Individuals affected by ischiopatellar dysplasia commonly have abnormalities of the patella and pelvic girdle, such as absent or delayed patellar and ischial ossification as well as infra-acetabular axe-cut notches. Patellae are typically absent or small in these individuals, when patellae are present they are small and laterally displaced or dislocated. In addition, abnormalities in other parts of their skeleton and dysmorphic features are common in those affected. Other features that have been identified in patients with ischiopatellar dysplasia include foot anomalies, specifically flat feet (pes planus), syndactylism of the toes, short fourth and fifth toes, and a large gap between the first and second toes, femur anomalies, cleft palate, and craniofacial dysmorphisms.

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.

The skeletal structures of individuals who have this disorder may have pronounced deformities. As reported by several medical doctors, the following features are commonly found in people who suffer from nail–patella syndrome:

Bones and joints

- Patellar involvement is present in approximately 90% of patients; however, patellar aplasia occurs in only 20%.

- In instances in which the patellae are smaller or luxated, the knees may be unstable.

- The elbows may have limited motion (e.g., limited pronation, supination, extension).

- Subluxation of the radial head may occur.

- Arthrodysplasia of the elbows is reported in approximately 90% of patients.

- General hyperextension of the joints can be present.

- Exostoses arising from the posterior aspect of the iliac bones ("iliac horns") are present in as many as 80% of patients; this finding is considered pathognomonic for the syndrome.

- Other reported bone changes include scoliosis, scapular hypoplasia, and the presence of cervical ribs.

Kidney issues may arise such as proteinuria and nephritis. Proteinuria is usually the first sign of renal involvement and either rapidly or years after suffering from asymptomatic proteinuria, renal failure occurs in around 5% of NPS patients. Hypothyroidism, irritable bowel syndrome, attention deficit hyperactivity disorder (ADHD), and thin tooth enamel are associated with NPS, but whether these are related or simply coincidences are unclear.

Ischiopatellar dysplasia is a rare autosomal dominant disorder characterized by a hypoplasia of the patellae as well as other bone anomalies, especially concerning the pelvis and feet.

A Malgaigne fracture is vertical pelvic fracture with bilateral sacroiliac dislocation and fracture of the pubic rami.

It is named for Joseph-François Malgaigne.

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.

Symptoms are related to defects in connective tissue.

- Congenital anterior dislocation of the knees

- Dislocation of hips and shoulders

- Flattened facial appearance

- Prominent forehead

- Depressed nasal bridge

- Club foot

- Cervical kyphosis

These symptoms were found in rare cases of Larsen syndrome.

- Cataracts

- Cleft palate

- Extra bones of wrist

- Malocclusion

- Microdontia and hypodontia

- Complete agenesis of anus

- uterus

- Bifid tongue

Nail–patella syndrome (NPS) (also known as "HOOD syndrome") is a genetic disorder that results in small, poorly developed nails and kneecaps, but can also affect many other areas of the body, such as the elbows, chest, and hips. The name "nail–patella" can be very misleading because the syndrome often affects many other areas of the body, including even the production of certain proteins. Those affected by NPS may have one or more affected areas of the body, and its severity varies depending on the individual. It is also referred to as iliac horn syndrome, hereditary onychoosteodysplasia (HOOD syndrome), Fong disease or Turner–Kieser syndrome.

Diagnosis of NPS can be made at birth, but is common for it to remain undiagnosed for several generations. While there is no cure available for NPS, treatment is available and recommended.

Chopart's fracture–dislocation is a dislocation of the mid-tarsal (talonavicular and calcaneocuboid) joints of the foot, often with associated fractures of the calcaneus, cuboid and navicular.

The condition is usually seen in athletic individuals typically between 10–14 years of age. Following a strain or partial rupture of patellar ligament the patient develops a traction ‘tendinitis’ characterized by pain and point tenderness at the inferior (lower) pole of the patella associated with focal swelling.

Children with cerebral palsy are particularly prone to SLJ 4.

Bipartite patella is a condition where the patella, or kneecap, is composed of two separate bones. Instead of fusing together as normally occurs in early childhood, the bones of the patella remain separated. The condition occurs in approximately 12% of the population and is nine times more likely to occur in males than females. It is often asymptomatic and most commonly diagnosed as an incidental finding, with about 2% of cases becoming symptomatic.

The symptoms can be numerous depending on the severity of the dislocation injury and how long the person is inflicted with the injury. Symptoms of a dislocated jaw include a bite that feels “off” or abnormal, hard time talking or moving jaw, not able to close mouth completely, drooling due to not being able to shut mouth completely, teeth feel they are out of alignment, and a pain that becomes unbearable

The immediate symptom can be a loud crunch noise occurring right up against the ear drum. This is instantly followed by excruciating pain, particularly in the side where the dislocation occurred.

Short-term symptoms can range from mild to chronic headaches, muscle tension or pain in the face, jaw and neck.

Long-term symptoms can result in sleep deprivation, tiredness/lethargy, frustration, bursts of anger or short fuse, difficulty performing everyday tasks, depression, social issues relating to difficulty talking, hearing sensitivity (particularly to high pitched sounds), tinnitus and pain when seated associated with posture while at a computer and reading books from general pressure on the jaw and facial muscles when tilting head down or up. And possible causing subsequent facial asymmetry.

In contrast, symptoms of a fractured jaw include bleeding coming from the mouth, unable to open the mouth wide without pain, bruising and swelling of the face, difficulty eating due to the constant pain, loss of feeling in the face (more specifically the lower lip) and lacks full range of motion of the jaw.

Synostosis (plural: synostoses) is fusion of two bones. It can be normal in puberty, fusion of the epiphysis, or abnormal. When synostosis is abnormal it is a type of dysostosis.

Examples of synostoses include:

- craniosynostosis – an abnormal fusion of two or more cranial bones;

- radioulnar synostosis – the abnormal fusion of the radius and ulna bones of the forearm;

- tarsal coalition – a failure to separately form all seven bones of the tarsus (the hind part of the foot) resulting in an amalgamation of two bones; and

- syndactyly – the abnormal fusion of neighboring digits.

Synostosis within joints can cause ankylosis.

Autosomal recessive multiple epiphyseal dysplasia (ARMED), also called epiphyseal dysplasia, multiple, 4 (EDM4), multiple epiphyseal dysplasia with clubfoot or –with bilayered patellae, is an autosomal recessive congenital disorder affecting cartilage and bone development. The disorder has relatively mild signs and symptoms, including joint pain, scoliosis, and malformations of the hands, feet, and knees.

Some affected individuals are born with an inward- and downward-turning foot (a clubfoot). An abnormality of the kneecap called a double-layered patella is also relatively common. Although some people with recessive multiple epiphyseal dysplasia have short stature as adults, most are of normal height. The incidence is unknown as many cases are not diagnosed due to mild symptoms.

Signs and symptoms of a dislocation or rotator cuff tear such as:

- Significant pain, which can sometimes be felt past the shoulder, along the arm.

- Inability to move the arm from its current position, particularly in positions with the arm reaching away from the body and with the top of the arm twisted toward the back.

- Numbness of the arm.

- Visibly displaced shoulder. Some dislocations result in the shoulder appearing unusually square.

- No bone in the side of the shoulder showing shoulder has become dislocated.

The Galeazzi fracture is a fracture of the distal third of the radius with dislocation of the distal radioulnar joint. It classically involves an isolated fracture of the junction of the distal third and middle third of the radius with associated subluxation or dislocation of the distal radio-ulnar joint; the injury disrupts the forearm axis joint.

Chopart's fracture–dislocation is usually caused by falls from height, traffic collisions and twisting injuries to the foot as seen in basketball players.

The Monteggia fracture is a fracture of the proximal third of the ulna with dislocation of the proximal head of the radius. It is named after Giovanni Battista Monteggia.

The Galeazzi fracture is named after Ricardo Galeazzi (1866–1952), an Italian surgeon at the Instituto de Rachitici in Milan, who described the fracture in 1934. However, it was first described in 1842, by Cooper, 92 years before Galeazzi reported his results.

Dislocations occur when two bones that originally met at the joint detach. Dislocations should not be confused with Subluxation. Subluxation is when the joint is still partially attached to the bone.

When a person has a dislocated jaw it is difficult to open and close the mouth. Dislocation can occur following a series of events if the jaw locks while open or unable to close. If the jaw is dislocated, it may cause an extreme headache or inability to concentrate. When the muscle's alignment is out of sync, a pain will occur due to unwanted rotation of the jaw.

If the pain remains constant, it may require surgery to realign the jaw. Depending on the severity of the jaw's dislocation, pain relief such as paracetamol may assist to alleviate the initial chronic pain. If the pain relief is taken for an extended period of time, it may negatively affect the person while talking, eating, drinking, etc.

Radioulnar synostosis is one of the more common failures of separation of parts of the upper limb. There are two general types: one is characterized by fusion of the radius and ulna at their proximal borders and the other is fused distal to the proximal radial epiphysis. Most cases are sporadic, congenital (due to a defect in longitudinal segmentation at the 7th week of development) and less often post-traumatic, bilateral in 60%, and more common in males. Familial cases in association with autosomal dominant transmission appear to be concentrated in certain geographic regions, such as Sicily.

The condition frequently is not noted until late childhood, as function may be normal, especially in unilateral cases. Increased wrist motion may compensate for the absent forearm motion. It has been suggested that individuals whose forearms are fixed in greater amounts of pronation (over 60 degrees) face more problems with function than those with around 20 degrees of fixation. Pain is generally not a problem, unless radial head dislocation should occur.

Most examples of radioulnar synostosis are isolated (non-syndromic). Syndromes that may be accompanied by radioulnar synostosis include X chromosome polyploidy (e.g., XXXY) and other chromosome disorders (e.g., 4p- syndrome, Williams syndrome), acrofacial dysostosis, Antley–Bixler syndrome, genitopatellar syndrome, Greig cephalopolysyndactyly syndrome, hereditary multiple osteochondromas (hereditary multiple exostoses), limb-body wall complex, and Nievergelt syndrome.

Craniosynostosis (from cranio, cranium; + syn, together; + ostosis relating to bone) is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses by turning into bone (ossification). Craniosynostosis has following kinds: scaphocephaly, trigonocephaly, plagiocephaly, anterior plagiocephaly, posterior plagiocephaly, brachycephaly, oxycephaly, pansynostosis.

Chondromalacia patellae (also known as CMP) is inflammation of the underside of the patella and softening of the cartilage.

The cartilage under the kneecap is a natural shock absorber, and overuse, injury, and many other factors can cause increased deterioration and breakdown of the cartilage. The cartilage is no longer smooth and therefore movement and use is painful. While it often affects young individuals engaged in active sports, it also afflicts older adults who overwork their knees.

"Chondromalacia patellae" is sometimes used synonymously with patellofemoral pain syndrome. However, there is general consensus that "patellofemoral pain syndrome" applies only to individuals without cartilage damage.

Attenuated patella alta is an extremely rare condition affecting mobility and leg strength. It is characterized by an unusually small knee cap (patella) that develops out of and above the joint. Normally, as the knee cap sits in the joint, it is stimulated to growth by abrasion from the opposing bones. When not situated properly in the joint, the knee cap does not experience such stimulation and remains small and undeveloped. Note that the cartilage under and around the kneecap is eight times smoother than ice, so "abrasion" may not be the best term.

A similar condition, patella alta, can occur as the result of a sports injury, though the large majority of the time it is a congenital/developmental condition that is unrelated to trauma. A kneecap in an "alta" position sits above the "trochlear groove" and therefore is less stable. The "patellar tendon" that connects the kneecap to the tibia (shinbone)is elongated (longer than normal). This cannot happen by way of trauma, unless there has been a rupture of the tendon and a less-than-optimal surgical repair.

There has been only one documented case of the disorder noted from birth. In 1988, three-year-old Eric Rogstad of Minneapolis, Minnesota was discovered to suffer from the condition in both knees after several attempts by his parents and family physician to discover the cause of his abnormal difficulties with walking and running. After surgery and physical therapy, Eric gained the ability to walk and run without significant difficulty.

Insall Ratio: This ratio is calculated with the knee flexed to 30 degrees. It is the ratio of the length of the patella to the length of the patellar tendon. Normally this ratio is 1:1 but 20% variation represents patella alta or patella infera. Actually, the Insall-Salvati ratio can be measured at any degree of flexion, which is one reason for its popularity.

Mechanisms include:

- Fall on an outstretched hand with the forearm in excessive pronation (hyper-pronation injury). The Ulna fractures in the proximal one-third of the shaft due to extreme dislocation. Depending on the impact and forces applied in each direction, degree of energy absorption determines pattern, involvement of the radial head and whether or not open soft tissue occurs.

- Direct blow on back of upper forearm would be a very uncommon cause. In this context, isolated ulnar shaft fractures are most commonly seen in defence against blunt trauma (e.g. nightstick injury). Such an isolated ulnar shaft fracture is "not" a Monteggia fracture. It is called a 'nightstick fracture'.