Differential Diagnosis for Lateral Blow to the Knee with Full Knee Replacement One Year Post-Surgery
- Single Most Likely Diagnosis
- Periprosthetic fracture: This is the most likely diagnosis due to the mechanism of injury (lateral blow to the knee) and the presence of a full knee replacement. The force of the blow can cause a fracture around the prosthetic components.
- Other Likely Diagnoses
- Ligamentous injury (e.g., medial collateral ligament sprain): The lateral blow can cause a valgus stress, leading to injury of the medial ligaments.
- Prosthetic loosening or dislocation: Trauma to the knee can cause the prosthetic components to become loose or dislocated, especially if the surrounding bone or soft tissues are weakened.
- Meniscal or cartilage injury: Although the menisci may have been removed or damaged during the knee replacement surgery, any remaining meniscal tissue or cartilage can still be injured from the trauma.
- Do Not Miss Diagnoses
- Infection: Although less likely, infection is a serious complication that can occur after trauma to a prosthetic joint. It is essential to consider this diagnosis, especially if there are signs of infection such as fever, redness, or swelling.
- Neurovascular injury: The lateral blow can cause injury to the surrounding nerves or blood vessels, which can lead to serious complications if not promptly addressed.
- Extensor mechanism disruption: The quadriceps tendon or patellar tendon can be injured from the trauma, leading to extensor mechanism disruption and significant functional impairment.
- Rare Diagnoses
- Periprosthetic osteolysis: This is a rare condition where the bone around the prosthetic components is resorbed, leading to loosening of the implant. Although rare, it can be a cause of pain and instability after trauma.
- Heterotopic ossification: This is a condition where bone forms in soft tissues, which can occur after trauma to a prosthetic joint. It is rare but can cause significant stiffness and limited mobility.