Generality
Pain behind the knee is a symptom related to various conditions.
Among the causes of pain behind the knee, in fact, there are: tendinopathy of the ischio-crural muscles, Baker's cyst, tendinopathy of the gastrocnemius muscle, "tennis leg", injuries to the posterolateral corner of the knee, injuries to the posterior cruciate ligament, deep venous thrombosis, lesions of the posterior "horns" of the meniscuses and tendinopathy of the popliteal muscle.
Short anatomical reference of the knee
The knee is the important synovial joint of the human body, placed between the femur (superiorly), tibia (inferiorly) and patella (anteriorly).
Its anatomy is quite complex and includes:
- The articular cartilage, which covers the lower surface of the femur, the inner side of the patella and the center of the upper surface of the tibia, protecting all these bones from mutual rubbing;
- The synovial membrane, which covers the joint from the inside and produces synovial fluid, a fluid with a lubricating action for all the internal structures of the knee;
- The collateral ligaments, the cruciate ligaments and the patellar tendon, which, all together, guarantee the stability of the joint and the right alignment between the femur and tibia;
- The synovial bags, which are small synovial membrane pockets, filled with a lubricating liquid very similar to the synovial fluid;
- The inner meniscus (or medial meniscus ) and the external meniscus (or lateral meniscus ), which are cartilage cushions with shock absorbing and anti-rubbing function, located on the sides of the upper surface of the tibia.
What is pain behind the knee?
" Pain behind the knee " is the expression that indicates the painful sensation felt on the back of the knee ; in other words, it is the way to define the pain suffered in the anatomical area between the back of the thigh, above, and the calf, below.
Pain Behind the Knee in medical language
In anatomy, the posterior part of the knee is called the popliteal cavity or popliteal fossa .
Consequently, wanting to give a more specialized definition to the pain behind the knee, this is the pain located in the popliteal cavity .
A bit of anatomy: the popliteal cavity
The popliteal cavity is the region of the lower limb located behind the knee, bounded by the hamstring hamstring muscles, semitendinosus and semimembranosus, above, and by the gastrocnemius muscle, below.
Closed on the surface (before the skin) by the so - called popliteal fascia (continuation of the fascia lata ), the popliteal cavity houses several lymph nodes (popliteal lymph nodes) and is a passageway for important blood vessels (popliteal vessels) and nerves (branches of the sciatic nerve known as tibial nerve and common peroneal nerve).
In its deepest parts, the popliteal cavity presents as limit the popliteal face of the femur, the popliteal muscle and the posterior surface of the articular capsule of the knee .
What Medical Figure Does Pain Behind the Knee?
The causes of pain behind the knee is a matter for orthopedic doctors, or doctors specialized in the diagnosis, treatment and prevention of diseases that can affect the musculoskeletal system.
Who suffers the most from pain behind the knee?
Pain behind the knee is a disorder that people of all ages can suffer from, but it has a higher incidence among adults and the elderly .
In general, people who develop pain most often behind the knee are athletes and individuals with a particularly active life, as they are more at risk of injuring their knees.
How widespread is the pain behind the knee?
Pain behind the knee is not very common, especially when compared with other types of joint pain, such as internal knee pain, external knee pain or anterior knee pain .
Causes
Pain behind the knee is a symptom that can depend on many different causes.
The most common causes of pain behind the knee include:
- The tendinopathy of the ischio-crural muscles ;
- Baker's cyst ;
- Gastrocnemius muscle tendinopathy ;
- The so-called tennis player's leg ;
- Injuries at the posterolateral corner of the knee .
Among the less common causes of pain behind the knee, however, are:
- Injuries to the posterior cruciate ligament ;
- Deep venous thrombosis ;
- The lesion of the posterior "horns" of one or both menisci ;
- Tendinopathy of the popliteal muscle .
Tendinopathy of the ischio-crural muscles
The ischio-crural muscles are the three muscles of the posterior part of the thigh that present the particularity to originate all of them from the so-called ischial tuberosity, situated on the ischio (a bone of the pelvis).
Known as biceps femoris, semitendinosus and semimembranosus, these muscles end, in spite of a common origin, at different points of the proximal end of the tibia and fibula.
Known as ischio-crural syndrome or hamstring syndrome, tendinopathy of the ischio-crural muscles is the suffering of one or more of the terminal tendon insertions of the biceps femoris, semitendinosus and semimembranosus muscles. The terminal tendons of the aforementioned muscles, in fact, reside and engage in portions of the tibia and fibula very close to the posterior part of the knee.
The tendinopathy of the ischio-crural muscles includes both inflammatory and degenerative conditions, and can result from lacerative processes or functional overload (eg: excess of physical activity with the lower limbs).
Baker cysts
Also known as popliteal cyst, Baker's cyst is an abnormal protuberance, similar to a nodule, which typically forms behind the knee due to the exit from the popliteal bursa (one of the synovial bags of the knee) of the synovial fluid present in it.
In most cases, Baker's cyst is the result of traumatic damage to the knee joint or a process of arthrosis ( gonarthrosis ); more rarely, Baker's cyst appears without a precise reason and in conditions of perfect health on the part of the knee.
Gastrocnemius muscle tendinopathy
The gastrocnemius muscle, or twins, is one of the two main muscles (the other is the soleus ) of the posterior part of the leg (that is, the part of the lower limb running from the knee to the foot).
The gastrocnemius muscle is formed by two elements, called the medial head and the lateral head, which have a different point of origin (the medial head from the medial condyle of the femur and the lateral head from the lateral condyle of the femur) but equal terminal insertion (the tendon of Achilles that is inserted on the heel).
The gastrocnemius muscle tendinopathy is the suffering of the tendon that hooks the medial head or the lateral head to the femur; its correlation to pain behind the knee depends on the relationship of proximity between the back of the knee and the area of origin of the gastrocnemius muscle.
Like the tendinopathy of the ischio-crural muscles, the gastrocnemius muscle tendinopathy includes both inflammatory and degenerative conditions, and can result from lacerative processes or functional overload (eg: excess of physical activity with the lower limbs).
Did you know that ...
When it concerns the medial head, the gastrocnemius muscle tendinopathy is called medial tendinopathy of the gastrocnemius; when it affects the lateral head, it is called lateral tendinopathy of the gastrocnemius.
"Tennis Player Leg"
"Tennis player's leg" is the slang expression indicating the tear or laceration of the tendon from which the plantar muscle originates, that is the muscle that runs from the lateral supracondylar ridge to the calcaneus.
The "tennis player's leg" causes pain behind the knee, because the injured tendon engages in a point of the femur very close to the posterior surface of the knee joint capsule.
Injuries at the posterolateral corner of the knee
Known as PAPE, the posterolateral corner of the knee is a specific region of this articulation, which includes: the lateral collateral ligament, the poplite-fibular ligament, the tendon of the popliteal muscle, the tendon of the biceps femoris muscle, the common peroneal nerve, the patello-femoral ligament, the lateral patellar retinaculum and the posterior horn of the lateral meniscus.
With the expression "injuries to the posterolateral corner of the knee" the doctors intend all those sufferings borne by one or more structures of the PAPE.
Injuries at the posterolateral corner of the knee cause pain behind the knee, since the structures of the PAPE all have a relationship with the posterior portion of the knee.
Less common causes of pain behind the knee
- Injuries (stretching or tearing) of the posterior cruciate ligament: the posterior cruciate ligament is one of the two ligaments of the knee joint that run from the lower surface of the distal end of the femur to the upper surface of the proximal end of the tibia (the other of these ligaments is the most "famous" anterior cruciate ligament).
- Deep vein thrombosis: it is the serious pathological process that leads to the formation of a blood clot inside a vein and from which very dangerous embolic phenomena can arise, because they are potentially fatal.
- The lesion of the posterior "horns" of one or both menisci: the posterior "horns" of the medial meniscus and of the lateral meniscus are the posterior portions of these fundamental cartilage pads.
- The tendonopathy of the popliteal muscle: it is the suffering of the tendon from which the popliteal muscle originates and which finds insertion on the lateral epicondyle of the femur, therefore extremely close to the popliteal cavity.
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Symptoms and Complications
Depending on the cause, the pain behind the knee can be more or less intense and worsen significantly or not at all during flexion of the lower limb.
If intense and / or worsens with flexion of the lower limb, pain behind the knee may be severely debilitating for the patient.
Symptoms Associated with Pain Behind the Knee
Pain behind the knee rarely occurs alone; in fact, in most cases it is associated with other symptoms, which vary according to the causal factor.
Symptoms that may be associated with pain behind the knee include:
- Joint stiffness;
- Swelling in the posterior area of the knee (NB: typical of the Baker cyst);
- Unstable knee;
- Reduced knee mobility;
- Sense of soreness slightly higher or slightly lower than the knee (NB: the soreness accompanies the cases of pain behind the knee due to a tendinopathy);
- Cracking or crackling emission from the knee, with each movement of the joint;
- Atrophy of the muscles of the suffering lower limb.
Complications
If the treatment of the triggering cause is inappropriate, the pain behind the knee is likely to become increasingly intense and debilitating or even to assume the characteristics of a chronic disorder.
A highly debilitating or chronic pain behind the knee is an obstacle to carrying out the most banal daily activities (eg climbing stairs, entering or leaving the car, etc.).
When should I go to the doctor?
Pain behind the knee is a symptom that should worry and induce the person concerned to consult a doctor when:
- It has been running for several days;
- Despite the rest and the application of ice, it persists and shows no signs of improvement;
- It is the result of a strong knee injury;
- It is associated with several other symptoms.
Diagnosis
When talking about the diagnosis of pain behind the knee, the object of discussion is clearly the identification of the triggering cause, that is the origin of the pain sensation.
Except for the clinically less severe cases (for which it is not always necessary to consult a doctor), research to establish the reasons for a worrying pain behind the knee begins with an inquiry into the associated symptoms and an accurate physical examination ; therefore, they continue with a thorough medical history ; finally, they end with imaging, to be precise with knee magnetic resonance .
Therapy
In the presence of a pain behind the knee, it is customary to resort to a conservative therapy, based on rest, application of ice on the painful area, intake of anti - inflammatories, elevation of the lower limb suffering and compression of the joint, and wait for the results of such treatments.
If the response to the aforementioned conservative therapy is positive (ie the patient benefits from rest, the application of ice, etc.), there is no need to add anything else, except to continue with the treatments until otherwise instructed by the attending physician.
On the contrary, if the response to the aforementioned conservative therapy is negative (ie the patient continues to experience pain behind the knee), the planning of more specific treatments becomes indispensable, some of which could also be somewhat invasive.
Conservative therapy: some more details
- Rest: it is a rest from all those activities that feed the painful sensation (eg: running, long walks, jumps etc.);
- Ice: if used in the right way, the ice has an incredible anti-inflammatory and pain-relieving power.
The indications for its use are: 4-5 packs per day on the painful area, for 15-20 minutes each (shorter or longer applications are ineffective);
- Anti-inflammatory drugs: consist of so-called NSAIDs or non-steroidal anti-inflammatory drugs; they are effective medicines with side effects;
- Elevation of the lower limb in pain: keeping the lower limb elevated reduces the blood supply to the knee; a lower blood supply to a suffering knee relieves pain and promotes the resolution of a possible swelling.
- Compression wrapping of the joint: serves to mitigate any swelling and possible sense of instability at the knee.
Special case: the treatment of pain behind the knee due to deep vein thrombosis
If the pain behind the knee depends on it is the result of a deep vein thrombosis, the therapy focuses exclusively on the use of thrombolytic drugs, that is drugs capable of causing the lysis of thrombi and pathological emboli.
Specific therapy: what does it consist of and how does it vary?
Among the more specific treatments that can follow an ineffective conservative therapy of pain behind the knee are:
- Localized injection of corticosteroids . Anti-inflammatory drugs are much more powerful than NSAIDs, but also more dangerous, if used improperly.
- Physiotherapy . Physiotherapy includes strengthening and stretching exercises for all the muscles of the suffering lower limb.
- Drainage of synovial and non-synovial fluid excesses.
It consists of introducing a special needle into the ailing knee (to be precise where it locates the swelling) and aspirating.
On some occasions, on aspiration, the treating physician accompanies the injection an anti-inflammatory drug belonging to the category of corticosteroids and / or the injection of a hyaluronic acid.
- Surgery . It is a possible solution for all those cases of pain behind the knee related to joint damage. In such circumstances, in fact, the surgery is used to "adjust" the joint.
The choice of specific therapy by the doctor has a decisive influence on the cause of pain behind the knee (in other words, specific therapy depends on the causal factor).
Prognosis
The prognosis in the presence of a pain behind the knee depends on the cause of the pain; in fact, if the cause is clinically insignificant, the pain behind the knee resolves quickly; vice versa, if the cause is clinically important, the pain behind the knee may disappear only after several weeks or several months of treatment.
Importance of early treatment
As a rule, when diagnosis and treatment are early, the disappearance times of a pain behind the knee are much narrower than when there is a delay in treatment.
