SUBTALAR MBA IMPLANT -- Pediatric
Your child has just been diagnosed as having flexible pediatric dysfunctional pes plano valgus deformity, otherwise known in layman's terms as pediatric flatfoot deformity. This abnormality means that when your child begins to ambulate and the foot touches the ground during the contact phase of gait, it is normally a mobile adapter causing the hindfoot to pronate or flatten. During midstance of gait, the subtalar joint of the rearfoot will begin to resupinate to form a rigid lever during the propulsive phase of gait. Flexible pediatric dysfunctional flatfoot deformity causes the subtalar joint of the rearfoot to pronate excessively during the contact phase. When this occurs, the foot is not allowed to resupinate during the late midstance phase, and the foot becomes hypermobile and does not allow for adequate propulsion. This imbalance of joint position and muscle function, if left untreated, will subsequently lead to acquired bunion deformities, neuroma formations, hammertoes, and early degenerative joint disease later in life.
The prime indication for performing any type of foot surgery on a patient that is diagnosed with a hyperpronation syndrome is the presence of pain. In the pediatric patient, this may include such parameters as walking intemperance, night cramps, athletic abstinence, sedentary hobby pursuits, arch pain, and postural pain in the feet and legs.
Fortunately, with children, flatfoot reconstructive surgery is much less involved than in the adult stage. Flatfoot reconstructive procedures performed in our practice encompass all of the following components:
- Bone grafting
- Insertion of wedges and/or fusion of the arch
- Achilles tendon lengthening
- Implantation of joint limiting devices, such as the MBA or STA-PEG
If flexible pediatric dysfunctional pes plano valgus deformity is diagnosed early in life, the treatment protocol can often be limited to a simple procedure entitled subtalar joint arthroereisis. This is an implant that is inserted into the sinus tarsi of the rearfoot and acts as a block to the excessive anterior and inferior displacement of the talus. This allows normal subtalar joint motion and blocks excessive pronation with resulting sequela. The state of the art implant that will be utilized in the procedure that your doctor is recommending is known as the subtalar MBA implant. This implant is relatively new and was designed by podiatrists, Dr. Jerry Maxwell from Oklahoma City, Oklahoma and Dr. Steven Brancheau from Texas. The MBA implant is a soft threaded device designed to be inserted between the posterior and middle facets of the subtalar joint. Unlike the traditional procedures, the MBA procedure does not require the resection of any cartilage or bone and is, therefore, relatively non-invasive. Additionally, the use of bone cement is not required, and the implant may be removed at skeletal maturity per the surgeon's discretion. It has been found that there is a very low incident rate of implant removal required, even at adolescent or adult stages of life.
The MBA's cannulated design allows for precise alignment and proper placement during surgery. The MBA is radiopaque and has a unique slotted design to absorb peak shock and impact stress while allowing fibrous ingrowth to buttress the subtalar joint. The cannulated nature of this implant, as well as the relatively non-invasive technique, allows this procedure to be easily reversed should any complications arise. You must understand that the MBA implant is not the panacea for flexible pediatric dysfunctional flatfoot deformities, and it is always important to fully evaluate the other coexisting deformities that need to be addressed when reconstruction is to occur. Occasionally, if the symptomatic flatfoot is reconstructed before the secondary adaptive changes occur, such as equinus or medial column faulting, arthroereisis may be the only procedure necessary for your child.
It is important to understand that the pediatric dysfunctional flatfoot deformity is a very complicated and surgically demanding entity. The primary reason for reconstructive surgery for the flatfoot condition is for improvement of pain. Not all patients will experience complete pain relief, but the vast majority will experience a significant improvement and enhancement of lifestyle. Occasionally, sequential surgeries may be required if the deformity cannot be corrected with the initial surgery. If your doctor elects to perform an MBA arthroereisis, your child will be in a weight-bearing cast at the time of surgery. Your child will be allowed to bear weight on both casts with the assistance of crutches for the first two weeks. During the following two weeks, your child will be allowed to fully bear weight without the crutches, unless other procedures were performed along with the MBA arthroereisis.
Those patients that require adjunctive bone grafting procedures often wonder where the bone graft is procured. We commonly use allogenic freeze dried cadaveric bone in the majority of our cases. Through the use of this cadaveric bone, we eliminate a separate surgery that would be needed to harvest the bone graft from your hip, which is typically an uncomfortable procedure. There have been no reported cases of transference of HIV or Hepatitis virus through the use of the freeze dried allogenic bone graft.
The surgeons of Beaumont Foot Specialists have been performing these types of procedures for over 20 years combined, and the outcomes are extremely gratifying and predictable in most cases. Please realize that the outcome of your surgery is only 50% contingent on the surgeon, and the other 50% on your compliance and adherence to your postoperative instructions. It is important for you to realize that you can expect improvement for at least 1-2 years after surgery.
Unless otherwise specified, the majority of patients undergoing flatfoot reconstructive surgery are required to be on crutches for two weeks. Your child can prepare for crutch ambulation by practicing prior to the surgery so that your child feels comfortable with them prior to the procedure. After the fiberglass cast is removed approximately 4-6 weeks after surgery, your child will be placed into a removable below-knee cam walker that resembles a cast. This cast can be removed for bathing and sleeping purposes only.
Once reconstruction has reached skeletal maturity and stability, your doctor will usually prescribe a custom-made orthotic to go into your child's shoe to help protect the surgical correction. This orthotic must be worn at all times and in all shoes for the first postoperative year. Once the implant is fully intact and has healed completely, your child may wish to occasionally go without the orthotic.
We, the physicians and staff of Beaumont Foot Specialists, pride ourselves in being the only Board Certified Foot and Ankle Surgical Group in our community who performs these very exacting and demanding procedures. These procedures have been performed not only on hundreds of patients, but also on many of our family members, staff and friends with extremely gratifying outcomes.
The physicians and staff of our office are available to serve you 24 hours a day, 7 days a week for all of your postoperative needs and concerns. Please feel free to contact us at anytime during your postoperative convalescence if you have any questions or problems.
» Back to Top