Hip impingement is a fairly common problem, but that doesn’t mean it’s normal. Pinching, catching, popping, snapping… all words that may come to mind if you struggle with impingement. Part I of this blog takes a deep dive into what hip impingement is and what can be done to help manage it.
WHAT IS HIP IMPINGEMENT?
Femoroacetabular impingement (FAI), otherwise known as hip impingement, occurs when the femur (thigh bone) makes excessive contact with the acetabulum (pelvis) and results in pinching of the anterior structures of the hip [1]. There are a few different causes of FAI:
Structural FAI
Some people are naturally born with a hip joint structure that makes them more prone to developing symptoms. There are 3 types of structural problems:
Cam impingement- extra bone growth on the femoral heal
Pincher impingement- extra bone growth on the acetabulum
Combination of cam and pincer
In all of these scenarios, the extra growth causes the bones to excessively come in contact with one another during movement, which can result in pinching of soft tissues and discomfort.
Functional FAI
Functional FAI is the result of muscle imbalances and altered movement patterns. When the hip moves, the joint must stay centered. So, the ball must stay in the middle of the socket throughout the entire range of motion. Otherwise, we get excessive stress on one part of the joint. In the case of hip impingement, the head of the femur tends to shift forward, putting more stress on the front part of the joint [2].
Having good muscle strength and stability is what helps maintain proper alignment and prevents impingement. There is evidence that those with hip impingement have greater hip muscle weakness and altered movement patterns compared to other asymptomatic individuals [3].
There are also other diagnoses that can coincide with FAI, such as labral tears, tendinitis, or early onset osteoarthritis. Early treatment and prevention is key to lowering your chances of developing any of these secondary problems.
ANATOMY OF THE HIP JOINT
The hip is a ball and socket joint, made up of the head of the femur (ball) and the acetabulum on the pelvis (socket). There are numerous ligaments and muscles that help to stabilize and support the joint during movement. In the case of FAI, we tend to see muscle activation change as a protective strategy to avoid pain and discomfort. Here’s a few key muscles that play a role in hip impingement:
Tensor Fascia Latae (TFL)- This muscle on the front, lateral part of your hip and helps with
lifting, or flexing, the hip. Remember how I mentioned the hip joint must stay well-centered during movement? When overactive, this muscle is responsible for causing excessive forward glide of the femoral head and impingement [2].
Iliopsoas (hip flexor)- This one always gets a bad rap. “It’s so tight.” “I feel like I need to stretch all the time.” Sound familiar? Well, “tight” is not usually not the problem. WEAK is the problem. The hip flexor is responsible for flexing, or lifting, the leg. However, when it is weak or under trained, the TFL overpowers it. The result? more forward glide, and more pinching. Strengthening the hip flexor will help keep the joint more centered and you will be shocked at how fast that “tight” feeling subsides without needing to stretch.
Hip rotators- These are a group of small muscles on the back side of the joint that rotate the hip, as well as provide stability during movement. We tend to see altered strength, mobility and movement patterns in the hip rotators in patients with FAI.
SYMPTOMS OF HIP IMPINGEMENT
Pain in the front of the hip that may also radiate to the outer hip (also called the “C-sign” because the pattern of pain is in a C-shape)
Pinching, catching or popping in the hip that occurs with movement
Worse with hip flexion (i.e. lifting the leg, sitting, up & down stairs, squatting)
Limited mobility, most commonly with internal rotation and flexion
Hip muscle weakness
STRUCTURE DOES NOT DICTATE FUNCTION
FAI is common in the general population, but not everyone has symptoms. Before you run out and get an MRI, know this: Research continues to show that a large majority of people with hip pathologies present on MRI scans are often completely symptom free.
Most recently, a study was published in the Journal of Clinical Radiology looking at the prevalence of labral tears in asymptomatic dancers and rugby players. Each participant in the study was completely free of symptoms at the time of the MRI. It was found that labral tears were present in 87% of hips, and cartilage loss was present in 54% of hips [5]. You can see that structure does not always dictate function, and often MRI’s to diagnose FAI are not necessary.
So why do only some people develop symptoms? It depends a lot on your activities. FAI is more problematic in activities that involve extreme ranges of motion, like dance or soccer. In dance, for instance, the hip is flexed repetatively, which is a motion that naturally causes the bones to come closer together. Combine that with altered movement mechanics, weakness or structural changes, and you end up with a much higher likelihood of developing symptoms.
TREATMENT FOR HIP IMPINGEMENT
Physical Therapy
To be honest, the research is still mixed on the best course of treatment. In my experience, conservative care (AKA Physical Therapy) should always be your first step. Physical therapy has positive outcomes when it comes to pain and symptom relief for FAI. Treatments may include hands on therapy, strengthening, mobility work and of course, lots of patient education [5]. In my own opinion, it is extremely important that you seek out a Physical Therapist who is experienced at treating FAI. Not all PT’s are created equal, and it can make or break your success in rehab.
The single most important thing to know about Physical Therapy for impingement is that there are no quick fixes. While FAI is very treatable, it usually takes a lot of time and consistency to see the benefits. Don’t let this frustrate you! It is completely normal, because remember, we are actually trying to change your movement patterns and strengthen muscle. It takes time, but is a much better alternative than surgery.
Surgery
The goal of surgery is to reshape the bone to reduce the amount of contact between the femur and pelvis during movement. Surgery may also address any labral tears that are present. Rates of FAI diagnosis have skyrocketed since the early 2000’s, which means so have the rates of surgery. There is still limited evidence that surgery improves long term outcomes for hip impingement patients, but we do know that younger age and less cartilage damage are the best predictors of a positive outcome [6].
In my own clinical experience, while there are some patients that benefit from surgery, there is still a large percent who continue to have pain and limitations after surgery.
Here’s why:
Surgery only corrects the structural component and in no way changes your movement patterns. This means that, for patients who opt to have surgery, the problem will not magically go away. Yes, the structure is no longer the problem, but you MUST STILL work to correct the muscle imbalances that contributed to the problem in the first place. Otherwise, the pain and limitations will most certainly return.
Whether you opt for surgery or not, we know that Physical Therapy is a must!!
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REFERENCES:
1. Griffin DR, Dickenson EJ, O'Donnell J, et al. The Warwick Agreement on femoroacetabular impingement syndrome (FAI syndrome): an international consensus statement. British Journal of Sports Medicine 2016;50:1169-1176.
2. Sahrmann S. Diagnosis and treatment of movement impairment syndromes. Elsevier Health Sciences. 2002
3. Casartelli, N. C., et al. "Hip muscle weakness in patients with symptomatic femoroacetabular impingement." Osteoarthritis and cartilage 19.7 (2011): 816-821.
4. Blankenstein, T., et al. "MRI hip findings in asymptomatic professional rugby players, ballet dancers, and age-matched controls." Clinical Radiology 75.2 (2020): 116-122.
5. Mallets, Emma, et al. "Short-term outcomes of conservative treatment for femoroacetabular impingement: a systematic review and meta-analysis." International journal of sports physical therapy 14.4 (2019): 514.
6. Lund, Bent, et al. "Danish Hip Arthroscopy Registry (DHAR): the outcome of patients with femoroacetabular impingement (FAI)." Journal of hip preservation surgery 4.2 (2017): 170-177.