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Key Pearls On Using Distal Tibial Distraction Osteogenesis For Limb Length Discrepancy Due To Charcot
These authors present surgical pearls for performing distraction osteogenesis to correct leg length discrepancy due to Charcot neuroarthropathy in the hindfoot and ankle in two patients.
Charcot neuroarthopathy is a challenging condition that results in a loss of normal pedal architecture, gait dysfunction and soft tissue compromise, consequently leading to complex foot and ankle deformities.1 Due to the nature of the disease, osseous fragmentation and resorption occur, potentially resulting in profound limb length discrepancies (LLDs).
The goal of any surgical reconstruction for the Charcot foot/ankle is to create a stable, plantigrade foot that is braceable for prolonged community ambulation.1,2 To achieve this, one must also determine if a LLD exists. Traditionally, LLDs of less than 2 cm are considered insignificant.3–5 However, recent studies suggest that a LLD of 1 cm or more can significantly affect the biomechanics of the knees, hips and the lower back.3–5
There are conservative and surgical treatment options for LLD. The most common conservative treatment options consist of shoe modifications (i.e. lifts). This is recommended for patients who are not surgical candidates or those who have a plantigrade, braceable foot.3–5 Surgical interventions to restore height include the use of autografts, allografts, bone transport, custom titanium implants and distraction osteogenesis.6–9 Autograft is the recommended technique but harvesting increases both donor site morbidity and operation time.10–13 With the use of structural allografts, complications such as graft collapse, infection and nonunion can occur.14 Custom titanium implants can be difficult to acquire, are not readily available and studies have not established their long-term viability.7,15
Distraction osteogenesis is a surgical alternative that is suitable for various levels of LLD. The most common method to achieve length in distraction osteogenesis is by performing a proximal tibial osteotomy and lengthening.16 We present two cases of performing distraction osteogenesis to correct LLD due to hindfoot/ankle Charcot neuroarthopathy. With these cases, we apply key principles with proximal tibial lengthening distally at the supramalleolar level.
Case Study One: When A Patient With Ankle And Subtalar Joint Charcot Has Acute Hindfoot And Ankle Dislocation
A 53-year-old man presented to the emergency department with right foot/ankle pain and swelling, and was unable to ambulate. The pain started that day and he denied any traumatic event. His past medical history is significant for diabetes mellitus, HIV, chronic heart failure, peripheral neuropathy, obesity and chronic lymphedema.
During the clinical exam, the dorsalis pedis and posterior tibial artery were Dopplerable. A small 1x1 cm superficial ulceration was present at the medial malleolus due to the dislocation. The talus was palpable along the medial aspect of the midfoot but was not exposed. A radiographic review revealed the talus was medially dislocated and the fibula was fractured at the level of the ankle joint (see Figure 1A).
After medical stabilization and optimization, we took the patient to surgery the following morning. Intraoperatively, we noted the start of avascular necrosis in the talus (see Figure 1B) so we performed a right talectomy, resulting in significant bony loss and a LLD of approximately 2.5 cm. To address the LLD, we performed a supramalleolar osteotomy at the distal metaphyseal-diaphyseal junction to allow for gradual distal tibial distraction osteogenesis and simultaneously performed a tibiocalcaneal arthrodesis (see Figure 1C). The surgical goals were to create a stable hindfoot and ankle arthrodesis while regaining some of the lost length due to talectomy.
Over the next month, we performed incremental tibial lengthenings via strut adjustments. The patient gained 1.1 cm in limb length. At the time of external fixation removal, per the patient’s request, arthrodesis had occurred across the distal tibial fusion site. However, the bone regeneration had not consolidated completely. Therefore, the primary surgeon placed a medullary nail to stabilize the lengthened segment at the time of frame removal.
Almost one year after the initial surgery, the patient has been ambulating with a solid, plantigrade and stable construct for biomechanically favorable ambulation. His arthrodesis site and lengthening sites have healed (see Figures 1D/1E). The patient has since transitioned to a sneaker with a patellar-tendon brace.
Case Study Two: When A Patient With Alcoholic Neuropathy Has Ankle Joint Charcot And A Significant LLD
A 61-year-old woman presented with a Charcot deformity of the right ankle. Her past medical history was significant for lupus, Sjögren’s syndrome and alcoholic neuropathy.
The patient has a history of a failed right ankle fusion that ultimately resulted in a nonunion and varus deformity. As a result, the patient had severe osseous fragmentation and additional bony loss, resulting in a LLD of approximately 3 cm (see Figure 2A).
Revision right ankle surgery consisted of resection of the nonunion, application of a multiplanar external fixator and a supramalleolar osteotomy for distal tibia distraction osteogenesis and arthrodesis of the tibia to the calcaneus. Over the next two months, the patient had 1.5 cm of distal tibial lengthening. Arthrodesis of the ankle occurred around three months and consolidation of the bone regeneration occurred approximately six months after surgery (see Figures 2B/2C).
The patient has maintained excellent alignment for greater than one year and ambulates in a protective shoe with a patellar tendon brace.
In Conclusion
Charcot neuroarthropathy is a difficult condition to treat. When osseous destruction or avascular necrosis occurs, LLD and alterations in overall body biomechanics can result. Distal tibial distraction osteogenesis with simultaneous hindfoot and ankle arthrodesis is a powerful technique to correct LLD. This challenging method of correction requires expertise and technical skill in utilizing the Ilizarov method. Foot and ankle surgeons should consider this as an alternative for achieving length in this very complex patient population.
Dr. Michetti is a second-year resident with the Baltimore VA Medical Center and the Sinai Hospital of Baltimore.
Dr. Fink is a clinical fellow completing her Foot and Ankle Deformity Correction Fellowship at the Rubin Institute for Advanced Orthopedics/International Center for Limb Lenghthening in Baltimore.
Dr. Siddiqui is the Director of Podiatric Surgery and the Director of the Foot and Ankle Deformity Correction Fellowship at the Rubin Institute for Advanced Orthopedics in Baltimore.
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