The Valgus Malaligned Triple With Subtalar and Transverse Tarsal Deformity

Indications

Residual lateral subfibular impingement, medial ankle, or medial arch pain
Radiographic valgus tilt of the talus in the ankle mortise
Secondary lateral knee pain, gait changes, or imbalance related to foot deformity
Symptoms interfering with normal daily activity

Indications Pitfalls

Skin breakdown or ulceration in the medial arch
Diabetic or nondiabetic peripheral neuropathy
Peripheral vascular disease
Other medical comorbidities precluding surgery

Indications Controversies

The most common cause of failure of a triple arthrodesis is undercorrection of deformity. The most common residual deformity is residual (subtalar/hindfoot) valgus with (transverse tarsal) supination.
Medializing calcaneal osteotomy and transverse tarsal derotational osteotomy may provide some deformity correction and is technically easier to perform. However, it does not have near the corrective power of arthrodesis takedown and revision fusion.
Concomitant arthritic change in the ankle: if mild to moderate and the ankle joint is salvageable, correction of the hindfoot deformity may ultimately preserve the ankle joint long term; if severe and the ankle joint is not salvageable, correction of the hindfoot deformity should still be performed but may need to be combined with ankle arthroplasty in a staged fashion. Extension of the arthrodesis to include the ankle (pantalar arthrodesis) may provide pain relief but would significantly limit function.

Examination/Imaging

Standing examination of the foot and ankle reveals an asymmetric severe flatfoot deformity.
The skin and soft tissue envelope are assessed for previous incisions, presence or absence of peripheral pulses, and overall condition.
Manual examination of the hindfoot demonstrates a fixed, rigid flatfoot, with tenderness to palpation in the lateral subfibular region and medial ankle, as well as bony prominence and tenderness in the medial arch area. In severe cases, there may also be tenderness along the lateral joint line of the ankle.
The foot is externally rotated relative to the lower leg. The tibial-foot axis (tibial tubercle to forefoot line) falls medial to the first ray, rather than aligning with the second ray ( Fig. 46.1 ).
The Achilles and the peroneus brevis were previously deforming forces when the deformity was flexible, and are now chronically contracted because of the fixed deformity.
The medial column should be assessed for hypermobility/instability.
Weight-bearing radiographs of the ankle and foot show residual implants in place. There is residual, excessive valgus through the subtalar arthrodesis, with residual midfoot abduction and residual plantar flexion sag through the talonavicular arthrodesis, with or without further sag in the medial column of the foot. There may also be valgus tilt of the talus in the ankle mortise, with or without associated arthritic change ( Fig. 46.2 ).
A computed tomography scan is invaluable in assessing arthrodesis healing and the extent to which the bony architecture of the hindfoot joints have been remodeled. The scan also provides additional information as to the extent of the deformity.

Surgical Anatomy

Bones and tendons of the hindfoot
Nerve supply to the hindfoot

Positioning

The patient is placed in the supine position, with a bump under the ipsilateral hip to internally rotate the leg, such that the anterior knee is perfectly perpendicular to the floor, which facilitates access to the medial and lateral aspects of the hindfoot.
A thigh tourniquet is essential to create a dry surgical field.
The procedure is typically performed under general anesthesia with a supplemental regional block (femoral–sciatic or popliteal) to optimize postoperative pain control.

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