the fracture group than the control group (areal bone mineral density [aBMD] 0.95 vs. 1.31, T-score -1.97 vs. 0.92, each P < 0.001). Micro-CT analysis confirmed differences regarding quantitative parameters (bone/total volume: 0.09 vs. 0.12, P < 0.001) and qualitative parameters (connectivity index: 15.73 vs. 26.67, P < 0.001; structure model index: 2.66 vs. 2.27, P < 0.001; trabecular number: 2.11 vs. 2.28, P = 0.014) of bone architecture between both groups. The DXA results did not correlate with micro-CT parameters in the fracture group. In the control group, correlations were found for some parameters (bone/total volume vs. aBMD: r = 0.51, P = 0.005; trabecular number vs. aBMD: r = 0.56, P = 0.001). CONCLUSION: These data constitute the first comparison of DXA measurements with microstructural analysis of vertebral biopsies in patients with osteoporosis. Our results indicate that lumbar DXA neither qualitatively nor quantitatively represents microstructural bone architecture and is therefore not a reliable tool for the evaluation of bone quality in the spine.Level of Evidence: 3.

An Isoelastic Monoblock Cup Retains More Acetabular and Femoral Bone Than a Modular Press-Fit Cup: A Prospective Randomized Controlled Trial.

BACKGROUND: For cup revision after total hip arthroplasty, sufficiently good periacetabular bone stock is a prerequisite for fixation of the revision implant. Cementless cups can lead to a relevant reduction of peri-implant bone mineral density (BMD) through stress-shielding. METHODS: Fifty patients were included in this prospective randomized controlled trial. Group 1 (RM group) received an isoelastic monoblock cup (RM Pressfit vitamys; Mathys). Group 2 (IT group) received a modular titanium cup (Allofit-S IT Alloclassic with a polyethylene liner; Zimmer). Periacetabular BMD was determined and subdivided into 4 regions of interest by dual x-ray absorptiometry at 1 week (baseline) and at 4 years postoperatively. Our primary outcome was reduction in periacetabular BMD. RESULTS: Periacetabular BMD was reduced by an average of 15.1% in the RM group and 16.5% in the IT group at 4 years postoperatively. No significant difference was found between the 2 groups over the periacetabular structure as a whole. However, the decrease of BMD in the polar region was significantly different in the RM group (4.9% ± 10.0%) compared with the IT group (15.9% ± 14.9%, p = 0.005). Use of the isoelastic RM cup showed significantly less bone loss than the modular IT cup. CONCLUSIONS: Relevant loss of BMD at 4 years after surgery was identified in the periacetabular region in both groups. No differences between the 2 cup systems were found when looking at the overall periacetabular region. As a secondary outcome, less postoperative periacetabular bone loss occurred in the polar region when an isoelastic cup was used. Longer follow-up is required to allow for conclusions to be drawn about the long-term course of the 2 cup systems. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Influence of curve morphology and location on the efficacy of rigid conservative treatment in patients with adolescent idiopathic scoliosis.

AIMS: The aim of the present study was to answer the question whether curve morphology and location have an influence on rigid conservative treatment in patients with adolescent idiopathic scoliosis (AIS). METHODS: We retrospectively analyzed AIS in 127 patients with single and double curves who had been treated with a Chêneau brace and physiotherapeutic specific exercises (B-PSE). The inclusion criteria were the presence of structural major curves ≥ 20° and < 50° (Risser stage 0 to 2) at the time when B-PSE was initiated. The patients were divided into two groups according to the outcome of treatment: failure (curve progression to ≥ 45° or surgery) and success (curve progression < 45° and no surgery). The main curve type (MCT), curve magnitude, and length (overall, above and below the apex), apical rotation, initial curve correction, flexibility, and derotation by the brace were compared between the two groups. RESULTS: In univariate analysis treatment failure depended significantly on: 1) MCT (p = 0.008); 2) the apical rotation of the major curve before (p = 0.007) and during brace treatment (p < 0.001); 3) the initial and in-brace Cobb angles of the major (p = 0.001 and p < 0.001, respectively) and minor curves (p = 0.015 and p = 0.002); 4) major curve flexibility (p = 0.005) and the in-brace curve correction rates (major p = 0.008, minor p = 0.034); and 5) the length of the major curve (LoC) above (p < 0.001) and below (p = 0.002) the apex. Furthermore, MCT (p = 0.043, p = 0.129, and p = 0.017 in MCT comparisons), LoC (upper length p = 0.003, lower length p = 0.005), and in-brace Cobb angles (major p = 0.002, minor p = 0.027) were significant in binary logistic regression analysis. CONCLUSION: Curve size, location, and morphology were found to influence the outcome of rigid conservative treatment of AIS. These findings may improve future brace design and patient selection for conservative treatment. Cite this article: Bone Joint J 2021;103-B(2):373-381.

Lumbar hemivertebra resection in congenital scoliosis utilizing cone-beam navigation: less radiation, more accuracy-proof of concept.

PURPOSE: To present the first known pediatric utilization of cone-beam navigation system (CBNS) for hemivertebra resection and spondylodesis CASE PRESENTATION: A 14-year-old female with congenital scoliosis, diagnosed at 8 years of age, presenting with progressive symptoms, a Cobb angle (L3-5) of 38° at time of surgery, treated historically with conservative measures. Presence of spinal intramedullary disease was excluded prior to operation via whole spine MRI. RESULTS: Patient successfully underwent surgical correction utilizing the CBNS (O-arm™, Medtronic®). Post-operative Cobb angle (L3-5) was restored to 8°. Following four different pediatric patient's radiation exposures (two receiving correction via the O-arm platform and two via the traditional method employing fluoroscopy), we show a reduction in radiation exposure using the CBNS system. CONCLUSION: We present the first known pediatric case of the utilization of the CBNS system for hemivertebra correction. We demonstrate that utilizing the CBNS platform can not only increase surgical accuracy but also decrease pediatric patient's radiation exposure as a preoperative CT scan is not needed. Future studies should continue to explore additional benefits of implementing the system into surgical practice.

MRI following scoliosis surgery? An analysis of implant heating, displacement, torque, and susceptibility artifacts.

OBJECTIVES: The implant constructs used in scoliosis surgery are often long with a high screw density. Therefore, it is generally believed that magnetic resonance imaging (MRI) should not be carried out after scoliosis surgery, with the result that computed tomography is often preferred despite the ionizing radiation involved. The objective of this study was to evaluate the MRI compatibility of long pedicle-screw-rod constructs at 1.5 T and 3 T using standardized methods of the American Society for Testing and Materials (ASTM). METHODS: Constructs between 130 and 430 mm long were systematically examined according to the ASTM standards F2182 (radio frequency-induced heating), F2119 (susceptibility artifacts), F2213 (magnetically induced torque), and F2052 (magnetically induced displacement force). RESULTS: The maximum heating in the magnetic field was 1.3 K. Heating was significantly influenced by magnetic field strength (p < 0.001), implant length (p = 0.048), and presence of cross-links (p = 0.001). The maximum artifact width for different lengths of the anatomically bent titanium rods with CoCr alloy ranged between 14.77 ± 2.93 mm (TSE) and 17.49 ± 1.82 mm (GRE) for 1.5 T and between 23.67 ± 2.39 mm (TSE) and 27.77 ± 2.37 mm (GRE) for 3 T. TiCP and TiAl showed the smallest and CoCr and CoCr Plus the largest artifact widths. The magnetically induced torque and displacement force were negligible. CONCLUSIONS: MRI following scoliosis surgery with long implant constructs is safe with the patient in supine position. Although susceptibility artifacts can severely limit the diagnostic value, the examination of other regions is possible. KEY POINTS: • Large spinal implants are not necessarily a contraindication for MRI; MR conditional status can be examined according to the ASTM standards F2182, F2119, F2213, and F2052. • A metallic pedicle-screw-rod system could be reliably and safely examined in all combinations of length (130 to 430 mm), configuration, and material in a B0 at 1.5 T and 3 T. • According to ASTM F2503, the examined pedicle-screw-rod system is MR conditional and especially the young patients can benefit from a non-ionizing radiation MRI examination.