Known as a “ball and socket” joint, the hip joint is the place where the rounded top of the thighbone sits in the cup-like cavity in the pelvis. Cushioned by cartilage and surrounded by muscles, ligaments, tendons and other tissue that are responsible for protecting the joint and facilitating its movement, the hip joint is susceptible to problems when any of these structures is affected by injury or disease.
Participation in athletics, an accident or fall, overuse or a sudden increase in activity level can all cause injury to the hip joint. In some cases, the muscles or tendons surrounding the joint may tear, resulting in a strain or sprain. In more severe instances, one or more bones in the hip, pelvis or thigh may fracture or become dislocated, impairing the way the top of the ball-shaped thighbone normally fits into the concave portion of the pelvis. According to Medline Plus, a thin sac called a bursa that cushions the bones at the hip joint may also swell in response to injury, leading to a condition known as bursitis. Inflammation limits movement at the joint and can cause significant pain and tenderness.
Congenital Hip Dysplasia
Congenital hip dysplasia--sometimes referred to as developmental dysplasia of the hip, or DDH--is a condition present at the time of birth that causes a dislocation of the hip joint. Though the exact cause is unknown, genetic abnormalities or insufficient amniotic fluid in the womb during pregnancy may play a role, according to Medline Plus. The condition is usually diagnosed in infancy or early childhood and may require a re-positioning cast or surgery to correct.
Slipped Capital Femoral Epiphysis
Slipped capital femoral epiphysis is a condition that occurs when the top of the thighbone dislodges from its position in the hip joint. According to FamilyDoctor.org, this condition usually occurs among adolescents between ages 8 and 15, and is more common among boys than girls. Though the cause is unknown, slipped capital femoral epiphysis is associated with children who are overweight, and it can sometimes develop acutely after trauma or a fall.
Transient Osteoporosis of the Hip
Osteoporosis is a chronic condition characterized by irreversible loss of bone density over time. According to the American Academy of Orthopaedic Surgeons, a temporary and reversible type of osteoporosis known as transient osteoporosis of the hip sometimes comes on acutely with no apparent cause. The condition causes a sudden onset of severe pain in the hip joint or thigh, along with loss of motion and difficulty walking. The condition can sometimes take six to 12 months to resolve on its own.
Osteoarthritis is a common joint disorder that causes inflammation of the hip joint. The more the joint tissues swell, the more difficult it is to move the hip, resulting in stiffness and loss of motion. According to the University of California-San Francisco Medical Center, osteoarthritis also causes degeneration of cartilage at the joints, leading the bones to rub together at the hip. As the condition progresses, it can cause severe pain, muscle weakness and malformations of the hip joint.
Adhesive Capsulitis of the Hip
Adhesive capsulitis--commonly called “frozen shoulder”--is a condition that's most well known for affecting the shoulder. However, results from a study published in the January 2006 issue of “Arthroscopy: The Journal of Arthroscopic and Related Surgery” reveal that the condition also affects the hips at a rate greater than previously thought by doctors and researchers. Adhesive capsulitis of the hip, or “frozen hip," causes pain in the hip joint along with severely restricted motion. The condition is most common among middle-aged women and usually comes on suddenly with no clear cause.