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A 69-year-old woman with right ankle pain
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A 69-year-old woman with a history of hypothyroidism, depression, high blood pressure and sleep apnea presented to our office with right ankle pain. She reported a history of pes planus and ankle osteoarthritis for which she underwent a pantalar arthrodesis via tibiotalocalcaneal intramedullary nail to the right ankle 1.5 years prior to presentation which never resolved her pain or deformity. Her postoperative recovery and physical therapy regimen were unremarkable; however, once completed approximately 7 months after the operation, she noted a lack of improvement from her preoperative state. She subsequently developed increasing pain to the right ankle, limiting her function and ability to perform her activities of daily living. She stated she could no longer live her life with this amount of pain and was looking for the best option to alleviate her discomfort.
Physical examination revealed the incisions to be intact with no signs of infection. Her right side had a significant pes planus deformity with her calcaneus in significant valgus. She had limited range of motion at the ankle joint and within the midfoot. There was no palpable defect along the anterior tibia where she reported anterior leg pain; however, a palpable fullness was appreciated on the plantar aspect of her foot that seemed to correspond to the distal aspect of the intramedullary rod. Her neurovascular exam was normal throughout. Radiographs (Figures 1 and 2) revealed an IM nail in place traversing the subtalar and tibiotalar joints. The distal screws were broken and the hindfoot maintained a significant valgus position.
AP radiograph shows tibiotalocalcaneal intramedullary device in place within the right tibia. Broken hardware is noted distally.
Lateral radiograph demonstrates broken distal screws, as well as a prominent nail at the plantar calcaneus.
Images: Bitterman A
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Right ankle subtalar joint nonunion after previously attempted TTC fusion
This patient experienced a nonunion of her right subtalar joint, as well as broken hardware that caused loosening of the IM rod within her right tibia. Her situation was complicated by her preoperative foot posture. Her pes planovalgus deformity may have contributed to the incorrect positioning of the rod with a medial entry point resulting in a missed calcaneus.
In the setting of tibiotalar and subtalar arthritis, various surgical options exist to promote fusion of these joints. The use of a tibiotalocalcaneal (TTC) nail has demonstrated promising results with many patients experiencing pain relief and correction of their deformity. The TTC nail is frequently a limb salvage procedure and a promising option for patients who may otherwise require other debilitating surgical intervention. Successful limb salvage rates have been reported at 88%, with union rates ranging from 80% to 88%.
Complications
Despite the relative success of TTC fusion, various authors have highlighted the risks and complications associated with this procedure. While amputation may be the most feared and debilitating outcome, more common complications include delayed wound healing, superficial and deep infection, delayed union, malunion and nonunion. Each complication would serve as a potential precursor to future amputation. While amputation may be the more feared outcome, nonunion is more common and a difficult diagnosis to treat.
Reasons for nonunion are variable, though in the absence of infection, the principles of compression, alignment and motion are essential. While an internal compression mechanism may be beneficial, proper alignment must first be obtained in order to compress across the joint. Correct placement of the TTC nail to include the calcaneus provides proper placement of the calcaneus under the talus. Without this positioning, valgus deformity, depending on pre-existing condition, is likely to persist.
Motion between the proximal and distal fragments also is important to consider. A biomechanical study looking at TTC arthrodesis found the use of three crossed cancellous screws provided the most rigid fixation and the least micromotion of the tested techniques. The authors noted, however, augmentation with a tibiotalar staple confered nearly equal stability to the three screw technique. Similar to the principles of fracture healing, compression and reduction of micromotion across the defect are important for primary bone healing to occur. When encountering patients with a subtalar nonunion, compression, alignment and reduction of micromotion can be applied to fixation of the subtalar joint.
Successful TTC fusion can be achieved via ring external fixation, plate and screw constructs, as well as IM devices. Authors have described success with the use of ringed external fixators in revision tibiotalar arthrodesis and have demonstrated success in patients that would have otherwise been contraindicated for internal fixation. Another option is the modified use of a 3.5-mm proximal humerus locking plate. Success in achieving stability and a high rate of union (94.1%) has been demonstrated using this technique. Given the risk for potential complications and the wide variety of techniques described to treat a TTC fusion, subtalar nonunion following primary TTC arthrodesis is a challenging diagnosis to treat.
We recommend incorporating multi-use compression screws due to their ability to provide rigid fixation and compression across the subtalar joint. They can be applied using minimally invasive techniques, an important consideration in patients with several comorbid conditions. Use of augments, including a bone stimulator, also should be considered, especially in patients undergoing revision after a failed fusion attempt.
Treatment
Further diagnostic testing was performed. The patient underwent a CT scan of the lower extremity in order to better identify the hardware placement and to better identify the fusion sites and the bone stock of her right leg. The CT demonstrated nonunion of the subtalar joint with the nail having limited contact with the calcaneus (Figure 3). Three-phase bone scan did not reveal any suspicion of infection surrounding the previously implanted hardware. Laboratory studies to identify infection were all within the normal range.
The CT scan and clinical exam confirmed the tibiotalar joint was sufficiently fused and did not require further manipulation. The subtalar joint did not have an adequate fusion bridge, consistent with nonunion. The decision was made to perform a triple arthrodesis after removing the previous hardware and correcting the malalignment. Using fluoroscopic guidance, the broken screws were identified and removed. The IM rod was then cannulated and removed. There was no significant change in the patient’s bone stock following hardware removal. Attention was then drawn to the subtalar, talonavicular and calcaneocuboid joints. Each was appropriately distracted in order to denude any remaining native cartilage using curettes and osteotomes. The subchondral bone was then perforated on either side of the joints. Biologic augmentation via AlloMatrix (Wright Medical) was utilized as bone graft to supplement the resulting bone voids. These joints were then re-positioned and pinned in such a manner to create a plantigrade foot. Multi-use compression screws (Wright Medical) were placed across the subtalar joint. The talonavicular and calcaneocuboid joints were then fixed using smaller multi-use compression screws. With the assistance of intraoperative fluoroscopy, adequate compression was visualized and appropriate length of all implanted hardware was confirmed.
Approximately 2 weeks after the surgery, the patient’s wounds were healing well (Figure 4). There was no evidence of any infection to the previous incision sites or those created from her revision surgery. Her pain had improved drastically and she was pleased with the improved position of her foot. She is currently 6 months removed from her operation and doing well, weight-bearing on the right leg without any discomfort and actively participating in physical therapy.
- References:
- Ahmad J, et al. Foot Ankle Int. 2007; 28(9):977-983.
- Bennett GL, et al. Foot Ankle Int. 2005; 26(7): 530-536.
- DeVries JG, et al. Foot Ankle Int. 2013;doi: 10.1177/1071100712472488
- Easley ME, et al. J Bone Joint Surg Am. 2008;doi: 10.2106/JBJS.G.00506.
- Taylor J, et al. Foot Ankle Int. 2015;doi: 10.1177/1071100715611891.
- Thomas R, et al. J Am Acad Orthop Surg. 2012;doi: 10.5435/JAAOS-20-01-001.
- For more information:
- Eric R. Barnard can be reached at ebarnard@wakehealth.edu.
- Adam Bitterman, DO, and Johnny Lin, MD can be reached at 1611 W. Harrison St., Suite 300, Chicago, IL 60612. Bitterman’s email: adam.bitterman@gmail.com. Liu’s email: johnny.lin@rushortho.com.
Disclosures: The authors report no relevant financial disclosures.