People often describe pain as being “inside the knee cap.” The leg tends to flex even when relaxed. In some cases, the injured ligaments involved in patellar dislocation do not allow the leg to flex almost at all.

Posterior dislocations are uncommon, and are typically due to the muscle contraction from electric shock or seizure. They may be caused by strength imbalance of the rotator cuff muscles. Patients typically present holding their arm internally rotated and adducted, and exhibiting flattening of the anterior shoulder with a prominent coracoid process.

Posterior dislocations may go unrecognized, especially in an elderly patient and in the unconscious trauma patient. An average interval of 1 year was noted between injury and diagnosis in a series of 40 patients.

A diagnosis of shoulder dislocation is often suspected based on patient history and physical examination. Radiographs are made to confirm the diagnosis. Most dislocations are apparent on radiographs showing incongruence of the glenohumeral joint. Posterior dislocations may be hard to detect on standard AP radiographs, but are more readily detected on other views. After reduction, radiographs are usually repeated to confirm successful reduction and to detect bony damage. After repeated shoulder dislocations, an MRI scan may be used to assess soft tissue damage. In regards to recurrent dislocations, the apprehension test (anterior instability) and sulcus sign (inferior instability) are useful methods for determining predisposition to future dislocation.

There are three main types of dislocations: anterior, posterior, and inferior.

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.

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.

Many rotator cuff tears are asymptomatic. They are known to increase in frequency with age and the most common cause is age-related degeneration and, less frequently, sports injuries or trauma. Both partial and full thickness tears have been found on "post mortem" and MRI studies in those without any history of shoulder pain or symptoms. However, the most common presentation is shoulder pain or discomfort. This may occur with activity, particularly shoulder activity above the horizontal position, but may also be present at rest in bed. Pain-restricted movement above the horizontal position may be present, as well as weakness with shoulder flexion and abduction.

Symptoms may occur immediately after trauma (acute) or develop over time (chronic).

Acute injury is less frequent than chronic disease, but may follow bouts of forcefully raising the arm against resistance, as occurs in weightlifting, for example. In addition, falling forcefully on the shoulder can cause acute symptoms. These traumatic tears predominantly affect the supraspinatus tendon or the rotator interval and symptoms include severe pain that radiates through the arm, and limited range of motion, specifically during abduction of the shoulder.

Chronic tears occur among individuals who constantly participate in overhead activities, such as pitching or swimming, but can also develop from shoulder tendinitis or rotator cuff disease. Symptoms arising from chronic tears include sporadic worsening of pain, debilitation, and atrophy of the muscles, noticeable pain during rest, crackling sensations (crepitus) when moving the shoulder, and inability to move or lift the arm sufficiently, especially during abduction and flexion motions.

Pain in the anterolateral aspect of the shoulder is not specific to the shoulder, and may arise from, and be referred from, the neck, heart or gut.

Patient history will often include pain or ache over the front and outer aspect of the shoulder, pain aggravated by leaning on the elbow and pushing upwards on the shoulder (such as leaning on the armrest of a reclining chair), intolerance of overhead activity, pain at night when lying directly on the affected shoulder, pain when reaching forward (e.g. unable to lift a gallon of milk from the refrigerator). Weakness may be reported, but is often masked by pain and is usually found only through examination. With longer-standing pain, the shoulder is favored and gradually loss of motion and weakness may develop, which, due to pain and guarding, are often unrecognized by the patient and only brought to attention during examination.

Primary shoulder problems may cause pain over the deltoid muscle intensified by abduction against resistance - the impingement sign. This signifies pain arising from the rotator cuff, but cannot distinguish between inflammation, strain, or tear. Patients may report that they are unable to reach upwards to brush their hair or to lift a food can from an overhead shelf.

Subacromial bursitis often presents with a constellation of symptoms called impingement syndrome. Pain along the front and side of the shoulder is the most common symptom and may cause weakness and stiffness. If the pain resolves and weakness persists other causes should be evaluated such as a tear of the rotator cuff or a neurological problem arising from the neck or entrapment of the suprascapular nerve. The onset of pain may be sudden or gradual and may or may not be related to trauma. Night time pain, especially sleeping on the affected shoulder, is often reported. Localized redness or swelling are less common and suggest an infected subacromial bursa. Individuals affected by subacromial bursitis commonly present with concomitant shoulder problems such as arthritis, rotator cuff tendinitis, rotator cuff tears, and cervical radiculopathy (pinched nerve in neck).

Impingement may be brought on by sports activities, such as overhead throwing sports and swimming, or overhead work such as painting, carpentry, or plumbing. Activities that involve repetitive overhead activity, or directly in front, may cause shoulder pain. Direct upward pressure on the shoulder, such as leaning on an elbow, may increase pain.

Nine out of ten hip dislocations are posterior. The affected limb will be in a position of flexion, adduction, and internally rotated in this case. The knee and the foot will be in towards the middle of the body. A sciatic nerve palsy is present in 8%-20% of cases.

In an anterior dislocation the limb is held by the patient in externally rotated with mild flexion and abduction. Femoral nerve palsies can be present, but are uncommon.

As the name implies, movement of the shoulder is severely restricted in people with a "frozen shoulder". This condition, which doctors call adhesive capsulitis, is frequently caused by injury that leads to lack of use due to pain. Rheumatic disease progression and recent shoulder surgery can also cause frozen shoulder. Intermittent periods of use may cause inflammation. Adhesions (abnormal bands of tissue) grow between the joint surfaces, restricting motion. There is also a lack of synovial fluid, which normally lubricates the gap between the arm bone and socket to help the shoulder joint move. It is this restricted space between the capsule and ball of the humerus that distinguishes adhesive capsulitis from a less complicated painful, stiff shoulder. People with diabetes, stroke, lung disease, rheumatoid arthritis, and heart disease, or who have been in an accident, are at a higher risk for frozen shoulder. The condition rarely appears in people under the age of 40.

As with other types of fractures, scapular fracture may be associated with pain localized to the area of the fracture, tenderness, swelling, and crepitus (the crunching sound of bone ends grinding together). Since scapular fractures impair the motion of the shoulder, a person with a scapular fracture has a reduced ability to move the shoulder joint. Signs and symptoms may be masked by other injuries that accompany the scapular fracture.

The most common symptoms in impingement syndrome are pain, weakness and a loss of movement at the affected shoulder. The pain is often worsened by shoulder overhead movement and may occur at night, especially if the patient is lying on the affected shoulder. The onset of the pain may be acute if it is due to an injury or may be insidious if it is due to a gradual process such as an osteoarthritic spur. The pain has been described as dull rather than sharp, and lingers for long periods of a time, making it hard to fall asleep at night. Other symptoms can include a grinding or popping sensation during movement of the shoulder.

The range of motion at the shoulder may be limited by pain. A painful arc of movement may be present during forward elevation of the arm from 60° to 120°. Passive movement at the shoulder will appear painful when a downwards force is applied at the acromion but the pain will ease once the downwards force is removed.

A shoulder fracture that occurs after a major injury is usually accompanied by severe pain. Within a short time, there may be redness and bruising around the area. Sometimes a fracture is obvious because the bones appear out of position.

(However this occur in non-involved dislocations and separations.) Both diagnosis and severity can be confirmed by x rays.

Enthesopathies may take the form of spondyloarthropathies (joint diseases of the spine) such as ankylosing spondylitis, plantar fasciitis, and Achilles tendinitis. Enthesopathy can occur at the elbow, wrist, carpus, hip, knee, ankle, tarsus, or heel bone, among other regions. Further examples include:

- Adhesive capsulitis of shoulder

- Rotator cuff syndrome of shoulder and allied disorders

- Periarthritis of shoulder

- Scapulohumeral fibrositis

- Synovitis of hand or wrist

- Periarthritis of wrist

- Gluteal tendinitis

- Iliac crest spur

- Psoas tendinitis

- Trochanteric tendinitis

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%).

Pain along the inside of the elbow is the main symptom of this condition. Throwing athletes report it occurs most often during the acceleration phase of throwing. Closing the hand and clenching the fist has also been shown to reproduce the painful symptoms. The injury is often associated with an experience of a sharp “pop” in the elbow, followed by pain during a single throw. In addition, swelling and bruising of the elbow, loss of elbow range of motion, and a sudden decrease in throwing velocity are all common symptoms of a UCL injury. If the injury is less severe, pain can be minimal with complete rest.

Ulnar collateral ligament injuries can occur during certain activities such as overhead baseball pitching. Acute or chronic disruption and/or attenuation of the ulnar collateral ligament often result in medial elbow pain, valgus instability, neurologic deficiency, and impaired throwing performance. There are both non-surgical and surgical treatment options.

A sprain is a type of acute injury which results from the stretching or tearing of a ligament. Depending on the severity of the sprain, the movement on the joint can be compromised since ligaments aid in the stability and support of joints. Sprains are commonly seen in vulnerable areas such as the wrists, knees, and ankles. They can occur from movements such as falling on an outstretched hand, or a twisting of the ankle or foot.

The severity of a sprain can also be classified:

Grade 1: Only some of the fibers in the ligament are torn, and the injured site is moderately painful and swollen. Function in the joint will be unaffected for the most part.

Grade 2: Many of the ligament fibers are torn, and pain and swelling is moderate. The functionality of the joint is compromised.

Grade 3: The soft tissue is completely torn, and functionality and strength on the joint is completely compromised. In most cases, surgery is needed to repair the damage.

Shoulder impingement syndrome, also called subacromial impingement, painful arc syndrome, supraspinatus syndrome, swimmer's shoulder, and thrower's shoulder, is a clinical syndrome which occurs when the tendons of the rotator cuff muscles become irritated and inflamed as they pass through the subacromial space, the passage beneath the acromion. This can result in pain, weakness and loss of movement at the shoulder.

A strain is a type of acute injury that occurs to the muscle or tendon. Similar to sprains, it can vary in severity, from a stretching of the muscle or tendon to a complete tear of the tendon from the muscle. Some of the most common places that strains occur are in the foot, back of the leg (hamstring), or back.

One sign of a frozen shoulder is that the joint becomes so tight and stiff that it is nearly impossible to carry out simple movements, such as raising the arm. The movement that is most severely inhibited is external rotation of the shoulder.

People complain that the stiffness and pain worsen at night. Pain due to frozen shoulder is usually dull or aching. It can be worsened with attempted motion, or if bumped. A physical therapist, osteopath or chiropractor, physician, physician assistant, or nurse practitioner may suspect the patient has a frozen shoulder if a physical examination reveals limited shoulder movement. Frozen shoulder can be diagnosed if limits to the active range of motion (range of motion from active use of muscles) are the same or almost the same as the limits to the passive range of motion (range of motion from a person manipulating the arm and shoulder). An arthrogram or an MRI scan may confirm the diagnosis, though in practice this is rarely required.

The normal course of a frozen shoulder has been described as having three stages:

- Stage one: The "freezing" or painful stage, which may last from six weeks to nine months, and in which the patient has a slow onset of pain. As the pain worsens, the shoulder loses motion.

- Stage two: The "frozen" or adhesive stage is marked by a slow improvement in pain but the stiffness remains. This stage generally lasts from four to nine months.

- Stage three: The "thawing" or recovery, when shoulder motion slowly returns toward normal. This generally lasts from 5 to 26 months.

The lesion is associated with anterior or posterior shoulder dislocation. When the humerus is driven from the glenohumeral cavity, its relatively soft head impacts against the anterior edge of the glenoid. The result is a divot or flattening in the posterolateral aspect of the humeral head, usually opposite the coracoid process. The mechanism which leads to shoulder dislocation is usually traumatic but can vary, especially if there is history of previous dislocations. Sports, falls, seizures, assaults, throwing, reaching, pulling on the arm, or turning over in bed can all be causes of anterior dislocation.

Dead arm syndrome starts with repetitive motion and forces on the posterior capsule of the shoulder. The posterior capsule is a band of fibrous tissue that interconnects with tendons of the rotator cuff of the shoulder. Four muscles and their tendons make up the rotator cuff. They cover the outside of the shoulder to hold, protect and move the joint.

Overuse can lead to a buildup of tissue around the posterior capsule called hypertrophy. The next step is tightness of the posterior capsule called posterior capsular contracture. This type of problem reduces the amount the shoulder can rotate inwardly.

Over time, with enough force, a tear may develop in the labrum. The labrum is a rim of cartilage around the shoulder socket to help hold the head of the humerus (upper arm) in the joint. This condition is called a superior labrum anterior posterior (SLAP) lesion. The final outcome in all these steps is the dead arm phenomenon.

The shoulder is unstable and dislocation may come next. Dead arm syndrome will not go away on its own with rest—it must be treated. If there is a SLAP lesion, then surgery is needed to repair the problem. If the injury is caught before a SLAP tear, then physical therapy with stretching and exercise can restore it.

It is common among baseball pitchers as they age, and it can also occur with quarterbacks in football and handball players also as they age.

Subacromial bursitis is a condition caused by inflammation of the bursa that separates the superior surface of the supraspinatus tendon (one of the four tendons of the rotator cuff) from the overlying coraco-acromial ligament, acromion, coracoid (the acromial arch) and from the deep surface of the deltoid muscle. The subacromial bursa helps the motion of the supraspinatus tendon of the rotator cuff in activities such as overhead work.

Musculoskeletal complaints are one of the most common reasons for primary care office visits, and rotator cuff disorders are the most common source of shoulder pain.

Primary inflammation of the subacromial bursa is relatively rare and may arise from autoimmune inflammatory conditions such as rheumatoid arthritis; crystal deposition disorders such as gout or pseudogout; calcific loose bodies, and infection. More commonly, subacromial bursitis arises as a result of complex factors, thought to cause shoulder impingement symptoms. These factors are broadly classified as intrinsic (intratendinous) or extrinsic (extratendinous). They are further divided into primary or secondary causes of impingement. Secondary causes are thought to be part of another process such as shoulder instability or nerve injury.

In 1983 Neer described three stages of impingement syndrome. He noted that "the symptoms and physical signs in all three stages of impingement are almost identical, including the 'impingement sign'..., arc of pain, crepitus, and varying weakness." The Neer classification did not distinguish between partial-thickness and full-thickness rotator cuff tears in stage III. This has led to some controversy about the ability of physical examination tests to accurately diagnose between bursitis, impingement, impingement with or without rotator cuff tear and impingement with partial versus complete tears.

In 2005, Park et al. published their findings which concluded that a combination of clinical tests were more useful than a single physical examination test. For the diagnosis of impingement disease, the best combination of tests were "any degree (of) a positive Hawkins-Kennedy test, a positive painful arc sign, and weakness in external rotation with the arm at the side," to diagnose a full thickness rotator cuff tear, the best combination of tests, when all three are positive, were the painful arc, the drop-arm sign, and weakness in external rotation.