The role of postoperative piriformis fossa and greater trochanter tubercle distance to predict cutout failure after cephalomedullary nail fixation - Background, Methods, Results, and Conclusion

Q: What does the study measure to predict cutout failure after CMN fixation?

It measures the postoperative distance (dPG) from the deepest point of the piriformis fossa to the most lateral greater trochanter tubercle, comparing the injured side with the contralateral uninjured hip.

Q: How were patients and outcomes assessed in the clinical part of the study?

From 2005 to 2010, 311 intertrochanteric fracture patients underwent CMN fixation. Postoperative 2-year follow-up outcomes were reviewed, including union, cutout failure, osteonecrosis, and nonunion.

Q: What key finding links dPG to lag screw cutout failure?

dPG was significantly higher in the cutout failure group, and for every 1 mm increment in dPG, the odds ratio for lag screw cutout increased substantially, with dPG also showing diagnostic performance via ROC analysis.

Sep 29, 2026

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Background: This study examined whether the postoperative piriformis fossa to greater trochanter tubercle distance (dPG) is associated with lag screw cutout failure after cephalomedullary nail fixation for intertrochanter fractures. A rotating femur model evaluated how PG changes during femur rotation. Methods: Records from 311 ITF patients treated with CMN (2005-2010) were reviewed, comparing dPG in patients with and without cutout failure. Results: Higher dPG increased cutout odds and showed good diagnostic performance; correlation patterns were demonstrated in the model. Conclusion: Increased dPG is a risk factor and may aid radiographic prediction alongside TAD, fracture displacement, and reduction quality.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Abstract

1. Introduction

Background and rationale

Methods

Results

Conclusion

J Chin MedAssoc Original article The role of postoperative piriformis fossa and greater trochanter tubercle distance to predict cutout failure after cephalomedullary nail fixation Derming Tiena,b, Wen-Chieh Changa,b, Ming-Fai Chenga,b, Kuei-Hsiang Hsua,b, Yu-Ping Sua,b,* aDepartment of Orthopaedics and Traumatology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; bDepartment of Orthopaedics, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC Abstract Background: This study investigated the association between postoperative piriformis fossa and greater trochanter tubercle distance (distance from the deepest point of piriformis fossa to the most lateral greater trochanter tubercle [PG]) and cutout failure after cephalomedullary nail (CMN) osteosynthesis for intertrochanter fracture (ITF) . A rotating femur model was designed to analyze PG variation during femur rotation. Methods: From 2005 to 2010, 311 patients diagnosed of ITF (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association [AO/OTA] 31-A2 and A3) underwent CMN fixation at our institute were reviewed. Of these, 281 (90 .3%) patients achieved union without complication, 21 (6 .8%) had cutout failure, six (1 .9%) had femoral head osteonecrosis, and three (1%) had nonunion during postoperative 2-year follow-up. The side difference of postoperative PG compared to contralateral uninjured hip (dPG) was analyzed between patients who had cutout failure and those who did not. In the rotating femur model, the PG was measured for every 2.5° increments of internal and external rotation from 0° to 50° . Results: The dPG was significantly higher in the failure group (10 .2 ± 4.2 vs 6.6 ± 3.5 mm, p <0 .001) . The odds ratio for lag screw cutout was 6.35 (95% CI, 1.10-11.6, p =0 .003) for every 1 mm dPG increment. dPG exhibited high diagnostic performance in predicting cutout failure according to receiver operating characteristic curve analysis. The area under the curve was 0.774 (95% CI, 0.711-0.837) . dPG yielded the greatest sensitivity (78 .4%) and specificity (78 .4%) to predict lag screw cutout when cutoff value being 8.65 mm. In rotating femur model, PG change from baseline demonstrated significant (p <0 .001) positive and negative correlation with increased external and internal rotation, respectively. Conclusion: Increased dPG is a risk factor of cutout failure for ITF osteosynthesis with CMN. In conjunction with tip-apex distance, fracture displacement, and reduction quality; dPG can help surgeons interpret postoperative radiograph and predict failure. However, it should be noticed that a proper and standard patient positioning is critical for accurate dPG measurement. Keywords: Femoral head; Odds ratio; Radiology; Receiver operating characteristic; Risk factors 1. INTRODUCTION Intertrochanteric fracture (ITF) of the femur remains as one of the leading burdens on the health care system as the average population grows more elderly.1,2 The surgical outcome and patient survival can be negatively affected by patients’ comorbidities and osteoporotic status. Moreover, unstable ITFs distinguished by lateral wall fractures, medial calcar fragmentation, or reverse oblique fracture pattern can lead to increased postoperative complications and mortality.3 * Address correspondence. Dr. Yu-Ping Su, Department of Orthopaedics and Traumatology, Taipei Veterans General Hospital, 201, Section 2, Shi-Pai Road, Taipei 112, Taiwan, ROC. E-mail address: [tvghpo@gmail.com](tvghpo@gmail.com) (Y.-P. Su). Conflicts of interest: Dr Yu-Ping Su, an editorial board member at Journal of the Chinese Medical Association, had no role in the peer review process of or decision to publish this article. The other authors declare that they have no conflicts of interest related to the subject matter or materials discussed in this article. Journal of Chinese Medical Association. (2024) 87: 179-188. Received September 10, 2023; acce

FAQs

What does the study measure to predict cutout failure after CMN fixation?

It measures the postoperative distance (dPG) from the deepest point of the piriformis fossa to the most lateral greater trochanter tubercle, comparing the injured side with the contralateral uninjured hip.

How were patients and outcomes assessed in the clinical part of the study?

From 2005 to 2010, 311 intertrochanteric fracture patients underwent CMN fixation. Postoperative 2-year follow-up outcomes were reviewed, including union, cutout failure, osteonecrosis, and nonunion.

What key finding links dPG to lag screw cutout failure?

dPG was significantly higher in the cutout failure group, and for every 1 mm increment in dPG, the odds ratio for lag screw cutout increased substantially, with dPG also showing diagnostic performance via ROC analysis.

Sep 29, 2026

Upload by Valentina