Piriformis Syndrome: A Bibliometric Analysis

Systematic Review and Meta-Analysis
1
Medicine®
Assessment of the piriformis muscle and
piriformis syndrome via Web of Science database
A bibliometric analysis
Sema Polat, PhDa,* , Mahmut Tunç, PhDb, Ufuk Can Aksay, PTa, Elif İpek Sönmez, PhDa, Esin Özşahin, MDc,
Pınar Göker, MDa
Abstract
Background: Piriformis syndrome, which is seen as the cause of 0.3% to 6% of low back pain, is a painful condition that
occurs as a result of compression of the piriformis muscle on the sciatic nerve. Although there are many studies in the literature
about piriformis syndrome, no bibliometric analysis has been found. This study aims to evaluate piriformis syndrome and conduct
a bibliometric analysis of studies related to piriformis muscle and syndrome.
Methods: This study was conducted on March 27, 2024, using data recorded in the Web of Science Core Collection Database.
The search was made as “Topic = Piriformis OR Piriformis Syndrome.” Accordingly, 1345 results were found, and as a result of
the necessary inclusion and exclusion criteria, 961 documents remained. The data was transferred to the VOSviewer software for
further analysis.
Results: 961 documents based on piriformis muscle or piriformis syndrome were obtained. The country with the most
publications was reported to be the USA with 31.42%. Other countries are ranked at around 5% or less. While 9 of the top 10
most cited institutions are based in the USA, clinics that make significant research contributions also attract attention among these
institutions. Journals that publish articles containing piriformis syndrome are prominently surgery, physical therapy, anatomy, and
general medicine journals. The most repeated keywords were reported as piriformis syndrome, diagnosis, pain, muscle, sciatic
nerve, and hip. In contrast, the most repeated clinical terms were reported as approach, surgery, piriformis muscle, injection,
sciatica, and compression.
Conclusion: The findings obtained in this study are thought to be important for understanding to providing literature with new
perspectives on this subject. They will also focus on the missing parts of the subject from this perspective. Also, this study would
provide a novel perspective to the studies about piriformis syndrome and contribute to the researchers about the limits of the
topic, and being aware of the active journals that publish papers on this issue would facilitate the work of the researchers.
Abbreviation: WoS = Web of Science.
Keywords: bibliometric analysis, piriformis syndrome, sciatica
1. Introduction
Piriformis is a pear-shaped muscle located in the gluteal-pelvic
section.[1,2] It helps hip extension, lateral hip rotation, and hip
abduction. It also plays a role in providing hip stabilization.
It may originate from different anatomical regions such as
the pelvic/anterior surface of the sacrum, the level of anterior
sacral foramina 2, 3, and 4, the gluteal surface of the ilium,
the sacrotuberous ligament, and the sacroiliac joint capsule. It
attaches to the apex of the greater trochanter of the femur.[3,4]
The piriformis muscle is innervated by nerve branches origi-
nating from L5, S1, and S2. The branches of the inferior and
superior gluteal artery, internal pudendal artery, and lateral
sacral artery may provide blood supply to the piriformis.[2,3]
Piriformis syndrome is a condition caused by compression
of the sciatic nerve around the ischial tuberosity by the pir-
iformis muscle. Symptoms of piriformis syndrome, which is
often misdiagnosed, include burning pain around the hip,
numbness, and tingling sensations along the distribution of
the sciatic nerve.[2,3] Piriformis syndrome accounts for 0.3%
to 6% of all low back pain and/or sciatica cases.[3] The ana-
tomical relationship between the piriformis muscle and the
sciatic nerve is important in diagnosis of piriformis syndrome.
There may be 6 possible different anatomical relationships
All authors contributed to this article equally.
The authors have no funding and conflicts of interest to disclose.
The datasets generated during and/or analyzed during the current study are
available from the corresponding author on reasonable request.
a Department of Anatomy, Cukurova University Faculty of Medicine, Adana,
Turkey, b Department of Therapy and Rehabilitation, Baskent University, Vocational
School of Health Services, Adana, Turkey, c Department of Anatomy, Baskent
University, University Faculty of Medicine, Adana, Turkey.
* Correspondence: Sema Polat, Department of Anatomy, Cukurova University
Faculty of Medicine, Adana, Turkey (e-mail: [email protected]).
Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.
This is an open-access article distributed under the terms of the Creative Commons
Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to
download, share, remix, transform, and buildup the work provided it is properly
cited. The work cannot be used commercially without permission from the journal.
How to cite this article: Polat S, Tunç M, Aksay UC, Sönmez Eİ, Özşahin E, Göker
P. Assessment of the piriformis muscle and piriformis syndrome via Web of
Science database: A bibliometric analysis. Medicine 2024;103:47(e40416).
Received: 3 June 2024 / Received in final form: 11 October 2024 / Accepted: 17
October 2024
http://dx.doi.org/10.1097/MD.0000000000040416

2
Polat et al. • Medicine (2024) 103:47 Medicine
between the piriformis muscle and the sciatic nerve. In the
rst possibility, the sciatic nerve passes under the piriformis
muscle, in the second possibility, the divided sciatic nerve
passes through and under the muscle, in the third possibility
the divided sciatic nerve passes above and below the muscle,
in the fourth possibility the sciatic nerve passes through the
muscle without division. In the fth possibility, the divided
sciatic nerve passes over and through the muscle. In the sixth
and nal possibility, the sciatic nerve passes between the main
piriformis muscle and a smaller accessory piriformis muscle
with a separate tendon, located under the main piriformis
muscle. Among all these possibilities, the most common one
is the rst possibility.[1] Clinical evaluation and exclusion are
important in the diagnosis. Anamnesis, physical examination,
and imaging methods can be used for diagnosis.[4] These tests
can be applied during physical examination: Freiberg (force-
ful internal rotation of the extended thigh), Pace (resisted
abduction and external rotation of the thigh), Beatty (deep
buttock pain produced by the side-lying patient holding a
exed knee several inches off the table), exion, adduction,
internal rotation. Ultrasound, magnetic resonance imaging,
computed tomography, and electromyography are used to
diagnose piriformis syndrome and differentiate it from other
conditions such as facet arthropathy, herniated nucleus pul-
posus, lumbar muscle strain, and spinal stenosis.[3] In the
clinic, palpation over the Piriformis muscle is one of the most
common methods used to diagnose. In addition, Freiberg and
Pace tests were found to be only 67% positive. With clini-
cal symptoms, signs, and several provocative maneuvers, this
rate can be brought closer to 100%. In clinical practice, phys-
ical examination is often combined with ultrasonographic
assessment of the gluteal region to conrm/exclude the diag-
nosis of piriformis syndrome. Indeed, ultrasound imaging can
be performed in an outpatient setting immediately after the
physical examination; and can be used as a guide to plan/
perform the eventual diagnostic and/or therapeutic injec-
tion. The most common sonographic ndings of piriformis
syndrome are hypoechoic thickening of the fascicles of the
sciatic nerve (fascicular edema) together with “bending” of
the sciatic nerve under the inferior surface of the piriformis
muscle during dynamic ultrasound assessment.[5,6] Treatment
options include short-term rest, muscle relaxants, NSAIDs,
and physical therapy. Physical therapy includes stretching
the piriformis muscle, deep tissue massages, and range of
motion exercises. People may see a decrease in symptoms
with exercise. Continuity of exercise is important to prevent
the problem from recurring. Also, steroid injection around
the piriformis muscle may be useful in reducing inammation
and pain. Surgery should be the last option.[3]
Bibliometric analysis reveals a model that analyzes the
literature to understand current approaches.[7] First used
in 1969, bibliometric analysis has become a science that
includes bibliography, statistics, and mathematics.[8] It is an
approach that enables the quantitative assessment of produc-
tivity in any subject.[9] With bibliometric analysis, detailed
quantitative information can be learned about authors, key-
words, journals, countries, institutions, references, etc in any
research eld.[10]
The need for support in visualizing the data on the subject to
be studied has increased. The use of VOSviewer for bibliometric
analysis has gained importance.[11] VOSviewer is a software tool
for creating and exploring networked maps, created in 2010 by
Nees Jan van Eck and Ludo Waltman.[12] VOSviewer enables the
creation and viewing of bibliometric maps.[12,13]
To date, there have been very few evaluations of research
productivity in the eld of piriformis muscle or piriformis syn-
drome. Moreover, no studies have been conducted using bib-
liometric analysis on this subject. This study aims to analyze
the research productivity of articles about piriformis muscle and
piriformis syndrome.
2. Methods
On March 27, 2024, using the advanced search section in the
Web of Science (WoS) Core Collection database, a search was
made with the “Topic” eld. In this database topic eld is dened
as “search title, abstract, author keywords, and keywords plus.”
Our primary term for this study was piriformis, and we added
the term “piriformis” to the search section. We also used the l-
ter to get the main result. The lter was “Topic = Piriformis OR
Piriformis Syndrome (Should: Search within topic).” The follow-
ing indexes were scanned with WoS Core Collection included;
• Science Citation Index Expanded (1980–present)
• Conference Proceedings Citation Index: Science
(1990–present
• Book Citation Index (2005–present)
• Emerging Sources Citation (2005–present)
Furthermore, the following indexes were scanned with WoS
Core Collection excluded;
• Social Sciences Citation Index (1980–present)
• Art & Humanities Citation Index (1975–present)
• Conference Proceedings Citation Index: Social Science &
Humanities (1990–present)
• Book Citation Index: Social Science & Humanities
(2005–present)
A sum of 1345 documents were reported. In the present
study, only articles, review papers, editorial material, and letter
were included while proceedings papers, early access, meeting
abstracts, book chapters, and reprints were excluded from the
analysis. Furthermore, as inclusion criteria; Articles containing
the word piriformis and articles containing piriformis syndrome.
As an exclusion criteria; Studies in plant science containing the
word piriformis, and studies in animal science containing the
word piriformis were removed. Keywords containing the word
piriformis but not linked to the piriformis muscle were also
removed. As a result, 961 studies were included. With this l-
ter method, articles scanned in WoS and containing piriformis
or piriformis syndrome were reported. All these articles were
exported via “Tab delimited” (windows) le format within “full
recorded and cited references” from 1 document to 961 by
dividing 500 documents. All of this exported data was imported
to the VOSviewer software program (version 1.6.19).[13] With
the Vosviewer software program, the included data was exam-
ined in detail. All research processes are shown in Figure 1. We
also beneted from the WoS core collection database for nd-
ings such as document type or publication year.
2.1. Ethics statement
As the authors, we declare that this study was conducted by
the principles of the World Medical Association Declaration
of Helsinki “Ethical Principles for Medical Research involving
Human Subjects.” In addition, due to the method of this study,
ethics committee approval was not obtained.
3. Results
There were determined 961 documents. The rst document was
from 1981 in the WoS database. Despite of the WoS database
started indexing Science Citation Index Expanded journals
since 1980, only 1 or 2 articles were scanned in WoS till 1989.
Although the number of studies increases from year to year, most
publications were made in 2019. A slight decrease in the number
of publications was noted after 2019. The distribution chart of
publication years accumulated over 4 years is given in Table 1.
According to the data we received from WoS, 79% of the studies
are original articles, followed by 11% reviews and 6% letters
(Fig. 2). When we look at the contributions of the countries to

3
Polat et al. • Medicine (2024) 103:47 www.md-journal.com
the studies on piriformis, it can be seen that the USA comes to
the fore. While the country with the most publications (31.42%)
and most citations (40.92%) was the USA, the other countries
in the top 10 contributed approximately 5% (Table 2). Scientic
network maps of the countries were created with the VOSviewer
program. When the map of countries with at least 10 publica-
tions and at least 100 citations is created, we see that the USA,
Spain, and Italy are in the center. It is also noteworthy that
there are countries from every continent except Africa (Fig. 3).
While 6 of the 10 institutions with the most publications are in
the USA, the other 4 are Toronto University, Iran University of
Medical Sciences, Hacettepe University, and Catholic University
of Korea. Moreover, 9 of the 10 most cited institutions are in the
USA (Table 3). When we examine which journals mostly pub-
lish publications about piriformis, we see that journals based on
rehabilitation, orthopedics, surgery, and anatomy come to the
fore. The most cited publications on piriformis were published
in journals with similar themes, although the journal names
have changed (Table 4). Journals with at least 10 publications
and over 30 citations were mapped using the VOSviewer pro-
gram in Figure 4. Accordingly, 3 separate clusters emerged and
are shown in different colors on the map. The red cluster can
be dened as rehabilitation-focused journals, the blue cluster
as radiology-anatomy-focused journals, and the green cluster
as a surgery-orthopedics-focused cluster. In our study, author
analysis was also made and the author who published the most
was determined to be Fishman LM with 12, followed by other
authors in the top 10 who published mostly 6 or 5. On the other
hand, among the top 10 most published authors, only Fishman
LM stands out in terms of citation (Table 5). Although there
are relatively old publications at the top of the list of the 10
most cited publications, recent publications can be seen towards
the end of the list (Table 6).[14–23] In our study, an analysis was
made on which keywords were chosen and how often the key-
words were repeated. Table 7 shows the top 10 most common
keywords. The most common keyword is piriformis syndrome.
Other keywords in the table appear to be related to piriformis
and piriformis syndrome (Table 7). Moreover, a network map of
keywords was created with the VOSviewer program. According
Figure 1. Research process: detailed methodologic workflow.
Table 1
Distribution of publication years in for 4-years periods.
Publication years (in for 4-yr periods) Publication number
1980–1983 2
1984–1987 2
1988–1991 14
1992–1995 13
1996–1999 36
2000–2003 40
2004–2007 70
2008–2011 152
2012–2015 186
2016–2019 220
2020–2023 219
Figure 2. Distribution of document types.

4
Polat et al. • Medicine (2024) 103:47 Medicine
to Figure 5, it contains 18 keywords which are occurred at least
20 times. It can be seen that 5 clusters are formed in the scien-
tic map. The green cluster is related to the surgery, the purple
cluster is related to sciatica, the blue cluster is related to the
deep gluteal syndrome, the yellow cluster is related to anatomy
and the red is related to pain-rehabilitation. The lines show the
connections of the keywords with each other. Keywords that are
occurred more often have a larger circle size. The keyword with
the largest circle size is piriformis syndrome (Fig. 5). Moreover,
in our study, the most repeated clinical terms in 961 documents
were determined and scientically mapped via VOSviewer
(Table 7; Fig. 6). In addition, the top 5 keywords and clinical
terms of the most common imaging techniques in piriformis
syndrome are shown in Table 8.
4. Discussion
Piriformis syndrome is one of the conditions that causes
sciatica pain. Known mechanisms of formation include
overuse and hypertrophy of the piriformis muscle. It has
been observed that the infrapiriformis foramen narrows
during flexion, adduction, and internal rotation of the
Table 2
Top 10 countries with most documents and citations.
Rank Country Documents Country Citations
1 United State of America 302 (31.42%) United State of America 6308 (40.92%)
2 Turkey 63 (6.55%) Australia 858 (5.56%)
3 Japan 50 (5.20%) Italy 751 (4.87%)
4 Canada 44 (4.57%) Canada 598 (3.87%)
5 India 44 (4.57%) England 582 (3.77%)
6 China 44 (4.57%) Spain 519 (3.36%)
7 South Korea 44 (4.57%) Japan 517 (3.35%)
8 Australia 42 (4.37%) South Korea 508 (3.29%)
9 Spain 39 (4.05%) Germany 424 (2.75%)
10 England 35 (3.64%) Turkey 422 (2.73%)
Figure 3. Countries network map according to documents via VOSviewer software.
Table 3
Top 10 organizations with most documents and citations.
Rank Organization Documents Organization Citations
1University of Toronto 14 Northwestern University 388
2 Hospital of Special Surgery 13 Stanford University 325
3 Mayo Clinic 10 Mayo Clinic 316
4 University of Pittsburgh 10 Institute for Nerve Medicine 307
5 Columbia University 10 Johns Hopkins University 306
6 Catholic University of Korea 9 University of Toronto 285
7 Baylor University 9 New York University 267
8 Hacettepe University 8 University of Michigan 261
9 St Gegorge’s University 8 University of Pittsburgh 240
10 Iran University of Medical Sciences 8 Hospital for Special Surgery 230

5
Polat et al. • Medicine (2024) 103:47 www.md-journal.com
hip. It is also known that the piriformis can be spastic and
inflamed and may even appear as a myofascial syndrome.
Anatomical variations between sciatica and piriformis con-
stitute another cause of the syndrome. Approximately 50%
of cases also include a history of direct trauma to the pelvis
or hip. In addition, the diagnosis of piriformis syndrome can
be used for sciatic problems resulting from nerve trunk com-
pression, such as osteophytes, hematomas, myositis ossif-
icans, pseudoaneurysms, endometriotic cysts in the pelvis,
and prolonged external pressure, regardless of piriformis
involvement. Finally, femoral neck and ischial tuberosity
fractures and hip arthroplasty can also be the cause of sci-
atica problems. These are called secondary piriformis syn-
drome or pseudosciatica.[24,25]
The diagnosis of piriformis syndrome is clinical. Pain in the
hip is detected by applying different physical tests. Pain in the
hip will worsen with exion, adduction, and internal rotation.
On physical examination, tenderness may be observed in the
hip from the medial edge of the greater sciatic foramen to
the greater trochanter. It is stated that the main tenderness is
in the lateral third of the muscle. Therapy involves reducing
inammation, spasms, and pain. For this purpose, anti-inam-
matory drugs, analgesics, and muscle relaxants can be used and
physical therapy can also be applied. If there is no response to
these applications, local injection of anesthetic and cortico-
steroid preparations may be considered. Surgery may only be
considered as a last resort in cases that do not improve with
conservative treatment or injections.[24]
In this bibliometric study, a detailed bibliometric analysis
was carried out on piriformis muscle and piriformis syndrome,
which has increased the number of studies on it signicantly,
especially in the last 20 years. Bibliometric analysis determines
which publications are available in a particular eld and period.
It reveals belong to authors, scientic centers, countries, and
journals these publications.[26] Bibliometric methods can reveal
the references to be used in existing research and reveal missing
points. It also allows complex information to be visualized and
analyzed easily.[27] Bibliometric methods examine publications
in terms of many features to ensure the development of a eld
of interest and to guide future research. Recently, bibliometric
analysis has been used to evaluate research productivity in many
research elds of medicine around the world.[28] No research has
been conducted on piriformis or piriformis syndrome using the
bibliometric analysis method. In this study, we took piriformis
Table 4
Top 10 journal with the most published document and citation.
Rank Journals Documents Journals Citations
1Journal of Arthroplasty 18 Clinical Orthopaedics and Related Research 620
2 Surgical and Radiologic Anatomy 17 Archives of Physical Medicine and Rehabilitation 440
3 Muscle & Nerve 16 Arthroscopy The Journal of Arthroscopic and Related Surgery 413
4 Cureus Journal of Medical Science 16 American Journal of Physical Medicine & Rehabilitation 361
5Clinical Anatomy 13 Journal of Arthroplasty 338
6 Skeletal Radiology 13 Muscle & Nerve 320
7 Clinical Orthopaedics and Related Research 13 Surgical and Radiologic Anatomy 304
8 Journal of Bodywork and Movement Therapies 13 Journal of Bone and Joint Surgery-American Volume 273
9 Archives of Physical Medicine and Rehabilitation 11 Clinical Biomechanics 261
10 Pain Physician 11 Journal of Biomechanics 261
Figure 4. Journals network map according to documents via VOSviewer software.
Table 5
Top 10 author with most published document and citation.
Rank Author Documents Author Citations
1 Fishman, LM 12 Fishman, LM 439
2 Martin, HD 12 Rosner, B 257
3 Tubbs, RS 9 Snijders, CJ 220
4 Palmer, IJ 7 Delp, SL 214
5Chhabra, A 6Hess, WE 214
6 Iwanaga, J 6 Hungerford, DS 214
7 Hopayian, K 6 Jones, LC 214
8Misirlioglu, TO 5 Johnson, JP 204
9 Akgun, K 4 Villablanca, JP 204
10 Bagcier, F 4 Porta, M 202