If the buds of the embryo do not develop properly during early pregnancy, various malformations can develop. Different terms are used for the malformations, including deformities and birth defects, referring to malformations that are already occurring during embryonic development.
Many orthopedic malformations can be detected before birth with ultrasound. In that way, appropriate diagnosis and treatment can start early after childbirth, which improves chances of healing. What all deformities have in common is that they can be found in a variety of degrees of severity, from mild shortening to severe shortening to total absence of the affected bone.
Fibular hemimelia and congenital femoral deficiency (CFD) can occur predominantly on their own or in combination. Both primarily affect the bones but also affect the tendons, ligaments, and joints. It is important to remember that although there is a clear treatment algorithm, every patient is slightly different and special. Treatment is therefore still individual and must be adapted to the needs and circumstances of every patient and family.
Fibular hemimelia affects the calf with shortening of the tibia and dysplasia of the fibula. The fibula can be either underdeveloped to different degrees or completely absent. Usually, only one leg is affected; rarely, both legs are affected. In addition, curvature of the leg, instability in the knee joint, and malposition and/or malformations of the foot are often present.
In mild cases, the shorter limb can be lengthened using a six-axis external fixator. In more severe cases, the additional malformations on the knee joint, ankle, and foot must be corrected to ensure good function of the leg and joints.
Congenital Femoral Deficiency (CFD)
In the case of congenital femoral deficiency, the femur (thigh bone) is either shortened to varying degrees or partially absent. It occurs relatively rarely and usually affects only one side. If the hip and knee are intact and stable, simple limb lengthening can be performed.
If ligaments are missing in the knee, the knee is stabilized during the lengthening with a fixator to avoid dislocation. In cases of more severe instability of the knee joint, surgery to improve stability and function is often necessary. The hip might also be malformed. If the hip ball is not well covered by the acetabulum (hip socket) with resulting instability, pelvic surgery might be necessary before bone lengthening can be started. When the frame is removed after lengthening of the femur using external fixation, the bone is stabilized with a nail to protect the bone.
Tibial hemimelia is the rarest of the congenital abnormalities and primarily affects the tibia (shin bone).
If the tibia is partially present, it can be lengthened surgically. If the tibia is absent, the fibula can perform both functions. In severe cases, when not only the tibia but also muscles, tendons, and ligaments are missing, an amputation and prosthetic management might need to be discussed.
Congenital Pseudarthrosis of the Tibia (CPT)
In contrast to the above-mentioned malformations, congenital pseudarthrosis (non-united fractures) of the tibia (shin bone) becomes noticeable only when the child begins to walk. It appears as a curvature of the tibia (shin bone), which becomes more severe as it grows, and a fracture that does not heal.
This disorder is rare, is a special form of pseudoarthrosis, and often occurs together with neurofibromatosis. I recommend that therapy begins as soon as possible after diagnosis to avoid impairments of the ankle, muscles, ligaments, and tendons. Surgical correction includes resecting the non-healing area of the bone and the adjacent periosteum and creating a fusion (union) between the tibia and fibula to prevent refracture. After surgery, the bone is stabilized with a plate or external fixator.
An intramedullary (IM) nail is placed during surgery to additionally stabilize and protect the bone. This nail needs to be changed from time to time during growth.