THE OCCURRENCE OF NEUROARTHROPATHY AFTER SURGERY FOR HEREDITARY SENSORY MOTOR NEUROPATHY(CHARCOT-MARIE-TOOTH DISEASE)
January 1st, 2003
Meir Nyska, MD* and Mark S. Myerson, MD
ABSTRACT
Although the clinical spectrum of hereditary sensory motor neuropathy (Charcot-Marie-Tooth disease) is quite varied, the peripheral neuropathy affects both motor and sensory nerves of the extremities. Many patients manifest a progressively worsening distal weakness, cavovarus, and forefoot deformity associated with a positive family history. In advanced cases, surgical correction with tendon transfer, osteotomy, and arthrodesis may be required to improve function and prevent progression of the deformity. We present the case histories of four patients who developed acute neuroarthropathy (three in the ankle, one in the midfoot) during the recovery period after reconstructive procedures to correct the deformity associated with Charcot-Marie-Tooth disease.
Key Words: Charcot-Marie-Tooth disease; Charcot joint; surgery
INTRODUCTION
Peroneal muscular atrophy is the most common form of inherited peripheral neuropathy, with an estimated incidence of 1 in 2,500 people. The disease was described by Charcot and Marie in France and by Tooth in England almost simultaneously in 1886.{2692} The hallmarks of diagnosis are a symmetrical wasting, weakness, and sometimes fasciculation of peripheral muscles, mainly in the legs. Sensory loss with severe or complete absence of pain perception occurs but is not always present nor demonstrable. Two thirds of the cases are familial. There are two main types of the Charcot-Marie-Tooth (CMT) disease, differentiated by time of onset: in type I, symptoms begin in adolescence; in type II, symptoms begin later, usually in the third or fourth decade. Most patients with Charcot-Marie-Tooth disease manifest foot and ankle problems that include weakness, painful forefoot callosity, difficulty with shoe wear, ankle instability, and problems associated with a high arched foot.{2688, 2685, 8440}
The occurrence of neuropathic arthropathy, or neuroarthropathy, is well recognized and associated with various forms of peripheral nerve dysfunction such as leprosy, diabetes, syringomyelia, spinal trauma, and tabes dorsalis.{2685} The association of neuroarthropathy and CMT disease has been recognized, but only rarely reported as affecting the spine, hips, ankles, or feet.{3034, 8437, 8438, 8441} Activation of a neuropathic arthropathy in the foot or ankle shortly after surgery in another region of the foot or ankle has not previously been reported. We describe four patients diagnosed with CMT disease in whom neuropathic arthropathy developed after reconstructive surgical procedures of the foot and ankle, resulting in rapid destruction of the involved joint(s).
PATIENT 1
A 60-year-old man with a history of type-I hereditary sensory motor neuropathy (CMT disease) had received treatment for 2 years for a nonhealing ulcer under the fifth metatarsal head of the left foot and, 2 years before presentation to our institution, had undergone resection of the distal fifth metatarsal for osteomyelitis. On presentation, his left foot had severe rigid cavoequinovarus and rigid clawtoe deformities, no function of the tibialis anterior or the peroneus brevis, only 2/5 strength of the extensor hallucis and extensor digitorum longus muscles, weak plantarflexion muscles (3/5), absent patellar and Achilles reflexes, and absent protective sensation (as determined by Semmes-Weinstein monofilament testing). Radiographs of the left foot and ankle demonstrated extreme cavus, varus deformity of the hindfoot and ankle, and an absent distal fifth metatarsal (Fig. 1, A, B, and C). The deformities of the right foot were similar, although not as severe, and although the pattern of muscle weakness was similar, the right hindfoot and ankle were more flexible.
The ulcer on the left foot was not associated with osteomyelitis and was initially successfully treated with a total contact cast.{2610} Because the deformities were not amenable to correction with a brace or shoe wear modifications, and recurrence of ulceration was likely, the patient underwent triple arthrodesis, lengthening of Achilles tendon, release of the plantar fascia, dorsiflexion osteotomy of the first metatarsal, and ankle ligament reconstruction. After surgery, there was improved alignment of the foot and solid fusion within 3 months (Fig. 1D). Six months later, the patient underwent hindfoot and forefoot osteotomies and tendon transfers on the right foot, which healed satisfactorily within 3 month. However, two months after this surgery, he developed swelling of the left (contralateral) ankle associated with warmth and experienced a sense of discomfort, although no pain. Initially, there were no associated radiographic changes. A work-up for infection included imaging studies and aspiration of the joint, which were negative. Two weeks after the onset of symptoms in the left ankle, radiographs demonstrated mild fragmentation and collapse of the talus and distal anterior tibia compatible with acute neuroarthropathy (Fig. 1, E. F, and G). This was treated for 2 months with restricted weightbearing and cast immobilization and then with a removable walking boot for 18 months until the neuroarthropathy had become stable. At the last follow-up examination, 3 years after the surgery on the left foot and ankle, the ankle joint was noted to be ankylosed with minimal deformity (Fig. 1H).
PATIENT 2
A 46-year-old man presented for treatment of recurrent right ankle instability, leg weakness, and painful swelling of the right ankle. This was associated with symmetric bilateral cavovarus deformity, which moderately limited his physical activity. He was noted to have marked ankle instability and weakness of the anterior tibialis (4/5) and peroneal muscles (3/5), although the peroneus brevis was not specifically examined. Semmes-Weinstein monofilament testing indicated decreased sensation, although protective sensation was present. Radiographs demonstrated mild degenerative arthritis of the ankle with instability of the talus on the stress views (Fig. 2A). Because this patient had not been previously diagnosed with CMT, electrophysiologic testing was performed, which confirmed the CMT diagnosis. After failed attempts at ankle bracing, he underwent a calcaneal osteotomy, Chrisman-Snook lateral ankle ligament reconstruction, tibialis posterior tendon transfer, and synovectomy of the ankle joint. Within 3 months, his recovery was good: he was ambulating with an ankle stirrup brace and had returned to full daily living activities. However, 6 months after the operation, he developed swelling of the ankle associated with pain. Radiographs demonstrated patchy avascular necrosis of the talus and fragmentation of the distal anterior tibia associated with severe osteolysis and fragmentation (Fig. 2, B and C). He was treated with cast immobilization and restricted weightbearing for 2 months, and then by a walking boot for 4 months until the swelling and inflammation had resolved. At 2.5 years after surgery, he had a stable ankle with no progression of neuroarthropathy (Fig. 2, D and E).
PATIENT 3
A 20-year-old woman experienced minor trauma to her right foot. Eight years later, she developed progressively worsening dysfunction associated with standing and walking. On examination, she had bilateral cavovarus deformity with mild tender swelling of the right foot predominantly located over the talonavicular joint. Passive midtarsal motion was painful. Weakness of the tibialis anterior muscle (4/5) and peroneal muscles (3/5) were noted. Radiographs demonstrated degenerative changes of the talonavicular joint consistent with posttraumatic arthritis. Based on electrophysiologic testing and a positive family history, a diagnosis of type I hereditary sensory motor neuropathy (CMT) was made. She underwent talonavicular fusion with a good initial recovery and no pain of the medial column of the foot. However, 3 months after surgery, she reported painful, warm swelling of the whole foot. The swelling and pain was attributed to a delayed union of the talonavicular joint, which was treated by cast immobilization for 2 additional months. The pain and swelling subsided gradually, and radiographs 1 month later demonstrated irregularity of the lateral midfoot with arthrodesis of the talonavicular joint. Computed tomography scans and subsequent radiographs demonstrated severe osteolysis with fragmentation of the lateral midfoot in the region of the calcaneocuboid joint, consistent with neuroarthropathy. This was treated with immobilization in a removable walker boot for 6 months. Eighteen months after surgery, the neuroarthropathy was no longer active, and no further destruction of the lateral midfoot joints was noted.
PATIENT 4
A 24-year-old woman with a severe cavovarus deformity associated with type-I CMT was treated by calcaneal osteotomy, posterior tibial tendon transfer, and osteotomy of the first metatarsal (Fig. 3A). Eight years later, she developed severe ulceration of the medial hindfoot associated with a nonbraceable planovalgus deformity. A triple arthrodesis was performed and followed by uneventful healing (Fig. 3B). One month after resumption of activities of daily living in a shoe with a stirrup brace (4 months after surgery), a severe, acute ankle neuroarthropathy developed with ankle subluxation associated with bone fragmentation (Fig. 3C). At surgery, considerable necrotic bone was found (negative culture), and the initial procedure was performed with antibiotic-impregnated bone cement (Fig. 3D). Arthrodesis was successfully performed 3 weeks later using a femoral head allograft and intramedullary fixation. Tibiotalocalcaneal fusion occurred at 4 months with no adverse sequelae 2 years later (Fig. 3, E, F, and G).
DISCUSSION
Neuroarthropathy is a well-recognized entity, predominantly involving weightbearing joints, characterized by osteolysis and fragmentation, with concurrent areas of bone destruction and healing secondary to an underlying neurologic disorder.
In the early stages of neuroarthropathy, cartilaginous fibrillation and narrowing with subchondral and endochondral bone formation occur in the affected joint. Later, the destructive changes are marked at the points of contact between the two articular surfaces, resulting in fragmentation of articular cartilage, destruction of ligaments, bone eburnation, and resorption. Massive osteophyte, loose bodies, and periosteal bone are formed. The joint capsule and synovium become thickened and edematous, initially with vascular spaces but later with fibrous tissue. Microscopic bone debris and cartilage in the capsule are considered by some to be pathognomonic of the process.{3503, 3496, 4387}
Neuroarthropathy associated with CMT, and affecting predominantly weightbearing joints, has been reported. Anand et al{8437} reported spinal neuroarthropathy that caused progressive painful scoliosis with vertebral destruction. A biopsy from the area of the destruction revealed fragments of sclerotic and reactive bone and fracture callus, suggesting a neuropathic process. Volken et al{8441} described three cases of rapid destructive hip osteoarthritis in CMT patients and Bruckner and Kendall{8438} reported five patients with CMT who developed neuroarthropathy in the foot and ankle. In all these cases, there was no definite cause that seemed to precipitate the neuroarthropathy. Medhat and Krantz{3034} reported two patients who developed neuroarthropathy, which, in one patient, developed 32 years after triple arthrodesis.
Limited sensation combined with activity is required to develop a neuropathic fracture. Neuroarthropathy is therefore seen only in those patients who are ambulatory and suffer from neuropathy, but not in those with neuropathy alone (for example, in patients with neuropathy resulting from spinal injuries). To develop neuroarthropathy, repetitive stresses to the foot must occur, similar to the pathogenesis of a stress fracture in the nonneuropathic foot. It is likely that, in the patient without neuropathy, stresses on the foot and ankle are easily accommodated with subtle and perhaps rapid adjustment of gait, posture, and activity. These subtle postural adjustments are not made by the patient with neuropathy, nor does he or she appreciate the extent of inflammation and potential injury after minimal daily but repetitive activities.
In a patient with neuropathy, an acute fracture requires a prolonged period of restricted activity and limited weightbearing, regardless of the type of treatment used (ie surgery or cast immobilization).{8605, 8606} Neuroarthropathy may develop during a period in which full bone healing has not yet taken place and when increased perfusion and vascularity are present in the affected region of the foot or ankle.{3503, 3496} It is likely that perfusion of the foot is in some way related to this disease process because neuroarthropathy seldom occurs in patients with extremely poor circulation. The local increase in blood flow may also be relevant, increasing the likelihood of localized bone resorption and, hence, the development of neuroarthropathy.
The initial elements of diabetic neuroarthropathy are osteolysis and fragmentation, changes which were documented for each patients and noted to differ clinically and radiographically from development or progression of preexisting ankle arthritis. In the current report, patient 2 had initial minimal arthritic changes of the ankle and patient 3 had obvious changes of the talonavicular joint (primarily narrowing and sclerosis). However, during the acute process, each patient developed severe osteolysis and fragmentation compatible with neuroarthropathy, not in patients with osteoarthritis.
For each of the four patients in the current report, the neuroarthropathy developed during the recovery period after surgery, shortly after a period of immobilization and once full activities were initiated. The neuroarthropathy developed in a region of the foot or ankle adjacent to the surgically stabilized site, indicating overloading of this region of the foot. These examples do not permit one to draw a conclusion about a particular type of surgery that may precipitate neuroarthropathy because various procedures (arthrodesis, osteotomy, ligament/tendon techniques) were performed. Fusion of one joint may overload adjacent joints; for example, one study{3032} found that patients with CMT who underwent a triple arthrodesis manifested a high incidence of ankle and midfoot arthritis in later follow-up. Similarly, a patient who has had a hindfoot fusion may develop a stress fracture, also as a result of the increased load on a part of the foot or ankle.{8608}
In conclusion, patients with CMT and neuropathy may be at risk for developing neuroarthropathy. After surgery, if painless swelling associated with warmth and erythema occurs, one must consider the possibility of acute neuroarthropathy. We have found that for these patients, the preferred method of treatment is prolonged immobilization in a cast followed by an appropriate brace or shoe until the extremity is stable. The patient with CMT and neuropathy must be carefully monitored, and one should recognize the potential risk for developing neuroarthropathy during treatment. Acute neuroarthropathy may occur after a sprain, a fracture, or even after a change in activities, similar to a stress fracture in the patient without neuropathy.{8605, 2702, 5328} For the four patients presented in the current report, the trigger for activation of neuroarthropathy was the surgery. The change in activity and local blood flow may have contributed to its development.
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