Knee fracture refers to fractures of any of the parts of bone involved in the joint itself. This includes fractures of:
1. Patella:
accounts for 1% of all fractures, most common in ages 20-50
2. Femoral condyles:
these usually fracture when the knee is stressed.
3. Tibial eminence:
caused by accidents, such as a blow to the proximal tibia when the knee is flexed, or if the knee is hyperextended during an accident. Usually seen in patients aged 8-14.
4. Tibial tuberosity:
more common in men than in women, and in younger patients rather than adults; often seen in athletes, especially those involved in jumping sports.
5. Tibial plateau:
compressive fractures of the articular surface, typically from extreme force such as fall from a height or being hit by a vehicle, although in patients with osteoporosis minimal force may be needed.
6. Segond's fracture:
this is an avulsion fracture of the lateral tibial condyle immediately beyond the articular surface with the knee. Although not directly a part of the knee joint, it occurs in association with tears of the anterior cruciate ligament (ACL), medial meniscus and lateral capsular ligament, and is thus included here.
Knee fracture can result in neurovascular compromise or compartment syndrome. Soft tissue infection or osteomyelitis may occur with open fractures. Other complications include non-union, delayed union, osteoarthritis, avascular necrosis, fat embolism, and thrombophlebitis.
Fractures around the knee are common in children, but the pattern of knee fractures differs. The relatively high proportion of cartilage in growing children may make diagnosis difficult, especially on plain X-ray, and stress radiographs or MRI may be necessary.