Differential Diagnosis
- The patient's symptoms of loss of range of motion, difficulty bending the knee, swelling, and stiffness suggest a knee injury. The absence of direct trauma to the knee and the lack of locking or giving out help to narrow down the possible diagnoses.
Single Most Likely Diagnosis
- Knee Effusion or Hemarthrosis: This is the most likely diagnosis given the patient's symptoms of swelling, stiffness, and difficulty bending the knee. The knee effusion or hemarthrosis could be caused by a ligamentous or meniscal injury, even without direct trauma to the knee.
Other Likely Diagnoses
- Ligamentous Sprain: A ligamentous sprain, such as a medial or lateral collateral ligament sprain, could cause the patient's symptoms, especially if the injury was caused by a twisting or bending motion.
- Meniscal Tear: A meniscal tear could also cause the patient's symptoms, especially if the tear is causing inflammation and swelling in the knee.
- Knee Contusion: A knee contusion, or bruising of the soft tissues around the knee, could cause the patient's symptoms, especially if the contusion is causing inflammation and swelling.
Do Not Miss Diagnoses
- Fracture: Although the patient did not experience direct trauma to the knee, it is still possible that a fracture occurred, especially if the patient experienced a severe twisting or bending motion. A fracture could be deadly if missed, as it could lead to further complications such as osteoporathing or nerve damage.
- Septic Arthritis: Septic arthritis is a serious infection that could cause the patient's symptoms, especially if the patient has a compromised immune system or has recently traveled to an area with a high risk of infection.
- Tumor or Cyst: A tumor or cyst, such as a synovial sarcoma or a Baker's cyst, could cause the patient's symptoms, especially if the tumor or cyst is causing inflammation and swelling in the knee.
Rare Diagnoses
- Osteonecrosis: Osteonecrosis, or avascular necrosis, is a rare condition that could cause the patient's symptoms, especially if the patient has a history of steroid use or has recently experienced a severe injury.
- Neurogenic Causes: Neurogenic causes, such as a peripheral nerve injury or a spinal cord injury, could cause the patient's symptoms, especially if the patient has a history of neurological disorders or has recently experienced a severe injury.
- Vascular Causes: Vascular causes, such as a deep vein thrombosis or a vascular malformation, could cause the patient's symptoms, especially if the patient has a history of vascular disorders or has recently experienced a severe injury.