Complex Regional Pain Syndrome or CRPS is a somewhat poorly understood but accepted pain syndrome marked by injury or surgery to a limb and the development of a constellation of symptoms (Laplant 2014).


Early CRPS indicators

  • Pain out of proportion to insult
  • Colour changes in limb
  • Temperature changes in limb
  • Non-typical swelling

When we are injured we experience what is known as a “fight or flight response” mediated by this sympathetic nervous system, and which is normally helpful in dealing with the injury, but in CRPS the reflex goes somehow wrong.

In CRPS a “cycle” develops in which your body sends signals to your brain that the injury is still occurring, despite being in a normal healing time frame.

And your body responds in kind with pain and swelling and all of the other symptoms of 'fight or flight' like vasodilation or vasoconstriction (opening or closing of the blood vessels) that are responsible for the color changes of the skin in CRPS. It is like a computer that needs to be “rebooted”. This altered feedback loop is responsible for many of the symptoms of CRPS.


Types of CRPS

Technically there are two types of CRPS:

  • Type I - CRPS Type I does not include any specific nerve damage and has a higher prevalence in the public
  • Type II - CRPS Type II involves documented nerve damage (such as a necrotic nerve after suffering oxygen deprivation due to 'compartment syndrome' for example) and is less common. There is also a psychological or 'psychophysiological' component to CRPS, as there is a correlation between CRPS and anxiety and depression mood disorders of between 24-65%. However, chronic pain sufferers of other conditions have similar statistics (Fishman et al, 2012) so the relationship is not necessarily causal. There is however an undisputed relationship between our central nervous system and our autonomic nervous system that causes this vicious cycle of pain. CRPS is multifactorial and involves multiple symptoms and is still poorly understood, despite its acceptance (a helpful diagram may be found at As Wilson, (2007) described, “peripheral mechanisms lead to central hyperexcitability and sensitization seen in CRPS”
Michelle Boucher
As a patient, it is difficult to know what level of pain is to be expected and what level is 'disproportionate'.
As a general guide, the pain level should be improving as the weeks pass, and if the pain is increasing in intensity, especially if accompanied by any of the neurologic signs we have discussed, this is a concern that must be brought to the attention of the team. Communication within the team, your physician, surgeon and physiotherapist are imperative. Appropriate follow-up must be had with the surgeon as well as a consult with a pain management physician and continued physiotherapy as tolerated. Patients must be their own advocates. This is not a time to become shy. Voice your concerns. Be insistent.
CRPS is a debilitating, life-changing disease that can be chronic and last a lifetime. Unfortunately, CRPS is rarely diagnosed before three months postoperatively. Early recognition and treatment with early sympathetic ganglion blocks, bisphosphonates and even Vitamin C have been used with mixed results, as well as proper pain management to enable continued physiotherapy.

But, what can be done? Adequate pain relief to permit continued physiotherapy is imperative, most all agree. Not to be over-estimated, a diligent search by your surgeon for any other explanation of your symptoms that may be attributable to another cause. The mainstay of treatment has been continued physiotherapy, adequate pain management with opiate pain medication, NSAIDS (non-steroidal anti-inflammatories) as well as topical Capsaicin and Lidocaine patches, gabapentin and even anti-depressant medications and psychotherapy.​

The management of continued pain after a knee surgery is not well established. Some surgeons, such as Toms, 2009 who studied TKA patients used a guidepost of increasing pain at the three-month mark, especially causing stiffness, to consider CRPS. He comments that revision procedures are rarely helpful in the treatment of CRPS. Many argue that revision surgery after a diagnosis of CRPS may only worsen the situation. There are situations when revision surgery is deemed necessary. Some teams perform revision surgery in which an anesthesiologist provides a nerve block pre-operatively, at the Lumbar-Sacral region (L5-S1). Before surgery, the nerves are “turned off” thereby allowing the body a form of 'amnesia for the insult', as it were, providing a greater chance that the body will fail to 'remember' the insult of revision surgery. These cases are largely anecdotal, and must be well timed and coordinated by a specialized team with the expertise to attempt these cases (Tubic, 2015).​​

CRPS is a diagnosis of exclusion, meaning that all other potential causes of the symptoms must be excluded. An informed and astute patient and physician and physiotherapist are imperative to making the correct diagnosis. Any disease, such as a postoperative infection that may be masquerading as CRPS, and is readily treatable, must be afforded the opportunity for appropriate treatment. CRPS is a clinical diagnosis, and there are no definitive tests that will declare the diagnosis. This too often this leads to a delay in diagnosis. As mentioned, CRPS is delineated to types I and II - however in this following discussion we will assume for simplicity purposes that we are discussing Type I.

A seasoned physiotherapist may be the first to discern that CRPS is developing as the patient will be limited in their ability to progress through the typical physiotherapy regimen due to pain.​

CRPS is most common after hand surgery and in the upper extremity (Sebastin, 2011) however each year a percentage of knee patients will develop the disease postoperatively. Among all CRPS patients, randomized studies are few, especially among knee patients. However, reported CRPS after Total Knee Arthroplasty (TKA) is reported to be 21% at one year (Toms, 2009) with decreasing percentages at years 2 and three postoperatively. Among ACL reconstruction patients, the numbers appear to be lower, in the range of 4% (Reuben, 2004) however some estimates range that up to 13 % of patients who undergo this procedure will develop CRPS.​

How to know if you are one of these unfortunate patients? As a patient, you may experience pain that appears disproportionate to what 'was expected'. This, as you may realize, is very subjective. Who knows what to expect? This may present as pain that is worsening as you get further out into 'recovery', not improving. Is your pain threshold stifling your physical therapy? If you notice any change in color of the affected limb, such as the limb appearing pale or a mottled purple, or if there is any sweating you must report this immediately. Swelling that persists is also of concern. Stiffness or atrophy of the limb is a late finding.​


Jacquelyn Laplant, Robert Knobbler Early recognition of CRPS to facilitate effective early treatment. Neurology May 2014, poster

Sebastin, Sandeep Complex Regional Pain Syndrome. Indian Journal of Plastic Surgery 2011 May-Aug 44 (2) 29-307

Toms A.D., Madalia V, Haigh R. The management of patients with painful total knee replacement surgery. Journal of Bone and Joint Surgery (Br) 91-B 143-150.

Reuben, Scott. Preventing the development of Complex Regional Pain Syndrome after Surgery Anesthesiology 2004; 101: 1215-1224.

Fishman Scott, Ballantyne Jane et al. Bonica’s Pain Management. Wolters Kluver Health, 2012, pages 81-85.

Wilson, JG, MG Serpell. Complex Regional Pain Syndrome. Continuing Education of Anesthesia and Critical Care and Pain Management 2007 7 (2) pages 51-54.


Why 'sympathetic'?

Clinically, prior to 1994 the syndrome was termed RSD or Reflex Sympathetic Dystrophy, drawing attention to involvement of the 'sympathetic' part of the nervous system.The clinical symptomatology of CRPS involves severe pain, swelling, temperature changes, pallor and sweating, numbness and tingling or allodynia (pain associated with normally non-noxious or non-painful stimulation such as clothing or normal touch), as well as impaired movement and tissue wasting.
Our nervous system is divided into a central nervous system and a peripheral nervous system. The central part is comprised of the brain and spinal cord, while the peripheral nervous system is that part outside of the brain and spinal cord that helps the limbs and organs to communicate with the central nervous system. The peripheral nervous system is functionally split into two parts, the 'somatic' part that deals with bodily functions that are under conscious control and the 'autonomic' part that controls bodily functions outside of our conscious control - but which can be triggered by anxiety as well. The autonomic part is divided into two systems that work in a complementary fashion, and the 'sympathetic' nervous system is one of these two systems.​