[Structural design and evaluation of bone remodeling effect of fracture internal fixation implants with time-varying stiffness].

The stiffness of an ideal fracture internal fixation implant should have a time-varying performance, so that the fracture can generate reasonable mechanical stimulation at different healing stages, and biodegradable materials meet this performance. A topology optimization design method for composite structures of fracture internal fixation implants with time-varying stiffness is proposed, considering the time-dependent degradation process of materials. Using relative density and degradation residual rate to describe the distribution and degradation state of two materials with different degradation rates and elastic modulus, a coupled mathematical model of degradation simulation mechanical analysis was established. Biomaterial composite structures were designed based on variable density method to exhibit time-varying stiffness characteristics. Taking the bone plate used for the treatment of tibial fractures as an example, a composite structure bone plate with time-varying stiffness characteristics was designed using the proposed method. The optimization results showed that material 1 with high stiffness formed a columnar support structure, while material 2 with low stiffness was distributed at the degradation boundary and inside. Using a bone remodeling simulation model, the optimized bone plates were evaluated. After 11 months of remodeling, the average elastic modulus of callus using degradable time-varying stiffness plates, titanium alloy plates, and stainless steel plates were 8 634 MPa, 8 521 MPa, and 8 412 MPa, respectively, indicating that the use of degradable time-varying stiffness plates would result in better remodeling effects on the callus.

[A clinical study of HoloSight Orthopaedic Trauma Surgery Robot-assisted infra-acetabular screw placement for acetabular fractures].

Objective: To investigate the effectiveness of HoloSight Orthopaedic Trauma Surgery Robot-assisted infra-acetabular screw placement for treatment of acetabular fractures. Methods: The clinical data of 23 patients with acetabular fractures treated with open reduction and internal fixation and infra-acetabular screw placement in two medical centers between June 2022 and October 2023 were retrospectively analyzed. According to the the method of infra-acetabular screw placement, the patients were divided into navigation group (10 cases, using HoloSight Orthopaedic Trauma Surgery Robot-assisted screw placement) and freehand group (13 cases, using traditional X-ray fluoroscopy to guide screw placement). There was no significant difference in gender, age, body mass index, cause of injury, time from injury to operation, and Judet-Letournel classification between the two groups ( P>0.05). The time of infra-acetabular screw placement, the fluoroscopy frequency, the guide pin adjustment times, the quality of screw placement, the quality of fracture reduction, and the function of hip joint were compared between the two groups. Results: All patients completed the operation successfully. The time of screw placement, the fluoroscopy frequency, and guide pin adjustment times in the navigation group were significantly less than those in the freehand group ( P<0.05). The quality of screw placement in the navigation group was significantly better than that in the freehand group ( P<0.05). Patients in both groups were followed up 6-11 months, with an average of 7.7 months. There were 9 and 9 cases in the navigation group and the freehand group who achieved excellent and good fracture reduction quality at 1 week after operation, and 12 and 12 cases with excellent and good hip joint function at last follow-up, respectively, and there was no significant difference between the two groups ( P>0.05). The fractures in both groups healed well, and there was no significant difference in healing time ( P>0.05). During the follow-up, there was no complication related to screw placement, such as failure of internal fixation, vascular and nerve injury, incisional hernia. Conclusion: In the treatment of acetabular fractures, compared with the traditional freehand screw placement, the HoloSight Orthopaedic Trauma Surgery Robot-assisted screw placement can reduce the time of screw placement, improve the accuracy of screw placement, and reduce the amount of radiation, which is an efficient, accurate, and safe surgical method.

[Comparison of effectiveness of long and short proximal femoral nail anti-rotation in treatment of type A2.3 intertrochanteric fracture of femur].

Objective: To compare the effectiveness of long and short proximal femoral nail anti-rotation (PFNA) in the treatment of type A2.3 intertrochanteric fracture of femur (IFF). Methods: The clinical data of 54 patients with type A2.3 IFF admitted between January 2020 and December 2022 were retrospectively analyzed. According to the length of PFNA nail used in the operation, they were divided into long nail group (PFNA nail length>240 mm, 24 cases) and short nail group (PFNA nail length≤240 mm, 30 cases). There was no significant difference in baseline data such as gender, age, fracture side, body mass index, and time from fracture to operation between the two groups ( P>0.05). The operation time, intraoperative blood loss, intraoperative fluoroscopy frequency, intraoperative reduction quality score, fracture healing, and complications of the two groups were recorded and compared. Harris score was used to evaluate the hip function of patients at 1 year after operation. According to the relationship between the fracture line of type A2.3 IFF and the lesser trochanter, the two groups of patients were divided into type Ⅰ(the fracture line extends to the level of the lesser trochanter), type Ⅱ(the fracture line extends to less than 2 cm below the lesser trochanter), and type Ⅲ (the fracture line extends to more than 2 cm below the lesser trochanter), and the postoperative stability and internal fixator loosening of each subtype were evaluated. Results: The operation time, intraoperative blood loss, and intraoperative fluoroscopy frequency in short nail group were significantly less than those in long nail group ( P<0.05). There was no significant difference in the intraoperative reduction quality score between the two groups ( P>0.05). Patients in both groups were followed up 12-18 months, with an average of 13.5 months. The postoperative stability score of short nail group was significantly lower than that of long nail group ( P<0.05). The Harris score in the long nail group was significantly higher than that in the short nail group at 1 year after operation ( P<0.05), but there was no significant difference in Harris score grading between the two groups ( P>0.05). Complications occurred in 3 cases of the long nail group (including 1 case of coxa varus caused by external nail entry point and 2 cases of loose internal fixator), and 7 cases of the short nail group (including 1 case of coxa varus caused by external nail entry point and 6 cases of loose internal fixator). Neither group had any anterior femoral arch damage, there was no significant difference in the incidence of complications between the two groups ( P>0.05). The number of type Ⅲ patients was relatively small and not included in the statistics; there was no significant difference in the postoperative stability score and the incidence of internal fixator loosening between the long and short nail groups in type Ⅰ patients ( P>0.05). In type Ⅱ patients, the postoperative stability score and the incidence of internal fixation loosening in the long nail group were significantly better than those in the short nail group ( P<0.05). Conclusion: Long PFNA fixation for type A2.3 IFF has longer operation time and more intraoperative blood loss, but the overall stability of fracture is better after operation. For type A2.3 IFF with fracture line extending to less than 2 cm below the lesser trochanter, long PFNA is used for fixation, although the surgical trauma is large, but the postoperative stability is better than that of short PFNA; for type A2.3 IFF with fracture line extending to the lesser trochanter, there is no significant difference in postoperative stability between long and short PFNAs.

Comparison of tibial fracture plate length, placement, and fibular integrity effects on plate integrity through finite element analysis.

Minimally invasive plate osteosynthesis is the most commonly used minimally invasive surgery technique for tibial fractures, possibly involving single or dual plate methods. Herein, we performed a finite element analysis to investigate plate strength according to the plate type, length, and presence of a fibula by constructing a three-dimensional tibia model. A thickness of 20 mm was cut 50 mm distal from the lateral plateau, and the ligaments were created. Plates were modeled with lengths of 150, 200, and 250 mm and mounted to the tibia. Screws were arranged to avoid overlapping in the dual plating. The von-Mises stress applied to the plates was measured by applying a load of 1 body weight. Dual plates showed the least stress with low displacement, followed by medial and lateral plates. As the plate length increased, the average stress gradually decreased, increasing plate safety. The difference in the influence of the fibula depending on the presence of proximal fibula osteotomy showed that the average stress increased by 35% following proximal fibula osteotomy in the D1(Plate type: Dual plate, Medial plate length: 150 mm, Lateral plate length: 200 mm, Non Proximal fibula osteotomy) and D1P(Plate type: Dual plate, Medial plate length: 150 mm, Lateral plate length: 200 mm, Proximal fibula osteotomy) models, confirming the necessity of the fibula model. There is no consensus guideline for treatment of this kind of fracture case. A single fracture plate can decrease the risk of skin damage, ligament damage, and wound infection, but because of its design, it cannot provide sufficient stability and satisfactory reduction of the condylar fragment, especially in cases of comminution or coronal fracture. So, these results will help clinicians make an informed choice on which plate to use in patients with tibial fractures.

Biomechanical Comparison of Fixation Methods for Posterior Wall Fractures of the Acetabulum: Conventional Reconstruction Plate vs. Spring Plate vs. Variable Angle Locking Compression Plate.

Background and Objectives: Acetabular fractures, though infrequent, present considerable challenges in treatment due to their association with high-energy trauma and poor prognoses. Posterior wall fractures, the most common type among them, typically have a more favorable prognosis compared to other types. Anatomical reduction and stable fixation of the posterior wall are crucial for optimal treatment outcomes. This study aimed to biomechanically compare three commonly used fixation methods for posterior wall fractures of the acetabulum-a conventional reconstruction plate, a spring plate, and a 2.7 mm variable angle locking compression plate (VA-LCP). Materials and Methods: The study utilized 6 fresh-frozen cadavers, yielding 12 hemipelvises free from prior trauma or surgery. Three fixation methods were compared using a simple acetabulum posterior wall fracture model. Fixation was performed by an orthopedic specialist, with prebending of plates to minimize errors. Hemipelvises were subjected to quasi-static and cyclic loading tests, measuring fracture gap, stiffness, and displacement under load. Results: It showed no significant differences in fracture gap among the three fixation methods under cyclic loading conditions simulating walking. However, the conventional reconstruction plate exhibited a greater stiffness compared to the spring and variable angle plates. Fatigue analysis revealed no significant differences among the plates, indicating a similar stability throughout cyclic loading. Despite differences in stiffness, all three fixation methods demonstrated adequate stability under loading conditions. Conclusions: While the conventional reconstruction plate demonstrated a superior stiffness, all three fixation methods provided sufficient stability under cyclic loading conditions similar to walking. This suggests that postoperative limitations are unlikely with any of the three methods, provided excessive activities are avoided. Furthermore, the variable angle plate-like the spring plate-offers an appropriate stability for fragment-specific fixation, supporting its use in surgical applications. These findings contribute to understanding the biomechanical performance of different fixation methods for acetabular fractures, facilitating improved surgical outcomes in challenging cases.

Anterolateral Dual Plate Fixation for Distal Metaphyseal-Diaphyseal Junction Fractures of the Humerus: Biomechanical Finite Element Analysis with Clinical Results.

Background: Distal metaphyseal-diaphyseal junction fractures of the humerus are a subset of injuries between humeral shaft fractures and distal intra-articular humerus fractures. A lack of space for distal fixation and the unique anatomy of concave curvature create difficulties during operative treatment. The closely lying radial nerve is another major concern. The aim of this study was to determine whether anterolateral dual plate fixation could be effective for a distal junctional fracture of the humerus both biomechanically and clinically. Methods: A right humerus 3-dimensional (3D) model was obtained based on plain radiographs and computed tomography data of patients. Two fractures, a spiral type and a spiral wedge type, were constructed. Three-dimensional models of locking compression plates and screws were constructed using materials provided by the manufacturer. The experiment was conducted by using COMSOL Multiphysics, a finite element analysis, solver, and simulation software package. For the clinical study, from July 2008 to March 2021, a total of 72 patients were included. Their medical records were retrospectively reviewed to obtain patient demographics, elbow range of motion, Disabilities of the Arm, Shoulder and Hand (DASH) scores, Mayo Elbow Performance Scores (MEPS), and hand grip strength. Results: No fracture fixation construct completely restored stiffness comparable to the intact model in torsion or compression. Combinations of the 7-hole and 5-hole plates and the 8-hole and 6-hole plates showed superior structural stiffness and stress than those with single lateral plates. At least 3 screws (6 cortices) should be inserted into the lateral plate to reduce the load effectively. For the anterior plate, it was sufficient to purchase only the near cortex. Regarding clinical results of the surgery, the range of motion showed satisfactory results in elbow flexion, elbow extension, and forearm rotation. The average DASH score was 4.3 and the average MEPS was 88.2. Conclusions: Anterolateral dual plate fixation was biomechanically superior to the single-plate method in the finite element analysis of a distal junctional fracture of the humerus model. Anterolateral dual plate fixation was also clinically effective in a large cohort of patients with distal junctional fractures of the humerus.

A finite element analysis of a low-profile femoral neck system of screws in sleeves in a vertical femoral neck fracture model.

BACKGROUND: Femoral neck system (FNS) has exhibited some drawbacks, such as non-fit of the plate with the lateral femoral cortex, postoperative pain, and the potential risk of subtrochanteric fractures. We have developed a low-profile FNS system that addresses some compatibility issues in FNS. In this study, we conducted finite element analysis on the 1-hole FNS (1 H-FNS), 2-holes FNS (2 H-FNS), and low-profile FNS (LP-FNS) and compared their biomechanical performance. METHODS: After the mesh convergence analysis, we established three groups of 1 H-FNS, 2 H-FNS, and LP-FNS. The interfragmentary gap, sliding distance, shear stress, and compressive stress and the bone-implant interface compression stress, stiffness, and displacement were determined under the neutral, flexion, or extension conditions of the hip joint, respectively. The stress and displacement of the femur after the implant removal were also investigated. RESULTS: (1) There were no obvious differences among the three FNS groups in terms of the IFM distance. However, the LP-FNS group showed less rotational angle compared with conventional FNS (neutral: 1 H-FNS, -61.64%; 2 H-FNS, -45.40%). Also, the maximum bone-implant interface compression stress was obviously decreased under the neutral, flexion, or extension conditions of the hip joint (1 H-FNS: -6.47%, -20.59%, or -4.49%; 2 H-FNS: -3.11%, 16.70%, or -7.03%; respectively). (2) After the implant removal, there was no notable difference in the maximum displacement between the three groups, but the maximum von Mises stress displayed a notable difference between LP-FNS and 1 H-FNS groups (-15.27%) except for the difference between LP-FNS and 2 H-FNS groups (-4.57%). CONCLUSIONS: The LP-FNS may not only provide the same biomechanical stabilities as the 1 H-FNS and 2 H-FNS, but also have more advantages in rotational resistance especially under the neutral condition of the hip joint, in the bone-implant interface compression stress, and after the implant removal. In addition, the 1 H-FNS and 2 H-FNS have similar biomechanical stabilities except for the maximum von Mises stress after the implant removal. The femur after the LP-FNS removal not only is subjected to relatively little stress but also minimizes stress concentration areas.

Antegrade anterior column acetabulum fracture fixation with cannulated compression headless screws-A biomechanical study on standardized osteoporotic artificial bone.

PURPOSE: Due to the increase in life expectancy and high-energy traumas, anterior column acetabular fractures (ACFs) are also increasing. While open reduction and internal fixation (ORIF) is still the standard surgical procedure, minimally invasive, percutaneous fixation of osteoporotic acetabulum fractures (AF) are growing in popularity. The aim of this biomechanical study was to evaluate the biomechanical competence following antegrade fixation with a standard screw versus a cannulated compression headless screw. METHODS: Eight anatomical osteoporotic composite pelvises were given an anterior column fracture. Two groups of eight specimens each (n = 8) for fixation with either a 6.5 mm cannulated compression headless screw in group Anterior Acetabulum Canulated Compression Headless Screw (AACCH), or with a 6.5 mm partially threaded cannulated screw in group Anterior Acetabulum Standard Screw (AASS) where compared. Each specimen was biomechanically loaded cyclically at a rate of 2 Hz with monotonically increasing compressive load until failure. Motions were assessed by means of optical motion tracking. RESULTS: Initial construct stiffness trended higher in group AACCH at 152.4 ± 23.1 N/mm compared to group AASS at 118.5 ± 34.3 N/mm, p = 0.051. Numbers of cycles and corresponding peak load at failure, were significantly higher in group AACCH at 6734 ± 1669 cycles and 873.4 ± 166.9 N versus group AASS at 4440 ± 2063 cycles and 644.0 ± 206.3 N, p = 0.041. Failure modes were breakout of the screws around the proximal entry point. CONCLUSION: From a biomechanical perspective, group AACCH was associated with superior biomechanical competence compared to standard partially threaded cannulated screws and could therefore be considered as valid alternative for fixation of anterior acetabulum fractures.

A Novel Bone-Screw-Fastener Demonstrates Greater Maximum Compression Force Before Failure Compared With a Traditional Buttress Screw.

OBJECTIVES: This study compared the maximal compression force before thread stripping of the novel bone-screw-fastener (BSF) with the traditional buttress screw (TBS) in synthetic osteoporotic and cadaveric bone models. METHODS: The maximum compression force of the plate-bone interface before loss of screw purchase during screw tightening was measured between self-tapping 3.5-mm BSF and 3.5-mm TBS using calibrated load cells. Three synthetic biomechanical models were used: a synthetic osteoporotic diaphysis (model 1), a 3-layer biomechanical polyurethane foam with 50-10-50 pounds-per-cubic-foot layering (model 2), and a 3-layer polyurethane foam with 50-15-50 pounds-per-cubic-foot layering (model 3). For the cadaveric metaphyseal model, 3 sets of cadaveric tibial plafonds and 3 sets of cadaveric tibial plateaus were used. A plate with sensors between the bone and plate interface was used to measure compression force during screw tightening in the synthetic bone models, while an annular load cell that measured screw compression as it slid through a guide was used to measure compression in the cadaver models. RESULTS: Across all synthetic osteoporotic bone models, the BSF demonstrated greater maximal compression force before stripping compared with the TBS [model 1, 155.51 N (SD = 7.77 N) versus 138.78 N (SD = 12.74 N), P = 0.036; model 2, 218.14 N (SD = 14.15 N) versus 110.23 N (SD = 8.00 N), P < 0.001; model 3, 382.72 N (SD = 20.15) versus 341.09 N (SD = 15.57 N), P = 0.003]. The BSF had greater maximal compression force for the overall cadaver trials, the tibial plafond trials, and the tibial plateau trials [overall, 111.27 N vs. 97.54 N (SD 32.32 N), P = 0.002; plafond, 149.6 N versus 132.92 N (SD 31.32 N), P = 0.006; plateau, 81.33 N versus 69.89 N (SD 33.38 N), P = 0.03]. CONCLUSIONS: The novel bone-screw-fastener generated 11%-65% greater maximal compression force than the TBS in synthetic osteoporotic and cadaveric metaphyseal bone models. A greater compression force may increase construct stability, facilitate early weight-bearing, and reduce construct failure.

The Scapular Skiver Screw: A Useful Fixation Technique for Inferior Glenoid and Scapular Neck Fractures.

SUMMARY: The inferior glenoid and scapular neck are common locations for scapular fractures. Operative exposures for reduction and fixation can be challenging, and frequently, the proximal fracture planes are not conducive to optimal fixation with a plate alone. The purpose of this article was to describe a new technique for enhancing fixation in specific inferior glenoid fractures using a single cortical lag screw.

Fragment size of lateral Hoffa fractures determines screw fixation trajectory: a human cadaveric cohort study.

BACKGROUND AND PURPOSE: Recommendations regarding fragment-size-dependent screw fixation trajectory for coronal plane fractures of the posterior femoral condyles (Hoffa fractures) are lacking. The aim of this study was to compare the biomechanical properties of anteroposterior (AP) and crossed posteroanterior (PA) screw fixations across differently sized Hoffa fractures on human cadaveric femora. PATIENTS AND METHODS: 4 different sizes of lateral Hoffa fractures (n = 12 x 4) were created in 48 distal human femora according to the Letenneur classification: (i) type I, (ii) type IIa, (ii) type IIb, and (iv) type IIc. Based on bone mineral density (BMD), specimens were assigned to the 4 fracture clusters and each cluster was further assigned to fixation with either AP (n = 6) or crossed PA screws (n = 6) to ensure homogeneity of BMD values and comparability between the different test conditions. All specimens were biomechanically tested under progressively increasing cyclic loading until failure, capturing the interfragmentary movements via motion tracking. RESULTS: For Letenneur type I fractures, kilocycles to failure (mean difference [∆] 2.1, 95% confidence interval [CI] -1.3 to 5.5), failure load (∆ 105 N, CI -83 to 293), axial displacement (∆ 0.3 mm, CI -0.8 to 1.3), and fragment rotation (∆ 0.5°, CI -3.2 to 2.1) over 5.0 kilocycles did not differ significantly between the 2 screw trajectories. For each separate subtype of Letenneur type II fractures, fixation with crossed PA screws resulted in significantly higher kilocycles to failure (∆ 6.7, CI 3.3-10.1 to ∆ 8.9, CI 5.5-12.3) and failure load (∆ 275 N, CI 87-463 to ∆ 438, CI 250-626), as well as, less axial displacement from 3.0 kilocycles onwards (∆ 0.4°, CI 0.03-0.7 to ∆ 0.5°, CI 0.01-0.9) compared with AP screw fixation. CONCLUSION: Irrespective of the size of Letenneur type II fractures, crossed PA screw fixation provided greater biomechanical stability than AP-configured screws, whereas both screw fixation techniques demonstrated comparable biomechanical competence for Letenneur type I fractures. Fragment-size-dependent treatment strategies might be helpful to determine not only the screw configuration but also the surgical approach.

Surgical outcomes of robotic-assisted percutaneous fixation for thoracolumbar fractures in patients with ankylosing spondylitis.

BACKGROUND: Spinal fractures in patients with ankylosing spondylitis (AS) mainly present as instability, involving all three columns of the spine, and surgical intervention is often considered necessary. However, in AS patients, the significant alterations in bony structure and anatomy result in a lack of identifiable landmarks, which increases the difficulty of pedicle screw implantation. Therefore, we present the clinical outcomes of robotic-assisted percutaneous fixation for thoracolumbar fractures in patients with AS. METHODS: A retrospective review was conducted on a series of 12 patients diagnosed with AS. All patients sustained thoracolumbar fractures between October 2018 and October 2022 and underwent posterior robotic-assisted percutaneous fixation procedures. Outcomes of interest included operative time, intra-operative blood loss, complications, duration of hospital stay and fracture union. The clinical outcomes were assessed using the visual analogue scale (VAS) and Oswestry Disability Index (ODI). To investigate the achieved operative correction, pre- and postoperative radiographs in the lateral plane were analyzed by measuring the Cobb angle. RESULTS: The 12 patients had a mean age of 62.8 ± 13.0 years and a mean follow-up duration of 32.7 ± 18.9 months. Mean hospital stay duration was 15 ± 8.0 days. The mean operative time was 119.6 ± 32.2 min, and the median blood loss was 50 (50, 250) ml. The VAS value improved from 6.8 ± 0.9 preoperatively to 1.3 ± 1.0 at the final follow-up (P < 0.05). The ODI value improved from 83.6 ± 6.1% preoperatively to 11.8 ± 6.6% at the latest follow-up (P < 0.05). The average Cobb angle changed from 15.2 ± 11.0 pre-operatively to 8.3 ± 7.1 at final follow-up (P < 0.05). Bone healing was consistently achieved, with an average healing time of 6 (5.3, 7.0) months. Of the 108 screws implanted, 2 (1.9%) were improperly positioned. One patient experienced delayed nerve injury after the operation, but the nerve function returned to normal upon discharge. CONCLUSION: Posterior robotic-assisted percutaneous internal fixation can be used as an ideal surgical treatment for thoracolumbar fractures in AS patients. However, while robot-assisted pedicle screw placement can enhance the accuracy of pedicle screw insertion, it should not be relied upon solely.

[Comparison of open reduction hollow nail anchoring system with loop plate fixation under arthroscopy for the treatment of posterior cruciate ligament avulsion fractures].

OBJECTIVE: To compare clinical effect between open reduction and fixation with cannulated screw and threaded rivet via posteromedial approach versus arthroscopic Endobutton plate fixation in treating posterior cruciate ligament avulsion fractures. METHODS: Clinical data of 38 patients with posterior cruciate ligament avulsion fractures from July 2020 to December 2021 were analyzed retrospectively, and divided into open reduction and internal fixation group (posterior medial approach hollow anchor system fixation) and arthroscopic fixation group (Endobutton with loop plate fixation under arthroscopy). There were 20 patients in open reduction and internal fixation group, including 16 males and 4 females, aged from 26 to 74 years old with an average of (42.9±18.8) years old;13 patients on the left side and 7 patients on the right side;12 patients were classified to typeⅡand 8 patiens with type Ⅲ according to Meyers-McKeever fractures classification;14 patients were gradeⅡand 6 patients were grade Ⅲ in back drawer test. There were 18 patients in arthroscopic fixation group, including 11 males and 7 females;aged from 24 to 70 years old with an average of (53.5±13.4) years old;11 patients on the left side and 7 patients on the right side;10 patients were classified to typeⅡand 8 patiens with type Ⅲ according to Meyers-McKeever fractures classification;11 patients were gradeⅡand 7 patients were grade Ⅲ in back drawer test. Operation time, blood loss, and quality of immediate reduction were compared between two groups. Knee range of motion, knee back drawer test, and International Knee Documentation Committee(IKDC) grading, KT2000 stability evaluation and Lysholm function score of knee joint were compared at 6 months after operation. RESULTS: All patients were followed up for 8 to 16 months with an average of (12.3±1.9) months. There were no complications such as incision infection, fracture malunion or non-union, and internal fixation loosening occurred. The avulsion fractures of knee joint were reached to imaging healing standard at 6 months after operation. Operation time and blood loss in open reduction and internal fixation group were (56.4±7.1) min and (63.2±10.2) ml, while (89.9±7.4) min and (27.7±8.7) ml in arthroscopic fixation group, respectively, and had significant difference between two groups (P<0.05). There were no differences in immediate reduction quality (χ2=0.257, P=0.612), knee joint range of motion at 6 months after opertaion (t=0.492, P=0.626), knee joint rear drawer test ( χ2=0.320, P=0.572), IKDC classification of knee joint (χ2=0.127, P=0.938), KT2000 stability evaluation (χ2=0.070, P=0.791), and knee Lysholm function score (t=0.092, P=0.282) between two groups. CONCLUSION: Posterior medial approach with hollow anchoring system fixation and arthroscopic Endobutton with loop plate fixation for the treatment of posterior cruciate ligament tibial occlusion avulsion fracture could achieve satisfactory clinical results, and arthroscopic surgery has less bleeding, but also has a longer learning curve and longer operation time than traditional incision surgery. The surgeon needs to make a choice according to clinical situation of patient and their own surgical inclination.

Torsional stability of fixation methods in basicervical femoral neck fractures: a biomechanical study.

BACKGROUND: Basicervical femoral neck fracture is a rare proximal femur fracture with a high implant failure rate. Biomechanical comparisons between cephalomedullary nails (CMNs) and dynamic hip screws (DHSs) under torsion loading are lacking. This study compared the biomechanical performance of three fixations for basicervical femoral neck fractures under torsion load during early ambulation. METHODS: The biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability. RESULTS: The EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1-5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs. CONCLUSIONS: Titanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout.

Intraoperative assessment of the dorso-ulnar fragment stability with stress fluoroscopy: An observational study.

This study aims to investigate the effectiveness of intraoperative stress radiographs in evaluating the stability and fixation adequacy of the dorso-ulnar fragment (DUF) after volar plate application. Sixty-four patients who underwent open reduction and internal fixation due to comminuted distal radius fracture accompanied by DUF between May 2020 and February 2022 were reviewed retrospectively. Two groups were compared, with and without stress radiographs used in addition to routine fluoroscopic imaging during the surgical treatment of distal radius fractures. DUF sizes and fracture classifications were made according to preoperative computed tomography. Displacement of the DUF, dorsal cortex screw penetration, and the number of screws inserted into the DUF were evaluated on immediate postoperative CT scans and direct radiographs. DUF displacement at the patients' last follow-up was significantly higher in the control group (1.62 mm) than in the additional stress fluoroscopy applied group (0.53 mm). It was observed that the amount of displacement increased as the dorso-volar size of the DUF decreased. No significant difference was observed in dorsal cortex screw penetrations between the 2 groups. In the additional stress fluoroscopy applied group, stabilization rates with at least 1 screw over volar-locking plate for DUF were significantly higher (P < .001). Compared to the stress fluoroscopy group, the change in ulnar variance (P < .001) and volar tilt (P < .001) was significantly higher in the control group in the last follow-up radiography. No significant difference was observed between the implant removal rates of both groups. Evaluation of the stability of the DUF with stress radiographs after fixation is an effective method to reveal the need for additional fixation. Dorsal stress radiographs allow dynamic evaluation of fixation strength.

Better outcomes using suture button compared to screw fixation in talofibular syndesmotic injuries of the ankle: a level I evidence-based meta-analysis.

INTRODUCTION: The present meta-analysis evaluated current level I clinical trials which compared the use of a suture button (SB) versus syndesmotic screw (SS) fixation techniques for syndesmosis injuries of the ankle. The outcomes of interest were to compare patient-reported outcome measures (PROMs) and complications. It was hypothesised that SB might achieve better PROMs along with a lower rate of complications. METHODS: This study was conducted according to the 2020 PRISMA statement. In August 2023, PubMed, Web of Science, Google Scholar, and Embase were accessed. All the randomised controlled trials (RCTs) which compared SB versus SS fixation for syndesmosis injuries of the ankle were accessed. Data concerning the American Orthopaedic Foot & Ankle Society (AOFAS), and Olerud-Molander score (OMS) were collected at baseline and at last follow-up. Data on implant failure, implant removal, and joint malreduction were also retrieved. RESULTS: Data from seven RCTs (490 patients) were collected. 33% (161 of 490) were women. The mean length of the follow-up was 30.8 ± 27.4 months. The mean age of the patients was 41.1 ± 4.1 years. Between the two groups (SB and SS), comparability was found in the mean age, and men:women ratio. The SS group evidenced lower OMS (P = 0.0006) and lower AOFAS (P = 0.03). The SS group evidenced a greater rate of implant failure (P = 0.0003), implant removal (P = 0.0005), and malreduction (P = 0.04). CONCLUSION: Suture button fixation might perform better than the syndesmotic screw fixation in syndesmotic injuries of the ankle.

Motion preservation for open book injuries of the pubic symphysis -a biomechanical cadaver study.

INTRODUCTION: Open book injuries are challenging injuries that oftentimes require surgical treatment. Currently, treatment is performed with symphyseal plating requiring extensive surgery and entirely limiting physiological movement of the symphyseal joint, frequently resulting in implant failure. Therefore, we investigated the biomechanical properties of a minimally invasive tape suture construct (modified SpeedBridge™) as an alternative stabilization technique for the treatment of open book injuries in human cadaver pelvic rings. MATERIALS AND METHODS: The symphysis of 9 human cadaver pelvises was dissected and dilated to 3 cm creating an open book injury. Next, the two osteosynthesis methods (plating, modified SpeedBridge™) were applied. All specimens then underwent cyclic horizontal and vertical loading, simulating biomechanical forces while sitting, standing and walking. For statistical analysis, 3D dislocation (mm) was calculated. RESULTS: Total displacement (mm) of the pubic symphysis displayed the following means and standard deviations: native group 1.34 ± 0.62 mm, open book group 3.01 ± 1.26 mm, tape group 1.94 ± 0.59 mm and plate group 1.37 ± 0.41 mm. Comparison between native and open book (p = 0.029), open book and plate (p = 0.004), open book and tape (p = 0.031), as well as tape and plate group (p = 0.002) showed significant differences. No significant differences were found when comparing the native and tape (p = 0.059), as well as the native and plate (p = 0.999) group. CONCLUSION: While both osteosynthesis techniques sufficiently stabilized the injury, symphyseal plating displayed the highest rigidity. The modified SpeedBridge™ as a tape suture construct provided statistically sufficient biomechanical stability while maintaining symphyseal micro mobility, consequently allowing ligamental healing of the injured joint without iatrogenic arthrodesis.

Biomechanical analysis of push-pull principle versus traditional approach in locking plates for proximal humeral fracture treatment.

INTRODUCTION: Proximal humerus fractures are usually treated with locking plates, which could present recurrence, screw penetration, joint varization. The push-pull principle was introduced to prevent these risks and showed promising results; a dedicated design was then developed and this feasibility study aims to compare the biomechanical performances of such dedicated push-pull plate with the traditional locking plate using finite elements. MATERIALS AND METHODS: The humerus geometry was obtained from Sawbone CT-scans; the geometries of a traditional locking plate and of the dedicated push-pull one were used. A fracture was added below the humeral head and the plates were virtually implanted. The wire pulling mechanism was simulated connecting the plate to the humeral head apex, considering two levels of tension. Three testing set-ups (axial, torsion and compression bending) were simulated. Stress distributions on bone, plate and screws were measured. RESULTS: Stress distribution on the distal humerus was similar for both plates. Stress distribution on the proximal humerus was more homogeneous for the push-pull model, showing less unloaded sections (up to 78%). The different levels of tension applied to the wire returned slight differences in terms of stress values, but the comparison with the traditional approach gave similar outcomes. CONCLUSIONS: More homogeneous stress distribution is found with the push-pull plate in all three testing set-ups, showing lower unloaded areas (and thus lower stress-shielding) compared to the traditional plate; the screws implemented returned to be all loaded in at least one of the set-ups, thus showing that they all contribute to plate stability.