Forces required to dynamize sliding screws in gamma nail and selfdynamizable internal fixator.

BACKGROUND: Single limb support phase of the gait-cycle in patients who are treated for a pertrochanteric fracture is characterized by transversal loads acting on the lag screw, tending to block its dynamization. If the simultaneous axial force overcomes transversal loads of the sliding screw, the dynamization can still occur. METHODS: Biomechanical investigation was performed for three types of dynamic implants: Gamma Nail, and two types of Selfdynamizable Internal Fixators (SIF) - SIF-7 (containing two 7 mm non-cannulated sliding screws), and SIF-10 (containing one 10 mm cannulated sliding screw). Contact surface between the stem and the sliding screws is larger in SIF implants than in Gamma Nail, as the stem of Gamma Nail is hollow. A special testing device was designed for this study to provide simultaneous application of a controlled sliding screws bending moment and a controlled transversal load on sliding screws (Qt) without using of weights. Using each of the implants, axial forces required to initiate sliding screws dynamization (Qa) were applied and measured using a tensile testing machine, for several values of sliding screws bending moment. Standard least-squares method was used to present the results through the linear regression model. RESULTS: Positive correlation between Qt and Qa was confirmed (p < 0.05). While performing higher bending moments in all the tested implants, Qa was higher than it could be provided by the body weight. It was the highest in Gamma Nail, and the lowest in SIF-10. CONCLUSIONS: A larger contact surface between a sliding screw and stem results in lower forces required to initiate dynamization of a sliding screw. Patients treated for a pertrochanteric fracture by a sliding screw internal fixation who have longer femoral neck or higher body weight could have different programme of early postoperative rehabilitation than lighter patients or patients with shorter femoral neck.

Treatment of Length-Unstable Pediatric Femur Fractures in Children Aged 5 to 11 years: A Focused Review.

Pediatric femur fractures in children aged 5 to 11 years are typically classified as length-stable versus length-unstable. For length-stable fracture patterns, there is frequent consensus among pediatric orthopaedic specialists regarding the appropriateness of flexible intramedullary nails, submuscular plates (SMP), or lateral-entry rigid intramedullary nails (LE-RIMN). With length-unstable fracture patterns, however, the decision is more complex. Age, weight, fracture pattern, fracture location, surgical technique, surgeon experience, several implant-specific details, and additional factors are all important when choosing between flexible intramedullary nail, SMP, and LE-RIMN. These familiar methods of fixation may all be supported by conflicting and sometimes heterogeneous data. When planning to treat length-unstable fractures in young children, surgeons should understand evidence-based details associated with each implant and how each patient-specific scenario affects perioperative decisions.

Posterior Cruciate Ligament Injury After Retrograde Nailing of Periprosthetic Distal Femur Fractures: A Report of 2 Cases.

CASE: A 51-year-old man and 64-year-old woman with bilateral cruciate-retaining total knee arthroplasties (CR-TKAs) who sustained unilateral periprosthetic distal femur fractures above their CR-TKA and experienced knee instability secondary to an iatrogenic posterior-cruciate-ligament (posterior cruciate ligament [PCL]) injury from retrograde intramedullary nailing. Both patients recovered knee stability after undergoing revision surgery. CONCLUSION: Many CR-TKA designs have sufficient medial-lateral intercondylar distance to place a retrograde nail, femoral components with a relatively posterior transition from the trochlear groove to the intercondylar box will necessitate a nail starting point closer to the PCL origin. This may contribute to iatrogenic postoperative knee instability for patients with CR-TKA designs.

IL-17RA Signaling in Prx1+ Mesenchymal Cells Influences Fracture Healing in Mice.

Fracture healing is a complex series of events that requires a local inflammatory reaction to initiate the reparative process. This inflammatory reaction is important for stimulating the migration and proliferation of mesenchymal progenitor cells from the periosteum and surrounding tissues to form the cartilaginous and bony calluses. The proinflammatory cytokine interleukin (IL)-17 family has gained attention for its potential regenerative effects; however, the requirement of IL-17 signaling within mesenchymal progenitor cells for normal secondary fracture healing remains unknown. The conditional knockout of IL-17 receptor a (Il17ra) in mesenchymal progenitor cells was achieved by crossing Il17raF/F mice with Prx1-cre mice to generate Prx1-cre; Il17raF/F mice. At 3 months of age, mice underwent experimental unilateral mid-diaphyseal femoral fractures and healing was assessed by micro-computed tomography (µCT) and histomorphometric analyses. The effects of IL-17RA signaling on the osteogenic differentiation of fracture-activated periosteal cells was investigated in vitro. Examination of the intact skeleton revealed that the conditional knockout of Il17ra decreased the femoral cortical porosity but did not affect any femoral trabecular microarchitectural indices. After unilateral femoral fractures, Il17ra conditional knockout impacted the cartilage and bone composition of the fracture callus that was most evident early in the healing process (day 7 and 14 post-fracture). Furthermore, the in vitro treatment of fracture-activated periosteal cells with IL-17A inhibited osteogenesis. This study suggests that IL-17RA signaling within Prx1+ mesenchymal progenitor cells can influence the early stages of endochondral ossification during fracture healing.

Radiographic outcomes and non-union factor analysis in fragmentary segmental femoral shaft fractures (AO/OTA 32C3) treated with reamed antegrade nailing.

This study retrospectively assessed radiographic outcomes and risk factors associated with non-union in femoral shaft fragmentary segmental fractures (AO/OTA 32C3) treated with reamed antegrade intra-medullary nailing. Radiological outcomes, including union and alignment, were evaluated. The risk factors for non-union were investigated, including demographics and treatment-related characteristics, such as the number of interlocking screws, segmentation length, main third fragment length, distance of the main third fragment, width ratio and exposed nail length in one cortex from immediate post-operative radiographs. Multivariate logistic regression was used for statistical analysis. Among 2295 femoral shaft fracture patients from three level-1 trauma centers, 51 met the inclusion criteria. The radiological union was achieved in 37 patients (73%) with a mean union time of 10.7 ± 4.8 months. The acceptable axial alignment was observed in 30 patients (59%). Multiple logistic regression analysis identified only exposed nail length as a significant risk factor for non-union (odds ratio: 1.599, p = 0.003) and the cut-off value was 19.1 mm (sensitivity, 0.786; specificity, 0.811). The study revealed high rates of non-union (27%) and malalignment (41%). Therefore, patients who underwent intramedullary nailing with an exposed nail length greater than 19.1 mm or about twice the nail diameter should be cautioned of the potential non-union.

Fracture healing on non-union fracture model promoted by non-thermal atmospheric-pressure plasma.

Non-thermal atmospheric-pressure plasma (NTAPP) is attracting widespread interest for use in medical applications. The tissue repair capacity of NTAPP has been reported in various fields; however, little is known about its effect on fracture healing. Non-union or delayed union after a fracture is a clinical challenge. In this study, we aimed to investigate how NTAPP irradiation promotes fracture healing in a non-union fracture model and its underlying mechanism, in vitro and in vivo. For the in vivo study, we created normal and non-union fracture models in LEW/SsNSlc rats to investigate the effects of NTAPP. To create a fracture, a transverse osteotomy was performed in the middle of the femoral shaft. To induce the non-union fracture model, the periosteum surrounding the fracture site was cauterized after a normal fracture model was created. The normal fracture model showed no significant difference in bone healing between the control and NTAPP-treated groups. The non-union fracture model demonstrated that the NTAPP-treated group showed consistent improvement in fracture healing. Histological and biomechanical assessments confirmed the fracture healing. The in vitro study using pre-osteoblastic MC3T3-E1 cells demonstrated that NTAPP irradiation under specific conditions did not reduce cell proliferation but did enhance osteoblastic differentiation. Overall, these results suggest that NTAPP is a novel approach to the treatment of bone fractures.

THE ROLE OF DISTAL LOCKING IN INTRAMEDULLARY NAILS FOR HIP FRACTURE FIXATION: A REVIEW OF CURRENT LITERATURE.

Traditionally, it was believed that both proximal and distal locking are essential for achieving stability during intra-medullary fixation for extra-capsular hip fractures. However, recent literature has presented varying perspectives on the necessity of distal locking. Distal locking plays a significant role in managing hip fractures with uncertainties regarding longitudinal and rotational stability. This includes cases of comminuted intertrochanteric fractures with subtrochanteric extension, reverse oblique and high oblique fractures, broad medullary canals, comminution of the lateral wall, diaphyseal fractures, and large posteromedial fragments extending below the level of the lesser trochanter. In stable pertrochanteric fractures, with the lag screw passing through the lateral cortex of the distal fragment, may not require a distal locking screw. Distal locking has been associated with potential complications, including irritation of the fascia lata, prolonged operation time, increased radiation exposure, greater blood loss, implant loosening, secondary femoral stress fractures, and damage to the femoral artery. Thus, although distal locking is of doubtful significance in stable pertrochanteric fractures it is essential in unstable fracture patterns.

[National competitive bidding analysis of osteosynthesis materials in pediatric patients with femur fractures]. / Análisis de licitación pública nacional de materiales de osteosíntesis en los pacientes pediátricos con fracturas de fémur.

INTRODUCTION: health promotion policy requires the identification of barriers to the adoption of public policies. Paraguay's national healthcare system is inequitable, expensive, and inefficient. The Ministry of Public Health and Social Welfare (MSPyBS) is the entity responsible for covering the needs of a significant portion of the population. In January 2022, the MSPyBS financed the purchase of titanium elastic nails through a National Public Tender for Osteosynthesis Materials (LPN 02/22) to provide them for free in the pediatric service. Using research as a tool, we seek to analyze the impact of the implementation of LPN 02/22 at the Trauma Hospital, believing that this action would help streamline administrative and bureaucratic processes, making them more efficient with the assistance of the hospital's human resources. MATERIAL AND METHODS: a retrospective, analytical, and comparative study conducted at a high-complexity trauma center in Asunción, Paraguay. Patients aged 4 to 14 years with an indication for stabilization with elastic nails were included. Demographic data, the mechanism of injury, time elapsed from hospital arrival to surgical treatment, length of hospital stay, and the average hospital cost were analyzed based on the daily expense of pediatric patient hospitalization. RESULTS: 52 patients, divided into 25 cases in 2021 before implementation and 27 cases after implementation. The time elapsed from hospital arrival to definitive treatment was six days in the pre-implementation period, with an average stay from admission to discharge of 7.4 days. After implementation, the time from hospital arrival to definitive treatment was 4.3 days, and the average discharge time for the Post group was six days. The potential savings per patient amount to 332 dollars, offset by the institution's implant supply cost of 197 dollars, resulting in an approximate savings of 135 dollars per patient for the ministry. CONCLUSIONS: we view the implementation of free titanium elastic nails for pediatric femur fracture patients positively. We encourage the institution to continue with similar policies and strive to achieve even greater benefits for users.

INTRODUCCIÓN: la política de promoción de la salud requiere la identificación de los obstáculos para la adopción de políticas públicas. El sistema nacional de salud de Paraguay es inequitativo, caro e ineficiente. El Ministerio de Salud Pública y Bienestar Social (MSPyBS) es el ente que cubre las necesidades de gran parte de la población. El MSPyBS en Enero del 2022 financió, mediante la Licitación Pública Nacional de Materiales de Osteosíntesis (LPN 02/22), la compra de clavos elásticos de titanio para disponer de su uso gratuito en el Servicio de Pediatría; usando a la investigación como herramienta, buscamos analizar el impacto de la implementación de la LPN 02/22 en el Hospital de Trauma, creyendo que esta acción ayudaría a dinamizar los procesos administrativos y burocráticos, haciéndolos más eficientes con la ayuda de los recursos humanos del hospital. MATERIAL Y MÉTODOS: estudio retrospectivo, analítico y comparativo, realizado en un centro de trauma de alta complejidad de Asunción, Paraguay. Fueron incluidos los pacientes con edad comprendidas entre cuatro y 14 años, con indicación de estabilización con clavos elásticos. Se analizaron los datos demográficos, el mecanismo de trauma, el tiempo transcurrido desde la llegada al hospital hasta el tratamiento quirúrgico, así como el tiempo de estadía hospitalaria. Se evaluó el costo hospitalario promedio, basados en el gasto diario de la internación de un paciente pediátrico. RESULTADOS: cincuenta y dos pacientes, separados en 25 casos en el 2021 previo a la implementación y 27 casos posterior a la implementación. El tiempo transcurrido desde la llegada al hospital hasta el tratamiento definitivo fue de seis días para la etapa previa a la implementación; el promedio desde el ingreso hasta el alta fue de 7.4 días. Desde la implementación se tuvo un transcurso de 4.3 días desde la llegada al hospital hasta el tratamiento definitivo. El egreso del grupo Post tuvo un promedio de seis días. El ahorro probable en relación con cada paciente es de 332 dólares; a esto debemos contrarrestar el monto que paga la institución para la provisión del implante (197 dólares), por lo que el ahorro del ministerio sería de aproximadamente 135 dólares por cada paciente. CONCLUSIONES: vemos como positiva la implementación de la gratuidad de los clavos elásticos de titanio en los pacientes en edad pediátrica con fractura de fémur. Alentamos a la institución a seguir con políticas similares y tratar de lograr mayores beneficios para los usuarios.

Unravelling variations: an examination of entry point selection in proximal femoral cephalomedullary nailing.

BACKGROUND: The exact positioning of the cephalomedullary (CM) nail entry point for managing femoral fractures remains debatable, with significant implications for fracture reduction and postoperative complications. This study aimed to explore the variability in the selection of the entry point among trauma surgeons, hypothesizing potential differences and their association with surgeon experience. METHODS: In this prospective multicenter study, 16 participants, ranging from residents to senior specialists, partook in a simulation wherein they determined the optimal entry point for the implantation of a proximal femoral nail antirotation (PFN-A; DePuy Synthes) in various femora. The inter- and intra-observer variability was calculated, along with comprehensive descriptive statistical analysis, to assess the variability in entry point selection and the impact of surgeon experience. RESULTS: In this study, the mean distance from the selected entry points to the calculated mean entry point was 3.98 mm, with a smaller distance observed among surgeons with more than 500 implantations (ANOVA, p = 0.050). Intra-surgeon variability for identical femora averaged at 5.14 mm, showing no significant differences across various levels of surgical experience or training. Notably, 13.6% of selected entry points would not allow a proper intramedullary positioning of the implant, thereby rendering anatomical repositioning unfeasible. Among these impossible entry points, a significant skew towards anterior placement was observed (70.6% of the impossible entry points), with a smaller fraction being overly lateral (27.5%) or medial (13.7%). On a patient level, the impossibility rate varied widely from 0 to 35% among the different femora examined, with a significantly higher rate seen in younger patients (mean age 55.02 versus 60.32; t-test for independent samples, p = 0.04). CONCLUSIONS: Significant variations exist in surgeons' selection of entry points for proximal femoral nailing, underscoring the task's complexity. Experience does not prevent the choice of unfeasible entry points, emphasizing the inadequacy of a universal approach and pointing towards the necessity for a patient-specific strategy for improved outcomes. TRIAL REGISTRATION NUMBER: DRKS00032465.

Comparative Outcomes of Elastic Stable Intramedullary Nailing vs. Plate Fixation in Pediatric Femoral Shaft Fractures. A Prospective Study.

BACKGROUND: Pediatric femoral fractures are common in emergency rooms, with treatment options varying by age. This study compares elastic stable intramedullary nailing (ESIN) and plate fixation for diaphyseal femoral fractures in children aged 5-10. MATERIAL AND METHODS: Conducted at Al-Kindi Teaching Hospital, Baghdad, from December 2017 to December 2019, this prospective study included 32 children with closed transverse diaphyseal femoral fractures. Patients were divided into two groups: 16 treated with ESIN (Group 1) and 16 with plate fixation (Group 2). Criteria excluded comminuted, open, or pathological fractures. RESULTS: Group 1 had a mean age of 7.1 years and weight of 23.7 kg; Group 2 had a mean age of 7.8 years and weight of 30.9 kg. ESIN resulted in shorter operative times (58.4 minutes), earlier weight-bearing, and quicker fracture union (8.8 weeks) compared to plate fixation (76.3 minutes, 11.9 weeks). Blood loss was significantly less in Group 1 (32.8 ml) versus Group 2 (205.0 ml). No significant differences in wound healing or leg length discrepancies were observed. CONCLUSIONS: 1. Our study indicates a preference for Elastic Stable Intramedullary Nailing (ESIN) over plate fixation for pediatric femoral shaft fractures in children aged 5-10 years. 2. ESIN is associated with shorter operative times and faster commencement of weight-bearing, critical in pediatric recovery. 3. While ESIN is generally preferable, plate fixation may be better suited in certain clinical scenarios, emphasizing the importance of personalized treatment. 4. Based on our findings, ESIN is recommended for treating transverse diaphyseal femur fractures in the specified pediatric age group. 5. Recommends further studies, including randomized controlled trials, for a more comprehensive understanding of these treatments' long-term outcomes.

Effects of Focal Cerebellar Injury on Fracture Healing and Oxidative Stress in Rat Model: An Experimental Animal Study.

AIM: To examine the effect of cerebellar damage on the process of fracture healing. MATERIAL AND METHODS: A total of forty-two male rats were selected at random and subsequently allocated into three distinct groups. The experimentals were divided into two subgroups within each group, with the intention of sacrificing them during the third and sixth weeks. Group 1 had isolated femoral fracture, Group 2 had femoral fracture after craniotomy, and Group 3 had femoral fracture accompanying cerebellar injury after craniotomy. Left femoral fractures in rats in all groups were treated using an intramedullary Kirschner wire. Radiological, histological, and biochemical evaluations were conducted at 3 and 6 weeks to assess the processes of fracture healing. To determine the effects of fracture healing and cerebellar injury on oxidant-antioxidant systems, catalase (CAT), malondialdehyde, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities were measured. RESULTS: Between the time frame of 3 to 6 weeks, Group 3 had higher radiography scores, alkaline phosphatase levels, callus/ diaphyse ratio, callus improvement, and bone mineral density in comparison to the other groups. The activity of SOD was found to be statistically negligible in all groups, suggesting that SOD does not have a substantial impact on fracture healing in cerebellar injury. However, notable increases in the activity of GPx and CAT enzymes were observed, showing their considerable involvement in the process of fracture healing. CONCLUSION: Cerebellar injury reduces the oxidative stress in the fracture area and contributes positively to fracture healing by means of radiologically, biochemically and histopathologically.

Femoral Shaft Fracture Developed Late-Onset Infection in 27 Years after Intramedullary Nailing: A Case Report.

Postoperative late-onset infections more than 1 year after intramedullary nail surgery for femoral shaft fractures are very rare. We show an extremely rare case of developed late-onset infection 27 years after surgery, report on risk factors for late-onset infection, and infer why the infection occurred.

Unique Spatial Transcriptomic Profiling of the Murine Femoral Fracture Callus: A Preliminary Report.

Fracture callus formation is a dynamic stage of bone activity and repair with precise, spatially localized gene expression. Metastatic breast cancer impairs fracture healing by disrupting bone homeostasis and imparting an altered genomic profile. Previous sequencing techniques such as single-cell RNA and in situ hybridization are limited by missing spatial context and low throughput, respectively. We present a preliminary approach using the Visium CytAssist spatial transcriptomics platform to provide the first spatially intact characterization of genetic expression changes within an orthopedic model of impaired fracture healing. Tissue slides prepared from BALB/c mice with or without MDA-MB-231 metastatic breast cancer cells were used. Both unsupervised clustering and histology-based annotations were performed to identify the hard callus, soft callus, and interzone for differential gene expression between the wild-type and pathological fracture model. The spatial transcriptomics platform successfully localized validated genes of the hard (Dmp1, Sost) and soft callus (Acan, Col2a1). The fibrous interzone was identified as a region of extensive genomic heterogeneity. MDA-MB-231 samples demonstrated downregulation of the critical bone matrix and structural regulators that may explain the weakened bone structure of pathological fractures. Spatial transcriptomics may represent a valuable tool in orthopedic research by providing temporal and spatial context.

[Off target of distal interlocking screw in short cephalomedullary nail fixation for intertrochanteric femur fractures].

Objective: To analyze the causes and treatment of off target of the distal interlocking screws when short cephalomeduallry nails were installed through jig-guided targeting device, and to put forward the technical points to prevent off target. Methods: Retrospective analysis of 9 patients with intertrochanteric fractures treated between July 2014 and June 2023 was conducted, in which off target occurred during the insertion of the distal interlocking screw by jig-guided targeting device in short cephalomedullary nailling (<24 cm). There were 1 male and 8 females, with an average age of 82.7 years (range, 73-94 years). There were 3 cases of type A1, 5 cases of type A2, and 1 case of type A3 according to 2018-AO/Orthopaedic Trauma Association (AO/OTA) fracture classification. As for the misaligned distal interlocking screw, six parameters were collected and analyzed, including the time of finding, the position, the type of passing through the cortical bone, the special circumstances during operation (such as the need to remove the intramedullary nail for reaming the diaphysis, hammering, etc.), the treatment, and the patient follow-up results. Results: In the 9 patients, the off target of the distal interlocking screw was found in 7 cases during operation and in 2 cases after operation; the locking screw was located behind the nail in 7 cases and in front of the nail in 2 cases; the off target locking screw was passing tangentially in transcortical patern in 6 cases and in bicortical pattern through the medullary cavity in 3 cases. Three cases were attributed to the mismatch between the nail and the femur, two of which were attributed to the narrow femoral medullary cavity, one of which was attributed to the large anterolateral femoral bowing, and the other 6 cases were attributed to technical errors such as the loosening of the jig-guided targeting device, the tension of the fascia lata, and the blunt of the drill. In the 7 cases found during operation, the misaligned interlocking screw was removed first and the screw hole was left vacant, then in 2 cases, the interlocking screw was not used further; in 1 case, the distal dynamic hole was successfully inserted with a dynamic guide frame, and in 4 cases, the interlocking screw was successfully put after 2-3 attempts, leaving a large hole in the lateral cortex. No special treatment was performed in 2 cases found after operation. One patient was out of bed early after operation, 7 patients were in bed for 1 month, and 1 patient deteriorated to A3 type after operation and was in bed for 3 months. All the 9 patients were followed up 6-12 months, with an average of 8 months. Fracture healing was achieved in 8 patients. One patient with vacant interlocking screw had a secondary spiral fracture of the femoral shaft 3 months later, and was refixed with a long cephalomedullary nail and circlage wiring. Conclusion: Distal interlocking screw off target is rare, but when it occurs, it leaves a large cortical hole in the osteoporotic femoral shaft, reducing bone strength; the use of precision instruments and attention to technical details can reduce this adverse phenomenon.

Unstable Vancouver B1 periprosthetic femoral fracture fixation: A biomechanical comparison between a novel C-shaped memory alloy implant and cerclage wiring.

BACKGROUND: To compare the biomechanical stability of a novel, C-shaped nickel-titanium shape memory alloy (SMA) implant (C-clip) with traditional cerclage wiring in the fixation of a Vancouver B1 (VB1) periprosthetic femoral fracture (PFF). METHODS: In total, 18 synthetic femoral fracture models were constructed to obtain unstable VB1 fracture with an oblique fracture line 8 cm below the lesser trochanter. For each model, the distal portion was repaired using a 10-hole locking plate and four distal bi-cortical screws. The proximal portion was repaired using either three, threaded cerclage wirings or three, novel C-shaped implants. Specimens underwent biomechanical testing using axial compression, torsional and four-point bending tests. Each test was performed on three specimens. RESULTS: The C-clip was statistically significantly stronger (i.e., stiffer) than cerclage wiring in the three biomechanical tests. For axial compression, medians (ranges) were 39 (39-41) and 35 (35-35) N/mm, for the C-clip and cerclage wiring, respectively. For torsion, medians (ranges) were, 0.44 (0.44-0.45) and 0.30 (0.30-0.33) N/mm for the C-clip and cerclage wiring, respectively. For the four-point bending test, medians (ranges) were 39 (39-41) and 28 (28-31) N/mm; for the C-clip and cerclage wiring, respectively. CONCLUSION: Results from this small study show that the novel, C-shaped SMA appears to be biomechanically superior to traditional cerclage wiring in terms of stiffness, axial compression, torsion and four-point bending, and may be a valuable alternative in the repair of VB1 PFF. Further research is necessary to support these results.

Acetabular "Fleck" Sign: Outcomes of Surgical Repair.

BACKGROUND: Traumatic, posterior hip dislocations in the pediatric population are typically managed by closed reduction to achieve a concentric hip joint. The presence of an acetabular "fleck" sign, despite concentric reduction, has been shown to signify significant hip pathology. The purpose of this study was to evaluate the outcomes of open labral repair through a surgical hip dislocation (SHD) in a consecutive series of patients with an acetabular "fleck" sign associated with a traumatic hip dislocation/subluxation. METHODS: A retrospective review of patients between 2008 and 2022 who presented to a single, level 1 pediatric trauma center with a traumatic posterior hip dislocation/subluxation was performed. Patients were included if they had an acetabular "fleck" sign on advanced imaging and underwent open labral repair through SHD. Medical records were reviewed for sex, age, laterality, mechanism of injury (MOI), and associated orthopaedic injuries. The modified Harris hip score (mHHS) was utilized as the primary clinical outcomes measure. Patients were assessed for the presence of heterotopic ossification (HO) and complications, including implant issues, infection, avascular necrosis (AVN), and post-traumatic dysplasia. RESULTS: Twenty-nine patients (23 male, average age: 13.0±2.7 y; range: 5.2 to 17.3) were identified. Eighteen injuries were sports related, 9 caused by motor vehicle accidents, and 1 pedestrian struck. All patients were found to have an acetabular "fleck" sign on CT (26 patients) or MRI (5 patients). Associated injuries included: femoral head fracture (n=6), pelvic ring injury (n=3), ipsilateral femur fracture (n=2), and ipsilateral PCL avulsion (n=1). At the latest follow-up (2.2±1.4 y), all patients had returned to preinjury activity/sport. Three patients developed asymptomatic, grade 1 HO in the greater trochanter region. There was no incidence of AVN. One patient developed post-traumatic acetabular dysplasia due to early triradiate closure. mHHS scores showed excellent outcomes (n=21, 94.9±7.4, range: 81 to 100.1). CONCLUSIONS: The acetabular "fleck" sign indicates a consistent pattern of osteochondral avulsion of the posterior/superior labrum. Restoring native hip anatomy and stability is likely to improve outcomes. SHD with open labral repair in these patients produces excellent clinical outcomes, with no reported cases of AVN. LEVEL OF EVIDENCE: Level IV-therapeutic.

Distal Femoral Stress Fractures Has High Operation Rates in Adolescent and Young Adult Athletes.

BACKGROUND: Although stress fractures of the distal femur are rare, symptoms can overlap with other peri-articular knee pathology, delaying diagnosis. Untreated stress fractures have the potential to progress into completed fractures with a higher likelihood for requiring surgery and longer recovery times in otherwise healthy adolescents and young adults. This case series represents the largest cohort of adolescent athletes with distal femoral stress fractures who presented with activity-related knee pain. METHODS: Patients treated nonoperatively and operatively for metaphyseal distal femur stress fractures at a tertiary referral center over a four-year period were retrospectively identified from the medical record. RESULTS: Eight patients (mean age 16.8 y; range 14 to 22 y; 87.5% male; mean body mass index [BMI] 20.9) with a total of 10 distal femur stress fractures were identified. All patients were involved in competitive sports or military training. There was an average of 3.8 encounters with a medical provider between presentation with activity-related knee pain and diagnosis with distal femur stress fracture. All except 1 patient (87.5%) were initially incorrectly diagnosed with another type of peri-articular knee pathology. Six stress fractures (60%) were treated conservatively with protected weight bearing, activity modification, and gradual return to activity. Four completed stress fractures (40%) required operative fixation-3 healed uneventfully, while 1 had an asymptomatic delayed union. Vitamin D insufficiency (<30 ng/mL) was identified in 7 of 8 patients (87.5%) and 3 patients (37.5%) had an underweight BMI (<18.5). The mean clinical follow-up was 13.1 weeks (range, 2.8 to 32.0 wk). CONCLUSIONS: High clinical suspicion for distal femoral stress fractures is needed to avoid misdiagnosis or delayed diagnosis in young, active individuals with activity-related knee pain refractory to conservative management. In this patient population, activity-related knee pain recalcitrant to activity modification, rest, and physical therapy warrants further workup with magnetic resonance imaging and orthopaedic evaluation. Though rare, misdiagnosis can result in catastrophic fractures with prolonged rehabilitation needs. An open line of communication and streamlined access for referral between primary care providers and orthopaedic surgeons is critical in preventing misdiagnosis and delayed treatment. Furthermore, the treatment of concomitant metabolic disorders and nutritional deficiency should not be neglected when treating distal femoral stress fractures. LEVEL OF EVIDENCE: Level-IV (case series).

A magnesium screw with optimized geometry exhibits improved corrosion resistance and favors bone fracture healing.

Stress-induced corrosion impairs the mechanical integrity of magnesium (Mg) and its alloys as potential orthopedic implants. Although there has been extensive work reporting the effects of stress on Mg corrosion in vitro, the geometric design principles of the Mg-based orthopedic devices still remain largely unknown. In this work, a numerical simulation model mimicking fractured bone fixation and surgical animal models were applied to investigate the effects of the geometric design of Mg screws on the stress distribution and the stress-induced degradation behavior. Finite element (FE) analysis was used for calculation of stress concentrations around the Mg screws, with different thread type, thread pitch, and thread width. Afterward, the Mg screws of the pre-optimization and post-optimization groups exhibiting the highest and lowest stress concentrations, respectively, were implanted in the fractured distal femora and back subcutaneous tissue of rabbits. Encouragingly, there was a significant difference between the pre-optimization and the post-optimization groups in the degradation rate of the stressed screw parts located around the fracture line. Interestingly, there was no significant difference between the two groups in the degradation rate of the non-stressed screw parts. Consistently, the Mg screw post-optimization exhibited a significantly lower degradation rate than that pre-optimization in the back subcutaneous implantation model, which generated stress in the whole screw body. The alteration in geometric design did not affect the corrosion rate of the Mg screws in an immersion test without load applied. Importantly, an accelerated new bone formation with less fibrous encapsulation around the screws was observed in the Mg group post-optimization relative to the Mg group pre-optimization and the poly (lactic acid) group. Geometry optimization may be a promising strategy to reduce stress-induced corrosion in Mg-based orthopedic devices. STATEMENT OF SIGNIFICANCE: Stress concentrations influence corrosion characteristics of magnesium (Mg)-based implants. The geometric design parameters, including thread type, thread pitch, and thread width of the Mg screws, were optimized through finite element analysis to reduce stress concentrations in a fractured model. The Mg screws with triangular thread type, 2.25 mm pitch, and 0.3 mm thread width, exhibiting the lowest maximum von Mises stress, showed a significant decrease in the volume loss relative to the Mg screws pre-optimization. Compared with the Mg screw pre-optimization and the poly(lactic acid) screw, the Mg screw post-optimization favored new bone formation while inhibiting fibrous encapsulation. Collectively, optimization in the geometric design is a promising approach to reduce stress-induced corrosion in Mg-based implants.

Flexible nailing: Pushing the indications for diametaphyseal lower-extremity fractures.

Elastic stable intramedullary nailing (ESIN) has been shown to be an effective form of surgical management for lower-extremity diametaphyseal fractures in pediatric patients, but studies are limited because ESIN treatment for these fractures is relatively uncommon. We sought to determine whether ESIN can be used effectively in the most distal or proximal short-segment forms of these fractures. We queried the electronic medical record system at Johns Hopkins Hospital using Current Procedural Terminology codes for femur and tibia fractures treated with ESIN in patients under 18 years old between January 2015 and October 2022. Preoperative and postoperative radiographs were subsequently reviewed to identify patients with a proximal or distal third femoral or tibial shaft fracture treated with ESIN and to define criteria for short-segment diametaphyseal fractures. We used Beaty radiological criteria to evaluate radiographic outcomes and Flynn titanium elastic nails (TENs) outcome scale to assess clinical recovery after radiographic evidence of union. There were 43 children who met the inclusion criteria. Among them, 10 patients had short-segment diametaphyseal fractures. There were 22 (51.2%) who sustained femur fractures and 21 (48.8%) who sustained tibia fractures. Using Beaty radiologic criteria, ESIN was associated with more satisfactory outcomes in patients with distal or proximal third shaft fractures (32/33) than in patients with short-segment diametaphyseal fractures (7/10) (P = .03). Using the TENs outcome scale, 21 (63.4%) patients with distal or proximal third shaft fractures had excellent results, 11 (33.3%) had satisfactory results, and 1 (3%) had a poor result. Among patients with short-segment diametaphyseal fractures, 4 (40%) had excellent results, 5 (50%) had satisfactory results, and 1 (10%) had a poor result. There were no differences in TENs outcomes between the groups (P = .24). Patients with short-segment lower-extremity diametaphyseal fractures treated with ESIN had worse radiographic outcomes but did no worse clinically than patients with distal or proximal third shaft fractures. Consequently, ESIN should be considered a safe and effective surgical management option for pediatric patients with even the most distal or proximal forms of these fractures.

[Clinical observation of different intramedullary fixation methods for the treatment of intertrochanteric fracture].

OBJECTIVE: To explore clinical efficacy of proximal femoral nail anti-rotation(PFNA),InterTan and proximal femoral bionic intramedullary nail (PFBN) in treating femoral intertrochanteric fracture. METHODS: Clinical data of 120 patients with intertrochanteric fracture who were underwent closed reduction intramedullary nail-internal fixation from January 2020 to January 2021 were retrospectively analyzed. According to methods of internal fixation,patients were divided into 3 groups. There were 25 patients in PFBN group,including 16 females and 9 males,aged from 69 to 79 years old with an average of (73.67±5.16) years old. There were 55 patients in PFNA group,including 38 females and 17 males,aged from 68 to 80 years old with an average of (74.23±5.57) years old. There were 40 patients in InterTan group,including 26 females and 14 males,aged from 68 to 79 years old with an average of (73.45±5.34) years old. Operative time,intraoperative blood loss,incision length,hospital stay,weight-bearing time,fracture healing time and complications among 3 groups were compared,and clinical effect was evaluated by Harris score of hip function before operation,1,6 and 12 months after opertaion,respectively. RESULTS: Patients among 3 groups were successfully completed operation and were followed up for more than 12 months. There were no significant difference in hospital stay,operative time,intraoperative blood loss and incision length among 3 groups (P>0.05). Weight bearing time of PFBN group (7.98±1.34) d and InterTan group (8.22±0.46) d were earlier than that of PFNA group (10.27±0.66) d(P<0.01). Fracture healing time of PFBN group (10.14±2.33) weeks and InterTan group (11.87±2.48) weeks were earlier than that of PFNA group (13.68±2.36) weeks (P<0.01). One month after operation,Harris score in PFBN group (70.52±5.34) and InterTan group (69.81±6.17) was higher than that of PFNA group (51.46±5.36),and there was no significant difference between PFBN group and InterTan group (P>0.05). There were no significant difference in Harris scores among 3 groups before operation,6 and 12 months after opertaion(P>0.05). Cases of complication of InterTan group and PFNA group were lower than that of PFNA group (P<0.05). CONCLUSION: PFBN and InterTan for the treatment of intertrochanteric fracture have advantages of faster fracture healing,earlier weight-bearing time and fewer postoperative complications than traditional PFNA,but three operations could achieve higher effective rates without significant difference in long-term results.