51: Tibialis Posterior Tendon Transfer

Tibialis Posterior Tendon Transfer

Travis Matheney and Michael Glotzbecker

Indications

Spastic, flexible equinovarus-cavovarus foot deformity in the ambulatory child or adult with cerebral palsy or brain injury with “over-pull” of the tibialis posterior.

Recurrence of clubfoot deformity.

Patients with weak dorsiflexion secondary to neuromuscular disease.

Lengthening and transfer of the tendon have both been described.

Additionally, one may transfer all or half of the tendon.

Consideration should be given to whether the foot and ankle have adequate motor units to power dorsiflexion and are struggling with the varus over-pull of the tibialis posterior, in which case a split transfer might be advised; or the patient would benefit more from assistance with dorsiflexion and transfer of the entire tendon due to a general weakness of dorsiflexion.

Pitfalls

• Be certain to assess the gastrocnemius-soleus for contracture.

• Determine whether either isolated gastrocnemius or combined gastrocnemius-soleus lengthening is required.

• Consider gait analysis preoperatively to confirm activity of the tibialis anterior and posterior in the gait cycle.

Controversies

• Whether to transfer to the entire tendon or perform a split transfer is debated. Proponents of splitting the transfer state that the results are very good and do not risk collapse of the hindfoot into valgus, one complication of transferring the entire tendon.

Examination/Imaging

The peroneus brevis may be relatively weaker, allowing the tibialis posterior to “over-pull” the midfoot into supination and the hindfoot into varus, especially during the swing phase of gait.

The gastrocnemius-soleus must also be assessed for contracture.

The goal is a balanced foot in both stance and gait.

Hindfoot varus flexibility may be tested with the Coleman block test (Coleman and Chestnut, 1977).

Preoperative plain films, including standing anteroposterior, lateral, and oblique views of both feet, should be obtained to confirm no fixed bony deformity.

Treatment Options

• Prior to surgery, attempts can be made to improve range of motion with serial casting.

• An articulated ankle-foot orthosis or supramalleolar orthosis that can control the foot motion may be more desired by the patient and family.

Surgical Anatomy

The tibialis posterior has a broad insertion and is best found proximal to the first ray through the medial incision.

When transferring to the peroneus brevis, care should be taken not to completely disrupt the lateral fascia protecting the peroneal tendons from subluxation over the lateral malleolus.

Positioning

The patient is positioned supine with a small rolled blanket beneath the ipsilateral greater trochanter.

A nonsterile tourniquet is applied to the proximal thigh, and the remainder of the leg is prepped in sterile manner.

Portals/Exposures

Three incisions are outlined in Figure 1.

FIGURE 1

Three or four incisions are used, and incision placement depends on whether one is performing a whole-tendon or split-tendon transfer.

Pearls

• When transferring the entire tendon to the dorsum of the foot, it is possible to pull the released tendon from the medial incision through the anterior window in the interosseous membrane.

Procedure

Step 1

The tourniquet may be used at the surgeon’s discretion. The procedure does not typically result in a particularly bloody field.

If a gastrocnemius-soleus lengthening is required, this should be performed first and the wound closed before proceeding with the tendon transfer portion of the surgery.

Pearls

• Care should be taken not to overlengthen the gastrocnemius-soleus.

Step 2

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Tags: Operative Techniques Pediatric Orthopaedic Surgery

Jun 7, 2016 | Posted by admin in ORTHOPEDIC | Comments Off

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