PubMed 1. Basic - Calcaneo-navicular bar
This is the first in a series of mini-workshops on the subject of using PubMed, the
public Internet interface to the US National Library of Medicine (NLM) Medline database.
For this introduction we are going to pursue the subject raised by Dr Harpal Singh Selhi;
pain and swelling of the ankle in a 17 year old soccer player whose Xrays show evidence of
a calcaneo-navicular bar.
This workshop is overly simple for those who are used to using PubMed. It is basic and
is aimed at people who rarely use the site. More complex functions of the site will be
examined in future workshops.
The Medline computer database was started in 1967 and consists of citations, abstracts
and subject classification information for all published articles in thousands of medical
and bioscience journals including over 100 orthopaedic journals. PubMed is a search engine
which allows this database to be searched via an Internet interface. It is important to
understand some of the limitations - only abstracts are online at the site, not full text;
there are many orthopaedic journals which are not indexed in Medline (example, the
Bulletin of the AAOS); textbooks and the Internet are not searched by PubMed; and an
important part of the system, classification of subject matter is done by librarians, not
orthopaedic surgeons. For these reasons, a PubMed search may not be as complete or
accurate as you might like.
Another cause for concern is that PubMed searches commonly return hundreds or thousands
of citations, making it very difficult to identify the material you would like to examine
more fully, and even more difficult to be sure that you have done a comprehensive search.
These workshops are designed to identify the processes involved in conducting a search, to
describe the more valuable features of the site and to formulate strategies which will
make searching more satisfying.
The easiest URL to remember is http://pubmed.gov
However, this address forwards you to http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed
which is probably the one to bookmark. Open the site and type the subject
(calcaneo-navicular bar) into the search box. Then click on Go
The list of citations is disappointing. There are only two articles listed, both are
nearly 40 years out of date and neither have an abstract which would allow us to get an
idea of the contents. We will examine why this is a poorly chosen search string
at the end of this workshop.
However, all is not lost. Beside each citation is a link to "Related
Articles". These are articles in the Medline database which have a subject
classification (entered by the librarians) close to the subject classification of the
original article. So if an article in 1967 was classified as being on the subject of
flatfeet all subsequent articles which are classified similarly will be
"Related". To see how the index article has been classified you can change the
display from the default (Summary) to "Citation"
|1: J Bone
Joint Surg Br. 1967 May;49(2):281-7.
Excision of calcaneo-navicular bar for painful spasmodic flat foot.
Mitchell GP, Gibson JM.
- Child, Preschool
- Follow-Up Studies
PMID: 6026513 [PubMed - indexed for MEDLINE]
- Child, Preschool
- Follow-Up Studies
- Middle Aged
- Postoperative Care
- Preoperative Care
- Time Factors
|The list of MeSH terms (above) includes three on flatfoot. The two terms
marked with an asterisk * are the major subjects of the article. MeSH stands for Medical
Subject Heading and is the vocabulary used by NLM librarians to describe the contents of
articles. Click on the link to Related
Articles You will see a much more promising collection of 144 articles (below). If you
look at the citation of the second article (left) you can see that it is indeed classified
in a very similar fashion to the first.
However, although there are more articles in this list and more recent ones, we see
that many of them are about flatfeet in general, not tarsal coalition. The best plan is to
go down through the list until you find an article which is relatively recent and exactly
on the subject. I selected # 19 from the title and from the fact that it is an article in
the JAAOS which is accessible online to all Fellows and International Members of the AAOS.
Since membership also gets you free admission to the annual meeting and a free practice
website this is one of the all-time bargains in academic orthopaedics. I read this article
and it is an excellent review and summary of the problem. He advocates excision of the
calcaneo-navicular bar and interposition of extensor digitorum brevis muscle to prevent
recurrence. (80% good outcomes)
The author name line is a link to a page displaying the abstract of that article.
|J Am Acad
Orthop Surg. 1998 Sep-Oct;6(5):274-81.
- Tarsal coalition and painful flatfoot.
Shriners Hospital for Children, Portland, Oregon and Department of Orthopedics, Oregon
Health Sciences University, Portland, OR 97201-3905, USA.
The prevalence of tarsal coalition is probably 1% or less. The two sites most commonly
affected are the calcaneonavicular joint and the middle facet of the talocalcaneal joint.
Diagnosis should be suspected in the preteen or teenage patient with insidious or sudden
onset of pain in the midfoot to hindfoot associated with a lack of motion in the subtalar
joint. Initial treatment with immobilization or an orthosis may relieve symptoms, but most
patients will have persistent symptoms that warrant surgical correction. Long-term results
indicate that excision of the coalition is moderately successful in relieving symptoms in
the calcaneonavicular bar. Long-term success with excision of subtalar bars is less clear,
although early relief of symptoms is usually possible.
Now that we are satisfied that this is an article which is on subject and up to date we
can expand the search repeating the use of the "Related Articles" link. This
gives you a much longer list (over 300) and all of the first 20 appear to be on subject.
If our object with this basic search was to find something about the topic we have been
There is a clue here about why our initial search was disappointing. "Tarsal
coalition" is used commonly in these articles, the word "calcaneonavicular"
more rarely and "calcaneo-navicular" very rarely. The computer robot is very
literal and doesn't "know" that these terms are the same unless someone in the
NLM has told it so. We would have done better to use tarsal coalition as the initial
search string. As we go further into this subject we can see that using standard
terminology to define your subject has even more definite advantages.
Why did the related
articles link on Vincent's article yield a better collection than "related
links" for the original 1967 Mitchell and Gibson article? The reason is that the
librarians introduced a new classification term, Foot
Deformities, Congenital in 1988. Vincent's article was classified under that subject
as well as flatfeet giving a more accurate description of the subject. This is the reason
I suggest using the most relevant and the most up to date article you can find,
for the "Related Articles" link.
PubMed is not the only database that can be searched. PubMed Central (PMC) is a
database of articles of which the full text is available for free. Unfortunately very few
orthopaedic articles are published in journals which make the full text available in this
way. If you search PMC for tarsal coalition there are no articles. A search for the MeSH
deformities, congenital yields two papers, both on genetics.
Summary for basic steps using PubMed
- Enter your subject in the search box on PubMed (http://pubmed.gov)
- If no suitable articles are found, adjust your search string and enter another commonly
used synonym. You must be prepared to iterate when you use search engines.
- Find an article on subject and look at the abstract. Keep doing this until you find an
article which is on subject and up to date.
- If that is not enough, click on the Related Articles link to find more articles which
are on the same subject.
- Refining the search beyond finding "something" is the subject of future
Please submit any comments and discussion of this to the orthopod list. We will let any
discussion of this workshop die down before going on to the next. Indeed if there is no
discussion and no one urges me to continue, I won't.
Other workshops in this series
Myles Clough firstname.lastname@example.org