Tibial Hemimelia (TH) manifests as a shortened leg with knee and ankle deformities. Most often those deformities are varus in the ankle and a knee flexion contracture in the knee. There is also typically
instability of these joints due to a lack of collateral ligaments.
The patella and quadriceps muscles may be present or absent but will have
limited function if present. The tibia may be shortened, dysplastic, or absent. The tibia may also present as an anlage—a fibrous remnant that does not appear on x-
rays.
The fibula may be normal or dysplastic and is often dislocated from the knee.
There are usually associated deformities of the foot as well.
Tibial Hemimelia is extremely rare, occurring in only one out of one million live births. It can be diagnosed by ultrasound as early as sixteen weeks gestation.
There have been multiple studies on the genetic mechanisms of
Tibial Hemimelia with reports suggesting parent to child transmission in families with multiple siblings affected.
Tibial Hemimelia is associated with several syndromes: Werner’s syndrome, Tibial Hemimelia-Polysyndactyly-Triphalangeal Thumb Syndrome (THPTTS), and CHARGE syndrome, to name a few.
Tibial Hemimelia can be unilateral or bilateral, with 30% of cases reported bilateral. For some unknown reason, TH seems to favour the
right side (72% of unilateral cases).
In type I Tibial Hemimelia the tibia is completely absent. Depending on the appearance of the distal femoral epiphysis, it is further subdivided
into Type Ia, where the femur is hypoplastic, and Type Ib where the femoral epiphysis is normal.
This latter situation is an indication of the presence of a cartilaginous Tibial anlage and it should be expected to ossify as the child grows.
The proximal epiphysis is preserved with a short segment of tibia; the distal epiphysis is absent.
In this type, the distal epiphysis is present with a short segment of tibia; the proximal epiphysis is absent. This is the least common type of Tibial
Hemimelia, and it has been postulated that a true Type III Tibial Hemimelia does not exist but will transform into Type 1B given time.
The radiographic deformity noted in this patient population is diastasis of the ankle. The fibula is relatively longer and displaced proximally at the knee. This form demonstrates wide variability in
severity and may be diagnosed later in life.
The treatment of Tibial Hemimelia aims to achieve a functional limb equal in length to the normal limb at maturity, with a plantigrade, stable and flexible foot.
Treatment of Tibial Hemimelia should be highly individualized to the patient and undertaken in experienced centres with access to
multidisciplinary teams.
Dr. Soumya Paik has a clinical fellowship in Paediatric Orthopaedics from National University Hospital (NUH), Singapore. He has treated
many a Paediatric Orthopaedics cases successfully. Visit our official website to get more details.
Get treated from Tibial Hemimelia; feel free to call us at “ � or mail us at drsoumyapaik@gmail.com.
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