The application of the 150° oblique tangential fluoroscopic view to detect the posterosuperior femoral neck screw in-out-in intraoperatively

Intraoperative angulation of the C-arm for X-ray of each curved surface of the femoral neck wall: a cadaveric study

BACKGROUND

C-arm fluoroscopy is the main method assisting surgical reduction and internal fixation of the femoral neck, as traditional anteroposterior and lateral fluoroscopy is insufficient for visualizing the irregular anatomical structure of the femoral neck. We analysed the anatomy of the femoral neck to ascertain the optimal position and angle of the C-arm for adequate visualization of the femoral neck during fluoroscopy.

METHODS

The femoral neck was divided into anterior, posterosuperior and posteroinferior surfaces. These surfaces and the coronal plane of the femur formed the anterior surface coronal angle (ACA), posterosuperior surface coronal angle (PSCA) and posteroinferior surface coronal angle (PICA), respectively. Three angles of 32 dried femoral samples were measured. In the aluminium model, steel wires penetrated the femoral neck wall, whereas, in the wire model, three Kirschner wires penetrated the femoral neck wall. The C-arm was rotated 5° for a 0°-180° fluoroscopic view of each curved surface. Each specimen was imaged, totalling 111 frames. The optimal angle for fluoroscopic imaging of each surface was ascertained, and fluoroscopic features of the Kirschner wire penetrating the femoral neck cortex at three different angles on fluoroscopy and anteroposterior and lateral radiographs were observed.

RESULTS

The femoral neck is irregularly shaped and cylindrical, with the anterior surface longer than the posteroinferior surface. The ACA, PSCA and PICA were 31 ± 4.589°, 67.813 ± 5.052° and 168.688 ± 3.206°, respectively. The optimal angles for visualizing the anterior, posterosuperior and posteroinferior surfaces of the steel wire aluminium foil model under fluoroscopy were 30.781 ± 5.464°, 67.969 ± 3.721°, and 167.813 ± 4.319°, respectively. There was no significant difference in the measurements of the corresponding surface coronal angles (P > 0.05). Kirschner wires penetrating the femoral neck wall were difficult to visualize on traditional anteroposterior and lateral films. Increasing the angle to 30°, 70° or 170° for fluoroscopy allowed clear visualization of Kirschner wires penetrating the femoral cortex.

CONCLUSION

Traditional anteroposterior and lateral fluoroscopic views are insufficient for clear visualization of the true structure of the femoral neck. Additionally, increasing the angle to 30°, 70° or 170° for fluoroscopy allows observation of the fracture reduction quality from the anterior surface, posterosuperior surface and posteroinferior surface of the femoral neck and the damage to the corresponding cortical bone caused by internal fixation.

LEVEL OF EVIDENCE

Level II.

Association between surgical delays for femoral neck fractures and early postoperative complications in young and middle-aged adults: A study based on the national inpatient sample database

BACKGROUND

Femoral neck fractures (FNF) in young and middle-aged adults are primarily caused by high-energy injuries in traffic accidents. Surgical delays often occur due to transportation issues, preoperative evaluations, and economic burdens.

METHODS

A retrospective analysis was conducted on young and middle-aged FNF patients undergoing reduction and internal fixation surgeries from 2010 to 2019 with the use of the National Inpatient Sample database. Logistic regression analysis was used to assess the relationship between surgical delays and complications, and the independent risk factors contributing to delays. Categorical variables were investigated via a chi-square test, while continuous variables including Elixhauser Comorbidity Index (ECI) scores, length of hospital stay (LOS), and total medical costs were analyzed via t-test or rank-sum test.

RESULTS

9,204 patients undergoing reduction and internal fixation surgeries were included. In the delayed group, patients had higher ECI scores, longer hospital stays, higher expenses, and increased inpatient mortality (1.61% vs. 0.28 %, P < 0.0001). Longer surgical delays were associated with higher risks of complications, including femoral head osteonecrosis, internal fixation loosening and breakage, and respiratory complications. Fluid and electrolyte disorders, metastatic cancer, pulmonary circulation disorders, and renal failure were identified as independent risk factors for surgical delays. Except for anemia (OR=2.37, P < 0.0001), no significant differences in early postoperative complications were found between open-reduction and closed-reduction internal fixation (ORIF/CRIF) surgeries.

CONCLUSION

Early surgical intervention, within a 2-days period after injury, seems to be crucial for young adults with FNF. If CRIF is challenging in some cases, ORIF can be another choice.

Statistical fragility of randomized clinical trials pertaining to femoral neck fractures

OBJECTIVE

P values were frequently misused and misinterpreted, the fragility index (FI) has been utilized to evaluate the robustness of randomized controlled trials (RCTs) as a complement to p-values. This study aimed to assess the statistical robustness of RCTs for femoral neck fractures through the utilization of the FI.

METHODS

We systematically reviewed PubMed, Cochrane Library, and Embase database to identify RCTs pertaining to femoral neck fractures published in the top 25 highest-impact orthopaedic journals and 4 high-impact general medical journals from January 1, 2000, to December 31, 2022. The FI was calculated for the dichotomous, categorical study outcomes in the identified RCTs using the Fisher exact test, with previously published methods. Spearman correlation analyses were used to evaluate potential associated factors associated with the FI.

RESULTS

We identified 10 eligible RCTs with a median total sample size of 101 (IQR, 79.5 to 174.75) and a number of patients lost to follow-up of 19.5 (IQR, 4.5 to 28). The median FI was 3.5 (IQR, 1 to 14.25), implying that reversal of outcome in only 4 patients was sufficient to alter trial significance. The FI was less than the number of patients lost to follow-up in seven (70%) RCTs. P values were negatively associated with the FI, while the number of patients lost to follow-up and patients enroled were not statistically significantly associated with the FI.

CONCLUSIONS

The RCTs pertaining to femoral neck fractures were not as statistically robust as previously thought and should be interpreted with caution. We recommend that the orthopaedic RCT report FI as a supplement for the P values to help readers draw reliable conclusions based on the fragility of the outcomes.

Biomechanical and clinical evaluation of interlocking hip screw in Pauwels Ⅲ femoral neck fractures: A comparison with inverted triangle cannulated screws

Purpose: To compare biomechanical and clinical properties of the novel internal fixation Interlocking Hip Screw (IHS) and conventional inverted triangle cannulated screws (ITCS) for treatment of Pauwels Ⅲ femoral neck fractures. Methods: Twenty synthetic femurs were osteotomized to simulate 70° Pauwels Ⅲ femoral neck fractures and randomly divided into two groups: Group IHS and Group ITCS. Specimens were loaded in quasi-static ramped and cyclical compression testing in 25° adduction to analyze for axial stiffness, failure load, and interfragmentary displacement. 21 matched patients with Pauwels Ⅲ femoral neck fracture who received closed reduction and internal fixation from January 2020 to January 2021 in both Group IHS and Group ITCS. Demographic data, time to surgery, operating duration, intraoperative blood loss, number of fluoroscopies, length of hospital stay, fracture healing time, Harris Hip Score (HHS), the score of Visual Analogue Scale (VAS) and complications such as nonunion, avascular necrosis, and femoral neck shortening were compared. Results: All specimens in the two groups survived in the axial and cyclical compression test. The axial stiffness was significantly higher for Group IHS (277.80 ± 26.58 N/mm) versus Group ITCS (205.33 ± 10.46 N/mm), p < 0.05. The maximum failure loading in Group IHS performed significantly higher than in Group ITCS (1,400.48 ± 71.60 N versus 996.76 ± 49.73 N, p < 0.05). The interfragmentary displacement of the cyclic loading test for Groups IHS and Group ITCS was 1.15 ± 0.11 mm and 1.89 ± 0.14 mm, respectively, p < 0.05. No significant difference was found in terms of demographic data, time to surgery, intraoperative blood loss, length of hospital stay and the occurrence of nonunion and avascular necrosis between groups. Shorter operating duration and fewer intraoperative fluoroscopic views were noticed using IHS compare to ITCS, p < 0.05. The HHS was 72.14 ± 5.76 and 86.62 ± 5.01 in Group IHS, and was 67.29 ± 5.27 and 81.76 ± 5.13 in Group ITCS at 3-month and 6-month follow-up, respectively, p < 0.05. The magnitude of femoral neck shortening was significantly lower in Group IHS compared to Group ITCS (4.80 ± 1.03 mm versus 5.56 ± 1.21 mm, p < 0.05). Conclusion: Our study demonstrated that IHS provided better biomechanical and clinical performance due to its unique biological and biomechanical mechanisms, compared with ITCS. Thus, IHS is a feasible alternative to ITCS for the fixation of Pauwels Ⅲ femoral neck fractures.