Pertinent Pearls On Using Fibular Autograft With Ex Fix For Tibiocalcaneal Arthrodesis In Patients With Charcot Neuroarthropathy

These authors detail the treatment of three patients with Charcot neuroarthropathy in the hindfoot and ankle using a retrograde intramedullary nonvascularized fibular graft with supplemental external fixation.

Charcot neuroarthropathy is a progressive condition that may result in debilitating deformities and biomechanical instabilities affecting neuropathic lower extremities. It is a major cause of morbidity in patients with diabetes.¹ The altered lower extremity architecture can result in mechanical stress on the foot and ankle, and can result in cutaneous compromise.² Surgical intervention is indicated to address the malaligned, unstable non-plantigrade foot and ankle with or without ulceration(s) with bony prominences.³

The estimated rate of successful arthrodesis procedures with internal fixation in patients with Charcot neuroarthropathy ranges between 65 to 70 percent.^4,5 The risk of major amputation in patients with Charcot neuroarthropathy is approximately 15 to 20 percent.⁶ Intramedullary retrograde nail fixation of lower extremities affected by Charcot neuroarthropathy provides stable fixation and a reasonably high rate of fusion (84 percent), even in the face of poor bone quality.⁷ Despite the advantages, the use of intramedullary nail fixation has been associated with cortical hypertrophy, stress fractures of the tibia and plantar breakout due to poor cortical anchorage within the medial portion of the calcaneus.⁸ The inability to resist torque can cause failure of intramedullary nail fixation due to poor purchase of interlocking screws within osteoporotic bone.⁹

A Closer Look At The Potential Of Autogenous Bone And Fibular Grafts

Autogenous bone is the gold standard for bone graft material as it provides the necessary elements to generate and maintain bone, including osteoconductive scaffolding, osteoinductive growth factors and osteogenic progenitor cells.¹⁰

In 1906, Lexer and colleagues reported 21 cases of using fibula autograft as an intramedullary nail in a retrograde fashion for tibiotalocalcaneal arthrodesis in patients with Charcot neuroarthropathy.¹¹ In subsequent studies, researchers were able to achieve arthrodesis with supplemental external fixation, pins, screws or plates.^12-13 The fibula is the leading choice for autograft in the treatment of extensive bone defects of the upper extremities based on its favorable structural characteristics, reliable anatomy and low donor site morbidity.^14-16 Fibular grafts have demonstrated good results in augmenting fractures of elderly patients with poor bone stock and comminuted fractures.¹⁷

Jeong and coworkers first reported using intramedullary, non-vascularized fibular graft with external fixation for revisional ankle arthrodesis in a patient with Charcot neuroathropathy.¹⁸ After three months of postoperative stabilization with an external ring fixator, successful union was apparent radiographically. At 33 months postoperatively, the study authors found the patient had maintained a solid arthrodesis and had restoration of hindfoot alignment without complication.

A Guide To The Operative Technique

In a recent preliminary case series, we assessed tibiocalcaneal arthrodesis of the hindfoot with autogenous non-vascularized fibular strut in a retrograde, intramedullary fashion. We supplemented the fixation construct with circular external fixation.

The patient was supine on the operating table under general anesthesia. After ensuring the use of a popliteal block under ultrasound guidance and employing a well-padded thigh tourniquet, there was subsequent scrub, prep and drape of the lower extremity in the usual aseptic manner.¹⁹

For this procedure, one would direct attention to the lateral ankle and leg, and make a linear incision overlying the fibula (Figure 1). Perform layered dissection to the level of the lateral fibula. Transect the fibula using an oscillating saw in a manner to provide at least 16 mm of uniform diaphyseal bone. A lamina spreader can facilitate separation of the fibula from the soft tissue structures of the distal tibiofibular syndesmosis. Remove the transected portion of the fibula with care to protect the perforating peroneal artery (Figure 2A).

Then the surgeon passes the fibula off the field and removes the soft tissue along with the fibular head. Preserve the cortex of the fibula. Using an oscillating saw, fashion a notch along the entirety of the cortex of the fibular graft to prevent the formation of stress risers and reduce torque during insertion of the graft across the tibiocalcaneal arthrodesis. Approximately 12 mm of fibula will remain as the intramedullary fixation device. (Figure 2B). The surgeon would subsequently put the removed most distal portion of the fibula through a bone mill and utilize this as an autologous graft. (We did not do this in the third case study due to the infected distal fibula, which we supplemented instead with allograft bone chips.) Make an ancillary plantar incision for placement of a guide wire across the tibiocalcaneal arthrodesis surfaces following removal of the intervening cartilage. Then perform subchondral drilling with a solid drill bit prior to medullary reaming.

Hold the plantar foot 90 degrees to the leg with the tibial crest in line with the second ray and with a slight valgus attitude of the calcaneus. Utilizing a series of flexible reamers, ream the calcaneus and tibia in sequential order beginning with the 9 mm reamer and increasing in size to the diameter of the fibular graft, approximately 11 mm, and ream the calcaneus one to two diameters greater than the tibia to incorporate the bulkier portion of the fibula graft. Utilize the autologous bone collected during the reaming process to supplement the tibiocalcaneal arthrodesis site.

After completing the sequential reaming, pass the fibula graft over a guide wire into the pilot hole (Figure 3A and 3B). Utilizing a large mallet, gently insert the fibular graft in order to avoid fracture of the graft. Use multiple angles of intraoperative fluoroscopic visualization during the reaming process to ensure a sequential circumferential increase in diameter of the tibial isthmus. Verify the position and alignment of the fibular graft with multiple angles of fluoroscopic visualization to avoid formation stress risers or overt fracture.

After placing the graft, place two 4.0 cannulated screws across the tibia under fluoroscopic guidance in order to resist motion or translation of the fibula graft (Figure 4A and 4B). Confirm the clinical and radiographic position throughout all portions of the operation. Then flush the incision using copious amounts of normal sterile saline. Close the deep subcutaneous layer using 2-0 Vicryl followed by skin closure with 2-0 Prolene. Apply a circular external fixator (two tibial rings and a foot plate) with appropriate tensioning of all wires to provide additional stability.

How The Graft Worked In Three Patients

From January 2015 to August 2015, three patients with Charcot neuroarthropathy affecting the hindfoot and ankle received a retrograde intramedullary non-vascularized fibular graft with supplemental external fixation.

Case study 1. A 57-year-old Caucasian male had open reduction internal fixation (ORIF) of a bimalleolar fracture at another facility two years prior to his presentation. He had a medical history of insulin-dependent diabetes mellitus, peripheral neuropathy, coronary artery disease, myocardial infarction, pancreatitis and end-stage renal disease with hemodialysis three days per week.

As early as two months postoperatively, the loss of anatomic reduction was apparent on radiographs. By eight months postoperatively, a complete loss of reduction occurred, resulting in a malunion of the ankle fracture and loosening of the hardware (Figure 5A and 5B). In addition, there was resorption in the talus, resulting in a varus deformity of the hindfoot and ankle (Figure 6).

The patient presented with a full-thickness neurotrophic pressure ulcer to the lateral malleolus measuring 6.2 x 2.0 x 1.0 cm with a granular base. After the patient failed local wound care for two months, we removed the hardware and obtained bone biopsy and culture of the fibula following a modified 3-to-1 elliptical excision of the wound. The bone culture was positive for methicillin-resistant Staphylococcus epidermidis (MRSE). Pathologic evaluation revealed chronic osteomyelitis. We prescribed a six-week course of intravenous antibiotic treatment and the wound healed.

The patient began ambulating wound-free in a Charcot restraint orthotic walker (CROW). Due to the patient’s varus deformity, he subsequently developed an ulcer to the plantar aspect of the fifth metatarsal head (Figure 7). After multiple series of wound debridements, local wound care and progression of the varus deformity, we decided to proceed with using a retrograde intramedullary, non-vascularized fibular graft with supplemental external fixation to correct the varus malalignment that was contributing to the neurotrophic pressure ulcer formation.

Due to the collapse and resorption of the majority of the talus, we removed the remnant of the talar body during the operation. We performed a tibiocalcaneal arthrodesis (Figure 8A and 8B) and instructed the patient to remain non-weightbearing for three months postoperatively with crutch ambulation. We removed the external fixator at three months postoperatively and the patient utilized a short leg fracture walker for an additional three months.

At six months postoperatively, we allowed the patient to progressively bear weight with a CROW device and a four-pronged cane. We obtained serial radiographs every six weeks. Once fibrous union of the tibiocalcaneal joint formed a stable hindfoot with adequate graft position, the patient transitioned to full weightbearing with a CROW device with no assistance. The patient subsequently transitioned to wearing a low-profile brace for the operative ankle. Radiographs at eight months postoperatively demonstrated excellent consolidation without progression of the deformity and a well-maintained hindfoot alignment. Ultimately, the patient was fully weightbearing in a low-profile brace with no assistance (Figure 9).

Case study 2. A 50-year-old African-American male presented with a “rocker-bottom” foot deformity secondary to Charcot neuroarthropathy on his right side (Figure 10A & 10B). His past medical history consisted of hypertension, kidney transplant and insulin-dependent diabetes with peripheral neuropathy. The deformity developed over a one-year period with resorption of the talus. Although he was wound free, he had difficulty with ambulation in a custom orthosis due to his deformity. The patient had a retrograde intramedullary, non-vascularized fibular graft with supplemental external fixation to provide stability of his hindfoot and ankle to improve locomotion (Figure 11).

The patient was non-weightbearing immediately postoperatively for three months with crutch ambulation. At two weeks post-op, the patient developed an infected hematoma and wound dehiscence at the plantar heel. We performed incision and drainage with excisional debridement of the wound with primary closure. The intraoperative tissue culture revealed methicillin-resistant Staphylococcus aureus (MRSA). The patient received a prescription for minocycline (Minocin, The Medicines Company) for two weeks.

At three months post-op, we removed the external fixator and placed the patient in a fracture walker for an additional three months. Radiographs obtained at six-week intervals continued to demonstrate consolidation and fibrous union at the tibiocalcaneal fusion site. Subsequently, the patient developed an open wound to his anterior right ankle secondary to friction from the long leg boot.

We performed intraoperative excisional debridement with final cultures revealing MRSA. We prescribed the patient daptomycin (Cubicin, Merck) for six weeks via a Hickman catheter. The wound continued to increase in size and depth, exposing the anterior tibial tendon and resulting in necrosis. After tendon debridement, we placed a skin graft over the granular wound, which went on to heal.

At nine months postoperatively, the patient transitioned to ambulating in a CROW with no assistance. Radiographs at nine months postoperatively showed excellent consolidation with a well-maintained hindfoot alignment (Figure 12A & 12B). This alignment allowed the patient to be mobile with a plantigrade foot that remained wound-free. We subsequently lost the patient to follow-up.

Case study 3. A 81-year-old Caucasian male presented with varus malalignment of the right ankle as a result of Charcot arthropathy (Figure 13). He had a history of non-insulin dependent diabetes, peripheral vascular disease (PVD), peripheral neuropathy, myocardial infarction in 1985 and bladder cancer in remission. The deformity was present for two years. Bracing was unsuccessful and resulted in chronic wounds due to pressure and friction of osseous prominences.

The patient presented with a congested, erythematous right foot secondary to an infected wound overlying the styloid process of the fifth metatarsal (Figure 14). The patient had incision and drainage of an abscess with bone biopsy and culture of the fifth metatarsal, fourth and fifth metatarsal bases and distal cuboid (Figure 15A, 15B). Bone cultures revealed Acinetobacter baumannii, beta-hemolytic Strep, Streptococcus agalactiae, MRSE, methicillin-sensitive Staphylococcus aureus, Enterococcus faecalis, and Morganella morganii. Pathology evaluation demonstrated chronic osteomyelitis of the fifth metatarsal. The patient had a prescription for six weeks of intravenous antibiotic treatment. After two months of local wound care, we utilized a retrograde intramedullary non-vascularized fibular graft with supplemental external fixation due to the patient’s wishes to pursue limb preservation of his unbraceable ankle.

The patient was non-weightbearing postoperatively for the initial three months with crutch ambulation and local wound care for the lateral foot wound. Three wires of the external fixator failed at one month postoperatively and the patient returned to the operating room for pin replacement. We removed the external fixator at three months postoperatively and he utilized a fracture walker for an additional three months.

At six months, we allowed the patient to bear weight progressively on the left lower extremity with a CROW device and a four-pronged cane. We obtained serial radiographs every six weeks. Complete fibrous union of the tibiotalocalcaneal arthrodesis occurred with a stable graft position. The patient transitioned to full weightbearing with the use of an ankle brace with no assistance.

Radiographs obtained at 11 months post-op demonstrated consolidation without progression of the deformity and a well-maintained hindfoot alignment (Figure 16A, 16B, 16C).

The postoperative courses for the three aforementioned cases were nearly identical.

Final Words

It is well known that a successful ankle arthrodesis is hard to achieve in a patient with Charcot neuroarthropathy due to poor bone quality, immunocompromise and poor healing potential.⁴ The risk of major amputation approaches 15 to 20 percent after the use of internal fixation for tibiocalcaneal arthrodesis.⁶ The use of intramedullary nails has been associated with potential failure risks due to osteoporotic bone.⁹ Given the difficulty in management of deformities resulting from Charcot neuroarthropathy, it is important to choose procedures with low failure rates.

In this small case series, we attained a stable, plantigrade limb in lower extremities affected by Charcot neuroarthropathy by way of tibiocalcaneal arthrodesis performed with the use of an autogenous, non-vascularized fibular strut in a retrograde intramedullary fashion with supplemental circular external fixation.

It is important to consider possible complications associated with a fibula autograft. Researchers have documented major complications for intramedullary fibular autograft including fatal pulmonary embolism, fat embolus, cardiac arrest and a cerebrovascular accident.²⁰ Other complications include resorption or subsidence of the fibular graft that can result in loss of stability and consequently loss of limb.²¹

A non-vascularized fibula has less biologic potential than a vascularized fibula as it depends on the quality of the recipient site’s vascular and cellular environment.²² A vascularized fibula increases perfusion to a fracture site and promotes bone healing by supplying osteogenic cells.²³ Vascularized bone also provides higher biomechanical strength than non-vascularized bone.²⁴ Furthermore, a vascularized fibula provides perfusion for increased potential in healing.^25–28

Based on a literature review and a small case series, the use of a free fibular intramedullary strut graft should receive continued study as a viable option in patients with significant deformities or failed arthrodesis related to Charcot neuroarthropathy. Fibular autografts can minimize hardware complications when surgeons are trying to achieve a stable, plantigrade lower extremity in patients with poor bone quality.

Dr. Canales is the Chief of the Division of Podiatry and the Director of the Podiatric Surgical Residency Program at St. Vincent Charity Medical Center in Cleveland.

Dr. Patel is a third-year resident at the Podiatric Surgical Residency Program at St. Vincent Charity Medical Center in Cleveland.

Dr. Craig is a third-year resident at the Podiatric Surgical Residency Program at St. Vincent Charity Medical Center in Cleveland.

Dr. Reiner is an Advanced Foot and Ankle Fellow at the Northern Ohio Foot And Ankle (NOFA) Foundation in Concord, Ohio.

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