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Midfoot Fusions: How To Address The Complications
Common complications with midfoot fusions range from infection and nonunion to compensatory joint arthrosis and peripheral nerve issues. Sharing insights from their experience as well as the literature, these authors discuss keys to prevention and management of these complications.
Surgeons commonly use midfoot fusion or arthrodesis to address a wide range of foot pathology, including deformities resulting from neglected or residual clubfoot, paralytic disorders and post-traumatic arthritis. Over the years, podiatric surgeons have also employed the midfoot fusion to address other arthritic conditions including those associated with neuropathy (mainly Charcot neuroarthropathy), seronegative and seropositive arthropathies, neurologic disorders (such as Charcot-Marie-Tooth), and even fractures and dislocations.1,2 All of the aforementioned pathologies can be very painful and debilitating to the patient, and severely restrict foot function.
The goals of midfoot arthrodesis are to achieve a plantigrade foot which is free of pain and which a patient can fit into a shoe.3,4 Wound complications, infection, nonunion, malunions compensatory joint arthrosis, hardware complications and peripheral nerve issues represent the most common post-surgical complications with midfoot fusion.1,2 Accordingly, let us take a closer look at these complications along with their respective prevention and management strategies.
What You Should Know About Wound Complications And Infection
Comprehensive preoperative workup for midfoot fusion requires a thorough history and physical. One should ascertain the healing potential and vascular status of a patient undergoing midfoot fusion prior to surgery. Patient parameters include palpable pedal pulses and non-invasive vascular studies such as the ankle-brachial index (ABI) and transcutaneous oxygen pressure (TcPO2). An ABI of less than 0.80 carries a diagnosis of peripheral arterial disease (PAD) with a 95 percent positive predictive value.2,5 On the other hand, an ABI above 1.00 has a 99 percent negative predictive value for PAD.5
One should also consider an arterial duplex of the involved lower extremity as part of the patient’s vascular workup as it can reveal a broader picture of his or her overall vascular status. When non-invasive vascular studies reveal a diagnosis of PAD, the surgeon should refer the patient to a vascular surgeon for potential revascularization and delay the midfoot fusion surgery until there is an improvement in the vascularity of the limb.
A review of the patient’s medication history is also imperative as some drugs are known to interfere with healing. Methotrexate, immunosuppressive drugs and even non-steroidal anti-inflammatory drugs (NSAIDs) are potential causes of postoperative wound complications.2 While NSAIDs can be useful in the short-term for their analgesic effects, long-term use may delay wound healing via fibroblastic inhibition.6 Long-term steroid use has controversial effects on wound healing as some studies suggest steroids may delay wound healing through decreasing tensile strength, preventing adequate wound contraction and inhibiting collagen deposition.6,7
In addition, adequate nutrition is essential for healing, especially in patients with diabetes. In a study by Zhang and colleagues, poor nutritional status and malnutrition were indicators for worsening diabetic foot ulcerations.8 One can evaluate nutritional status in the preoperative period by assessing serum albumin, total protein, triglycerides and total cholesterol levels.8
The literature shows little consensus on surgical antibiotic prophylaxis.9 However, when the surgery includes hardware, many surgeons use prophylactic antibiotics. Noting that antibiotic prophylaxis is advisable in any surgery involving bone or hardware, and in patients who are immunocompromised or immunosuppressed, Dayton and colleagues recommend administering antibiotics within 60 minutes of making the surgical incision.10 The preferred treatment targets Staphylococcus aureus unless there are additional risks in the patient’s history. One can classify surgical wounds as clean, clean-contaminated, contaminated and dirty.10
The risk of surgical site infection for a clean orthopedic surgery ranges from 0.5 to six percent.9 These infections can occur despite the use of prophylactic antibiotics. The workup for postoperative infection should include laboratory markers such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count (WBC) with differential and imaging studies.
Localized cellulitis may respond to initial treatment with oral or intravenous antibiotics. Purulence, or an abscess, commonly requires a surgical debridement in addition to antibiotic therapy. Whenever possible, the surgeon should not disturb the hardware until fusion occurs. Deep wound cultures and bone cultures can guide antibiotic management. Osteomyelitis may warrant long-term antibiotic intervention.2
When A Patient Has Compensatory Joint Arthrosis
Compensatory joint arthrosis, defined as the development of arthritis in adjacent joints, represents the most common long-term complication following midfoot arthrodesis (see first two photos above). Although one may see evidence of arthritic changes in adjacent joints on radiographic images, not all patients develop symptoms.
Patients with compensatory joint arthrosis should avoid any activity that may cause undue repetitive stresses and joint degeneration. Providers may encourage patients who are either overweight or obese to lose weight. In addition, supportive shoes with accommodative orthoses may help minimize the increased load now borne by the adjacent joints following a fusion. Fusion of the adjacent arthritic joints may be necessary if the patient is symptomatic.2
Ebalard and coworkers reported a higher rate of arthritis in adjacent joints 10 years after subtalar and midtarsal joint arthrodesis.11 However, the study authors found no correlation between the presence of compensatory arthritis, pain, the functionality of the foot and the overall foot architecture.11
Essential Considerations With Nonunion And Malunion After Midfoot Fusion
Nonunion following midfoot arthrodesis reportedly occurs in three to seven percent of cases.12,13 According to the United States Food and Drug Administration (FDA), a nonunion occurs when a minimum of nine months elapses without any clear signs of bone healing for three consecutive months.14 Both intrinsic and extrinsic factors can lead to a nonunion. Poor surgical techniques such as inadequate joint preparation, poor joint apposition and poor hardware constructs can lead to nonunion. In addition, tobacco abuse, malnutrition, poor vascularity and diabetes are among the many risk factors that can also contribute to nonunion.
It is best to address modifiable risk factors along with optimizing the patient’s overall health status prior to surgery. The risk of nonunion is greater in patients who have diabetes, especially those with Charcot arthropathy, in comparison to patients with other pathologies.15
Management of a nonunion following a midfoot arthrodesis depends mainly on whether the patient is symptomatic and whether there is evidence of mechanical instability. Close monitoring and observation are reasonable in the event of a pain-free nonunion with no associated mechanical instability or threats of limb loss. Rocker bottom and extended steel shank shoes represent some of the modalities that one can use to manage an asymptomatic midfoot nonunion as they may assist in preventing motion at the site of concern.2
In addition, the use of braces, cast immobilization and external bone stimulators are viable considerations, especially in those patients who are symptomatic.16
Failure of the aforementioned modalities warrants surgery. The use of bone grafts, including autograft, allograft and other orthobiologics, are advisable when performing revision surgery to augment the fusion site.
In a retrospective study which looked at the effects of fixation type (screws, plates and staples) and the use of bone in tarsometatarsal arthrodesis, Buda and team concluded that the use of isolated plate fixation, smoking during the perioperative period and non-anatomic alignment significantly increased the rate of nonunion in patients who had a tarsometatarsal arthrodesis for midfoot arthritis.17 In addition, they noted the use of autogenous bone graft significantly decreased the risk of nonunion.
A detailed understanding of the lower extremity biomechanics and a proper assessment of the position of the forefoot, midfoot and rearfoot prior to performing a midfoot arthrodesis are key in preventing malunion. In addition, choosing the proper procedure also prevents malunion.2 In general, one can categorize malunions following midfoot arthrodesis based on the plane of the deformity: varus or valgus, dorsiflexion or plantarflexion, and adduction or abduction deformities.
It is important to note that patients may be able to tolerate mild deformities and shoe modification is often all that is necessary to manage such deformities. For instance, those with mild forefoot dorsiflexion can benefit from using a rocker sole shoe while a mild forefoot plantarflexion may respond to heel lifts.
Significant deformity resulting from a malunion, however, requires some type of surgical intervention as these patients often have pain and difficulty fitting in shoes. An osteotomy through the axis of the deformity often suffices to surgically correct a malunion.2
When Hardware Or Peripheral Nerve Complications Arise
Prominent hardware may be a source of significant discomfort, pain and hardware failure such as screw and plate breakage.2 These represent the most common complications of midfoot fusion related to hardware.2 There is a lack of consensus in the current literature on the rate of hardware failure as reports vary considerably.15 Poor fixation constructs and early weightbearing often lead to hardware issues.2 Therefore, proper fixation and an adequate period of immobilization following midfoot arthrodesis can prevent hardware complications. The removal of prominent and painful hardware is common practice for symptomatic relief.
Common peripheral nerve complications following midfoot fusions include neuroma formation, nerve entrapment and neuritis.
Neuritis can occur in as many as nine percent of patients following a midfoot arthrodesis while neuroma formation is present in up to seven percent of patients postoperatively.18 Physical therapy along with the use of neurotropic agents such as the tricyclic antidepressant amitriptyline, anticonvulsants like clonazepam (Klonopin) and gamma-aminobutyric acid (GABA) analogs such as gabapentin (Neurontin) may provide some symptomatic relief in the event of neuritis.2 Resection of neuroma and external neurolysis can address neuromas and nerve entrapment respectively.2
Although rare, complex regional pain syndrome (CRPS) can also occur following midfoot fusion. Early diagnosis and treatment are key to a better outcome. Referral to pain management is warranted if there is a high index of suspicion of CRPS.
When this condition is accurately diagnosed, treatment typically consists of physical therapy, avoidance of any noxious stimuli, the use of oral pharmacologic agents, such as carbamazepine (Tegretol), tricyclic antidepressants and alpha blockers as well as sympathetic nerve blocks.2 Complex regional pain syndrome after midfoot arthrodesis tends to be more prominent in patients who suffered a work-related injury.11
In Summary
Midfoot arthrodesis can address a wide variety of pathologies. When nonsurgical interventions fail to relieve pain and or if there is a risk of joint collapse that may lead to limb loss, one may choose surgical intervention. The goals of surgery should remain to create a stable and pain-free foot with improved function.
Common postoperative complications of midfoot arthrodesis include infection, wound healing complications, nonunion, malunion, compensatory joint arthrosis, hardware issues and peripheral nerve complications. Although these complications may occur in all patient groups, they are much higher in those patients with Charcot neuroarthropathy.15 Accordingly, it is advisable that podiatric surgeons have an elevated awareness of potential complications in this patient population. Good surgical techniques such as proper joint preparation and alignment as well as robust fixation are some of the intraoperative steps a surgeon can take to prevent many of the aforementioned complications.
In addition, we also advocate for the use of bone grafts and other orthobiologics when appropriate. Encouraging smoking cessation for patients is also wise as is optimizing the patient’s nutritional and overall health status in order to facilitate a desired outcome.
Dr. Mvuemba is the Podiatry Clerkship Director at University Hospital in Newark, N.J.
Dr. Metzo is currently the Chief Resident of the Podiatric Residency Program at University Hospital in Newark, N.J.
Dr. Cook is the Director of Podiatric Medical Education at University Hospital in Newark, N.J. He is a Fellow of the American College of Foot and Ankle Surgeons
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