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Objective <p>To compare the finite element performance, biomechanical properties, and short-term clinical outcomes of a novel Sliding Cannulated Screw System (SCSS) versus conventional Three Cannulated Screws (3CS) for unstable Pauwels type Ⅲ femoral neck fractures, and to provide an alternative reference for individualized clinical surgical decision-making.</p> Methods <p>(1) Finite element analysis (FEA): A Pauwels type Ⅲ femoral neck fracture model (60° angle) with a 7.5&#xa0;mm medial bone defect was constructed. Three fixation constructs were compared: 3CS, SCSS without medial support screw (SCSS-NS), and SCSS with medial support screw (SCSS-S). Stress distribution and displacement were evaluated under vertical, torsional, physiological force-line, and extreme loads. (2) Biomechanical tests: Nine osteoporotic Sawbone artificial femurs were randomly assigned to three groups. Axial stiffness, torsional stiffness, fatigue displacement, and ultimate failure load were tested using a material testing system. (3) Clinical study: A retrospective controlled study was conducted on 19 patients with Pauwels type Ⅲ femoral neck fractures (July 2023–July 2024): 7 in the SCSS group and 12 in the 3CS group. Perioperative parameters, femoral neck shortening length, Harris hip score (HHS), and complications were compared with 12-month follow-up.</p> Results <p>(1) FEA: Under all four loading conditions, SCSS-NS and SCSS-S groups showed lower maximum femoral head stress than the 3CS group. SCSS-S exhibited lower maximum internal fixator stress and femoral displacement than SCSS-NS. Specifically, SCSS-S reduced femoral stress by 19.4–69.9% and internal fixator stress by 8.0–14.0% under vertical, force line, and extreme loads compared with 3CS; under 30N·m torsional load, femoral stress was 23.4% lower, while internal fixator stress increased by 22.5%. (2) Biomechanical tests: No significant difference in axial stiffness (F = 2.514, <i>P</i> = 0.161) or ultimate load (F = 0.444, <i>P</i> = 0.661) was observed among the three groups, but SCSS-S had the highest axial stiffness (394.20 ± 45.60 N/mm) and ultimate load (1836.80 ± 381.62 N). Torsional stiffness of SCSS-S (0.67 ± 0.08 Nm/°) was significantly higher than that of 3CS (<i>P</i> = 0.030, 95% CI [0.023, 0.357]) and SCSS-NS (<i>P</i> = 0.003, 95% CI [0.153, 0.487]) (F = 17.526, <i>P</i> = 0.003). (3) Clinical outcomes: Baseline data were comparable between groups (<i>P</i> &gt; 0.05). The SCSS group had longer operation time, more intraoperative blood loss, and longer incision (all <i>P</i> &lt; 0.001), but similar hospital stay and cost (<i>P</i> &gt; 0.05). At 12-month follow-up, the SCSS group had higher Harris hip score (92.57 ± 7.16 vs. 76.00 ± 19.45, Z = 2.149, <i>P</i> = 0.046; mean difference [95% CI]: 16.57 [0.30, 32.84]), less femoral neck shortening (2.39 ± 5.14&#xa0;mm vs. 7.03 ± 3.90&#xa0;mm, t =  − 2.233, <i>P</i> = 0.039; mean difference [95% CI]: 4.65 [0.26, 9.04]), and a lower complication rate (14.29% vs. 83.33%, <i>P</i> = 0.006; OR [95% CI]: 0.033 [0.002, 0.451]) compared with the 3CS group.</p> Conclusion <p>The novel SCSS with medial transverse support screw optimizes stress distribution, enhances rotational stability, and limits fracture displacement while retaining dynamic compression. It shows favorable applicability for unstable Pauwels type Ⅲ femoral neck fractures with medial bone defect or senile osteoporosis. Despite longer operation time and greater intraoperative blood loss, SCSS improved postoperative hip function, reduced femoral neck shortening, and decreased fixator-related complications in this small 19-patient cohort. Therefore, it may serve as a viable alternative for eligible patients, pending further validation via large-scale clinical trials.</p>

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Fixation efficacy of a sliding cannulated screw system for unstable Pauwels type III femoral neck fractures: a finite element analysis, biomechanical investigation, and clinical study

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年8月5日

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  • Dandong Li,
  • Yang Luo,
  • Dong Zhang,
  • Xiaopei Yang,
  • Binbin Liu,
  • Ye Peng,
  • Shuwei Zhang,
  • Lihai Zhang

摘要

Objective

To compare the finite element performance, biomechanical properties, and short-term clinical outcomes of a novel Sliding Cannulated Screw System (SCSS) versus conventional Three Cannulated Screws (3CS) for unstable Pauwels type Ⅲ femoral neck fractures, and to provide an alternative reference for individualized clinical surgical decision-making.

Methods

(1) Finite element analysis (FEA): A Pauwels type Ⅲ femoral neck fracture model (60° angle) with a 7.5 mm medial bone defect was constructed. Three fixation constructs were compared: 3CS, SCSS without medial support screw (SCSS-NS), and SCSS with medial support screw (SCSS-S). Stress distribution and displacement were evaluated under vertical, torsional, physiological force-line, and extreme loads. (2) Biomechanical tests: Nine osteoporotic Sawbone artificial femurs were randomly assigned to three groups. Axial stiffness, torsional stiffness, fatigue displacement, and ultimate failure load were tested using a material testing system. (3) Clinical study: A retrospective controlled study was conducted on 19 patients with Pauwels type Ⅲ femoral neck fractures (July 2023–July 2024): 7 in the SCSS group and 12 in the 3CS group. Perioperative parameters, femoral neck shortening length, Harris hip score (HHS), and complications were compared with 12-month follow-up.

Results

(1) FEA: Under all four loading conditions, SCSS-NS and SCSS-S groups showed lower maximum femoral head stress than the 3CS group. SCSS-S exhibited lower maximum internal fixator stress and femoral displacement than SCSS-NS. Specifically, SCSS-S reduced femoral stress by 19.4–69.9% and internal fixator stress by 8.0–14.0% under vertical, force line, and extreme loads compared with 3CS; under 30N·m torsional load, femoral stress was 23.4% lower, while internal fixator stress increased by 22.5%. (2) Biomechanical tests: No significant difference in axial stiffness (F = 2.514, P = 0.161) or ultimate load (F = 0.444, P = 0.661) was observed among the three groups, but SCSS-S had the highest axial stiffness (394.20 ± 45.60 N/mm) and ultimate load (1836.80 ± 381.62 N). Torsional stiffness of SCSS-S (0.67 ± 0.08 Nm/°) was significantly higher than that of 3CS (P = 0.030, 95% CI [0.023, 0.357]) and SCSS-NS (P = 0.003, 95% CI [0.153, 0.487]) (F = 17.526, P = 0.003). (3) Clinical outcomes: Baseline data were comparable between groups (P > 0.05). The SCSS group had longer operation time, more intraoperative blood loss, and longer incision (all P < 0.001), but similar hospital stay and cost (P > 0.05). At 12-month follow-up, the SCSS group had higher Harris hip score (92.57 ± 7.16 vs. 76.00 ± 19.45, Z = 2.149, P = 0.046; mean difference [95% CI]: 16.57 [0.30, 32.84]), less femoral neck shortening (2.39 ± 5.14 mm vs. 7.03 ± 3.90 mm, t =  − 2.233, P = 0.039; mean difference [95% CI]: 4.65 [0.26, 9.04]), and a lower complication rate (14.29% vs. 83.33%, P = 0.006; OR [95% CI]: 0.033 [0.002, 0.451]) compared with the 3CS group.

Conclusion

The novel SCSS with medial transverse support screw optimizes stress distribution, enhances rotational stability, and limits fracture displacement while retaining dynamic compression. It shows favorable applicability for unstable Pauwels type Ⅲ femoral neck fractures with medial bone defect or senile osteoporosis. Despite longer operation time and greater intraoperative blood loss, SCSS improved postoperative hip function, reduced femoral neck shortening, and decreased fixator-related complications in this small 19-patient cohort. Therefore, it may serve as a viable alternative for eligible patients, pending further validation via large-scale clinical trials.