Among the hundreds of muscles found in the human body, the popliteus is the most unique in structure. The popliteus has a close association to an articular meniscus and an inversion of both its, fleshy and tendinous, attachments. In other words, the tendon is the origin, and the fleshy attachment forms its insertion. Inflammation of the tendinous portion of the popliteus muscle, also known as popliteus tendinitis, is a clinically significant condition that can produce substantial adverse effects.
Recognizing and correctly diagnosing this painful inflammatory condition is urgently essential because it can severely limit physical function, and eventually lead to unnecessary and preventable surgical procedures. Furthermore, most patients respond reasonably well to physical therapy and Non-Steroidal Anti-inflammatory Drugs; thus immediate treatment results in a lower incidence of recalcitrance.
WHAT DOES IT MEAN TO HAVE POPLITEUS TENDINITIS
When we speak of having popliteal tendinitis we refer to tearing or inflammation of the popliteus muscle´s tendinous attachment, which crosses from inside the tibia to the outside of the femur. The popliteus muscle performs a variety of different and vital functions in the leg.
ANATOMY OF THE POPLITEUS MUSCLE
Proximally, the popliteus muscle inserts into the lateral femoral condyle anterior and inferior to the fibular collateral ligament. Its secondary attachments lie proximally to the fibular head and lateral meniscus. Distally, the popliteus muscle arises from the proximal border of the tibia as a broad flat muscle.
The popliteus muscle is the primary internal rotator of the tibia. In other words, during the initial flexion from an extended position, the popliteus muscle unlocks the knee. Additionally, the popliteus muscle provides stability, controls lateral meniscus displacement, and resists external rotation and posterior tibial movement.
CAUSES OF POPLITEUS TENDINITIS
It has been suggested by various studies that overexertion of the quadriceps muscle leads to inflammation of the popliteus tendinous attachment. It is believed that when the fatigued quadriceps cannot adequately resist forward displacement of the femur on the tibia, an inordinate amount of undue stress occurs on the secondary restraints, which has the undesired effect of overwhelming the popliteus muscle.
Typically, popliteus tendinitis has been associated with downhill running and other motions that cause sudden deceleration. It is believed that as the popliteus muscle activates to prevent excessive posterior tibial translations relative to the femur, it becomes overburdened.
SYMPTOMS OF POPLITEUS TENDINITIS
Typically, pain onset is gradual and mainly located along the proximal aspect of the popliteus tendon. This can occur at the femoral origin or along the posterolateral portion of the knee. Pain is primarily present during weight bearing and when the knee is flexed between 15 and 30 degrees.
It is extremely important to diagnose popliteus tendinitis as it can easily be misdiagnosed correctly. Often, a tear of the lateral meniscus or the presence damage to the lateral articular compartment causes similar symptomatology. Additionally, a popliteal cyst can present similar patterns of pain.
Other conditions that can be confused for popliteus tendinitis are inflammation to the lateral head of the gastrocnemius, biceps femoris tendon, or iliotibial band. However, in the presence of popliteus tendinitis, no catching, locking, or giving away of the knee would be observed. Furthermore, popliteus tendinitis induces no observable effusion of the joint.
TREATMENT OF POPLITEUS TENDINITIS
It is best to rest the affected knee as much as possible to allow you to prevent future injuries. Ice helps to relieve pain caused by the swelling tissue. Moreover, it generates vasoconstriction, limiting the flow of blood and lymph fluid to the area. The primary directive should be to avoid putting loads on the field where we feel pain; you must apply ice on the muscle to reduce the painful inflammation between 4 to 6 times day for 20 minutes.
As noted before, the popliteus tendon is a dynamic stabilizer subject to fatigue. Thus, as the popliteus aids in the prevention of posterior tibial translation, an excessive exertion of the quadriceps muscle causes undue strain on the popliteus tendon. Therefore, a rehabilitation program that emphasizes the eccentric strengthening of the quadriceps is recommended. Improving flexibility is also highly encouraged.
If patients do not respond favorably to physical therapy, Non-Steroidal Anti-Inflammatory Drugs and localized corticosteroid therapies are administered.
POPLITEUS MUSCLE EXERCISES
A large number of physiotherapists agree that runners may suffer a higher percentage of injuries popliteus tendon than other athletes. Having excessive pronation increases the chances of suffering from popliteal injuries. In these cases, it is not possible to generalize, but it would be advisable to consult with a physiotherapist how to proceed with training.
Here are several exercises that can help to regain function in the popliteal muscle and diminish the severity of the inflammation.
- Leg Curls: Lie on your stomach with your feet out towards a resistance band that has been attached to a solid surface. Lift the heel of the affected leg up and in towards your Gluteus Maximus. Resistance can be adjusted based on relative levels of comfort and pain tolerance. Gradually return to the starting position and repeat between 20 and 25 repetitions.
- Step Task: This workout will help rehabilitate the popliteal muscle and help to promote stabilization of the knee joint. Using an aerobics step, place one foot on the top and while keeping the knee slightly bent, step forward with your other leg. Subsequently, step down and backward, then to the right and left of your planted foot. When performed in multiple directions as described, this exercise will rebuild functional strength in the popliteal muscle and its tendinous attachment. Repeat between 20 and 25 repetitions.
- Last, R. J. “The popliteus muscle and the lateral meniscus.” The Journal of Bone and Joint Surgery. British volume 32.1 (1950): 93-99.
- Basmajian, J. V., and J. F. Lovejoy Jr. “Functions of the popliteus muscle in man: a multifactorial electromyographic study.” JBJS 53.3 (1971): 557-562.
- Stanish, William D., R. Mitchell Rubinovich, and Sandra Curwin. “Eccentric exercise in chronic tendinitis.” Clinical orthopaedics and related research 208 (1986): 65-68.
- Almekinders, Louis C., and John D. Temple. “Etiology, diagnosis, and treatment of tendonitis: an analysis of the literature.” Medicine and science in sports and exercise 30.8 (1998): 1183-1190.