The management of neuroarthropathic fracture and dislocation in the foot remains a challenge to the treating physician. Nonoperative management has remained the standard of care in these cases, and it usually proves to be adequate1-3. Surgery is reserved for patients with gross deformity or recalcitrant ulceration and may be limited to resection of osseous prominences and accommodative bracing, with satisfactory results4-8. There is a subset of patients who have grossly unstable dislocations in the midfoot that require more intensive treatment9-16. Disappointing results of nonoperative treatment have led some to advocate surgical intervention earlier in the disease process17.
Midfoot arthrodesis with osseous resection and osteotomy has been advocated for the treatment of neuroarthropathic midfoot deformity, but this disease process is inherently difficult to treat surgically. Loss of the initial surgical correction and high rates of nonunion are common sequelae when standard fixation techniques are used11-13,18,19. Poor bone quality, neuropathy, poor vascularity, and impaired nutrition of glycosylated tissues in patients with diabetes mellitus delay healing of the arthrodesis site and contribute to complications20. Patients with neuropathy also have difficulty with prescribed non-weight-bearing protocols and partial weight-bearing restrictions needed to achieve fusion21.
Evolving techniques have focused on increasing the stability of fixation primarily by extending fixation hardware proximally and distally into areas where the bone is not fragmented by the neuropathic process. These techniques include fixation with dorsal and/or plantar plates, fixation with crossed lag screws, fixation with axial screws from the talus and calcaneus, and external fixation, although clinical evidence supporting some of these techniques is lacking14,15,22-24.
The purpose of this study was to evaluate a technique of midfoot arthrodesis with use of multiple axial screws placed in the metatarsal shafts for fixation in patients with unstable midfoot neuroarthropathic deformity. The goal of treatment was to establish a plantigrade foot that was resistant to ulceration and allowed functional walking with the use of standard diabetic shoe wear. Our hypothesis in developing this technique was that spanning the area of dissolution and achieving fixation in normal-quality bone proximally and distally would afford adequate fixation to achieve fusion and maintain deformity correction despite the challenges associated with neuropathy and diabetes. The advantage of placing the screws in the medullary canals of the metatarsals is the avoidance of both excessive periosteal stripping and the creation of stress-risers caused by drilling holes in cortical bone. Alignment is also simplified by the use of cannulated screws as the foot can be held reduced and pinned axially with the screw guidewire prior to application of the final hardware. Compression across the fusion site is accomplished by tightening the screws. We report our experience with this procedure in twenty-two patients who had severe deformity due to Charcot neuroarthropathic disease of the midfoot.
We conducted a retrospective study of twenty-two patients (twenty-two feet) with Charcot midfoot neuroarthropathy who had undergone surgical reconstruction for the treatment of midfoot collapse between 1989 and 2004. All patients were referred by an outside physician or surgeon to the private practice of the two senior authors (V.J.S. and G.J.S.), which is a tertiary referral center for foot and ankle reconstructive surgery. The average age of the patients was 59.4 years (range, forty-five to eighty-one years), and the average duration of follow-up was fifty-two months (range, twenty-four to 137 months). There were sixteen women and six men. Nineteen patients had diabetic neuropathy, and three had idiopathic neuropathy. Of the nineteen patients with diabetes, fourteen were insulin-dependent. All patients presented with a unilateral unstable rocker-bottom deformity of the foot that had been present for at least three months. Four patients died since the start of the study.
A history was recorded; a physical examination was performed; and standard radiographs, including anteroposterior and lateral weight-bearing views and an oblique view of the foot, were made. The pattern of osseous deformity was classified with use of the Charcot midfoot classification described by Sammarco and Conti19. In this system, Pattern 1 indicates diastasis between the first and second metatarsals with fragmentation and collapse extending across the tarsometatarsal joints; Pattern 2, medial metatarsocuneiform destruction without diastasis between the first and second metatarsals; Pattern 3, arthropathy at the navicular-medial cuneiform joint with fragmentation of the middle cuneiform and destruction across the lateral tarsometatarsal joints; Pattern 4, arthropathy of the first metatarsal-medial cuneiform joint with diastasis between the first and second metatarsals and proximal and lateral extension into the intercuneiform joints ending at the calcaneocuboid joint; and Pattern 5, perinavicular arthropathy with distal intertarsal fragmentation and extension (Fig. 1). Nine patients had Pattern 1, six had Pattern 3, and seven had Pattern 5. The deformities were also classified radiographically according to the system described by Schon et al.25. Nine patients had Type-1 deformities, six had Type-2, and seven had Type-3. The deformities were also designated as Schon Type alpha or beta, which indicates the severity of the deformity. A beta stage indicates more severe deformity and is assigned if one or more of the following criteria are met: (1) a dislocation is present, (2) the lateral talar-first metatarsal angle is =30°, (3) the lateral calcaneal-fifth metatarsal angle is =0°, or (4) the anteroposterior talar-first metatarsal angle is =35°. One patient had a Schon Type-alpha deformity, and twenty-one patients had a Schon Type-beta deformity. Of the Schon Type-beta deformities, nineteen were given this designation because of a dislocation of the midfoot and two, because of an angular deformity.
At the time of presentation, all patients had Eichenholz Stage-I disease, which is typified by a grossly swollen, erythematous foot with midfoot instability present on physical examination26. Thirteen patients presented without ulceration, and nine patients presented with plantar skin ulceration. According to the method of Wagner, six of these ulcerations were classified as Grade 1; one, as Grade 2; and two, as Grade 327. All patients without ulceration were treated initially with immobilization in a total contact cast or a diabetic boot walker (Aircast XP Diabetic Walker; DJO, Vista, California). Patients were instructed to limit both walking distance and weight-bearing to 50% and were given crutches or a walker. Patients with palpable pulses were treated with a cast initially. Patients with Wagner Grade-1 or 2 ulceration were treated with weekly local débridement in the physician's office, followed by immobilization with a total contact cast or a boot walker. The decision to use a cast or boot walker initially was based on the need for access to the limb for vascular testing, or for diagnostic nuclear imaging if that was needed to rule out osteomyelitis. Once testing was completed, a total contact cast was used until the ulcer resolved. Two patients with Grade-3 midfoot ulceration presented initially with methicillin-resistant Staphylococcus aureus osteomyelitis and underwent staged reconstruction. These patients underwent soft-tissue débridement, resection of infected bone, and temporary implantation of tobramycin-impregnated methylmethacrylate beads followed by six weeks of intravenous vancomycin. All ulcers had healed by the time of the arthrodesis. In the two patients who had had osteomyelitis, bone specimens were obtained at the time of the arthrodesis and were negative on culture.
The primary indication for surgery was an unstable midfoot deformity that was not responsive to nonoperative treatment. Instability was defined as a midfoot fracture-dislocation associated with dorsal dislocation and proximal migration of the metatarsals—i.e., a bayonet deformity25. Feet that showed progressive dislocation, an increase in deformity, or recurrence of ulceration following discontinuation of treatment with a contact cast were also considered to be unstable and unbraceable. These feet typically had a sharp prominence of the navicular, medial cuneiform, or cuboid on the plantar aspect of the foot. Nonoperative care was considered to have failed for all patients in the series.
Preoperatively, all medical comorbidities were assessed and controlled by the patient's primary care physician or an internal medicine specialist. Comorbidities included hypertension (ten patients), hypothyroidism (seven), coronary artery disease (three), a prior pancreas or kidney transplant (two), atrial fibrillation (one), osteoporosis (one), asthma (one), congestive heart failure (two), gout (one), pulmonary hypertension (one), chronic pain (one), hypopituitarism (one), a history of colon cancer (one), and a history of stroke with hemiplegia of the contralateral extremity (one). All patients underwent noninvasive vascular testing, including digital arterial Doppler studies to ensure that the blood supply to the forefoot was adequate for wound-healing. Patients with an ankle-brachial index of <0.7 and those with absent digital waveforms on Doppler arterial examination were not considered candidates for surgery unless they were cleared by a vascular surgeon.
Operative Technique
The procedures were performed with use of general anesthesia. The patient was positioned supine, and a pneumatic thigh tourniquet was applied. Prophylactic intravenous antibiotics (1 g of cefazolin, or 600 mg of clindamycin for patients allergic to penicillin) were administered preoperatively. All patients had a substantial contracture of the Achilles tendon complex, and this was addressed surgically at the beginning of the procedure in order to achieve 20° of passive ankle dorsiflexion. A gastrocnemius-soleus muscle recession was performed in fourteen of the twenty-two patients, and a percutaneous Achilles tendon lengthening was done in four patients. Four additional patients underwent a gastrocnemius-soleus muscle recession and then a percutaneous Achilles tendon lengthening when the muscle release alone did not result in adequate ankle dorsiflexion.
The reconstruction was done in four stages: (1) exposure, (2) resection of bone and preparation of the arthrodesis bed, (3) reduction of the deformity, and (4) application of the fixation hardware (Figs. 2-A through 2-F). Surgical exposure consisted of a medial incision at the apex of the deformity and one or two dorsal longitudinal incisions placed centrally and laterally as needed to gain access to the middle and lateral columns. The medial incision extended along the medial border of the foot, and all efforts were made to preserve a full-thickness myocutaneous sleeve. The abductor hallucis muscle was retracted inferiorly. If the tibialis anterior tendon had to be detached for exposure, it was secured with a nonabsorbable suture for repair during closure. Care was taken not to detach the posterior tibial tendon, but if extensive fragmentation was present and the tendon was avulsed, it was secured with a suture and repaired to bone at closure. An extraperiosteal exposure of the medial column was done, and the apex of the deformity was exposed superiorly and inferiorly. The middle column was exposed through a dorsal incision centered between the second and third metatarsal bases. If the fourth and fifth tarsometatarsal joints were involved, a third longitudinal incision was made in line with their bases and extending over the cuboid.
Resection of bone and preparation of the arthrodesis bed were done simultaneously. In most cases, the soft-tissue envelope was contracted as a result of the chronic dislocation and adequate bone had to be resected to achieve realignment without excessive soft-tissue tension, which can compromise the vascular structures. Fragmentation of bone in the medial column of the foot was commonly encountered, and resection of bone in the middle and lateral columns was sometimes necessary to prevent gapping at the arthrodesis bed medially. Preparation was first done medially. A microsagittal saw was used to resect the involved articular surfaces and to remove plantar bone as necessary. Bone was excised sparingly, with removal of just enough to obtain a tension-free reduction. Often, the area of fragmentation was filled with dense scar tissue, which was excised along with free fragments of apparently avascular bone. The normal joints were not prepared for fusion to preserve the strength of the subchondral bone and the osseous circulation of those structures.
Preparation for the arthrodesis and the correction of the deformity proceeded from medial to lateral. With use of a microsagittal saw, bone and cartilage at the involved joints were excised from dorsal to plantar as necessary to achieve a balanced reduction of the medial column. If the lateral column was involved, the fourth and fifth tarsometatarsal joints were prepared by resecting the articular surfaces with a sharp chisel or saw.
Reduction of deformity was facilitated by using guidewires from the cannulated screw set. The goal was to pass the guidewires into the medullary canals of the metatarsals without breaching the diaphyseal cortex of the bone. A 3.5-mm guidewire was typically used for the medial column, and 2.0-mm guidewires were typically used for the lesser metatarsals. In the earlier cases, the guidewire for the medial column was passed percutaneously through the posterior aspect of the ankle capsule into the body of the talus. The wire was then passed through the talar neck and head and guided fluoroscopically through the medial column and into the first metatarsal. This technique has since been abandoned as it is technically difficult and multiple wire passes were often necessary to achieve adequate positioning of the hardware and the arthrodesis. In more recent cases, the wire has been inserted into the medullary canal of the first metatarsal in a retrograde fashion through the metatarsophalangeal joint by maximally dorsiflexing the joint and then passing the wire under fluoroscopic control into the shaft of the metatarsal. Alternately, when the dislocation was at the level of the tarsometatarsal joint, the wire was passed into the shaft of the metatarsal through the resected portion of the metatarsal base and then out through the metatarsophalangeal joint distally. Guidewires were passed under fluoroscopic control into the second, third, and fourth metatarsal shafts by dorsiflexing the respective metatarsophalangeal joint and passing the wires percutaneously, plantarly through the metatarsal head. When the base of the metatarsal has been exposed and excised as part of the arthrodesis, the wire can be passed antegrade into the shaft and out the metatarsal head and skin distally. Once the wires were placed, they were advanced to the level of the deformity, the deformity was reduced, and the wires were advanced across the fusion site. Fluoroscopy was used at this point to judge whether the reduction was acceptable.
For final application of the hardware, the path for the screws was prepared by reaming the medullary canals and screw paths with cannulated drill bits and then manually tapping the screw path. This step cannot be skipped as, without it, the metatarsal may fracture. The medial column was drilled with a 5.5-mm cannulated drill bit and pretapped for the appropriate 6.5 or 8.0-mm screw (DePuy Orthopaedics, Warsaw, Indiana). The screw hole in the talar body (if an antegrade screw is used) or in the metatarsal head must be countersunk so that the screw head can be inserted deep to the subchondral bone without fragmenting the bone. The medial column screw was placed first. The lesser metatarsals were sequentially reamed with drill bits of increasing diameter until a diameter of 3.5 or 4.5 mm was reached. The screw path in the metatarsal was then tapped with a 4.5 or 5.0-mm tap, and the screws were passed under fluoroscopic control. Reduced-head screws of 4.5 or 5.5 mm in diameter (DePuy Orthopaedics) were used preferentially, as the head diameter facilitated intramedullary placement. The screw was advanced until the head passed to the metaphyseal-diaphyseal junction, where it became engaged. The screws were tightened beyond this point to compress the arthrodesis site.
Nine feet required arthrodesis of the talonavicular joint as part of the reconstruction. Of those undergoing talonavicular arthrodesis, two also required fusion of the subtalar joint and one, of the calcaneocuboid joint. The decision to fuse the talonavicular joint was based on the degree of comminution of the navicular or the ability to achieve adequate fixation proximally in the foot. All feet with Sammarco-Pattern-5 involvement had severe comminution of the navicular, which necessitated arthrodesis of the talonavicular joint. One patient with a Sammarco-Pattern-3 dislocation underwent arthrodesis of the talonavicular joint as poor bone quality and navicular comminution did not allow adequate fixation proximally. One foot with a Pattern-1 dislocation had severe comminution of the cuboid, and bone stock in the medial column was inadequate for fixation without crossing the transverse tarsal joint. In this patient, the calcaneocuboid and talonavicular joints were fused as part of the surgery. Two feet with Pattern-5 deformity presented with lateral subluxation of the subtalar joint and a severe valgus hindfoot deformity. These feet underwent simultaneous correction of the hindfoot alignment with subtalar arthrodesis. Fusion of additional joints was accomplished by denuding the articular cartilage and fragmenting the subchondral bone plate with a sharp chisel. The talonavicular and calcaneocuboid joints were approached by extending the medial and lateral incisions, respectively. The subtalar joint was approached through a separate dorsolateral Ollier-type incision through the tarsal sinus. Fixation of the talonavicular and calcaneocuboid joints was achieved by passing the axial intramedullary screws across these joints. The site of the subtalar arthrodesis was fixed with a single 6.5-mm screw passed from the calcaneus into the talar body.
Postoperative Care
A posterior splint with thick cotton padding was applied in the immediate postoperative period. Patients remained in the hospital for one to three days postoperatively for control of medical comorbidities and for gait training. Non-weight-bearing was prescribed and a physical therapist provided instruction during the hospitalization until the patient demonstrated the ability to walk for short distances with a walker or crutches and to transfer effectively. However, compliance with weight-bearing restrictions was noted to be poor even during the hospitalization. The postoperative dressing was changed after two or three days, and a short leg cast was applied. The cast was changed weekly, and then monthly as the soft-tissue envelope improved and swelling decreased. Sutures were removed after twenty-one to twenty-eight days. The average period of cast treatment was 16.3 weeks (range, seven to twenty-eight weeks) from the day of the surgery. As osseous union was seen to progress radiographically, partial weight-bearing with use of a removable pneumatic walking boot was permitted. The average period of prescribed non-weight-bearing was 5.8 months (range, 3.5 to 9.5 months). Patients were then instructed to limit weight-bearing to 50% for three weeks, after which repeat radiographs were made. If the radiographs did not show any motion at the arthrodesis site, loss of correction, or loosening of hardware, full weight-bearing in the pneumatic walking boot was allowed. When the postoperative edema had subsided and the radiographs demonstrated stability at the fusion site, a multidensity foam orthotic device was prescribed and the patient was counseled to obtain accommodative footwear. The average period of boot or brace wear was 11.7 weeks (range, three to twenty-eight weeks) following cast treatment.
Radiographic Analysis
Measurements made on anteroposterior and lateral weight-bearing radiographs of the foot, obtained during the initial visit, the immediate postoperative visit, and the final clinical visit, were analyzed. At the immediate postoperative visit, radiographs were made with the patient sitting and the foot pressed firmly on the x-ray plate to simulate weight-bearing and facilitate comparison with the weight-bearing radiographs. Standardized measurements were performed with use of the methods described by Schon et al.25, Gould28, and Sangeorzan et al.29. The talar-first metatarsal angle was measured on the anteroposterior radiograph, and the talar-first metatarsal angle, the talar declination angle, the calcaneal-fifth metatarsal angle, and dorsal displacement at the apex of the deformity were measured on the lateral radiograph. Dorsal displacement was measured on the lateral radiograph as the vertical distance between the axis of the talus and the axis of the first metatarsal at the level of the midfoot dislocation (Fig. 3).
Paired t test analysis was performed to compare preoperative radiographic measurements with immediate and final postoperative measurements. Paired t test analysis was also done to compare immediate postoperative radiographic measurements with final measurements. Results were corrected for multiple comparisons with use of the Bonferroni method. Findings were considered to be significant if the p value was <0.05.
Source of Funding
There was no external funding for this study.
The clinical data and complications are summarized in Table I. There was radiographic evidence of complete union in sixteen of the twenty-two patients. Five patients had a nonunion of a single joint in an otherwise stable foot (partial union). One patient (Case 9) showed no radiographic signs of healing and subsequently had failure of hardware and collapse of the longitudinal arch. An ulcer also developed beneath the medial sesamoid in this patient, prior to the hardware failure, as described in detail in the Complications section. All patients had returned to a functional ambulatory status at the time of final follow-up. Nineteen patients returned to wearing standard over-the-counter shoes with multidensity foam orthotics, whereas three required custom extra-depth shoes.
Radiographic data are summarized in Table II. A comparison of the means of all measured radiographic parameters indicated a significant correction, as compared with the preoperative values, at both the immediate and the final radiographic evaluation (p < 0.05 for all values). The immediate postoperative and final postoperative radiographs were compared to determine whether correction had been maintained over time, and these data are summarized in Table III. Comparison of the means showed no significant loss of correction of the anteroposterior talar-first metatarsal angle, the lateral calcaneal-fifth metatarsal angle, or the amount of dorsal displacement (p > 0.05). There was a significant loss of correction of the lateral talar-first metatarsal angle and the talar declination angle (p < 0.05), although the final measurements remained significantly improved as compared with the preoperative values.
Complications
Six patients had a screw removed because of prominence of the screw head. Four of these screws were at the fifth metatarsal base and had been inserted obliquely (i.e., they were not intramedullary screws). One that had been placed from the calcaneus into the fourth metatarsal shaft, crossing the calcaneocuboid joint, backed out posteriorly. These five screws were removed in the physician's office without anesthesia. One screw in the first metatarsal that crossed an uninvolved talonavicular joint backed out into the metatarsophalangeal joint, causing a cock-up deformity of the hallux and a plantar ulcer under the screw head. This screw was removed in the operating room, and the ulcer was left open. Both the hallux deformity and the ulcer resolved without further intervention.
Seven patients had a broken intramedullary screw(s), which was removed from two patients. The intramedullary screws were removed with use of the Easy Out device (DePuy Orthopaedics), which was threaded into the shaft of the cannulated screw under fluoroscopic control. One patient in whom the medial column had been fixed with an 8.0-mm screw extending from the first metatarsal into the talar neck was noted to have a bent screw on radiographs made at six months. Autogenous bone graft from the proximal part of the tibia was applied to the arthrodesis site. The bent medial column screw was exchanged percutaneously with another 8.0-mm screw placed through the metatarsophalangeal joint by cannulating the bent screw with a guidewire under fluoroscopy, backing that screw out with a screwdriver, and placing a new screw over the guidewire across the arthrodesis site.
No complications or symptoms resulting from soft-tissue injury due to the passing of hardware through the metatarsophalangeal joints or through the posterior part of the ankle capsule were noted. Osteonecrosis of the talus developed fourteen months following subtalar, talonavicular, and midfoot arthrodeses in one patient. A salvage pantalar arthrodesis was performed. Severe cellulitis and a soft-tissue infection developed six months following the index procedure in a patient who had had preoperative methicillin-resistant Staphylococcus aureus osteomyelitis. It was treated with an eight-week course of intravenous vancomycin and resolved without the need for additional surgery or hardware removal.
A perioperative fracture occurred in three patients. One patient fell two weeks after the surgery and sustained a fracture of the navicular, where the threads of an 8.0-mm screw had been placed. The fracture was treated with reduction and percutaneous fixation with a 4.0-mm cannulated screw. In another patient, a fracture of the first metatarsal head occurred, and was recognized, intraoperatively as an 8.0-mm screw head was countersunk. It was reduced and was fixed with two 3.0-mm cannulated screws. One patient sustained a stress fracture of the calcaneus six months following the surgery; it healed with protected weight-bearing in a pneumatic walking boot.
Plantar ulceration developed postoperatively in four patients. In one of them, a Wagner Grade-2 ulceration, which was thought to be primarily related to inappropriate shoe wear, developed under the second metatarsal head seventeen months after the surgery. It resolved after treatment with a total contact cast for two weeks and long-term use of a custom orthotic device. The ulcers in the other three patients involved the first ray. One Grade-2 ulcer at the first metatarsophalangeal joint developed thirteen months after successful fusion and appeared to be related to a plantar flexion deformity of the first ray. It required removal of the medial column screw and a dorsiflexion osteotomy of the first ray. A good long-term result was achieved. One ulcer was due to a prominent screw in the first metatarsophalangeal joint, and it resolved after screw removal. A Grade-2 ulcer developed in another patient (Case 9); excision of the medial sesamoid was performed eight months postoperatively, and the ulcer resolved. This patient weighed 300 lb (136 kg) and could not comply with weight-bearing restrictions during the postoperative period. While good correction of the initial dorsal displacement, which had measured 38 mm, and of a severe bayonet deformity was achieved, at the time of final follow-up (at forty-eight months), the patient had a collapsed arch, an abducted foot, and a nonunion of the medial column arthrodesis. However, there was no recurrence of the bayonet deformity and no dorsal displacement at the time of final follow-up. At this time, the patient was walking with an off-the-shelf diabetic shoe and an accommodative orthotic device.
The treatment of neuroarthropathic fractures in the foot and ankle presents substantial challenges that are not easily overcome. While most patients can be managed effectively with standard conservative measures, there are those who continue to have ulceration and progressive deformity despite conservative management. A recent review of the nonoperative treatment of Charcot arthropathy at a large tertiary center demonstrated a 2.7% annual rate of amputation, a 23% rate of brace wear for more than eighteen months, and a 49% rate of recurrent ulceration; these findings led the authors to suggest that better techniques for treatment are needed30. In the present study, we described one approach to management of this difficult-to-treat subset of patients with midfoot dislocation for whom more standard conservative care had failed.
Radiographic and clinical classifications of neuropathic midfoot deformity have been developed in part to help predict which fracture patterns will be amenable to conservative management and which will do poorly19,25,31. The feet in this study were classified according to the patterns described by Sammarco and Conti19 and by Schon et al.25. Sammarco Pattern-2 disease, which is limited to the first tarsometatarsal joint, was not treated with the technique described in this study, as this pattern is amenable to more standard fixation methods. Patients with Sammarco Pattern 1 or 3 (Schon Type 1 or 2) had the best clinical results and the fewest complications. The high prevalence of the Schon beta designation and the substantial amount of dorsal displacement in most patients indicate the severity of the disease in this group.
Sammarco Pattern 5 and Schon Type 3 are the most severe and involve fragmentation of the navicular with involvement of the perinavicular joints. The navicular comminution and fragmentation of the proximal articular surface made it impossible to spare the talonavicular joint. These cases always required arthrodesis of the talonavicular joint, and arthrodesis of the subtalar joint was needed in two patients to achieve stable correction. Complications occurred in six of these seven cases compared with only six of the fifteen that were classified as either Pattern 1 (Schon Type 1) or Pattern 3 (Schon Type 2). Furthermore, four patients with Pattern-5 (Schon Type-3) dislocation had mechanical failure of the medial column screw. Three of these were 6.5-mm screws that broke at the talonavicular joint, and one was an 8.0-mm screw that bent under repetitive load. Some loss of angular correction, especially in the medial column as seen on the lateral radiographs, was seen at the time of final follow-up. While the deformity remained significantly improved as demonstrated by all radiographic measurements at the time of final follow-up, this subset of patients had substantial loss of the initial correction of the talar declination angle and the lateral talar-first metatarsal angle. It is our opinion that this loss of correction was related to mechanical failure of the medial column fixation of the Pattern-5 dislocations. Our results indicate that an 8.0-mm screw should be used in the first ray and that crossing an uninvolved talonavicular joint should be avoided. It is our opinion that Sammarco Pattern-5 (Schon Type-3) deformity does not preclude the use of this technique as successful results were eventually obtained. Patients with this pattern require more careful follow-up and should be informed that there is a higher likelihood of the need for a second procedure.
This technique involves crossing midfoot joints that are not involved in the fusion mass12,13,15,19. Continued motion at these unfused joints resulted in some screw migration and some screw breakage. However, leaving the joints intact lessens the morbidity associated with additional surgical dissection and leaves the subchondral bone plates intact, which affords better screw-thread fixation for compression. We believe that these benefits outweigh the risks of late screw breakage and migration.
We think that ulcers should be treated and allowed to heal prior to the performance of reconstructive procedures. Ulcer management involves off-weighting of the affected area and débridement of necrotic tissue, which harbors bacteria and impairs healing. Osteomyelitis should be treated intensively and should resolve prior to the placement of orthopaedic implants. We do not believe that diabetic foot ulcers can be adequately isolated from the surgical field to prevent contamination of the arthrodesis site or hardware. It is also our opinion that, if an ulcer does not heal with the standard treatments that we have outlined, it is likely that there is an underlying biological problem that has not been resolved, suggesting that aggressive surgical correction with internal fixation may be contraindicated. Those patients may be better served by primary amputation.
The osseous dissolution, fragmentation, and osteoporosis that occur in patients with neuroarthropathic conditions increase the technical demands of midfoot reconstruction. Recurrence of the deformity and nonunion were reported as common sequelae of attempted arthrodesis in earlier series12,13,15,18,19,24. Adequate fixation requires the achievement of purchase in unaffected bone both proximally and distally as well as bridging the area of deformity and bone dissolution. The use of long plantar plates for fixation of these deformities, with the fixation spanning the medial and lateral columns and bridging the arthropathic region, has been described15,19. The plates act in tension during weight-bearing and have been shown to have superior mechanical properties when compared with crossed-screw and more standard dorsal and medial plate techniques. One concern that we have about plantar plate techniques is the amount of soft-tissue stripping needed for exposure. While this technique is promising, additional clinical studies are needed to support its use.
The technique described in this series avoids extensive plantar exposure and facilitates deformity reduction. Osseous resection and alignment of the arthrodesis site are performed under direct vision although with limited exposures. The axial position of the intramedullary screws provides stability and compression of the arthrodesis site, with the avoidance of cortical stress risers that can occur with plates or with obliquely placed screws14. The degree of deformity correction achieved, the maintenance of that correction, and the final fusion rate in this series compare favorably with the results in other published series9,11-13,15,17-19,22,23. Furthermore, all of the patients were able to return to wearing off-the-shelf or extra-depth shoes with an accommodative orthotic device, and there was a relatively low rate of recurrent foot ulceration30,32.
This series demonstrates that surgical correction of neuropathic midfoot collapse with arthrodesis involving utilization of multiple intramedullary axial screws is a viable surgical approach for limb salvage in these patients. 