Elsevier

Injury

Volume 47, Issue 12, December 2016, Pages 2749-2754
Injury

Where is the true location of the femoral piriform fossa?

https://doi.org/10.1016/j.injury.2016.10.016Get rights and content

Abstract

Objective

To analyze knowledge of the anatomic location of the piriform fossa using a questionnaire with anatomic figures.

Materials and methods

Participants taking AO Trauma Brasil courses were requested to complete a questionnaire containing a photograph of the superior surface and a photograph of the lateral surface of the femur and answer a question asking which of four numbered points corresponded to the piriform fossa.

Results

Just 4.5% of respondents correctly chose point 2 (the piriform fossa) in both images, while 75.4% of respondents chose point 4 (the trochanteric fossa) as the correct anatomic structure. The subset of 4th-year residents’ answers was significantly different from those of the other subsets, with 7.5% of correct answers.

Conclusions

The low rate of correct answers indicates a tendency for the respondents to be influenced by illustrations in text books or examples in scientific publications that indicate the site of the piriform fossa incorrectly. Interest in the specialty of traumatology is possibly the reason why the subset of 4th-year residents had a better- than-average rate of correct answers.

Introduction

Antegrade intramedullary nailing is currently the first-choice procedure for treatment of fractures of the neck and shaft of the femur [1], [2], [3], [4], [5], [6]. Use of an intramedullary nail was originally introduced by Küntscher, who proposed that the point of entry for straight nails should be the greater trochanter. Later, Winquist recommended that the piriform fossa was a better point of entry in order to avoid problems attributed to insertion via the trochanter, including complications such as comminuted fractures, eccentric reaming of the medial cortex and varus deformity [7], [8], [9], [10], [11], [12].

Despite the importance of the correct insertion point to surgeons who perform anterograde intramedullary nailing procedures, the literature lacks clarity and consensus on terminology. Anatomic references employed include “tip of the greater trochanter,” “piriform fossa,” “trochanteric fossa,” “digital fossa” and “junction of femoral neck and trochanter”1, [13], [14], [15], [16]. The majority of articles recommend the “piriform fossa” as the site for insertion of the anterograde intramedullary nail. However, their illustrations show the “trochanteric fossa” [1], [7], [8], [9], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26].

The objective of this study was to analyze anatomic knowledge about the piriform fossa in a sample of participants taking trauma courses, using an illustrated questionnaire.

Section snippets

Materials and methods

Between January and December of 2014, during Basic Principles and Advanced courses run by AO Trauma Brasil, course participants were requested to complete a questionnaire with the following information, age; and year of residency, or, if not a resident, the time since qualification; and to indicate the location of the piriform fossa on two illustrations. These figures consisted of one photograph of the superior surface and another of the lateral surface of a femur on which four regions had been

Results

Analysis of the relationships between respondents’ answers for the image showing the superior view of the trochanter and the type of respondent (shown in Table 3) revealed that for all subsets the percentage of respondents who correctly answered point 2 (the piriform fossa) was small and that the majority chose point 4 (the trochanteric fossa). There was a significant difference between the frequencies of answers between different subsets of respondents (chi-square test p-value = 0.010).

Discussion

The piriform fossa is an anatomic “structure” that is difficult to identify, particularly during orthopedic surgery to insert an intramedullary nail into the femur. Analysis of our results shows that correct identification of the location of the piriform fossa was infrequent. This could be because of a lack of anatomic knowledge or because the respondents have been induced to error by literature containing incorrect terminology and/or illustrations.

The piriform fossa is an extracapsular area of

Conclusions

The low rate of correct answers indicates a tendency for the respondents to be influenced by illustrations in text books or examples in scientific publications that indicate the site of the piriform fossa incorrectly. Our findings strongly recommend a more consistent anatomy training in medical school and residency, as well as revision of the ilustrations in text books and papers correctly indicating the true femoral piriform fossa.

Interest in the specialty of traumatology is probably the

Conflict of interest

The authors have no conflicts of interest to disclose.

Ethical approval

All procedures were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Financial disclosure

The authors have no financial relationships relevant to this article to disclose.

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