Hip Pain
In this article we’ll consider the various manifestations of hip pain and what could be at the root of some of these aches and pains. But first we’ll need an understanding of the anatomical structure of the hip itself.
Each hip bone is comprised of three smaller bones: the ilium, the ischium, and the pubis. At birth these three bones are joined together by cartilage. By the time we reach our mid-twenties, they fuse together through a process known as ossification. The two hip bones are joined together by the sacrum and coccyx to form the pelvis.
The sacrum is also formed by unfused bones, namely five vertebrae, which begin to ossify by our late teens. The tail end of the sacrum, or what’s known as the tailbone or coccyx, is formed by 3-5 boney segments. Together these two bones join the two hip bones into what’s known as the sacro-iliac joint (SI joint).
All the bones of the pelvic girdle are held together by strong fibrous ligaments. The weight of the upper body rests on top of the pelvis and is then transferred diagonally into the hip sockets and down the legs. Although the SI joints are limited in movement, the two hip bones are designed to rock forward and backward independently of one another as we walk. On occasion the SI joint can get locked in place, whether due to injury or constant tension in the hip muscles, and prevent the natural movement to transfer up the spine. Since each hip bone can move independently of one another, it’s also possible for them to get locked into an anterior or posterior tilt, creating a leg length discrepancy.
The hip is capable of six different movements: flexion, extension, abduction,adduction, medial and lateral rotation. The hip joint is considered a ball and socket joint, which affords it the unique ability to move on so many planes. As mentioned in a previous post, there is what’s considered a normal degree of movement or “range of motion” for each plane.
Flexion: 80-90 deg w/extended knee — 110-120 deg w/flexed knee
Extension: 10-15 deg
Abduction: 30-50 deg
Adduction: 30 deg
M. Rotation: 30-40 deg
L. Rotation: 40-60 deg
Each movement in turn is performed by a series of muscles. Some of these muscles are known as primary movers, while others are known as synergists – that is, they assist the primary movers in their function. Flexion is done with a total of 10 muscles, extension – 6 muscles, abduction – 5 muscles, adduction – 6 muscles, medial rotation – 6 muscles, and lateral rotation – 8 muscles. When the hip is functionally optimally, all these muscles and joints work free of pain and with a normal range of motion. But as we’ll see, age, injury, and normal wear and tear are just some of the factors which can contribute to hip pain.
Hip Injuries and Conditions
Of the many muscles that cover the hip and allow it to function, there are a number of them that also cross over into the low back and down into the legs — any of which can become strained. There are also a number of ligaments and bursa (fluid fill sacs) in and around the hip which can become lax or inflamed due to overuse. The exact placement of the pain therefore becomes an important factor in determining what the source of the pain could be. Here are several of the most common forms of hip pain. (For nerve pain that affects the hip, see a previous post on sciatica).
Anterior/Medial (Front & Inside) Hip Pain:
Adductor Strain (aka: Groin or Rider’s Strain)
The adductors are a group of five individual muscles located on the inner part of the thigh that move the hip and leg towards the midline of the body. Pain associated with an adductor strain will present itself as a sharp, stabbing pain in the groin area. An injury to any of the muscles that originate on the pubis is the most common cause. Irritation of these muscles can also lead to inflammation. On occasion, bruising and swelling may occur several days after the injury. If not addressed properly, an injury to any of these muscles can lead to chronic pain. Abduction of the hip (swinging the leg away from the midline of the body), will stretch adductors and elicit the pain.
Quadricep Strain (aka: Rectus Femoris Strain)
The quadriceps muscles are found along the front, inner and outer parts of the upper leg. They are considered primary movers in knee extension. The quadriceps get their name from the fact that there are four individual heads. Only one of these heads however crosses both the knee joint and the hip joint – that muscle is called rectus femoris. It is the most central head of the quadriceps and by far the most commonly injured. This is due in part to the fact that it contracts both concentrically and eccentrically, and is the only head of the quadriceps which assists in hip flexion. As a result it can become easily fatigued and overused in sports involving kicking, cutting (side to side), and start & stop movements.
Pain is usually felt in the front and inner parts of the thigh where the muscle originates on the hip. With first degree or mild strains, your gait will not be affected – but it will be with more severe strains. Stretching the muscle by flexing the knee and extending the hip will elicit the pain, as will contraction of the muscle through hip flexion and knee extension.
Iliopsoas Strain
The iliopsoas is considered a strong hip flexor and primary mover in hip flexion. In reality, the iliopsoas muscle is actually two muscles — the psoas and the iliacus. The psoas originates along the lumbar spine and the iliacus along the front of the pelvic bone. They blend together to cross the hip joint and attach on the femur. Pain from an iliopsoas strain will be felt in the groin area – that is, the front and inner part of the thigh. In severe strains it may be difficult to stand up straight without causing pain. The iliopsoas is most commonly injured when the hip is forced into extension from a maximally flexed position.
Since the muscle attaches itself along the inner part of the femur, abducting the hip (swinging the leg out), extending the hip or internally rotating the leg will stretch the muscle and cause pain. Contracting the muscle through hip flexion will also be painful.
* Pain associated with any pathology of the hip joint itself is typically felt in the groin and antero-medial aspect of the thigh.
Posterior (Back) Hip Pain:
Hamstring Strain
The hamstrings consist of 4 individual heads located along the back of the thigh. Three of these heads cross both the hip and knee joints – two along the medial aspect of the thigh and one along the lateral aspect of the thigh. The 4th head is found along the lateral aspect of the thigh but does not cross the hip joint. The lateral head that does cross both joints is known as biceps femoris. It is this part of the hamstrings that’s most commonly injured.
Since three of the hamstrings including the biceps femoris originate on the ischial tuberocities (aka: your sitz bones), the pain associated with a hamstring strain is usually felt at this insertion point. The hamstrings can also be injured at their insertion points on the inner and outer aspects of the knee, but more often than not the pain will start at the sitz bones and radiate down the leg. If not treated properly, a hamstring injury can become a chronic problem.
The hamstrings are primarily involved in hip extension and knee flexion. They’re also involved in medial and lateral rotation of the leg. They’re most commonly injured in sports involving running, kicking, or any activity that suddenly over stretches them. The pain can be exacerbated by sitting, fast running or stretching.
Ischial Bursitis
Located between the sitz bone and the gluteus maximus is a small fluid filled sac known as a bursa. Bursa are found around the joints of the body. They provide cushioning and reduce the amount of friction muscles and tendons exert as they glide over the boney prominences of a joint. The ischio-gluteal bursa as it’s known can become irritated from prolonged bouts of sitting – although this is not usually the cause of inflammation. This inflammation can on occasion irritate the sciatic nerve and cause pain down the leg.
The pain resulting from ischial bursitis however is pin point and con-scribed to the area around the sitz bones. It can come on suddenly and make sitting or sleeping on the affected side rather painful. Coughing, sneezing or any bearing down can exert pressure on the bursa and cause pain. People with ischial bursitis will often shorten their stride as they walk or lean away from the affected side while sitting to help alleviate the pain.
Lateral (Side) Hip Pain:
Abductor Strain
The most commonly strained muscle in an abductor strain is the gluteus mediusmuscle. Located on the outside of the hip, the gluteus medius is partly buried beneath its bigger brother — gluteus maximus. The other half of the muscle is superficial and easily felt along the pelvic bone toward the lateral and anterior aspect of the hip. The gluteus medius does a little of everything. Its primary function is hip abduction (swinging the leg out), but segments of this muscle are also involved in flexion, extension, and medial and lateral rotation.
One of the most important functions of this muscle is stabilization of the hip. As the weight of the body shifts onto each leg as we walk or run, the gluteus medius must contract and exert enough force equal to twice our body weight! If this key muscle becomes weakened or strained from overuse, it will loose its ability to stabilize the hip and allow it to buckle while weight bearing.
There are several factors which could strain this muscle. Being overweight can exert more pressure over this muscle than it can bear. A cross-over gait or running on banked surfaces can also overload this muscle. Over time the weakened side will force the opposite hip to drop and adaptively shorten, causing a functional shortened leg.
Pain from an abductor strain is felt along the lateral, outside aspect of the thigh. The pain can be particularly acute while running and often mimics the pain of trochanteric bursitis. Stretching the abductors by swinging the leg inward will cause pain, as will contraction of the abductors (swinging the leg out).
Trochanteric Bursitis
An inflammation of the three bursa found around the hip socket is known as trochanteric bursitis. The bursa can become inflamed due to arthritis, obesity, or a strain of any of the hip or lower back muscles. This in turn can lead to faulty postures and abnormal gaits. Shortening of these strained muscles can contribute to chronic tension along the hip socket and eventually irritate the bursa.
The pain from trochanteric bursitis can be a deep, dull pain or a sharp ache along the outside of the hip that extends down the lateral part of the leg. The pain is usually worse at night and can make it difficult to sleep on the affected side. A cross-over gait while running can lead to irritation of the bursa, as well as a leg length discrepancy or a pronated foot.
