Injection Technique for Semimembranosus Insertion Syndrome

Indications and Clinical Considerations

Semimembranosus insertion syndrome is a constellation of symptoms including a localized tenderness over the posterior aspect of the medial knee joint, with severe pain elicited on palpation of the attachment of the semimembranosus muscle at the posterior medial condyle of the tibia ( Figs. 152.1 and 152.2 ). Semimembranosus insertion syndrome is most common after overuse or misuse of the knee, often after overaggressive exercise regimens. Direct trauma to the posterior knee by kicks or tackles during football also may result in the development of semimembranosus insertion syndrome. Coexistent inflammation of the semimembranosus bursa, which lies among the medial head of the gastrocnemius muscle, the medial femoral epicondyle, and the semimembranosus tendon, may exacerbate the pain of semimembranosus insertion syndrome.

On physical examination, the patient exhibits point tenderness over the attachment of the semimembranosus muscle at the posterior medial condyle of the tibia. The patient may have tenderness over the posterior knee and will exhibit a positive twist test for semimembranosus insertion syndrome ( Fig. 152.3 ). The twist test is performed by placing the knee in 20 degrees of flexion and passively rotating the flexed knee ( Fig. 152.4 ). The test result is positive if the pain is reproduced. Internal derangement of the knee also may be present and should be searched for on examination of the knee.

Plain radiographs are indicated for all patients with pain thought to be emanating from semimembranosus insertion syndrome to rule out occult bony disease, including tibial plateau fractures and tumor ( Fig. 152.5 ). On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, prostate-specific antigen, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging, computed tomography, and ultrasound imaging of the knee are indicated if internal derangement, fracture, occult mass, or tumor is suspected ( Figs. 152.6 and 152.7 ). Radionuclide bone scanning may be useful to rule out stress fractures not seen on plain radiographs. The injection technique described later serves as both a diagnostic and a therapeutic maneuver.

Clinically Relevant Anatomy

The semimembranosus muscle has its origin from the ischial tuberosity and inserts into a groove on the medial surface of the medial condyle of the tibia ( Fig. 152.8 ). The semimembranosus muscle flexes and medially rotates the leg at the knee and extends the thigh at the hip joint. A fibrous extension of the muscle called the oblique popliteal ligament extends upward and laterally to provide support to the posterior knee joint. This ligament, as well as the tendinous insertion of the muscle, is prone to development of inflammation from overuse, misuse, or trauma. The semimembranosus muscle is innervated by the tibial portion of the sciatic nerve. The common peroneal nerve is in proximity to the insertion of the semimembranosus muscle, with the tibial nerve lying more medially. The popliteal artery and vein also lie in the middle of the joint. Also serving as a source of pain in the posterior knee is the semimembranosus bursa, which lies among the medial head of the gastrocnemius muscle, the medial femoral epicondyle, and the semimembranosus tendon.