Friday, June 21, 2013

The Future of Prosthetics??

A National Public Radio (NPR) story has brought attention to 3-D printing and the world of prosthetics.

Prosthetic limbs are tricky for any age patient and especially for children.  First, prosthetics are expensive and the growing child needs new prosthetics on a regular basis due to growth.  Second, prosthetics can be a challenge to use.  Kids typically have basic prosthetics (in part due to cost) rather than some of the fancier prosthetics that we have come to see on TV related to the recent wars.  The technology of this new level of prosthetics is amazing.  Kids, however, rarely if ever have access to this type of prosthetic.  The final issue is sensation.  Prosthetics do not have feeling and often kids are more comfortable and more functional with their natural limb (of differing lengths and presence/ absence of fingers) than they are with a prosthetic limb that does have feeling.  A recent study pooled a large number of kids from different Shriners Hospitals and questioned the routine use of prosthetics in kids.  Michelle James, MD, at the Northern California Shriners Hospital led this impactful study.

Recently, technology has provided a low cost prosthetic option.  As the story above details, Makerbot is the company the makes a 3-D printer.
This printer is not cheap (I believe around $2500) but it can make inexpensive prosthetics (reportedly less than 150 dollars).  The following link shows the Robohand which is made on the 3-D printer- the plans for such devices are either free or very inexpensive as detailed.

These prosthetic hands are really exciting because they are inexpensive, can be remade when the child grows, and they do offer functional abilities.  However, because of the lack of feeling, the child must be watching to use the hand.  This prosthetic depends on wrist motion to power the digits (so that if you extend the wrist- bend backward- the fingers flex- make a fist.  If you bend the wrist down, the fingers extend).  These are still very early times with such prosthetics and it is really exciting to dream about what the future will bring.

I was lucky enough today to meet a family working on the Robohand.  The following pictures show the parts which were made for < 10 dollars.  The prosthesis is still being made but I can't  express how exciting this was to see and hold.  Dad had access to the 3D printer at work, got the plans online, and made the parts...
Robohand with pieces outlining hand.

3D printer at Washington University.  Note the spool of Blue and Black material which is the printed substance (shown prior to preparation via machine)

A second 3D printer at Washington University. 

Wednesday, June 19, 2013

Traumatic Madelungs Deformity

Madelungs is a deformity of the wrist related to abnormal growth.  It is typically an inherited condition but may appear without any family members being affected.  I just realized that I have not posted on this condition and will blog more on the topic soon.  Today I want to write about one variety of Madelungs- the traumatic type.

Sometimes Madelungs deformity is related to trauma- an injury to the growth plate of the distal radius.  There can be a variety of different causes but a typical fracture that injuries the growth plate is most common.    In these cases, there is usually a clear fracture and, in a delayed fashion, the Madelungs deformity will appear because of abnormal growth of the radius.  The ulna (pinky sided wrist bone) become notable.  The wrist "sags" and pain may develop.  These pictures tell the story.

Acquired Madelungs deformity.  Note the bump on the ulna related to its normal growth with abnormal growth of the radius.

Note the sag of the wrist in Madelungs.

From a top down view, the wrist looks generally fairly normal in Madelungs.

The x-rays also tell the tale.  The radius is short and has an abnormal appearance.  The ulna is long and prominent.
In this case of Madelungs, the bone on the left (the ulna) is longer than the bone on the right (the radius).  That corresponds with the pictures.

As usual, there can be 2 issues: appearance and function.  We always worry more about function and in this case there can be decreased wrist motion and forearm motion and there may be pain.  If so, we consider treatment.  However, those with Madelungs do also complain about the appearance.  This wrist is not as severe as some but was bad enough to the patient and family for surgery.  The wrist was painful and interfered with activities.

More to come soon on all types of Madelungs.

Wednesday, June 5, 2013

Camptodactyly, Unusual Cause

Camptodactyly is a flexion deformity of the finger, typically the small finger, and is typically caused by an imbalance between the flexors and extensors of the PIP joint.  There have been a number of specific causes identified including abnormal muscle insertion, a tight flexor digitorum superficialis tendon, and weak extensor tendons.  Most patients with camptodactyly have good function because flexion of the finger(s) is maintained (i.e., they can make a good fist).  Sometimes, however, the lack of finger straightening can be a problem during function, especially if the position of flexion is severe (and if severe, the flexed finger can interfere with holding objects in the palm).  Camptodactyly is difficult to "fix" and therapy is often considered the best option.  Surgery is reserved for patients that fail therapy and have real functional limitations.

Congenital conditions, including camptodactyly, are uncommon.  Despite the rarity of conditions such as camptodactyly, there are accepted patterns, causes, and treatments as noted above.  However, there can be an exceptionally unusual cause of any congenital condition which requires a different treatment approach and will change expected outcomes.  For example, bony outgrowths can cause a camptodactyly appearance.

Dysplasia epiphysealis hemimelica (DEH) is more commonly called Trevor disease.  It is a rare, developmental disorder which affects the growth plates of the body's long bones (technically the epiphysis of the bone).  It most commonly affects the knee or ankle but is exceedingly rare even there.  Recently, I was able to treat a 6 month old patient who seemed to have Trevor disease of the hand causing an appearance of camptodactyly.   Osteochondroma (bony tumor which is benign) may be the most common cause of blocked joint extension.  In the case below in a 6 month old child, surgical excision immediately allowed improved motion.

Young patient with camptodactyly caused by a bony growth.

Another view of camptodactyly caused by bony outgrowth.

The finger cannot be extended in this case of camptodactyly.

These x-rays of camptodactyly demonstrate an unusual appearance of the PIP joint of the ring finger, caused by the bony outgrowth.

A side view of camptodactyly finger.  Note the deformity of the PIP joint.  The bony growth is clearly visible and is blocking the ability of the finger to straighten.  

Tuesday, June 4, 2013

Clinodactyly Minimally Invasive Treatment

Clinodactyly is defined as a deviation of a finger.  Most commonly, it involves the 5th finger curved towards the ring finger but can also involve the thumb or any other finger.  We have reviewed clinodactyly previously

In an established clinodactyly in an older child, treatment is based on functional limitations.  Therapy has never been proven successful and typically surgery is indicated.  As previously discussed, osteotomy, or cutting the bone, is the accepted surgery although all different kinds of osteotomies can be considered.

In younger children there is another choice for the treatment of clinodactyly, a physiolysis.  This procedure is simple in that it divides the abnormal growth plate to allow resumption of normal growth.  We reviewed this technique in a previously written journal article .  The procedure was first reported in 1987 by David Vickers from Australia and the best report of a number of kids is from Quebec Canada in 2002

We prefer to perform this procedure in younger children (ideally less than 3 but up to 5 or 6 years of age)- this gives maximal time for growth to allow gradual deformity correction.  One nice thing about this procedure is that it has a quick recovery and doe not require pinning or prolonged immobilization.  And it works, although it takes time to see correction.

Severe clinodactyly in a 1 year old.

While a bit difficult to see, clinodactyly identified with needle prior to procedure.

Severe clinodactyly treated with physiolysis.  The knife is dividing and excising a portion of the abnormal growth plate.