Foot and Ankle cases 8

A 48-year-old female presents to your office with worsening right ankle pain. Twenty years ago she sustained an ankle fracture, which was treated by open reduction and internal fixation. She subsequently underwent removal of hardware. She now is experiencing pain and swelling throughout the ankle, which is exacerbated by weight-bearing activities. Weight-bearing radiographs are obtained (Fig. 5–17A and B).

 

 

Figure 5–17 A, B: AP and lateral weight-bearing ankle radiographs.

 

What is the most common cause of ankle arthritis?

1. Inflammatory disease

2. Chronic ligamentous instability

3. Previous trauma

4. Primary degenerative disease (osteoarthritis)

 

Discussion

The correct answer is (C). Unlike the hip and knee, osteoarthritis of the ankle is relatively rare (<10%). Most patients who develop ankle arthritis have sustained previous trauma. Nonanatomic fracture healing alters joint contact forces and changes load bearing mechanics of the ankle, potentially leading to arthritis in the future. Inflammatory disease and instability are less common causes of ankle arthritis.

What forms of bracing and shoe wear modification may be helpful to control symptoms in this patient?

1. Lace up ankle support

2. Ankle foot orthosis (AFO)

3. Rocker bottom shoe

4. Patellar tendon weight-bearing orthosis

5. All of the above

 

Discussion

The correct answer is (E). Many patients with ankle arthritis will discover on their own that their symptoms can be mitigated using a high-top boot or shoe. A lace up ankle support is well tolerated and helps to minimize motion through the ankle. An AFO or Arizona brace (lace up leather brace) are more rigid bracing options that

often require the use of larger shoes. A patellar tendon weight-bearing orthosis offers the advantage of decreasing load across the ankle, although it is not typically well tolerated as a long-term solution. A rocker bottom shoe can be beneficial by transferring sagittal plane motion to the bottom of the shoe. A rocker bottom shoe can be combined with a cushioned heel to help absorb impact at heel strike.

Despite extensive nonoperative management, the patient has persistent pain and elects to proceed with ankle arthrodesis. Postoperative radiographs were obtained at 6 weeks (Fig. 5–18A and B).

 

 

 

Figure 5–18 A, B: AP and lateral ankle radiographs 6 weeks following ankle arthrodesis.

 

What is the recommended positioning of the ankle for arthrodesis?

1. Neutral plantar flexion, hindfoot valgus of 5 degrees, rotation equal to contralateral limb

2. 10 degrees of plantar flexion, neutral hindfoot varus/valgus, rotation equal to contralateral limb

3. 10 degrees of plantar flexion, hindfoot varus of 5 degrees, 10 degrees of external rotation

4. Neutral plantar flexion, hindfoot varus of 5 degrees, 10 degrees of external rotation

Discussion

The correct answer is (A), neutral plantar flexion, hindfoot valgus of 5 degrees, and rotation equal to contralateral limb (typically 5–10 degrees external rotation). Excessive hindfoot valgus will reduce the locking phenomenon of the transverse tarsal joints during the stance and push off phase of gait. This will in turn result in an excessively flexible midfoot and forefoot. Conversely, placing the hindfoot in

varus will lock the transverse tarsal joints and result in excessive midfoot and forefoot rigidity.

Following ankle arthrodesis, what is this patient most likely to experience?

1. Painful hardware

2. Ipsilateral hip and knee arthritis

3. Nonunion

4. Ipsilateral adjacent hindfoot arthritis

 

Discussion

The correct answer is (D). Adjacent hindfoot and midfoot arthritis eventually develops in most patients after an ankle arthrodesis. Adjacent joint arthritis is often seen on radiographs but may remain asymptomatic. Pain associated with the hardware may occur but is not a common complaint. Hip and knee arthritis have not been associated with ankle arthrodesis. Reported nonunion rates vary but on average are about 10%.

 

Objectives: Did you learn...?

 

Identify the most common cause of ankle arthritis?

 

 

Describe nonoperative bracing and orthotic options to treat ankle arthritis? Optimally position an ankle arthrodesis?