Knee pain resident survival guide
Synonyms and keywords: Approach to knee stiffness, Approach to knee swelling, Approach to the hot knee joint

# Overview
The knee joint has the largest articular space. The knee joint supports two to five times a person's body weight depending on the physical activity. There are both traumatic and non-traumatic conditions that cause knee pain. Lifestyle modification for knee pain includes Rest, Ice, Compression, and Elevation (RICE) for ligament injuries, Exercise, heat treatment, Paracetamol, symptomatic slow-acting drugs for OA (glucosamine, chondroitin, diacerein, and avocadosoya unsaponifiables), Restorative sleep advice and Weight loss. Knee pain should be treated depending on the underlying cause.

# Causes

## Common Causes

## Traumatic and activity-related causes of knee pain

## Non-Traumatic causes of knee pain

# Diagnosis
The approach to the diagnosis of knee pain is based on a step-wise testing strategy. Below is an algorithm summarizing the identification and laboratory diagnosis of knee pain.

# Treatment

# Do's
- US is an excellent and easily performed imaging study in the detection of knee joint effusions. However, because of its technical limitations, ultrasound (US) may only evaluate the outer bone surface and has a limited role in the detection of occult knee fractures.
- In patients with chronic knee pain, referred pain from the hip must be considered, especially if the knee radiographs are unremarkable and there is clinical evidence or concern for hip pathology.
- When an intra-articular abnormality is suspected, CT arthrography may be used instead of MRI to evaluate the menisci and articular cartilage.
- When initial radiographs are normal or reveal a joint effusion but pain persists, the next indicated study is usually MRI without IV contrast, which is more sensitive than radiography.
- Ultrasound (US) is not often useful as a screening test or a comprehensive examination. It may be appropriate to confirm a suspected effusion and to guide a potential aspiration. The US is as accurate in diagnosing a popliteal cyst and detecting cyst rupture when compared to MRI.
- Radiographs of the knee are usually appropriate for the initial imaging of chronic knee pain in patients greater than or equal to 5 years of age.
- Knee radiographs may be appropriate for the initial imaging of patients 5 years of age or older for the evaluation of a fall or acute twisting trauma to the knee when there is no focal tenderness, no effusion, and they are able to walk.
- Knee radiographs are usually appropriate as the initial imaging study of patients 5 years of age or older for the evaluation of a fall or acute twisting trauma to the knee when at least one of the following is present: focal tenderness, effusion, inability to bear weight.
- MRI knee without IV contrast is usually appropriate as the next imaging study, after radiographs did not show a fracture, of adults or skeletally mature children, for the evaluation of suspected occult knee fractures or internal derangement after a fall or acute twisting trauma to the knee.
- MRI knee without IV contrast is usually appropriate as the next imaging study after radiographs did not show a fracture, of skeletally immature children, for the evaluation of suspected occult knee fractures or internal derangement after a fall or acute twisting trauma to the knee. 

# Don'ts
- With negative radiographs, MR arthrography is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement.
- With negative radiographs, MRA is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement.
- Ultrasound (US) is not used as the next best imaging study to evaluate for radiographically occult fractures and/or internal derangement.
- Radionuclide bone scan is usually not indicated to evaluate patients with signs of a prior (chronic) osseous knee injury.
- Joint aspiration is usually not indicated to evaluate patients with signs of the prior (chronic) osseous knee injury.