Hips are interdependent with other lower body joints for function. When the hip moves, the knee and ankle typically do as well. This coordination facilitates walking and balance. The upper body also supports walking and balance through interactions with the leg joints. Bones link together, muscles work in unison, and nerves connect it all by control from the brain.
Much like the shoulder joint, the hip joints have unique issues that can occur, especially with paralysis. This can be paralysis on one side of the body from stroke or head injury or paralysis on both sides of the body as in complete or incomplete spinal cord injury from trauma or disease.
Subluxation of the hip is much the same as subluxation in the shoulder. A leg or both legs with mobility issues can lead to muscles that relax. Without the muscle holding the ball at the top of the femur bone in the hip socket, the joint becomes loose, allowing the ball to slip a bit from the socket. You will feel anything from slight to severe pain if you have a sensation. If you have issues with sensation, you may have referred pain in your shoulder or jaw or episodes of tone (spasticity) or autonomic dysreflexia. When moving the joint, you might hear a pop or crackle as the bones rub together. Range of motion will become less as the ball no longer turns in the socket. Much like a dislocated hip, the leg with a hip subluxation can become shorter with the leg turned inward or outward in a resting position.
Testing for subluxation is done by physical examination of moving the leg. The leg should not be moved if the joint is not freely functioning except by a healthcare professional. You do not want to force a joint that is not functional to avoid further injury. An x-ray or CT scan may be done to look for fracture or detain of the subluxation.
If there is no fracture or broken bone, an orthopedic surgeon or other physician may be able to move the ball back into the socket through manipulation of the leg. You may be prescribed a splint to wear to hold the joint in place. If there is a fracture of the bone(s), surgery may be needed to move muscles or replace the hip joint. Therapy will be prescribed to strengthen the muscles to continue to hold the joint in place.
Contracture is a shortening or loss of flexibility of a muscle. Contractures are often seen in individuals with high tone (spasticity) as in high level spinal cord injury, stroke, or brain injury affecting the upper motor neurons. Individuals with tone (spasticity) can develop a contracture if the muscle is not stretched. Always being positioned with the hip flexibly can lead to contractures in individuals who have tone, especially sitting for long periods or laying with their hips flexed.
Stretching is critical to maintaining the flexibility of the hip muscles. When stretching the muscles, know the normal range of motion of the hip joints, and all the joints, to ensure the muscle is not developing a contracture. If a contracture develops, serial stretching or even surgery may be needed to restore the joint to its capacity.
Flaccid hip joint occurs in individuals who have less to absent tone in their bodies. This can be seen in individuals with lower-level spinal cord injury or brain injury affecting the lower motor neurons. In this case, the individual’s hip and leg have little to no tone, so they dangle. The ability to stretch the hip is greater as there is no resistance, but stretching too far can damage muscles and nerves. Knowing the range of motion of an individual can prevent such injury.
Dislocation of the hip occurs when the ball is completely out of the socket joint. This can occur from subluxation or trauma like falling on your hip, someone pulling your body weight by your leg, adapted sports, arthritis, or untreated osteoporosis, but the most common cause is in a vehicle accident. Some individuals who have a head injury or spinal cord injury from trauma also have their hip dislocated due to the force of the accident. Arthritis and osteoporosis are also culprits.
The majority of hip dislocations occur with the hip out of the socket toward the back of the joint. The leg is unable to move. The knee and foot rotate inward. Less often, the hip can dislocate toward the front of the socket. The hip will look slightly bent in the resting position. The knee and foot rotate outward.
Hip dislocation is extremely painful, although some other individuals have no pain at all. If you have issues with sensation, you may not feel pain but have referred pain, increased tone, or episodes of AD.
Dislocation is readily seen by looking at your hip. Diagnostic aids are x-ray and CT scan. Since hip dislocations affect surrounding tissue, nerves can be injured. Therefore, electromyogram (EMG) and nerve conduction studies (NCS) may be done.