Measurement of Tip Apex Distance and Migration of Lag Screws and Novel Blade Screw Used for the Fixation of Intertrochanteric Fractures - Fig 1

<p>(a) Blade Screw DHS (ODRC Dynamic Hip Screw System, Chin Bone Corp., Taiwan; US FDA 510(k): K103015). (b) Radiographs of an 101 years-old woman showing fixation with a Blade Screw DHS post-operation. (c) The design and components of Blade Screw DHS.</p

A femoral head test model was fixed in the HIPS system and subjected to multi-axial loading.

<p>A femoral head test model was fixed in the HIPS system and subjected to multi-axial loading.</p

(a) Size of a test block; (b) Cellular rigid polyurethane foam (Type 1522–11) used to simulate a mild osteoporotic bone; (c) Open-cell rigid polyurethane foam (Type 1522–524) used to simulate a severely osteoporotic bone.

<p>(a) Size of a test block; (b) Cellular rigid polyurethane foam (Type 1522–11) used to simulate a mild osteoporotic bone; (c) Open-cell rigid polyurethane foam (Type 1522–524) used to simulate a severely osteoporotic bone.</p

(a) Specimen after lag screw excessive migration (≥10 mm); (b) TAD values of the Blade Screw and traditional DHS groups immediately after surgery and at 3-months follow-up.

<p>(a) Specimen after lag screw excessive migration (≥10 mm); (b) TAD values of the Blade Screw and traditional DHS groups immediately after surgery and at 3-months follow-up.</p

Fracture patterns and displacement behaviors in BP and DCC configurations.

Axial Failure Test Results—DCC Configuration: Before the test, (a), and after the test, (A). Axial Failure Test Results—BP Configuration: Before the test, (b), and after the test, (B). Torsional Failure Test Results—DCC Configuration: Before the test, (c), and after the test, (C). No displacement at the osteotomy site was observed. Instead, a spiral femur shaft bony fracture occurred proximal to the end of the locking plate, with only minimal displacement observed at the osteotomy site. Torsional Failure Test Results—BP Configuration: Before the test, (d), and after the test, (D).</p

Sawbone models.

Sawbone models of the two different configurations of medial distal femur close-wedge osteotomy (A) Biplanar Distal Femur Osteotomy (BP DFO) and (B) Double Chevron-Cut DFO (DCC DFO).</p

Overview of the test protocols.

ObjectiveThis study aimed to compare the stability and mechanical properties of the double chevron-cut (DCC) and biplanar (BP) distal femoral osteotomy (DFO) techniques, along with analyzing their respective contact surface areas.MethodsBiomechanical testing was performed using sawbone and 3D modeling techniques to assess axial and torsional stability, torsional stiffness, and maximum torque of both osteotomy configurations. Additionally, 3D models of the sawbone femur were created to calculate and compare the contact surface area of the DCC, BP, and conventional single-plane DFO techniques.ResultsAxial stiffness and maximum strength did not significantly differ between the two osteotomy techniques. However, in terms of torsional properties, the DCC technique exhibited superior torsional stiffness compared to the BP group (27 ± 7.7 Nm/° vs. 4.5 ± 1.5 Nm/°, p = 0.008). Although the difference in maximum torque did not reach statistical significance (63 ± 10.6 vs. 56 ± 12.1, p = 0.87), it is noteworthy that the DCC group sawbone model exhibited fracture in the shaft region instead of at the osteotomy site. Therefore, the actual maximum torque of the DCC construct may not be accurately reflected by the numerical values obtained in this study. The contact surface area analysis revealed that the BP configuration had the largest contact surface area, 111% larger than that of the single-plane configuration. but 60% of it relied on the less reliable axial cut. Conversely, the DCC osteotomy offered a 31% larger contact surface area than the single-plane configuration, with both surfaces being weight-bearing.ConclusionThe DCC osteotomy exhibited superior mechanical stability, showing improved rotational stiffness and maximum torque when compared to the BP osteotomy. Although the BP osteotomy resulted in a larger contact surface area than the DCC osteotomy, both were larger than the conventional single-plane configuration. In clinical practice, both the DCC and BP techniques should be evaluated based on patient-specific characteristics and surgical goals.</div

The test set-up used in the study.

On the left, a schematic diagram depicts the configuration, while on the right, a corresponding photograph is displayed. The sawbone femur is subjected to loading using an Instron E10000 testing machine (Instron, Canton, MA, USA).</p

3D model analysis of contact surface area.

Left: DCC Model—The contact surface area measured 1749 mm2. Right: BP Model—The transverse cut had a contact surface area of 1129 mm2, and the axial cut had a contact surface area of 1698 mm2.</p

S1 File -

ObjectiveThis study aimed to compare the stability and mechanical properties of the double chevron-cut (DCC) and biplanar (BP) distal femoral osteotomy (DFO) techniques, along with analyzing their respective contact surface areas.MethodsBiomechanical testing was performed using sawbone and 3D modeling techniques to assess axial and torsional stability, torsional stiffness, and maximum torque of both osteotomy configurations. Additionally, 3D models of the sawbone femur were created to calculate and compare the contact surface area of the DCC, BP, and conventional single-plane DFO techniques.ResultsAxial stiffness and maximum strength did not significantly differ between the two osteotomy techniques. However, in terms of torsional properties, the DCC technique exhibited superior torsional stiffness compared to the BP group (27 ± 7.7 Nm/° vs. 4.5 ± 1.5 Nm/°, p = 0.008). Although the difference in maximum torque did not reach statistical significance (63 ± 10.6 vs. 56 ± 12.1, p = 0.87), it is noteworthy that the DCC group sawbone model exhibited fracture in the shaft region instead of at the osteotomy site. Therefore, the actual maximum torque of the DCC construct may not be accurately reflected by the numerical values obtained in this study. The contact surface area analysis revealed that the BP configuration had the largest contact surface area, 111% larger than that of the single-plane configuration. but 60% of it relied on the less reliable axial cut. Conversely, the DCC osteotomy offered a 31% larger contact surface area than the single-plane configuration, with both surfaces being weight-bearing.ConclusionThe DCC osteotomy exhibited superior mechanical stability, showing improved rotational stiffness and maximum torque when compared to the BP osteotomy. Although the BP osteotomy resulted in a larger contact surface area than the DCC osteotomy, both were larger than the conventional single-plane configuration. In clinical practice, both the DCC and BP techniques should be evaluated based on patient-specific characteristics and surgical goals.</div