Thumb Hypoplasia
Finger/thumb hypoplasia is when a baby is born with a finger or thumb that is not developed completely (it is usually small in size). Finger/thumb aplasia is when a baby is born without a finger or thumb (it is missing). The condition may or may not involve the other structures of the finger/thumb (bones, tendons, ligaments, muscles, joints and nerves).
Why Choose US
Education Experience
I earned my MD in Surgery from Huazhong University of Science and Technology in Wuhan, China, in 2003. Later, I completed my PhD at Katholieke Universiteit Leuven in Belgium in 2008.
Professional Experience
I am currently an Associate Professor and Chief Physician of Hand Surgery at Wuhan Union Medical College Hospital. I supervise master's students and serve on the editorial boards of several journals, including the Chinese Journal of Experimental Surgery, the Journal of Foot and Ankle Surgery, and the Chinese Journal of Microsurgery.
Expertise
My expertise includes performing syndactyly release using the Pelnac artificial dermal substitute, which eliminates the need for skin grafting. This work was published in the Journal of Plastic, Reconstructive & Aesthetic Surgery in September 2023.
How Is Finger/Thumb Hypoplasia or Aplasia Treated
Treatment of finger/thumb hypoplasia or aplasia varies and may include surgery.
It is important to take into account the child's overall health, medical history and whether surgery will improve how the hand works.
Infants and children born with these hand differences learn to use their hands to pinch and grasp using the structures of the hand they do have. Some activities are still harder for these children to perform.
If surgery is recommended:
It is usually reconstructive (rebuilding or remaking) surgery.
Surgery may be done to make the web space (skin between the fingers or thumb and fingers) less tight. Sometimes a skin graft is needed.
Surgery may be performed on bones, tendons, ligaments, muscles, joints and/or nerves.
The surgery will be done in the operating room under general anesthesia (the child is put to sleep).
Pollicization is a surgery in which the index finger is taken and put in the place where there is no thumb, or there is a small thumb that does not work normally. A hand with a thumb and three fingers usually works much better than a hand with four fingers. It is also harder to see the hand difference when the child has a thumb. The index finger must work well for the surgery to be successful. Pollicization surgery has been done for many years with much success.
After surgery:
After surgery, your child's hand will have bandages and most likely there will be a cast placed over the bandages.
Depending on how much needs to be done, and how long the surgery takes, your child will most likely need to spend at least one night in the hospital.
Why choose child's finger/thumb hypoplasia or aplasia?
Our Hand and Upper Extremity Program team provides a comprehensive, multidisciplinary approach to the care of your child. This means you have access to leading specialists from multiple departments who work together to treat your child.
Your child's care team includes pediatric experts from orthopedic surgery, rehabilitation and physical medicine, and occupational therapy.
There are several types of thumb hypoplasia and aplasia. Your child's symptoms will depend on what type they have.
Five types of thumb hypoplasia. In type 1, the thumb is smaller. In type 2, the thumb has abnormal muscles. In type 3A, the muscles of the thumb are absent. In type 3B, the bones of the thumb are abnormal. In type 4, the bones of the thumb are absent. In type 5, the thumb is completely absent.
Type 1: The thumb is slightly smaller than normal, but all of its structures - the bones, tendons, ligaments, muscles, and joints - are normal. Children with this type of thumb hypoplasia do not typically need surgery.
Type 2: The thumb is small and there are often minor abnormalities in the tendons and muscles within the thumb. The bones of the thumb are small and the middle joint of the thumb is unstable. The thumb may therefore wobble. Because the web space between the thumb and index finger is tight, the thumb has limited movement. Thumb reconstruction surgery may be recommended to improve the strength of the thumb.
Type 3: The bones of the thumb are small, and there are abnormalities in many or all of the muscles of the thumb along with a range of problems in the joints of the thumb. The web space between the thumb and index finger is tight and limits movement. Depending on the stability of the thumb, either a thumb reconstruction or index pollicization is generally recommended.
Type 4: The thumb has no bony support and is attached to the hand by only skin and soft tissue. Index pollicization surgery is generally recommended.
Type 5: The thumb is missing altogether. Index pollicization surgery may be recommended.
Diagnosis & Treatments of Thumb Hypoplasia
How are thumb hypoplasia and aplasia diagnosed?
Thumb hypoplasia and aplasia are usually seen during a baby's first newborn exam. Your child's doctor will look for other deformities that are sometimes associated with this condition. Your child's doctor may order an X-ray so they can look at the structures of your child's thumb. They may order other tests if they suspect another condition.
How are thumb hypoplasia and aplasia treated?
The decision about whether or not thumb hypoplasia or aplasia should be treated is not always straightforward. Children adapt and can function with a missing finger. If untreated, children who have no use of a thumb can learn to pinch objects using their long and index fingers. But they may have problems with pinch strength as well as activities that require holding larger objects. Surgeries for thumb hypoplasia are designed to help with these issues.
Your child's treatment may include one or more of the following:
Occupational therapy
If your child has a mild case of thumb hypoplasia and their thumb is slightly short or weak, or if the web space between their thumb and index finger is slightly tight and prevents mobility, occupational therapy will help them adapt. If your child has surgery, occupational therapy will be essential after the surgery to maximize results.
Thumb reconstruction surgery
This surgery reconstructs the ligaments in the thumb to stabilize the middle joint and improve function and stability by transferring a tendon from another part of the hand. It may also involve an operation to release the tight web space between the thumb and index finger using a skin graft.
Thumb reconstruction can be done when your child is 1 year old or up through when they are school-age.
Index pollicization surgery
This surgery may be an option if your child has no thumb or severe hypoplasia. The operation involves creating a functional thumb by transferring another finger (usually the index finger) to the thumb position.
If there are no other pressing medical concerns that need to be addressed, pollicization surgery is generally performed when your child is between 6 to 18 months old.
If the thumb is completely missing, index pollicization surgery moves the index finger into the thumb position. The index finger is separated at the growth plate, a section of the finger is removed from the hand, and the remaining finger is relocated to where it can serve as a thumb.
After surgery or occupational therapy, your child's thumb should function very well, although some differences in strength and appearance are common.
There are a multiplicity of congenital conditions resulting in hypoplasia or absence of a child's thumb. These include:
Symbrachydactyly, hypoplasia with webbed interconnection of the digits
Cleft hand, with a variety of presentations including a split in the hand, fused metacarpals, transverse phalanges, underdeveloped digits or central polydactyly
Duplicate (polydactylous) thumb
Radial hypogenesis or agenesis, with underdevelopment of the radial side of the forearm, wrist, hand and thumb
Isolated hypoplasia or aplasia of the thumb
Each of these conditions provides a challenge for developing thumb opposition and, therefore, functional prehension in the developing child. At Cleveland Clinic, decades of experience in managing the spectrum of these conditions have enabled us to develop multiple techniques to achieve prehensile hand function in patients requiring an opposable thumb or a thumb positioned in opposition to which other fingers can converge to grasp and pinch.
In all cases, the goal for opposed prehension is positioning a thumb pronated 90 degrees from the broad plane of the hand, palmarly abducted 45 degrees from the hand, and able to cross the midline of the palm with a wide and adequately deep first webspace. From this position, even a thumb acting as a rigid post can provide a very precise and sensate tip pinch and chuck pinch by bringing the ulnar digits to its distal end.
Ideally, however, the ability of the thumb to flex, extend, abduct and actively oppose can be achieved in many cases. Our experience has enabled us to develop techniques for reconstruction of thumbs previously believed to be unreconstructible. In those that are truly unreconstructible, we can convert a healthy index finger into a mobile, opposable, functional thumb through refinement of prior techniques of pollicization.
Reconstruction techniques
Creation of a functional, mobile, stable opposable thumb requires appropriate skeletal substance and support; stable carpometacarpal (CMC) and MP joints; flexion, extension, abduction and opposition motors; appropriate thumb positioning; and an adequately wide and deep first webspace.
In types I and II conditions, this will require stabilization of the MP joint through augmentation of the ulnar collateral ligament with suture imbrication of the capsule and either an abductor digiti minimi (ADM) (Huber) or flexor digitorum superficialis (FDS) opponensplasty through an ulnar sling. In these cases, usually there is an existing extrinsic flexor and extensor.
Type III conditions usually require transfer of bone. At Cleveland Clinic, we have been highly successful in transferring one or two autologous second-toe proximal phalanges, harvested extraperiosteally, to create a metacarpal as well as a carpal receptacle/capsular pouch to create a CMC joint. The joint is sutured around the base of the most proximal transferred toe phalanx. This has been performed with minimal to no complication at the donor site. All physeal plates are preserved with their periosteal sheath. At the same time, a Z-plasty widening and deepening of the first webspace is performed to position the new thumb anatomically. Through the Z-plasty incision, a capsulorrhaphy/collateral ligament imbrication is performed.
These reconstructions are held with one or two fine K-wires and appropriate thumb position in a long arm cast for six weeks. At that point, the cast and K-wires are removed in office, and a soft splint is fabricated from foam material and used for support for another month.
Six months after the initial surgery, secondary surgery is performed, which generally includes Huber opponensplasty, transfer of the ring superficialis flexor tendon for flexor pollicis longus function, and transfer of extensor indicis proprius tendon for extensor pollicis longus function.
Surgery in children as young as six months
Precise timing for initiation of surgical intervention in thumb hypoplasia has been debated. However, with our extensive congenital hand reconstruction experience, we have found that the earlier we can safely begin intervention, the more readily the child incorporates their new hand function into everyday activities. Some surgeons have recommended waiting until the child is as old as age 5 or 6, but this appears to be due to surgeons' comfort with operating on larger structures.
We must remember that hands are the “antennae” of the developing child. Children use their hands to explore their universe and manipulate objects. As they demonstrate developmental milestones, the brain's cerebral cortex develops an image of the hand and thumb and incorporates experiences into enhancing hand function.
We have found that commencing reconstruction of thumb function is most effective as early in development as possible. Ideally, this includes assessment shortly after birth, with the first stages of surgery as early as six months following full gestation. As surgical intervention may require more than one stage, our goal is to provide a child with a working, functional thumb before they begin preschool.
We follow patients throughout childhood to ensure maintenance of function while assessing their need for education, rehabilitation or surgical adjustments. Secondary surgery is required only occasionally.
Our patients have demonstrated exceptionally fine prehensile skills and effective function. They have participated in and mastered activities including sports, musical instrument performance, the arts and skilled technical endeavors throughout childhood and beyond.
FAQ
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