What Can Cause Pain In The Back Of The Knee?
A strong knee enables you to perform various activities with ease. However, you may sometime experience continuous pain in and around the knee joint. Frequently in few patients, knee joint pain may be predominantly located over back of the knee. Such back of the knee pain is known as posterior knee pain. There are several diseases that causes pain in the back of the knee. Diagnosis of cause of the pain that is felt over the back of the knee is necessary to initiate treatment. Diagnosis depends on finding of clinical examination and positive finding of investigations. The favorable outcome of timely treatment depends on correct diagnosis. Once the pain is gone or reduced to tolerable level then one must consider physical therapy and rehabilitation treatment to improve joint movement.
What Can Cause Pain Over Back Of The Knee: Posterior Knee Pain?
Causes of Pain Over Back Of The Knee Can Be Due To-
Knee Joint Injury
- Bone trauma
- Tendon injuries
- Ligament injuries
Knee Joint Inflammation
- Baker’s cyst
- Intraarticular knee joint cyst
- Popliteal artery aneurysm
Knee joint is a synovial joint also known as hinge joint. The joint surface is covered by synovial membrane. The knee joint moves 900 like a door hinge, thus joint is recognized as hinge joint. The joint is formed between thigh bone and leg bones. The thigh bone is femur bone that lies on upper or cephalic side and leg bones are tibia as well as fibula that lies on lower side. The front of joint is supported by oval shaped bone known as patella. The patella, tendons and ligaments that covers patella supports knee joint. Thus, knee joint is supported by muscles, ligaments and tendons that lies around the joint. The supporting tissue like muscle, tendon and ligament stabilizes the knee joint and facilitate knee movements. The cartilage between the joint acts as a cushion and prevents friction, shock or any damage to the joint surface of femur, tibia and fibula bone. Any damage to the structures around knee joint like bone, cartilage, ligament, muscles and tendon causes knee joint pain and discomfort. It is important and necessary to understand the cause of knee joint pain, so one can treat the cause of pain. You should consult physician earlier than later to prevent permanent damage to tissue forming knee joint.
Knee Joint Injury As A Cause For Pain In the Back of the Knee
Knee joint is used more than most other joints in human body. The published data suggests knee joint is one of the frequently injured joint.1 The reason knee joint is injured more frequently than other joint is because knee joint is weight bearing joint. Weight transmission is depended on stability of the joint and posture at the time of weight transmission. Wrong position or twist and turn can change direction of weight transmission that can result in joint injury. Knee joint injury damages structures of knee joint that is formed by bone, cartilage, ligaments, muscles and tendon.
Knee Joint Bone Trauma As A Cause For Posterior Knee Joint Pain
Knee joint is formed by femur bone at the top, tibia and fibula at the bottom, and patella in front of knee joint. The knee joint is prone to get injured during domestic fall, automobile accident, work trauma and sport injury. Forceful impact of lower leg from any direction causes severe injury of knee joint. Such injury can cause fracture of patella, femur, tibia and fibula resulting in pain over front and back side of knee. Injury such as fracture of femur, tibia, fibula and knee joint dislocation causes intense severe pain spread over back of the knee joint. Knee joint injury may also involve nerve and blood vessel injuries. Blood vessel tear causes bleeding and hematoma resulting in swelling over the back of knee joint and stabbing pain. Similarly, fracture and dislocation of knee joint may cause laceration or tear of nerves that lies in posterior popliteal fossa of knee joint.
Tendon and Muscle Injuries Resulting in Pain in the Back of the Knee
Knee joint is supported by several muscles and tendons. The flexor muscles end in tendon and then tendon is attached to the bone at the back of knee joint. Injury of following muscle or tendon causes pain that is localized over back of knee joint. The tendons of muscles of back of the thigh and lower leg is attached to the back of knee joint. These muscle are known as knee joint flexor or hamstring muscles. Injury to these muscles can occur during knee bending or upper body rotation and turning.
- Plantaris and
Ligament Injuries: Causes Pain Over Back Of The Knee
Injuries to the soft tissues that lies in posterior section of knee joint causes ligament injuries. Injuries of ligaments that support posterior section of knee joint cause severe pain that spreads over back of knee joint. The sudden severe jolting pain is felt following laceration or tear of knee joint ligaments. There are following 4 main strong ligaments that stabilizes link between femur and tibia within knee joint. In the back of the knee, there are 4 cruciate ligaments (PCL). The posterior cruciate ligament (PCL) can get injured during sports activities and accidental impact by moving when the knee is hit in a bent position. Overstretching of knee ligaments while playing sport or domestic fall causes knee joint ligament sprain or complete ligament rupture that results in severe pain. There are several other small ligaments attached to femur, tibia and fibula bone on posterior side. These ligaments firmly holds the adjacent bones together and prevents separation. Injuries like laceration or tear of ligament causes severe pain at rest and during movement of knee joint.
The following four ligament lie within knee joint-
- Medial collateral ligament (MCL),
- Lateral collateral ligament (LCL),
- Anterior cruciate ligament (ACL) and
- Posterior cruciate ligament (PCL)
Meniscus Tear Can Cause Posterior Knee Join Pain
Another common injury causing back of the knee pain is the meniscus tear. Pair of meniscus is a cartilage that lies within the knee joint and acts as a cushion. C- shaped cartilage lies between medial and lateral condyle of tibia and femur. Meniscus injuries occur with sudden twisting, forceful knee movements or overstraining a previously injured cartilage. When the posterior part of either side gets injured or damaged, it can cause pain in the back of the knee with swelling and inability to bend the knee.
Knee Joint Inflammation
Pain in the Back of the Knee Caused Due to Knee Joint Tendonitis
The over stretching of knee joint during exercise or repeated knee bending causes inflammation of knee joint tendon. Tendinitis is an inflammation of tendon in absence of laceration and tear. Repeated knee bending frequently causes inflammation of tendon of muscles that support knee joint. Tendinitis of knee joint is observed in individual running or cycling for long distance. Tendonitis is a very painful condition. Inflammation of tendon that lies over the back of the knee joint causes severe pain.
Pain in the Back of the Knee Caused Due to Knee Rheumatoid Arthritis
Rheumatoid arthritis causes inflammation of synovial membrane, capsule and knee joint cartilages. Pain and tenderness restricts the joint movement and ambulation. Knee joint pain is common in patient suffering with rheumatoid arthritis.
Osteoarthritis is a degenerative joint disease. Osteoarthritis causes degeneration of cartilages, joint capsule and ligaments. The pain caused by inflammatory joint disease restrict the joint movement. Pain intensity is often severe on lateral side and back of the knee joint.
Knee Joint Gout Resulting in Pain in the Back of the Knee
Gout is an inflammatory joint disease. Inflammation is trigger by uric acid deposits in the joint. Symptoms are sudden and causes intense pain. Joint is swollen, red and tender. Most pain is spread over back of the knee joint.
Cyst (Ganglion) Inflammation That Can Cause Pain in the Back of the Knee Joint
Intraarticular (inside the joint) cyst or ganglion are sac of diameter or length from ½ cm to 2 cm. The sac is filled with jelly like substance. Ganglion lies between ligament and bone or tendon and bone. Ganglion prevents friction between adjacent tissue and also functions as shock absorber.
Intraarticular Knee Joint Cyst:
There are several tiny ganglions located between intraarticular ligament and femur, tibia or fibula. Similarly, few ganglions or cysts protect friction between tendon and adjacent bone in knee joint.3 Inflammation of any one of these ganglion cyst causes severe pain over the back of the knee joint.
Baker’s cyst is a sac located over popliteal fossa or back of knee joint and cyst is also known as Baker’s ganglion. Inflammation of Baker’s cyst causes swelling that protrudes over back of knee joint. The swelling is tender (painful) and soft. Soft painful bulge (swelling) fluctuate during examination. Baker cyst or ganglion is the enlarged popliteal bursa that causes pain during flexion and extension of knee joint. Inflammation of bursa causes pain and increases bulge or swelling. Inflammation due to injury or arthritis causes excess fluid and inflamed jelly collection within bursa. The inflammation causes excessive secretion of prostaglandin. Prostaglandin irritates the sensory nerves and surrounding tissue that causes moderate to severe pain. Pain is observed over back of knee joint.
Muscle Spasm As A Cause For Pain In The Back of the Knee Joint
The spasm of muscles that support posterior knee joint often causes referred pain over back of the knee joint. The muscle spasm of Semitendinosus, Semimembranous, Gastrocnemius and Plantaris muscle causes spread of pain along the muscle as well as back of the knee. Popliteal muscle spasm causes severe pain over back of knee and also firm swelling of contracting muscle that is located over back of the knee.
Thrombosis of Popliteal Blood Vessels Causing Pain Over Back Of The Knee Joint –
Knee joint receives blood delivered by several arteries5 and simultaneously blood is taken away by several veins. Blood clot (thrombosis) within artery or vein causes severe pain over the back of the knee. Thrombosis is a condition caused by collection of blood clot within artery or veins. Thrombosis blocks flow of blood. The blood flow is partially or completely blocked.
Popliteal Artery Aneurysm As A Cause For Posterior Knee Joint Pain
Aneurysm is a pulsatile sac or swelling observed over wall of artery. The cyst formed on arterial wall become weak and allows weak wall to expand as a cyst. The aneurysm of Popliteal artery is observed mostly in male (95% ) and in 55% cases the aneurysm is bilateral.6 Popliteal artery aneurysm causes pulsatile swelling and pain over the back of knee.
Risk Factors For Pain In The Back Of The Knee
Following are the risk factors that may trigger pain in the back of the knee
- Excessive strain on knee
- Leg or feet deformities like flat feet
- Improper conditioning
- Inadequate muscle strength or flexibility and
Treatment For Pain In The Back Of The Knee Or Posterior Knee Pain
Treatment for pain in the back of the knee or posterior part of the knee depends on intensity of pain and various cases that has resulted in acute or chronic pain.
Conservative Treatment Posterior Knee Joint Pain- Injuries causing back of the knee pain are generally treated with the following conservative treatment:
- Cold Therapy
- Heat Compression,
- Leg Elevation (R.I.C.E. formula) and
- Use of braces or cast
Medications for Posterior Knee Joint Pain-
- Non-steroidal anti-inflammatory medications (NSAIDs)- Motrin, Naproxen and Celebrex prescribed for pain in the back of the knee caused by inflammatory diseases and mild to moderate pain.
- Tylenol- Prescribed for mild to moderate pain.
- Opioids- Hydrocodone, oxycodone and morphine prescribed for moderate to severe pain. Prescription discontinued after 2 to 3 weeks, since most long term opioid treatment causes dependence and addiction to opioids.
- Antibiotics- Antibiotics are prescribed if back of the knee pain is caused by infection.
Physical Therapy for Posterior Knee Joint Pain- Physical therapy is beneficial once the pain intensity is tolerable. Leg muscle atrophy and weakness is observed when knee joint pain is treated with rest for several days. Few cases are treated with application of cast or braces over knee joint that results in loss of muscle mass. Such cases are treated with aggressive physician therapy. Physical therapy helps to rebuild tone, power and coordination of muscle.
Surgery for Posterior Knee Joint Pain- Surgery is necessary if posterior knee joint pain is caused by fracture or dislocation of knee joint. Surgery may involve instrumentation or close reduction of fracture and dislocation.
Exercises For Pain In Back Of Knee Or Posterior Knee Pain
Physiotherapy and specific exercises monitored by physical therapist need to be initiated in order to regain free movements of the knee and prevent further damage. Lower leg exercise and knee joint stretching prevents knee joint injury in athlete who are participating in competition and professional contact sport. Following are the basic stretching and strengthening exercises for the hamstring and calf muscles. These excercises and stretching can help to keep the knee joint strong and prevent injuries.
Supine Heel Slide Exercise For Pain In Back Of Knee Or Posterior Knee Pain:
Lie on the back with legs straight; move the toes front and back to feel the stretch in calf muscles. Then slide the heels to raise the knees till they bend and touch the heels close to the body.
Prone Knee Bend Exercise For Pain In Back Of Knee Or Posterior Knee Pain:
Lie on stomach with legs straight; bend knees towards the body, hold and straighten them again.
Standing Knee Bend Exercise For Pain In Back Of Knee Or Posterior Knee Pain:
Stand and lift your leg from behind to bend the knees, hold the ankles and touch heels to the buttocks. Hold for few seconds and release. Weight can be used here too. It is advisable to follow an expert's advice.
The acute swollen knee: diagnosis and management
Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I
A case of intra-articular ganglion cysts of the knee joint: correlation between arthroscopic and magnetic resonance imaging
Baker’s Cyst Diagnostic and Surgical Considerations
Blood supply of the knee joint. A microangiographic study in children and adults.
Popliteal artery aneurysms: a review.