Hip Impingement and Capsular Laxity

Hip impingement has been gaining a lot of attention lately. It can be a difficult diagnosis to manage as a physical therapist, depending on severity, and can be incredibly frustrating for the patient. As more evidence comes in, we are getting a clearer picture of what exactly is the cause, and it certainly looks multifactorial. One suggested mechanism is laxity of the anterior part of the hip capsule.

So first, let’s understand what a capsule is. All joints have capsules around them, and they are often likened to a leathery sack. They are a blend of ligaments, connective tissue, and tendons; so they are not a unique structure. They provide stability for the joint. Depending on the position of the joint, certain parts of the capsule are stressed. With rotational movements of the joint, the anterior capsule is stressed and becomes taught. The biggest ligament in the body is the iliofemoral ligament, or Y-ligament and is in the front of the hip. It has a major role in stability. In standing, it keeps the femoral head pressed into the acetabulum. It also resists hip external rotation. Activities like gymnastics and ballet place a lot of external rotational strain on this ligament, especially in positions like the splits or turnout in ballet. Ligaments are not contractile like a muscle or tendon. Once they are stretched, they don’t go back to their original shape. They become lax. 

Stability in the hip is created by several factors. There is a negative pressure inside the capsule that adds a layer of stability. In ball and sockets joints, the socket is lined with a fibrocartilage called the labrum. It deepens the socket and adds more stability. Also the muscles, tendons, and ligaments add stability. Labral tears are highly associated with hip impingement. Interestingly, the majority of labral tears in North American are in the anterosuperior part of the labrum and is associated with twisting/pivoting motions. In Asian populations, the majority of tears are posterior and are associated with hyperflexion from squatting motions (Mason, 2001). So it just may be a matter of repetition that creates laxity and leads to tearing. 


So if we have a situation where we’ve created laxity in a ligament/capsule, and have a deficient labrum from tears or fraying, we have two factors that can add up to an instability that worsen each other. It’s like the wheels coming off of a bus. On top of that, there is such a focus on stretching in ballet and gymnastics which probably make a bad situation worse. 

Additionally, there is what I call a “connective tissue profile”. This simply means we are all built different and there is a spectrum of elasticity to our connective tissues on an individual level. There are certainly disorders like Ehlers Danlos syndrome which is a more severe laxity, but it doesn’t have to be a syndrome for you to have more laxity than the next person. Hormones can change a ligaments integrity as well and is why there is a lot of back pain with pregnancy. Here is the other confounding factor; choice in sport. Stronger people tend to lift weights, and looser people tend to go into yoga. What I’m saying is that someone who has natural flexibility will excel in gymnastics and be drawn to that sport. 

So what do we do about all of this? First, assess how lax your hip is compared to the asymptomatic one. You can do it like this:

Then aim to stabilize the joint. Remember that muscles also create stability in the joint. So you can overcompensate in a sense by strengthening the muscles surrounding the joint. I would suggest starting with the deepest ones. There is a group of muscles that are analogous to the rotator cuff of the shoulder. They do hip internal rotation and external rotation. There are 13 of them: 

External rotators:

  • Piriformis

  • Gemellus Superior

  • Gemellus Inferior

  • Obturator Internus

  • Obturator Externus

  • Quadratus Femoris

Internal rotators:

  • Tensor fascia latae

  • Gluteus minimus

  • Gluteus medius

  • Adductor longus

  • Adductor brevis

  • Adductor magnus

  • Pectineus 

It can get confusing because some of the muscles change their function based on the amount of hip flexion/extension. So the easiest thing to do is hip rotation (internal and external) in multiple planes to create maximal stability.

Here is a drill I like to do for this: 

References:

Acetabular labral tears in the athlete - researchgate. (n.d.). Retrieved February 8, 2021, from https://www.researchgate.net/publication/11676689_Acetabular_labral_tears_in_the_athlete

Martin RL;Enseki KR;Draovitch P;Trapuzzano T;Philippon MJ;. (n.d.). Acetabular labral tears of the hip: Examination and diagnostic challenges. Retrieved February 08, 2021, from https://pubmed.ncbi.nlm.nih.gov/16881467/





Christopher EllisComment