Pain at the back of the knee can be secondary to several pathologies. One less common cause of posterior knee pain is low hamstring tendonitis at the knee, also called distal hamstring tendinopathy. So, what is this condition, and how do we manage it?
What are the distal hamstring tendons?
The hamstring muscles comprise the biceps femoris, semitendinosus, and semimembranosus muscles. These muscles form strong tendons attaching to the tibia and fibula at the lower part of the leg.
Overuse of the hamstring tendons from excessive sport leads to a pathology called tendonitis. Tendon swelling and inflammation can form on the knee’s inside (semimembranosus) or outside (biceps femoris). Most people who develop low hamstring tendonitis are ususally runners or active in sports that involve a change of direction and acceleration. Also, cyclists are prone to overloading the hamstring tendons, particularly with a change in cadence or intensity.
Symptoms of low hamstring tendonitis
Generally, most cases present as pain in the back of the knee. Ususally, lower hamstring pain worsens at the beginning of activity and warms up as the movement continues. Often, the exact location of lower hamstring pain is challenging to localise. It may be deep and to the inside of the back of the knee (semimembranosus tendon) or outside of the knee close to the head of the fibula (biceps femoris tendon).
Often, pain is accompanied by a generalised weakness of hamstring strength.
Generally, we make a diagnosis based on a thorough clinical assessment. For example, examining someone with distal hamstring tendinopathy demonstrates tenderness at the posterior knee. Contracting the hamstring muscle brings pain in the back of the knee.
In many cases, we use imaging to confirm a diagnosis and exclude other causes of pain at the back of the knee. In general, we need to exclude other local causes of pain, including intra-articular cartilage damage, calf muscle tears, and Baker’s cyst. Also, pathology in the lumbar spine can refer to the back of the knee.
Treatment of low hamstring tendonitis
Overall, treatment of distal hamstring tendinopathy is notoriously slow, like other cases of tendonitis.
Simple treatments
We often start with simple treatments such as activity modification, rest from high-intensity sport, anti-inflammatory tablets such as ibuprofen, and a comprehensive strengthening program to build strength in the hamstring and surrounding upper and lower muscles. See a rehab specialist who can guide you through a step-by-step program, including a return to sports program.
Rehab mirrors exercise therapy for proximal hamstring tendonitis. This blog outlines rehab in more detail.
Shockwave therapy for low hamstring tendonitis
We often use shockwave therapy to assist in managing more complex cases that don’t settle with simple treatments. Focussed or radial shockwave is helpful to desensitise the tendon and allows for strength progression.
Generally, for hamstring origin tendonitis, we recommend higher-strength focussed shockwave.
Ultrasound-guided cortisone injections
In more complex cases, we consider injection therapy.
Traditionally, we use low-dose cortisone injected around the tendon to reduce pain and allow further rehab. In addition, doctors perform cortisone injections directed by ultrasound to improve accuracy and minimise side effects. However, cortisone can damage the tendon, so we need to use a lower dose of cortisone than used for joints.
Alternatives to cortisone include platelet-rich plasma (PRP). First, we obtain PRP by taking whole blood from a person’s arm. Next, this blood is centrifuged to separate the plasma from the heavier red cells. Finally, we inject this plasma into the region of tendonitis to induce healing. Although we have good evidence for using PRP in some tendons, such as tennis elbow, we have little evidence for use in hamstring tendonitis. Also, PRP can worsen your tendon pain in the short term (2-4 weeks) before improving pain in the medium term (3-6 months).
Final word from Sportdoctorlondon about low hamstring tendonitis at the knee
Low hamstring tendonitis is common in active sportspeople and presents with pain at the back of the knee. You must see a sports doctor with experience in assessing and managing this condition.
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