Thumb hypoplasia is a spectrum of the defect varies from a working small thumb to total absence of the thumb.
In the normal hand, the tip of the thumb reaches to the middle of the proximal phalanx of the index finger. When the thumb is shorter than this it can be classified as hypoplastic.
Epidemiology
Thumb hypoplasia has an incidence of 1 in 100,000 live births. Both males and females are equally affected. About 60% of cases occur in isolation whereas others are associated with defects of the radius bone.
About 60% of the cases have bilateral involvement and in unilateral cases, right side is affected more than left.
It is crucial to rule out associated abnormalities because often this malformation is a manifestation of a syndrome.
There could be associated abnormalities of the heart, spine, and gastrointestinal tract.
Associated Conditions
- VACTERL or VATER Syndrome
- Holt-Oramthrombocytopenia-absent radius (TAR)
- Fanconi anemia
- Thumb duplication
- Transverse deficiencies
- Symbrachydactyly
- Brachydactyly
- Cleft hand complex
- Ulnar longitudinal deficiency
- Congenital constriction ring syndrome
- Apert syndrome
- Rubinstein–Taybi syndrome
Classification of Thumb Hypoplasia [Blauth]
Type I
This type is mildest form and thumb only has minor hypoplasia. All musculoskeletal and neurovascular components of the digit are present though small in size.
Type II
All of the bony structures are present though may be small. The metacarpophalangeal joint has ulnar collateral ligament instability. There is thenar hypoplasia.
Type IIIA
There are musculotendinous and osseous deficiencies and the carpometacarpal joint is intact. There is an absence of active motion at the metacarpophalangeal joint or interphalangeal joint.
Type IIIB
This is similar to type IIA with an addition of aplasia of the base of metacarpal and there is deficient carpometacarpal joint.
Type IV
It is also called a floating thumb. The remnant of thumb is only attached to hand by the skin and digital neurovascular structures
Type V
Complete absence of the thumb
Presentation of Thumb Hypoplasia
Apart from deformed or shortened thumb, there could be hypoplasia of thenar musculature and absence of skin creases indicating muscle or tendon abnormalities. The metacarpophalangeal joint may be in the abduction. There may be laxity of ulnar collateral ligament and the web space [between index finger and thumb], may be tight. The patient should be examined for radial and ulnar abnormalities as well as for cardiac and abdominal abnormalities.
Grasp and prehension of the thumb are hampered.
Lab Studies
Peripheral blood smear and complete blood count should be done. It is important to rule out Fanconi anemia
Imaging
Apart from routine x-rays of both hands, x-rays of both forearms should be done to rule out any abnormality.
Treatment of Thumb Hypoplasia
The treatment of hypoplastic thumb is guided by stage of thumb hypoplasia and presence of carpometacarpal joint stability.
In type I hypoplasia where augmentation of thumb abduction is not necessary and these patients generally do not need surgical treatment.
Patients with type I thumb hypoplasia with insufficient thumb abduction would need opponensplasty a procedure of tendon transfer for opposition movement of the thumb.
Type II and IIIA thumb hypoplasia need the release of first web space, opposition transfer, stabilization of MCP joint.
Type IIIB, IV, V thumb hypoplasia would require ablation of the existing remnant and pollicization [creation of new thumb by transferring index finger.
The timing of surgery is usually between 6 and 12 months of age.
about floating thumb & if there is any other soluotion rather than pollicization done in this case, thanks.
I had a floating thumb from the time I was born. My parents had decided against having it removed and pollicization. In my case it was the best thing they could have done because I decided to have it removed when I was 11. I am 24 now and I am doing great. I just had it removed with no pollicization. I didn't have problems at all growning up without a thumb. I do have to say that the floating thumb was not on my dominant hand so that could be why I did not have many problems. If you need someone to talk to you are more then welcome to get in contact with me at my email address
Alicia
Hi Alicia and others, our son was born days ago and has floating thumb on his right hand. appreciate if I can share your experiences and knowledge on the treatment. many thanks.
Ronnie
my one month old has vacterls and she had this on her left hand..any options besides pollicization?
@dominique,
Was she evaluated for treatment. Xrays? What did the doctor advise?
If thumb is non functional politicization is the answer.
I am 30 yrs old and was born with floating thumb on my right (and dominate) hand. My mother left it alone and figured science would figure out a way to fix it later or let me decide what to do with it. I learned to write left handed and do just about everything else right handed. I do use my index finger as a thumb in some cases and have developed the ability to stretch it further than most people can. I can even hold a soda can in between my thumb and middle finger. In other cases, with lighter objects, i use my floating thumb as something to hold an object against. I enjoyed being able to twist my thumb around in a circle as a kid and always had a good sense of humor about it. The only thing it held me back from is joining the military and becoming a cop, either of which i couldn't have done even with the "fix". just offering another perspective.
My son was born with floating right thumb, we didn't do anything because we didn't like the idea of policization or removing the toe. he is now 8 and keep on asking why it is small, what can we do to make it big but he also doesn't like both ideas. He learnt to use the left hand but somehow it is bothering him that he was born with a small thumb. Is there anything like donating my big toe or second toe!!!
@Immaculate,
You cannot put someone else's thumb or toe on another person. Not yet!
It would be rejected by his body.
How about offering the tendons to construct his thumb!!!!
@Immaculate,
No
I was born with a floating thumb on my right hand and my parents decided on pollicization. I learnt from a baby how to use it as a normal hand and a lot of people have said it goes unnoticed until pointed out. I am 24 now and pregnant and this is the only time I have had any problems with it, as my hands have swolen I have got carpal tunnel syndrome which is when the hands ache and feel numb and tingly, and it is so much worst and painful in my right hand than the left. I've tried splints but they have no effect, is there anything else I could do to relieve the pain.
Did you see the specialist. Your situation is special as you are pregnant. Depending on severity of the symptoms, you need to be evaluated for the treatment,
I have a 3 year old, born with EA/TEF but no other known VACTERL issues. I have noticed her thumbs lately, and feel they are misshaped. After searching online, found a picture of a child with Type II Hypoplasia that is identical to my child’s hands.
We live in a rural area, not a lot of access to specialists. What kind of oversight or care would I need to pursue, if indeed this is what she has?
Thank you!
Jennifer
Oregon, USA
if it is thumb hypoplasia, you should get her assessed for the required treatment. Photos may appear similar but every case is different and needs evaluation. She is already three years of age. If any procedure is required, it should be planned as well.
Please get an appointment with specialist in spite of the limitations you wrote.
Take care.
Hi Dr
My son is born with right thumb hypoplastic,aged 3 years Doctor considers IIIB is the case. He has no other abnormalities, Vacterl, Fanconi Anemia, TAR ruled out. We do not won’t him to undergo pollicisation.
Just wanted your suggestion on stem cell treatment for missing digits / hand growth how much is the research in this line forward and will this really work out??
I do not think that stem cells can provide clinical benefits. The field needs more research though it is very promising. Clinical uses of stem cells is limited to few conditions and is not common too.