Of the joints in the leg that are commonly injured in runners, hip pain often poses the most difficult diagnosis. There are a couple of reasons for this: First, there are simply too many possible causes of hip pain, and a second, less obvious reason, relates to the frequency of these injuries.
The bony anatomy of the hip is actually quite straightforward. The head of the femur ends in a ball that articulates with a pocket in the pelvic bone, the acetabulum. This forms the classic ball-in-socket joint. Yet, because of the extreme forces that this joint is subjected to, especially when running, and because of the very complicated supporting structures that help make it among one of the strongest and most stable joints in the body, many potential sources of hip pain are possible. Because the hip plays such an important role in weight bearing and locomotion, it is of the utmost importance to identify these injuries as early as possible, and treat them before they result in joint damage.
We’ll review the more commonly encountered causes of hip pain in runners: muscular strains and pulls in the groin, hamstring or piriformis, hip flexor tightness, bursitis, stress fractures and labral tears. Iliotibial band friction syndrome (ITBFS) may also cause hip pain, but has been widely covered, and therefore will not be discussed in this article.
Groin Pulls or Tears
A pulled groin is caused by a strain in the hip adductors, muscles that pull the legs together. These muscles attach to the thighbones at the level of the hip and run down the inside of the thigh, stabilizing the joint. When overstretched or overused, small tears can develop resulting in hip pain, swelling, and a dull ache in the groin area. Severe tears occur more suddenly and are associated with very sharp pain and bruising down the leg.
Unfortunately, many hip injuries can cause groin pain as well, so distinguishing a true groin pull from other possibilities may not always be that straightforward. Usually a focused history and physical exam suffice to confirm the diagnosis.
The treatment of a groin pull is similar for other pulled muscles. Rest, ice, compression and elevation can all help to alleviate symptoms. Anti-inflammatory medications or acetaminophen can be used to treat pain and once the injury has healed sufficiently, a gradual return to activity can then follow.
The hamstrings are made up of three distinct muscles that run down the back of the thigh, which then operate together as powerful knee flexors. Like all muscular injuries, hamstring injuries occur when fibers within the muscles tear. The severity of the injury is determined by the amount of damage and how completely the fibers are torn—the least severe form being a strain, while the most severe consists of a complete tear.
Hamstring injuries are almost always associated with pain in the back of the leg that gets worse with flexing the knee. However, if the injury is higher up in the muscle body, then the symptoms can be experienced in the hip itself.
The piriformis is a small muscle that runs from the sacrum to the outside of the hip. For a small muscle it can cause big problems when inflamed or overused. Because it runs over the sciatic nerve, the piriformis has a nasty habit of putting pressure on this nerve and causing exquisite pain in the glute and posterior hip area when it swells or spasms.
Aside from addressing any mechanical issues that might be exacerbating the problem the main way to treat piriformis syndrome is by stretching the muscle out as much as possible. To stretch the piriformis: lay on your back, bend your knees and cross your right leg over your left so your right ankle rests on your left knee in a figure four position. Bring your left leg toward your chest by bending at the hip. Reach through and grab your left thigh to help pull everything toward your chest.
The iliopsoas muscle is a powerful hip flexor that runs across the top of the hip joint and works to pull the knee up and off the ground when it contracts. Movement of the tendon is facilitated by the iliopsoas bursa. If the tendon or the bursa becomes inflamed, flexion may become very painful and the pain is felt in front of the hip with an associated snapping or clicking sensation during movement. Iliopsoas syndrome often arises as a result of increasing volume or intensity too quickly, and hence this problem may be easily avoided. Once it has set in though, the only effective treatment is rest with liberal use of anti-inflammatory medications.
Bursae are fluid-filled sacs that assist in lubricating the movement of structures around joints. The hip bursa allows for the smooth movements of various tendons over each other as the hip ranges in different directions. In some instances this sac can become inflamed after repetitive micro-trauma common in long-distance running. The inflammation can be very painful with symptoms predominantly over the outer aspect of the hip radiating down into the thigh.
Once inflamed, the treatment for hip bursitis is similar to many of the other injuries described here: rest, the application of ice and the use of anti-inflammatory medications. Although it is rare, in some cases the bursitis may become severe or chronic and require surgery.
Although much more common in the foot and lower leg, stress fractures of the hip may also occur. Stress fractures result from a combination of overuse in the setting of muscle fatigue, and in some cases, predisposed anatomical issues. Under normal circumstances the muscles and tendons absorb the vast majority of the forces transmitted during repeated ground striking in running. However, with progressive fatigue, more and more of the force is transmitted to the underlying bone, and with time the bone may fracture.
Unlike a traumatic injury, in which there is a sudden tremendous force applied that results in an obvious disruption of the bone, stress fractures are insidious and take time to manifest symptoms. Stress fractures of the hip will cause a dull ache either felt in the groin or lower back, and this can delay the diagnosis allowing more time for the fracture to worsen. Once suspected, confirming the diagnosis can also be difficult as the bone may appear normal on plain X-rays. Only more advanced imaging will show the problem definitively.
Once diagnosed, a complete cessation of weight bearing exercise is mandated. This is critical in order to prevent the stress fracture from progressing to a much more serious and complete fracture. The duration of recovery will depend on the severity of the injury and, in rare cases, surgical intervention may be required.
Hip Pain Due to Labral Tear
The labrum of the hip is a cartilage ring that forms a kind of lubricating O-ring around the ball of the femur holding it in place in the acetabulum. In some people, bony abnormalities either of the neck of the femur or of the lip of the acetabulum can cause the labrum to become repetitively impinged with normal ranging of the hip joint. Over time, this impingement causes the labrum to fray and eventually tear.
Until recently, the long-term importance of labral tears wasn’t completely appreciated. Now, these tears are seen as a potential contributor to the early development of arthritis of the hip.
Because the labrum is made of cartilage and therefore completely insensate, the symptoms of a labral tear arise only long after the damage has been done. Patients with this problem frequently complain of pain in the groin that gets worse when crossing the affected leg over the other. Hence, the diagnosis is difficult to confirm and requires an MRI with contrast injected into the joint. Once confirmed, the only treatment options for symptomatic patients are the complete cessation of weight bearing activities or surgery. It is important to note that not all patients with labral tears require surgical repair. This should be discussed with an orthopedic surgeon familiar with the diagnosis and the procedure to address it.
The hip joint is less prone to injury than the lower leg but can still be afflicted by a number of issues both big and small. Quickly arriving at the correct diagnosis is an important part of getting effective treatment and returning to activity. Knowing the common causes of hip and groin pain is also an important part of that equation. See your physician whenever you have vague, non-specific pains that are difficult to ascribe to a specific area. This can often end up being something more important than you might initially think and catching it early is key.
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About the Author: Jeffrey Sankoff, MD is a three time Ironman and 70.3 World Championship qualifier. He is an Emergency Physician at Denver Health Medical Center in Denver.