Some studies suggest a hormonal link. Specifically, the hormone relaxin has been indicated.

A genetic factor is indicated since the trait runs in families and there is an increased occurrence in some ethnic populations (e.g., Native Americans, Lapps / Sami people). A locus has been described on chromosome 13. Beukes familial dysplasia, on the other hand, was found to map to an 11-cM region on chromosome 4q35, with nonpenetrant carriers not affected.

Hip dysplasia is considered to be a multifactorial condition. That means that several factors are involved in causing the condition to manifest.

The cause of this condition is unknown; however, some factors of congenital hip dislocation are through heredity and racial background. It is also thought that the higher rates in some ethnic groups (such as some Native American groups) is due to the practice swaddling of infants, which is known to be a potential risk factor for developing dysplasia. It also has a low risk in African Americans and southern Chinese.

After an anterior shoulder dislocation, the risk of a future dislocation is about 20%. This risk is greater in males than females.

It is sometimes possible to correct the problem with surgery, though this has high failure rates for treatment of post-traumatic radioulnar synostosis.

The cause of PFFD is uncertain. Two hypotheses have been advanced. The theory of sclerotome subtraction posits injury to neural crest cells that are the precursors to sensory nerves at the level of L4 and L5. Histologic studies of a fetus with unilateral PFFD have prompted an alternative hypothesis that PFFD is caused by a defect in maturation of chondrocytes (cartilage cells) at the growth plate. In either hypothesis, the agent causing the injury is usually not known. Thalidomide is known to cause PFFD when the mother is exposed to it in the fifth or sixth week of pregnancy, and it is speculated that exposure to other toxins during pregnancy may also be a cause. Other etiologies that have been suggested, but not proven, include anoxia, ischemia, radiation, infection, hormones, and mechanical force. PFFD occurs sporadically, and does not appear to be hereditary.

Post-traumatic cases are most likely to develop following surgery for a forearm fracture, this is more common with high-energy injuries where the bones are broken into many pieces (comminuted). It can also develop following soft tissue injury to the forearm where there is haematoma formation.

Hip fractures are seen globally and are a serious concern at the individual and population level. By 2050 it is estimated that there will be 6 million cases of hip fractures worldwide. One study published in 2001 found that in the US alone, 310,000 individuals were hospitalized due to hip fractures, which can account for 30% of Americans who were hospitalized that year. Another study found that in 2011, femur neck fractures were among the most expensive conditions seen in US hospitals, with an aggregated cost of nearly $4.9 billion for 316,000 inpatient hospitalizations. Rates of hip fractures is declining in the United States, possibly due to increased use of bisphosphonates and risk management. Falling, poor vision, weight and height are all seen as risk factors. Falling is one of the most common risk factors for hip fractures. Approximately 90% of hip fractures are attributed to falls from standing height.

Given the high morbidity and mortality associated with hip fractures and the cost to the health system, in England and Wales, the National Hip Fracture Database is a mandatory nationwide audit of care and treatment of all hip fractures.

The majority of hip fractures are the result of a fall, particularly in the elderly. Therefore, identifying why the fall occurred, and implementing treatments or changes, is key to reducing the occurrence of hip fractures. Multiple contributing factors are often identified. These can include environmental factors and medical factors (such as postural hypotension or co-existing disabilities from disease such as Stroke or Parkinson's Disease which cause visual and/or balance impairments). A recent study has identified a high incidence of undiagnosed cervical spondylotic myelopathy (CSM) amongst patients with a hip fracture. This is relatively unrecognised consequent of CSM.

Additionally, there is some evidence to systems designed to offer protection in the case of a fall. Hip protectors, for example appear to decrease the number of hip fractures among the elderly. They; however, are not often used.

Jaw dislocation is common for people who are in car, motorcycle or related accidents and also sports related activities. This injury does not pin point specific ages or genders because it could happen to anybody. People who dislocate their jaw do not usually seek emergency medical care. In most cases, jaw dislocations are acute and can be altered by minor manipulations. It was reported from one study that over a seven-year period at an emergency medical site, with 100,000 yearly visits, there were only 37 patients that were seen for a dislocated jaw.

The incidence of Hill–Sachs lesion is not known with certainty. It has been reported to be present in 40% to 90% of patients presenting with anterior shoulder instability, that is subluxation or dislocation. In those who have recurrent events, it may be as high as 100%. Its presence is a specific sign of dislocation and can thus be used as an indicator that dislocation has occurred even if the joint has since regained its normal alignment. The average depth of Hill–Sachs lesion has been reported as 4.1 mm. Large, engaging Hill-Sachs fractures can contribute to shoulder instability and will often cause painful clicking, catching, or popping.

Rate in the United States have been estimated to occur among an at-risk population of 1,774,210,081 people each year. Incidence rates published in the American Journal of Sports Medicine for ages 10–17 were found to be about 29 per 100,000 persons per year, while the adult population average for this type of injury ranged between 5.8 and 7.0 per 100,000 persons per year. The highest rates of patellar dislocation were found in the youngest age groups, while the rates declined with increasing ages. Females are more susceptible to patellar dislocation. Race is a significant factor for this injury, where Hispanics, African-Americans and Caucasians had slightly higher rates of patellar dislocation due to the types of athletic activity involved in: basketball (18.2%), soccer (6.9%), and football (6.9%), according to Brian Waterman.

Lateral Patellar dislocation is common among the child population. Some studies suggest that the annual patellar dislocation rate in children is 43/100,000. The treatment of the skeletally immature is controversial due to the fact that they are so young and are still growing. Surgery is recommended by some experts in order to repair the medial structures early, while others recommend treating it non operatively with physical therapy. If re-dislocation occurs then reconstruction of the medial patellofemoral ligament (MPFL) is the recommended surgical option.

FAI has been speculated as a cause of premature hip osteoarthritis and is characterized by abnormal contact between the proximal femur and rim of the acetabulum (hip socket). In most cases, patients present with a deformity in the femoral head, or acetabulum, a poorly positioned femoral-acetabular junction, or any or all of the foregoing. A combination of certain factors may predispose to some form of FAI, predominantly, a marginal developmental hip abnormality together with environmental factors such as activities involving recurrent motion of the legs within a supraphysiologic range.

Three types of FAI are recognized. The first involves an excess of bone along the upper surface of the femoral head, known as a Cam deformity (abbreviation for camshaft which the shape of the femoral head and neck resembles). The second is due to an excess of growth of the upper lip of the acetabular cup and is known as a 'Pincer' deformity. Colloquially, these are referred to as 'Cam' and 'Pincer'. The third is a combination of the two, generally referred to as 'Mixed'. Studies have suggested that 'Cam' deformities are more common in the male, while 'Pincer' deformities are more common in females. However, the most common situation, approximately 70%, is a combination of both. A complicating issue is that some of the radiographic findings of FAI have also been described in asymptomatic subjects. Consequently, the true frequency of femoroacetabular impingement is currently under debate, but the ultimate result is increased friction between the acetabular cup and femoral head which may result in pain and loss or reduction of hip function.

Hip dysplasia may be caused by a femur that does not fit correctly into the pelvic socket, or poorly developed muscles in the pelvic area. Large and giant breeds are most susceptible to hip dysplasia (possibly due to the body mass index (BMI) of the individual animal, though, many other breeds can suffer from it. The Orthopedic Foundation for Animals maintains a list of top 100 breeds affected.

To reduce pain, the animal will typically reduce its movement of that hip. This may be visible as "bunny hopping", where both legs move together, or less dynamic movement (running, jumping), or stiffness. Since the hip cannot move fully, the body compensates by adapting its use of the spine, often causing spinal, stifle (a dog's knee joint), or soft tissue problems to arise.

The causes of hip dysplasia are considered heritable, but new research conclusively suggests that environment also plays a role. To what degree the causality is genetic and what portion environmental is a topic of current debate. Neutering a dog, especially before the dog has reached an age of full developmental maturity, has been proven to almost double the chance he or she will develop hip dysplasia versus intact dogs or dogs that were neutered after reaching adulthood Other environmental influences include overweight condition, injury at a young age, overexertion on the hip joint at a young age, ligament tear at a young age, repetitive motion on forming joint (i.e. jogging with puppy under the age of 1 year). As current studies progress, greater information may help provide procedures to effectively reduce the occurrence of this condition.

The problem almost always appears by the time the dog is 18 months old. The defect can be anywhere from mild to severely crippling, and can eventually cause severe osteoarthritis.

It is most common in medium-large pure bred dogs, such as Newfoundlands, German Shepherd Dogs, retrievers (such as Labradors, Tollers, or Goldens), rottweilers and Mastiff, but also occurs in some smaller breeds such as spaniels and pugs.

There are typically four classes (or "types") of PFFD, ranging from class A to class D, as detailed by Aitken.

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.

In children, whose bones are still developing, there are risks of either a growth plate injury or a greenstick fracture.

- A greenstick fracture occurs due to mechanical failure on the tension side. That is, since the bone is not so brittle as it would be in an adult, it does not completely fracture, but rather exhibits bowing without complete disruption of the bone's cortex in the surface opposite the applied force.

- Growth plate injuries, as in Salter-Harris fractures, require careful treatment and accurate reduction to make sure that the bone continues to grow normally.

- Plastic deformation of the bone, in which the bone permanently bends, but does not break, also is possible in children. These injuries may require an osteotomy (bone cut) to realign the bone if it is fixed and cannot be realigned by closed methods.

- Certain fractures mainly occur in children, including fracture of the clavicle and supracondylar fracture of the humerus.

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.

Monteggia fractures may be managed conservatively in children with closed reduction (resetting and casting), but due to high risk of displacement causing malunion, open reduction internal fixation is typically performed.

Osteosynthesis (open reduction and internal fixation) of the ulnar shaft is considered the standard of care in adults. It promotes stability of the radial head dislocation and allows very early mobilisation to prevent stiffness. The elbow joint is particularly susceptible to loss of motion.

16-40 year-old males are responsible for the majority of hip dislocations. These hip dislocations are typically posterior, and a direct result of motor vehicle traffic collisions.

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

Leri-Weill dyschondrosteosis is a pseudoautosomal dominant disorder which occurs more frequently in females and is due to a mutation, deletion or duplication of the SHOX gene. The SHOX gene plays a particularly important role in the growth and maturation of bones in the arms and legs. The SHOX gene is located within band Xp22.3 of the pseudoautosomal region of the X chromosome, which escapes X-inactivation. Homozygous SHOX gene mutations result in Langer mesomelic dysplasia.

Osteoarthritis, a common symptom associated with Canine Hip Dysplasia in German Shepherds ultimately results in pain and inflammation. The causes are from bone degradation in which the bone is less rigid, cartilage dissipates and structure of joints becomes weak.

Diet can have a major impact for German Shepherds that are exposed to Canine Hip Dysplasia. Incorporating Omega-3 fatty acids such as Docosahexaenoic acid(DHA) and Eicosapentaenoic acid(EPA) into the diet can result in improved symptoms of the disease. Omega 3 fatty acids can help decrease inflammation that occurs from osteoarthritis, as well as improvement in locomotion of dogs who have the disease. EPA and DHA can be supplemented into the diet through fish oils and in return is beneficial for reducing joint inflammation.

Glucosamine and Chondroitin sulfate are Nutraceuticals that can also be added into the diet to help treat osteoarthritis and its quality of life reducing effects. Both nutraceuticals help with improvement of cartilage, joint health and repairing of tissues. This inclusion will allow for a stronger support and reduced negative effects of osteoarthritis. Another nutrient that can help improve the structural support of the body in German Shepherds is Vitamin C. Vitamin C contributes to the building blocks of collagen that can help to strengthen the joints.

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.

Although the precise mechanism of injury is unclear, the injury occurs in children who have fallen heavily with their arm trapped under the body. In his original description of the injury, Hume suggested that the injury occurred as a result of hyperextension of the elbow leading to fracture of the olecranon, with pronation of the forearm leading to the radial head dislocation.

Smokers generally have lower bone density than non-smokers, so have a much higher risk of fractures. There also is evidence that smoking delays bone healing.