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Robert Frykberg,
DPM, MPH PRESENT Editor, Diabetic Limb Salvage |
The Diabetic Charcot Foot
To Operate or not to Operate?
I've just returned from my favorite meeting of the year, that of the Diabetic Foot Study Group of the EASD (European Association for the Study of Diabetes). One of the common themes of this meeting (again) was the Charcot foot. We've discussed this important complication of diabetes several times in the last few years, but I'd like to address a rather controversial topic in this month's issue- that of Charcot foot surgery. First, let's review (briefly) the underlying etiology of this condition as discussed in a Foot Notes from early 2011, entitledUnderstanding the Etiology of the Diabetic Charcot Foot:
"This rare complication of diabetes ultimately has peripheral neuropathy as its primary predisposing risk factor. In fact, neuropathy must be considered the sine qua non for the development of this very destructive bone and joint disorder. While Charcot first described his findings of the "arthropathies of locomotor ataxia” in patients with tabes dorsalis (syphilis), we now recognize diabetes to be the most common disease with which this entity is associated. More specifically, it is associated with patients who have long standing diabetic peripheral neuropathy. Despite this, we know that peripheral neuropathy resulting from anydisease can potentially predispose that extremity to the development of a "Charcot joint”. Aside from diabetes and tabes dorsalis, leprosy and alcoholism are two of the more common diseases having been associated with Charcot arthropathy of the lower extremities. In the upper extremity, syringomyelia might be the most notable potential disease associated with the condition. Nonetheless, neuropathy alone does not cause Charcot arthropathy. Trauma, either a minor occult injury, prior foot surgery, or a significant traumatic event such as an ankle fracture, is usually the precipitating event leading to the gradual breakdown of the architecture of the foot. Unfortunately, due to the insensitivity present, a definite history of trauma (especially minor injury) cannot be determined in most cases. The diminished sensation of pain (or total insensitivity) allows the patient to continue walking on the injured foot, thus promoting further injury. In essence, a "vicious cycle” of initial injury followed by repetitive injury and further deterioration is created. As might be expected, this results in swelling, erythema, deformity, and acute inflammation in the initial stages of this arthropathy. In fact, it is the acute inflammation without commensurate degrees of pain that most often characterize the initial presentation of such patients. Classically painless, most current reports indicate that pain is usually present in the acute stage, but much less than would be expected for the degree of injury noted on radiographs”. It might be a nice refresher to go back and review that issue to review the current concepts underlying the etiology of Charcot foot deformities.
Understanding the pathophysiology is of utmost importance when approaching the treatment of this difficult condition. It is indeed a challenge! I am a proponent of conservative care first and foremost, since the majority of patients can likely be treated with rest, immobilization, and protected ambulation once the acute inflammation has settled. Of course, this is dependent upon the degree of deformity present upon initial diagnosis and after the inactive stage has been reached. If the chronic Charcot foot can effectively be managed non-operatively with protective footwear, this course of long term treatment should be followed with regular surveillance. Unfortunately, this neuropathic foot deformity is prone to ulceration even when wearing protective footwear. Recurrent ulcerations despite provision of pressure reducing footwear indicate that conservative care with footwear alone might prove to be difficult. In such cases, the clinician can also consider using protective bracing or custom prostheses such as the Charcot Restraint Orthotic Walker (CROW). [ Figure 1 ] These custom patellar bearing braces can also be used for very unstable deformities, such as those involving the ankle. Nonetheless, conservative measures in such situations all too frequently fail and surgical management needs to be considered. Even thirty years ago, surgery on the Charcot foot was considered to be a very risky endeavor and was widely frowned upon. It is still considered to be very risky. However, it has become much more common in clinical practice over the last 20 years or so. Make no mistake however; these patients are very complicated, the surgical corrections can be very complicated, and the complications of surgery are common. Postoperatively, Charcot patients (who are already metabolically ill) can be prone to infection, deep venous thromboses, wound dehiscence, amputation, cardiac events, strokes, and death. What's more, recovery times are usually prolonged, dependent upon the nature of the surgery.
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Figure 1: Charcot Restraint Orthotic Walker
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Despite the aforementioned complications, corrective or reconstructive surgery is most frequently of benefit to the appropriate surgical candidates (as previously mentioned). When deformities are corrected, these patients can resume the safe use of protective footwear and walk with more stability and freedom from recurrent ulceration than they otherwise might have been able to do had they not undergone surgery. Common procedures include simple removal of bony prominences (exostectomy), tendo- Achilles lengthening, and reconstructive procedures such as realignment arthrodeses of affected joints of the foot and ankle. [ Figure 2 ] Most commonly, a combination of internal and external fixation is used to maintain the correction as healing takes place. Of particular note, lengthy periods of offweighting are required during the postoperative period – even six months or longer. Once healed, these patients still will require protective footwear, since they are always at high risk for developing ulcerations despite the operative correction. Sometimes the surgery is unsuccessful in maintaining correction or achieving a solid union, but the foot is still in a better position to accept weight bearing.
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Figure 2: External circular frame used to correct midfoot Charcot deformity by realignment arthrodesis.
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Unfortunately, there is not a lot of prospective, high quality evidence to support the role for surgery in the Charcot foot. We do not know which patients or specific regions of the foot are best treated with surgery rather than conservative care. There have been no comparative trials to guide us in this regard. Furthermore, we do not even know if operated patients fare better over the long term than non-operatively treated patients. One recent study attested to the lack of good evidence and reported that the majority of such operated patients in our literature come from only four centers. Most studies are single center and retrospective in nature. With that being recognized, however, there are a multitude of case series and case reports of successful operative outcomes in these patients. In the absence of high quality evidence, therefore, we must proceed with caution- but optimism in the hopes that we can make a difference in the long term outcomes for these patients. Patient selection is always key in this regard. We must always pay attention to the basics of care (offloading, immobilization, rest, etc.), but when these fail to prevent ulceration or stability, the consensus of opinion is that surgical intervention should at least be considered and be performed by those surgeons with expertise in managing this very difficult condition.
References are provided below to explain (and support) the concepts discussed above. We will also revisit this somewhat controversial topic in the future to explore this option further.
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We welcome your opinions, concerns, and suggestions. If you have an interesting case or a troubling circumstance that you would like to share with fellow PRESENT Diabetes members, please feel free to comment on eTalk.
Best regards,
Robert Frykberg, DPM, MPH
PRESENT Editor,
Diabetic Limb Salvage
REFERENCES
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