Usually the result of compressive force, bone bruises occur when someone is injured through falls, accidents, sports and blows from hard objects. Bone bruises may be accompanied by bleeding and painful swelling and last from several days to months depending on the severity. Bleeding occurs under the periosteum, the tough fibrous covering of the bone. Bone bruising of the knee, or runner's knee, occurs due to stress put on the knees from excessive training and continued running on hard surfaces.
Causes
Runner's knee is common among runners but it can also occur on other athletes who perform activities that require them to do a lot of knee bending. This can irritate the nerves of the kneecap. It can also be caused by overstretched tendons due to over training. Bone bruising can occur when a runner falls on his knees, which can cause direct trauma to the knees. Other causes include misalignment of the kneecap, dislocation of the kneecap, flat feet and weak thigh muscles. Bone bruising of the knees is commonly associated with ligament and cartilage damage, particularly that of the anterior cruciate ligament.
Symptoms
Symptoms of bone bruising of the knee include pain around or behind the kneecap particularly on the top of the knee where the thighbone and the kneecap meet. You may also have runner's knee when you experience pain when running, walking, kneeling, sitting or squatting and walking or running downhill. Swelling and popping or grinding sensations in the knee when you stand, walk or run can be symptoms of a bruised bone of the knee.
Diagnosis
Your doctor will ask for your medical history and a description of your training activities. Diagnosis for runner's knee include a physical of the knee by assessing the strength of your knee, its mobility and alignment when you stand, walk, squat, sit, lie down and jump. The physical examination involves checking the alignment of the lower leg, kneecap and quadriceps. You will also be checked for knee stability, hip rotation and the range of motion of your knees and hips and to see if there is any sign of tenderness under the kneecap. Magnetic resonance imaging, a computed tomography scan or X-rays may be needed for proper diagnosis.
First Aid
First aid for runner's knee involves rest, ice, compression and elevation. Rest includes the avoidance of putting any weight on the painful knee or switching to other non-weight bearing activity. Apply ice wrapped in a towel for several minutes, several times a day on the affected area or using an elastic bandage that fits snugly, with the kneecap cut out and elevating the injured knee higher than the heart.
Medical Treatment
Your doctor may also prescribe non-steroidal pain medication. After the pain and swelling has gone down, the doctor will give you an assessment and recommend reconditioning exercises so you can regain full range of motion and rebuild your strength, endurance, coordination, speed and agility or cross-training exercises for stretching the legs before you can resume running activities. Increase the intensity and the duration of the training gradually. Severe cases of bone bruising may require surgery.
Prevention
Before you start running, perform warmup stretching exercises, paying particular attention to the front of the knee. One stretching exercise is to lay face down, bending the affected knee and grabbing the ankle to gently stretch the muscles in front of the knee. Wear running shoes with good shock absorption and good quality construction that fits your feet properly. Shoe inserts will greatly help runners with flat feet. Use proper running form, with the body leaning forward and the knees slightly bent. Try to run on clear, smooth and even surfaces that are reasonably soft. When going down a steep hill, either walk or run in a zigzag pattern rather than running straight down.
