Hemiepiphysiodesis, also known as guided growth, is a widely used, minimally invasive surgical technique that gradually corrects angular limb deformity in X-linked hypophosphatemia (XLH) patients who are skeletally immature, i.e., children whose bones are still growing.
This procedure, in contrast to corrective osteotomy, is associated with less pain, lower costs, and fewer surgical risks.
What is XLH?
In patients with XLH, mutations in the PHEX gene result in the increased activity of a protein called FGF23, inhibiting the ability of kidneys to reabsorb phosphate. This leads to the excretion of phosphate in the urine, resulting in low phosphate levels in the blood that then cause bone deformities and weakness.
How does hemiepiphysiodesis work?
Hemiepiphysiodesis works by inhibiting one side of the physis (or growth plate of a bone) to halt bone growth on that side. This allows the other side of the bone to grow normally, enabling the correction of the angular deformity.
There are two types of hemiepiphysiodesis: temporary and permanent.
Temporary hemiepiphysiodesis is done by using staples or tension band plates that exert pressure on one side of the growth plate, and that can be removed once the deformity is corrected. Tension band plates are comprised of a two-hole plate with two screws on either side of the growth plate. This creates a non-rigid control outside the growth plate.
Temporary hemiepiphysiodesis is followed by physiotherapy and regular assessment of bone function.
Permanent hemiepiphysiodesis involves destroying one side of the growth plate by mechanical or thermal methods to allow bone growth through the remaining healthy growth plate.
This procedure is generally considered in cases when stapling or implanting tension band plates are difficult. It is effective but requires a perfect assessment of the timing of the surgery and precise calculation of remaining natural bone growth.
Limitations of hemiepiphysiodesis
Hemiepiphysiodesis is associated with a high risk of recurrence of the limb deformity. Thus, it is better to delay the surgery until closer to the end of skeletal growth. Poor timing can lead to a length mismatch, resulting in poor outcomes.
Temporary hemiepiphysiodesis can be complicated by migration or breakage of staples or plates, premature permanent physeal closure, and overcorrection. The use of staples also has numerous limitations such as staple failure, breakage, and extrusion from the bone.
Last updated: Jan. 20, 2019
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