Determination of the ideal plate for medial femoral condyle fracture fixation: an anatomical fit and biomechanical study.

BACKGROUND: The aim of this study is to determine the best plate to use as a substitute to fix a medial femoral condyle fracture. MATERIALS AND METHODS: The first part is to measure the best fit between several anatomical plates including the Proximal Tibia Anterolateral Plate (PT AL LCP), the Proximal Tibia Medial Plate (PT M LCP), the Distal Tibia Medial Locking Plate (DT M LCP) and the Proximal Humerus (PHILOS) plate against 28 freshly embalmed cadaveric distal femurs. Measurements such as plate offset and number of screws in the condyle and shaft shall be obtained. The subsequent part is to determine the compressive force at which the plate fails. After creating an iatrogenic medial condyle fracture, the cadavers will be fixed with the two plates with the best anatomical fit and subjected to a compression force using a hydraulic press. RESULTS: The PT AL LCP offered the best anatomical fit whereas the PHILOS plate offered the maximal number of screws inserted. The force required to create 2 mm of fracture displacement between the two is not statistically significant (LCP 889 N, PHILOS 947 N, p = 0.39). The PT AL LCP can withstand a larger fracture displacement than the PHILOS (LCP 24.4 mm, PHILOS 17.4 mm, p = 0.004). DISCUSSION AND CONCLUSION: Both the PT AL LCP and the PHILOS remain good options in fixing a medial femoral condyle fracture. Between the two, we would recommend the PT AL LCP as the slightly superior option.

Clinical outcomes and affecting factors of ipsilateral femoral neck and shaft fractures - Multination, multicenter analysis.

BACKGROUND: This study aimed to evaluate the clinical outcomes of ipsilateral femoral neck and shaft fractures and identify the risk factors associated with missed diagnosis of femoral neck fractures and clinical outcomes of this fracture. METHODS: The ipsilateral femoral neck and shaft fractures from seven centers were retrospectively reviewed. Data on injury mechanism, fracture pattern, and fracture classification; surgical factors including fixation method; and timing of detection of femoral neck fracture were analyzed. The clinical outcomes, complications, and the incidence of avascular necrosis of the femoral head (AVNFH) were reviewed. Risk factors for missed femoral neck fracture and complications were analyzed. RESULTS: In total, 74 patients with an average age of 43.6 years were included. Of the femoral shaft fractures, 56.8% were type A, 21.6% were type B, and 21.6% were type C. Sixteen patients had an open fracture of the femoral shaft. Femoral neck fracture was initially missed in 27% patients and the timing of delayed diagnosis was at an average of 11.1 days after injury. For detecting femoral neck fractures, minimal displacement of the femoral neck fracture was a risk factor, whereas computed tomography (CT) was a protective factor. The incidence of AVNFH was 6.8% at an average of 36.8 months after injury. The AVNFH group had more displaced femoral neck fractures at the time of surgery, but there was no difference in the timing of diagnosis compared to non-AVNFH group. The femoral shaft showed considerable healing problems, with an average union time of 29.7 weeks and a 20.2% nonunion rate. CONCLUSION: Ipsilateral femoral neck and shaft fractures had a high rate of missed diagnosis, especially in minimally displaced fractures; however, CT was a protective factor. AVNFH occurred in 6.8% and was related to femoral neck fracture displacement, but not delayed diagnosis. The femur nonunion rate was high, which warrants attention.

Can a Wireless Full-HD Head Mounted Display System Improve Knee Arthroscopy Performance? - A Randomized Study Using a Knee Simulator.

INTRODUCTION: Our prototype wireless full-HD Augmented Reality Head-Mounted Display (AR-HMD) aims to eliminate surgeon head turning and reduce theater clutter. Learning and performance versus TV Monitors (TVM) is evaluated in simulated knee arthroscopy. METHODS: 19 surgeons and 19 novices were randomized into either the control group (A) or intervention group (B) and tasked to perform 5 simulated loose-body retrieval procedures on a bench-top knee arthroscopy simulator. A cross-over study design was adopted whereby subjects alternated between devices during trials 1-3, deemed the "Unfamiliar" phase, and then used the same device consecutively in trials 4-5, to assess performance in a more "Familiarized" state. Measured outcomes were time-to-completion and incidence of bead drops. RESULTS: In the unfamiliar phase, HMD had 67% longer mean time-to-completion than TVM (194.7 ± 152.6s vs 116.7 ± 78.7s, P < .001). Once familiarized, HMD remained inferior to TVM, with 48% longer completion times (133.8 ± 123.3s vs 90.6 ± 55s, P = .052). Cox regression revealed device type (OR = 0.526, CI 0.391-0.709, P < .001) and number of procedure repetitions (OR = 1.186, CI 1.072-1.311, P = .001) are significantly and independently related to faster time-to-completion. However, experience is not a significant factor (OR = 1.301, CI 0.971-1.741, P = .078). Bead drops were similar between the groups in both unfamiliar (HMD: 27 vs TVM: 22, P = .65) and familiarized phases (HMD: 11 vs TVM: 17, P = .97). CONCLUSION: Arthroscopic procedures continue to be better performed under conventional TVM. However, similar quality levels can be reached by HMD when given more time. Given the theoretical advantages, further research into improving HMD designs is advocated.

Surgeon-designed patient-specific instrumentation improves glenoid component screw placement for reverse total shoulder arthroplasty in a population with small glenoid dimensions.

PURPOSE: Glenoid component loosening is a potential complication of reverse total shoulder arthroplasty (rTSA), occurring in part due to lack of adequate screw purchase in quality scapular bone stock. This study was to determine the efficacy of a surgeon-designed, 3D-printed patient-specific instrumentation (PSI) compared to conventional instrumentation (CI) in achieving longer superior and inferior screw lengths for glenoid component fixation. METHODS: A multi-centre retrospective analysis of patients who underwent rTSA between 2015 and 2020. Lengths of the superior and inferior locking screws inserted for fixation of the glenoid baseplate component were recorded and compared according to whether patients received PSI or CI. Secondary outcomes included operative duration and incidence of complications requiring revision surgery. RESULTS: Seventy-three patients (31 PSI vs. 42 CI) were analysed. Average glenoid diameter was 24.5 mm (SD: 3.1) and 81% of patients had smaller glenoid dimensions compared to the baseplate itself. PSI produced significantly longer superior (44.7 vs. 30.7 mm; P < 0.001) and inferior (43.0 vs. 31 mm; P < 0.001) mean screw lengths, as compared to CI. A greater proportion of maximal screw lengths for the given rTSA construct (48 mm) were observed in the PSI group (71.9% vs. 11.9% superior, 59.4% vs. 11.9% inferior). Operative duration was not statistically significantly different between the PSI and CI groups (150 min vs. 169 min, respectively; P = 0.229). No patients had radiographic loosening of the glenoid component with an average of 2-year follow-up. CONCLUSION: PSI facilitates longer superior and inferior screw placement in the fixation of the glenoid component for rTSA. With sufficient training, PSI can be designed and implemented by surgeons themselves.

Stenotic intercondylar notch is not a risk factor for posterior cruciate ligament rupture: a morphological analyses using magnetic resonance imaging.

PURPOSE: The present study aimed to examine the factors related to the morphological characteristics of the femoral condyle in posterior cruciate ligament rupture in female and male populations. METHODS: One hundred and three patients (41 females, 62 males) with posterior cruciate ligament rupture from 2010 to 2020 were included in this retrospective case-control study. The sex and age of the posterior cruciate ligament rupture group were matched to those of the control group (41 females, 62 males; age range 16-69 years). Magnetic resonance imaging was used to measure the intercondylar notch width, femoral condylar width, and intercondylar notch angle in both the axial and coronal images. The 'α' angle was also measured using magnetic resonance imaging. The notch width index is the ratio of the intercondylar notch width to the femoral condylar width. Three types of intercondylar notch shapes (types A, U, and W) were evaluated in the axial magnetic resonance imaging images. RESULTS: The difference in the mean coronal notch width index between the study groups was statistically significant in the female population. The difference in the mean coronal femoral condylar width between the study groups was statistically significant in the male population. CONCLUSIONS: A larger coronal notch width index was the greatest risk factor for posterior cruciate ligament rupture in the female population. In the male population, decreased coronal condylar width was the greatest risk factor for posterior cruciate ligament rupture. The results did not indicate that patients with a PCL rupture have a stenotic intercondylar notch. Posterior cruciate ligament injury prevention strategies could be applied to females with a larger coronal notch width index and males with a decreased condylar width. LEVELS OF EVIDENCE: Level III.

Infraclavicular nerve block reduces postoperative pain after distal radial fracture fixation: a randomized controlled trial.

BACKGROUND: It is unclear whether regional anesthesia with infraclavicular nerve block or general anesthesia provides better postoperative analgesia after distal radial fracture fixation, especially when combined with regular postoperative analgesic medications. The aim of this study was to compare the postoperative analgesic effects of regional versus general anesthesia. METHODS: In this prospective, observer blinded, randomized controlled trial, 52 patients undergoing distal radial fracture fixation received either general anesthesia (n = 26) or regional anesthesia (infraclavicular nerve block, n = 26). Numerical rating scale pain scores, analgesic consumption, patient satisfaction, adverse effects, upper limb functional scores (Patient-Rated Wrist Evaluation, QuickDASH), health related quality of life (SF12v2), and psychological status were evaluated after surgery. RESULT: Regional anesthesia was associated with significantly lower pain scores both at rest and with movement on arrival to the post-anesthetic care unit; and at 1, 2, 24 and 48 h after surgery (p ≤ 0.001 at rest and with movement). Morphine consumption in the post-anesthetic care unit was significantly lower in the regional anesthesia group (p<0.001). There were no differences in oral analgesic consumption. Regional anesthesia was associated with lower incidences of nausea (p = 0.004), and vomiting (p = 0.050). Patient satisfaction was higher in the regional anesthesia group (p = 0.003). There were no long-term differences in pain scores and other patient outcomes. CONCLUSION: Regional anesthesia with ultrasound guided infraclavicular nerve block was associated with better acute pain relief after distal radial fracture fixation, and may be preferred over general anesthesia. TRIAL REGISTRATION: Before subject enrollment, the study was registered at ClinicalTrials.gov (NCT03048214) on 9th February 2017.

Comparison of radiological and clinical outcomes, complications, and implant removals in anatomically pre-contoured clavicle plates versus reconstruction plates - a propensity score matched retrospective cohort study of 106 patients.

BACKGROUND: Plate fixation is frequently used to treat displaced midshaft clavicular fractures, however the ideal plate choice remains subject to discussion; reconstruction locking compression plates (RLCPs) are cheaper and can be easily contoured, whereas anatomically pre-contoured locking compression plates (ALCPs) are thought to provide better stability and therefore lower rates of mechanical failure. To compare the incidence of mechanical failures, functional and radiological outcomes in patients with midshaft clavicular fractures treated with ALCPs versus RLCPs. METHODS: A propensity score matched retrospective cohort study was conducted across two centers. One hundred and six consecutively recruited patients with displaced midshaft clavicular fractures, who were treated with plate fixation and had a minimum follow-up of 6 months, were matched on gender, age, fracture grading, energy of injury, and fracture location. The resulting groups included 53 ALCP-treated fractures and 53 matched controls treated with RLCPs. RESULTS: During a mean follow-up of 20.5 months, there were no implant deformities in the ALCP group whereas the RLCP group had 6 patients (11.3%, p = 0.012) with implant deformities (5 occurrences of plate bending with fracture union, and 1 plate breakage with nonunion). Despite the higher rate of plate deformities in the RLCP group, there were no statistically significant differences in number of patients recovering full shoulder range of motion (ALCP 90.6%, RLCP 88.7%, p = 0.751), incidence of rest pain (ALCP 13.2%, RLCP 9.4%, p = 0.542), or implant removals (ALCP 49.1%, RLCP 56.6%, p = 0.439). CONCLUSION: ALCPs may be superior to RLCPs in terms of implant stability but appear to produce similar clinical results.

Cementation: for better or worse? Interim results of a multi-centre cohort study using a fenestrated spiral blade cephalomedullary device for pertrochanteric fractures in the elderly.

INTRODUCTION: Cephallomedullary nail fixation is currently the most popular treatment for pertrochanteric fractures. Despite continuous improvement in implant design, fixation failures still occur in a concerning number of cases. This study aims to evaluate the effect of cement augmentation of the new-generation Trochanteric Femoral Nail Advanced (TFNA) perforated spiral blade on complications including fixation failure in the elderly population. MATERIALS AND METHODS: We retrospectively evaluated 107 patients aged 65 + treated for pertrochanteric fractures via TFNA between 2015 and 2019 based on whether cementation was used. Baseline demographics, fracture classifications, and reduction quality were compared. Patients with a follow-up of at least 6 months were analyzed for the primary outcome of fixation failure. All patients, regardless of loss to follow-up within 6 months, were analyzed for other complications including mortality. RESULTS: Seventy-six patients (47 cemented, 29 non-cemented) had a minimum follow-up of 6 months (mean 13 months). There were no statistically significant differences between the two treatment groups in terms of patient demographics, ASA or AO/OTA fracture classification, reduction quality, or length of follow-up. There was a lower rate of fixation failure in the cement-augmented (CA) group versus the non-cement-augmented (NCA) group (2.1% vs 13.8%; p = 0.047). No cut-out or cut-through was observed in the CA group. Seven patients had adverse intraoperative events, with a significantly higher rate of fixation failure in these patients (40% vs 2.8%; p = 0.00). There were no statistically significant differences in 30-day mortality (6.3% CA vs 4.3% NCA; p = 0.632) or 3-month mortality (9.5% CA vs 12.8% NCA; p = 0.589). CONCLUSIONS: Cementation of TFNA blades may decrease risk of fixation failure, however, the surgeon must be aware of potential complications such as cement leakage into the hip joint and be able to manage them as they arise.

Matrix metallopeptidase 9 targeted by hsa-miR-494 promotes silybin-inhibited osteosarcoma.

Osteosarcoma (OS) is the most common malignant tumor that develops in bone. Its mortality is very high. Therefore, study of mechanisms of pathogenesis of the OS is urgently required. Previous studies of microarray showed that the expression levels of matrix metallopeptidase 9 (MMP-9) altered significantly in OS. In addition, overexpression of MMP-9 is recognized as an indicator in cancer. However, the exact roles of MMP-9 in OS are not fully investigated. Thus, we firstly studied the roles of MMP-9 in OS and revealed that silence of MMP-9 inhibited OS cell proliferation as determined by MTT assay and colony formation assay. Secondly, we conducted TUNEL assay and confirmed loss of functions of MMP-9 induced OS cell apoptosis. Next, we used lentivector packaging method to overexpress MMP-9 and found that overexpression of MMP-9 promoted OS cell migration. Fourthly, the results of luciferase assay showed that MMP-9 was targeted by hsa-miR-494, which inhibited OS. Fifthly, we revealed that the levels of hsa-miR-494 were upregulated by the drug silybin which inhibited OS. Finally, we revealed that silybin inhibited OS cell viability by altering the protein levels of ß-catenin and Runt-related transcription factor 2 (RUNX2) as determined by western blot and immunocytochemistry (ICC).

The status of triangular fibrocartilage complex after the union of distal radius fractures with internal plate fixation.

PURPOSE: Distal radius fractures are associated with a high incidence of triangular fibrocartilage complex (TFCC) tears. This study aims to evaluate the status of TFCC after the healing of distal radius fractures, and its clinical significance. METHODS: Wrist arthroscopies were performed on 43 distal radius fractures, with an average age of 54 years old. RESULTS: Twenty-six complete tears and 15 partial healed tears were noted. Five out of eight patients with intact TFCC tears had neither signs nor symptoms, while eight patients with TFCC tears had no complaint. While no association was found between ulnar wrist pain and TFCC tears, there was association between DRUJ instability and TFCC tears and fovea tears. The function outcome did not differ with respect to the integrity of TFCC. CONCLUSIONS: A large majority of TFCC tears remained unhealed after the union of distal radius fractures. However, not all patients with tear were symptomatic.

Platinum(II)-Based Supramolecular Scaffold-Templated Side-by-Side Assembly of Gold Nanorods through Pt⋠⋠⋠Pt and π-π Interactions.

The side-by-side assembly of gold nanorods (GNRs) was shown to be directed by the supramolecular scaffolds formed by sulfonate-containing alkynylplatium(II) terpyridine complexes. Driven by Pt⋅⋅⋅Pt and π-π stacking interactions, the PtII complex has a high propensity to assemble in water with the head-to-tail stacking arrangement to construct supramolecular scaffolds, in which the sulfonate groups on the terpyridine ligand at the peripheral position preferentially bind to the sides of the GNRs. The extent of the assembly of the GNRs into ladder rung-like nanostructures can be modulated by the concentration of the PtII complex. The Pt⋅⋅⋅Pt interaction-assisted formation of the scaffolds and its directed assembly of GNRs were characterized by UV/Vis spectroscopy, quantum-chemical modeling, electron microscopy, energy dispersed X-ray (EDX) analysis, and SERS. This work provides insights for the construction of higher-ordered nano-assemblies using both Pt⋅⋅⋅Pt interactions and template-directed approaches.

Metal-Metal and π-π Interactions Directed End-to-End Assembly of Gold Nanorods.

The end-to-end aggregation of gold nanorods (GNRs) has been demonstrated to be directed by a thioacetate-containing alkynylplatinum(II) terpyridine complex. The in situ deprotected complex is preferentially attached at the ends of the gold nanorods (GNRs) and induce the aggregation of GNRs in an "end-to-end" manner by Pt···Pt and π-π interactions, which have been characterized by electron microscopy, energy dispersed X-ray (EDX) analysis, and UV-vis absorption spectroscopy. The assembly of the nanorods into chain-like nanostructures can be controlled by the concentration of the Pt(II) complexes.

Combination of granulocyte colony-stimulating factor and CXCR4 antagonist AMD3100 for effective harvest of endothelial progenitor cells from peripheral blood and in vitro formation of primitive endothelial networks.

Endothelial progenitor cells (EPC) derived from the circulation may be used to enhance neovascularization. Since the combination of granulocyte colony-stimulating factor (GCSF) and CXCR4 antagonist AMD3100 efficiently mobilizes hematopoietic stem cells into peripheral circulation, it may increase the pool of endogenously circulating EPC. We tested this hypothesis by administering GCSF and AMD3100 to adult rabbits and rats, isolating mononuclear cells from peripheral blood by Ficoll density gradient centrifugation, and characterizing the blood-derived EPC based on morphology, immunophenotyping, gene expression and other functional analyses. These EPC showed clonal growth similar to that of human umbilical vein endothelial cells when cultured in complete EGM-2 medium on collagen I-precoated culture plates. The EPC exhibited a typical cobblestone-like morphology and were relatively homogeneous by the third passage. The cells expressed the typical endothelial marker CD31 based on flow cytometry and fluorescence microscopy, formed capillary-like structures when cultured in Matrigel, internalized DiI-acetylated low-density lipoprotein, bound Ulex europaeus agglutinin-1, and expressed CD31 and several other endothelial markers (VEGFR2, VE-cadherin, Tie-2, eNOS, vWF) at significantly higher levels than bone marrow-derived mesenchymal stem cells. These results suggest that the combination of GCSF and AMD3100 can efficiently release stem cells into peripheral circulation and generate EPC that show the desired morphological, immunophenotypic and functional characteristics. This minimally invasive approach may be useful for autologous cell transplantation for postnatal neovasculogenesis and tissue repair.

MiR-9-5p, miR-675-5p and miR-138-5p Damages the Strontium and LRP5-Mediated Skeletal Cell Proliferation, Differentiation, and Adhesion.

This study was designed to evaluate the effects of strontium on the expression levels of microRNAs (miRNAs) and to explore their effects on skeletal cell proliferation, differentiation, adhesion, and apoptosis. The targets of these miRNAs were also studied. Molecular cloning, cell proliferation assay, cell apoptosis assay, quantitative real-time PCR, and luciferase reporter assay were used. Strontium altered the expression levels of miRNAs in vitro and in vivo. miR-9-5p, miR-675-5p, and miR-138-5p impaired skeletal cell proliferation, cell differentiation and cell adhesion. miR-9-5p and miR-675-5p induced MC3T3-E1 cell apoptosis more specifically than miR-138-5p. miR-9-5p, miR-675-5p, and miR-138-5p targeted glycogen synthase kinase 3 ß (GSK3ß), ATPase Aminophospholipid Transporter Class I Type 8A Member 2 (ATP8A2), and Eukaryotic Translation Initiation Factor 4E Binding Protein 1 (EIF4EBP1), respectively. Low-density lipoprotein receptor-related protein 5 (LRP5) played a positive role in skeletal development. miR-9-5p, miR-675-5p, and miR-138-5p damage strontium and LRP5-mediated skeletal cell proliferation, differentiation, and adhesion, and induce cell apoptosis by targeting GSK3ß, ATP8A2, and EIF4EBP1, respectively.

Dual Esterase- and Steroid-Responsive Energy Transfer Modulation of Ruthenium(II) and Rhenium(I) Complex Functionalized Gold Nanoparticles.

A number of adamantane-containing ruthenium(II) and rhenium(I) complexes have been synthesized, characterized, and noncovalently functionalized with ß-cyclodextrin-capped gold nanoparticles (ß-CD-GNPs) through the host-guest interaction between cyclodextrin and adamantane. The resultant nanoconjugates have been characterized by transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), and 2D ROESY (1) H NMR experiments. The Förster resonance energy transfer (FRET) properties of the nanoconjugates can be modulated by both esterase-accelerated hydrolysis and competitive displacement of steroid, by monitoring the emission intensity and luminescence lifetime. The FRET efficiencies are found to vary with the nature of the chromophores and the length of the spacer between the transition metal complexes and the GNPs. This work constitutes a "proof-of-principle" assay method for the dual-functional detection of important classes of biomolecules, such as enzymes and steroids.

Masquelet technique for treatment of posttraumatic bone defects.

Masquelet technique, which is the use of a temporary cement spacer followed by staged bone grafting, is a recent treatment strategy to manage a posttraumatic bone defect. This paper describes a series of 9 patients treated with this technique of staged bone grafting following placement of an antibiotic spacer to successfully manage osseous long bone defects. The injured limbs were stabilized and aligned at the time of initial spacer placement. In our series, osseous consolidation was successfully achieved in all cases. This technique gives promising result in the management of posttraumatic bone defects.

Is helical blade superior to screw design in terms of cut-out rate for elderly trochanteric fractures? A meta-analysis of randomized controlled trials.

PURPOSE: This meta-analysis was conducted to investigate whether helical blade implant system had advantages in terms of cut-out rate when compared to screw implant system for trochanteric fractures of elderly population. METHODS: The databases of MEDLINE, Cochrane Library and OVID were searched from inception to September 2013, and all randomized controlled trials comparing outcomes between helical blade system and screw system in treating trochanteric fractures were selected. Three researchers assessed the methodological quality and extracted data of the enrolled studies independently. Data were analysed using Review Manager 5.1 version. RESULTS: Six studies including 759 patients were involved. Results revealed that compared with screw group, blade group had similar outcomes of "centre-centre" position (95% CI 0.89-1.06, P = 0.48) and tip-apex distance (95% CI-0.08 to 1.31, P = 0.08). Cut-out and other complications were also comparable between the two groups (95% CI 0.34-1.54, P = 0.41; 95% CI 0.73-1.32, P = 0.90). Operation time and fluoroscopy time of blade group were significantly less than that of screw group (95% CI -5.13 to -3.70, P < 0.00001; 95% CI -32.50 to -27.07, P < 0.00001). Outcome of post-operative function was similar between two groups (95% CI 0.94-1.15, P = 0.45). CONCLUSIONS: Blade group required less operation time and fluoroscopy time than that of screw group treating trochanteric fractures in the elderly, but the differences observed could be biased due to grouping and other limitations. Outcomes of cut-out complication, other complications, position of implant and post-operative function were similar between two groups.

Biomechanical comparison of a new undercut thread design vs. the V-shape thread design for pedicle screws.

BACKGROUND CONTEXT: Thread shape is regarded as an important factor influencing the fixation strength and osseointegration of bone screws. However, commercial pedicle screws with a V-shaped thread are prone to generating stress concentration at the bone-screw interface, thereby increasing the risk of screw loosening. Thus, modification of the pedicle-screw thread is imperative. PURPOSE: This study aimed to investigate the fixation stability of pedicle screws with the new undercut thread design in comparison to pedicle screws with a V-shaped thread. STUDY DESIGN: In vitro cadaveric biomechanical test and finite element analysis (FEA). METHODS: Pedicle screws with the undercut thread (characterized by a flat crest feature and a tip-facing undercut feature) were custom-manufactured, whereas those with the V-shaped thread were procured from a commercial supplier. Fixation stability was assessed by the cyclic nonpullout compressive biomechanical testing on cadaveric female osteoporotic vertebrae. The vertical displacement and rotation angle of the 2 types of pedicle screws were calculated every 100 cycles to evaluate their resistance to migration and rotation. FEA was conducted to investigate the stress distribution and bone damage at the bone-screw interface for both types of pedicle screws. RESULTS: Biomechanical testing revealed that the pedicle screws with the undercut thread exhibited significantly lower vertical displacement and rotation angles than the pedicle screws with the V-shape thread (P < 0.05). FEA results demonstrated a more uniform stress distribution in the bone surrounding the thread in the undercut design than in the V-shape design. Additionally, bone damage resulting from the pedicle screw was lower in the undercut design than in the V-shape design. CONCLUSIONS: Pedicle screws with an undercut thread are less prone to migration and rotation and thus more stable in the bone than those with a V-shape thread. CLINICAL SIGNIFICANCE: The undercut thread design may reduce the incidence of pedicle-screw loosening.

A biomechanical study comparing helical blade with screw design for sliding hip fixations of unstable intertrochanteric fractures.

Dynamic hip screw (DHS) is a well-established conventional implant for treating intertrochanteric fracture. However, revision surgery sometimes still occurs due to the cutting out of implants. A helical blade instead of threaded screw (DHS blade) was designed to improve the fixation power of the osteoporotic intertrochanteric fracture. In this study, the biomechanical properties of DHS blade compared to the conventional DHS were evaluated using an unstable AO/OTA 31-A2 intertrochanteric fracture model. Fifty synthetic proximal femoral bone models with such configuration were fixed with DHS and DHS blade in five different positions: centre-centre (CC), superior-centre (SC), inferior-center (IC), centre-anterior (CA), and centre-posterior (CP). All models had undergone mechanical compression test, and the vertical and rotational displacements were recorded. The results showed that DHS blade had less vertical or rotational displacement than the conventional DHS in CC, CA, and IC positions. The greatest vertical and rotational displacements were found at CP position in both groups. Overall speaking, DHS blade was superior in resisting vertical or rotational displacement in comparison to conventional DHS, and the centre-posterior position had the poorest performance in both groups.

Proximal femoral nail versus dynamic hip screw fixation for trochanteric fractures: a meta-analysis of randomized controlled trials.

BACKGROUND: The purpose of this meta-analysis was to find out whether the proximal femoral nail was better than the dynamic hip screw in the treatment of trochanteric fractures with respect to operation time, blood transfusion, hospital stay, wound complications, number of reoperation, and mortality rate. METHODS: All randomized controlled trials comparing proximal femoral nail and dynamic hip screw in the treatment of trochanteric fractures were included. Articles and conference data were extracted by two authors independently. Data was analyzed using RevMan 5.1 version. Eight trials involving 1348 fractures were retrieved. RESULTS: Compared with DHS fixation, PFN fixation had similar operation time (95% CI: -15.28-2.40, P = 0.15). Blood loss and transfusion during perioperative time were also comparable between the two fixations (95% CI: -301.39-28.11, P = 0.10; 95% CI: -356.02-107.20, P = 0.29, resp.). Outcomes of hospital stay (95% CI: -0.62-1.01, P = 0.64), wound complication (95% CI: 0.66-1.67, P = 0.82), mortality (95% CI: 0.83-1.30, P = 0.72), and reoperation (95% CI: 0.61-1.54, P = 0.90) were all similar between the two groups. CONCLUSION: PFN fixation shows the same effectiveness as DHS fixation in the parameters measured.