The hip is the area on the side of the buttock and is made up of several muscles, tendons, ligaments and bones. Hip pain is mainly due to disorders of the muscles, its tendons and or surrounding ligaments or may be due to the hip joint. The latter is more common and chronic hip joint problems are seen more frequently with advancing age. It is a common joint pain in the elderly. As one of the most mobile joint in the body and bearing the entire weight of the upper body along with additional strain with impact like running, the hip joint is prone to various problems. Pain can therefore be an indicator of many underlying diseases.
The hip joint is known as the acetabulofemoral joint. It is the point where the femur (thigh bone) articulates with the pelvic bone. The hip joint is a ball and socket synovial joint. The head of the femur is the “ball” while the acetabulum of the pelvis is the cup-like surface that serves as the “socket”. It is somewhat similar to the shoulder joint although it is much more stable given the deeper socket. As with any joint, cartilaginous surfaces allow for smoother articulation and prevents erosion of the bone itself. A capsule helps to secure the joint and allow for its smooth movement. It is further supported by several ligaments inside and outside the capsule. The surrounding muscles and its tendons also help to support the joint allowing it mobility only in certain axes as is required for different movements.
Overall the hip joint is a very ‘hardy’ joint and capable of withstanding considerable amounts of strain and ongoing wear and tear. However, it is prone to many of the same disorders and diseases of other tissues in the body that can lead to pain and limited mobility.
Signs and Symptoms
Hip pain is a symptom. It may vary intensity from just a mild ache to intense pain. Pain that is more superficial is more likely to be associated with the muscles and tendons while deeper lying pain is usually due to the bone pain or joint pain. The pain may be persistent and exacerbated with movement or only present during movement of the lower limb. Not all causes of hip pain stem from the joint, bones and surrounding muscles, tendons of ligaments. Therefore concomitant pain in the lower back, intergluteal cleft (between the buttocks), groin and abdomen may be referred pain to the hip.
Mobility may also be limited to varying degrees and this may be more pronounced with certain movements. Superficial symptoms such as swelling, redness of the skin, warmth and tenderness to touch is unlikely to be associated with the deeper structures such as the hip joint, pelvic bone or femur. It is more commonly isolated to the muscles and subcutaneous fat of the hip. A grinding, clicking or even popping sound may be audible usually with certain movements and is more commonly associated with the joint. A person may also report the sensation that the joint is grinding or popping but the latter is less common as the hip joint is deep and less likely to be dislocated as compared to the shoulder joint.
Causes of Hip Joint Pain
- Trauma. Injuries like falls are common particularly in the elderly and the hip is easily injured. This may be a soft tissue injury or an injury of the bone. A fracture or contusion may not be present but there can still be significant pain following the injury. Muscle strain and sprained ligaments may also be responsible for hip pain associated with trauma.
- Overuse and wear-and-tear occurs over time and is almost entirely seen in the elderly. The hip joint is a common site for these age-related changes and may be further exacerbated by underlying diseases like arthritis.
- Fractures. A fracture may occur in the femur or pelvis.It is more common in the elderly as the bones become weaker with conditions like osteoporosis. Although fractures can affect just about any part of the femur and pelvis, the femoral neck between the head and shaft of the femur is one of the weaker points that is worth noting specifically.
- Hip dislocation is not as common as shoulder dislocation due to the deeper socket of the hip joint. However, it can occur and is a very painful condition. The head of the femur more commonly slips out in a backward direction (posterior dislocation) but may also occur in a frontward direction (anterior dislocation).
- Arthritis is inflammation of the joint which may be associated with a number of different mechanisms. This includes rheumatoid arthritis, osteoarthritis or septic arthritis.
- Bursitis is inflammation of the fluid-filled sac near the joints and other surfaces where the body tissues may rub against each other. Hip pain could be due to bursitis at several sites in the region – trochanteric, ischiogluteal or iliopectineal. The term is sometimes used interchangeably with synovitis – inflammation of the membrane lining the joint – since bursae also have a syonvial lining.
- Trochanteric bursitis occurs at the protrusion on the outer side of the upper part of the femur known as the greater troachanter. Pain is therefore worse on the upper outer part of the thigh.
- Ischiogluteal bursitis occurs at the upper back part of the thigh where it meets the buttock. The pain is felt deep in the buttock. It is also commonly referred to as weaver’s bottom.
- Iliopectineal bursitis involves the large bursa at the front of the the hip joint and pubis. Pain is therefore prominent on the front of the groin and may at times be described as pain between the hip and genitals.
- Tendinitis is the inflammation of the muscle tendons. With the hip surrounded by some of the largest muscles of the body and these muscles having to work hard as it bears the weight of the body and propels the body as a whole, tendinitis can be a common cause of hip pain.
- Adductor tendinitis is due to strain of the adductor muscles and its tendons. Read more on thigh muscles. It is a common problem in physically active people and sporting professionals. It may also be caused by overstretching of the adductors. Gluteal tendinitis may also occur for largely the same reasons.
- Enthesitis or enthesopathy is a inflammation at the site of the bone where the tendons or ligaments attach. It may overlap with tendinitis and is therefore discussed here. Gluteal enthesopathy is one of the more common enthesopathies that accounts for hip pain.
- Bone pain involves conditions like osteoporosis, osteomalacia (adults), rickets (children), osteomyelitis, Paget’s disease and avascular necrosis. Depending on the type of bone disease, it may also increase the risk of injury to the bone and fractures.
- Back pain can radiate to the hip and down the thigh.
- Nerve root entrapment (pinched nerve) at the level of T12 to L1 can cause back pain extending down the lateral aspect (outer side) of the thigh.
- When the level at L2 to L4 is affected, there may be inguinal pain in addition to lateral thigh pain.
- Compression of the lower lumbar and sacral nerves may give rise to sciatica that can also contribute to hip pain.
- Sacroiliac pain, often termed buttock pain, may also present with the pain radiating down the posterior aspect (back) of the thigh.
- Referred pain to the thigh may arise from :
- Pelvic inflammatory disease
- Retroperitoneal hemorrhage
- Psoas abscess
- Cancer of the pelvic bone or femur can also cause hip pain. The cancer may be primary (starting in the hip bones) or secondary (metastatic spread from a distant site). Osteosarcoma and chondrosarcoma are the more common types of cancers to affect the hip bones. Leukemia may also cause hip pain, particularly of the femur.