David Bryde, Linda Khong, Palina Karakasidou, Nessa Waters, Michael Wong
Clinical Implications
The popliteus muscle contributes to the movement of knee flexion (Williams et al 1995). It also initiates and maintains internal tibial rotation during gait, thus maintaining knee rotary stability (Basmajian and Lovejoy 1971, Fulkerson and Gosling 1980, Mann and Hagy 1977). Harner et al (1998) report that it acts synergistically with the posterior cruciate ligament (PCL) to help prevent forward translation of the femur on the tibia.
There are various popliteal pathologies, such as tendon subluxation (Crites et al 1998 and McAllister and Parker 1999), popliteus tenosynovitis / tendinitis (Howard et al 1992 and Mayfield 1977) and myofascial pain syndrome (Travell and Simons 1999).
There are two main palpation tests for diagnosing popliteus pathology. Bruckner and Khan (1999) and Travell and Simons (1999) have described palpation of the muscle belly posterolaterally at the knee joint in 30° of knee flexion. Griffin (1984) and Mayfield (1977) describe palpation of the tendon immediately anterior to the LCL in 90° of knee flexion with the hip abducted, laterally rotated and flexed. In the present dissection, it was not possible to support the validity of the latter test, as the tendon was deep to the LCL.
The authors consider that the popliteus muscle could contribute to rehabilitation of a PCL lesion. The PCL is placed under tension with posterior translation of the tibia and deep knee flexion (Garrett et al 2000). As the popliteus muscle internally rotates the tibia and helps to reduce its posterior translation, the authors propose that strengthening of the popliteus muscle will help to decrease tension on the PCL during loading. This would be especially important following a PCL reconstruction. The proposed procedure for strengthening of this muscle would be knee flexion, with resisted tibial internal rotation. This could be achieved in a sitting position with the knee flexed to approximately 90 degrees, with resisted tibial internal rotation by means of ‘theraband’ being placed around the foot. It is important that the medial hamstrings are not activated during this movement, as they will produce a posterior translation of the tibia, thereby tensioning the PCL. This is achieved by using the fingers to palpate the medial hamstrings as a means of biofeedback for hamstring inhibition.
It is well documented that popliteal muscle/tendon injuries occur most frequently with downhill running or walking (Garrett et al 2000, Mayfield 1977, Travell and Simons 1999). This may be due to the repetitive use of the popliteus musculotendinous unit in preventing anterior translation of the femur on the tibia, as popliteus muscle activity is proportional to increased load on a flexed knee (Davis et al 1995). The authors propose that strengthening of the popliteus muscle, as previously discussed, will strengthen the musculotendinous unit and thereby minimise trauma during downhill running activities. Many athletes use hill running as a functional lower limb strengthening exercise, and we believe that strengthening of the popliteus muscle may prove valuable in preventing injuries in this population.
Strengthening of the popliteus muscle could also be beneficial for people who have genu recurvatum. This condition can sometimes be painful in adults and children. The authors propose that decreasing the posterior translation forces of the tibia by increasing the strength and tone of this muscle could reduce pain levels in this population.
