Tibiotalocalcaneal arthrodesis (TTCA) is a salvage procedure in cases of concomitant severe pathology of the tibiotalar and subtalar joints. Common indications include talar avascular necrosis, failed total ankle arthroplasty, and several severe autoimmune and inflammatory arthropathies. Surgical success is usually achieved in about 80% to 90% of cases, leaving 10% to 20% of cases in need of further management strategies. Some of these remedial strategies include the use of iliac crest bone graft and bone stimulation.1 One less commonly explored management strategy for failed TTCA is the use of a fibular strut graft. Fibular strut grafting was first described by Lexer in 1906.2 The purpose of this paper is to discuss the technique and advantage of the fibular strut graft as an effective salvage in cases of TTCA in high-risk patients and failed primary surgery.
Lateral Exposure and Fibula Harvesting
The patient is positioned supine on the fluoroscopy table with a well-padded tourniquet on the upper thigh. A sandbag is placed under the ipsilateral hip to enhance the visibility of the lateral side of the foot and ankle. A 10 cm curvilinear incision is made over the distal 6 to 8 cm of the fibula, extending inferiorly and anteriorly over the sinus tarsi toward the base of the fourth metatarsal. This creates an inter-nervous plane between the superficial peroneal nerve anteriorly and the sural nerve posteriorly. Full-thickness skin flaps are developed along the skeletal plane. The periosteum is stripped from the fibula anteriorly and posteriorly, and the incision is carried on distally to expose the posterior facet of the subtalar joint and the sinus tarsi. A sagittal saw is then used to create a beveled cut at a 45-degree oblique angle using the desired length of fibula (see Video, Supplemental Digital Content 1, http://links.lww.com/TIO/A6, Video showing harvesting and preparation of fibular graft). The author recommends this cut be about 6 to 8 cm above the talocrural joint. In addition, use of a burr to contour the fibular edges may be undertaken for more smoothness and ease of insertion. The obtained fibular strut is then decorticated, drilled, and its distal end stripped of its cartilage (see Fig. 1, sample fibular strut graft after harvesting, cortical stripping, and drilling). This decortication step is essential to allow invasion of new bone onto the graft for incorporation. Through the same incision, the tibiotalar and subtalar joint are thoroughly prepared in the standard manner. On completion of joint preparation, the foot is placed in neutral ankle position in the sagittal plane, 5 degrees of external rotation in relationship to the tibial crest and 5 degrees of hindfoot valgus while maintaining a plantigrade foot. Temporary fixation using Kirschner wires (K-wire) may be used to achieve appropriate positioning. K-wire positioning must take into account, the later step of reaming and strut graft placement.
Plantar Exposure and Fibular Graft Placement
A guide pin is placed 1 to 2 cm distal from the subcalcaneal fat pad to locate the starting point for fibula nail insertion (if not performed previously). This starting point should be determined using lateral fluoroscopic guidance. Lateral, anterioposterior, and axial views are used to confirm placement after insertion. With satisfactory positioning, a 3 to 4 cm longitudinal incision is made in the starting point on the plantar aspect of the heel pad. Blunt dissection is developed down to the plantar fascia, which is split longitudinally, and then down to the plantar os calcis. A guide wire is inserted through the plantar incision into the calcaneus to pierce the center of the talus and pass 3 or 4 inches up the center of the medullary cavity of the tibia. A series of flexible reamers are used to open the tibiotalocalcaneal canal, reaming to a diameter of 1 to 2 mm larger than the outer diameter of the fibular strut (see Video, Supplemental Digital Content 2, http://links.lww.com/TIO/A7, Video showing insertion of guide pin and reaming for fibular graft). Appropriate foot alignment must be maintained during the reaming step. The fibular graft is then loaded over the guide wire and advanced to flush with the calcaneus using a universal TTC nail extractor (in our case) or a bone tamp/impactor. This should fit the intramedullary (IM) space like a slightly oversized square peg. A few mallet taps may be used to ensure close coaptation and compression of the graft in the IM space (see Video, Supplemental Digital Content 3, http://links.lww.com/TIO/A8, Video showing insertion of the fibular strut graft). Joint immobilization is then achieved using 6.5-mm cancellous screws. The senior author recommends use of at least 2 screws to achieve optimal fixation while avoiding screw contact with the fibular strut graft in order to prevent graft fracture.
RESULTS AND DISCUSSION
Transarticular fibular inlay strut grafting/fibula nail has 3 major advantages: (1) it is an autograft with osteogenic, osteoinductive, and osteoconductive properties; (2) it carries limited morbidity especially because the lateral surgical approach serves to harvest the graft and prepare the joints in the classic manner; and (3) the fibular graft provides mechanical fixation (strut effect) that mimics an IM rod. Although autogenous iliac crest bone graft remains the gold standard and most widely used grafting technique, the reported high rate of complications such as postoperative hematoma, persistent numbness, superficial/deep infections, and chronic pain associated with harvesting the graft can be avoided. The transarticular-free fibular strut graft presents an attractive alternative means to autografting in failed TTCA or in cases of high concern for fusion failure. In particular, atrophic nonunions are one major indication for the fibular strut technique. The use of the technique is especially important for failed IM TTCA in which, the IM space would otherwise be left void. Monaco et al1 reported 2 successful cases of fibular inlay strut grafting following IM nail infection. In another study of patients with posttraumatic arthritis and severe osteopenia, Ebraheim et al3 reported successful use of the IM fibular strut graft technique for TTCA. All 4 patients in that study achieved fusion with no complications reported.
Different techniques other than bone grafting have been described to reduce the nonunion risk when performing TTC arthrodesis particularly in high-risk patients such as those with Charcot arthropathy and diabetes. Some of these techniques include bone stimulation and use of bone morphogenic proteins (BMPs). Bone stimulators have been used in primary and revision hindfoot surgery with Donley and Ward4 reporting a 92% union rate for ankle and hindfoot fusions. Similarly, Bibbo et al5 reported an overall fusion rate of 96% in 112 fusions that received BMPs adjunctively. However, reported associations of BMPs and carcinogenesis deter their widespread use.6 Of note, these adjuvant strategies for high-risk TTCA or failed TTCA are very costly and inaccessible to the average patient.
In our experience, we used the fibular inlay strut graft technique for cases of nonunion, talar avascular necrosis, Charcot deformity, paralytic conditions, rheumatoid arthropathy, infection such as osteomyelitis, and as an exchange nail for failed TTC fusions. In these cases, 81% (13/16) of patients (10 males, 6 females; mean age=54 y; mean BMI=30.4 kg/m2) went on to achieve union as confirmed by computed tomographic scan (see Figs. 2, 3, showing postoperative radiograph and computed tomographic scan in 1 patient). Six patients developed wound dehiscence that was successfully managed by repeat surgical closure (2) or advanced wound care (4). One patient developed intraoperative fracture of the fibular graft (but still achieved union). Of importance, the patient population we targeted for these surgeries were high morbidity patients with such comorbidities as chronic osteomyelitis, Charcot arthropathy with poorly controlled diabetes, and immunocompromised status. This high morbidity is likely responsible for the significant occurrence of wound dehiscence that we encountered. A detailed report of our experience is yet to be published.
Despite the technical difficulties associated with proper fitting of the fibular strut to the reamed IM space as well as the inferior vascularization of the fibular strut (being an avascular autograft), our experience with the fibular strut technique was favorable overall. This technique should be highly considered in cases of failed IM fixation TTCA or cases with high risk for nonunion.
1. Monaco SJ, Lowery N, Crim B. Fibular strut graft
for revisional tibiotalocalcaneal arthrodesis. Foot Ankle Spec. 2016;9:560–562.
2. Lexer E. Die verwedung der freien knochenplastik nebst versuchen uber glenkversteifung und galentransplanen. [The usage of free bone tissue together with joint stiffening and joint transplantation]. Langenbecks Arch Klin Chir. 1906;86:938–942.
3. Ebraheim NA, Elgafy H, Stefancin JJ. Intramedullary fibular graft for tiobiotalocalcaneal arthrodesis. Clin Orthop Relat Res. 2001;358:165–169.
4. Donley BG, Ward DM. Implantable electrical stimulators in high-risk hindfoot fusions. Foot Ankle Int. 2002;23:13–18.
5. Bibbo C, Patel DV, Haskell MD. Recombinant bone morphogenetic protein-2 (rhBMP-2) in high-risk ankle and hindfoot fusions. Foot Ankle Int. 2009;30:597–603.
6. Carragee EJ, Chu G, Rohatgi R, et al. Cancer risk after use of recombinant bone morphogenetic protein-2 for spinal arthrodesis. J Bone Joint Surg Am. 2013;95:1537–1545.
failed tibiotalocalcaneal arthrodesis; inlay; strut graft; Charcot arthropathy; nonunion
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