Popliteus strain

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Introduction

Popliteus muscle injuries are rarely isolated injuries and are mostly associated with other injuries of the posterolateral corner of the knee such as lateral collateral ligament injury, Anterior cruciate ligament injury , posterior cruciate ligament injury or meniscal tear.[1]

Clinically Relevant Anatomy

The Popliteus Muscle tendinous unit is unique in that the distal muscular attachment is designated the insertion and the tendinous proximal (femoral) attachment is designated the origin. The muscle inserts into a triangular area along the posteromedial aspect of the proximal tibial metaphysic above the soleal line. It forms the floor of the popliteus fossa. The tendon of the popliteus passes through the popliteal hiatus, entering the knee joint and inserting into the lateral femoral condyle at the end of the popliteal sulcus. The main tendinous component inserts into the lateral femoral condyle with variable aponeurotic attachments to the posterior horn of the lateral meniscus and the fibular head. The insertion into the lateral meniscus retracts and protects the meniscus in flexion, but this function has been disputed. The femoral insertion has a crescent shape, with the superior aspect being concave. The main tendon of the popliteus muscle consists of anterior and posterior fibers. The popliteus muscle is innervated by tibial nerves (L4-L5 and S1).

Functions of the Politeus Muscle at the Knee joint

The popliteus muscle functions as a dynamic internal rotator of the tibia. For this reason rupture of the popliteus muscle is usually associated with acute of the chronic posterolateral instability of the knee. The isolated rupture of the popliteus tendon musculotendinous unit is an uncommon injury. If isolated injury presents without significant instability.
In some cases the injury is extensive and may include disruption of the arcuate ligament complex, the lateral collateral ligament, both cruciates, and the menisci.

Mechanism of Injury

1. Contact Injuries / Traumatic Injuries

Blow to the anteromedial aspect of the tibia

2.Non-Contact Injuries/ Non-traumatic Injuries

External rotation Mechanism- A sudden external rotation of the partially flexed knee

Characteristics/Clinical Presentation

Lesions have been reported occurring by a non -contact external rotational mechanism: a sudden external rotation to a partially flexed knee ,A forced external rotation with a varus force application in some cases, or a forced external rotation with femur fixed have been described. Considering the type of tear, an overuse or degenerative mechanism could be considered as responsible for the partial tear

Clinically the affected patients present with an unnatural outward rotation of the tibia when bending the knee. Additionally ,other general symptoms often occur such as muscle swelling, edema or bleeding

• Pain over the lateral joint line
• pain at the back of the knee
• Pain on weight-bearing and stair-climbing
  
  

Types of Injuries

• Popliteus Tendon Avulsion
• Popliteus Tendon Tear (Partial/ Complete)
• Myotendinous Junction injury
• Muscle Contusion

Differential Diagnosis

1. Biceps femoris tendon strain
2. Lateral meniscus Injury
3. Lateral collateral ligament injury
4. Tibial nerve injury

Diagnostic Procedures

Complete tears of muscle can be clinically identified however the popliteus muscle is an exception. It is difficult to identify which structure of posterolateral complex is injured and therefore MRI is the preferred diagnostic tool.

An acute haemarthrosis and lateral pain in a stable knee should lead to suspicion of an isolated injury to the popliteus muscle-tendon unit. The diagnosis should be entertained in any acutely swollen knee with posterolateral tenderness and pain on resisted internal tibial rotation.
MRI of the knee should be performed to evaluate the nature of the injury. The diagnosis may be confirmed by arthroscopic examination of the knee.
In some cases, the ruptured popliteus tendon retracts distally through the popliteal hiatus and can no longer be seen in the joint.

Diagnostic Test

1. Garrick Test

Patient seated, hip and knee are both flexed to 90°. The patient actively externally rotates the lower leg and this is resisted by the examiner. A positive test is pain during the maneuver in the location of the popliteus muscle or tendon.

2. Shoe Removal Maneuver

This test is where pain is felt when trying to remove the shoe on the other side of the affected knee. This motion requires internal rotation of the affected leg to reach the heel of the other leg and can cause pain during the maneuver when there is injury to the popliteus muscle.

Knee outcome survey can be used as an outcome measure

Examination

Clinically the affected patients present with an unnatural outward rotation of the tibia when bending the knee. Additionally, other general symptoms often occur such as muscle swelling, edema or bleeding

Only a portion of the popliteus can be safely palpated due to the neurovascular structures that overlie it. The attachment on the tibial shaft can usually be reached as well as the tendon at the femoral condyle.

Rest described above in diagnostic tests.

POSTERIOR KNEE JOINT ASSESMENT
Patient should be assessed in supine and prone lying. Pain or ‘a feeling of fullness’ in the posterior knee can be the sign of a joint effusion.
Active and passive range of movement of the knee joint should be assessed in flexion, extension and tibio-femoral rotation.
Manual muscle testing of knee flexion should be performed with the knee joint positioned in both neutral and external rotation.
Palpation of the joint line, the tendons of the hamstrings, gastrocnemius and the popliteus should be carried out.
The posterior draw tests to check the integrity of the
It is essential to examine posterolateral rotational stability. There are several key tests to perform this such as the recurvatum test, reverse pivot shift and dial tests. The recurvatum test can be performed by holding the great toe of the involved limb with the knee fully extended. Gently lift the extremity and a PLC injury may be evident if the knee falls into hyperextension, varus and external rotation.

Medical Management

Medical management as line with other muscle injuries as it is mostly associate with other ligament and meniscus injuries guideline is RICE with anti-inflammatory drugs with analgesic medicines.In case of sever associate injury arthroscopic repair/reconstruction may require.

Physical Therapy Management

The treatment of isolated popliteus tendon ruptures has not been very well defined. Review (Method: MRI, Arthroscopy; Keywords: Popliteus tendon, rupture)of the literature shows 15 cases. Four were treated conservatively, in one case the avulsed chondral fragment was excised without repair of the popliteus tendon. In the remaining 10 cases, there was an osteochondral fracture as a result of avulsion of the tendon from the femoral attachment, and this fragment was reposited and fixed with screws.

Initial protocol is POLICE Principle (Protection,optimal loading,Rest,EIce,Compression.elevation)
Physiotherapy treatment is on a line with other soft tissues and muscle injuries, mobility exercises, ,,strengthening exercis, eccentricic training and many more rehab protocols depending upon patholo, associatede injuriesandd patients condition.

spray-and-stretch techniques, as described by Travell & Simons (1992),  if trigger point of pain present may be effective

Case Reports

A.R.Guha, K.A. Gorgees, D.I. Walker: Popliteus tendon rupture: a case report and review of the literature. Br. J. Sports Med 2003; 37:358-360

Isolated rupture of the popliteus tendon in a professional athlete. Burstein DB, Fischer DA Arthroscopy. 1990; 6(3):238-41. 

Isolated avulsion of the popliteus tendon. A case report. Mirkopulos N, Myer TJ Am J Sports Med. 1991 Jul-Aug; 19(4):417-9.