Applying Characteristic Impedance Compensation Cut-Outs to Full Radio Frequency Chains in Multi-Layer Printed Circuit Board Designs.

Modern wireless communication systems are of utmost importance to various sectors such as healthcare, education, the household, and the advancement of emerging technologies like the internet of things, autonomous vehicles, and the enhancement of 5G. Further development and improvement of these systems drives the need for small dimension, high integration and density, and cost-effective electronic devices. Achieving optimal performance in wireless electronic devices involves overcoming engineering challenges related to microstrip line signal integrity. This research addresses the impact of surface mount technology (SMT) component pads on signal integrity, proposing a novel high-frequency microstrip line structure for mitigating impedance discontinuities. The study introduces stepped microstrip lines and explores characteristic impedance compensation techniques. A six-layer printed circuit board (PCB) structure is presented, and the effects of compensation on signal integrity are analyzed using time-domain reflectometry and scattering parameter measurements. The results demonstrate the effectiveness of compensation methods in aligning characteristic impedance with desired values, thereby ensuring improved impedance matching and transmission coefficients. The average over-the-length impedance for the proposed structure with compensation applied was measured to be 52.7 Ω, which is only 1.3 Ω (2.5%) more than that of the reference microstrip. Applying reference plane cut-outs leads to a maximum compensated absolute value of more than 30 Ω to reach the target impedance with a 10% tolerance. This research contributes valuable insights for advancing wireless communication systems and maintaining robustness in high-frequency microstrip transmission lines.

Augmented versus non-augmented Trochanteric Fixation Nail-Advanced (TFNA) nails for treating trochanteric fractures in patients over sixty-five years of age.

PURPOSE: Intramedullary nailing is a common treatment for pertrochanteric fractures. However, implant-related mechanical failures, such as cut-out and cut-through, lead to higher rates of revision surgery, loss of autonomy, and mortality. Cemented augmentation enhances the bone-implant interface. This study compared the frequency of mechanical failures between augmented and non-augmented Trochanteric Fixation Nail-Advanced (TFNA) nails. METHODS: This descriptive, retrospective study at a level 1 trauma centre included patients aged > 65 years with pertrochanteric fractures treated by a short augmented or non-augmented TFNA nail. The primary outcome was the comparison of cut-out or cut-through rates between groups at three and six months postoperatively. RESULTS: Of the 181 patients analysed, 103 had augmented TFNA nails and 78 had non-augmented TFNA nails. There were no statistically significant differences between groups in terms of demographic characteristics, AO/OTA classification, or quality of reduction. The failure rate was significantly lower in the augmented group than in the non-augmented group: 1 (0.97%) versus 9 (11.54%) (p = 0.005). At six months postoperatively, there was no significant difference between the two groups concerning functional recovery, as measured by the Parker and EuroQoL 5-Dimensions scores. CONCLUSIONS: For patients aged over 65 years, the use of the augmented TFNA nail may reduce the risk of fixation failures such as cut-out.

Failure after intramedullary nailing for geriatric trochanteric fracture: does quality of fracture reduction on the AP and lateral planes show the same results?

PURPOSE: This study aimed to investigate the failure of trochanteric fracture fixation according to the quality of fracture reduction on the anteroposterior (AP) and lateral views. METHODS: Data from 340 female and 152 male patients ≥ 60 years of age who underwent intramedullary nailing for a trochanteric fracture between 2016 and 2020 were analysed retrospectively. The quality of fracture reduction was classified as type A, type E, and type I on the AP view and type N, type A, and type P on the lateral view according to the relative position of the proximal and distal fragments. The failure rate was evaluated and compared according to the quality of fracture reduction. The risk factors of the fixation failure were investigated by comparison of variables between patients with and without failure and by regression analysis. RESULTS: Patients with poor reduction, type I and type P had higher failure rates. However, a statistically significant difference was found only for patients with poor reduction (type P) on the lateral view (p < 0.001). Patients with failure showed significantly higher rates of poor reduction on the lateral view and AO/OTA type A3 fractures. The regression analysis also showed that poor reduction on the lateral view (odds ratio [OR] 12.70; 95% confidence interval [CI] 4.0-40.6; p < 0.001) and AO/OTA type A3 fractures (OR 5.40; 95% CI 1.24-23.49, p = 0.025) were risk factors for failure. CONCLUSION: Poor reduction such as type P reduction was associated with failure after intramedullary nailing for trochanteric fractures. Surgeons should check the quality of fracture reduction carefully with the proper fluoroscopic view to prevent failure in geriatric patients with trochanteric fractures.

A dual telescoping lag screw nailing system for intertrochanteric fractures: retrospective analysis of clinical and radiologic outcomes.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate whether this system is associated with a reduced rate of failure and complications in patients treated for proximal femoral fractures with intramedullary nailing. MATERIALS AND METHODS: 742 Patients with AO-OTA 31-A intertrochanteric fractures were enrolled at a single Institution. Functional evaluation was assessed through the Functional Independence Measure (FIM™) instrument and Parker's New Mobility Score (NMS). Radiological follow-up included the degree of the reduction according to the Baumgartner criteria, the Tip-Apex Distance, and the shortening of the telescoping screws and its lateral protrusion. RESULTS: Pre-operative mean FIM™ and NMS were 4.3 (range 1-9) and 98.7 (range 22-126), respectively. At the 12-month follow-up the average FIM™ and NMS were 95.3 (range 22-126) and 3.7 (range 1-9), respectively. Mean shortening of the lag screws was 4.3 mm (range 1-8) and mean lateral protrusion was 1.7 mm (range 0-3). 3 Cases (0.70%) of non-consolidation requiring reoperation were recorded. 1 Case (0.24%) of these cases was also characterized by nail breakage. No case of cut-out has been reported at our follow-up. CONCLUSIONS: This dual telescoping nail system is effective and safe. The sliding of the telescoping screws within the barrel is able to decrease strain from the femoral head during weight bearing reducing the risk of cut-out.

Standardized Tip-Apex Distance (STAD): a modified individualized measurement of cephalic fixator position based on its own femoral head diameter in geriatric intertrochanteric fractures with internal fixation.

OBJECTIVE: To design a standardized Tip-Apex Distance (STAD) and analyze the clinical significance of STAD in predicting cut-out in geriatric intertrochanteric fractures with internal fixation. METHODS: Firstly, we designed STAD according to the rule of TAD. We measured the STAD individually based on its own femoral head diameter (iFHD) instead of the known diameter of the lag screw in calculating TAD, resulting in that the STAD is simply the relative quantitation relationship of iFHD (the times of iFHD). In this study, we assumed that all the iFHD was 6D (1iFHD = 6D, or 1D = 1/6 of iFHD) in order for complete match of the Cleveland zone system, easy comparison of the STAD, and convenient identification for artificial intelligence. Secondly, we calculated and recorded all the STAD of cephalic fixator in 123 eligible ITF patients. Thirdly, we grouped all the ITF patients into the Failure and Non-failure groups according to whether cut-out or not, and analyzed the correlation between the cut-out and the STAD. RESULTS: Cleveland zone, Parker's ratio (AP), TAD, and STAD were associated with the cut-out in univariate analysis. However, only STAD was the independent predictor of the cut-out by multivariate analysis. No cut-out was observed when STAD ≤ 2D (1/3 of iFHD). The Receiver Operating Characteristic (ROC) curve indicated that STAD was a reliable predictor of cut-out, and the best cut-off value of STAD was 2.92D. Cut-out rate increased dramatically when STAD increased, especially when STAD > 3D (1/2 of iFHD). CONCLUSION: Essentially, the STAD is a relative quantitation relationship of iFHD. The STAD is a reliable measurement of cephalic fixator position in predicting cut-out in geriatric ITF patients with single-screw cephalomedullary nail fixations. For avoiding cut-out, the STAD should be no more than a half of iFHD. LEVEL OF EVIDENCE: Level III, Prognostic Study.

Predictors of and predictive nomogram for cut-out of proximal femur nail anti-rotation device in intertrochanteric fractures.

PURPOSE: This study determined independent predictors and developed a predictive nomogram for failed correction of intertrochanteric fractures due to cut-out of the proximal femur nail anti-rotation (PFNA) device. METHODS: Demographic and radiological data of 592 adult patients with intertrochanteric fractures (AO 31A) treated by PFNA were collected retrospectively. Independent predictors of cut-out were obtained through univariate and multivariate analyses, and a predictive nomogram was established. The discrimination, calibration, and clinical utility of the nomogram were based on receiver operating characteristic curve (AUC), concordance index (C-index), calibration curve, and decision curve analysis, respectively. RESULTS: Overall, 18 (3.04%) cases of cut-out occurred. Independent predictors according to the multivariate analysis were body mass index (BMI), poor-to-acceptable quality of reduction, PFNA blade position, and tip-apex distance (TAD). AUC of the nomogram was 0.849, and C-index was 0.849 (95% CI [0.844-0.854]). Bootstrapping yielded a corrected C-index of 0.849. The calibration and decision curves indicated good agreement and clinical benefit of the nomogram. CONCLUSION: A reliable predictive nomogram was developed for cut-out of the PFNA in intertrochanteric fractures, based on BMI, quality of reduction, blade position, and TAD.

Is new always better: comparison of the femoral neck system and the dynamic hip screw in the treatment of femoral neck fractures.

BACKGROUND: Hip fractures in the elderly population are common and the number of patients is rising. For young and geriatric patients with undisplaced fractures osteosynthesis is the primary type of treatment. The dynamic hip screw (DHS) is around for many years and proved its value especially in displaced fractures. Since 2018 the femoral neck system (FNS) is available as an alternative showing promising biomechanical results. The aim of this study is to evaluate clinical results of the FNS and compare it to the DHS. MATERIALS AND METHODS: Patients older than 18 years with Garden I-IV fractures that were treated with osteosynthesis in a level 1 trauma center were included in the study. Between January 2015 and March 2021, all patients treated with FNS (1-hole plate, DePuy-Synthes, Zuchwil, Switzerland) or DHS (2-hole plate, DePuy-Synthes, Zuchwil, Switzerland) for proximal femur fractures were included in the study. Closed reduction was achieved using a traction table. All operations were carried out by experienced orthopedic trauma surgeons. Primary outcome measures were rate of implant failure (cut out) and surgical complications (hematoma, infection). Secondary outcome measures were Hb-difference, length of hospital stay and mortality. RESULTS: Overall, 221 patients were included in the study. 113 were treated with FNS, 108 with DHS. Mean age was 69 ± 14 years. There were 17.2% Garden I, 47.5% Garden II, 26.7% Garden III and 8.6% Garden IV fractures. No difference between the groups for age, body mass index (BMI), Charlson comorbidity index (CCI), time to surgery, Pauwels and Garden classification, rate of optimal blade position or tip apex distance was found. FNS showed lower pre- to postoperative Hb-difference (1.4 ± 1.1 g/l vs. 2.1 ± 1.4 g/l; p < 0.05), shorter operating time (36.3 ± 11.6 min vs. 54.7 ± 17.4 min; p < 0.05) and hospital stay (8.8 ± 4.3 d vs. 11.2 ± 6.8 d; p < 0.05). Surgical complications (FNS 13.3% vs. DHS 18.4%, p > 0.05), rate of cut out (FNS 12.4% vs. DHS 10.2%, p > 0.05) and mortality (FNS 3.5%; DHS 0.9%; p > 0.05) showed no difference between the groups. Logistic regression showed that poor blade position was the only significant predictor for cut out and increased the risk by factor 7. Implant related infection (n = 3) and hematoma/seroma (n = 6) that needed revision was only seen in DHS group. CONCLUSION: FNS proved to be as reliable as DHS in all patients with hip fractures. Not the type of implant but blade positioning is still key to prevent implant failure. Still due to minimal invasive approach implant related infections and postoperative hematomas might have been prevented using the FNS.

Effect of cut-out rescan procedures on the accuracy of an intraoral scanner used for digitizing an ear model: An in vitro study.

PURPOSE: The purpose of this study was to evaluate the impact of the rescanning of mesh holes of different diameters on the accuracy of an intraoral scanner (IOS) used to digitize an ear model. MATERIALS AND METHODS: An ear model was digitized using an intraoral scanner (Medit i500) to obtain a reference mesh. A baseline experimental scan was created by editing a duplicate of the reference mesh using the cut-out tool of the IOS software. Three equal groups were created based on the diameter of the cut-out areas: 2 mm (G1), 5 mm (G2), and 8 mm (G3) (n = 15). The cut-out areas were rescanned and a total of 45 digital files were exported. The discrepancy between the reference and the experimental digital scans was measured using the root mean square calculation (RMS). The data were analyzed by a Kruskal-Wallis test followed by a post hoc Dunn's test with Bonferroni correction. RESULTS: The trueness values ranged from 19.53 to 27.13 µm. There were significant differences in the RMS error values among the groups tested (p < 0.001) and post hoc multiple comparisons showed significant differences between the G1 and G2 groups (p = 0.04), G1 and G3 groups (p < 0.001), and G2 and G3 groups (p = 0.004). Overall, the precision values ranged from 4.93 to 7.73 µm and significant differences in the RMS values were only found between the G1 and G2 groups (p = 0.014). CONCLUSIONS: Mesh hole rescanning affected the scanning accuracy (trueness and precision) of the IOS tested. The larger the diameter of the mesh holes, the less the trueness of the IOS tested. The precision values seemed to be less affected compared with the trueness by the cut-out and rescanning procedures.

Risk factors for cut-outs in geriatric intertrochanteric fractures with cephalomedullary nailing after obtaining acceptable reduction: a case-control study.

BACKGROUND: It is irresponsible if we disregard reduction quality to talk about cut-outs in intertrochanteric fractures (ITF) with internal fixation. The aim of this study is to analyze the risk-factors for cut-outs in geriatric ITF with cephalomedullary nailing after obtaining acceptable reduction. METHODS: In order to investigate the risk-factors for cut-outs in geriatric ITF after obtaining acceptable reduction, we retrospectively reviewed 367 patients who underwent cephalomedullary nail for ITF in our department between September 2016 and December 2021. Potential variables including demographic data and radiological parameters (namely the fracture type, Singh index, lateral wall fracture, cephalic nail position, Parker's ratio index, tip-apex-distance (TAD), and calcar-referenced TAD (CalTAD)) were collected. Logistic regression analysis was performed to identify the significant risk factors for cut-outs. RESULTS: One hundred twenty-one patients were suitable for this study. Of the 121 cases, nine cases (7.4%) were observed with cut-out or pending cut-out. We found that Age (adjusted odds ratio (OR) 1.158, 95% confidence interval (CI) 1.016 to 1.318, p = 0.028), lateral wall fracture (adjusted OR 11.07, 95%CI 1.790 to 68.380, p = 0.01), and CalTAD (adjusted OR 1.277, 95%CI 1.005 to 1.622, p = 0.045) were independent risk-factors for cut-outs. CONCLUSIONS: Age, lateral wall fracture and CalTAD are independent risk-factors for cut-outs in geriatric ITF with cephalomedullary nailing after obtaining acceptable reduction. In order to avoid cut-outs, an optimal CalTAD is necessary even obtaining acceptable reduction, especially in the over-aged patients with lateral wall fracture.

Cut-out risk factor analysis after intramedullary nailing for the treatment of extracapsular fractures of the proximal femur: a retrospective study.

BACKGROUNDS: The basic method of surgical treatment for extracapsular hip fractures (ECFs), including intertrochanteric fracture and basicervical fracture (BCF), is osteosynthesis. Intramedullary nails are among the most commonly used fixation devices for these fractures. Our study aimed to report the clinical outcomes of ECF treatment with two different nail devices and to analyze the risk factors associated with screw cut-out. METHODS: We retrospectively reviewed the medical records of 273 patients (300 cases) from a single institution who underwent surgical treatment for ECF between January 2013 and October 2018. Overall, 138 patients were eligible for the study and were divided into two groups according to the osteosynthesis device used. We evaluated the clinical outcomes of fracture surgery and performed univariate and multivariate regression analyses to identify risk factors associated with screw cut-out in each group. RESULTS: We used proximal femoral nails (group 1) to treat 83 patients and cephalomedullary nails (group 2) to treat 55 patients. Nine cut-outs (group 1, 6 cases; group 2, 3 cases) occurred during follow-up. The patients' high body mass index (BMI) (p = 0.019), BCFs (p = 0.007), non-extramedullary reduction in the anteroposterior and lateral planes (p = 0.032 and p = 0.043, respectively), and anti-rotation screw pull-outs (p = 0.041) showed a positive correlation to screw cut-out in the univariate analysis of group 1. In group 2, only BCFs was positively correlated (p = 0.020). In the multivariate analysis of group 1, the patients' BMIs (p = 0.024) and BCFs (p = 0.024) showed a positive correlation with cut-out. Meanwhile, the multivariate analysis of group 2 did not identify any factors associated with cut-out. CONCLUSIONS: The cut-out risk was significantly higher in the BCF cases, regardless of the nail design used. Considerable attention should be paid to treating such unstable fractures. We expect that new-generation nails using a helical blade, or interlocking derotation and interlocking screws may improve surgical outcomes.

A Method of Optimizing Characteristic Impedance Compensation Using Cut-Outs in High-Density PCB Designs.

The modern era of technology contains a myriad of high-speed standards and proprietary serial digital protocols, which evolve alongside the microwave and RF realm. The increasing data rate push the requirements for hardware design, including modern printed circuit boards (PCB). One of these requirements for modern high-speed PCB interfaces are a homogenous track impedance all the way from the source to the load. Even though some high-speed interfaces don't require any external components embedded into the interconnects, there are others which require either passive or active components-or both. Usually, component package land-pads are of fixed size, thus, if not addressed, they create discontinuities and degrade the transmitted signal. To solve this problem, impedance compensation techniques such as reference plane cut-out are employed for multiple case studies covering this topic. This paper presents an original method of finding the optimal cut-out size for the maximum characteristic impedance compensation in high-density multilayer PCB designs, which has been verified via theoretical estimation, computer simulation, and practical measurement results. Track-to-discontinuity ratios of 1:1.75, 1:2.5, and 1:5.0 were selected in order to resemble most practical design scenarios on a 6-layer standard thickness PCB. The measurements and simulations revealed that the compensated impedance saturation occurs at (150-250%) cut-out widths for a 50 Ω microstrip.

Use of a Trochanteric Fixation Nail-Advanced (TFNA) with cement augmentation for treatment of trochanteric fractures in patients greater than sixty five years of age.

PURPOSE: Intramedullary nailing is the standard treatment of trochanteric fractures. Mechanical failure such as cut-out and cut-through are associated with high rates of revision surgery, functional impairment, and mortality. The aim of the study was to evaluate the rate of mechanical failure of the cement augmented screws of Trochanteric Fixation Nail-Advanced (TFNA) nails. PATIENTS AND METHODS: A descriptive, retrospective, multi-operator, single-centre study was performed at our level 1 trauma centre between June 2019 and June 2020. Patients were included if they were > 65 years of age, presented with a trochanteric fracture treated with an augmented TFNA nail with 6 months of follow-up. The primary outcome was fixation failure rate (cut-out or cut-through) at three and six post-operative months. Secondary endpoints were intra-operative data, clinical scores, and radiographic analysis. RESULTS: Forty-five patients (38 women and 7 men) were analysed. The mean age was 82.84 years (65-102, 9.50). There were no instances of mechanical failure in our series, after either three or six months of follow-up. No patient exhibited cut-out or cut-through. The mean amount of cement injected was 4.72 mL (3-6; 1.05). The mean length of surgery was 37.59 min (25-55; 6.48), and the mean intra-operative radiation exposure was 91.47 cGycm2 (25.04-201.81; 51.40) for a mean duration of 43.11 s (17-86; 16.81). The mean duration of hospitalisation was 6.38 days (2-11; 2.27). CONCLUSIONS: Our clinical results suggest that cement-augmented TFNA screws can be successfully used in the management of trochanteric fractures in patients > 65 years of age.

Salvage hip replacement after cut-out failure of cephalomedullary nail fixation for proximal femur fractures: a case series describing the technique and results.

BACKGROUND: Cut-out failure following proximal femoral fracture fixation is a compromising complication warranting surgical treatment. We describe 24 patients with cut-out failure after cephalomedullary nail fixation managed with salvage hip replacement. METHODS: Twenty-four consecutive patients who had sustained a proximal femoral fracture from December 2009 to December 2019, were managed with cephalomedullary nail fixation and experienced a cut-out failure were reviewed retrospectively. Data on demographics, comorbidities, injury characteristics, treatment, and post-operative course were analysed. RESULTS: Among 2802 proximal femoral fractures assessed, 28 fixations failed due to cut-out, with 24/28 patients subsequently undergoing salvage hip replacement. Intertrochanteric fractures (66.7%) managed with short nails predominated (79.2%). The median tip-to-apex distance (TAD) was 19 mm, but only two fractures had a good quality of reduction. Inverse correlations were identified between patient age and the time from fixation to cut-out (r = - 0.57; p = 0.02), and between the time of nailing to failure among patients with a greater TAD (r = - 0.43; p = 0.04). Most patients were managed via cemented hemiarthroplasty (66.7%). Surgical time was longer for total hip replacements (175.4 vs. 136.8 min; p < 0.01), but no bleeding or blood transfusion requirement differences were found. Two patients had orthopaedic complications, and three patients died within the first follow-up year. CONCLUSION: In our series, 1% of the proximal femoral fractures managed with a cephalomedullary nail failed due to cut-out. Salvage hip replacement appeared to be a relatively safe and reliable procedure for managing this challenging complication in patients who typically are elderly and physically frail.

Tip-neck distance ratio as a novel predictor for failure in cephalomedullary nailing of unstable trochanteric fractures (UTF).

OBJECTIVES: Intertrochanteric femur fractures (ITFF) are frequently fixed with proximal femoral nailing (PFN), and a common cause of fixation failure is cut-out of the lag screws. In the literature, many factors have been defined to determine the failure risk, including the tip-apex distance (TAD), calcar-referenced tip-apex distance (CalTAD), the Cleveland zone and Parker's ratio. In this study, a novel technique is described which favors infero-posterior placement of the lag screw and predicts failure risk for PFN. The purpose of this study was to evaluate the tip-neck distance ratio as a factor for the prediction of cut-out after PFN of ITFF. MATERIALS AND METHODS: A retrospective evaluation was made of the data of 125 patients applied with PFN for ITFF between October 2016 and September 2019. The occurrence of mechanical complications was analyzed in relation to age, gender, fracture side, American Society of Anaesthesiologists classification, fracture classification, reduction quality, bone quality, Cleveland zone, Parker's ratio, TAD, CalTAD and the TNDR. RESULTS: A total of 125 patients, including 16 with mechanical complications, were suitable for full analysis. In the univariate analysis, reduction quality (p = 0.003), the TAD (p = 0.048) and the TNDR (p = 0.030) were statistically associated with mechanical complications (p < 0.05). In the multivariate analysis, good quality of reduction reduced risk of mechanical failure (p = 0.011) and the TNDR (p < 0.001) indicated that these were two independent factors affecting mechanical complications. CONCLUSION: The results of this study provide clinical evidence that the TNDR is a predictor for cut-out risk. Placement of the lag screw posterior and inferior reduces the risk of mechanical complications. LEVEL OF EVIDENCE: Level 3.

Conversion total hip arthroplasty for early failure following unstable intertrochanteric hip fracture: what can patients expect?

PURPOSE: To report surgical outcomes in patients treated with conversion total hip arthroplasty (CTHA) for early failure of cephalomedullary nails (CMNs). METHODS: A retrospective review was conducted of CTHA for treatment of failed CMN within 1 year of initial surgery for intertrochanteric (IT) hip fractures. The cohort was matched 1:5 to patients who underwent elective primary THA (PTHA). Patient demographics, mechanism of CMN failure, surgical outcomes, and complication rates were assessed. RESULTS: 22 patients met criteria with a mean time to failure of 145 days. Modes of failure included: lag screw cut-out with superior migration (9, 40.9%), or medialization (8, 36.4%), and aseptic nonunion with implant failure (2, 9.0%) and without implant failure (3, 13.6%). Fourteen of the patients (63.6%) had acetabular-sided damage secondary to lag screw penetration, all in the screw cut-out groups. Patient demographics were similar between cohorts. Compared to PTHA, CTHA patients had increased operative time, blood loss, LOS, and readmission rates. After IMN failure, the operative leg was shorter than the contralateral leg in all cases. CTHA restored leg lengths to < = 10 mm in 15 (68.1%) of patients, with an average leg length discrepancy after CTHA of 6.7 mm. CTHA patients had increased rates of overall surgical complications and medical complications, specifically anemia (all p < 0.01). Tranexamic acid was used less often in the CTHA group (p < 0.01). Rate of periprosthetic joint infection (PJI), dislocation, and revision were all higher in the CTHA, though did not reach statistical significance. CONCLUSION: The majority (77.3%) of CMN implant failure for nonunion within 1 year was due to screw cut-out. CTHA is a salvage option for early failed IT hip fracture repair, but expected surgical outcomes are more similar to revision THA than primary THA, with increased risk of readmission, longer surgery and LOS, increased blood loss, and higher complication rates. LEVEL OF EVIDENCE: III, Retrospective comparative study.

Comparison of Helical Blade Systems for Osteoporotic Intertrochanteric Fractures Using Biomechanical Analysis and Clinical Assessments.

Background and Objectives: This study aimed to compare the biomechanical properties and outcomes of osteoporotic intertrochanteric fractures treated with two different helical blade systems, the trochanteric fixation nail-advanced (TFNA) and proximal femoral nail antirotation II (PFNA), to evaluate the efficacy and safety of the newly introduced TFNA system. Materials and Methods: A biomechanical comparison of the two helical blades was performed using uniaxial compression tests on polyurethane foam blocks of different densities. The peak resistance (PR) and accumulated resistance (AR) were measured during the 20 mm advancement through the test block. For clinical comparison, 63 osteoporotic intertrochanteric fractures treated with TFNA were identified and compared with the same number of fractures treated with PFNA using propensity score matching. Ambulatory status, medial migration, lateral sliding, fixation failure, and patient-reported outcomes were compared between the two groups over a minimum of 1 year's follow up. Results: The uniaxial compression test showed that a slightly, but significantly lower resistance was required to advance the TFNA through the test block compared with the PFNA (20 PCF, p = 0.017 and p = 0.026; 30 PCF, p = 0.007 and p = 0.001 for PR and AR, respectively). Clinically, the two groups showed no significant differences in post-operative ambulatory status and patient-reported outcomes. However, in TFNA groups, significantly more medial migration (TFNA, 0.75 mm; PFNA, 0.40 mm; p = 0.0028) and also, lateral sliding was noted (TFNA, 3.99 mm; PFNA, 1.80 mm; p = 0.004). Surgical failure occurred in four and two fractures treated with the TFNA and PFNA, respectively. Conclusions: The results of our study suggest that the newly introduced TFNA provides clinical outcomes comparable with those of the PFNA. However, inferior resistance to medial migration in the TFNA raises concerns regarding potential fixation failures.

No difference between lag screw and helical blade for cephalomedullary nail cut-out a systematic review and meta-analysis.

INTRODUCTION: Cephalomedullary nail (CMN) cut-out is a severe complication of treatment of intertrochanteric femur fractures. This study aimed to identify modifiable risk factors predictive of implant cut-out including: CMN proximal fixation type (lag screw vs. helical blade), tip-apex distance (TAD), reduction quality, nail length, screw location, and surgeon fellowship training. METHODS: A systematic review of the published literature was conducted on Pubmed/MEDLINE and Cochrane Library databases for English language papers (January 1st, 1985-May 10th, 2020), with 21 studies meeting inclusion/exclusion criteria. Studies providing quantitative data comparing factors affecting CMN nail cut-out were included, including fixation type (lag screw vs. helical blade), tip-apex distance (TAD), reduction quality, nail length, and screw location. Twelve studies were included and graded by MINOR and Newcastle-Ottawa Scale to identify potential biases. Meta-analysis and pooled analysis were conducted when possible with forest plots to summarize odds ratios (OR) and associated 95% confidence interval (CI). RESULTS: There was no difference in implant cut-out rate between lag screws (n = 745) versus helical blade (n = 371) (OR: 1.03; 95% CI: 0.25-4.23). Pooled data analysis revealed TAD > 25 mm (n = 310) was associated with higher odds of increased cut-out rate relative to TAD < 25 mm (n = 730) (OR: 3.72; 95% CI: 2.06-6.72). CONCLUSION: Our review suggests that cephalomedullary implant type (lag screw vs. helical blade) is not a risk factor for implant cut-out. Consistent with the previous literature, increased tip-apex distance > 25 mm is a reliable predictor of implant cut-out risk. Suboptimal screw location and poor reduction quality are associated with increased risk of screw cut-out. LEVEL OF EVIDENCE: Level III.

Risk factors for mechanical failure of intertrochanteric fractures after fixation with proximal femoral nail antirotation (PFNA II): a study in a Southeast Asian population.

INTRODUCTION: Intertrochanteric hip fractures pose a significant health problem. The proximal femur nail anti-rotation (PFNA IIDePuySynthes) is the most commonly used implant for intramedullary nailing of unstable intertrochanteric fractures at our institution. We aim to identify the risk factors predisposing to mechanical failure of intertrochanteric hip fractures fixation with PFNAII in our Southeast Asian population. MATERIALS AND METHODS: We retrospectively reviewed 295 consecutive patients who underwent PFNA fixation for intertrochanteric fractures of the proximal femur between January 2014 and June 2018 at our institution. Exclusion criteria included a follow-up period of less than 4 months and patients with polytrauma. 204 patients were eligible for analysis, of which 22 had mechanical failure of PFNAII. We compared these patients with respect to their demographics, medical co-morbidities, quality of reduction according to the Baumgartner scale, calcar restoration, blade position according to Cleveland Zones, the stability of fracture according to OTA/AO classification, neck-shaft-angle, tip-apex distance, as well as neck of femur bone mineral density T-score. Patients were followed up for a minimum of 4 months and until fracture union or complication had occurred. Logistic regression analysis was performed to determine the odds ratio for mechanical failure for selected variables. RESULTS: Good quality of reduction reduced risk of mechanical failure whilst posterior blade position in lateral hip X-ray predicted it, with odds ratios of 0.147 (95% confidence interval, 0.030-0.733; p = 0.019) and12.12 (95% confidence interval, 1.583-92.825; p = 0.016) respectively. On univariate analysis, the mechanical failure group were older, had poorer calcar restoration, more unstable fracture patterns, more varus neck-shaft angle, and trochanteric starting points that were lateral to or on the tip of the greater trochanter. However, these were not significant in multivariate analysis. Tip apex distance, the severity of osteoporosis, presence of diabetes, chronic kidney disease and serum vitamin D levels were not significant predictors of failure. CONCLUSIONS: To avoid mechanical failure, one should aim to achieve a good quality of reduction and centre blade position on lateral hip X-ray. Tip apex distance did not predict mechanical failure in our study.

Long-term outcomes of distal locking in extracapsular fractures treated with trochanteric Gamma3 nails.

BACKGROUND: Few publications have assessed long-term results of distal locking of short endomedullary nails for extracapsular hip fracture. Virtually all of them focus on immediate differences. Criteria for the use of static or dynamic locking are unclear in most nailing systems, and use is advised in unstable fracture patterns or with risk of bell-clapper effect, but often influenced by the "orthopaedic school". MATERIALS AND METHODS: This is a historical cohort study on patients diagnosed and operated in 2014 and followed up until endpoint, considered as consolidation or major complication, plus evaluation of overall long-term survival. They were categorised as static distal locking (ST) or dynamic distal locking (DN). Both are comparable, except for all stable pre-operative classifications, Fracture Mobility Score (FMS) at discharge, and immediate post-operative loading, all of which were in favour of DN. RESULTS: Consolidation took place in > 95% of patients, with a non-statistically significant delay trend in ST. Less than 6% in both ST and DN had major complications, with no differences. Most cases suffered early cut-out. Significant fracture collapse was the most frequent minor complication. There were more statistically significant minor and total complications in ST. Infection, without differences, can precede cut-out. Lateral thigh pain was similar and could be related to back-out. In DN, 21.1% of cases were truly dynamised. We did not find differences in mobility or in long-term survival. CONCLUSIONS: Any type of distal locking seems to be safe for consolidation, despite a slightly longer consolidation time in static locking. Early cut-out was the main complication, while others were very infrequent, which is an advantage over helical blade devices. There was a higher rate of minor and overall mechanical complications in ST, but infection and lateral thigh pain were similar. Most non-traumatic mechanical complications occurred around 5-6 weeks. About one in five of the DN truly dynamised, with all cases occurring before 8 weeks. Mobility until endpoint and overall long-term survival were not influenced by the locking mode used. LEVEL OF EVIDENCE: Therapeutic study, level 2b.

Finite Element-Predicted Effects of Screw Configuration in Proximal Humerus Fracture Fixation.

Internal fixation with the use of locking plates is the standard surgical treatment for proximal humerus fractures, one of the most common fractures in the elderly. Screw cut-out through weak cancellous bone of the humeral head, which ultimately results in collapse of the fixed fracture, is the leading cause of failure and revision surgery. In an attempt to address this problem, surgeons often attach the plate with as many locking screws as possible into the proximal fragment. It is not thoroughly understood which screws and screw combinations play the most critical roles in fixation stability. This study conducted a detailed finite element analysis to evaluate critical parameters associated with screw cut-out failure. Several clinically relevant screw configurations and fracture gap sizes were modeled. Findings demonstrate that in perfectly reduced fracture cases, variation of the screw configurations had minor influence on mechanical stability of the fixation. The effects of screw configurations became substantial with the existence of a fracture gap. Interestingly, the use of a single anterior calcar screw was as effective as utilizing two screws to support the calcar. On the other hand, the variation in calcar screw configuration had minor influence on the fixation stability when all the proximal screws (A-D level) were filled. This study evaluates different screw configurations to further understand the influence of combined screw configurations and the individual screws on the fixation stability. Findings from this study may help decrease the risk for screw cut-out with proximal humerus varus collapse and the associated economic costs.