Complex regional pain syndrome after foot surgery: early signs

Pain is expected after foot surgery. But there is a difference between the pain you were told to expect and pain that grows instead of fading, reaches beyond the operated area, and brings skin changes along with it. That pattern can be a sign of complex regional pain syndrome, and catching it early matters.

What CRPS is

CRPS is a neuropathic pain disorder in which persistent pain is disproportionate to the severity of the tissue injury and continues beyond the usual expected period of healing. The pain is accompanied by sensory, motor and autonomic abnormalities: allodynia (pain from light touch), hyperalgesia (exaggerated pain), sweating and blood-flow abnormalities, and trophic changes in the skin. It often develops after trauma, a fracture or surgery. The pain is regional, which means it doesn’t follow a specific nerve’s distribution, and it typically involves the distal part of the limb.^[1]

There are two types. Type 1 arises without a known nerve injury, and type 2 follows a known nerve injury. Their clinical features are indistinguishable.^[1] A widely used set of diagnostic criteria, called the Budapest criteria, was proposed in 2010.^[1]

Early signs to watch for

Tell your surgical team if, in the operated foot or leg, you notice:

• pain that is much greater than you expected, is getting worse instead of settling, or is out of proportion to how the wound looks
• touch, a sock or a bedsheet that hurts when it shouldn’t
• changes in skin color or temperature, compared with the other foot
• swelling that doesn’t follow the usual pattern
• changes in sweating, or in hair and nail growth
• stiffness or weakness in the toes, ankle or foot

Pain with changes in skin color or temperature, swelling or sweating can be a sign of CRPS, which benefits from early recognition and treatment.^[3,1]

How common is it after foot and ankle surgery?

A retrospective study of 390 people who had elective foot and ankle surgery found that 17 (4.36%) met the International Association for the Study of Pain criteria for CRPS. Most were women (82%), about half had had forefoot surgery, and some developed it after more than one operation. Three had documented nerve damage during the operation and developed CRPS type 2. The authors recommended that middle-aged women and people with a history of anxiety or depression be counseled about the risk when they consent to elective foot surgery.^[2] These are associations found in one study, not predictions for any individual.

Can it be prevented?

Research on prevention is mixed. In a randomized study of 329 people having foot or ankle surgery, taking 1 g of vitamin C a day for 40 days after surgery was linked to a lower risk of CRPS (odds ratio 0.19). The same study found that alcoholism and cast immobilization were associated with higher risk.^[4] A later systematic review and meta-analysis of eight studies found that the pooled effect of vitamin C was not statistically significant, and it noted signs of publication bias.^[5] Whether to take any supplement after surgery is a question for your surgeon, not something to decide on your own.

How CRPS is treated

There is no single proven treatment. The current practice guidelines note that most of the research is of low to medium quality, with small numbers of people, so treatment is tailored to each patient and usually involves several approaches.^[6] Your surgeon, pain specialist and therapist may all be involved. CRPS benefits from early, coordinated care.^[1]

Where a nerve evaluation fits in

Not every burning pain after foot surgery is CRPS. A nerve can be stretched, trapped in scar tissue or cut, and a painful neuroma may form at the injured end. Those problems are localized to one nerve’s area and have their own treatments, and sometimes a nerve injury and CRPS are both present. A careful evaluation aims to tell them apart, and to recognize when a nerve problem might be contributing. See nerve pain after ankle surgery, nerve pain after surgery or injury and painful neuroma. We communicate with your original surgeon and other clinicians where that helps your care.

When to see a specialist

Consider an evaluation if burning, electric or shooting pain after an injury or operation lasts more than a few weeks, is getting worse, or keeps you from wearing shoes or sleeping.