X-ray images (normally during weightbearing) can be obtained to rule out other conditions or to see if the patient also has osteoarthritis. The menisci themselves cannot be visualised with plain radiographs. If the diagnosis is not clear from the history and examination, the menisci can be imaged with magnetic resonance imaging (an MRI scan). This technique has replaced previous arthrography, which involved injecting contrast medium into the joint space. In straightforward cases, knee arthroscopy allows quick diagnosis and simultaneous treatment. Recent clinical data shows that MRI and clinical testing are comparable in sensitivity and specificity when looking for a meniscal tear.

Magnetic resonance imaging (MRI) can be helpful in assessing for a ligamentous injury to the medial side of the knee. Milewski et al. has found that grade I to III classification can be seen on MRI. With a high-quality image (1.5 tesla or 3 tesla magnet) and no previous knowledge of the patient’s history, musculoskeletal radiologists were able to accurately diagnose medial knee injury 87% of the time. MRI can also show associated bone bruises on the lateral side of the knee, which one study shows, happen in almost half of medial knee injuries.

Knee MRIs should be avoided for knee pain without mechanical symptoms or effusion, and upon non-successful results from a functional rehabilitation program.

Anterior-posterior (AP) radiographs are useful for reliably assessing normal anatomical landmarks. Bilateral valgus stress AP images can show a difference in medial joint space gapping. It has been reported that an isolated grade III sMCL tear will show an increase in medial compartment gapping of 1.7 mm at 0° of knee flexion and 3.2 mm at 20° of knee flexion, compared to the contralateral knee. Additionally, a complete medial ligamentous disruption (sMCL, dMCL, and POL) will show increased gapping by 6.5 mm at 0° and 9.8 mm at 20° during valgus stress testing. Pellegrini-Stieda syndrome can also be seen on AP radiographs. This finding is due to calcification of the sMCL (heterotopic ossification) caused by the chronic tear of the ligament.

Laximetry is a reliable technique for diagnosing a torn anterior cruciate ligament.

The MRI is perhaps the most used technique for diagnosing the state of the Anterior Cruciate Ligament but it not always the most reliable. In some cases the Anterior Cruciate Ligament can indeed not be seen because of the blood surrounding it.

Patients can be observed standing and walking to determine patellar alignment. The Q-angle, lateral hypermobility, and J-sign are commonly used determined to determine patellar maltracking. The patellofemoral glide, tilt, and grind tests (Clarke's sign), when performed, can provide strong evidence for PFPS. Lastly, lateral instability can be assessed via the patellar apprehension test, which is deemed positive when there is pain or discomfort associated with lateral translation of the patella.

In most cases, a physician will diagnose an ulnar collateral ligament injury using a patient’s medical history and a physical examination that includes a valgus stress test. The valgus stress test is performed on both arms and a positive test is indicated by pain on the affected arm that is not present on the uninvolved side. Physicians often utilize imaging techniques such as ultrasound, x-rays and magnetic resonance imaging or arthroscopic surgery to aid with making a proper diagnosis.

The diagnosis of patellofemoral pain syndrome is made by ruling out patellar tendinitis, prepatellar bursitis, plica syndrome, Sinding-Larsen and Johansson syndrome, and Osgood–Schlatter disease.

If severe pain persists after the first 24hours it is recommended that an individual consult with a professional who can make a diagnosis and implement a treatment plan so the patient can return to everyday activities (Flegel, 2004). These are some of the tools that a professional can use to help make a full diagnosis;

Nerve conduction studies may also be used to localize nerve dysfunction ("e.g.", carpal tunnel syndrome), assess severity, and help with prognosis.

Electrodiagnosis also helps differentiate between myopathy and neuropathy.

Ultimately, the best method of imaging soft tissue is magnetic resonance imaging (MRI), though it is cost-prohibitive and carries a high false positive rate.

A grade III PCL injury with more than 10mm posterior translation when the posterior drawer examination is performed may be treated surgically. Patients that do not improve stability during physical therapy or develop an increase in pain will be recommended for surgery.

High quality MRI images (1.5 T magnet or higher ) of the knee can be extremely useful to diagnose injuries to the posterolateral corner and other major structures of the knee. While the standard coronal, sagittal and axial films are useful, thin slice (2 mm ) coronal oblique images should also be obtained when looking for PLC injuries. Coronal oblique images should include the fibular head and styloid to allow for evaluation of the FCL and popliteus tendon.

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.

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.

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.

A meniscal tear can be classified in various ways: by anatomic location, by proximity to blood supply, etc. Various tear patterns and configurations have been described. These include:

- Radial tears;

- Flap or parrot-beak tears;

- Peripheral, longitudinal tears;

- Bucket-handle tears;

- Horizontal cleavage tears; and

- Complex, degenerative tears.

These tears can then be further classified by their proximity to the meniscus blood supply, namely whether they are located in the “red-red,” “red-white,” or “white-white” zones.

The functional importance of these classifications, however, is to ultimately determine whether a meniscus is repairable. The repairability of a meniscus depends on a number of factors. These include:

- Age/strength

- Activity level

- Tear pattern

- Chronicity of the tear

- Associated injuries (anterior cruciate ligament injury)

- Healing potential

Shin splints can be diagnosed by a physician after taking a thorough history and performing a complete physical examination. The physical examination uses gentle pressure to determine whether there is tenderness over a 4–6 inch section on the lower, inside shin area. The pain has been described as a dull ache to an intense pain that increases during exercise, and some individuals experience swelling in the pain area. People who have previously had shin splints are more likely to have it again.

Vascular and neurological examinations produce normal results in patients with shin splints. Radiographies and three-phase bone scans are recommended to differentiate between shin splints and other causes of chronic leg pain. Bone scintigraphy and MRI scans can be used to differentiate between stress fractures and shin splints.

It is important to differentiate between different lower leg pain injuries, including shin splints, stress fractures, compartment syndrome, nerve entrapment, and popliteal artery entrapment syndrome. These conditions often have many overlapping symptoms which makes a final diagnosis difficult, and correct diagnosis is needed to determine the most appropriate treatment.

If shin splints are not treated properly, or if exercise is resumed too early or aggressively, shin splints can become permanent.

Segond and reverse Segond fractures are characterized by a small avulsion, or "chip", fragment of characteristic size that is best seen on plain radiography in the anterior-posterior plane. The chip of bone may be very difficult to see on the plain x-ray exam, and may be better seen on computed tomography. MRI may be useful for visualization of the associated bone marrow edema of the underlying tibial plateau on fat- saturated T2W and STIR images, as well as the associated findings of ligamentous and/or meniscal injury.

The diagnosis of a sprain relies on the medical history, including symptoms, as well as making a differential diagnosis, mainly in distinguishing it from strains or bone fractures. The Ottawa ankle rule is a simple, widely used rule to help differentiate fractures of the ankle or mid-foot from other ankle injuries that do not require x-ray radiography. It has a specificity of nearly 100%, meaning that a patient who tests negative, according to the rule almost certainly does not have an ankle fracture.

In all injuries to the tibial plateau radiographs (commonly called x-rays) are imperative. Computed tomography scans are not always necessary but are sometimes critical for evaluating degree of fracture and determining a treatment plan that would not be possible with plain radiographs. Magnetic Resonance images are the diagnositic modality of choice when meniscal, ligamentous and soft tissue injuries are suspected. CT angiography should be considered if there is alteration of the distal pulses or concern about arterial injury.

An effective rehabilitation program reduces the chances of reinjury and of other knee-related problems such as patellofemoral pain syndrome and osteoarthritis. Rehabilitation focuses on maintaining strength and range of motion to reduce pain and maintain the health of the muscles and tissues around the knee joint.

Anterior-posterior (AP) X-rays of the pelvis, AP and lateral views of the femur (knee included) are ordered for diagnosis. The size of the head of the femur is then compared across both sides of the pelvis. The affected femoral head will appear larger if the dislocation is anterior, and smaller if posterior. A CT scan may also be ordered to clarify the fracture pattern.

Diagnosis is confirmed by x-ray imaging. Displaced fractures are readily apparent. A non-displaced fracture can be difficult to identify and a fracture line may not be visible on the X-rays. However, the presence of a joint effusion is highly suggestive of a non-displaced fracture. Bleeding from the fracture expands the joint capsule and is visualized on the lateral view as a darker area anteriorly and posteriorly, and is known as the sail sign. Depending on the child's age, parts of the bone will still be developing and if not yet calcified, will not show up on the X-rays. At times, X-rays of the opposite elbow may be obtained for comparison. There are landmarks on the X-rays that can be used to assess displacement, including the "anterior humeral line", which is a line drawn down along the front of the humerus on the lateral view and it should pass through the middle third of the capitulum of the humerus.

Most people improve significantly in the first two weeks. However, some still have problems with pain and instability after one year (5–30%). Re-injury is also very common.

This condition is usually curable with appropriate treatment, or sometimes it heals spontaneously. If it is painless, there is little cause for concern.

Correcting any contributing biomechanical abnormalities and stretching tightened muscles, such as the iliopsoas muscle or iliotibial band, is the goal of treatment to prevent recurrence.

Referral to an appropriate professional for an accurate diagnosis is necessary if self treatment is not successful or the injury is interfering with normal activities. Medical treatment of the condition requires determination of the underlying pathology and tailoring therapy to the cause. The examiner may check muscle-tendon length and strength, perform joint mobility testing, and palpate the affected hip over the greater trochanter for lateral symptoms during an activity such as walking.

There are several classification schemes for ankle fractures:

- The Lauge-Hansen classification categorises fractures based on the mechanism of the injury as it relates to the position of the foot and the deforming force (most common type is supination-external rotation)

- The Danis-Weber classification categorises ankle fractures by the level of the fracture of the distal fibula (type A = below the syndesmotic ligament, type B = at its level, type C = above the ligament), with use in assessing injury to the syndesmosis and the interosseous membrane

- The Herscovici classification categorises medial malleolus fractures of the distal tibia based on level.

- The Ruedi-Allgower classification categorizes pilon fractures of the distal tibia.