Within the Trauma Department at our institution, it was decided that surgeons would use TFN® for osteosyntheses of intertrochanteric femoral fractures. The surgeon could choose between a helical blade and femoral neck screw (“lag screw”) for the collum implant. Patients were included if they: i) were older than eighteen years of age, ii) had pre- and postoperative X-ray diagnostics available, and iii) were treated by/under direct supervision of a trauma surgeon. Candidates were excluded if they had a pathologic fracture, prior hip surgery on the ipsilateral side, additional fractures or an incorrectly registered operation code.

The cohort included those identified using the operation code 38535 (femur # intertrochanteric, TFN) from the digital registration system. The study group was comprised of 685 patients with an intertrochanteric femoral fracture treated with a TFN® with helical blade or a TFN® with femoral neck screw between January 1,2012 and December 31, 2016. A total of 631 patients where included in the study; 54 were excluded on the basis of a wrongly registered operation code after reassessment of the preoperative X-ray images (Fig. 1).

The study was approved by the local ethics committee of the Albert Schweitzer Hospital. Signed informed consent forms allowing use of medical records for research purposes were obtained from all patients.

Mechanical complications (e.g., axial migration, axial cutout, lateral cut-out, non-union, periprothestic fracture, unacceptable position, mechanical complications with a tip-apex distance [TAD] <15 mm or >25 mm)413) were obtained from available post-operative X-ray examinations. Axial migration was considered a normal phenomenon due to collapsing of the fracture until sufficient stability was achieved41314). Intervention variables (i.e., TAD, surgery time, position of the collum implant [according to the Cleveland index as shown in Fig. 2]15), weight bearing prescriptions, length of stay, discharge destination after the hospital, postsurgical complications), were obtained from the medical records of electronic patient files. The TAD was calculated (Fig. 3) on the first post-operative X-ray for each patient as described by Baumgaertner et al.14). All measurements were performed by a single investigator, and 10% of his findings were double-checked by a trauma surgeon.

Fractures were classified using the AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification and classified as stable (31-A1) or unstable (31-A2) (Appendix 1)16).

Statistical analysis was performed using Statistic Package for Social Sciences (SPSS) version 24.0 (IBM Corp., Armonk, NY, USA). Differences were considered to be statistically signiflcant when P<0.05. The chi-square test was used to compare differences between the two groups for each variable, and the Student's t-test was used for quantitative variables.

When comparing outcomes associated with the use of helical blades and femoral neck screws for the surgical treatment of intertrochanteric femoral fractures, we observed no statistically significant differences in the frequency of cut-out or other mechanical complications. Axial migration may be an early symptom of cut-out, and in this study, the high number of axial migration events was considered a functional phenomenon as part of the physiological collapse of the fracture to obtain (sufficient) stability and a prerequisite for optimal bone healing. All figures from this study were in accordance with the figures found in recent literature713171819). In our study, the total percentage of mechanical complications (i.e., 6.7%) was lower than what is reported (i.e., 16–23%) in different studies20). One reason for this could be the differentiation within the surgical department. The trauma surgeons operate on greater than 75.3% of the intertrochanteric femoral fractures, thus developing a high level of competence in this type of operation.

For all intervention variables tested, we observed no statistically significant differences among the two treatment groups. An increased risk of mechanical complications according to the literature occurs at a TAD of <15 mm or >25 mm413). The disadvantage of TAD measurements is that they are made using the first postoperative X-ray images. In patients with a TAD of <15 mm or >25 mm, an expectative policy will be maintained with regard to re-operation of the patient and the clinical condition of the patient will lead treatment decisions. The increased risk of mechanical complications described in the literature with a TAD of <15 mm or >25 mm was not observed in this study11421). For the time being, the value of the TAD used in research and how these values are reflective of clinical outcomes remain open for discussion.

This study revealed no difference in postoperative complications between helical blade and femoral neck screws when used to surgically treat intertrochanteric femoral fractures. The actual number of postoperative complications will most likely be much higher since postoperative complications were only identified using data relating to the clinical admission of the patient. Also, postoperative complications are typically underreported and a subset of patients will develop a postoperative complication (e.g., delirium) after discharge from the hospital. Postoperative complications that were treated and resolved during admission and were no longer topical at discharge were often not mentioned in the discharge letter and therefore not reported.

The strengths of this research were that it evaluated patients treated over a five year time frame; all patients who received surgical treatment for an intertrochanteric femoral fracture using a TFN® with helical blade or femoral neck screw were included.

Weaknesses of this research include: i) underreporting of variables that could not be included in the analyses (e.g., blood loss), ii) underreporting of analyzed data, which led to missing data (especially in the registration of postoperative complications), and iii) surgeries were not all performed by the same trauma surgeon. All operators had the skills to place a TFN® with femoralneck screw, however, only three had the skills to place a TFN® with a helical blade; this factor may have possibly influenced the results.