Foot and Ankle cases 14

A 52-year-old female with a past medical history significant for long-term type 2 diabetes presents with a right foot ulcer. She is now 3 years post gastric bypass surgery which in effect cured her diabetes, however she has residual foot deformity and neuropathy with decreased sensation to the level of the mid tibia. She is afebrile, has a normal white blood cell count, and a mildly elevated erythrocyte sedimentation rate and C-reactive protein. On examination of her right foot she has an ulcer present over the plantar aspect of her first metatarsal head which extends to bone. There is no purulence or foul odor present. She has palpable dorsalis pedis and posterior tibial pulses, but her skin is dry and cracked in regions. Her last hemoglobin A1c was 5.9. An MRI was performed which demonstrates osteomyelitis of the metatarsal head. In addition to recommending an irrigation and debridement you recommend a Strayer procedure (lengthening of the gastrocnemius tendon).

Your indications for performing this are:

1. Isolated soleus contracture

2. Isolated Achilles contracture

3. Isolated gastrocnemius contracture

4. Negative Silfverskiold test

 

Discussion

The correct answer is (C). A lengthening of the Achilles tendon has been shown to decrease forefoot pressure and reduce the recurrence of forefoot ulcers. Because the gastrocnemius crosses the knee as well as the ankle, a positive Silfverskiold test (equinus contracture with knee extended which resolves when the knee is flexed) will be seen with an isolated gastrocnemius contracture. This contracture can be addressed by a lengthening of the gastrocnemius at the musculotendinous junction (Fig. 5–26). In a patient with an equinus contracture with the knee both flexed and extended, a formal Achilles lengthening procedure, such as a triple hemisection or z-lengthening, should be performed. An additional posterior capsulotomy may be required.

 

 

Figure 5–26 Clinical photograph of the musculotendinous junction of the gastrocnemius muscle.

 

Following debridement of the ulcer, Strayer procedure, and 6 weeks of culture specific antibiotics, the ulcer is healed on her right foot. At 12-week follow-up she reports a superficial ulcer on the contralateral foot at the plantar aspect of her second toe. Treatment options are discussed with her, and she is started with local wound care and diabetic shoes to unload this area. Prior to her next follow-up appointment, the following week she arrives in the emergency department with fevers, chills, an elevated white blood cell count and increased inflammatory markers. An MRI obtained by the emergency department demonstrates osteomyelitis of the distal phalanx of the second toe (Fig. 5–27).

 

 

 

Figure 5–27 Sagittal T2 MRI demonstrating edema in the distal phalanx of the second toe.

 

Debridement of the second toe at this point should also include potential:

1. Amputation

2. Evaluation of adequate vascular inflow to the foot

3. Heel cord lengthening

4. All of the above

 

Discussion

The correct answer is (D). Debridement of diffuse osteomyelitis at a distal phalanx often results in a complete or partial amputation of the toe. When a patient has osteomyelitis, it is important to assess the blood flow, potential pressure overload from a contracture, neuropathy, and a potential abscess. Reversible causes of an ulcer should be addressed such as debridement of the osteomyelitis, drainage of any abscess, and addressing any potential contractures. Addressing inadequate blood flow via a vascular intervention is recommended prior to any definitive amputations.

The patient heals a toe amputation uneventfully and asks what the likelihood of her having an additional amputation on her foot is. Your best reply is:

1. You are at very high risk of an amputation

2. It is very unlikely that you will require an amputation

3. There is not enough information present in the literature

 

Discussion

The correct answer is (A). In a patient who has had a previous diabetic ulcer, there is a very high risk for a recurrent ulcer (greater than 50% 5-year recurrence) and amputation (greater than 10% at 5 years). For patients with a prior amputation, the risk of ipsilateral repeat amputation is great than 20%.

 

Objectives: Did you learn...?

 

Discuss the value of addressing equinus contracture in a patient with forefoot ulcer?

 

Describe how to differentiate between an isolated gastrocnemius contracture and an Achilles contracture?

 

Pinpoint the importance of having adequate sensation in prevention of ulcer formation?