Background The incidence of femoral neck fractures (FNFs) is increasing, primarily due to an aging population and an increased incidence of high-energy trauma. Although fixation with three cannulated screws (TCS) is the most commonly used surgical technique, it has limitations, including suboptimal operative accuracy and dependence on repeated intraoperative fluoroscopy. In response, advanced navigation systems have been developed to improve surgical precision and outcomes. Objective This multicenter, prospective, randomized controlled superiority trial will compare surgical outcomes between an intelligent navigation system and the conventional freehand technique for FNF, as well as long-term fracture healing and complication rates. Methods This multicenter, prospective, randomized controlled superiority trial will compare navigation system–assisted TCS fixation with conventional freehand TCS fixation in patients with FNF from June 2024 to October 2026. Eligible participants are adults aged ≥18 years diagnosed with FNF who are indicated for internal fixation. The primary outcome is the frequency of intraoperative fluoroscopy. Secondary outcomes include the neck-shaft angle, guide wire placement quality, operative time, intraoperative blood loss, fracture healing status, the Harris Hip Score, the 36-Item Short Form Health Survey, and the Zarit Caregiver Burden Score. The sample size calculation indicated that 150 (50%) participants per group (N=300) would be needed to detect a superiority margin of 15.4 fluoroscopy images with 80% power and a 1-sided α of .025, accounting for a 15% dropout rate. All patients will undergo 12 months of follow-up. Data analysis will compare groups using 1-sided t tests and Mann-Whitney U tests, supplemented by linear mixed-effects models with study site as a random effect. Results The study was funded in May 2024 and received initial ethics approval from the institutional review board. Patient enrollment commenced in June 2024 and is projected to be completed by October 2026, with a target sample size of 300 participants. The final 12-month follow-up is expected to be completed by October 2027. As of manuscript submission, recruitment is ongoing, and no data analysis has been performed. Conclusions Successful completion of this study may introduce a new strategy for the management of FNF and help establish a standardized protocol for the use of navigation systems, potentially enhancing clinical outcomes and reducing complication rates. Trial Registration ClinicalTrials.gov NCT06713018; https://clinicaltrials.gov/study/NCT06713018 International Registered Report Identifier (IRRID) DERR1-10.2196/88180

OBJECTIVE:Double plate (DP) fixation does not significantly improve outcomes compared to lateral locking plate (LLP-only) fixation for distal femur fractures (DFFs). We hypothesize this is due to the absence of clear indications for the application of these two fixation methods. This study aims to clarify the impact of metaphyseal defect size on the outcomes of these two treatments, in order to optimize surgical efficacy and minimize complications. METHODS:We screened patients with distal femoral fractures treated with lateral locking plate or dual plate fixation at our hospital between January 2018 and June 2023 retrospectively. Information such as demographic data, fracture classification, operation details, metaphyseal bone defect size, pre-nd post-operative imaging data, and other medical records were compiled. Additionally, patients' recovery status was follow-up, including evaluation of knee joint function (Lysholm score), range of motion (ROM), and EQ-5D-3L health score. We used diverse statistical methods for further analysis, such as t-test, chi-square test, Pearson correlation coefficients, and binary logistic regression analysis. RESULTS:According to the specified criteria, 55 distal femur fracture cases were ultimately included, with 38 cases in the LLP-only group and 17 cases in the DP fixation group. In terms of surgical and follow-up information, there were no statistical differences in healing status, but there were statistically significant differences in average blood loss (p = 0.013), metaphyseal bone defect size (p < 0.001), Lysholm score (p = 0.003), and EQ-5D score (p = 0.010). Notably, compared to other parameters, the size of the fracture defect exhibited the highest correlation (0.69) with healing outcomes. In logistic regression analysis, the defect size (OR 1.052, 95% CI 1.008-1.098, p = 0.021) was independently associated with the healing outcome. Upon further analysis, non-healing cases in the LLP-only group were predominantly associated with A3, C2, and C3 type fractures, with 83.3% of these patients presenting metaphyseal defects exceeding 15 mm. CONCLUSIONS:We carried out a comparative evaluation of LLP-only versus DP fixation in addressing DFFs. Our research outcomes revealed that LLP-only fixation yielded notably suboptimal results compared to DP fixation, especially in intricate fractures accompanied by defects, such as those classified under types A3, C2, and C3. Furthermore, the more significant the defect, the less effective the fixation of LLP-only will be. This observation underscores the pivotal role of the scope of metaphysical damage in determining the most suitable internal fixation techniques for DFFs.

BACKGROUND: Peripheral nerve injuries compromise sensory and motor functions, severely affecting patients' quality of life. Early lipid peroxidation drives oxidative stress, disrupting the regenerative microenvironment. Hyaluronic acid (HA), an essential extracellular matrix component, shows promise in mitigating oxidative damage and fostering repair. METHODS: In a rat sciatic nerve crush model, HA hydrogel was applied to enhance retention at the injury site. Transcriptomic analysis at 24 hours postinjury identified key pathways. In vitro assays examined HA's protective effects on Schwann cells against lipid peroxidation and oxidative stress. In vivo, HA hydrogel was administered immediately (0 hour) postcrush, followed by 4-methylumbelliferonee induced inhibition of endogenous HA synthesis and exogenous HA supplementation to clarify HA's role. RESULTS: HA treatment reduced early lipid peroxidation, upregulated glutathione metabolism, and stimulated extracellular matrix receptor interactions, notably elevating CD44 expression. In vitro, HA lowered oxidative stress and maintained Schwann cell viability. In vivo, early HA intervention mitigated muscle atrophy, preserved myelin sheaths, and improved Sciatic Functional Index scores compared to delayed or untreated controls. Inhibiting endogenous HA synthesis impaired recovery, which was partially reversed by exogenous HA. CONCLUSIONS: Early HA intervention modulates lipid peroxidation and oxidative stress via the HA/CD44 axis, establishing a supportive microenvironment for peripheral nerve regeneration and functional recovery. These findings underscore the potential of HA-based strategies to curb early lipid peroxidation, thereby expediting nerve repair and accelerating regeneration.

Objective:To evaluate the effectiveness of Poster Fusion Cage combined with xenogeneic bone graft augmentation for bone defect management in distal radius fractures. Methods:A retrospective analysis was conducted on 20 patients with bone defects complicating distal radius fractures who met the selection criteria and were treated between June 2022 and June 2024. The cohort comprised 2 males and 18 females, aged 54-87 years (mean, 63.3 years). Etiologies included falls in 17 cases, traffic accidents in 2 cases, and crush injury in 1 case. According to AO classification, there were 5 cases of type A, 8 cases of type B, and 7 cases of type C. The interval from injury to operation ranged from 2 to 10 days (mean, 5.8 days). All patients underwent volar plate fixation augmented with Poster Fusion Cage and demineralized xenogeneic bone matrix grafting. The operation time, intraoperative blood loss, fracture healing time, and postoperative complications were recorded. Radiographic parameters, including radial height, volar tilt, and ulnar deviation, were measured on standardized X-ray films obtained immediately postoperatively and at last follow-up, and whether secondary reduction loss occurred was judged. At last follow-up, wrist range of motion (extension, flexion, radial deviation, ulnar deviation, pronation, and supination) and grip strength (expressed as a percentage of the contralateral side) were measured. Wrist function was assessed using the Disabilities of the Arm, Shoulder, and Hand (DASH) score and Patient-Rated Wrist Evaluation (PRWE) score. Results:The operation time was 70-200 minutes (mean, 116.4 minutes), and the intraoperative blood loss was 10-80 mL (mean, 36.5 mL). All surgical incisions healed by first intention, with no neurovascular complications documented. All patients were followed up 9-12 months (mean, 11.6 months). All fractures healed normally, with a healing time of 8-14 weeks (mean, 9.95 weeks). No significant difference was observed in radial height, volar tilt, or ulnar deviation between immediate postoperatively and last follow-up ( P>0.05). All fractures achieved satisfactory reduction, with no secondary loss of reduction or implant failure occurring during follow-up. At last follow-up, the range of motion of the affected wrist joint was 60°-65° (mean, 62.5°) in extension, 67°-75° (mean, 71.1°) in flexion, 18°-23° (mean, 20.4°) in radial deviation, 28°-33° (mean, 30.1°) in ulnar deviation, 69°-80° (mean, 74.7°) in pronation, and 69°-82° (mean, 75.6°) in supination. Grip strength recovered to 75%-85% (mean, 80%) of the contralateral side. Functional scores showed a DASH score of 5-15 (mean, 9.4) and PRWE score of 8.0-12.5 (mean, 10.2). Conclusion:The combination of Poster Fusion Cage and xenogeneic bone graft augmentation provides a safe and effective treatment for bone defects in distal radius fractures.

PURPOSE:To compare the clinical outcomes of structural support fixation vs. conventional fixation for depressed tibial plateau fractures (TPFs). METHODS:A retrospective analysis was conducted on patients who underwent surgical treatment for depressed TPFs at our hospital between November 2019 and September 2023. Forty-six patients with TPFs who had surgical indications were included. Based on the surgical procedures, patients were categorized into the structural support group receiving locking plate + cage fixation, and the conventional group receiving locking plate + granular bone grafting. The following parameters were evaluated and compared, including operative time, blood loss, time to full weight-bearing, fracture healing time, loss of tibial plateau height, quality of fracture reduction and alignment, hospital for special surgery knee score, and Western Ontario and McMaster Universities Osteoarthritis Index score. Intergroup differences were analyzed using independent-sample t-tests or the rank-sum test. RESULTS:A total of 46 eligible patients completed the follow-up (20 in the structural support group, 26 in the conventional group). No significant differences were observed between the 2 groups in the mean age, sex, body mass index, injury mechanism, or time from injury to surgery (p = 0.276, 0.860, 0.615, 0.160, 0.065, respectively). The mean operative time was 120.7 min in the structural support group and 164.2 min in the conventional group, with the mean blood loss of 120.0 mL and 168.5 mL, respectively. Neither operative time nor blood loss showed significant differences (p = 0.067 and p = 0.309). The mean follow-up duration was 20.2 months (structural support group) and 20.4 months (conventional group), with no significant difference (p = 0.987). At the final follow-up, the structural support group exhibited significantly less secondary step-off compared to the conventional group (0.3 mm vs. 0.7 mm, p < 0.001). While hospital for special surgery functional scores showed no significant difference (94.1 vs. 88.1, p = 0.066), the structural support group had significantly better Western Ontario and McMaster Universities Osteoarthritis Index scores (1.4 vs. 6.3, p = 0.001), with superior outcomes in pain, stiffness, and functional difficulty subscales (p = 0.009, 0.004, 0.003, respectively). No adverse events (e.g., infection, nonunion, or refracture) were found in both groups. CONCLUSION:Compared to conventional fixation, locking plate combined with cage effectively reduces secondary step-off in depressed TPFs and significantly improves pain relief and knee function.

ABSTRACT Background and Objective Customized implants could improve the capture of fracture fragments for strengthened stability of tibial plateau fractures (TPFs) fixation. This study aimed to validate the feasibility of customized implants through optimized manufacturing within a clinically acceptable timeframe and evaluate the mechanical strength of customized internal implants through finite element analysis. Methods A retrospective was conducted. From May 1, 2023, to June 1, 2023, 10 patients with TPFs were treated at our hospital using various new internal fixation systems combined with customized technology. The indicators of patients characteristics, operation, and follow‐up were collected, such as the cause of trauma, fresh or old, fracture classification, blood loss, Lysholm score, EQ‐5D‐3L score, and so on. Additionally, we created a Schatzker IV TPF model with two separated fragments in the medial to compare the biomechanical strength and directional deformation between standard medial dual plates (MDPs) and medial customized plate (MCP). Results The study found that the entire process of implant fabrication can be completed within a clinically acceptable timeframe of 3–4 days. We designed specific types of plates for different types of fractures, such as semi‐circumferential plates for lateral TPFs, γ‐type plates for medial TPFs, and pistol‐type and wing‐type plates for posterior TPFs. Follow‐up analysis showed operative times of 1.37 ± 0.58 h, intraoperative blood loss of 260 ± 179.20 mL, and favorable functional outcomes: Lysholm score 88.6 ± 4.93, knee ROM 103.5° ± 11.56°, and EQ‐5D‐3L score 0.87 ± 0.47. Additionally, the γ‐type plate showed comparable strength to the MDPs system via finite element analysis and demonstrated a more vital ability to resist the separation of fracture fragments, with the maximum displacement of MDPs (0.61878 mm) 2.4 times higher than that of MCP (0.26124 mm). Conclusions Using customized internal fixation systems provided solutions to challenges of complex fractures, within a clinically acceptable timeframe of 3–4 days. Notably, the study showed that the strength of customized internal fixation systems of γ‐shaped plate was comparable to that of conventional implants. This innovative approach offered a new avenue for managing TPFs and even complex limb fractures.

Background Age-related changes in the medial column (MC) of the proximal humerus have a major impact on fracture management; however, the changes in the morphological features remain unclear. This study aimed to investigate the age-related changes in the morphological features of MC and present the morphological grading. Methods One hundred computed tomography (CT) images of the proximal humerus of 100 individuals (19–95 years) were retrospectively obtained. The individuals were categorized into five age groups to quantify the differences among different ages; the youngest group (18–44 years) served as the baseline group. Parameters of the morphological features were measured on CT images with multiplanar reconstruction based on an explicit definition of MC, including length, thickness, width, oblique thickness (D SM ), humeral head diameter (D HM ), and ratio (R SM ) of D SM to D HM . The morphological grading of MC was presented based on the value of R SM deviating different standard deviations (SD) from the mean value in the baseline group. Results Significant negative correlations were observed between age and the morphological parameters of MC (r ranged from −0.875 to −0.926; all P < 0.05), excluding D HM ( r = 0.081, P = 0.422). Significant differences in the values of morphological feature parameters were detected among the five age groups (all P < 0.001). The highest mean values of morphological feature parameters were observed in the youngest group (18–44 years), which decreased gradually with increasing age until the lowest mean values were observed in the oldest group (≥90 years) (all P < 0.05). The morphological features of MC were categorized into three grades based on the value of R SM deviating 1.5 SD or 3 SD from the mean value in the baseline group. Conclusion Our study shows that the parameter values of morphological features of MC decreased with increasing age. The morphological features of MC could be categorized into three grades. Our findings may provide a more comprehensive insight into age-related changes in the morphological features of MC that facilitate risk stratification and optimize the management of proximal humeral fractures.

Objective: In this study, the advantages of the internal fixation configuration composed of uniplanar pedicle screws in the treatment of thoracolumbar fractures were verified by biomechanical experimental methods, which provided the basis for subsequent clinical experiments and clinical applications.Methods: A total of 24 fresh cadaveric spine specimens (T12-L2) were utilized to conduct biomechanical experiments. Two different internal fixation configurations, namely, the 6-screw configuration and the 4-screw/2-NIS (new intermediate screws) configuration, were tested using fixed-axis pedicle screws (FAPS), uniplanar pedicle screws (UPPS), and polyaxial pedicle screws (PAPS) respectively. The spine specimens were uniformly loaded with 8NM pure force couples in the directions of anteflexion, extension, left bending, right bending, left rotation, and right rotation, and the range of motion (ROM) of the T12-L1 and L1-L2 segments of the spine was measured and recorded to access biomechanical stability.Results: No structural damage such as ligament rupture or fracture occurred during all experimental tests. In the 6-screw configuration, the ROM of the specimens in the UPPS group was significantly better than that of the PAPS group but weaker than those of the FAPS group (p < 0.01). In the 4-screw/2-NIS configuration, the results were identical to the biomechanical test results for the 6-screw configuration (p < 0.01).Conclusion: Biomechanical test results show that the internal fixation configuration with UPPS can maintain the stability of the spine well, and the results are better than that of PAPS. UPPS has both the biomechanical advantages of FAPS and the superiority of easy operation of PAPS. We believe it is an optional internal fixation device for minimally invasive treatment of thoracolumbar fractures.

Background:An intertrochanteric fracture can cause ischemic necrosis in the femoral head, leading to negative effects. There are many types of implants for this fracture procedure, including metal-on-metal, metal-on-polyethylene, ceramic-on-ceramic, and ceramic-on-polyethylene, that are currently in use. The current modification is a hybrid prosthetic implant with high functional capacity compared with predecessors. This study aims to determine the procedure's efficacy in recovery, function restoration, complications, and cost-effectiveness.Methods:Our study used a total of 200 patients undergoing total hip arthroplasty and 135 patients undergoing semi-hip arthroplasty to determine the effectiveness of total hip arthroplasty and femoral head arthroplasty From May 2022 to May 2023. Using the RAOSOFT sampling technique, 132 and 101 in the observation and control group, respectively, the sample is obtained with a confidence interval of 95%, an error margin of 1%, and response interval confidence of 50%. This is a descriptive type of research that relies on a meta-analysis of the available data from PubMed, scholarly articles, and the Chinese biomedical database to gather the fundamental data needed to conduct the research. Data obtained is analyzed using SSPS and STATA and presented in tables showing a summary of the objective measured value.Result:In this study, the Harris joint score of patients in the total hip arthroplasty group was significantly higher than that of the control group, indicating that total hip arthroplasty can restore femoral head function, but still lacks absolute strength like half hip arthroplasty.Conclusions:Femoral head replacement is a complex procedure, but the efficacy in restoring the function is better. In conclusion, despite slow healing and regeneration, the efficacy of complete artificial femoral head replacement is higher in restoring function for various fractures.

BackgroundFragility fractures of the pelvis (FFPs) are osteoporotic pelvic fractures or insufficiency pelvic fractures caused by the low energy injury or stress fracture in daily livings in the elderly more than 60 years, which the incidence is increasing with the aging population in our country. FFPs result in considerable morbidity and mortality and as well as massive financial burden on the already strained health systems throughout the world.MethodsThis clinical guideline was initiated by the Trauma Orthopedic Branch of Chinese Orthopedic Association; the External Fixation and Limb Reconstruction Branch of Chinese Orthopedic Association; the National Clinical Research Center for Orthopedics, Sports Medicine & Rehabilitation; Senior Department of Orthopedics of Chinese PLA general hospital; the Third Hospital of Hebei Medical University. The grading of recommendations assessment, development and evaluation (GRADE) approach and the reporting items for practice guidelines in healthcare (RIGHT) checklist were adopted.Results22 evidence based recommendations were formulated based on 22 most concerned clinical problems among orthopedic surgeons in China.ConclusionUnderstanding these trends through this guideline will facilitate better clinical care of FFP patients by medical providers and better allocation of resources by policy makers.

Introduction: This study aims to investigate association between glycosylated hemoglobin (HbA1c) with bone mineral density (BMD) and osteoporosis-risk in postmenopausal female with type 2 diabetes mellitus (T2DM). Methodology: HbA1c values, BMD of L3 vertebra and basic clinical data of 152 postmenopausal females with T2DM and 326 postmenopausal females without T2DM were retrospectively analyzed. The propensity score matching was used to match the T2DM and the non-T2DM group at a ratio of 1:1. Restricted cubic spline (RCS) analysis and piecewise linear regression were used to evaluate the relationship between HbA1c and BMD. Univariable and multivariable logistic regression were utilized to evaluate the effect of HbA1c on the risk of osteoporosis in matched diabetes population. Results: After matching, the BMD (66.60 (46.58, 93.23) vs. 63.50 (36.70, 83.33), P < 0.05), HbA1c value (7.50 (6.72, 8.80) vs 5.30 (5.14, 5.50), P  <  0.05) in the T2DM group were significantly higher than that of non-T2DM group. We found a nonlinear relation between HbA1c value and BMD, which showing a U-shaped curve with the cutoff value around 7.5 % (Poverall < 0.001, Pnonliearity < 0.05). The prevalence of osteoporosis in T2DM group was similar to that in controls (64.9 % vs 73.6 %, P = 0.102). Age-adjusted HbA1c value was not risk factor of osteoporosis in postmenopausal females with T2DM. Conclusion: In postmenopausal females with T2DM, high BMD and similar risk of osteoporosis were confirmed; HbA1c was a contributing factor to BMD when values exceed 7.5 %. However, HbA1c does not seem to be associated with osteoporosis risk.

OBJECTIVE:To explore clinical efficacy of Ilizarov hemilateral bone longitudinal transport technique in treating hemilateral bone defects associated with chronic osteomyelitis of lower extremity long bones.METHODS:Clinical data of 13 patients with hemilateral bone defects caused by chronic osteomyelitis of lower extremity long bones and treated by Ilizarov hemilateral bone longitudinal transport technique were retrospective analyzed, including 10 males and 3 female, aged from 14 to 55 years old;4 patients occurred femoral and 9 patients occurred tibial;10 patients were diagnosed as traumatic osteomyelitis and 3 patients as hematogenous osteomyelitis. The anatomical classification of Cierny-Mader in 13 patients was type Ⅲ. Bone and wound healing, postopertaive complication, and bony and functional results were observed by Paley evaluation standard.RESULTS:After removing external fixator, all patients were followed up from 6 to 70 months. Transporting time ranged from 54 to 158 d. And the time in external fixation ranged from 6.8 to 19.5 months. External fixation index (EFI) ranged from 1.23 to 1.6 months/cm. According to Paley's evaluation criteria, bony results were excellent in 13 patients;functional results showed excellent in 12 patients and good in 1 patient. Two patients occurred poor union on the docking sites and healed with autogenous iliac bone graft. The callus at the extended area was poorly mineralized and improved significantly when treated with low-intensity pulsed ultrasound in one patient. All patients had good wound healing without recurrence of osteomyelitis and refracture. There was no vascular and nerve injury and axial deviation in all patients and they were satisfied with the appearance and function of lower limbs. The range of motion of knee and ankle joint before operation was 120 ° to 150 ° and 35 °to 80 ° respectively, and at the latest follow-up was 110 ° to 140 ° and 30 ° to 75 ° .CONCLUSION:Ilizarov hemilateral bone longitudinal transport technique is effective in treating infective hemilateral bone defects of lower extremity long bones, which could not only simplify architecture of external fixation, but also reduce the number of fixation pins, shorten the time in external fixator and decrease the incidence of pin tract infection. However, this technique is highly demanding, and the growth of callus in extended region and healing of bone apposition should be noticed.

Position and preoperative preparation, incision with body surface projection, surgical approach:

Objective: To observe the immediate effect of small-angle Tui-Pushing and An-Pressing anti-rotation bone-setting manipulation in improving the correction of braces for adolescent idiopathic scoliosis. Methods: A total of 50 cases of adolescent idiopathic scoliosis were selected and given brace correction first. The whole spine anteroposterior and lateral radiographs were taken, the Cobb angle was measured, and the visual analog scale (VAS) score of pain caused by brace wearing was recorded. After removal of the brace, small-angle Tui-Pushing and An-Pressing anti-rotation bone-setting manipulation was performed once. After treatment, the same brace was put on again to take a whole spine anteroposterior radiograph, the Cobb angle was measured, and the VAS score was recorded. The changes in Cobb angle and VAS score after manipulation were compared, and the immediate efficacy was evaluated. Results: After the manipulation, the Cobb angle was significantly smaller than that before treatment (P<0.01) and the VAS score was significantly lower than that before treatment (P<0.01). Conclusion: Small-angle Tui-Pushing and An-Pressing anti-rotation bone-setting manipulation can improve the immediate efficacy of brace in treating adolescent idiopathic scoliosis and relieve the pain caused by brace wearing at the same time.

髋部骨折是一种常见且严重的骨折类型,已成为全球的公共健康问题。我国骨质疏松患病率在2018年已经高达24%,尽管采取了预防措施,但随着我国社会老化进程的加剧,据估计到2050年我国髋部骨折的总数将稳步增加 [1-3] 。髋部骨折后1年病死率高达25%～30%,且医疗费用昂贵,此问题不容小觑,值得我们深切关注 [4-6] 。

Open reduction internal fixation technique has been generally accepted for treatment of complex humeral fractures. Traditional proximal humeral locking plate design (PHILOS) have been reported in clinical or biomechanical researches, while presently the spiral plate design has been introduced improved biomechanical behavior over conventional designs. In order to objectively realize the multi-directional biomechanical performances and minimally invasive surgery for humeral plate designs, a current conceptual finite element analysis has been conducted with identical cross-sectional features for humeral plates. The conceptual lateral, and spiral humeral plate models were constructed for virtual reduction and fixation to the multiple fractures of the humerus. Mechanical load cases including axial compression, counterclockwise torsion and anterior bending have been applied for confirming the multi-directional structural stability and implant safety in biomechanical perspective. Results revealed that the lateral humeral plate model showed lower equivalent (von-Mises) stress under counterclockwise torsion, while the spiral humeral plate model performed greater rigidity and lower equivalent (von-Mises) stress under other loading cases. Four models represented similar structural stiffness under bending load. Under the different mechanical load cases, the spiral humeral plate model revealed comparable results with acceptable multi-directional biomechanical behavior. The concept of spiral humeral plate design is worth considering in practical application in clinics. Implant safety and stability should be further investigated by evidences in future mechanical tests and clinical observations.

Background: Endosteal augmentation enhances the stability of osteoporotic proximal humeral fracture fixation, but the optimal configuration is unknown. The purpose of this study was to compare the biomechanical properties of different lengths of fibula with or without calcar screw in osteoporotic proximal humeral fracture. Methods: Three-part proximal humeral fractures with osteopenia were created on 20 pairs of fresh-frozen humeri specimens and allocated to four groups: (1) locking plate with a 6-cm fibular strut allograft, (2) locking plate with a 6-cm fibular strut allograft and additional calcar screws, (3) locking plate with a 12-cm fibular strut allograft, and (4) locking plate with a 12-cm fibular strut allograft and additional calcar screws. Specimens were loaded to simulate the force at 25. abduction. Thereafter, an axial stiffness test and a compound cyclic load to failure test were applied. Structural stiffness, number of cycles loaded to failure and relative displacement values for 5000 cycles at predetermined measurement points were recorded using a testing machine and a synchronized 3D video tracking system. Findings: In terms of initial stiffness, number of cycles loaded to failure, and relative displacement values, the groups with 12-cm fibular strut showed obvious improvement compared to the groups with 6-cm fibular strut irrespective of the influence of calcar screw implementation. Further, the groups implemented with calcar screws also showed promising biomechanical stability irrespective of fibular length. Interpretation: Lateral locking plate with longer endosteal fibular augmentation and calcar screw can significantly improve biomechanical stability for elderly proximal humeral fractures with posteromedial comminution.

To the Editor: Proximal humeral fracture (PHF) predominantly occurs in patients older than 60 years old with severe osteoporosis.[1] Although a majority of PHFs can be treated non-operatively, the complicated ones require surgical fixation.[2] In older individuals, the loss of trabecular structure and the calcar region in the proximal humeral medullary cavity makes them prone to comminuted fracture and loss of medial hinge support, leading to a high rate of implant failure and reoperation.[3] Recent studies have shown that endosteal augments incorporated into the locking plate construct might provide better medullary support and mechanical stability.[1] However, the endosteal augments used in PHF fixation are of different shapes, modes, and positions, which can lead to implant failure and reduction loss.[1,4,5] This may be because of a lack of understanding of the morphological changes that take place in the proximal humerus at different ages. Therefore, in this study, we analyzed and compared the anatomical degeneration pattern of the medullary canal between older and younger patients to have a better understanding of the medullary morphology of proximal humerus anatomically and the application of endosteal support clinically. In this retrospective study, patients with PHFs who were treated in one trauma center from January 2013 to December 2016 were reviewed. The inclusion criteria were as follows: (1) the contralateral proximal humerus was unaffected and (2) age ≥18 years. The exclusion criteria were as follows: (1) previous operative treatment on the contralateral upper limb; (2) history of illness affecting the shape and function of the contralateral upper limb, such as non-union, arthritis, tumors, and other diseases; (3) history of long-term use of steroids or other drugs affecting bone mineral density (BMD); and (4) combined metabolic osteopathy. All included patients were divided into a young (<60 years) and older group (≥60 years) based on their age, who underwent a full-length computed tomography (CT) scan of the uninjured humerus. Based on the CT images in the Digital Imaging and Communication in Medicine format, three-dimensional (3D) models of the uninjured humerus were reconstructed using the Mimics software (version 18.0; Materialise Inc., Leuven, Belgium), described as follows. After the whole humerus mask was created, the bone and the cortical bone mask were created based on the threshold (148–3071 and 662–3071 HU, respectively). Then, the medullary mask and cancellous bone mask were created using Boolean operations. The humerus models were imported into the 3-matic (V11.0, Materialise, Belgium) for analysis [Figure 1A and 1B].Figure 1: (A) The young group of patients with proximal humeral fracture. (B) The older group of patients with proximal humeral fracture. (C) The humeral head is selected and fitted to a sphere using the sphere fitting tool of the 3-matic, the semidiameter of the sphere was radius (Rs). (D) The measurement benchmarks and corresponding parameters were established for the proximal humeral medullary canal. (E) Establishment of the measurement benchmarks of the support plane and angle. The green area showed the residual dense cancellous bone in the proximal humeral head of older patients. (F) The best fitting circle of the support plane (SP) was obtained and the diameter (Ds) of the circle was measured. (G) The existing medullary system is columnar structure, which cannot achieve an anatomical matching with the medullary cavity and an effective endosteal support for older patients with proximal humeral fracture (PHF). HCA: Humerus canal axis; PH: The distance between V and AP0; PL: The distance between L and HCA; PM: The distance between M and HCA; PV: The medullary volume above the AP0; SA: Supporting angle.The measurement benchmarks were established for the medullary canal in both groups [Figure 1C–F]. Below the humeral head, the medullary canal in the 20 to 60 mm is approximately cylindrical, and the axis of the medullary cavity of the humeral shaft (humerus canal axis [HCA]) is generated using the axis fitting tool of 3-matic. The humeral head is selected and fitted to a sphere using the sphere fitting tool of the 3-matic. The center of the sphere was the center of the humeral head (Os) and the semidiameter of the sphere was Rs [Figure 1C]. The coronal datum plane (CP0) was established based on HCA and Os. Thereafter, the axial datum plane (AP0) was established with HCA as the normal line, crossing the lowest point of the humeral head on CP0. The intersection point of HCA and AP0 was taken as O. On the view of CP0, the most medial and lateral intersection points of medullary canal and AP0 are marked as medial point (M) and lateral point (L). The highest point of the medullary cavity model was defined as the apex point (V) [Figure 1D]. The interface between the medullary cavity and the humeral head and its subcapital region was defined as the support plane (SP). Then, the SP was established through the point of V and M and perpendicular to CP0. The supporting angle (SA) was defined as the angle between AP0 and SP [Figure 1E]. Finally, the section of the medullary canal at the level of the SP was calibrated, the best fitting circle of the section was obtained using the automatic fitting arc function of 3-matic software, and the diameter (Ds) of the circle was measured [Figure 1F]. Statistical analysis was performed using SPSS (version 21.0; SPSS Inc., Chicago, IL, USA). The Kolmogorov-Smirnov test was used to test whether the metric data conformed to the normal distribution. The independent sample t-test was used to compare and analyze the differences of metric data between groups conforming to the normal distribution, which was reported as arithmetic mean ± standard deviation. Count data were tested using the Chi-square test. For the outcomes of interests, such as proximal volume (PV), proximal height (PH), proximal medial distance (PM), and proximal lateral distance (PL), we used multiple regression analysis adjusting gender and humerus radius. We reported the mean value for each outcome with the predicted marginal mean from the linear regression model. Statistical significance was set at P < 0.050. Sixty patients were included in our study. Demographics characteristics in both groups showed that: (1) there was no statistical difference in terms of gender (n) (female: 22 vs. 21, P = 1.000), dominant side (n) (26 vs. 25, P = 1.000), height (1.63 ± 0.05 vs. 1.64 ± 0.07 m, P = 0.427), and weight (51.67 ± 8.72 vs. 53.02 ± 10.14 kg, P = 0.627) and (2) there was significant statistical difference (P < 0.001) in terms of age (45.8 ± 8.61 vs. 76.33 ± 6.85 years), BMD (0.96 ± 0.11 vs. 0.60 ± 0.15 g/cm2), and Neer classification of injured side (n) (2/3/4 parts: 7/13/10 vs. 2/13/15). The values of Rs (mm) were 22.31 ± 1.72 and 22.06 ± 2.06 in the young and older groups, respectively, and there was no significant statistical difference (P = 0.613). Compared with the young group, the PV (cm3) in the older group increased significantly (21.60 ± 3.03 vs. 29.40 ± 1.98 mm, P < 0.001), with significant expansion in the proximal (PH: 25.36 ± 1.08 vs. 27.38 ± 0.67 mm, P < 0.001), medial (PM: 13.14 ± 1.16 vs. 21.60 ± 3.03 mm, P < 0.001), and lateral (PL: 17.90 ± 0.95 vs. 26.02 ± 0.76 mm, P < 0.001) directions, respectively. Compared with young patients, the SA was also decreased in older ones (65.28° ± 9.89° vs. 45.02° ± 2.10°, P < 0.001). However, the SA did not show significant variation among the older patients (ranging from 41.04° to 49.24°). Multiple regression analysis results were consistent with results from the unadjusted analysis, showing a significant difference in medullary cavity morphology. Besides, there was the cancellous bone in the humeral head in the older group. Its junction with the medullary cavity was a quasi-circular facial structure with a diameter of 11.67 ± 1.50 mm. There are a few studies on the morphology of the proximal humeral medullary cavity.[6] Sprecher et al[6] reported that in osteoporotic patients, the loss of trabecular bone in the greater tubercle and the medial metaphysis was more significant compared with the loss in the subchondral region. However, these studies are based on the analysis of the two-dimensional plane of the cadaveric bone. Through the 3D reconstruction of the medullary structure, our study showed that the cylindrical-shaped medullary cavity in the younger group becomes irregular "bellbottom" shaped with bone loss in the older group. This may be the reason why a single implant fails to provide effective medullary support in older patients. Furthermore, older patients showed a significant medial offset of the medullary cavity. This characteristic change was noted, and accordingly, the endosteal support was placed as close to the medial cortex and humeral head as possible. The age-related differences in the morphology of the medullary cavity should be associated with the clinical prognosis of PHF. Clinical studies have shown that with nails- or plate-based medullary augmentation, younger patients have better clinical outcomes than older ones.[7] This is because the existing nail or augments are mostly columnar structures, which are well-matched with the medullary cavity of young patients [Figure 1G]. But in older patients, expansion of the proximal humeral medullary cavity renders the medullary cavity irregular, which does not anatomically match with the shape of the existing nails or struts [Figure 1G]. Therefore, a more effective anatomical supporting augment is needed for the treatment of older patients. In conclusion, compared with younger patients, the medullary canal of the proximal humerus expanded significantly, especially the medial offset, showing an "eggshell"-like cavity structure in older patients. Further, the residual dense cancellous bone in the humeral head could serve as an endosteal support structure with a relatively fixed support angle. It may provide anatomical references for reasonable endosteal augmentation for older patients. Funding This work was supported by grant from the National Natural Science Foundation of China (No. 81772336). Conflicts of interest None.

PURPOSE:Recurrent patellar dislocation (RPD) is the most common complication of patellar instability and the medial patellofemoral ligament (MPFL) reconstruction has become its reference treatment. Lateral patellar retinaculum (LPR) release used to be performed in association with MPFL reconstruction. The aim of this study was to investigate the added values of MPFL reconstruction plus LPR release for RPD.METHODS:After Institutional Review Board approval, RPD patients from October 2014 to April 2019 were randomly assigned into two groups (isolated MPFL reconstruction [Group I] and MPFL reconstruction plus LPR release [Group II]) and prospectively assessed until 12 months after surgery. Knee joints with flexion of 20° were scanned by a 64-row CT scanner. Congruence angle (CA), patella tilt angle (PTA), lateral patellofemoral angle (LPFA), tibial tuberosity-trochlear groove distance and patellar tilt with the quadriceps relaxed and contracted were measured. Knee function was assessed by Lysholm knee score and International Knee Documentation Committee (IKDC) score. Patients were followed up for at least 12 months.RESULTS:A total of 87 RPD patients (45 for Group I and 42 for Group II) were selected in this study. Preoperative clinical characteristics were not significantly different across groups. No serious complications were noted in either group. It was statistically insignificant between the two group patients in terms of postoperative patella associated measurements (P > 0.05 for all). The Lysholm score and IKDC score of Group I (84.5 ± 7.1 and 87.9 ± 7.2) were significantly less than that of Group II (89.7 ± 8.7 and 93.1 ± 7.7), which indicated the better knee function of Group II.CONCLUSION:LPR release plus MPFL reconstruction provides additional benefits compared with isolated MPFL reconstruction in knee function. A combination of surgical treatments for RPD should be recommended.

Objective In this study, the mechanical properties of the new spinal fixation system (NSFS) in the treatment of thoracolumbar fractures were evaluated by the finite element analysis method, so as to provide a mechanical theoretical basis for the later biomechanical experiments and clinical experiments. Methods T12-L2 bone model was constructed to simulate L1 vertebral fracture, and three models of internal fixation systems were established on the basis of universal spinal system (USS): Model A: posterior short-segment fixation including the fractured vertebra (PSFFV); Model B: short-segment pedicle screw fixation (SSPF); Model C: new spinal fixation system (NSFS). After assembling the internal fixation system and fracture model, the finite element analysis was carried out in the ANSYS Workbench 18.0 software, and the stress of nail rod system, fracture vertebral body stress, vertebral body mobility, and vertebral body displacement were recorded in the three models. Results The peak values of internal fixation stress, vertebral body stress, vertebral body maximum displacement, and vertebral body maximum activity in Model C were slightly smaller than those in Model B. Conclusions Compared with the traditional internal fixation system, the new spinal internal fixation system may have the mechanical advantage and can provide sufficient mechanical stability for thoracolumbar fractures.