Women in sports such as association football, basketball, and tennis are significantly more prone to ACL injuries than men. The discrepancy has been attributed to gender differences in anatomy, general muscular strength, reaction time of muscle contraction and coordination, and training techniques.

Gender differences in ACL injury rates become evident when specific sports are compared. A review of NCAA data has found relative rates of injury per 1000 athlete exposures as follows:

- Men's basketball 0.07, women's basketball 0.23

- Men's lacrosse 0.12, women's lacrosse 0.17

- Men's football 0.09, women's football 0.28

The highest rate of ACL injury in women occurred in gymnastics, with a rate of injury per 1000 athlete exposures of 0.33

Of the four sports with the highest ACL injury rates, three were women's – gymnastics, basketball and soccer.

According to recent studies, female athletes are two to eight times more likely to strain their anterior cruciate ligament (ACL) in sports that involve cutting and jumping as compared to men who play the same particular sports (soccer, basketball, and volleyball). Differences between males and females identified as potential causes are the active muscular protection of the knee joint, the greater Q angle putting more medial torque on the knee joint, relative ligament laxity caused by differences in hormonal activity from estrogen and relaxin, intercondylar notch dimensions, and muscular strength.

High school athletes are at increased risk for ACL tears when compared to non-athletes. This risk increases with certain types of sports. Among high school girls, the sport with the highest risk of ACL tear is soccer, followed by basketball and lacrosse. The highest risk sport for boys was basketball, followed by lacrosse and soccer. Children and young athletes may benefit from early surgical reconstruction after ACL injury. Young athletes who have early surgical reconstruction of their torn ACL are more likely to return to their previous level of athletic ability when compared to those who underwent delayed surgery or nonoperative treatment. They are also less likely to experience instability in their knee if they undergo early surgery.

Specific populations at high risk of primary PFPS include runners, bicyclists, basketball players, young athletes and females.

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.

Isolated and combined posterolateral knee injuries are difficult to accurately diagnose in patients presenting with acute knee injuries. The incidence of isolated posterolateral corner injuries has been reported to be between 13% and 28%. Most PLC injuries accompany an ACL or PCL tear, and can contribute to ACL or PCL reconstruction graft failure if not recognized and treated. A study by LaPrade "et al." in 2007 showed the incidence of posterolateral knee injuries in patients presenting with acute knee injuries and hemarthrosis (blood in the knee joint) was 9.1%.

In 2010 national statistics was done by Agency for Healthcare Research and Quality for posterior cruciate ligaments injuries. They found that 463 patients were discharge for having some type of PCL injury. The 18- to 44-year-old age group was found to have the highest injuries reported (figure 1). One reason why this age group consists of the majority of injuries to the PCL is because people are still very active in sports at this age. Men were also reported having more injuries to the PCL (figure 3).

The condition is usually self-limiting and is caused by stress on the patellar tendon that attaches the quadriceps muscle at the front of the thigh to the tibial tuberosity. Following an adolescent growth spurt, repeated stress from contraction of the quadriceps is transmitted through the patellar tendon to the immature tibial tuberosity. This can cause multiple subacute avulsion fractures along with inflammation of the tendon, leading to excess bone growth in the tuberosity and producing a visible lump which can be very painful, especially when hit. Activities such as kneeling may also irritate the tendon.

The syndrome may develop without trauma or other apparent cause; however, some studies report up to 50% of patients relate a history of precipitating trauma. Several authors have tried to identify the actual underlying etiology and risk factors that predispose Osgood–Schlatter disease and postulated various theories. However, currently it is widely accepted that Osgood–Schlatter disease is a traction apophysitis of the proximal tibial tubercle at the insertion of the patellar tendon caused by repetitive micro-trauma. In other

words, Osgood–Schlatter disease is an overuse injury and closely related to the physical activity of the child. It was shown that children

who actively participate in sports are affected more frequently as compared with non-participants. In a retrospective study of adolescents, old athletes actively participating in sports showed a frequency of 21% reporting the syndrome compared with only 4.5% of age-matched nonathletic controls.

The symptoms usually resolve with treatment but may recur for 12–24 months before complete resolution at skeletal maturity, when the tibial epiphysis fuses. In some cases the symptoms do not resolve until the patient is fully grown. In approximately 10% of patients the symptoms continue unabated into adulthood, despite all conservative measures.

About 25% of people over the age of 50 experience knee pain from degenerative knee diseases.

OSD occurs from the combined effects of tibial tuberosity immaturity and quadriceps tightness. There is a possibility of migration of the ossicle or fragmentation in Osgood-Schlatter patients. The implications of OSD and the ossification of the tubercle can lead to functional limitations and pain for patients into adulthood.

Of people admitted with OSD, about half were children who were between the ages of 1 and 17. In addition, in 2014, a case study of 261 patients was observed over 12 to 24 months. 237 of these people responded well to sport restriction and non-steroid anti-inflammatory agents, which resulted in recovery to normal athletic activity.

In general, SCFE is caused by increased force applied across the epiphysis, or a decrease in the resistance within the physis to shearing. No single cause accounts for SCFEs, as several factors play a role in the development of a SCFE, particularly mechanical and endocrine (hormone-related) factors. Mechanical risk factors include obesity, coxa profunda, femoral or acetabular retroversion. Obesity is the most significant risk factor. In 65 percent of cases of SCFE, the person is over the 95th percentile for weight. Common misconception is heredity. Majority of cause is due to being overweight. Endocrine diseases also contribute, such as hypothyroidism, hypopituitarism, and renal osteodystrophy.

According to the posterior cruciate ligament injuries only account for 1.5 percent of all knee injuries (figure 2). If it is a single injury to the posterior cruciate ligament that requires surgery only accounted for 1.1 percent compared to all other cruciate surgeries but when there was multiple injuries to the knee the posterior cruciate ligament accounted for 1.2 percent of injuries.

In the United States, more than US $3 billion is spent each year on arthroscopic knee surgeries that are known to be ineffective in people with degenerative knee pain.

Future research into posterolateral injuries will focus on both the treatment and diagnosis of these types of injuries to improve PLC injury outcomes. Studies are needed to correlate injury patterns and mechanisms with clinical measures of knee instability and laxity.

A study containing 100 consecutive patients with a recent anterior cruciate ligament injury were examined with respect to type of sports activity that caused the injury. Of the 100 consecutive ACL injuries, there were also 53 medial collateral ligament injuries, 12 medial, 35 lateral and 11 bicompartmental meniscal lesions. 59/100 patients were injured during contact sports, 30/100 in downhill skiing and 11/100 in other recreational activities, traffic accidents or at work.

An associated medial collateral ligament tear was more common in skiing (22/30) than during contact sports (23/59), whereas a bicompartmental meniscal lesion was found more frequently in contact sports (9/59) than in skiing (0/30). Weightbearing was reported by 56/59 of the patients with contact sports injuries whereas 8/30 of those with skiing injuries. Non-weightbearing in the injury situation led to the same rate of MCL tears (18/28) as weightbearing (35/72) but significantly more intact menisci (19/28 vs 23/72). Thus, contact sports injuries were more often sustained during weightbearing, with a resultant joint compression of both femuro-tibial compartments as shown by the higher incidence of bicompartmental meniscal lesions. The classic "unhappy triad" was a rare finding (8/100) and Fridén T, Erlandsson T, Zätterström R, Lindstrand A, and Moritz U. suggest that this entity should be replaced by the "unhappy compression injury".

The meniscal tear is the most common knee injury. A meniscal tear tends to be more frequent in sports that have rough contact or pivoting sports such as soccer. The meniscal tear is more common in males than females. The ratio is about two and a half males to one female. Males between the ages of thirty-one and forty tend to tear their meniscus more frequently than younger men. Females on the other hand, seem to be more likely to tear their meniscus between the ages of eleven and twenty. People who work in straining jobs such as construction or pro athletes are also more likely to have a meniscal tear because of all the different tensions of their knees. According to the United States National Library of Medicine, the isolated medial meniscal tear occurs more frequently than any other tear associated with the meniscus. The prevalence of meniscus tears is the same for both knees. In a few different studies the BMI of a person can have a greater effect on the frequency of a meniscus tear because having a higher BMI will result in more weight on the joints which can cause the knee to be non-aligned which causes more weight on the muscles resulting in an easier tear. In 2008 the U.S Department of Health and Human Services reported a combined total of 2,295 discharges for the principal diagnosis of tear of lateral cartilage/meniscus (836.0), tear of medial cartilage/meniscus (836.1), and tear of cartilage/meniscus (836.2). Females had a total of 53.49% discharges while males had 45.72%. Individuals between the ages of 45–68 years had an average of 31.73% discharges followed by age group 65–84 with 28.82%. The average length of stay for a patient diagnosed with torn menisci was 2.7 days for males and 3.7 days for females. There was a report of 6,941 hospital discharges for knee repair. Individuals between 18–44 years of age were among the highest with 37.37% total of discharges followed by the age group 45–64 with a percentage of 36.34%. Males had a slightly higher number of discharges (50.78%) than females (48.66%). The average length of stay for both male and female patients in a hospital setting was 3.1.

It is possible to prevent the onset of prepatellar bursitis, or prevent the symptoms from worsening, by avoiding trauma to the knee or frequent kneeling. Protective knee pads can also help prevent prepatellar bursitis for those whose professions require frequent kneeling and for athletes who play contact sports, such as American football, basketball, and wrestling.

Tear of a meniscus is a common injury in many sports. The menisci hold 30–50% of the body load in standing position. Some sports where a meniscus tear is common are American football, association football, ice hockey and tennis. Regardless of what the activity is, it is important to take the correct precautions to prevent a meniscus tear from happening.

In most patients with PFPS an examination of their history will highlight a precipitating event that caused the injury. Changes in activity patterns such as excessive increases in running mileage, repetitions such as running up steps and the addition of strength exercises that affect the patellofemoral joint are commonly associated with symptom onset. Excessively worn or poorly fitted footwear may be a contributing factor. To prevent recurrence the causal behaviour should be identified and managed correctly.

The medical cause of PFPS is thought to be increased pressure on the patellofemoral joint. There are several theorized mechanisms relating to how this increased pressure occurs:

- Increased levels of physical activity

- Malalignment of the patella as it moves through the femoral groove

- Quadriceps muscle imbalance

- Tight anatomical structures, e.g. retinaculum or iliotibial band.

The cause of pain and dysfunction often results from either abnormal forces (e.g. increased pull of the lateral quadriceps retinaculum with acute or chronic lateral PF subluxation/dislocation) or prolonged repetitive compressive or shearing forces (running or jumping) on the PF joint. The result is synovial irritation and inflammation and subchondral bony changes in the distal femur or patella known as "bone bruises". Secondary causes of PF Syndrome are fractures, internal knee derangement, osteoarthritis of the knee and bony tumors in or around the knee.

Most commonly due to anterior shoulder dislocation caused by hyperabduction and external rotation of the arm. Usually in young men who play contact sports (E.g. rugby, football, volleyball, basketball, etc.). Frequent anterior (frontward) subluxation also poses a great risk factor.

It is an overuse injury from repetitive overloading of the extensor mechanism of the knee. The microtears exceed the body's healing mechanism unless the activity is stopped.

Among the risk factors for patellar tendonitis are low ankle dorsiflexion, weak gluteal muscles, and muscle tightness, particularly in the calves, quadriceps muscle, and hamstrings.

The injury occurs to athletes in many sports.

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.

A patellar dislocation is a knee injury in which the patella (kneecap) slips out of its normal position. Often the knee is partly bent, painful and swollen. The patella is also often felt and seen out of place. Complications may include a patella fracture or arthritis.

A patellar dislocation typically occurs when the knee is straight and the lower leg is bent outwards when twisting. Occasionally it occurs when the knee is bent and the patella is hit. Commonly associated sports include soccer, gymnastics, and ice hockey. Dislocations nearly always occur away from the midline. Diagnosis is typically based on symptoms and supported by X-rays.

Reduction is generally done by pushing the patella towards the midline while straightening the knee. After reduction the leg is generally splinted in a straight position for a few weeks. This is then followed by physical therapy. Surgery after a first dislocation is generally of unclear benefit. Surgery may be indicated in those who have broken off a piece of bone within the joint or in which the patella has dislocated multiple times.

Patellar dislocations occur in about 6 per 100,000 people per year. They make up about 2% of knee injuries. It is most common in those 10 to 17 years years old. Rates in males and females are similar. Recurrence after an initial dislocation occurs in about 30% of people.

Tibial plateau fractures constitute 1% of all fractures. Peak age is 30–40 years old in men and 60-70 in women. Approximately half of the people who sustain a tibial plateau fracture are aged over 50 years old.

The various nicknames associated with prepatellar bursitis arise from the fact that it commonly occurs among those individuals whose professions require frequent kneeling, such as carpenters, carpet layers, gardeners, housemaids, mechanics, miners, plumbers, and roofers. The exact incidence of the condition is not known; it is difficult to estimate because only severe septic cases require hospital admission, and mild non-septic cases generally go unreported. Prepatellar bursitis is more common among males than females. It affects all age groups, but is more likely to be septic when it occurs in children.

Humeral avulsion of the glenohumeral ligament (HAGL) is defined as an avulsion (tearing away) of the inferior glenohumeral ligament from the anatomic neck of the humerus. In other words, it occurs when we have disruption of the ligaments that join the humerus to the glenoid.

HAGL tends to occur in 7.5-9.3% of cases of anterior shoulder instability. Making it an uncommon cause of anterior shoulder instability.

Avulsion of this ligamentous complex may occur in three sites: glenoid insertion (40%), the midsubstance (35%) and the humeral insertion (25%).