Essential Insights For Managing Nonunions

Nonunions can be a troubling condition for both the patient and the podiatric physician. Failed unions can result from a host of factors arising from the patient, surgeon or both. In many surgical cases, one primary cause is difficult to identify and the end result may actually result from a combination of various etiologies. As with any surgical complication, it is important to emphasize preventive efforts. However, even with diligent efforts, a nonunion may still occur. In my opinion, there are three different perspectives that dictate how one should treat. There is the academic perspective, the patient perspective and the podiatric physician’s perspective. From a purely academic point of view, a non-union is classically described as a fracture, osteotomy or arthrodesis site that has failed to show progressive signs of radiographic healing over an eight-month period. However, almost every surgeon will agree this is more of a guideline than a concrete statement. When a fracture, osteotomy or arthrodesis site fails to progress toward a successful union, surgeons will often treat this aggressively prior to the conclusion of an eight-month time frame. From the patient’s perspective, the condition may not even require treatment. In many cases, a surgical or traumatic non-union may not cause pain or alter function, and is simply a radiographic finding. If there is appropriate discussion with the patient and documentation, one may forgo treatment of the nonunion. The perspective of the podiatric physician is most important as he or she is considering what is the most beneficial thing for the patient in the long term. For example, a nonunion of a first metatarsocuneiform arthrodesis may not be symptomatic but gradual elevation of the first ray can lead to transfer pressure and lesser metatarsal complications. In such cases, even a pain-free nonunion may require treatment in order to prevent long-term sequela. Emphasizing Patient Compliance In Preventing Nonunions Despite a surgeon’s (and the patient’s) best efforts, nonunions can still occur. However, there are several factors that surgeons and patients can address during the pre-operative or pre-treatment period that will reduce the risk of a failed union. For the sake of simplicity, one may divide these factors into patient factors and surgeon/physician factors. Obesity is a common dilemma and can contribute to a myriad of health problems. Any type of bony injury or reconstruction can be significantly influenced by a patient’s weight. The added weight can make it difficult for the patient to remain compliant in treatments that necessitate complete non- or protected weightbearing. Postoperative or post-traumatic edema can also be exacerbated by the increased weight. It has also been my experience that fitting overweight patients in non-custom devices for the purpose of offloading or immobilization is difficult. Concurrent health problems such as diabetes do not always preclude surgical intervention but one should strive to do what he or she can to minimize the potential effects of these conditions. In particular, when patients have diabetes, one should emphasize the importance of strong glucose control even if the clinician is initiating conservative treatment. Patients on chronic steroid therapy and other immunosuppressive medications may also need to have adjustments to their dosages. Compliance is difficult and, at times, impossible to control. Early or excessive weightbearing can displace internal fixation or increase micromotion of bony fragments, and increase the chances of nonunion. Casting, bracing or in-patient admission, if warranted, can dictate some of the patient’s activities but, ultimately, having a frank discussion with the patient about possible adverse outcomes is the most influential way to facilitate compliance. Revisional surgery is not a pleasant proposition for the surgeon or patient. Key Preventive Measures For Reducing Nonunion Risk Conservative treatment and the choice of surgical procedure will vary among physicians and surgeons. However, there are certain principles we typically adhere to when attempting to prevent or reduce the incidence of nonunion. In my opinion, immobilization can be overzealous. Most surgeons will agree that immobilization is needed for fracture treatment and many arthrodesis or osteotomy procedures. Of course, the question is “How much immobilization is enough?” This can vary among surgeons. Some argue for early range of motion but others feel the possibilities of atrophy and loss of motion are outweighed by the increased chance of a delayed or nonunion. Ultimately, the surgeon has an obligation to consider several factors such as patient health, the procedure he or she performs and the stability of fixation in order to determine what is appropriate for each patient. Six to eight weeks seems to be an appropriate minimum time frame for immobilization in the majority of patients. Periods of immobilization longer than this time frame may be needed in some cases but often necessitate prolonged and aggressive therapy and still may not allow an optimum return to activities. Fixation has continued to change significantly over the past several decades. New advances have chiefly focused on facilitating quicker healing times and a more rapid return to weightbearing. Indeed, external fixation has gained a large foothold in the arena of foot and ankle reconstruction due to a greatly diminished or even a lack of an initially limited weightbearing period. Not only should fixation focus on stability but one’s surgical technique should focus on minimal disruption of the soft tissue envelope. In many cases, excessive exposure for the sake of greater fixation may not benefit the patient. Podiatric surgeons can often use external fixation solely or in conjunction with internal fixation to limit soft tissue injury. In very limited cases, I have found that external fixation, which promotes stability and compression, can negate the need for open resection of non- or delayed unions. Post-Op Management: What You Should Know Postoperative management can literally make or break any type of surgical procedure. Although topics such as stress shielding and cast disease seem to be increasingly discussed in the surgical arena, rarely can one find fault with a protective and conservative postoperative course. Conservative treatment of a nonunion can involve immobilization and external bone stimulation. Although casting alone remains a vital tool in the treatment of a delayed union, a nonunion usually requires more than simply a longer period of immobilization. External bone stimulation continues to be a mainstay in the non-operative treatment of nonunions. Some devices employ electric fields while others cause micromotion within the nonunion site through ultrasound. Whichever method the podiatric surgeon chooses, the sooner one initiates the device, the greater the chances of healing the problem site. Typically, one would start external bone stimulation well before a nonunion has been confirmed via radiograph. Some podiatric surgeons may argue that bone stimulation does not allow healing in a true nonunion of eight months or greater duration. This depends on the type of nonunion that the patient has developed. I have had limited success using bone stimulation to treat hypertrophic nonunions in which neovascularization is still possible. In atrophic nonunions, the possibility of a bone stimulator initiating healing is significantly reduced. Surgical treatment of a nonunion has continued to evolve over the past decade. When it comes to resection of the nonunion site and fixation through internal and/or external means, the goal is restoring well vascularized bone segments and avoiding motion that limits bone formation. External fixation can provide success in select cases of nonunions that require immobilization and significant amounts of compression. These techniques may allow surgeons to refrain from reopening the original surgical site or otherwise significantly limit the necessary exposure. Once a patient has developed a nonunion, it is important to have a frank discussion with him or her about healing outcomes following a surgical intervention. In cases of fractures that have developed nonunions but have not been primarily addressed via surgery, the soft tissue envelope is not a great concern. In revisional surgery, however, one needs to pay a great deal of attention to minimizing damage to the surrounding structures. The vasculature has already been damaged through the primary surgery and each surgical intervention decreases the body’s ability to regenerate normal vessels near the bone site. Newer bone grafting techniques and adjunctive treatments that employ blood derivatives are steadily gaining in popularity. However, these treatments have mostly been discussed in the realm of primary surgical procedures. In nonunions that require resection, the gold standard for grafting is still autogenous donation. Numerous techniques have been perfected that negate the need for a second surgeon to harvest the graft unless an unusually large amount of bone loss has occurred. Case Study: When Radiographs Reveal A Nonunion Of A Calcaneal Fracture And Subtalar Arthrosis A 38-year-old male sustained an intraarticular calcaneal fracture after falling from a height of approximately 10 feet. He was a traveling carnival worker and was initially treated at a local emergency room with compression and orders for non-weightbearing. He did not seek follow-up care. Approximately six months later, the patient presented to our office with a persistent antalgic gait and chronic swelling. Radiographs revealed a nonunion of the calcaneal fracture with subtalar arthrosis. Non-compliance was a large contributing factor but failure of the fracture site to heal, even in a malposition, can also be attributed to the patient’s 20-year history of smoking. After discussing the surgical options with the patient, we determined that a triple arthrodesis with resection and grafting of the non-union was in his best interest. We employed Synthes locking plates on the arthrodesis and nonunion sites. Typically, one would repair a nonunion with autograft as opposed to allograft due to the high risk of failure. However, since this was not a joint site and the nonunion involved the calcaneus, which is highly vascular, we used allogenic bone. Specifically, we utilized cadaveric cancellous bone to fill the gap following resection of the nonunion. After the procedure, the patient was hospitalized for one week for pain control and dressing changes. We treated the patient with external bone stimulation and emphasized strict non-weightbearing for eight weeks followed by protective weightbearing for an additional four weeks. Other than delayed soft tissue healing about the lateral incision, the patient healed without complications. Case Study: A Smoker Who Presents With A Significant Varus Deformity And A Drifting Foot The patient is a 58-year-old smoker who had a history of polio at a young age. He had undergone seven surgical attempts at tendon transfers over the course of his life to reduce the significant varus deformity of his right foot and ankle. On the eighth attempt, the patient underwent a triple arthrodesis with an anterior tibial transfer. The most recent surgery was performed approximately 30 years prior to when I initially examined him. He presented with a complaint of chronic pain and instability that had failed to respond to bracing. Radiographs revealed a successful arthrodesis of the entire rearfoot complex and advanced arthrosis of the ankle. He still had a significant varus deformity secondary to neuromuscular imbalance. The patient initially underwent a primary ankle arthrodesis with external fixation and healed uneventfully. However, approximately two years later, he presented to our office stating that, three months earlier, he began noticing the foot drifting “in the opposite direction” compared to where it had been before surgery. The clinical examination revealed a lateral shift of the foot in relation to the tibia. It was obviously secondary to a nonunion of the arthrodesis site. We performed a revisional arthrodesis that involved resection of the avascular bone from the superior talus and inferior tibia. The medial malleolus was removed entirely and used as an autogenous graft. We achieved fixation with compression staples and a unilateral external fixator. Subsequently, we placed an implantable bone stimulator within the arthrodesis site. The patient remained an inpatient for pain management for one week postoperatively. Upon his release from the hospital, the patient was enrolled in a smoking cessation program. He remained non-weightbearing for eight weeks and then proceeded to partial weightbearing for four weeks. At this point, we removed the fixator and the patient proceed to weightbearing in a removable cast boot for four weeks. He healed uneventfully. Even though the medial malleolus was used as a graft, this would have been an excellent case for resection of the nonunion and bone transport with compression using external fixation. This would have addressed limb length discrepancy, which would naturally occur with this much bone removal. In Conclusion Nonunions are a challenge to the podiatric surgeon. However, the aggressive use of pre- and postoperative measures can significantly reduce this challenge. Educating the patient and addressing complications early are two of the main goals in successful management of nonunions. Dr. Burks is a Fellow of the American College of Foot and Ankle Surgeons and is board certified in foot and ankle surgery. Dr. Burks practices in Little Rock, Ark. For related articles, see “How To Evaluate And Treat Calcaneal Fractures” in the November 2005 issue, “Early Weightbearing After Lapidus: Is It Possible?” in the August 2004 issue or check out the archives at www.podiatrytoday.com.