- In a retrospective review spanning nearly 20 years, tibial stress fracture was noted to be a rare complication of ankle arthrodesis, occurring in only 15 of 1,046 patients (1.4%)
- Notably, stress fractures occurred as early as three months and as late as 25 years following the index surgery, averaging about 42 months post fusion when they happen
- Almost universally, the heralding clinical presentation was onset of focal pain at the site of stress fracture
- Following diagnosis and treatment, all patients had healed well by final follow-up, including those managed conservatively as well as four patients who required operative intervention
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For patients with end-stage ankle arthritis, ankle arthrodesis (fusion) is highly likely to result in pain relief and improved function. However, reports do exist of delayed onset tibial stress fracture occurrence following otherwise successful ankle arthrodesis. Fortunately, however, this complication is quite rare and is typically the result of stress overload, poor remaining bone quality and/or localized stress risers from the indwelling hardware.
Christopher W. DiGiovanni, MD, chief of the Foot and Ankle Center at Massachusetts General Hospital, Mohamed Abdelaziz Elghazy, MD, PhD, of Mansoura University, and colleagues recently found that distal tibial stress fracture is a rare event after ankle arthrodesis, occurring in just 1.4% of patients. Their report in Foot and Ankle International emphasizes that such fractures can occur years or even decades after the surgery, regardless of the type of ankle fixation hardware.
The research team retrospectively reviewed patient records from 1990 to 2019, including patients treated at several hospitals in both Boston, MA (Mass General and Newton Wellesley Hospitals) and Providence, RI (several Brown University-affiliated hospitals). All patients having undergone ankle fusion over this period were included, specifically looking for anyone who subsequently developed a stress fracture of the tibia following either ankle fusion or tibiotalocalcaneal (TTC) arthrodesis.
In addition, patients at Mass General who presented with a stress fracture after ankle or TTC arthrodesis between January 2018 and April 2019 were followed prospectively.
Prevalence and Timing of Stress Fracture
Of 1,046 patients reviewed, 15 (1.4%) developed a tibial stress fracture. The index surgeries had been:
- Isolated ankle arthrodesis (n=8)
- Ankle arthrodesis following successful subtalar fusion with resultant ankle nonunion that required revision TTC nailing (n=3)
- Ankle arthrodesis subsequent to a prior successful subtalar fusion (n=2)
- Primary TTC arthrodesis (n=2)
Tibial stress fracture occurred in the face of multiple different fixation constructs: screws only, plate and screws, or intramedullary nailing. It also occurred following both open and arthroscopic approaches.
The average time from the index surgery to stress fracture presentation was 42 months, with a range of 3-300 months.
Diagnosis of Stress Fracture
All patients presented with distal tibial pain which localized to the site of stress fracture. The onset of symptoms was sudden in three patients.
The stress fracture was evident on plain radiographs in 10 patients. Two patients required additional MRI for diagnosis, and one patient was diagnosed after computed tomography and one other following bone scan. A final patient had negative radiographs, MRI and bone scan, but was eventually diagnosed and treated on the basis of clinical suspicion (focal pain and swelling at a region just above prior hardware for fusion).
Potential Risk Factors
- None of the patients reported a relevant traumatic event
- In nine patients, the fracture occurred at the level where the fibula was resected or osteotomized, so increased biomechanical forces transferred to the tibia may have been a factor
- Eight patients had osteopenia
- In nine patients, the stress fracture was located just proximal to the location of the prior ankle fusion fixation hardware
One patient who had a displaced fracture underwent immediate plate fixation, but all others were initially treated with immobilization and activity modification. Three of those 14 patients failed to improve following a minimum of three months of conservative management and eventually underwent elective operative fixation of the fracture using either intramedullary nailing or tibial plating. All patients reported significant pain improvement and were healed at final follow-up.
- Be suspicious of ankle and lower leg pain in delayed onset following ankle fusion, especially when activity or weight bearing related: Due to the delay in presentation of a tibial stress fracture, maintain a high level of suspicion when patients present with pain at the ankle or lower third of the leg following ankle or tibiotalar arthrodesis, even if successful union was achieved
- Utilize advanced imaging: If plain radiographs are negative but the patient's focal symptoms do not improve after a short period of immobilization, obtain a CT scan or MRI. If that imaging is negative but clinical suspicion remains high, a bone scan may be necessary
- Nonoperative management: There is little downside in attempting nonoperative management as long as the fracture is non or minimally displaced
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