Finite element analysis of a customized coronoid prosthesis for traumatic coronoid deficiency.

BACKGROUND: Traumatic coronoid deficiency with persistent elbow instability is a challenging condition. Autologous bone graft reconstruction is often associated with a range of additional clinical problems and the outcome is often unpredictable. The purpose of this study was to design a prosthetic device that can reconstruct coronoid deficiency of any height and to evaluate its mechanical properties using finite element analysis. MATERIALS AND METHODS: A customized coronoid prosthesis was designed based on image registration, automatic measurement, and computer-aided design. After pilot study and sample size calculation, image data collected from 6 patients who underwent bilateral complete upper extremity CT scans were reconstructed. The test was divided into 3 groups: coronoid intact, prosthesis and autograft. Regan-Morrey type II and autologous olecranon osteotomy models were established. The prosthesis and autogenous olecranon were assembled to the coronoid base. Stress was applied axially along the proximal humeral diaphysis and implant micromotion and contact mechanics of the humeroulnar joint were measured at 30°, 45°, 60° and 90° of joint flexion respectively. RESULTS: At all flexion angles, the maximum stress on the coronoid articular surface was significantly reduced in the prosthesis and autograft groups, with the reduction being more significant in the latter (P < .001). With increasing flexion, the maximum stress at the coronoid articular surface increased significantly after autograft reconstruction (7.2 to 68 MPa, P < .001), whereas the humeroulnar joint obtained a similar contact mechanics pattern to that of the control group after prosthetic reconstruction. As the flexion angle increased, the relative micromotion of both the prosthesis and autograft increased significantly (0.5-1.6 vs. 0.2-1.2, Pmeasure time < 0.001, Pgroups < 0.001). Contact pressure and center-of-force paths of the humeroulnar joint experience abrupt stress changes at approximately 60° of flexion. CONCLUSION: The contact stress pattern in the humeroulnar joint is similar in prosthesis and intact coronoid groups. Autograft reconstruction increases contact stresses at the articular surface and alters the joint center-of-force path. The "stress surge phenomenon" in the humeroulnar joint surface before and after 60° of flexion may be one of the mechanisms of traumatic elbow degeneration.

Morphometric feature description of the proximal ulna based on quantitative measurement: a key consideration for implant design.

PURPOSE: To perform quantitative measurements of the anatomic morphology of the proximal ulna and establish the morphologic references based on Chinese for the surgical protocol and implant design. METHODS: The computed tomography data of 156 upper extremities were involved in this study. The ulna model was reconstructed in Mimics. Ten distance and 6 angle parameters were measured by 4 independent investigators with a new quantitative measurement method. The intraclass correlation coefficient was used to evaluate the measuring reliability. Gender and side differences of measured parameters were evaluated. RESULTS: Measurements showed a mean coronoid height of 15 mm, which was 42% of ulnar height with gender-specific differences (mean 16 mm in men and 14 mm in women, P < 0.001). A mean unsupported anteromedial facet width of 8 mm was 61% of the coronoid anteromedial facet. A larger opening angle correlates to a larger olecranon-diaphysis angle (P < 0.001) and larger coronoid height (P = 0.001). A mean proximal ulna dorsal angulation of 4.7° is present in 80% of models at an average of 52 mm distal to olecranon tip. The average proximal ulna varus angulation was 16° at a mean of 74 mm distal to the olecranon tip. Morphological features between the left and right sides were highly consistent. The ICC was between 0.789 and 0.978 for inter-observer and between 0.696 and 0.997 for intra-observer reliability. CONCLUSIONS: The proximal ulna features variable morphology but minor side differences among individuals. Over half of the anteromedial facet was not supported by the proximal ulnar diaphysis, making the coronoid vulnerable to elbow trauma. Preconditioning or customized design of the ulnar plate in the clinical setting with the help of contralateral morphology may be a good choice.

Efficacy and safety of modular versus monoblock stems in revision total hip arthroplasty: a systematic review and meta-analysis.

BACKGROUND: Both modular and monoblock tapered fluted titanium (TFT) stems are increasingly being used for revision total hip arthroplasty (rTHA). However, the differences between the two designs in clinical outcomes and complications are not yet clear. Here, we intend to compare the efficacy and safety of modular versus monoblock TFT stems in rTHA. METHODS: PubMed, Embase, Web of Science, and Cochrane Library databases were searched to include studies comparing modular and monoblock implants in rTHA. Data on the survivorship of stems, postoperative hip function, and complications were extracted following inclusion criteria. Inverse variance and Mantel-Haenszel methods in Review Manager (version 5.3 from Cochrane Collaboration) were used to evaluate differences between the two groups. RESULTS: Ten studies with a total of 2188 hips (1430 modular and 758 monoblock stems) were finally included. The main reason for the revision was aseptic loosening. Paprosky type III was the most common type in both groups. Both stems showed similar re-revision rates (modular vs monoblock: 10.3% vs 9.5%, P = 0.80) and Harris Hip Scores (WMD = 0.43, P = 0.46) for hip function. The intraoperative fracture rate was 11.6% and 5.0% (P = 0.0004) for modular and monoblock stems, respectively. The rate of subsidence > 10 mm was significantly higher in the monoblock group (4.5% vs 1.0%, P = 0.003). The application of extended trochanteric osteotomy was more popular in monoblock stems (22.7% vs 17.5%, P = 0.003). The incidence of postoperative complications such as periprosthetic femoral fracture and dislocation was similar between both stems. CONCLUSIONS: No significant difference was found between modular and monoblock tapered stems as regards postoperative hip function, re-revision rates, and complications. Severe subsidence was more frequent in monoblock stems while modular ones were at higher risk of intraoperative fracture. LEVEL OF EVIDENCE: Level III, systematic review of randomized control and non-randomized studies. TRIAL REGISTRATION: We registered our study in the international prospective register of systematic reviews (PROSPERO) (CRD42020213642).

Efficacy and safety of continuous passive motion and physical therapy in recovery from knee arthroplasty: a systematic review and meta-analysis.

BACKGROUND: Continuous passive motion (CPM) is commonly used as a postoperative rehabilitation treatment, along with physical therapy, for postoperative knee rehabilitation. However, the comparison between the two in terms of efficacy in postoperative knee replacement recovery is unclear. PURPOSE: To compare efficacy and safety of combined CPM versus physical therapy alone in postoperative rehabilitation after knee arthroplasty. METHODS: PubMed, Embase, and Web of Science databases were used to retrieve and access clinical studies on the efficacy of CPM compared with physical therapy. Review Manager software was used for study publication bias assessment and data analysis based on inclusion criteria. RESULTS: A total of 6 articles covering 557 patients were included in the study. In terms of range of motion (ROM), passive knee flexion was similar between CPM and physical therapy (PT) (WMD, - 0.17; 95% CI, - 0.98-0.64; p = 0.68). At long-term follow-up, passive knee extension was similar between CPM and physical therapy (PT) (WMD, - 0.28; 95% CI, - 1.47 to - 0.92; I2 = 65%, p =0.65). In addition, CPM generates significantly higher in length of stay (WMD, 0.50; 95% CI, - 0.31 to 0.69; I2 = 3%, p < 0.001). CPM generates significantly higher treatment costs and incurs more care costs relative to physical therapy. CONCLUSION: Compared to PT, combined with CPM failed to significantly improve ROM of the knees and patient's satisfaction. In addition, CPM treatment significantly increased the cost of hospitalization.

Head-to-head comparison of [68Ga]Ga-FAPI PET and [18F]FDG PET in the detection of bone and lymph node metastasis in various cancers: A systematic review and meta-analysis.

PURPOSE: The aim of our meta-analysis and systematic review was to contrast the positivity rates of [68Ga]Ga-FAPI PET and [18F]FDG PET in detecting bone and lymph node metastases across diverse cancer types. METHODS: We conducted a comprehensive search for eligible articles up until August 2023, utilizing databases including PubMed, Embase, and Web of Science. Studies focusing on the positivity rate of [68Ga]Ga-FAPI PET vs. [18F]FDG PET for bone and lymph metastasis were included. Using random-effect model, the positivity rate for [68Ga]Ga-FAPI PET and [18F]FDG PET were generated. In order to gauge the heterogeneity among aggregated studies, we utilized the I2 statistic. Additionally, we applied the Quality Assessment of Diagnostic Performance Studies (QUADAS-2) methodology to evaluate the caliber of the studies encompassed in our analysis. RESULTS: A total of 430 publications were initially identified in the search. Eventually, 25 studies, involving 779 patients, met the inclusion criteria. In terms of bone metastasis, the findings indicate no statistically significant difference between the use of [68Ga]Ga-FAPI PET and [18F]FDG PET (P = 0.34). However, concerning lymph node metastasis, the results demonstrate significant difference between the two imaging agents (P = 0.04). CONCLUSIONS: This systematic review suggests that [68Ga]Ga-FAPI PET appears to outperform [18F]FDG PET in detecting lymph node metastases. However, when it comes to bone metastasis, no statistically significant difference was observed. It is crucial to acknowledge that the insights concerning bone metastasis stem from studies with comparatively modest sample sizes. Consequently, there is a pressing demand for further, expansive prospective studies in this field.

Finite element analysis of three internal fixations for the posteromedial split fracture fragment in tibial plateau fractures.

Posteromedial tibial plateau fracture is one of the most challenging traumatic fractures. We aimed to compare and explain the biomechanical advantages and disadvantages of different internal fixation methods for the treatment of the posteromedial split fracture fragment in tibial plateau fractures. Finite element models of the tibial plateau fracture were constructed. Three different internal fixations were developed to treat the posteromedial split fracture fragment in tibial plateau fractures finite element models: (a) the novel anatomic locking plate fixation model, (b) the common anatomic locking plate fixation model, and (c) the reconstruction plate fixation model. We applied the same loading conditions to each model: 320 N axial compression. Under the same condition, the von Mises stress (VMS) and displacement distribution of the three internal fixations and tibia plateau were studied. The stress values of the novel anatomic locking plate are lower than the common anatomic locking plate and the reconstruction plate. Additionally, the novel anatomic locking plate fixation system exhibits smaller maximum displacement. In conclusion, our study indicated that the novel anatomic locking plate resulted in a lower stress distribution in the plate and screws, and better stability than the common anatomic locking plate and the reconstruction plate for the posteromedial split fracture fragment in tibial plateau fractures fixation under the same loading conditions. Thus, for the posteromedial split fracture fragment in tibial plateau fractures, the use of the novel anatomic locking plate internal fixation is recommended.

Biomechanical Research of Three Parallel Cannulated Compression Screws in Oblique Triangle Configuration for Fixation of Femoral Neck Unstable Fractures.

OBJECTIVE: Surgical treatment with internal fixation, specifically percutaneous fixation with three cannulated compression screws (CCSs), is the preferred choice for young and middle-aged patients. The mechanical advantage of the optimal spatial configuration with three screws provides maximum dispersion and cortical support. We suspect that the spatial proportion of the oblique triangle configuration (OTC) in the cross-section of the femoral neck isthmus (FNI) may significantly improve shear and fatigue resistance of the fixed structure, thereby stabilizing the internal fixation system in femoral neck fracture (FNF). This study aims to explore the mechanical features of OTC and provide a mechanical basis for its clinical application. METHODS: Twenty Sawbone femurs were prepared as Pauwels type III FNF models and divided equally into two fixation groups: OTC and inverted equilateral triangle configuration (IETC). Three 7.3 mm diameter cannulated compression screws (CCSs) were used for fixation. The specimens of FNF after screw internal fixation were subjected to static loading and cyclic loading tests, respectively, with five specimens for each test. Axial stiffness, 5 mm failure load, ultimate load, shear displacement, and frontal rotational angle of two fragments were evaluated. In the cyclic loading test, the load sizes were 700 N, 1400 N, and 2100 N, respectively, and the fracture end displacement was recorded. Results were presented as means ± SD. Data with normal distributions were compared by the Student's t test. RESULTS: In the static loading test, the axial stiffness, ultimate load, shear displacement, and frontal rotational angle of two fragments were (738.64 vs. 620.74) N/mm, (2957.61 vs. 2643.06) N, (4.67 vs. 5.39) mm, and (4.01 vs. 5.52)° (p < 0.05), respectively. Comparison between the femoral head displacement after 10,000 cycles of 700N cyclic loading and total displacement after 20,000 cycles of 700-1400N cyclic loading showed the OTC group was less than the IETC group (p < 0.05). A comparison of femoral head displacement after 10,000 cycles of 1400N and 2100N cycles and total displacement after 30,000 cycles of 700-2100N cycles showed the OTC group was less than another group, but the difference was not significant (p > 0.05). CONCLUSION: When three CCSs are inserted in parallel to fix FNF, the OTC of three screws has obvious biomechanical advantages, especially in shear resistance and early postoperative weight-bearing, which provides a mechanical basis for clinical selection of ideal spatial configuration for unstable FNF.

Case report: Self-performed orthopedic exams in telehealth treatment of a youth athlete with acute rotator cuff strain.

Background: Sports-related rotator cuff muscle injury is one of the most prevalent pathologies affecting overhead sports athletes. Since the COVID-19 pandemic and its subsequent stay-at-home protocols, physical therapy has transited into a new realm of telehealth. Current evidence regarding examining and managing RTC strain in telehealth physical therapy is minimal. Case presentation: A self-referred 14-year-old female Chinese semi-professional tennis player presented with an acute right RTC strain. The mechanism of injury involved forehand strokes with left trunk rotation. No ligamentous or labral damage was observed on Magnetic Resonance Imagining. The individualized care plan included virtual partner-assisted assessment, online instructions on therapeutic exercises, and education with psychosocial considerations. Outcome and follow-up: After a 6-week intervention, the patient demonstrated complete shoulder range of motion, full muscle strength, complete return-to-practice, 0% Quick DASH disability index, and 6/68 on the Tampa Scale for kinesiophobia. Discussion: This case report demonstrated that telehealth is an accessible and cost-effective option for youth tennis athletes with RTC strain. This unique case showed a detailed roadmap from examination to discharge of this plan of care. There are also barriers including test and measure validity, and communication difficulties to be considered. Despite the challenges, this case was a good example of telehealth being an effective, repeatable, and cost-efficient option for patients with poor healthcare access.

Potential side effects of antibacterial coatings in orthopaedic implants: A systematic review of clinical studies.

Objective: The systematic review aimed to determine the potential side effects of antibacterial coatings in orthopaedic implants. Methods: Publications were searched in the databases of Embase, PubMed, Web of Science and Cochrane Library using predetermined keywords up to 31 October 2022. Clinical studies reporting side effects of the surface or coating materials were included. Results: A total of 23 studies (20 cohort studies and three case reports) reporting the concerns about the side effects of antibacterial coatings were identified. Three types of coating materials, silver, iodine and gentamicin were included. All of studies raised the concerns regarding safety of antibacterial coatings, and the occurrence of adverse events was observed in seven studies. The main side effect of silver coatings was the development of argyria. For iodine coatings, only one anaphylactic case was reported as an adverse event. No systemic or other general side effects were reported for gentamicin. Conclusion: Clinical studies on the side effects of antibacterial coatings were limited. Based on the available outcomes, the most reported side effects of antibacterial coatings in clinical use were argyria with silver coatings. However, researchers should always pay attention to the potential side effects of antibacterial materials, such as systematic or local toxicity and allergy.

The Global Research Status and Trends in Ice and Snow Sports Injuries from 1995 to 2022: A Bibliometric and Visualized Analysis.

OBJECTIVE: The aim of the present study is to focus on the most popular winter sports programs, and to investigate the global research status and trends in sports-related injuries. METHODS: The Web of Science (WoS) Core Collection database was chosen as original data and used for extracting publications on ice and snow sports injuries on 18 February 2022. Articles published in English between 1995 to 2022 were selected for this study. RESULTS: Finally, for the topic search, a sum of 1605 articles were extracted and used for further analysis. The country and journal ranked first-in terms of total number, total citations and the highest H-index of publications-were the USA and American Journal of Sports Medicine, respectively. The affiliation with the most cited publications was the Norwegian School of Sport Sciences. The most influential first author with the most citations (2537 times), the greatest average citations per article (65.05 times) and the highest H-index (26) was Bahr R. Articles were divided into five main clusters based on keyword analysis: injuries study, head and neck damage study, risk study, therapy study and epidemiology study. Studies related to epidemiology and brain damage in ice and snow sports will continue to be research hot topics. CONCLUSIONS: In conclusion, our study indicates that the ice and snow sports injuries research domain is more prevalent in North America and Europe. This study contributes to a comprehensive understanding of ice and snow sports injuries and provides hotspot directions.

Evaluating the biomechanical performance of Ti6Al4V volar plates in patients with distal radius fractures.

Purpose: This study aimed to investigate the biomechanical performance of three Ti6Al4V volar plates with the latest designs using a finite element model. Methods: An AO type 23-A3 distal radius fracture and the models of T plate (2.4 mm LCP Volar Distal Radius Plate), V plate (2.4 mm LCP Two-Column Volar Distal Radius Plate) and π Plate (2.4 mm Volar Rim Distal Radius Plate) (all from Depuy Synthes, West Chester, PA, USA, Ti6Al4V) were built in 3D-matic software. After assembling the internal fixation and fractures, we imported these models into the finite element analysis software (ABAQUS). An axial loading of 100 N was added to the distal end of each model. The displacements of total models and implants, the principal strains and the von Mises stresses in the plates were calculated and compared to capture the biomechanical features of the three plates. Results: The T plate, V plate and π plate represented a model displacement of 0.8414 mm, 1.134 mm and 1.936 mm, respectively. The T plate was with the implant displacement of 0.7576 mm, followed by the V plate (0.8802 mm) and the π plate (1.545 mm). The T plate had the smallest principal strain of 0.23%, the V plate showed an intermediate level of 0.28%, and the π plate had a value of 0.72%. The least peak von Mises stress was observed in the V plate with 263.6MPa, and this value was 435.6 MPa and 1050 MPa in the T plate and π plate, respectively. Conclusion: The biomechanical features of three Ti6Al4V volar locking plates in an AO type 23-A3 fracture were described in our analysis. The T plate and the V plate showed similar biomechanical performance while the π plate represented worse performance than the other two plates.

Mesenchymal stem cells can improve discogenic pain in patients with intervertebral disc degeneration: a systematic review and meta-analysis.

Background: The meta-analysis aimed to estimate the efficacy of mesenchymal stem cells on lumbar discogenic pain in patients with intervertebral disc degeneration. Methods: A comprehensive literature search was conducted in the PubMed, Web of Science, Embase and Cochrane Library databases with predetermined search strategy up to 18 September 2022. The clinical studies focusing on evaluating the efficacy and safety of mesenchymal stem cells in patients with intervertebral disc degeneration were identified. The primary outcomes were changes of pain score and Oswestry Disability Index. The Newcastle-Ottawa Scale for cohort studies was used for quality assessment. Review Manager was used to conduct the statistical analysis. Pooled risk ratios were calculated based on the random effect model. Heterogeneity, subgroup, and publication bias analyses were also performed. Results: There were 2,392 studies were identified in the initial search, and 9 eligible studies with 245 patients were eventually included in this review. The Visual Analogue Scale score was significantly lower in patients after receiving mesenchymal stem cells therapy (mean difference = 41.62; 95% confidence interval 24.32 to 58.93; Heterogeneity: I2 = 98%; p < 0.01). And the pooled mean difference of Oswestry Disability Index was 22.04 from baseline to final follow-up points (95% confidence interval 8.75 to 35.33; p = 0.001; Heterogeneity: I2 = 98%; p < 0.001). The pooled reoperation proportion was 0.074 (95% confidence interval 0.009 to 0.175; Heterogeneity: I2 = 72%; p < 0.01). There were no serious related adverse events associated with the therapy. Conclusion: The findings of this meta-analysis indicated that mesenchymal stem cells therapy may be effective in relieving pain and improving Oswestry Disability Index significantly in patients with lumbar discogenic pain. Mesenchymal stem cells therapy may also be associated with a lower risk of adverse events and reoperation rates.

Does computer-assisted orthopaedics system (ADAPT system) improve outcomes of intertrochanteric hip fractures?

INTRODUCTION: Intramedullary nailing (IMN) is a general treatment for intertrochanteric hip fractures. The computer-assisted orthopaedics system (CAOS), ADAPT system (Stryker, NJ), has been developed to facilitate lag screw insertion. When compared to the conventional freehand method, the efficacy of CAOS has not been clearly clarified. Therefore, we conducted this systematic review and meta-analysis to answer: does the CAOS performed better than freehand method in IMN. MATERIALS AND METHODS: Studies published up to January 2023 were searched in the PubMed, Embase, Web of Science and Cochrane Library databases with predetermined key words. Comparative clinical studies between CAOS (ADAPT system) and freehand method were included. The primary outcomes of interest were the tip-apex-distance (TAD) and positions of lag screw. Fluoroscopy use, operation duration and intraoperative/postoperative complications were also extracted. A meta-analysis was performed for pooled analysis. RESULTS: There were seven studies with 326 fractures in CAOS group and 325 fractures in Freehand group. All studies included presented high qualities. The CAOS group showed a statistically smaller TAD than Freehand group (weighted mean difference = -3.24 mm; 95% confidence interval [CI] -5.10 to -1.37 mm; p = 0.0007) and a better lag screw position (83/92 [90.2%] VS 64/92 [69.6%]; RR = 1.3; 95% CI 1.12 to 1.51; p = 0.0007). The operative time and radiation use revealed no difference between two groups. CONCLUSIONS: The current evidence indicated that ADAPT system could help to perform a more accurate lag screw than freehand manipulation while the operative time and radiation time was not reduced as expectations on such new technique. Long-term follow-up studies are appealed.

Classification of coronoid process fractures: A pending question.

Ulna coronoid fracture is a complicated elbow injury. Comprehensive classification of coronoid fracture can assist diagnosis, guide treatment, and improve prognosis. Existing coronoid fracture classifications are insufficient to interpret all fracture patterns. The coronoid fracture classification is associated with elbow-specific trauma patterns. Coronoid fractures are often associated with other elbow injuries, commonly with radial head fractures, which makes the clinical strategies inconsistent and prognosis poor. The current fracture classifications do not contain information about combined injuries. Preservation of ulnohumeral joint contact after trauma is critical to elbow mechanical and kinematic stability. Important fracture types for treatment include terrible-triad injuries and anteromedial facet fractures. Open reduction and internal fixation of these two fractures should be conducted when marked displacement of the fragment, elbow instability under stress, and complicated associated injuries. The current surgical tactics based on classifications are still controversial.

Prophylactic tamsulosin can reduce the risk of urinary retention after surgery in male patients: A systematic review and meta-analysis.

Objective: The meta-analysis aimed to estimate the efficacy of prophylactic tamsulosin on postoperative urinary retention (POUR) in male patients. Methods: Papers were searched in the PubMed, Embase, Web of Science, and Cochrane Library databases with predetermined keywords up to March 1, 2022. The studies reporting the preventive efficacy of prophylactic tamsulosin on POUR among men were identified. Pooled risk ratios (RRs) were calculated based on the random-effects model. Meta-regression was performed to explore potential sources of heterogeneity. Results: There were 11 studies with 1,046 patients in the tamsulosin group and 1,113 patients in the control group. The risk of POUR was significantly lower in the tamsulosin group (123/1,046 [11.8%] vs. 238/1,119 [19.0%]; RR = 0.61; 95% confidence interval [CI] 0.43 to 0.87; P = 0.006; heterogeneity: I 2 = 57%; P = 0.009). Administration of tamsulosin was related to higher risk of adverse events (57/688 [8.3%] vs. 33/624 [5.3%]; RR = 1.68; 95% CI: 1.13 to 2.48; P = 0.010; heterogeneity: I 2 = 33%; P = 0.20). The level of evidence and mean age of the included patients were identified as the potential sources of heterogeneity. Conclusion: The present meta-analysis indicated that prophylactic tamsulosin helps in preventing POUR and younger patients might benefit more from this preventive regimen. Administrating tamsulosin was also associated with a possibly higher risk of adverse events.

3D Printing and Computer-Aided Design for Precision Osteotomy-Aided Modules in Bone Biomechanical Study.

Precise and shape-matching osteotomy models are determinants of the experimental homogeneity in the assessment of orthopedic biomechanical properties. At present, however, publications on detailed description of osteotomy in bone biomechanical study are scanty. The purposes of this study were to design a new method of osteotomy-aided module production for bone biomechanical study with the help of three-dimensional (3D) printing and computer-aided design (CAD) and to test the accuracy of osteotomy. Fourteen fourth-generation composite femurs were analyzed. The composite bone was scanned using computed tomography (CT) scanner and loaded in Mimics for reconstruction and, then, imported into 3-Matic software to design intertrochanteric region, distal femur, and rotation control lever models. 3D printer was used to print each component. After assembling Sawbones and osteotomy modules, a horizontal band-saw was used to create fracture models. The volume and mass of intermediate fragments were calculated and analyzed. Satisfactory osteotomies of all composite Sawbones were achieved. The mean volume and mass of intermediate fragments were 21.0 ± 1.5 mm3 and 19.0 ± 1.2 g, respectively. Range of deviation from average of volumes was -1.9 - 2.8 mm3 and most of these deviations fall within the range of -1.4 - 2.1 mm3. Range of deviation from average of mass was -2.0 - 1.6 g and most of these deviations fall within the range of -1.4 - 1.6 g. One-dimensional histogram of deviation from average shows the precise and stable osteotomy performed based on the modules accordingly. A new method of osteotomy-aided module production for bone biomechanical study with the help of 3D printing and CAD was designed and the accuracy of osteotomy was verified. This method is expected to achieve homogeneity and standardization of osteotomy in bone biomechanical study.

Triangular Mechanical Structure of the Proximal Femur.

OBJECTIVE: The mechanical high modulus structure of the proximal femur could guide clinical surgical treatment and instrument design of proximal femoral fractures. The purpose of this study is to analyze and verify the mechanical structure of the proximal femur. METHODS: A total of 375 patients with intertrochanteric fractures were imaged using computed tomography (CT) scans. Patients were grouped according to age and sex. Cortical and medullary cavity parameters (cortical thickness [CTh], cortical mean density [CM], upper-lower diameter length [ULL], and medial-lateral diameter length [MLL]) were measured at eight planes. Six proximal femoral finite element models of different sexes and ages were constructed. To verify the measurement results, Abaqus was used to implement the force load to describe the von Mises stress distribution, and the maximum von Mises stress values of each wall of the proximal femur were compared. RESULTS: The CTh values of the lower and upper walls were higher than those of the anterior and posterior walls of the femoral neck (p < 0.05). The CM values of the lower and upper walls were higher than those of the anterior and posterior walls of the subcephalic and middle femoral neck (p < 0.05). The ULL value gradually increased from the subcephalic region to the bottom (p < 0.05). The CTh and CM values of the medial and lateral walls were higher than those of the anterior and posterior walls in the femoral trochanteric region (p < 0.05). The MLL value decreased gradually from the plane 20 mm above the upper edge to that 20 mm below the vertex of the femoral lesser trochanter (p < 0.05). The von Mises stress was concentrated on the upper and lower walls of the femoral neck and on the medial and lateral walls of the femoral trochanteric region. The maximum von Mises stress values of the upper and lower walls were higher than those of the anterior and posterior walls of the femoral neck. The maximum von Mises stress values of the medial and lateral walls were higher than those of the anterior and posterior walls in the femoral trochanteric region, except for the plane 20 mm above the upper edge of the femoral lesser trochanter. CONCLUSION: The bone mass of the proximal femur presented a triangular high-modulus distribution, which bore the main stress of the proximal femur. The triangular mechanical structure provides a guideline for the surgical strategy and instrument design of the proximal femur.

Prediction of osteoporosis from proximal femoral cortical bone thickness and Hounsfield unit value with clinical significance.

Background: Utilizing dual-energy x-ray absorptiometry (DXA) to assess bone mineral density (BMD) was not routine in many clinical scenarios, leading to missed diagnoses of osteoporosis. The objective of this study is to obtain effective parameters from hip computer tomography (CT) to screen patients with osteoporosis and predict their clinical outcomes. Methods: A total of 375 patients with hip CT scans for intertrochanteric fracture were included. Among them, 56 patients possessed the data of both hip CT scans and DXA and were settled as a training group. The cortical bone thickness (CTh) and Hounsfield unit (HU) values were abstracted from 31 regions of interest (ROIs) of the proximal femur. In the training group, the correlations between these parameters and BMD were investigated, and their diagnostic efficiency of osteoporosis was assessed. Finally, 375 patients were divided into osteoporotic and nonosteoporotic groups based on the optimal cut-off values, and the clinical difference between subgroups was evaluated. Results: The CTh value of ROI 21 and the HU value of ROI 14 were moderately correlated with the hip BMD [r = 0.475 and 0.445 (p < 0.001), respectively]. The best diagnostic effect could be obtained by defining osteoporosis as CTh value < 3.19 mm in ROI 21 or HU value < 424.97 HU in ROI 14, with accuracies of 0.821 and 0.883, sensitivities of 84% and 76%, and specificities of 71% and 87%, respectively. The clinical outcome of the nonosteoporotic group was better than that of the osteoporotic group regardless of the division criteria. Conclusion: The CTh and HU values of specific cortex sites in the proximal femur were positively correlated with BMD of DXA at the hip. Thresholds for osteoporosis based on CTh and HU values could be utilized to screen osteoporosis and predict clinical outcomes.

Evaluation of Ankle Fractures in 228 Patients From a Single Center Using Three-Dimensional Computed Tomography Mapping.

Purpose: The ankle joint has a complex anatomy structure with many causative factors and various injury mechanisms, and the clinical presentation of ankle fractures is diverse. This study aimed to analyze the characteristics of ankle fractures by applicating three-dimensional fracture line mapping technique. Methods: A retrospective study was conducted on 228 patients with ankle fractures. Three-dimensional reconstruction was performed by CT images and the fracture reconstruction model was superimposed onto a standard model of the tibiofibula for fracture line drawing. Then the fracture lines were converted into a three-dimensional coordinate point data set. And the fracture line maps as well as the fracture line heat maps were generated in 3-Matic software and Unigraphics NX software, respectively. Results: The dense area of the fibular fracture lines was located above the tibiofibular joint ligament and wrapped obliquely around the distal fibula from the anterior edge of the fibular neck. The fibular fracture line could be divided into three categories according to the degree of denseness. The dense area of the tibial fracture line is located within the anterior tibial fornix, the anterolateral corner, and the fibular notch. The tibial fracture lines can be classified into four categories according to the density of the fracture lines. The combined medial malleolus + posterior malleolar fracture line situation was found to be not encompassed by the existing AO and Lauge-Hansen (LH) classification systems according to this classification. Conclusion: The 3D fracture line mapping technique can better reflect the distribution of ankle fracture lines and could help to establish a new ankle fracture typing system in the future.