Hip dysplasia can range from barely detectable to severely malformed or dislocated.

The congenital form, teratologic or non-reducible dislocation occurs as part of more complex conditions.

The condition can be bilateral or unilateral:

- If both hip joints are affected one speaks of "bilateral" dysplasia. In this case some diagnostic indicators like asymmetric folds and leg-length inequality do not apply.

- In unilateral dysplasia only one joint shows deformity, the contralateral side may show resulting effects. In the majority of unilateral cases the left hip has the dysplasia.

If the joint is fully dislocated a false acetabulum often forms (often higher up on the pelvis) opposite the dislocated femoral head position.

In acetabular dysplasia the acetabulum (socket) is too shallow or deformed. The center-edge angle is measured as described by Wiberg. Two forms of femoral dysplasia are coxa vara, in which the femur head grows at too narrow an angle to the shaft, and coxa valga, in which the angle is too wide.

A rare type, the "Beukes familial hip dysplasia" is found among Afrikaners that are members of the Beukes family. The femur head is flat and irregular. People develop osteoarthritis at an early age.

Elbow dysplasia is a condition involving multiple developmental abnormalities of the elbow-joint in the dog, specifically the growth of cartilage or the structures surrounding it. These abnormalities, known as 'primary lesions', give rise to osteoarthritic processes. Elbow dysplasia is a common condition of certain breeds of dogs.

Most primary lesions are related to osteochondrosis, which is a disease of the joint cartilage and specifically Osteochondritis dissecans (OCD or OD), the separation of a flap of cartilage on the joint surface. Other common causes of elbow dysplasia included ununited anconeal process (UAP) and fragmented or ununited medial coronoid process (FCP or FMCP).

Osteochondritis dissecans is difficult to diagnose clinically as the animal may only exhibit an unusual gait. Consequently, OCD may be masked by, or misdiagnosed as, other skeletal and joint conditions such as hip dysplasia. The problem develops in puppyhood although often subclinically, and there may be pain or stiffness, discomfort on extension, or other compensating characteristics. Diagnosis generally depends on X-rays, arthroscopy, or MRI scans. While cases of OCD of the stifle go undetected and heal spontaneously, others are exhibited in acute lameness. Surgery is recommended once the animal has been deemed lame, before then non-surgical control is usually used.

Petplan Australia reported that signs of arthritis in dogs and cats include stiffness, difficulty moving, lethargy, irritability, and cat or dog may lick, chew or bite at sore joints.

Dogs might exhibit signs of stiffness or soreness after rising from rest, reluctance to exercise, bunny-hopping or other abnormal gait (legs move more together when running rather than swinging alternately), lameness, pain, reluctance to stand on rear legs, jump up, or climb stairs, subluxation or dislocation of the hip joint, or wasting away of the muscle mass in the hip area. Radiographs (X-rays) often confirm the presence of hip dysplasia, but radiographic features may not be present until two years of age in some dogs. Moreover, many affected dogs do not show clinical signs, but some dogs manifest the problem before seven months of age, while others do not show it until well into adulthood.

In part this is because the underlying hip problem may be mild or severe, may be worsening or stable, and the body may be more or less able to keep the joint in repair well enough to cope. Also, different animals have different pain tolerances and different weights, and use their bodies differently, so a light dog who only walks, will have a different joint use than a more heavy or very active dog. Some dogs will have a problem early on, others may never have a real problem at all.

Usually, a SCFE causes groin pain, but it may cause pain in only the thigh or knee, because the pain may be referred along the distribution of the obturator nerve. The pain may occur on both sides of the body (bilaterally), as up to 40 percent of cases involve slippage on both sides. After a first SCFE, when a second SCFE occurs on the other side, it typically happens within one year after the first SCFE. About 20 percent of all cases include a SCFE on both sides at the time of presentation.

Signs of a SCFE include a waddling gait, decreased range of motion. Often the range of motion in the hip is restricted in internal rotation, abduction, and flexion. A person with a SCFE may prefer to hold their hip in flexion and external rotation.

Elbow Dysplasia is a significant genetically determined problem in many breeds of dog, often manifesting from puppyhood and continuing for life. In elbow dysplasia, the complex elbow joint suffers from a structural defect, often related to its cartilage. This initial condition, known as a "primary lesion", causes an abnormal level of wear and tear and gradual degradation of the joint, at times disabling or with chronic pain. Secondary processes such as inflammation and osteoarthritis can arise from this damage which increase the problem and add further problems of their own.

Hip dysplasia is an abnormality of the hip joint where the socket portion does not fully cover the ball portion, resulting in an increased risk for joint dislocation. Hip dysplasia may occur at birth or develop in early life. Regardless, it does not typically produce symptoms in babies less than a year old. Occasionally one leg may be shorter than the other. The left hip is more often affected than the right. Complications without treatment can include arthritis, limping, and low back pain.

Risk factors for hip dysplasia include family history, certain swaddling practices, and breech birth. If one identical twin is affected, there is a 40% risk the other will also be affected. Screening all babies for the condition by physical examination is recommended. Ultrasonography may also be useful.

Many of those with mild instability resolve without specific treatment. In more significant cases, if detected early, bracing may be all that is required. In cases that are detected later, surgery and casting may be needed. About 7.5% of hip replacements are done to treat problems which have arisen from hip dysplasia.

About 1 in 1,000 babies have hip dysplasia. Hip instability of meaningful importance occurs in one to two percent of babies born at term. Females are affected more often than males. Hip dysplasia was described at least as early as the 300s BC by Hippocrates.

In the normal anatomy of the hip joint, the root (the thigh bone) is connected to the pelvis at the hip joint. The almost spherical end of the femur head (the caput, or caput ossis femoris) fits into the acetabulum (a concave socket located in the pelvis). The bony surfaces of the femur head and of the acetabulum are covered by cartilage. While bones provide the strength necessary to support body weight, cartilage ensures a smooth fit and a wide range of motion. Normal hip function can be affected by congenital conditions such as dysplasia, discussed in this article, trauma, and by acquired diseases such as osteoarthritis and rheumatoid arthritis.

Failure to treat a SCFE may lead to: death of bone tissue in the femoral head (avascular necrosis), degenerative hip disease (hip osteoarthritis), gait abnormalities and chronic pain. SCFE is associated with a greater risk of arthritis of the hip joint later in life. 17-47 percent of acute cases of SCFE lead to the death of bone tissue (osteonecrosis) effects.

Common symptoms include hip, knee (hip pathology can refer pain to a normal knee), or groin pain, exacerbated by hip or leg movement, especially internal hip rotation (with the knee flexed 90°, twisting the lower leg away from the center of the body). The range of motion is reduced, particularly in abduction and internal rotation, and the patient presents with a limp. Pain is usually mild. Atrophy of thigh muscles may occur from disuse and an inequality of leg length. In some cases, some activity can cause severe irritation or inflammation of the damaged area, including standing, walking, running, kneeling, or stooping repeatedly for an extended period of time. In cases exhibiting severe femoral osteonecrosis, pain is usually a chronic, throbbing sensation exacerbated by activity.

The first signs are complaints of soreness from the child, which are often dismissed as growing pains, and limping or other guarding of the joint, particularly when tired. The pain is usually in the hip, but can also be felt in the knee (referred pain). In some cases, pain is felt in the unaffected hip and leg, due to the children favoring their injured side and placing the majority of their weight on their "good" leg. It is predominantly a disease of boys (4:1 ratio). Perthes is generally diagnosed between 5 and 12 years of age, although it has been diagnosed as early as 18 months. Typically, the disease is only seen in one hip, but bilateral Perthes is seen in about 10% of children diagnosed.

Children with autosomal dominant MED experience joint pain and fatigue after exercising. Their x-rays show small and irregular ossifications centers, most apparent in the hips and knees. A waddling gait may develop. Flat feet are very common.

The spine is normal but may have a few irregularities, such as scoliosis. There are very small capital femoral epiphyses and hypoplastic, poorly formed acetabular roofs. Knees have metaphyseal widening and irregularity while hands have brachydactyly (short fingers) and proximal metacarpal rounding. By adulthood, people with MED are of short stature or in the low range of normal and have short limbs relative to their trunks. Frequently, movement becomes limited at the major joints, especially at the elbows and hips. However, loose knee and finger joints can occur. Signs of osteoarthritis usually begin in early adulthood.

Children with recessive MED experience joint pain, particularly of the hips and knees, and commonly have deformities of the hands, feet, knees, or vertebral column (like scoliosis). Approximately 50% of affected children have abnormal findings at birth (such as club foot or twisted metatarsals, cleft palate, inward curving fingers due to underdeveloped bones and brachydactyly, or ear swelling caused by injury during birth). Height is in the normal range before puberty. As adults, people with recessive MED are only slightly more diminished in stature, but within the normal range. Lateral knee radiography can show multi-layered patellae.

The classic clinical presentation of a hip fracture is an elderly patient who sustained a low-energy fall and now has groin pain and is unable to bear weight. Pain may be referred to the supracondylar knee. On examination, the affected extremity is often shortened and unnaturally, externally rotated compared to the unaffected leg.

Femoroacetabular Impingement (FAI), or hip impingement syndrome, may affect the hip joint in young and middle-aged adults and occurs when the ball shaped femoral head rubs abnormally or does not permit a normal range of motion in the acetabular socket. Damage can occur to the articular cartilage, or labral cartilage (soft tissue bumper of the socket), or both. Treatment options range from conservative to arthroscopic to open surgery.

Coxa vara is a deformity of the hip, whereby the angle between the head and the shaft of the femur is reduced to less than 120 degrees. This results in the leg being shortened, and the development of a limp. It is commonly caused by injury, such as a fracture. It can also occur when the bone tissue in the neck of the femur is softer than normal, causing it to bend under the weight of the body. This may either be congenital or the result of a bone disorder. The most common cause of coxa vara is either congenital or developmental. Other common causes include metabolic bone diseases (e.g. Paget's disease of bone), post-Perthes deformity, osteomyelitis, and post traumatic (due to improper healing of a fracture between the greater and lesser trochanter). Shepherd's Crook deformity is a severe form of coxa vara where the proximal femur is severely deformed with a reduction in the neck shaft angle beyond 90 degrees. It is most commonly a sequela of osteogenesis imperfecta, Pagets disease, osteomyelitis, tumour and tumour-like conditions (e.g. fibrous dysplasia).

Coxa vara can happen in cleidocranial dysostosis.

Legg–Calvé–Perthes disease (LCPD, also known as Perthes disease or Legg–Perthes disease) is a childhood hip disorder initiated by a disruption of blood flow to the head of the femur. Due to the lack of blood flow, the bone dies (osteonecrosis or avascular necrosis) and stops growing. Over time, healing occurs by new blood vessels infiltrating the dead bone and removing the necrotic bone which leads to a loss of bone mass and a weakening of the femoral head. The bone loss leads to some degree of collapse and deformity of the femoral head and sometimes secondary changes to the shape of the hip socket. It is also referred to as idiopathic avascular osteonecrosis of the capital femoral epiphysis of the femoral head since the cause of the interruption of the blood supply of the head of the femur in the hip joint is unknown.

The condition is most commonly found in children between the ages of 4 and 8, but it can occur in children between the ages of 2 and 15. The main long-term problem with this condition is that it can produce a permanent deformity of the femoral head, which increases the risk of developing osteoarthritis in adults. Perthes is a form of osteochondritis which only affects the hip, although other forms of osteochondritis can affect elbows, knees, ankles, and feet. Bilateral Perthes, which means both hips are affected, should always be investigated thoroughly to rule out multiple epiphyseal dysplasia.

A hip fracture is a break that occurs in the upper part of the femur (thigh bone). Symptoms may include pain around the hip particularly with movement and shortening of the leg. Usually the person cannot walk.

They most often occur as a result of a fall. Risk factors include osteoporosis, taking many medications, alcohol use, and metastatic cancer. Diagnosis is generally by X-rays. Magnetic resonance imaging, a CT scan, or a bone scan may occasionally be required to make the diagnosis.

Pain management may occur with opioids or a nerve block. If a person's health is sufficient, surgery is generally recommended within two days. Options for surgery may include a total hip replacement or screws. Efforts to prevent deep vein thrombosis following surgery are recommended.

About 15% of women break their hip at some point in their life. Women are more often affected than men. Hip fractures become more common with age. The risk of death in the year following a fracture is about 20% in older people.

In many cases there is pain and discomfort in a joint which increases over time. While it can affect any bone, about half of cases show multiple sites of damage. Avascular necrosis primarily affects the joints at the shoulder, knee, and hip. The classical sites are: head of femur, neck of talus and waist of the scaphoid.

Avascular necrosis most commonly affects the ends of long bones such as the femur (the bone extending from the knee joint to the hip joint). Other common sites include the humerus (the bone of the upper arm), knees, shoulders, ankles and the jaw.

FAI-related pain is often felt in the groin, but may also be experienced in the lower back or around the hip. The diagnosis, often with a co-existing labral tear, typically involves physical examination in which the range of motion of the hip is tested. Limited flexibility leads to further examination with x-ray, providing a two-dimensional view of the hip joints. Additional specialized views, such as the Dunn view, may make x-ray more sensitive. Subsequent imaging techniques such as CT or MRI may follow producing a three-dimensional reconstruction of the joint to evaluate the hip cartilage, demonstrate signs of osteoarthritis, or measure hip socket angles (e.g. the alpha-angle as described by Nötzli in 2-D and by Siebenrock in 3-D). It is also possible to perform dynamic simulation of hip motion with CT or MRI assisting to establish whether, where, and to what extent, impingement is occurring.

The affected leg is virtually immovable by the patient, and is usually extremely painful. Dislocations are categorized as either posterior or anterior, based on the location of the head of the femur (see classification above).

Dislocation of the hip is a common injury to the hip joint. Dislocation occurs when the ball–shaped head of the femur comes out of the cup–shaped acetabulum set in the pelvis.

Dislocations may be developmental or due to acute trauma. The emphasis of this article is on acute dislocation. For developmental dislocation, see hip dysplasia.

Acute traumatic hip dislocations are severe injuries. These dislocations typically occur in 16- to 40-year-olds involved in high energy trauma like motor vehicle accidents.

Juvenile rheumatoid arthritis presents gradually with early morning stiffness, fatigue, and weight loss.

Transient synovitis is a reactive arthritis of the hip of unknown cause. People are usually able to walk and may have a low grade fever. They usually look clinically nontoxic or otherwise healthy. It may only be diagnosed once all other potential serious causes are excluded. With symptomatic care it usually resolves over one week.

In early skeletal development, a common physis serves the greater trochanter and the capital femoral epiphysis. This physis divides as growth continues in a balance that favors the capital epiphysis and creates a normal neck shaft angle (angle between the femoral shaft and the neck). The corresponding angle at maturity is 135 ± 7 degrees. Another angle used for the measurement of coxa vara is the cervicofemoral angle which is approximately 35 degrees at infancy and increases to 45 degrees after maturity.

Fairbank's disease or multiple epiphyseal dysplasia (MED) is a rare genetic disorder (dominant form: 1 in 10,000 births) that affects the growing ends of bones. Long bones normally elongate by expansion of cartilage in the growth plate (epiphyseal plate) near their ends. As it expands outward from the growth plate, the cartilage mineralizes and hardens to become bone (ossification). In MED, this process is defective.

Avascular necrosis (AVN), also called osteonecrosis or bone infarction, is death of bone tissue due to interruption of the blood supply. Early on there may be no symptoms. Gradually joint pain may develop which may limit the ability to move. Complication may include collapse of the bone or nearby joint surface.

Risk factors include bone fractures, joint dislocations, alcoholism, and the use of high dose steroids. The condition may also occur without any clear reason. The most commonly affected bone is the femur. Other relatively common sites include the upper arm bone, knee, shoulder, and ankle. Diagnosis is typically by medical imaging such as X-ray, CT scan, or MRI. Rarely biopsy may be used.

Treatments may include medication, not walking on the affected leg, stretching, and surgery. Most of the time surgery is eventually required and may include core decompression, osteotomy, bone grafts, or joint replacement. About 15,000 cases occur per year in the United States. People 30 to 50 years old are most commonly affected. Males are more commonly affected than females.

In some cases, an audible snapping or popping noise as the tendon at the hip flexor crease moves from flexion (knee toward waist) to extension (knee down and hip joint straightened). After extended exercise pain or discomfort may be present caused by inflammation of the iliopsoas bursae. Pain often decreases with rest and diminished activity. Symptoms usually last months or years without treatment and can be very painful.