OBJECTIVES: This study aims to analyze the biomechanics of three kinds of rigid internal fixation methods for condylar head fractures. METHODS: A three dimensional finite element model of the normal mandible was constructed. It was then used to prepare condylar head fracture finite element model and three kinds of rigid internal fixation finite element model (unilateral tension screw, bilateral tension screw, tension screw+titanium plate). The mechanical characteristics and changes of the mandible condyle under the same mechanical conditions were compared among the three different rigid internal fixation methods. RESULTS: The maximum equivalent stress and displacement of the non-free end of condyle under the rigid internal fixation method of unilateral tension screw were 71.03 MPa and 4.72 mm, respectively. The maximum equivalent stress and displacement of the free end of condyle were 78.45 MPa and 4.50 mm, respectively. The maximum stress of fracture suture was 3.27 MPa. The maximum equivalent stress and displacement of the non-free end of condyle under the rigid internal fixation method of bilateral tension screw were 70.52 MPa and 4.00 mm, respectively. The maximum equivalent stress and displacement of the free end of condyle were 72.49 MPa and 3.85 mm, respectively. The maximum stress of fracture suture was 2.33 MPa. The maximum equivalent stress and maximum displacement of the non-free end of condyle under the rigid internal fixation method of tension screw+titanium plate were 67.26 MPa and 2.66 mm, respectively. The maximum equivalent stress and maximum displacement of the free end of condyle were 69.66 MPa and 2.50 mm, respectively. The maximum stress of fracture suture was 2.18 MPa. CONCLUSIONS The tension screw+titanium plate rigid internal fixation method is the most conducive to biomechanical distribution for condylar head fractures.
Fracture Fixation, Internal/instrumentation* ; Mandibular Condyle/surgery* ; Biomechanical Phenomena ; Bone Screws ; Finite Element Analysis ; Humans ; Mandibular Fractures/surgery* ; Bone Plates ; Titanium ; Stress, Mechanical

This article aims to compare and analyze the biomechanical differences between wing-shaped titanium plates and traditional titanium plates in fixing acetabular anterior column and posterior hemi-transverse (ACPHT) fracture under multiple working conditions using the finite element method. Firstly, four sets of internal fixation models for acetabular ACPHT fractures were established, and the hip joint stress under standing, sitting, forward extension, and abduction conditions was calculated through analysis software. Then, the stress of screws and titanium plates, as well as the stress and displacement of the fracture end face, were analyzed. Research has found that when using wing-shaped titanium plates to fix acetabular ACPHT fractures, the peak stress of screws decreases under all working conditions, while the peak stress of wing-shaped titanium plates decreases under standing and sitting conditions and increases under forward and outward extension conditions. The relative displacement and mean stress of the fracture end face decrease under all working conditions, but the values are higher under forward and outward extension conditions. Wing-shaped titanium plates can reduce the probability of screw fatigue failure when fixing acetabular ACPHT fractures and can bear greater loads under forward and outward extension conditions, improving the mechanical stability of the pelvis. Moreover, the stress on the fracture end surface is more conducive to stimulating fracture healing and promoting bone tissue growth. However, premature forward and outward extension rehabilitation exercises should not be performed.
Titanium ; Bone Plates ; Humans ; Acetabulum/surgery* ; Fracture Fixation, Internal/methods* ; Biomechanical Phenomena ; Finite Element Analysis ; Bone Screws ; Fractures, Bone/surgery* ; Stress, Mechanical ; Working Conditions

OBJECTIVE: To analyze the effectiveness of three internal fixation methods, namely hollow screw combined with Kirschner wire tension band, hollow screw combined with anchor nail, and modified 1/3 tubular steel plate, in the treatment of avulsion fracture of tibial tubercle (AFTT) in adolescents. METHODS: Between January 2018 and September 2023, 19 adolescent AFTT patients who met the selection criteria were admitted. According to different internal fixation methods, patients were divided into group A (8 cases, hollow screw combined with Kirschner wire tension band), group B (6 cases, hollow screw combined with anchor nail), and group C (5 cases, modified 1/3 tubular steel plate). There was no significant difference in the baseline data of age, gender, side, cause of injury, Ogden classification, and time from injury to operation among the three groups ( P>0.05). The range of motion (ROM), weight-bearing time, normal activity time of knee joint, and the hospital for special surgery (HSS) score at last follow-up were recorded and compared among the three groups. Recorded whether the fracture was displaced, whether the fracture line was blurred at 1 month after operation, whether there was epiphyseal dysplasia, and whether there was incision infection and other complications. RESULTS: There was no significant difference in hospital stay between the groups ( P>0.05). All patients were followed up 10-24 months, with an average of 14.3 months; there was no significant difference between the groups ( P>0.05). All the incisions healed well without soft tissue irritation or fracture nonunion, and no limb shortening deformity or epiphyseal dysplasia was found during follow-up. At 1 month after operation, the knee joint ROM and hospitalization expenses in group A were better than those in groups B and C, the fracture healing time, knee joint weight-bearing time, and normal activity time of knee joint were better than those in group C, and the hospitalization expenses in group C were better than those in group B, with significant differences ( P<0.05); there was no significant difference in the other indicators between the groups ( P>0.05). In group A, the fracture line was blurred 1 month postoperatively, the fracture ends were in close contact, and there was no fracture displacement; in groups B and C, the fracture line was clear in 2 cases, and 1 case in group C had slight fracture displacement; except for 1 case in group B, there was no fracture split in the other two groups. There was no significant difference in the incidences of blur of fracture line, fracture displacement, and intraoperative bone split between the groups at 1 month after operation ( P>0.05). At last follow-up, the HSS scores of knee joints in the three groups were excellent and good, and there was no significant difference between the groups ( P>0.05). CONCLUSION Hollow screw combined with Kirschner wire tension band technique is effective in treating adolescent AFTT, which has the advantages of stabilizing fracture, accelerating fracture healing and rehabilitation, early feasible knee joint functional exercise, and reducing hospitalization expenses.
Humans ; Tibial Fractures/surgery* ; Adolescent ; Male ; Fracture Fixation, Internal/instrumentation* ; Female ; Fractures, Avulsion/surgery* ; Bone Wires ; Bone Screws ; Bone Plates ; Treatment Outcome ; Range of Motion, Articular ; Bone Nails ; Weight-Bearing ; Fracture Healing

OBJECTIVE: To investigate the effectiveness of digital three-dimensional (3D) printing osteotomy guide plate assisted total knee arthroplasty (TKA) in treatment of knee osteoarthritis (KOA) patients with femoral internal implants. METHODS: The clinical data of 55 KOA patients who met the selection criteria between July 2021 and October 2023 were retrospectively analyzed. Among them, 26 cases combined with femoral implants were treated with digital 3D printing osteotomy guide plate assisted TKA (guide plate group), and 29 cases were treated with conventional TKA (control group). There was no significant difference in gender, age, body mass index, side, Kellgren-Lawrence classification, preoperative visual analogue scale (VAS) score, Hospital for Special Surgery (HSS) knee score, knee range of motion, and other baseline data between the two groups ( P>0.05). The operation time, intraoperative blood loss, incision length, postoperative first ambulation time, surgical complications; VAS score, knee HSS score, knee range of motion before operation, at 1 week and 3 months after operation, and at last follow-up; distal femoral lateral angle, proximal tibial medial angle, hip-knee-ankle angle and other imaging indicators at last follow-up were recorded and compared between the two groups. RESULTS: The operation time, incision length, intraoperative blood loss, and postoperative first ambulation time in the guide plate group were significantly lower than those in the control group ( P<0.05). In the control group, there were 1 case of incision rupture and bleeding and 1 case of lower limb intermuscular venous thrombosis, which was cured after symptomatic treatment. There was no complication such as neurovascular injury, incision infection, or knee prosthesis loosening in both groups. Patients in both groups were followed up 12-26 months, with an average of 16.25 months. The VAS score, HSS score, and knee range of motion improved at each time point after operation in both groups, and further improved with time after operation, the differences were significant ( P<0.05). The above indicators in the guide plate group were significantly better than those in the control group at 1 week and 3 months after operation ( P<0.05), and there was no significant difference between the two groups at last follow-up ( P>0.05). At last follow-up, the distal femoral lateral angle, the proximal tibial medial angle, and the hip-knee-ankle angle in the guide plate group were significantly better than those in the control group ( P<0.05). CONCLUSION The application of digital 3D printing osteotomy guide plate assisted TKA in the treatment of KOA patients with femoral implants can simplify the surgical procedures, overcome limitations of conventional osteotomy guides, reduce surgical trauma, achieve individualized and precise osteotomy, and effectively restore lower limb alignment and knee joint function.
Humans ; Arthroplasty, Replacement, Knee/instrumentation* ; Osteoarthritis, Knee/surgery* ; Osteotomy/instrumentation* ; Male ; Retrospective Studies ; Female ; Printing, Three-Dimensional ; Femur/surgery* ; Middle Aged ; Bone Plates ; Range of Motion, Articular ; Aged ; Treatment Outcome ; Surgery, Computer-Assisted/methods* ; Knee Prosthesis ; Knee Joint/surgery* ; Operative Time

OBJECTIVE: To evaluate the safety and effectiveness of anterior cervical discectomy and fusion (ACDF) by using zero-profile anchored cage (ZAC) in treatment of consecutive three-level cervical spondylosis, by comparing with plate-cage construct (PCC). METHODS: A clinical data of 65 patients with cervical spondylosis admitted between January 2020 and December 2022 and met the selection criteria was retrospectively analyzed. During consecutive three-level ACDF, 35 patients were fixed with ZAC (ZAC group) and 30 patients with PCC (PCC group). There was no significant difference in baseline data between the two groups ( P>0.05), including gender, age, body mass index, surgical segment, preoperative Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), visual analogue scale (VAS) score, prevertebral soft tissue thickness (PSTT), cervical lordosis, and surgical segmental angle. The operation time, intraoperative blood loss, hospital stay, clinical indicators (JOA score, NDI, VAS score), and radiological indicators (cervical lordosis, surgical segmental angle, implant subsidence, surgical segment fusion, and adjacent segment degeneration), and the postoperative complications [swelling of the neck (PSTT), dysphagia] were recorded and compared between the two groups. RESULTS: Patients in both groups were followed up 24-39 months. There was no significant difference in follow-up duration between the two groups ( P>0.05). The operation time and intraoperative blood loss were lower in ZAC group than in PCC group, and the length of hospital stay was longer, but there was no significant difference ( P>0.05). At each time point after operation, both groups showed significant improvements in JOA score, VAS score, and NDI compared with preoperative scores ( P<0.05), but there was no significant difference between the two groups at each time point after operation ( P>0.05). Both groups showed an increase in PSTT at 3 days and 3, 6 months after operation compared to preoperative levels ( P<0.05), but returned to preoperative levels at last follow-up ( P>0.05). The PSTT at 3 days and 3 months after operation were significantly lower in ZAC group than in PCC group ( P<0.05), and there was no significant difference between the two groups at 6 months and at last follow-up ( P>0.05). The incidences of dysphagia at 3 days and 3 months were significantly lower in ZAC group than in PCC group ( P<0.05), while no significant difference was observed at 6 months and last follow-up between the two groups ( P>0.05). There was no postoperative complication in both groups including hoarseness, esophageal injury, cough, or hematoma. Both groups showed improvement in cervical lordosis and surgical segmental angle compared to preoperative levels, with a trend of loss during follow-up. The cervical lordosis loss and surgical segmental angle loss were significantly more in the ZAC group than in PCC group ( P<0.05). The incidence of implante subsidence was significantly higher in ZAC group than in PCC group ( P<0.05). There was no significant difference between the ZAC group and PCC group in the incidences of surgical segment fusion and adjacent segment degeneration ( P>0.05). CONCLUSION In consecutive three-level ACDF, both ZAC and PCC can achieve satisfactory effectiveness. The former can reduce the incidence of postoperative dysphagia, while the latter can better maintain cervical curvature and reduce the incidence of implant subsidence.
Humans ; Spondylosis/surgery* ; Cervical Vertebrae/surgery* ; Spinal Fusion/instrumentation* ; Male ; Female ; Retrospective Studies ; Middle Aged ; Diskectomy/instrumentation* ; Bone Plates ; Treatment Outcome ; Adult ; Aged ; Internal Fixators ; Operative Time ; Length of Stay

OBJECTIVE: To investigate the effectiveness of using 3 hollow compression screws combined with 1 screw off-axis fixation under the guidance of three-dimensional (3D) printed guide plate with mortise-tenon joint structure (mortise-tenon joint plate) for the treatment of Pauwels type Ⅲ femoral neck fractures. METHODS: A clinical data of 78 patients with Pauwels type Ⅲ femoral neck fractures, who were admitted between August 2022 and August 2023 and met the selection criteria, was retrospectively analyzed. The operations were assisted with mortise-tenon joint plates in 26 cases (mortise-tenon joint plate group) and traditional guide plates in 28 cases (traditional plate group), and without guide plates in 24 cases (control group). There was no significant difference in the baseline data of gender, age, body mass index, cause of injury, and fracture side between groups ( P>0.05). The operation time, intraoperative blood loss, frequency of intraoperative fluoroscopy, incision length, incidence of postoperative deep vein thrombosis of lower extremity, pain visual analogue scale (VAS) score at 1 week after operation, and Harris score of hip joint at 3 months after operation were recorded and compared. X-ray re-examination was taken to check the quality of fracture reduction, fracture healing, and the shortening length of the femoral neck at 3 months after operation, and the incidences of internal fixation failure and osteonecrosis of the femoral head during operation. RESULTS: Compared with the control group, the operation time, intraoperative blood loss, and frequency of intraoperative fluoroscopy reduced in the two plate groups, and the quality of fracture reduction was better, but the incision was longer, and the differences were significant ( P<0.05). The operation time and intraoperative blood loss were significantly higher in the traditional plate group than in the mortise-tenon joint plate group ( P<0.05), the incision was significantly longer ( P<0.05); and the difference in fracture reduction quality and the frequency of intraoperative fluoroscopy was not significant between two plate groups ( P>0.05). There was 1 case of deep vein thrombosis of lower extremity in the traditional plate group and 1 case in the control group, while there was no thrombosis in the mortise-tenon joint plate group. There was no significant difference in the incidence between groups ( P>0.05). All patients were followed up 12-15 months (mean, 13 months). There was no significant difference in VAS score at 1 week and Harris score at 3 months between groups ( P>0.05). Compared with the control group, the fracture healing time and the length of femoral neck shortening at 3 months after operation were significantly shorter in the two plate groups ( P<0.05). There was no significant difference between the two plate groups ( P>0.05). There was no significant difference in the incidences of non-union fractures, osteonecrosis of the femoral head, or internal fixation failure between groups ( P>0.05). CONCLUSION For Pauwels type Ⅲ femoral neck fractures, the use of 3D printed guide plate assisted reduction and fixation can shorten the fracture healing time, reduce the incidence of postoperative complications, and be more conducive to the early functional exercise of the affected limb. Compared with the traditional guide plate, the mortise-tenon joint plate can reduce the intraoperative bleeding and shorten the operation time.
Humans ; Femoral Neck Fractures/diagnostic imaging* ; Bone Plates ; Fracture Fixation, Internal/instrumentation* ; Male ; Female ; Retrospective Studies ; Middle Aged ; Bone Screws ; Adult ; Aged ; Treatment Outcome ; Printing, Three-Dimensional ; Operative Time

OBJECTIVE: To compare the effectiveness and shoulder function of reverse total shoulder arthroplasty (RTSA) and open reduction and internal fixation (ORIF) in the treatment of Neer three/four-part proximal humeral fractures in the elderly. METHODS: Randomized controlled analysis was conducted on 68 patients over 70 years old with Neer three/four-part proximal humeral fractures treated with RTSA or ORIF between January 2020 and June 2022. The patients were randomly divided into RTSA group ( n=32) and ORIF group ( n=36). There was no significant difference ( P>0.05) in the baseline data such as age, gender, body mass index, injured side, Neer classification, and preoperative Charlson comorbidity index, visual analogue scale (VAS) score, Constant shoulder score, Oxford shoulder score (OSS), and hemoglobin (Hb). The operation time, intraoperative blood loss, reduction of Hb on the 3rd day after operation, hospital stay, total cost of hospitalization, complication incidence, range of motion of shoulder joint at 2 years after operation, VAS score before operation and at 5 days and 1 month after operation, Constant shoulder score and OSS score before operation and at 2 years after operation, and imaging results during follow-up were recorded and compared between the two groups. RESULTS: Compared with the ORIF group, the RTSA group had longer operation time, less intraoperative blood loss, and higher total cost of hospitalization ( P<0.05). There was no significant difference in Hb reduction on the 3rd day after operation between the two groups ( P>0.05). The VAS scores significantly improved in both groups at 5 days and 1 month after operation ( P<0.05), but there was no significant difference between the two groups ( P>0.05). All patients were followed up 26-35 months, with an average of 31.2 months. In the RTSA group, there were 2 cases of poor healing of superficial incision and 1 case of transient nerve injury. There was no complication such as bone resorption around the prosthesis, lucent band, prosthesis loosening, or periprosthetic fracture in all patients. In the ORIF group, there was 1 case of poor healing of superficial incision, 3 cases of nonunion of fracture, 1 case of arthritis secondary to humeral head necrosis, and 1 case of bone absorption of large tuberosity, and no displacement or fracture failure of internal fixation was found in all patients. There was no significant difference in the incidence of complications [9.4% (3/32) vs 16.7% (6/36)] between the two groups [ OR (95% CI): 0.828 (0.171, 4.014), P=0.814]. In the RTSA group, 28 cases were graded 0 and 4 cases were graded 1 at 2 years after operation. Constant and OSS scores of RTSA group were significantly better than those of ORIF group ( P<0.05). The Constant score was significantly better than ORIF group in activity and strength, range of motion, lifting, abduction, and external rotation ( P<0.05), and there was no significant difference in pain, daily function, and internal rotation between the two groups ( P>0.05). The RTSA group had a significantly greater range of motion in lifting, abduction, and external rotation than ORIF group ( P<0.05), but there was no significant difference in internal rotation between the two groups ( P>0.05). CONCLUSION Application of RTSA as the initial treatment of Neer three/four-part proximal humeral fractures in the elderly can achieve better rehabilitation of joint activity and lower risk of early reoperation, and improve the quality of life of elderly fracture patients. However, the difficulty of revision and the high cost of treatment require the surgeon to pay full attention and strictly grasp the indications.
Humans ; Fracture Fixation, Internal/instrumentation* ; Male ; Female ; Shoulder Fractures/surgery* ; Arthroplasty, Replacement, Shoulder/methods* ; Aged ; Bone Plates ; Open Fracture Reduction/methods* ; Range of Motion, Articular ; Treatment Outcome ; Shoulder Joint/physiopathology* ; Aged, 80 and over ; Operative Time ; Postoperative Complications/epidemiology* ; Length of Stay

OBJECTIVE: To compare the effectiveness of posterior axillary edge approach and arthroscopic assisted reduction in the treatment of Ideberg type Ⅰ and Ⅱ glenoid fracture of the scapula. METHODS: The clinical data of 26 patients with fresh Ideberg type Ⅰ and Ⅱ scapular fractures admitted between June 2021 and September 2024 who met the selection criteria were analyzed retrospectively. The patients were divided into two groups according to different treatment methods. Ten cases in the posterior axillary edge group were fixed by open reduction plate through the posterior axillary edge approach, and 16 cases in the arthroscopy group were treated with suture anchor fixation under arthroscopy. There was no significant difference in baseline data between the two groups ( P>0.05), such as gender, age, surgical side, Ideberg type, cause of injury, time from injury to operation, rotator cuff injury, and superior labrum anterior posterior (SLAP) injury, etc. The operation time and fracture healing time were recorded and compared between the two groups, and the shoulder pain was evaluated by visual analogue scale (VAS) score at 1 week, 1 month, and 3 months after operation. At 3 and 6 months after operation, the range of motion of shoulder joint in anteflexion, abduction, external rotation, internal rotation, and backward extension was evaluated, the upper limb dysfunction was evaluated by the Disability Assessment Scale of Arm, Shoulder, and Hand (DASH), and the shoulder joint function was evaluated by the Constant-Murley score. The differences between 6 months and 3 months after operation (changes) were statistically analyzed. RESULTS: Patients in both groups were followed up 11-13 months, with an average of 12.5 months. The operation time and fracture healing time in the posterior axillary edge group were significantly shorter than those in the arthroscopy group ( P<0.05). There was no complication such as wound infection, vascular and nerve injury, loss of reduction, bone nonunion, or glenohumeral instability in both groups. At 1 week after operation, the VAS score in the posterior axillary edge group was significantly higher than that in the arthroscopy group ( P<0.05); there was no significant difference in the VAS score between the two groups at 1 and 3 months after operation ( P>0.05). At 6 months after operation, the changes of shoulder joint in anteflexion, internal rotation range of motion and DASH scores in the posterior axillary edge group were significantly lower than those in the arthroscopy group ( P<0.05), while the changes of abduction, external rotation, backward extension range of motion and Constant-Murley scores were not significantly different between the two groups ( P>0.05). CONCLUSION For Ideberg type Ⅰ and Ⅱ glenoid fracture of the scapula, the posterior axillary edge approach for internal fixation has a short operation time, fast fracture healing, and is beneficial for early functional recovery; arthroscopic assisted reduction has minimal trauma and can handle joint injuries simultaneously. Both surgical procedures are safe and effective, and individualized selection should be made based on soft tissue conditions and combined injuries.
Humans ; Arthroscopy/methods* ; Scapula/surgery* ; Male ; Female ; Retrospective Studies ; Adult ; Fracture Fixation, Internal/instrumentation* ; Fractures, Bone/surgery* ; Middle Aged ; Treatment Outcome ; Bone Plates ; Suture Anchors ; Fracture Healing ; Range of Motion, Articular ; Young Adult ; Shoulder Joint/surgery* ; Operative Time

OBJECTIVE: To compare the biomechanical properties of personalized Y-shaped plates with horizontal plates, vertical plates, and traditional Y-shaped plates in the treatment of distal humeral intra-articular fractures through finite element analysis, and to evaluate their potential for clinical application. METHODS: The study selected a 38-year-old male volunteer and obtained a three-dimensional model of the humerus by scanning his upper limbs using a 64-slice spiral CT. Four types of fracture-internal fixation models were constructed using Mimics 19.0, Geomagic Wrap 2017, Creo 6.0, and other software: horizontal plates, vertical plates, traditional Y-shaped plate, and personalized Y-shaped plate. The models were then meshed using Hypermesh 14.0 software, and material properties and boundary conditions were defined in Abaqus 6.14 software. AnyBody 7.3 software was used to simulate elbow flexion and extension movements, calculate muscle strength, joint forces, and load torques, and compare the peak stress and maximum displacement of the four fixation methods at different motion angles (10°, 30°, 50°, 70°, 90°, 110°, 130°, 150°) during elbow flexion and extension. RESULTS: Under dynamic loading during elbow flexion and extension, the personalized Y-shaped plate exhibits significant biomechanical advantages. During elbow flexion, the peak internal fixation stress of the personalized Y-shaped plate was (28.8±0.9) MPa, which was significantly lower than that of the horizontal plates, vertical plates, and traditional Y-shaped plate ( P<0.05). During elbow extension, the peak internal fixation stress of the personalized Y-shaped plate was (18.1±1.6) MPa, which was lower than those of the other three models, with significant differences when compared with horizontal plates and vertical plates ( P<0.05). Regarding the peak humeral stress, the personalized Y-shaped plate model showed mean values of (10.9±0.8) and (13.1±1.4) MPa during elbow flexion and extension, respectively, which were significantly lower than those of the other three models ( P<0.05). Displacement analysis showed that the maximum displacement of the humerus with the personalized Y-shaped plate during elbow flexion was (2.03±0.08) mm, slightly higher than that of the horizontal plates, but significantly lower than that of the vertical plates, showing significant differences ( P<0.05). During elbow extension, the maximum displacement of the humerus with the personalized Y-shaped plate was (1.93±0.13) mm, which was lower than that of the other three models, with significant differences when compared with vertical plates and traditional Y-shaped plates ( P<0.05). Stress contour analysis showed that the stress of the personalized Y-shaped plate was primarily concentrated at the bifurcation of the Y-shaped structure. Displacement contour analysis showed that the personalized Y-shaped plate effectively controlled the displacement of the distal humerus during both flexion and extension, demonstrating excellent stability. CONCLUSION The personalized Y-shaped plate demonstrates excellent biomechanical performance in the treatment of distal humeral intra-articular fractures, with lower stress and displacement, providing more stable fixation effects.
Humans ; Male ; Adult ; Healthy Volunteers ; Finite Element Analysis ; Tomography, Spiral Computed ; Models, Anatomic ; Biomechanical Phenomena ; Humeral Fractures, Distal/surgery* ; Fracture Fixation, Internal/instrumentation* ; Bone Plates ; Computer Simulation ; Precision Medicine/methods* ; Elbow Joint/surgery* ; Elbow/surgery* ; Humerus/surgery* ; Torque ; Stress, Mechanical ; Intra-Articular Fractures/surgery* ; Prosthesis Design/methods* ; Imaging, Three-Dimensional ; Range of Motion, Articular

OBJECTIVE: To investigate whether adding 1 transverse screw (TS) to the triangular parallel cannulated screw (TPCS) fixation has a mechanical stability advantage for Pauwels type Ⅲ femoral neck fractures by conducting finite element analysis on four internal fixation methods. METHODS: Based on CT data of a healthy adult male volunteer's femur, three Pauwels type Ⅲ femoral neck fracture models (Pauwels angle 70°, Pauwels angle 80°, and Pauwels angle 70° combined with bone defect) were constructed using Mimics 21.0 software and SolidWorks 2017 software. Four different internal fixation models were built at the same time, including TPCS, TPCS+TS, three cross screws (TCS), and TPCS+medial buttress plate (MBP). The mechanical stability of different models under the same load was compared by finite element analysis. RESULTS: The femoral model established in this study exhibited a maximum stress of 28.62 MPa, with relatively higher stress concentrated in the femoral neck. These findings were comparable to previous studies, indicating that the constructed femoral finite element model was correct. The maximum stress of internal fixation in finite element analysis showed that TCS was the lowest and TPCS+MBP was the highest in Pauwels angle 70° and 80° models, while TPCS+TS was the lowest and TCS was the highest in Pauwels angle 70° combined with bone defect model. The maximum displacement of internal fixation in each fracture model was located at the top of the femoral head, with TCS having the highest maximum displacement of the femur. The maximum stress of fracture surface in finite element analysis showed that TCS was the lowest and TPCS was the highest in the Pauwels angle 70° model, while TPCS+MBP was the lowest and TPCS/TCS were the highest in the Pauwels angle 80° model and the Pauwels angle 70° combined with bone defect model, respectively. The maximum displacement of fracture surfece analysis showed that TPCS+MBP was the lowest and TCS was the highest in Pauwels angle 70° and 80° models, while TPCS+TS was the lowest and TCS was the highest in Pauwels angle 70° combined with bone defect model. CONCLUSION For Pauwels type Ⅲ femoral neck fractures, the biomechanical stability of TPCS+TS was superior to that of TPCS alone and TCS, but it has not yet reached the level of TPCS+MBP.
Finite Element Analysis ; Humans ; Femoral Neck Fractures/diagnostic imaging* ; Bone Screws ; Fracture Fixation, Internal/instrumentation* ; Male ; Bone Plates ; Stress, Mechanical ; Biomechanical Phenomena ; Tomography, X-Ray Computed ; Adult ; Femur Neck/surgery*