The hip is the least susceptible joint to become injured, simply because of its size. The round head of the thighbone, the femur, fits snugly into the acetabulum, a shallow, rounded cavity on the outer wall of the pelvis. Hip injuries are uncommon in sports because the hip joint is exceptionally stable requiring considerable force to cause a dislocation or fracture. More vulnerable, however, is the groin, a web of ligaments and muscles lying between the lower part of the abdominal wall and the upper thigh. Strains are most often the cause of pain in the hip and groin resulting from high intensity sports, though the elderly often suffer from hip fractures due to osteoporosis. Symptoms and causes are generally the same for both the left and right side of the hip and groin.
Hip Fracture
In younger individuals, hip fractures can occur as a result of falling while cycling or skiing fracturing the neck of the femur. Though rare, these injuries cause intense hip and groin pain as well as referred pain in the back. More common in older individuals, hip fractures often occur due to osteoporosis. According to the American Academy of Orthopaedic Surgeons, most fractures of the hip occur in post-menopausal women. Long-distance running can also cause stress fractures of the hip.
Bursitis
Bursitis will cause pain in the outer part of the hip resulting in inflammation of a fluid-filled sac called a bursa that lies under the tendons running across the hip. According to MayoClinic.com, hip bursitis often occurs from frequent, repetitive movement such as running and bicycling. A direct blow to the hip or friction caused by an unusual style of running can also cause bursitis.
Buttock Strain and Hip Sprain
Pain on the outside of the hip is often the result of a strain of the gluteal, or buttock, muscle at the point where it attaches to the upper end of the thighbone. This injury most commonly occurs during long-distance running. A hip sprain results from a twisting injury that damages the ligaments or causes inflammation of the capsule that encloses the joint. Moving the hip becomes painful and stiff. One or the other of these injuries can cause referred pain making a definitive diagnosis difficult.
Legg-Calve-Perthes Disease
This disease occurs most often and almost exclusively in boys 4- to 10-years-old. Little is actually known about the disease, however. According to the University of Maryland Medical Center, a diminished blood supply causes Legg-Calve-Perthes disease, affecting the ball of the thighbone causing bone death. Most often, only one hip is affected. The oddity of this condition is that, without reason, the blood supply will often return after several months, causing the bone cells to regenerate over a few years.
Osteonecrosis
A less likely cause of hip and groin pain is osteonecrosis. According to the University of Maryland Medical Center, osteonecrosis, or bone death, most often occurs in the hip and shoulder resulting from poor blood supply to the joint. Osteonecrosis of the hip results in pain and weakness in the hip joint and groin area and can be associated with gout, atherosclerosis and diabetes.
Predominately found in the left hip, causes of osteonecrosis include extended steroid use, excessive alcohol intake, sickle cell disease, radiation therapy and decompression sickness as well as dislocations and fractures around the affected joint.
