Plantar fasciitis - differential diagnosis
As a clinician who treats heel pain, one of the things you really need to be careful about is the fact that not all heel pain is plantar fasciitis. I'll grant you the fact that the vast majority of plantar heel pain is indeed plantar fasciitis. But heel pain can be so many things. Let's talk a bit about the differential diagnosis for plantar fasciitis.
We talked a bit in a previous blog post about the onset and symptoms of plantar fasciitis. The symptoms are classic and rarely vary. Patients who suffer from plantar fasciitis are usually between the ages of 35-65 years of age and may be just a bit overweight. Patients describe plantar (bottom of the heel) pain with initial weight-bearing. After a few steps, the heel pain subsides and gets a bit better, sometimes even going away for a while. But sit again and try to stand and the plantar heel pain is right back. The pain is often described as stepping on broken glass. Getting out of bed in the morning is one of the worst times of the day. As the duration of plantar fasciitis increases most patients will find the symptoms also become bad in the afternoon and evening after standing for a period of time. This pain is a bit different. Patients describe this pain not as sharp but more dull, like being hit in the heel with a hammer.
Patients suffering from plantar fasciitis also described good days and bad days. In the prior blog post, I discussed why this would happen. I've described plantar fasciitis as an overuse syndrome. So if you overuse it on a Monday you can expect Tuesday morning is going to be a tough day getting out of bed. Rest on Tuesday and Wednesday is going to seem like a better day. That's just the nature of an overuse syndrome. As an overuse syndrome, that's the roller coaster of plantar fasciitis.
Plantar fasciitis - what else could it be?
So if the pain isn't plantar fasciitis, then what else could it be? What other plantar heel pain problems do we need to rule out? Fat pad atrophy is a common complaint, particularly in older patients. With fat pad atrophy you can actually palpate (feel) the plantar tubercles of the calcaneus (heel bone). The pain of fat pad atrophy isn't so focused on initial weight bearing but seems to become a bit worse on hard floors while barefoot. Cushion under the heel will help to cushion the heel bone. When that cushion is gone, there's no cushion to protect the calcaneus. Like plantar fasciitis, the pain of fat pad atrophy will respond to rest.
Baxter's nerve entrapment
Another problem that can cause plantar heel pain is a nerve entrapment called Baxter's nerve entrapment. Baxter's nerve is the first branch of the posterior tibial nerve as it triforcates (splits into three branches) at the level of the medial ankle. Baxter's nerve supplies sensation to the plantar heel. The symptoms of Baxter's nerve entrapment are a bit different than those of plantar fasciitis. Where plantar fasciitis causes heel pain with initial weight bearing, Baxter's nerve entrapment has no pain with initial weight-bearing. But with Baxter's nerve entrapment pain will increase with the duration of weight-bearing. Simply put, the longer you stand the more it hurts. Another symptom of Baxter's entrapment that differentiates it from plantar fasciitis is the fact that Baxter's nerve entrapment continues to hurt once you're off your feet. Plantar fasciitis, on the other hand, will respond very quickly to rest. Baxter's nerve entrapment may also cause numbness of the plantar heel.
Calcaneal stress fracture
Stress fractures of the calcaneus (heel bone) are another problem to be ruled out in the differential diagnoses of heel pain. Calcaneal stress fractures may be due to a traumatic injury like a fall from a height or an auto accident, but the more common onset of calcaneal fractures is due to the onset of a new activity. The onset of basketball season or the patient who decides to start a new running program are the more common examples of what may cause a calcaneal stress fracture. Calcaneal stress fractures often have pain with initial weight bearing but not necessarily focused on the plantar heel. Pain can be elicited by compressing the body of the heel (side to side pressure). Swelling may be present but is not always the case. Pain with calcaneal stress fractures doesn't respond to rest. Often x-rays will fail to show changes in the heel bone to indicate a stress fracture. An MRI is often needed to visualize bone edema (swelling) in the bone that defines the fracture.
There's a number of other less common problems that cause heel pain. Achilles tendonitis and Haglund's disease are posterior heel problems and difficult to confuse with the classic symptoms of plantar fasciitis (plantar heel pain). Heel pain in an adolescent patient is often Sever's disease. And again, it's rare to see cases of plantar fasciitis in teens.
Although x-rays are not regularly used in making the diagnosis of plantar fasciitis (remember, plantar fasciitis is a soft tissue problem), x-rays are indicated when there is a suspicion of stress fractures or bone tumors. Bone scans are able to define areas of inflammation but cannot specifically define a fracture from say arthritis or osteomyelitis (bone infection) of the heel. Bone scans are used to determine if there is indeed an inflammatory component to a problem. MRI is often used to be the tie-breaker when compared to a bone scan in that the MRI is able to be more specific in terms of fracture or swelling. CT scans are also often used in differentiating the diagnosis of heel pain when fracture of the heel is suspected.
Reiter's syndrome and rheumatoid arthritis
A complete review of the differential diagnosis of heel pain wouldn't be complete without mentioning types of heel pain that are arthritic in nature. Reiter's syndrome is an uncommon diagnosis in my practice. I have seen several cases of rheumatoid arthritis that initially presented with plantar heel pain.
So is it plantar fasciitis or something else? If the symptoms that you're experiencing don't seem to follow any of these typical patterns, it might be wise to have a conversation with your podiatrist or orthopedist regarding the differential diagnosis of heel pain.
Additional topics in this blog series include-
Plantar fasciitis | History
Plantar fasciitis | Causes and contributing factors
Plantar fasciitis | Conservative methods of care
Plantar fasciitis | Surgical treatment
Plantar fasciitis | Additional treatment methods
Plantar fasciitis | Surgical complications