Tibial hemimelia, commonly known as tibial deficiency, is a rare congenital condition that causes the child to be born with a missing or shorter shin bone. Now, this results in quite a considerable difference in the length of the legs of the child and can even cause deformities in the ankle, leg & knee joint.
The cause of Tibial hemimelia is still unknown in most cases, but it sometimes runs in the family. In some extreme cases, amputation is recommended. However, this is the last resort when everything else seems to fail. However, there are treatment options available that can help patients see better outcomes and recover. But this requires timely intervention; here, visiting the best specialist is extremely important.
Tibial hemimelia is undoubtedly quite complicated, but variations and types result in many leg deformities and medical conditions in patients. Today, we are going to discuss Type 2 Tibial hemimelia.
Understanding type 2 Tibial hemimelia
The patients who suffer from type 2 Tibial hemimelia generally have distal and proximal tibial epiphysis articulating at the knee and ankle. The knee here is mobile but often unstable. This happens due to the absence of cruciate ligaments and the deficiency of certain parts of the tibial plateau.
Now, the ankle plafond is present; however, it is dysplastic, and thus, it will have problem in ankle joint movement. Here, the presence of a plafond differentiates it from Paley type 3 Tibial hemimelia, which is more deficient due to the lack of any tibial plafond.
In this case, ankle diastasis is not typical, but it can be present to some degree depending on the severity of the dysplastic changes in the tibial plafond. Also, the foot here is usually in Equinovarus.
Now that you know about type 2 Tibial hemimelia, let’s discuss its different classifications to better understand the case.
Type 2A
If the equinovarus deformity is greater than the malorientation of the tibial plafond, it can be due to a bony deformity. In such cases, the ankle should be distracted with an external fixator to correct the contracture, followed by realignment of the tibia with the foot.
Now, in case equinovarus does not exceed the tibial deformity, then in such situations, an osteotomy of the tibia for angular correction of the tibia with the foot is done. Also, it is combined with lengthening relative to the longer fibula. The circular external fixator extends from the femur to the tibia and foot.
Type 2B
In this type, the bracket epiphysis is present between proximal and distal tibial physis. It can be oriented in any direction and does not always correspond appropriately due to the deformity. The fibula here is a bit longer than the tibia. In such cases, treatment is to consider the direction of the bracket when planning the surgery. Here, to interrupt the bracket, the cartilage of the epiphysis and physis is cut, and an osteotomy is performed through the bone at the same level further to allow for more accurate correction of the deformity for which specific parts of the fibula must be resected.
The acute correction is accomplished by an opening wedge osteotomy on the side of the bracket, which can be done with or without a partial closing wedge on the opposite side.
Corrections can also be made with or without lengthening at the same time. With lengthening, an external fixator extends to the femur, while without lengthening, fixation is obtained with axial retrograde wires that enter through the foot and, if necessary, also cross the knee.
2C – Delayed ossification (cartilagenous anlage) of part, or all, of the tibia, dysplastic ankle joint, distal tibial physis absent, relative overgrowth of fibula.
Type 2C
In this type of Tibial hemimelia, you will find delayed ossification of the tibia. Now, when part of the tibia is affected, it will always be the distal part. An MRI examination is done to image the articulations between the tibia and femur and those between the tibia and talus. Based on this, a decision is made as to whether a deformity of the tibia must be corrected to reorient the anchor to the knee. Since the fibula is longer than the tibia, two options can be considered for managing the fibula.
- Resection to create a pseudarthrosis of the fibula
- Lengthening of the tibia done relative to the fibula
Also, it’s vital to understand that the ankle joint is present in this case, but it’s not functional. The goal is to create a plantigrade foot with a stable ankle. This usually requires destroying the ankle joint followed by secondary osteotomy, which best matches the articulation between the talus and tibia. Also, the syndesmosis may or may not need to be fixed with a syndesmotic suture washer device.
The unossified portion of the tibia over the years will ossify. However, the process can be accelerated using bone morphogenic protein, which can be inserted into the cartilage. This is an off-label use. Here, ossification of the tibia facilitates deformity correction and limb lengthening corrections of the tibia through bone. If sufficient parts of the tibia are bony, then an osteotomy can be done through the bony portion, and then pins are used in the bony portions. If an insufficient portion of the tibia is ossified to allow for external fixation, then open surgery is generally performed to realign the foot with a tibial osteotomy accurately. It is also combined with the sectioning part of the fibula diaphysis.
BMP2 is inserted into drill holes in the cartilage to ossify the tibial anlage. Further stabilization of the osteotomy is achieved using retrograde axial Kirschner wires through the foot and up the tibia. In most cases, ossification of the anlage is already seen by 3 months after BMP 2 implantation surgery. Meanwhile, lengthening is usually done one year after the ossification of the unossified tibia segment.
Conclusion
Tibial hemimelia is a complicated situation that requires proper medical attention. If you have someone who requires surgery, you should always rely on the best. Trishla Ortho has experts who understand the complexity of the surgery and can handle it with care. No matter the complications or difficulty, they can perform well and quickly relieve the patient.
