Joints ... & Lady Gaga

By now you've probably heard - Lady Gaga has cancelled the remainder of her Born This Way Ball Tour due to a hip injury.  Specifically, the issue is reported to be a labral tear at her hip joint, and some sources are speculating this may have been exacerbated by lupus (although it has not been confirmed that she actually has lupus, despite an apparent family history).

We just finished covering joints in my anatomy class, so let's talk about what might have gone down in Our Good Lady's hip, shall we?

Hip Joint Anatomy

The hip joint, also known as the acetabulofemoral joint, is the connection between the bone of the thigh and the pelvis (at the hip bone/os coxa).  Specifically, the head of the femur ("thigh bone") forms a ball and socket joint with the acetabulum (the cup-shaped indentation) of the hip bone, hence the name acetabulofemoral joint.  The hip joint is a synovial joint, which means it has a complex structure that includes supporting tissues, a joint cavity and synovial fluid, and it is also a diarthrosis, which means it is a freely moveable joint.

As a synovial joint, the hip joint is stabilized by a series of structures including ligaments and surrounding muscles.  There is also the labrum, a ring of fibrocartilage that helps the acetabulum (the depression in the hip bone) to grip the femoral head and make dislocation less likely.

Left hip joint, disarticulated

The consensus seems to be that folks who are especially active with their hip joints are at a higher risk of injuring a labrum - ballet dancers keep coming up as a prime example.  While she's not exactly a prima ballerina, I suspect folks who have seen Lady Gaga do her thing would agree she's quite active with her hip joints.  As such, I feel comfortable putting her in a category of folks who are more likely than most to tear a labrum.

When the labrum tears, depending on the severity of the tear symptoms can range from pain and stiffness to loss of mobility at the joint.  The treatment will depend on the severity of damage and the symptoms - for some this may be a course of anti-inflammatory medications and physical therapy, for others this includes surgical intervention.  Lady G falls in the latter category, suggesting her tear was on the more serious end of the spectrum.

Youch.

Lupus & Joint Function

Now for the lupus part.  Lupus erythematosus is a family of autoimmune conditions - "autoimmune" refers to the body's own immune system attacking and damaging/destroying a tissue or organ that it otherwise should leave alone.  As with many autoimmune disorders, the exact cause of lupus is not known.  The tissues/organs it attacks can vary, but one that is often cited is the joints - this often manifests as joint pain and swelling in affected individuals.  One not-so-common lupus-related complication cited in some resources is avascular necrosis, a condition of diminished blood supply to bones resulting in bone tissue death and structural failure of the tissue.  One of the most common areas affected by this complication is the hip joint.

In an interview in 2010, the Lady spoke of a family history of lupus and the fact that she had tested "borderline positive" herself.  Now whether this makes her more likely to experience a labral tear ... yeah, I don't know.  Folks with lupus are more likely to experience inflammation in and around their joints and from the arthritis-related research I've done in the past, joint inflammation can contribute to joint damage.  I have no idea if that includes increased likelihood of cartilage tears.  Given LG's profession and the recognized labrum-associated occupational hazards thereof, I suspect she could well have injured her labrum without the help/exacerbation of a pre-existing joint-related condition.  And as someone who is trained only academically in orthopedics, is not a clinician and did not specialize specifically in joints ... my professional opinion, along with $2, may just get you a cup of coffee.


References

Floyd, R.T., Adams, J.B. (2009) "Chapter 9: The Hip Joint and Pelvic Girdle." Kean University Kinesiology. Retrieved 24 February 2013 from 

http://www.kean.edu/~jeadams/docs/Kinesiology/Kines_Power_Points/Kines_Chap_9.pdf.

"Hip labral tear." (2011) Mayo Clinic. Retrieved 24 February 2013 from http://www.mayoclinic.com/health/hip-labral-tear/DS00920.

"Lupus." (2011) Mayo Clinic. Retrieved 24 February 2013 from http://www.mayoclinic.com/health/lupus/DS00115/.

"Systemic lupus erythematosus." (2012) ADAM Medical Encyclopedia/PubMed Health. Retrieved 24 February 2013 from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001471/.

Dimples

What causes dimples?

A not-uncommon occurrence, when learning anatomy, is to learn something new about a particular part of the body and then wonder how that applies to what you observe on the bodies around you (e.g. your classmates, your family members).  My students have been studying the neck and facial muscles for the past few weeks so it's probably not surprising that someone asked about dimples.

Mario Lopez, known forever to my generation as AC Slater from Saved by the Bell
Also, dimples.

Dimples, shown in the photo above, are a (usually) naturally-occurring indentation in the flesh on a part of the body.  Folks are often most familiar with the facial variety.  I have been fantastically unable to find information detailing the proportion of the population that has them, or I'd throw you that figure here.  

According to the few peer-reviewed papers I was able to find in the medical literature (I was stoked that there were any), there is a correlation between dimples and an anatomical variation in particular facial muscles -- specifically, in the zygomaticus major muscles.

Gray's Anatomy

On each side of the face, the zygomaticus major muscle originates at the zygomatic bone of the face and inserts, effectively, at the corner of the mouth.  When it contracts, it pulls the corner of the mouth in a lateral and superior direction (as in a smile).  Most humans have a single zygomaticus major muscle on each side of the face (as shown in the image above).  Some studies of cadaveric tissue point to an anatomical correlation between having dimples and possessing a bifid (split in 2 parts) zygomaticus major muscle on each side of the face.  This muscle has the same origin and action as the single zygomaticus major, but inserts at 2 points on each side (one above the corner of the mouth, one below the corner of the mouth).  My guess (although I have not found it directly stated) is that the dimple would occur in the space between these 2 parts of the split zygomaticus major.  Some studies suggest that folks with dimples also have connections between the hypodermis and dermis in this region (referred to as "dermal anchoring") which may contribute to the indentation.  Dimple creation surgery seems to mimic such anchoring.

In short, the research points to a connection between dimples and an anatomical variation in one set of facial muscles, possibly accompanied by a variation in the attachment of skin to the underlying tissue.

References

Gassner, H.G., Rafii, A., Young, A., Murakami, C., Moe, K.S., Larrabee, W.F. (2008) Surgical anatomy of the face: implications for modern face-lift techniques. Arch Facial Plast Surg. 10(1): 9-19. doi: 10.1001/archfacial.2007.16.

Pessa, J.E., Zadoo, V.P., Garza, P.A., Adrian, E.K., Dewitt, A.I., Garza, J.R. (1998) Double or bifid zygomaticus major muscle: Anatomy, incidence, and clinical correlation. Clin Anat. 11(5):310-3.  DOI: 10.1002/(SICI)1098-2353(1998)11:5<310::AID-CA3>3.0.CO;2-T

Finding Answers, Part 1

When a student asks a stumpifying question mid-lecture, my first thought is generally, "Huh. I can't believe I haven't wondered that and looked it up by now."  My second thought is often, "I wonder why <insert name of student> didn't look that up him/her/zirself."  In some cases, it's likely that the question just dawned on that student in the midst of lecture and being in the very tech-free classroom that I insist upon, he/she/zie could not at that moment search for the answer and so decided to ask me.  In other cases, it might be that students aren't sure exactly how to go about finding such an answer (or it doesn't occur to them that they could).  Yes, the internet is a glorious treasure-trove of informational wonder ... but how does one parse the pile of links that inevitably result from Googling a topic?  Where else do people look?  Let's talk about this.  Let's talk about this in a series of related posts lest we all become completely overwhelmed.  

Credit for the knowledge I impart in this series goes to the following individuals, who have taught me pretty much all of what I know about informational research:  Yvonne Piper, R.N., M.L.I.S., Patricia Elzie, M.L.I.S., Joel Burton, M.A. and David Patterson, Ph.D.

Okay. So. I vote we start with The Googles.

by Hilariawesome

The default starting point for many folks when looking for answers on the interwebs is to high-tail it over to Google and enter their question/topic.  The upside to this is that these folks will then be deluged with links. The downside to this is ... well, that these folks will then be deluged with links.  Some of them may be informationally-dependable while others may not, and telling the difference can be challenging.  The order in which links fall on the response page says nothing for their informational reliability.  Folks who go the Google Route for answers have a bit of potential legwork ahead of them before they hit paydirt.

If you use Google (or another search engine) to find information, one way to decrease background noise is to be as specific as possible with your search terms.  For example, let's say I'm wondering if there is anatomical variation in biceps brachii muscles (known to many as "biceps"), so I have something on which to blame my poor ability to do biceps curls (sidenote: anyone else ponder this or is it just me?).  If I then head to Google and search using the terms "arm muscles," it's a pretty mixed bag - I get some sites that may have useful information (like anatomy resources) as well as links to fitness magazine sites and some advertisements.  If I make my search terms a bit more specific - "biceps" - then the results, while focused on a particular muscle, look quite similar.

If, however, I get more specific than that - "biceps anatomical variation" - suddenly my results look quite different.  My entire first page of results (except for Google's designated ad space) is a mix of scholarly articles, anatomy atlas references ... and of course there's always a link to a Wikipedia article.  By entering more, specific terms, one often gets a more targeted list of results.  Google Guide has a rather useful page that discusses this in more detail and provides examples. There are also fancy librarian-type search tricks one can use that are detailed in places such as this or presented as a tutorial here - if constructing Boolean search terms sounds like a hot way to spend an evening, this will be right up your alley.

Another option is to use Google Scholar, which searches only from scholarly articles, and if you so choose, patents and legal documents where appropriate.  Starting your search here narrows the sort of results you'll get right off the bat, which also helps to decrease the background noise of personal webpages and folks trying to sell you things. The potential downside is that the results you get may be less user-friendly (read: written for experts in a field for other experts in that field) than those you get from just-plain-Google.

That was long-winded.  High five if you made it all the way through.

In our next installment of Finding Answers, Your Humble Professor tackles how to evaluate the resources that show-up on that search results page. 

Lordosis

What are some medical causes for sway back (lordosis)?

Lordosis, also known as sway back, is an exaggeration of the lumbar curvature of the spine.  Folks are often most familiar with this in reference to the posture of pregnant females.

First things first - let's start with what is anatomically normal.

An anatomically normal human vertebral column has 4 curvatures that can be observed from the lateral view.

The curvatures of the thoracic and sacral regions of the spine are present at birth while those of the cervical and lumbar regions develop postnatally, during the first year of life.

A person who has an exaggerated or excessive lumbar curvature would be said to have hyperlordosis (a.k.a. sway back, saddle back).  Some resources shorthand this to just "lordosis," although that technically refers to the normally-occuring curvature in this area.

There are several reasons a person may experience lordosis.  As I stated earlier, folks who are aware of this may know it best from the posture of pregnant females.  If a person has weight added to the anterior abdomen (as in the case of pregnancy or increased visceral fat in the abdomen), that person may develop lordosis as a result, to stabilize one's center of mass (as depicted in the image below).

Whitcome, et al. (2007) Nature

Other causes noted for lordosis (particularly in children) are achondroplasia and spondylolisthesis, neither of which involves addition of weight to the anterior abdomen and both of which affect the skeleton.  Achondroplasia is a bone growth disorder which causes the most common form of dwarfism, so while folks with this condition may experience lordosis, it likely wouldn't be considered the major symptom of this condition.  Spondylolisthesis is a condition in which a vertebra in the vertebral column slips out of position – this most often happens to L5 - and would then cause a change in the lumbar curvature resulting in lordosis.  There are other conditions a person may have (like forms of muscular dystrophy) that could result in lordosis, but that person would have a lot of other symptoms as well.  

References

"Achondroplasia" (2011) PubMed Health. Retrieved 8 February 2013 from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002544/

"Lordosis" (2012) MedlinePlus. Retrieved 16 January 2013 from

http://www.nlm.nih.gov/medlineplus/ency/article/003278.htm

"Spondylolisthesis" (2012) MedlinePlus. Retrieved 16 January 2013 from

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002240/

Whitcome, K.K., Shapiro, L.J., Lieberman, D.E. (2007) Fetal load and the evolution of lumbar lordosis in bipedal hominins. Nature. 450: 1075-1078. doi: 10.1038/nature06342.