Hamstring Tendinitis – The Clinical Syndrome
Hamstring tendinitis is occurring with greater frequency as a result of the increased interest in jogging and the use of exercise equipment for lower extremity strengthening. The onset of hamstring tendinitis is usually acute, occurring after overuse or misuse of the muscle group. Inciting factors may include long-distance running, dancing injuries, or the vigorous use of exercise equipment for lower extremity strengthening. The pain is constant and severe, with sleep disturbance often reported. The patient may attempt to splint the inflamed tendon by holding the knee in a slightly flexed position and assuming a lurch-type antalgic gait. In addition to the pain, patients with hamstring tendinitis often experience a gradual decrease in functional ability with decreasing knee range of motion, making simple everyday tasks, such as walking, climbing stairs, or getting into an automobile, quite difficult. With continued disuse, muscle wasting may occur and a stiff knee may develop.
What are the Symptoms of Hamstring Tendinitis
Patients with hamstring tendinitis experience severe pain on palpation over the tendinous insertion, with the medial portion of the tendon more commonly affected than the lateral portion. Crepitus or a creaking sensation may be felt when palpating the tendon while the patient flexes the affected knee. No mass in the popliteal fossa is present as is seen with Baker cyst. The neurological examination of a patient with hamstring tendinitis is normal.
How is Hamstring Tendinitis diagnosed?
Plain radiographs are indicated in all patients with posterior knee pain. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated. Magnetic resonance imaging (MRI) and ultrasound imaging of the knee is indicated if internal derangement, occult mass, Baker cyst, or strain or partial tendon disruption is suspected. Injection of the hamstring tendons serves as a diagnostic and therapeutic maneuver.
The most common cause of posterior joint pain is a Baker cyst. It is a herniation of the synovial sac of the knee. It may rupture spontaneously and may be misdiagnosed as thrombophlebitis. Occasionally, injury to the medial meniscus may be confused with hamstring tendinitis. Primary or metastatic tumors in the region, although rare, must be considered in the differential diagnosis.
Initial treatment of the pain and functional disability associated with hamstring tendinitis should include a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold may be beneficial. Patients with hamstring tendinitis should avoid the repetitive activities responsible for the development of this painful condition. For patients who do not respond to these treatment modalities, injection of the hamstring tendons with a local anesthetic and steroid may be a reasonable next step. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle related complications.
Complications and Pitfalls
Failure to diagnose primary knee pathological processes (e.g., tears of the medial meniscus) may lead to further pain and disability. MRI should help identify internal derangement of the knee. The possibility of trauma to the hamstring tendon from the injection itself is ever present. Tendons that are highly inflamed or previously damaged are subject to rupture if they are directly injected. This complication can be greatly decreased if the clinician uses gentle technique and stops injecting immediately if significant resistance to injection is encountered. The proximity to the common peroneal and tibial nerve and the popliteal artery and vein makes it imperative that this procedure be done only by clinicians well versed in the regional anatomy and experienced in performing injection techniques. Many patients report a transient increase in pain after the injection technique. Although rare, infection may occur if careful attention to sterile technique is not followed.
The musculotendinous insertion of the hamstring group of muscles is susceptible to the development of tendinitis for two reasons. First, the knee joint is subjected to significant repetitive motion under weight-bearing conditions. Second, the blood supply to the musculotendinous unit is poor, making healing of microtrauma difficult. Calcium deposition around the tendon may occur if the inflammation continues, complicating subsequent treatment. Tendinitis of the musculotendinous insertion of the hamstring frequently coexists with bursitis of the associated bursa of the knee joint, creating additional pain and functional disability. This injection technique is extremely effective in the treatment of pain secondary to hamstring tendinitis. Coexistent bursitis and arthritis may contribute to knee pain and may require additional treatment with a more localized injection of a local anesthetic and depot steroid. This technique is a safe procedure if careful attention is paid to the clinically relevant anatomy in the areas to be injected. The use of physical modalities, including local heat and gentle range-of-motion exercises, should be introduced several days after the patient undergoes this injection technique. Vigorous exercises should be avoided because they would exacerbate the symptoms.