Torsional stability of fixation methods in basicervical femoral neck fractures: a biomechanical study.

BACKGROUND: Basicervical femoral neck fracture is a rare proximal femur fracture with a high implant failure rate. Biomechanical comparisons between cephalomedullary nails (CMNs) and dynamic hip screws (DHSs) under torsion loading are lacking. This study compared the biomechanical performance of three fixations for basicervical femoral neck fractures under torsion load during early ambulation. METHODS: The biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability. RESULTS: The EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1-5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs. CONCLUSIONS: Titanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout.

Comparative study of mechanical performance of various fixation constructs in multifragmentary distal humeral shaft fracture: a finite element analysis.

BACKGROUND: There has been no scientific mechanical assessment demonstrating the optimal fixation technique in multifragmentary fractures of the distal humeral shaft. The purpose of the present study was to compare the biomechanical performance of 5 fixation constructs as used in minimally invasive plating osteosynthesis (MIPO) for distal humeral shaft fractures. METHODS: Three-dimensional (3D) humerus model with 20 mm distal humeral shaft fracture gap simulating multifragmentary fracture was created from computed tomography data and virtually fixed by 5 fixation techniques as MIPO, i.e., anterior narrow dynamic compression plate (DCP), anterior narrow locking compression plate (LCP), anterior reversed proximal humeral internal locking system (R-PHILOS), extra-articular distal humerus locking compression plate (LCP-EADH), and anteromedial LCP. All constructs were biomechanically tested under 6 loading conditions by means of finite element analysis, i.e., 250-N axial compression, 7.5-N m internal rotation, 7.5-N m external rotation, 10-N m posterior bending, 10-N m valgus rotation, and 10-N m varus rotation. In addition, A 3D model of each construct was fabricated as 3D printed models. Fixations were applied to the 3D printing model which were later mechanically tested to validate the FE results. RESULTS: EQV stress exhibited on anterior narrow LCP and anterior R-PHILOS were comparable which were lower than other constructs under axial compression and valgus-varus bending. Anterior R-PHILOS produced lower EQV stress than other constructs under internal-external rotation and posterior bending. On the whole, R-PHILOS demonstrated a comparable fracture displacement to those LCP with anterior or anteromedial approaches, that achieved the lowest displacement values. In addition, the experimental mechanical test values shared a correlation with the FE model results. CONCLUSION: Overall, the anterior R-PHILOS was considered as a potential candidate for multifragmentary distal humeral shaft fractures. It demonstrated efficacious biomechanical performance in terms of implant stress and distal fragment displacement.

Nonvascularized fibular graft with locking screw fixation for metaphyseal bone loss of distal femur: biomechanical assessment validated by a clinical case series.

BACKGROUND: The optimal modality to surgically treat significant bone loss of distal femur remains inconclusive. The objectives of the present study were to assess the mechanical performance of nonvascularized fibular graft (NVFG) with locking screw fixation in distal femur fixation construct by finite element analysis and to retrospectively describe the outcomes of the present technique in clinical cases. METHODS: Four constructs which the fractured femur was stabilized by LCP-DF alone, dual plating, LCP-DF combined with NVFG, and LCP-DF combined with NVFG (LCP-DF-NVFG-S) with locking screw were assessed the biomechanical performance under physiological loads. For the clinical case series, 12 patients with open intercondylar fracture with metaphyseal bone loss of distal femur were operated by LCP-DF-NVFG-S. The collected data included fracture consolidation, length of NVFG, perioperative complications and objective clinical results. RESULTS: LCP-DF-NVFG-S demonstrated lower implant equivalent von Mises stress (EQV) stress and better fracture stability than other constructs. A locking screw presented its essence in maintaining the NVFG in the required position and subsequently enhancing the fracture stability. In regard to the clinical series, all fractures were consolidated with an average duration of 27.8 weeks (range 20-32). An average NVFG length was 7.8 cm (range 6-12). No perioperative complication was demonstrated. By the Knee Society score, 1 was considered to be excellent, 9 to be good and 2 to be poor. CONCLUSION: Based on the results of mechanical assessment and case series, LCP-DF-NVFG-S can be an effective technique in the management of metaphyseal bone loss of distal femur.

Exploring the osteoporosis treatment gap after fragility hip fracture at a Tertiary University Medical Center in Thailand.

BACKGROUND: (1) To evaluate the prescription rate of anti-osteoporosis medication, and (2) to identify factors associated with patients not receiving anti-osteoporosis medication or, when prescribed, not persisting with medication 1 year after hip fracture treatment. METHODS: We retrospectively reviewed the medical records of all fragility hip fracture patients admitted to the orthopedic unit of the Faculty of Medicine Siriraj Hospital, Mahidol University, between July 1, 2016, and December 31, 2019. We identified patients who did not receive anti-osteoporosis medication both 6 months and 1 year after fracture treatment. Patients who did not receive the medication 1 year after their treatment were enrolled and interviewed using a no-treatment questionnaire. RESULTS: In total, 530 patients with fragility hip fractures were eligible (mean age, 79.0 years), and most (74.5%) were women. Only 148 patients (31.6%) received anti-osteoporosis medication 1 year after hip fracture. Logistic regression analysis identified predictors for not receiving the medication: male sex (OR 1.8; 95% CI 1.1-3.0), Charlson comorbidity index score ≥ 5 (OR 1.5; 95% CI 1.0-2.3), and secondary school education or below (OR 2.0; 95% CI 1.2-3.3). The main reason for not receiving the medication was that healthcare providers neither discussed nor initiated pharmacological treatment for osteoporosis (48.2%). When the medication was prescribed, non-persistence primarily stemmed from transportation difficulties that resulted in patients missing follow-ups (50.0%). CONCLUSIONS: Improved physician attitudes toward anti-osteoporosis medications might enhance the treatment rate. Developing a follow-up team and facilitating access to medications (eg, courier delivery to patients) would promote therapy compliance. TRIAL REGISTRATIONS: The protocol for the first phase and second phase was approved by the Siriraj Institutional Review Board of the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand (COA no. Si 180/2021) and for the second phase, patients-informed consent forms used in the cross-sectional component were approved by the Siriraj Institutional Review Board of the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand (COA no. Si 180/2021). The research was registered with the Thai Clinical Trials Registry (TCTR number: 20210824002). The study was conducted in accordance with the Declaration of Helsinki. Each patient (or a relative/caregiver) provided informed consent in writing or by telephone to participate in this second study phase.

Dual plating for fixation failure of the distal femur: Finite element analysis and a clinical series.

BACKGROUND: The optimal technique for managing distal femur fixation failure remains inconclusive. The author studied the efficacy of a combined proximal humerus locking compression plate (LCP-PH) and 3.5 mm reconstruction plate (LCP-RP) by finite element (FE) analysis and retrospectively described the clinical outcomes of the present technique in such difficult circumstances. METHODS: Biomechanical study setting included FE models of the distal femur with remaining holes from previous distal femur LCP (LCP-DF) fixation stabilized with three different constructs i.e., LCP-DF alone, LCP-DF-and-LCP-RP, as well as LCP-PH-and-LCP-RP. All settings were analyzed by using FE under physiological loads. Regarding the clinical series, the outcomes of 8 LCP-DF fixation failures operated on by the present technique were retrospectively reviewed. RESULTS: High Implant stress of 911.2 MPa and elastic strain at fracture site of 200.8 µÉ› were found when stabilized with LCP-DF. The constructs of LCP-DF-and-LCP-RP, and LCP-PH-and-LCP-RP presented lower implant stress compared to LCP-DF, 511.5, and 617.5 MPa, respectively. The elastic strain of both dual plating constructs was also 4-5 times lower than LCP-DF and differed from each other by approximately 10 µÉ›. Regarding the clinical series, bony consolidation was achieved in all cases with a mean duration of 28.5 weeks (range 24-36). An average ROM of the affected knee was 115° (range 105-140). Regarding the KSS, 1 was determined to be excellent and 7 to be good. CONCLUSION: By the biomechanical analysis and the clinical results, the construct of LCP-PH-and-LCP-RP could be an effective technique for revision surgery of LCP-DF fixation failure.

Comparative biomechanical performance of two configurations of screw constructs and types used to stabilize different sites of unstable Pauwels type II femoral neck fractures: A finite element analysis.

BACKGROUND: A smaller dimension of the femoral neck in the Asian population may have difficulty placing inverted triangle multiple screws configuration for treatment. Posterior triangle configuration, which is suitable in limited space of the femoral neck, is a promising alternative treatment approach. This study aimed to investigate the biomechanical performance of inverted and posterior triangles of multiple screws fixation configuration for both cannulated and standard solid-core screws in stabilizing Pauwels type II femoral neck fracture sub-capital, mid-cervical, and basilar regions using Finite Element (FE) method. METHODS: A 3D femur model was created for Pauwels type II femoral neck fractures. The fracture sites were in the mid-cervical, sub-capital, and basilar regions, with a spacing of 7 mm between adjacent fracture lines. Both cannulated and solid-core screws were configured in the inverted and posterior triangle patterns. The applied physiological loads to the FE models included muscle and hip contact forces. Equivalent von Mises (EQV) stresses were used to monitor fixation strength whereas elastic strain of each configuration indicated the degree of stability of a fracture site. RESULTS: EQV stress on the screws for posterior and inverted triangle configuration ranged from 212.1 to 290.2 MPa, and 224.4-314.8 MPa, respectively. The EQV stress the posterior triangle configuration was lower than the inverted triangle configuration by 5.5-10.8%. The stress exhibited on the screw was greatest when the fracture site was at basilar regions, 1.1-1.3 times greater than fracture in sub-capital region. Elastic strain at fractures retained by cannulated screw was greater than solid-core screw with maximum difference of 68 microstrains. Cannulated screw provided less stability than the solid-core screw. CONCLUSIONS: The screws used in the posterior triangle configuration exhibits lower screw stress in all fracture regions of the femoral neck. The solid-core screw shows superior biomechanical properties compared with cannulated screw with lower EQV stress and better fracture stability. Posterior triangle configuration is considered an alternative treatment of choice for the patient with a small dimension of the femoral neck.

Development and internal validation of a machine-learning-developed model for predicting 1-year mortality after fragility hip fracture.

BACKGROUND: Fragility hip fracture increases morbidity and mortality in older adult patients, especially within the first year. Identification of patients at high risk of death facilitates modification of associated perioperative factors that can reduce mortality. Various machine learning algorithms have been developed and are widely used in healthcare research, particularly for mortality prediction. This study aimed to develop and internally validate 7 machine learning models to predict 1-year mortality after fragility hip fracture. METHODS: This retrospective study included patients with fragility hip fractures from a single center (Siriraj Hospital, Bangkok, Thailand) from July 2016 to October 2018. A total of 492 patients were enrolled. They were randomly categorized into a training group (344 cases, 70%) or a testing group (148 cases, 30%). Various machine learning techniques were used: the Gradient Boosting Classifier (GB), Random Forests Classifier (RF), Artificial Neural Network Classifier (ANN), Logistic Regression Classifier (LR), Naive Bayes Classifier (NB), Support Vector Machine Classifier (SVM), and K-Nearest Neighbors Classifier (KNN). All models were internally validated by evaluating their performance and the area under a receiver operating characteristic curve (AUC). RESULTS: For the testing dataset, the accuracies were GB model = 0.93, RF model = 0.95, ANN model = 0.94, LR model = 0.91, NB model = 0.89, SVM model = 0.90, and KNN model = 0.90. All models achieved high AUCs that ranged between 0.81 and 0.99. The RF model also provided a negative predictive value of 0.96, a positive predictive value of 0.93, a specificity of 0.99, and a sensitivity of 0.68. CONCLUSIONS: Our machine learning approach facilitated the successful development of an accurate model to predict 1-year mortality after fragility hip fracture. Several machine learning algorithms (eg, Gradient Boosting and Random Forest) had the potential to provide high predictive performance based on the clinical parameters of each patient. The web application is available at www.hipprediction.com . External validation in a larger group of patients or in different hospital settings is warranted to evaluate the clinical utility of this tool. TRIAL REGISTRATION: Thai Clinical Trials Registry (22 February 2021; reg. no. TCTR20210222003 ).

Single lag screw and reverse distal femur locking compression plate for concurrent cervicotrochanteric and shaft fractures of the femur: biomechanical study validated with a clinical series.

BACKGROUND: The optimal surgical management of concurrent cervicotrochanteric and shaft fractures of the femur has not been consensual. The authors investigated the reliability of combined single lag screw and reverse distal femur locking compression plate (LCP-DF) by finite element (FE) study and retrospectively described the present technique for these dual fractures. METHOD: Intact femurs were derived from CT data, and the implant models were created by using CAD software. The fractured femur and implant models were virtually aligned based on the surgical techniques before converting to the FE model. In the FE model, applied boundary conditions included body weight, muscle forces, and constraint of the joints. Regarding clinical series, three patients with these dual fractures of the femur and 2 with cervicotrochanteric fractures with subtrochanteric extension were operated on by the proposed technique. The collected data include operative time, postoperative complications, union times, and clinical outcomes. RESULTS: Equivalent von Mises stress exhibited on dynamic hip screws with an anti-rotational screw was higher than the other techniques, close to the yield stress of the material. Multiple screw fixation produced better stability for transcervical fractures whereas the proposed technique of combined single lag screw and reverse LCP-DF provided better stability for intertrochanteric fractures. No significant difference in cortical bone stress was found between multiple screw construct and the proposed technique. The proposed technique presented a lower risk of secondary fractures, as the strain energy density (SED) in cancellous bone was lower than multiple screw construct. Regarding clinical series, all fractures were united with a mean union time of-16.1 weeks (range 12-20). There were no any postoperative complications. Regarding the Harris score, 1 was determined to be excellent value, and 4 to be good. CONCLUSION: By the FE results, a combination of a single lag screw and reverse LCP-DF is an effective technique for fixation of cervicotrochanteric fractures. Empowered by the clinical results, this proposed technique could be an alternative for concurrent cervicotrochanteric and shaft fractures of the femur especially when either single-system or dual-system devices seem not to be suitable.