Triple Arthrodesis Periprocedural Care

Updated: Oct 26, 2015
  • Author: Stephen M Schroeder, DPM, FACFAS; Chief Editor: Jason H Calhoun, MD, FACS  more...
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Periprocedural Care

Preprocedural Evaluation

Laboratory studies

If the underlying pathology is obvious and the pain is generated from degenerative joint disease (DJD), no specific laboratory tests are warranted except for standard preoperative studies. When the underlying diagnosis is not as clear, however, arthritis panels may be ordered to rule out inflammatory arthropathies or gout. If Charcot arthropathy is suspected, imaging studies or bone biopsy are the studies of choice. Joint-fluid analysis can also be performed if gout or an infectious process is suspected.

Imaging studies

Standard anteroposterior (AP), lateral, and oblique weightbearing radiographs are obtained as part of the initial workup. In severe cases, ankle, weightbearing AP, and mortise views should be included.

The three joints in question—that is, the talocalcaneal (TC) joint (also referred to as the subtalar joint [STJ]), the talonavicular (TN) joint, and the calcaneocuboid (CC) joint—are examined for degenerative changes manifested by joint-space narrowing, subchondral sclerosis, cyst formation, and osteophytic projection.

Osteophytes are easily identified at the TN and CC joints on the lateral and oblique views (see the image below).

Osteophytes and degenerative joint disease easily Osteophytes and degenerative joint disease easily seen at talonavicular, calcaneocuboid, and talocalcaneal (subtalar) joints.

The AP view reveals joint-space narrowing and abduction (common in valgus deformity) or adduction (common in varus deformity) of the forefoot (see the first image below). One can also appreciate the amount of uncovering of the articular surface on the talar head that is rotated medially from the concave articular surface of the navicular. More than 7° of displacement is considered abnormal and is commonly found in a valgus deformity with abduction of the forefoot (see the second image below).

Anteroposterior view depicting talonavicular and c Anteroposterior view depicting talonavicular and calcaneocuboid joints.
Articular surface on talar head rotated medially f Articular surface on talar head rotated medially from concave articular surface of navicular. More than 7° of displacement is considered abnormal and is commonly found in valgus deformity with abduction of forefoot.

The lateral view shows arch height. A low or collapsed arch indicates a valgus deformity, and a high arch indicates a varus or cavovarus deformity.

A useful adjunctive radiographic view is the Harris-Beath projection, which is taken with weightbearing, with the beam directed toward the posterior heel. Three views are shot, with the first angled 10° above the level of the declination angle of the posterior facet, the second angled at the same level, and the third angled 10° below. This allows the examiner to see the posterior facet joint space for pathology, as well as the amount of varus or valgus deformity in the rearfoot relative to the tibia (see the image below).

Harris-Beath projection allowing visualization of Harris-Beath projection allowing visualization of posterior facet of talocalcaneal (subtalar) joint and varus/valgus rotation.

Another adjunctive radiographic study is a standing full-length view of the legs. This is done to evaluate the mechanical axis of the tibia to the ground in patients with excessive genu varum. It becomes important because the foot must be fused in a position to accommodate these angles. [3] An example of this is a patient with 10° of tibia vara. The TC joint must be fused in at least 10° of valgus (rearfoot relative to tibia) in order to position the foot perpendicular to the ground. Fusing the foot in a varus position often leads to complications and should be avoided.

Magnetic resonance imaging (MRI) and computed tomography (CT) are rarely performed as part of a workup for triple arthrodesis. MRI can be useful, however, if avascular necrosis of the talus or navicular is suspected. It can also be helpful in identifying the extent of an infectious process or Charcot arthropathy.

Important normal joint angles to keep in mind when examining imaging study findings are as follows:

  • Lateral view (see the first image below) - TC angle of 25-50°; talus, first metatarsal angle of 0°; calcaneal inclination angle of 20-25°
  • AP view (see the second image below) - TC angle of 15-50°; talus, first metatarsal angle of 0°; degree of talar head rotation less than 7° from the navicular
Lateral view demonstrating talocalcaneal angle (ye Lateral view demonstrating talocalcaneal angle (yellow angle marker), talus first metatarsal angle (black angle marker), and calcaneal inclination angle (red angle marker).
Anteroposterior view demonstrating talocalcaneal a Anteroposterior view demonstrating talocalcaneal angle (black angle marker), talus first metatarsal angle (red angle marker), and degree of talar head rotation from navicular (yellow marker).

Other tests

Cavovarus deformities in the rear foot can result from a forefoot cavus deformity or an isolated plantarflexed first metatarsal. In these situations, the rearfoot compensates by rotating into varus. The Coleman block test is used to determine if the deformity is in the forefoot or hindfoot and to see if the deformity is reducible.

The forefoot is "off-weighted" by placing a block under the heel so that the rearfoot no longer has to compensate for a forefoot cavus. If the rearfoot normalizes and becomes perpendicular to the ground, the deformity lies in the forefoot and should be addressed as part of the procedure. In rigid cavovarus foot, the deformity does not reduce.

Diagnostic procedures

As mentioned above, if Charcot arthropathy is suspected, imaging modalities or bone biopsy are the studies of choice.

One of the most reliable office procedures for isolating joint pain from other pain generators is a local intra-articular anesthetic block. Relief of pain after injection confirms the location of the pain generator. Care must be taken to inject only into the joint, so that surrounding structures do not become anesthetized. TC joint injections are performed through the sinus tarsi. The sinus tarsi is palpated on the lateral aspect of the foot, and a 1.5-in. needle is directed toward a point just inferior to the sustentaculum tali on the medial side of the foot (see the images below).

Talocalcaneal (subtalar) joint injection via sinus Talocalcaneal (subtalar) joint injection via sinus tarsi.
Talocalcaneal (subtalar) joint injection via sinus Talocalcaneal (subtalar) joint injection via sinus tarsi.

The TN and CC joints may be more difficult to inject, especially when osteophytes are present, and may require fluoroscopic or ultrasonographic guidance may be required.

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Patient Preparation

The patient is placed supine on the operating table, and either general or spinal anesthesia is administered. A popliteal block should be considered to help with postoperative pain control. A proximal thigh tourniquet is applied, and a bump is placed under the ipsilateral hip. This positioning internally rotates the foot and allows easier access for the lateral incision and the ipsilateral iliac crest should autogenous bone graft be needed.

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Monitoring and Follow-up

The patient remains nonweightbearing (NWB) for 6-8 weeks and is then reevaluated. At that time, the patient is allowed to bear weight in a removable walker boot if no complications have arisen and trabeculation is noted on radiographs. Additional films are obtained at approximately 12 weeks and evaluated for consolidation. If stable fusion is observed, the patient is taken out of the cast boot and allowed to progress to normal shoes. The patient should undergo physical therapy for continued range-of-motion (ROM) and strength training.

Delayed union, especially at the TN joint, is not uncommon and may require further immobilization and NWB. [4]

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