BACKGROUND

In the Philippines and other developing countries, access to high-stability external fixators for traumainduced bone fracture management is limited, as modular external fixators, especially those with snap-on features, are manufactured overseas and are prohibitively expensive for most Filipino patients.

This study aimed to assess the biomechanical performance of a locally-developed modular external fixator prototype for tibial diaphyseal fractures in comparison to available external fixators, such as Roger Anderson and Hoffmann. This provides an initial evaluation for the use of the external fixator as an alternative in terms of its stability.

Using axial compression testing compliant with the ASTM F1541-24 standards, the ultimate strength, yield strength, safe strength, and stiffness were measured across various fixator types and tightening mechanisms, with or without the aid of a wrench. Statistical tools such as the t-test assuming equal variances, one-way analysis of variance, and Tukey-Kramer test with a 0.05 level of significance were used to determine any significant differences.

The mechanical performance of the external fixator prototype increased by a factor of 1.5 to 2.5 after the clamps were tightened with the wrench. However, when hand-tightened, it still performed sufficiently, showing a comparable mechanical performance with the Roger Anderson Fixator. In terms of the ultimate, safe, and yield strengths, it performed competitively in comparison with the Hoffmann system. However, there is a significant difference in stiffness between the prototype and the Hoffmann system.

The locally-developed external fixator was comparable biomechanically to the commercially available external fixators and the prototypes in different studies.

OBJECTIVES: Oblique lateral interbody fusion (OLIF) has become a well-established treatment for lumbar spinal stenosis (LSS) due to its advantages of being minimally invasive, effective, and associated with fewer complications. However, relying solely on lateral fixation provides limited strength and uneven load distribution. Conventional posterior bilateral fixation after OLIF typically requires intraoperative repositioning, increases fluoroscopy frequency, and involves extensive dissection of posterior muscles and soft tissues, resulting in greater trauma, blood loss, and risks of dural tear, nerve root injury, and persistent postoperative low back pain. This study aims to compare the clinical efficacy of robot-assisted single-position OLIF with lateral plating and posterior unilateral fixation, OLIF with lateral fixation alone, and OLIF combined with posterior bilateral fixation for treating single-segment LSS, and to explore how to enhance fixation stability, reduce trauma, and achieve precise minimally invasive outcomes without changing patient positioning. METHODS: A retrospective analysis was conducted on the clinical data from patients treated for single-segment LSS between January 2020 and June 2023 at the First Affiliated Hospital of Kunming Medical University. Patients were divided into 3 groups: Robot group (robot-assisted single-position OLIF with lateral plate and posterior unilateral fixation, 33 cases), lateral group (OLIF with lateral fixation alone, 52 cases), and combined group (OLIF with posterior bilateral fixation, 45 cases). Surgical time, intraoperative blood loss, fluoroscopy frequency, hospital stay, pedicle screw placement accuracy, and complication rates were recorded. Pain visual analogue scale (VAS) scores and Oswestry disability index (ODI) scores were assessed preoperatively, postoperatively, and at the final follow-up. Radiological evaluations (X-ray, computed tomography, and magnetic resonance imaging) measured interbody disc height (IDH), intervertebral foraminal height (IFH), and cross-sectional area (CSA) of the dural sac. Differences between pre- and postoperative imaging indices were statistically analyzed, and complication rates, fusion rates, and cage subsidence rates were recorded. RESULTS: All patients exhibited good positioning of internal fixation devices and cages, with significant symptom relief and no cases of spinal cord injury or symptom worsening. The follow-up time was (15.2±3.6) months. The operation time of the robot group was (70.62±8.99) min, which was longer than that of the lateral group (45.90±6.09) min and shorter than that of the combined group (110.12±8.44) min. The intraoperative blood loss of the robot group was (44.27±6.87) mL, which was more than that of the lateral group (33.58±9.73) mL and less than that of the combined group (79.19±10.35) mL. The number of intraoperative fluoroscopy times of the robot group was (9.49±2.25), which was comparable to that of the lateral group (7.45±2.02) but less than that of the combined group (12.24±4.25). The hospital stay of the robot group was (9.28±2.10) days, which was longer than that of the lateral group (7.95±1.91) days and shorter than that of the combined group (12.49±5.07) days. The screw placement accuracy of the robot group was 98.48%, which was higher than that of the combined group (90.55%). Postoperative and final follow-up VAS and ODI scores were significantly lower than preoperative scores in all 3 groups (all P<0.05), and there were no significant differences in preoperative VAS and ODI scores among the groups (all P>0.05). Radiologically, IDH, IFH, and CSA at the surgical segment were significantly increased postoperatively and at final follow-up compared to preoperatively and at final follow-up compared to preoperative values (all P<0.05), with no significant differences among the groups postoperatively (all P>0.05). Internal fixation remained stable during the follow-up period, and all cages achieved fusion at final follow-up. The intervertebral fusion rate of the robot-assisted group was 93.40%, which was similar to that of the combined group (95.56%) and higher than that of the lateral approach group (90.34%). The complication rate of the robot-assisted group was 6.1%, which was comparable to that of the combined group (8.9%) and lower than that of the lateral approach group (15.4%) (P<0.05). No cases of fixation loosening or breakage were observed throughout the follow-up period. CONCLUSIONS Robot-assisted single-position OLIF with lateral plate combined with posterior unilateral fixation effectively achieves indirect decompression and excellent spinal stability without the need for intraoperative repositioning. It provides high pedicle screw accuracy, reduces intraoperative blood loss, fluoroscopy times, and complication rates, offering a fully minimally invasive new treatment option for single-segment LSS.
Humans ; Spinal Stenosis/surgery* ; Robotic Surgical Procedures/methods* ; Lumbar Vertebrae/surgery* ; Spinal Fusion/instrumentation* ; Male ; Female ; Retrospective Studies ; Middle Aged ; Aged ; Treatment Outcome ; Bone Plates ; Minimally Invasive Surgical Procedures/methods* ; Adult

OBJECTIVES: To assess the biomechanical performance of a novel bridging plate for treating Rockwood III acromioclavicular joint dislocation. METHODS: A novel bridging plate structure was designed based on CT data from a patient with Rockwood type III acromioclavicular joint dislocation, and a finite element model of the bridging plate-acromioclavicular joint interaction was constructed. The stress and deformation characteristics and biomechanical compatibility of the plate under post-reduction, normal loading, and impact loading conditions were analyzed to evaluate its fixation mechanism and clinical advantages. RESULTS: The stiffness of the bridging system was 27.78 N/mm, close to that of acromioclavicular joint ligaments (26.05 N/mm) and meeting the requirements for flexible deformation. Under normal loading, the maximum stress in the bridging system was 88.29 MPa to sustain physiological activities; under impact loading, the maximum stress reached 480 MPa, and the cable underwent plastic deformation to dissipate energy and effectively buffer local stress concentrations, thereby reducing the risk of rigid bone fractures. The high-stress regions in the bone primarily occurred at the edges of the C1-C4 screw holes. The maximum bone stress was 0.762 MPa under normal loading and 5.963 MPa under impact loading, accounting for 2.86% and 1.66% of the corresponding bolt stresses, respectively. CONCLUSIONS The novel bridging plate is better adapted to biomechanical characteristics of the acromioclavicular joint compared to traditional internal fixation. This fixation system provides sufficient stability while allowing physiological micromotion to facilitate postoperative rehabilitation. Significant flexible deformation can occur at the connection between the fixation ring and the cable, and brittle materials should not be used in this region. The issue of stress concentration at the C1-C4 screw holes requires special attention in its clinical application.
Acromioclavicular Joint/surgery* ; Humans ; Bone Plates ; Biomechanical Phenomena ; Finite Element Analysis ; Joint Dislocations/surgery* ; Fracture Fixation, Internal/methods*

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

OBJECTIVES: Magnetic resonance imaging (MRI) was used to study the efficacy of modified anterior splint (MAS) combined with anterior repositioning splint (ARS) in maintaining the normal disk-condyle relationship. METHODS: We obtained clinical and imaging data of 10 patients with acute anterior disk displacement without reduction (ADDwoR) of the temporomandibular joint undergoing successful mandibular manipulation in the Affiliated Stomatological Hospital, Nanchang University from January to June 2024. The MAS and ARS were used for subsequent treatment. Maximum active mouth opening (MMO) and visual analogue score (VAS) were recorded before treatment and 2 weeks, 1 month, and 3 months after treatment. The changes in the disk-condyle relationship, disk-condyle angle, joint effusion, and double contour sign before and after treatment were analyzed through MRI. RESULTS: Three months after treatment, the MMO increased from 28.90 mm to 46.85 mm, VAS decreased from 4.68 to 0.61, and the disk-condyle angle decreased from 58.84° to 25.99°. MRI analysis found that 6 patients showed normal disk-condyle relationship, 2 patients exhibited displacement with reduction, and 2 patients exhibited ADDwoR. The disk-condyle angle was 58.84° before treatment and 25.99° after treatment. CONCLUSIONS The MAS combined with ARS could further stabilize the coordinated disk-condyle relationship and reduce the recurrence rate.
Humans ; Male ; Magnetic Resonance Imaging ; Female ; Adult ; Temporomandibular Joint Disorders/diagnostic imaging* ; Splints ; Middle Aged ; Mandible ; Temporomandibular Joint Disc ; Occlusal Splints ; Temporomandibular Joint ; Young Adult ; Joint Dislocations/therapy*

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 compare the short-term effectiveness between Gamma 3 intramedullary nails and Gamma 3 U-Blade system in the treatment of osteoporotic intertrochanteric fractures in the elderly. METHODS: A retrospective analysis was conducted on the clinical data of 124 elderly patients with osteoporotic intertrochanteric fractures, who were admitted between February 2020 and February 2023 and met the selection criteria. The fractures were fixed with Gamma 3 intramedullary nails in 65 patients (control group) and Gamma 3 U-Blade systems in 59 patients (UB group). The differences between the two groups were not significant in age, gender, body mass index, American Society of Anesthesiologists (ASA) classification, bone mineral density, time from injury to operation, fracture classification, and affected side ( P>0.05). The operation time, intraoperative blood loss, hospital stay, and fracture healing time were recorded; the tip-apex distance, fracture reduction quality, and lag screw position were evaluated on X-ray films at immediate after operation; the lag screw sliding distance and change value of neck-shaft angle were measured on X-ray films at last follow-up. Harris hip score at 1 year after operation and the occurrence of internal fixation-related complications were compared between the two groups. RESULTS: The operation time, intraoperative blood loss, and hospital stay in the UB group increased compared to the control group, but the differences were not significant ( P>0.05). All patients in both groups were followed up 12-24 months (mean, 17.1 months). At 12 months after operation, there was no significant difference in the Harris hip score between the two groups ( P<0.05). Radiological examination showed that there was no significant difference between the two groups ( P>0.05) in terms of tip-apex distance, fracture reduction quality, and lag screw position. Fractures healed in both groups, and there was no significant difference in healing time ( P>0.05). At last follow-up, the change value of neck-shaft angle and lag screw sliding distance in the UB group were significantly lower than those in the control group ( P<0.05). During follow-up, no related complications occurred in the UB group, while 6 cases (9.2%) in the control group experienced complications, and the difference in the incidence was significant ( P<0.05). CONCLUSION For the osteoporotic intertrochanteric fractures in the elderly, the Gamma 3 U-Blade system fixation can achieve good short-term effectiveness, with better imaging results compared to Gamma 3 intramedullary nails fixation.
Humans ; Retrospective Studies ; Hip Fractures/surgery* ; Male ; Female ; Aged ; Fracture Fixation, Intramedullary/methods* ; Osteoporotic Fractures/surgery* ; Bone Nails ; Bone Screws ; Aged, 80 and over ; Treatment Outcome ; Fracture Healing ; Operative Time ; Length of Stay

OBJECTIVE: To investigate the feasibility and effectiveness of the novel bone hook combined with finger-guided technique in the treatment of irreducible intertrochanteric femoral fractures in elderly. METHODS: Between January 2021 and August 2023, 23 elderly patients with irreducible intertrochanteric femoral fractures were treated with the novel bone hook combined with finger-guided technique. There were 10 males and 13 females; the age ranged from 68 to 93 years (mean, 76.2 years). The time from injury to operation ranged from 36 to 76 hours (mean, 51.2 hours). According to the classification standard proposed by TONG Dake et alin 2021, there were 10 cases of typeⅠA, 1 case of typeⅠB, 6 cases of type ⅡA, 4 cases of type ⅡB, and 2 cases of type ⅡC. The operation time, intraoperative blood loss, intraoperative fluoroscopy frequences, and quality of fracture reduction were recorded. The fracture healing time and occurrence of postoperative complications were observed during follow-up. At last follow-up, the Harris scoring system was used to evaluate the hip joint function. RESULTS: The operation time was 42-95 minutes (mean, 52.1 minutes). The intraoperative blood loss was 40-420 mL (mean, 126.5 mL). Intraoperative fluoroscopy was performed 14-34 times (mean, 20.7 times). According to the criteria proposed by Chang et al, the quality of fracture reduction was rated as good in 20 cases and acceptable in 3 cases. All patients were followed up 6-20 months (mean, 10.2 months). X-ray film showed that all fractures healed with the healing time of 3.0-5.5 months (mean, 4.0 months). At last follow-up, the Harris score of the hip joint ranged from 82 to 97 points (mean, 90.4 points). Among them, 14 cases were rated as excellent and 9 cases as good. No complication such as coxa vara, cutting of the cephalomedullary nail, nail withdrawal, or nail breakage occurred during follow-up. CONCLUSION The treatment of elderly patients with irreducible intertrochanteric femoral fractures by using the novel bone hook combined with finger-guided technique can achieve high-quality fracture reduction and fixation, and has a good effectiveness.
Humans ; Male ; Female ; Aged ; Aged, 80 and over ; Hip Fractures/diagnostic imaging* ; Fracture Fixation, Internal/instrumentation* ; Fracture Healing ; Treatment Outcome ; Operative Time ; Fracture Fixation, Intramedullary/instrumentation* ; Bone Nails ; Postoperative Complications/epidemiology* ; Feasibility Studies ; Fingers

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 explore the advantages and effectiveness of the independently developed intelligent orthopedic robot-assisted distal locking of femoral intramedullary nails. METHODS: Thirty-two adult cadaveric femur specimens were randomly divided into two groups, with 16 specimens in each group. The experimental group used the intelligent orthopedic robot to assist in the distal locking of femoral intramedullary nail holes, while the control group used the traditional method of manual locking under X-ray fluoroscopy. The locking time, fluoroscopy times, and the success rate of first locking were recorded and compared between the two groups. RESULTS: The locking time of the experimental group was (273.94±38.67) seconds, which was shorter than that of the control group [(378.38±152.72) seconds], and number of fluoroscopies was (4.56±0.81) times, which was less than that of the control group [(8.00±3.98) times]. The differences were significant [ MD=73.054 (-37.187, 85.813), P=0.049; MD=1.969 (-1.437, 2.563), P=0.002]. The first locking success rate of the experimental group was 100% (16/16), which was significantly higher than that of the control group (68.75%, 11/16) ( P=0.043). CONCLUSION The efficiency of distal locking of femoral intramedullary nails assisted by the intelligent orthopedic robot is significantly higher than that of the traditional manual locking method under fluoroscopy, as it can markedly reduce the time required for distal locking of femoral intramedullary nails, decrease intraoperative radiation exposure, and increase the success rate of locking.
Humans ; Fracture Fixation, Intramedullary/instrumentation* ; Bone Nails ; Fluoroscopy ; Femur/diagnostic imaging* ; Femoral Fractures/surgery* ; Robotic Surgical Procedures/instrumentation* ; Cadaver ; Adult ; Robotics ; Male