Minimally Invasive Surgery for Tibiotalocalcaneal Arthrodesis Using a Retrograde Intramedullary Nail: Preliminary Results of an Innovative Modified Technique

The Journal of Foot & Ankle Surgery xxx (2016) 1–9

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Original Research

Minimally Invasive Surgery for Tibiotalocalcaneal Arthrodesis Using a Retrograde Intramedullary Nail: Preliminary Results of an Innovative Modified Technique Carlo Biz, MD, Bramir Hoxhaj, MD, Roberto Aldegheri, MD, Claudio Iacobellis, MD Orthopaedic Clinic, Department of Surgery, Oncology and Gastroenterology, University of Padua, Padova, Italy

a r t i c l e i n f o

a b s t r a c t

Level of Clinical Evidence: 4

The aim of the present longitudinal prospective study was to evaluate the clinical, functional, and radiologic outcomes and patient satisfaction of those who had undergone minimally invasive surgery (MIS) for tibiotalocalcaneal arthrodesis with an intramedullary nail. The 28 patients, who had consecutively undergone surgery with the MIS technique, were evaluated clinically and radiographically at 1, 2, 3, and 6 months after surgery and at last follow-up examination. For the clinical evaluation, the American Orthopaedic Foot and Ankle Society scale and visual analog scale for the foot and ankle were used in the preoperative and final follow-up examinations. The patients rated their satisfaction on a scale from 0 to 10. The mean score obtained with the American Orthopaedic Foot and Ankle Society scale was 68.28  5.02 (range 58 to 74) points and with the visual analog scale for the foot and ankle was 70.76  7.72 (range 58 to 82) points, with a mean follow-up of 25.07  6.32 (range 6 to 40) months. The clinical improvement was statistically significant with both types of evaluation (p  .05), comparing the preoperative and follow-up periods. Fusion was achieved in all patients, with a mean fusion time of 14.85  4.12 (range 8 to 56) weeks. The alignment of the ankle and foot was optimal in 27 of 28 patients (96.42%), and patient satisfaction was rated as 6.71  1.37 (range 5 to 10) points. Finally, the use of MIS for tibiotalocalcaneal arthrodesis with intramedullary nail results in fusion of the articulation with a low complication rate. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.

Keywords: ankle fusion calcaneus hindfoot arthrodesis IM nail percutaneous talus tibia

Several options are available for the treatment of pain, arthrosis, instability, and deformities of the ankle and subtalar joints (1,2). However, when debilitating pain or severe deformity of the hindfoot is present, tibiotalocalcaneal (TTC) arthrodesis can be considered as an effective treatment of pain relief and correction of malalignment and is the only alternative to amputation (3,4). To date, a wide range of TTC fusion techniques have been described in published studies, including the use of plates, screws, and intramedullary devices, with or without interposition of bone grafting and performed using different open or arthroscopic approaches (4). Because external fixation is uncomfortable for patients and has been associated with a high rate of nonunion and deep and superficial infection, an internal fixation method has been preferred by many surgeons (5). It allows the achievement of a more stable, rigid fixation and solid union in 74% to 95% of cases, providing good clinical results (6).

Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Carlo Biz, MD, Orthopaedic Clinic, Department of Surgery, Oncology and Gastroenterology, University of Padua, via Giustiniani 2, Padova 35128, Italy. E-mail address: [email protected] (C. Biz).

TTC arthrodesis with a retrograde intramedullary nail was introduced for the first time in 1967 by Kuntscher (7). Subsequently, it was used for post-traumatic arthritis by Kile et al (8) and for Charcot ankle joints by Pinzur and Kelikian (9) and Stone and Helal (10). Since then, different approaches and models of intramedullary nails for arthrodesis of the TTC joint have been proposed. In particular, the use of the nail is indicated for deformities of the rearfoot, arthrosis of the tibiotalar and subtalar joint, infectious arthritis, rheumatoid arthritis, Charcot foot, and in cases of failed total ankle arthroplasty (11–13). However, many patients who have undergone open TTC arthrodesis have shown damaged soft tissue and precarious vascularization, in particular, in cases of the high-risk foot. The large incisions used with open surgical techniques predispose patients to various complications, including infections, neurovascular damage, and poor wound healing (14,15). Different studies have reported nonunion or malunion in patients with diabetes, arthritis, and poor health conditions (16). The use of open surgical techniques for such patients is not indicated. To prevent such complications, surgeons have used the arthroscopic approach (16). This method of arthrodesis has been associated with faster union rates and better overall recovery. Clinical studies have also confirmed a lower incidence of infection and a lower rate of nonunions associated with the arthroscopic approach, although the

1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.06.002

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Fig. 1. Intraoperative images. (A) At the beginning of the procedure, the 2 most commonly used ankle arthroscopy portals and the subtalar portal were marked by a demographic pen, using needles to verify the correct portal joint entry. (B) Finally, a 1- to 1.2-cm vertical skin incision was created for the subtalar portal and anteromedial and anterolateral ankle portals, used for the procedure until suturing.

arthroscopic approach is not indicated for cases of severe misalignment of the hindfoot and significant bone loss of the talus or calcaneus (17,18). This led us to introduce a reproducible minimally invasive surgical (MIS) technique without tourniquet use to perform TTC arthrodesis using an intramedullary nail. The purpose of the present study was to perform a prospective evaluation of a consecutive series of patients treated according to this procedure, reporting on the early results regarding clinical outcomes, radiographic healing rate, complications, functional scores, and patient satisfaction. Patients and Methods Patients All subjects participating in the present study were made aware of the risks and benefits of inclusion and gave their oral and written informed consent for the data to be published. The general clinic directorate of our institution approved the study before we began using the PantaÒ Nail (Integra LifeSciences, Plainsboro, NJ) and started the analysis. The study was performed in accordance with the ethical standards of the 1964 Declaration of Helsinki as revised in 2000. From April 2011 to July 2014, a series of consecutive patients were treated at our institution using the intramedullary retrograde nail locking system and a MIS technique. All patients (100%) were prospectively enrolled in the present case series observational study, and all were available for the follow-up period. Inclusion and Exclusion Criteria The patients were enrolled consecutively over a 3-year period. The following inclusion criteria were used: age 35 to 80 years; severe subtalar and ankle arthrosis, with or without deformities; subtalar and ankle pain that was aggravated when walking or seriously affecting their daily life; failure of >6 months of conservative treatment with pain medication or joint injections and physical rehabilitation; fusion in situ, and provision of informed consent. The exclusion criteria were osteomyelitis, severe osteoporosis, ulceration deep to the fascia, hindfoot deformity requiring osteotomy, and refusal of consent for inclusion in the study.

Intramedullary Nail and MIS Technique All TTC fusions were performed using a retrograde intramedullary titanium (Ti-6AI-4V) nail (PantaÒ Nail, Integra LifeSciences). The nail is available in 4 different lengths (150, 180, 210, and 240 mm) with 4 diameters per length (10, 11, 12, and 13 mm). Bony fixation is achieved using 2 tibial screws, 2 calcaneal screws, and 1 (optional) talar screw. The screws are multiaxially fixed and are fully threaded or partially threaded. Up to 12 mm of compression can be applied using a patented compression/targeting device consisting of a radiolucent frame and metallic support assembled together. Compression rods are used to stabilize the device to the bone and apply compression. The nail also has an autodynamization feature that provides the benefits of initial static compression, allowing the screws to dynamize if shortening occurs. Procedure The senior author (C.B.) performed all the operative procedures using the same technique each time, with the help of 2 different residents of our institution. A prophylactic antibiotic (cefazolin 2 g) was administered before surgery. Thromboembolic prophylaxis with nadroparin calcium was prescribed after surgery until complete weight bearing. Surgery was performed with the patient under spinal anesthesia, in addition to a popliteal nerve block. We avoided applying a tourniquet or any traction methods on the limb. The patient was placed in a supine position on a radiotransparent operating table, with the foot and ankle region protruding from the operating table. This positioning enabled easier maneuvers and better fluoroscopic control during the surgical procedure. The surgical technique involves 2 phases: percutaneous debridement of the articular surface and nail application. Percutaneous Debridement of Articular Surfaces The anterolateral subtalar arthroscopy portal and the 2 most commonly used ankle arthroscopy portals were marked by a demographic pen using needles to verify the correct portal joint entry under fluoroscopic guidance (Fig. 1A). A 1- to 1.2-cm vertical skin incision was made using a no. 11 scalpel for the anterolateral subtalar

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Fig. 2. Intraoperative images. The articular surface in preparation for fusion was initially denuded of the cartilage using surgical chisels first, followed by small osteotomes (A) and a motorized drill (B) with a 5-mm burr (C) under fluoroscopic guidance.

portal first and, subsequently, the anteromedial and anterolateral ankle portals (Fig. 1B), as described by Van Dijk et al (16). After a cutaneous incision approximately 1.5 cm anterior to the middle of the fibula and 1 cm distal to the lateral malleolus, blunt dissection was performed using a mosquito clamp through the subcutaneous tissue into the capsule. No other additional portals were used for debridement of the subtalar joint. Hence, the articular surface in preparation for fusion was initially denuded of the cartilage using surgical chisels first, followed by small osteotomes and a motorized drill with a 5-mm burr under fluoroscopic guidance (Fig. 2). This was done to remove the sclerotic tissue and reach the bleeding and well-vascularized bone. During this procedure, we checked fluoroscopically that the surgical instruments were constantly inside the joint (Fig. 3), as recommended by Carranza et al (19). Next, the osteocartilaginous slurry was removed in part out of the articulation with a small curette. The same procedure was repeated for the articular surfaces of the ankle through the anterolateral and anteromedial ankle arthroscopic portals (Fig. 4), following the same principles described by Carranza et al (19) for the subtalar joint. Applying manual distraction, the ankle joint was opened, and the chisels and burr were orientated to

complete the ankle joint scraping. Thus, the articular surface cartilage of the talar dome, tibia plafond, and a part of the posterior ankle compartment were removed to the subchondral bone. Mild to moderate valgus and varus degrees of deformity were corrected by more internal or external debridement of the lateral or medial surface of the talus, respectively, to achieve an articular surface congruent and suitable for fusion. A small osteotome was placed through both portals to facilitate removal of the osteophytes and create multiple small dimples on the surface of the tibia and the talus to facilitate early bony union. PantaÒ Nail Application Technique Ankle alignment was restored before application of the nail, because the goal of fusion is a neutral position in all patients, with 5 of valgus and 10 to 15 of external rotation. A 2.5-cm plantar incision was made at the optimal insertion site of the intramedullary nail, located at the intersection point of the line passing from the second toe to the calcaneal center and the bimalleolar line. With the ankle blocked in the fusion position, a 3.2-mm Kirschner guidewire with a length of 400 mm was inserted through the

Fig. 3. Intraoperative images. During the procedure, it is crucial to check fluoroscopically that the surgical instruments, in particular, the burr of the drill (A), are constantly inside the joints (B).

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Fig. 4. Intraoperative images. Most of the articular surface cartilage of the tibia and talus at the ankle joint level were removed to the subchondral bone through the anterolateral (A) and anteromedial (B) ankle arthroscopic portal, respectively.

calcaneus and talus under anteroposterior and medial–lateral fluoroscopic guidance until it reached the tibial intramedullary cavity. The subtalar and tibiotalar articular surfaces were reamed over the guide pin. Initially, the planar protection sleeves of 13.5 mm in diameter for a 9-mm diameter reamer were inserted. Next, reaming was started with a 3.2-mm guide. The progression of sequential reaming over the guidewire was controlled fluoroscopically until a final reaming diameter 0.5 mm larger than the implant was achieved. At this point, we proceeded with assembly of the compression device mounted on the nail. The Kirschner guidewire was removed, maintaining the arthrodesis alignment. The intramedullary nail with the support device was positioned manually under fluoroscopic guidance. The intramedullary nail was fixed medially with the supporting device using a Kirschner wire passing transversally through the tibia at the proximal supporting device hole to avoid nail shifts from the correct position. Next, the nail was fixed distally with 2 distal locking screws to the calcaneal bone. Next, we proceeded with the compression device. The proximal tibial Kirschner wire was removed. At this step, the guides for the 5mm reamers were positioned. The green dots for insertion were chosen according to the final implant length (150 mm or 180 mm). Once the holes had been created performed, we removed the reamers and inserted the compression rods. We then proceeded with the compression, gently turning the compression wheel clockwise. The compression could be of a maximum length of 12 mm and controlled fluoroscopically at all times. Once compression was achieved, the intramedullary nail was fixed to the bone with two 3.5-mm diameter screws. First, we reamed the proximal and then the distal hole with a 4.3-mm reamer. The hole length was prepared, and the correct screws were chosen. We removed the reamers and guiding sleeves and applied the screws. The insertion of the screws was done under fluoroscopic guidance. Once the screws were positioned, we removed the targeting and supporting device, and the end cap was screwed into the plantar hole of the nail. We did not use any bone grafting; nor did we perform tenotomy for lengthening of the Achilles tendon in any patient. Postoperative Protocol After surgery, we applied a compression bandage and a nonweightbearing plaster splint for 4 weeks. Finally, the patients were then instructed to walk with partial weightbearing for 6 weeks.

During this period, the patients attended regular clinical and radiologic examinations at our institution. Clinical and Radiologic Evaluation The clinical and radiologic analyses were performed by an independent investigator (B.H.), who was not involved in the treatment of the patients. The preoperative evaluation included complete clinical information (age, gender, side affected, and indication for surgery). Moreover, a thorough physical examination of the leg, ankle, and foot was performed, including the hindfoot alignment and the relation of the calcaneus toward the longitudinal axis of the tibia on the affected side with respect to the unaffected side. The patients were assessed at our institution using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot evaluation system (pain, function, and alignment) and the visual analog scale for the foot and ankle (VAS-FA; pain, autonomy, and functionality of the foot and ankle) (20–22). The patients were also evaluated with routine weightbearing and anteroposterior and lateral hindfoot radiographs. Computed tomography scans were performed when necessary. Postoperatively, the patients attended regular clinical and radiologic examinations at 1, 2, 3, and 6 months after surgery and at the last follow-up point and completed both AOFAS and VAS-FA questionnaires. To determine bone union, the anteroposterior and lateral view radiographs were evaluated for bridging bone/callus formation and the absence of radiolucent lines. Furthermore, no pain on full weightbearing was considered as a predictor factor for complete bone union. The AOFAS and VAS-FA scales both have a total of 100 points (20–22). Additionally, patients were asked to rate their satisfaction with the procedure on a scale from 0 (not satisfied) to 10 (fully satisfied) and to state whether they would undergo the operation again under similar circumstances (yes or no). Complete joint fusion was determined through anteroposterior and lateral view radiographs showing total bridging with absence of radiolucency. Statistical Analysis The statistical analyses were performed by an independent statistician (Anna Chiara Frigo, Department of Statistics, University of Padua). The results of these variables were summarized as the arithmetic mean  standard deviation and median for continuous variables and as counts for the categorical measures. The present

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study was a longitudinal prospective study. We used the Shapiro-Wilk test to evaluate the normal distribution of the variable of the preoperative and postoperative scores obtained using the AOFAS and VASFA scoring systems (20–22). The statistical variation between the preoperative and follow-up AOFAS and VAS-FA scores was performed using the Student t test for paired samples. We separated our patients into 2 groups: those affected by post-traumatic arthrosis and those without trauma or fractures. The variation of preoperative and followup AOFAS and VAS-FA scores among the patients with and without trauma was examined using the Student t test for unpaired samples. We used p  .05 to detect statistically significant differences between the mean values. Results A total of 28 consecutive patients met the inclusion criteria of the study, including 18 patients (64.28%) with post-traumatic arthrosis, 6 (21.42%) with primary arthrosis, 2 (7.14%) with Charcot foot, and 2 (7.14%) with congenital deformity of the hindfoot. The participants included 22 males (78.5%) and 6 females (21.42%), with a mean age of 52.20  12.02 (range 35 to 80) years and a mean weight of 79.07  16.04 (range 47 to 138) kg at surgery. The mean American Society of Anesthesiologists classification was 2.25  0.65 (range 1 to 3) points. Of the 28 patients, 12 (42.86%) were affected on the right foot and 16 (57.14%) on the left foot. The mean duration of surgery was 80.16  8.12 (range 60 to 150) minutes, and the mean hospitalization stay was 5.42  0.78 (range 3 to 8) days. Our follow-up protocol lasted a mean of 25.07  6.32 (range 6 to 40) months. The patient data are summarized in Table 1. Fusion was confirmed clinically and radiographically in all 28 patients (100%) at a mean period of 14.85  4.12 (range 8 to 56) weeks postoperatively. One patient (3.57%) had delayed radiologic consolidation with associated pain. Of the 28 arthrodeses (100%) performed, 25 good results (89.28%) and 3 fair results (10.71%) were achieved. No patient reported a poor result (Figs. 5 and 6). The mean preoperative AOFAS hindfoot score was 26.14  4.07 (range 20 to 34) points, and the mean postoperative score at the last follow-up point was 68.28  5.02 (range 58 to 74) points, for a mean increase of 42.14 points. The difference was statistically significant (p  .05; Fig. 7). The same improvement was seen with the VAS-FA scale (Fig. 8), with a preoperative score of 27.78  3.98 (range 20 to 34) points and a postoperative score of 70.76  7.72 (range 58 to 82) points. The improvement in the score was 42.98 points, which was also statistically significant (p  .05). Between the 2 groups of patients, those with and those without post-traumatic arthrosis, no statistically significant differences (p  .05) were seen in the improvement between the preoperative and postoperative AOFAS hindfoot scale and VAS-FA scores. One patient (3.57%) experienced abnormal ambulation, but none had severe restriction of daily activities. The alignment of the rearfoot and ankle was plantigrade and stable in 26 patients (92.85%). One patient (3.57%) underwent fusion in an equinus position intentionally because of bone loss.

Table 1 Demographics and characteristics of patients who underwent tibiotalocalcaneal surgery Patient Data

Mean  SD

Age (y) Gender (male:female) Weight (kg) ASA points Duration of surgery (min) Follow-up (mo)

52.20 22:6 79.07 2.25 80.16 25.07

 12.02    

16.04 0.65 8.12 6.32

Abbreviations: ASA, American Society of Anaesthesiologists; SD, standard deviation.

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The patient mean satisfaction score was 6.71  1.37 (range 5 to 10) points on the 0- to 10-point grading scale and 26 patients (92.9%) stated that they would undergo the operation in a comparable situation. At the latest follow-up point, which included both AOFAS scale and VAS-FA evaluation, 2 patients (7.14%) reported persistent pain. The VAS-FA revealed that 28 patients (100%) were satisfied with their mobility at the last follow-up point. The results for our cohort are summarized in Table 2. Most complications were classified as minor. Screw protrusion was observed in 1 case (3.57%) and exostosis in 3 patients (10.71%). Major complications such as nonunion of the articulation and damage to the neurovascular structures were not observed. Improper alignment of the hindfoot was detected in 1 patient (3.57%), who had experienced significant bone loss. The foot was fused in equinus by the surgeon, owing to the lack of bone. No issues related to surgical wounds developed. None of the patients had painful degenerative arthritis (grade 4, according to Kellgren and Moore) of the midtarsal joints at the final follow-up point. Eighteen patients (64.28%) had no difficulty in walking 4 blocks. Discussion TTC arthrodesis is a standard effective procedure for patients with severe hindfoot pain due to end-stage arthrosis, severe instability, or deformity with no response to conservative treatment (23). In particular, combined arthrodesis with intramedullary nail fixation is considered a salvage procedure that has also become a primary approach for post-traumatic osteoarthritis, congenital defects, infectious arthritis, rheumatoid arthritis, ankle and subtalar joint tuberculosis, neuromuscular disorders, and Charcot neuroarthropathy (1,24). Different investigators have shown reasonable results with open TTC arthrodesis, demonstrating the effectiveness of this surgical method in a multicenter study (25–27). The main objective of the TTC arthrodesis is to gain ankle stability and pain relief and maintain hindfoot function, thus allowing patients to perform daily activities relatively quickly. This has been the reason surgeons have previously preferred generous incisions to achieve good exposure of articular surfaces. However, the most feared complication for surgeons performing this type of surgery is poor fusion and bone infection (28). In our study, the objectives remained the same, but with greater stability, early weightbearing, increased function, and diminution of the complication rate. To the best of our knowledge, the present study involved the largest sample of patients treated with TTC arthrodesis using a minimally invasive technique, achieving functionally (AOFAS and VAS-FA) and radiologically (100% fusion) good results, superior to both conventional (open) techniques and arthroscopic procedures reported in published studies (25,29). Many patients treated at our institution in the past using the open approach developed major complications such as infection, slow articular fusion or nonfusion, improper alignment, neurovascular damage, nonhealing scars, the persistence of severe pain, and stress fractures. This led us to develop the technique of TTC arthrodesis using a MIS technique from our experience in MIS forefoot deformity corrections. To the best of our knowledge, no previous studies have used minimal incisions to perform MIS TTC arthrodesis with an intramedullary nail such as we have described. The primary issue of open surgery is the risk of major complications, in particular, soft tissue damage associated with neurovascular lesions leading to high complication rates, reported to be about 43% (30,31). It has been reported that patients undergoing open surgery have a complication rate of 60%, and another study showed that 7.9% of patients developed infection (31). The complication rate has been lower after arthroscopy surgery (16,32). However, the MIS technique

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Fig. 5. Case 1: a 36-year-old female patient with primary arthritis. Preoperative anteroposterior (A) and lateral (B) radiographs and postoperative anteroposterior (C) and lateral (D) radiographs at the 1-month follow-up point. Anteroposterior (E) and lateral (F) radiographic views at the 3-month follow-up visit showing complete fusion of the hindfoot.

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Fig. 6. Case 2: a 44-year-old female patient with post-traumatic arthritis. Preoperative anteroposterior (A) and lateral (B) radiographs and postoperative anteroposterior (C) and lateral (D) radiographs at the 1-month follow-up visit. Anteroposterior (E) and lateral (F) radiographic views at the 2-month follow-up visit showing complete fusion of the hindfoot.

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Table 2 Preoperative data versus postoperative data of patients who underwent minimally invasive tibiotalocalcaneal surgery Data (mean  SD) Fusion (wk) Satisfaction (points) AOFAS (points) VAS-FA (points)

Preop (mean  SD)

Postop (mean  SD)

p Value

26.14  4.07 27.78  3.98

68.28  5.02 70.76  7.72

 .05*  .05*

14.85  4.12 6.71  1.37

Abbreviations: Postop, postoperative; Preop, preoperative; SD, standard deviation. * Statistically significant.

Fig. 7. Graph of the statistical analysis results of the pre- and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale scores (p  .05).

used in the present study had a total complication rate of 28.56% and was associated with a very low risk of soft tissue and neurovascular damage. This positive outcome resulted from maintaining the surgical instruments within the tibiotalar and talocalcaneal joint (the safe zone) using fluoroscopic guidance. No cases of neurovascular or soft tissue damage occurred in our study. We used the same portals used in arthroscopy to introduce our surgical instruments, allowing an excellent approach to the ankle joint and reducing the risk of neurovascular injury (16). However, the arthroscopic technique provides the advantage of joint visualization and requires no irradiation. Moreover, our technique avoids the extravasation of fluids, which can cause compartment syndrome. We had good clinical outcomes with the MIS technique for TTC in 1 patient with bone loss and in 3 patients with severe post-traumatic osteoarthritis, conditions that are contraindications for the arthroscopic technique. We believe the MIS technique for TTC could have vastly more indications than the arthroscopy technique has at present. The MIS technique produces osteocartilaginous slurry (a hemopoietic tissue), which we believe is beneficial in producing new bone tissue, thus achieving faster bone fusion (17,33). We strip the cartilage from the joint surface, promoting angiogenic–osteogenic coupling. Different studies have demonstrated that osteoblasts can differentiate under local factor stimulation such as biomechanical

Fig. 8. Graph of the statistical analysis results of the pre- and postoperative visual analog scale for the foot and ankle (VAS-FA) scores (p  .05).

stimuli and partial pressure of oxygen, thus inducing bone formation (34). The other method we use to stimulate bone formation is minimal periosteal stripping from the subchondral bone, leaving the bone–vascular tissue beneath. This tissue generates periosteal mesenchymal stem cells that assist in bone healing (35). We had 3 cases with bone formation from the osteocartilaginous slurry extravasated from the joint. We used the MIS technique for 2 reasons. First, to avoid making large incisions on poorly vascularized tissue, therefore avoiding poor scarring and infection of the soft tissue and bone; and, second, to keep the osteocartilaginous slurry within the articulation to increase the bone metabolism without the need for additional autogenous or allogenic bone grafts. We had no evidence of nonunion in the patients in our study. The nonunion rate observed with open techniques was reported to be 22% by Chou et al (27). We believe this resulted from the use of osteocartilaginous slurry, periosteal stripping from the subchondral bone, and good compression between the bones. The mean fusion time achieved with the MIS technique was 14.85  4.12 (range 8 to 56) weeks, indicating fast fusion. One patient (3.57%) required a longer fusion time (56 weeks) because of bone loss and heavy smoking. We attributed the high fusion rate and quick fusion time to the use of the osteocartilaginous slurry, the better vascularized tissue with less soft tissue damage, and the lower infection rate. Another important factor for achieving this result is the use of the posteroanterior calcaneal interlocking screw, which gives better compression to the articulation and greater rotational stability compared with a transverse screw. One patient (3.57%) experienced misalignment after TTC in our study. The results we obtained were comparable to those from different studies of TTC using open techniques (36). To determine the optimal insertion point of the TTC nail, different radiographic images and clinical scientific studies have been performed (37,38). The ideal position of the foot and ankle before insertion of the intramedullary nail should be with the ankle neutral in a 90 dorsal flexion/90 plantar extension, with 5 valgus of the calcaneal bone in the frontal plane and 10 to 15 external rotation of the foot (39). This position of the rearfoot along the leg is difficult to achieve (40–42). During application of the intramedullary nail (PantaÒ nail, Integra LifeSciences) in the TTC joint, different anatomic structures can be damaged, including the plantar lateral neurovascular bundle and the plantar lateral nerve bundle. Different studies have shown that the optimal insertion point of the intramedullary nail is located lateral to the medial line of the calcaneal bone. The longitudinal bisection line of the calcaneal bone is located 5 to 10 mm laterally of the bisection line of the tibia (38,43). To perform TTC arthrodesis, the foot should be displaced medially to achieve alignment of the 2 bisection lines. The medial dislocation of the foot achieves a colinear relation of the tibial and calcaneal bisection, reducing the risk of damage of the neurovascular bundle and increasing the stiffness of the calcaneal bone fixation (38,43). Also, the second step of this technique, in addition to ensuring strong compression and great stability, offers the advantage of maximal soft tissue preservation of the plantar aspect of the foot.

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All the patients were treated by the same surgeon, the senior author (C.B.), avoiding variability and obtaining more reliable data. In our study, patients with poorly vascularized soft tissue were included, extending the indications for this surgical technique. Our study had several limitations, including the limited number of patients involved in the study with a nonoptimal distribution of the obtained data. Moreover, this type of surgery cannot be recommended for all pathologic entities of the hindfoot. Further evaluation of the proper indications should be conducted. Some patients had a short follow-up period, making the evaluation of the side effects of the surgery not entirely certain. The clinical and radiographic evaluation was performed by a single operator, who had not been involved in operative treatment, with no second operator as a control. This might have led to an overestimation of the data, although the operator was properly educated before collecting the data. The MIS technique has a long learning curve. The surgeon who performed the surgery has specialized in foot orthopedic surgery and has a long experience with the MIS technique. Thus, the results obtained in our study should be compared with those from studies conducted by surgeons with the same or superior experience. We believe that, before starting this technique, surgeons should have an optimal understanding of foot and ankle anatomic pathologic features. In conclusion, our preliminary data have demonstrated that this combined technique consisting of minimally invasive surgery for debridement of articular surfaces, associated with the use of a compressive retrograde intramedullary nail, allows successful and safe achievement of the clinical and radiologic goals of a stable and early TTC arthrodesis, thus minimizing the occurrence of the common complications of traditional procedures. Acknowledgments The authors acknowledge Professor Anna Chiara Frigo for her assistance with the statistical analysis. References 1. Adams JC. Arthrodesis of the ankle joint: experiences with the transfibular approach. J Bone Joint Surg Br 30:506–511, 1948. 2. Baciu CC. A simple technique for arthrodesis of the ankle. J Bone Joint Surg Br 68:266–267, 1986. 3. Reckling FW. Early tibiocalcaneal fusion in the treatment of severe injuries of the talus. J Trauma 12:390–396, 1972. 4. Katsenis D, Bhave A, Paley D, Herzenberg JE. Treatment of malunion and nonunion at the site of an ankle fusion with the Ilizarov apparatus. J Bone Joint Surg Am 87:302–309, 2005. 5. Thordarson DB. Fusion in posttraumatic foot and ankle reconstruction. J Am Acad Orthop Surg 12:322–333, 2004. 6. Goebel M, Muckley T, Gerdesmeyer L, Militz M, Buhren V. Intramedullary nailing in tibiotalocalcaneal arthrodesis. Unfallchirurg 106:633–641, 2003. 7. Kuntscher G. Combined arthrodesis of the ankle and subtalar joints. In: Practice of Intramedullary Nailing, pp. 207–209, edited by RH Trans, Charles C. Thomas, Springfield, IL, 1967. 8. Kile TA, Donnely RE, Gehrke JC. Tibiotalocalcaneal arthrodesis with an intramedullary device. Foot Ankle Int 15:669–673, 1994. 9. Pinzur MS, Kelikian A. Charcot ankle fusion with a retrograde locked intramedullary nail. Foot Ankle Int 18:699–704, 1997. 10. Stone K, Helal B. A method of ankle stabilization. Clin Orthop Relat Res 268:102– 106, 1991. 11. Royer C, Brodsky JW. Arthrodesis techniques for avascular necrosis of the talus. Tech Foot Ankle Surg 1:50–59, 2002. 12. Caravaggi C, Cimmino M, Caruso S, Dalla Noce S. Intramedullary compressive nail fixation for the treatment of severe Charcot deformity of the ankle and rear foot. Foot Ankle J 45:20–24, 2011. 13. Makwana NK, Morrison P, Jones CB, Kirkup J. Salvage operations after failed total ankle replacement. Foot 5:180–184, 1995.

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