Preliminary Exploration: When Angiosome Meets Prefabricated Flaps.

Background The best known limitation to the use of prefabricated flaps is their limited survival area. One explanation for this is insufficient neovascularization. However, blood flow of prefabricated flaps is through their innate vascular network. This could lead one to conclude that angiosomes may impede blood perfusion. This study aims to settle this contradiction between theory and clinical practice. Methods We performed a two-stage operation of a prefabricated abdominal flap in a rat model. The rats were divided into five groups (n = 6/group). Group A: fixed pedicle at a horizontal angle; Group B: fixed pedicle at an oblique angle; Group C: fixed pedicle at a vertical angle; Group D: fixed pedicle in the same position as Group A; and Group E: axial flap. Groups A and B were prefabricated for 2 weeks and Groups C and D were prefabricated for 3 weeks. Macroscopic appearance was noted, and analysis of near-infrared fluorescence imaging and capillary density was performed. Results There was no significant difference in the flaps' survival area between Groups A and B. Group D had a significantly larger survival area when compared with Group C. The boundary between two angiosomes (medioventral line) seemed to limit the indocyanine green perfusion in Groups B, C, and E, while in Groups A and D, no such limitation was seen. Capillary density was positively correlated with neovascularization time. Conclusions Angiosomes impede blood perfusion in prefabricated flaps. Cross-bound neovascular vessels nourish the flap, thus overcoming the limitation of choke vessels.

[Biomechanical characteristics of retinaculum in the treatment of femoral neck fractures].

OBJECTIVE: To investigate the biomechanical characteristics of retinaculum in the treatment of femoral neck fractures. METHODS: The CT data of a 75-year-old female volunteer was processed by software to construct an intact femur model and femoral neck fracture model fixed with three cannulated screws, which were divided into models with retinaculum or not. The Von-Mises stress distribution and displacement were compared to analyze the stability differences between the different models to study the mechanical characteristics of the retinaculum in the treatment of femoral neck fractures. RESULTS: In the intact femur, the most obvious displacement appeared in the weight-bearing area of the femoral head, with retinaculum 0.381 37 mm, and without retinaculum 0.381 68 mm. The most concentrated part of the Von-Mises stress distribution was located in the medial and inferior part of the femoral neck, with retinaculum 11.80 MPa, without retinaculum 11.91 MPa. In the femoral neck fracture fixed with three cannulated screws model, the most obvious position of displacement also appeared in the weight-bearing area of the femoral head, with retinaculum 0.457 27 mm, without retinaculum 0.458 63 mm. The most concentrated part of the Von-Mises located at the medical and inferior part of the femoral neck, with retinaculum 59.22 MPa, without retinaculum 59.14 MPa. For the cannulated screws, the Von-Mises force peaks all appeared in the posterior and superior screw, with retinaculum 107.48 MPa, without retinaculum 110.84 MPa. Among the three screws, the Von-Mises stress of the anterior-superior screw was the smallest, which was 67.88 MPa vs 68.76 MPa in the retinaculum and non-retinaculum groups, respectively. CONCLUSION: The complete retinaculum has little effect on the stability of intact femur and femoral neck fractures with anatomical reduction after internal fixation, and cannot effectively improve the stability of the fracture end after the fracture.

[Surgical treatment for ipsilateral femoral neck and shaft fracture].

OBJECTIVE: To retrospectively analyze efficacy of single structure internal fixation and double structure internal fixation in the treatment of ipsilateral femoral shaft and neck fracture, and analyze their indications. METHODS: From June 2015 to December 2020, 21 patients with ipsilateral femoral shaft and femoral neck fracture were treated, including 14 males and 7 females, aged 23 to 69 years old with an average of(38.1±12.9) years old. According to different femoral shaft fracture sites, some patients were fixed with cephalomedullary implant for both femoral neck and the femoral shaft(single structure, InterTan or PFNA Ⅱ), some patients were fixed with cannulated screws for the femoral neck and a retrograde locking nail for the femoral shaft (dual structure), and postoperative function and complications were recorded during follow-up. In 10 cases of single-structure fixation, the femoral necks were all basicervical fractures, and the femoral shaft fractures were located in the proximal isthmus;11 cases were double-structure fixation, 9 cases in 11 were basal type of femoral neck, 2 cases in 11 were neck type, and the femoral shaft fractures were located in the isthmus and the distal isthmus. RESULTS: All patients were followed up for 12 to 27 months. No femoral head necrosis, deformity, delay or nonunion occurred in the patients with single-structure fixation, and no delayed union or nonunion occurred in femoral shaft fractures;At the final follow-up, Harris score of patients with single-structure fixation was 91.8±4.1, with 8 cases were excellent and 2 cases were good. The fractures of patients with dual-structure fixation achieved good union without femoral head necrosis, except 1 case of femoral shaft fracture had delayed union;At the final follow-up, Harris score of patients with dual-structure fixation was 92.4±5.9, 7 cases were excellent, 3 cases were good, and 1 case was fair. CONCLUSION: Good reduction and fixation is the key to the treatment of such fractures. Both the single-structure fixation and the dual-structure fixation are good methods, and it should be selected according to the locations of femoral shaft and femoral neck fractures. Single-structure fixation is a good choice for femoral shaft fractures located at the proximal isthmus and basal femoral neck fractures. For isthmus and distal femoral shaft fractures combined with ipsilateral femoral neck fractures, dual-structure fixation is recommended.

Finite element analysis of necessity of reduction and selection of internal fixation for valgus-impacted femoral neck fracture.

This study compared the biomechanical characteristics of different treatment strategies based on finite element analysis. Posterior tilt and valgus angle were measured on X-ray from ten valgus-impacted femoral neck fractures, and 7 finite element models that were generated to compare the stress and displacement. The results showed that in the intact femur, von Mises stress was concentrated at the medial and inferior sides of the femoral neck. In valgus-impacted femoral neck fractures, von Mises stress was at the same locations but was 5.66 times higher than that in the intact femur. When 3 cannulated screws were used for internal fixation, anatomic reduction diminished the stress at the fracture end from 140.6 to 59.14 MPa, although displacement increased from 0.228 to 0.450 mm. When the fracture was fixed with a sliding hip screw (SHS) + cannulated screw, there was less stress at the fracture end and greater displacement with anatomic reduction than that without reduction (stress: 15.9 vs 37.9 MPa; displacement: 0.329 vs 0.168 mm). Therefore, the SHS + cannulated screw has superior biomechanical stability than 3 cannulated screws, and is recommended following anatomic reduction to treat valgus-compacted femoral neck fractures.

Total cross-sectional area of the femoral neck nutrient foramina measured to assess arterial vascular beds in the femoral head.

BACKGROUND: A detailed understanding of the blood supply to the femoral head is required to plan the surgery in the femoral neck and head area. However, information about the blood vessel networks in the femoral head is inadequate. METHODS: The surface of the femoral neck of 100 dry cadaveric adult femur specimens was scanned using a 3D scanner. The scanning distance was 200 mm, precision 0.01 mm, and measuring point 0.04 mm. The images were acquired at a resolution of 1,310,000 pixels. Digital imaging data were recorded from the femoral neck surface. The diameters of the nutrient foramina of the superior, inferior and anterior retinacular arteries, and the ligamentum teres arteries were determined and divided into five groups. RESULTS: The mean cumulative cross-sectional area of the nutrient foramina was as follows: canals of the superior, inferior, anterior, and ligamentum retinacular arteries were 15.59 mm2, 3.63 mm2, 4.32 mm2, and 1.58 mm2, respectively. Next, we analyzed the canals of the superior, inferior, anterior and ligamentum retinacular arteries, respectively, via 3D scanner. We found that the canals of the superior retinacular arteries appear to supply more blood to the femoral head than the canals of the other three types of arteries. CONCLUSIONS: Our results demonstrated that surgeries of the femoral neck and femoral head will be improved with prior 3D scanning and lead to better outcomes in surgeries involving the hip area.

[General anatomy and image reconstruction analysis of the proximal femoral trabecular structures].

OBJECTIVE: To investigate the three-dimensional structure of proximal femoral trabeculae, analyze the formation mechanism, and explore its relationship with the occurrence and treatment of proximal femoral fractures. METHODS: Six cadaver adult femur specimens were harvested and the gross specimens containing both trabecular system and cortical bone were established by hand scraping. All samples were scanned by micro-CT and the CT images were input into Mimics18.0 software to establish the digital proximal femoral model containing trabecular structure. The spatial distribution of trabecular system was observed, and the relations between trabecular bone and the proximal femur surface and related anatomical landmarks were analyzed in digital models. RESULTS: The gross specimen and digital models of trabecular system were successfully established. The trabecular system of proximal femur could be divided into two groups: the horizontal and vertical trabecular. The horizontal trabecular arose from the base of greater trochanter, gone along the direction of femoral neck, and terminated at the center of femoral head. The vertical trabecular began from the base of lesser trochanter and femoral calcar, gone radically upward, and reached the femoral head. The average distance of the horizontal trabecular to the greater trochanter was 22.66 mm (range, 17.3-26.8 mm). In the femoral head, the horizontal trabecula and the vertical trabecula were fused into a kind of sphere, and the distances from the horizontal trabecula to the surface of the femoral head vary in different sections. The average distance of trabecular ball to the femoral head surface was 6.88 mm (range, 6.3-7.2 mm) in sagittal plane, 6.32 mm (range, 5.8-7.6 mm) in coronal plane, and 6.30 mm (range, 5.6-6.3 mm) in cross section. The vertical and horizontal trabeculae intersect obliquely, and the average angle of horizontal trabecular and vertical one was 140.67° (range, 129-150°). CONCLUSION: The trabecular system exhibits a unique spatial configuration, which is the main internal support of proximal femur. Restoration of the integrity of trabecular structure is the important goal of proximal femoral fractures.

Number and distribution of nutrient foramina within the femoral neck and their relationship to the retinacula of Weitbrecht: an anatomical study.

Precise knowledge of the vascular supply of the femoral head is critical when contemplating surgery around the femoral head and neck junction. To determine the blood supply to the femoral neck, 2417 nutrient foramina from 76 cadaveric specimens were analyzed based on size, number, and distribution. Within the subcapital, transcervical, and basicervical regions of the femoral neck, the largest numbers of nutrient foramina were found on the superior (lateral) surface, followed by the anterior and posterior surfaces, and then the inferior (medial) surface (all p < 0.001). The diameters of most of the nutrient foramina were less than 1 mm. For the posterior and superior surfaces, the nutrient foramina in the basicervical region were significantly larger than those within the transcervical or subcapital regions (nutrient foramina >2 mm posteriorly: 23.6, 12.7, and 9.0 % in the basicervical, transcervical, and subcapital regions, respectively; superiorly: 23.7 vs. 15.4 vs. 16.8 %, respectively). In conclusion, neither the anterior nor the inferior surfaces in the basicervical, transcervical, and subcapital regions showed any significant differences in nutrient foraminal size. The areas containing densely distributed nutrient foramina were consistent with the regions covered by the retinacula of Weitbrecht.

Association between injury to the retinacula of Weitbrecht and femoral neck fractures: anatomical and clinical observations.

Currently, there is no objective indicator for surgical procedures in elderly patients with femoral neck fractures. The purpose of this study was to determine the severity of damage to the retinacula of Weitbrecht based on the type of femoral neck fracture, anatomical and clinical observations. Data from 44 patients treated with artificial femoral head replacement were analyzed for the association between Garden type fracture and severity of injury to Weitbrecht's retinacula. Additionally, 18 cases (Pauwels type III fracture) after Watson-Jones surgical approach and internal fixations were used to investigate the bone healing and femoral head necrosis. Among 44 patients (Garden type was III-IV, 79.6%), significant associations were found between Garden type fracture and lateral (P < 0.001), anterior (P = 0.045), and medial (P = 0.004) retinacular injury. Significant positive Spearman correlation coefficients between Garden type and the severity of injury to Weitbrecht's retinacula were Ρ = 0.561 with P < 0.001 for lateral, Ρ = 0.338 with P = 0.025 for anterior, and Ρ = 0.469 with P = 0.001 for medial retinacula. Additionally, 4 out of 18 Pauwels type III fracture cases were observed severe damages on Weitbrecht's retinacula and resulting bone necrosis. In conclusion, this study provided the anatomical and histological correlations between fracture displacement and degree of retinacula injury.