Pes anserine bursitis (PAB) is a common source of pain on the inside of the knee. The condition involves inflammation of the pes anserine bursa, a small, fluid-filled sac situated beneath a group of tendons on the inner part of the lower leg. Effective treatment involves a multi-step approach, beginning with immediate pain management and progressing toward long-term muscle strengthening and flexibility.
Anatomy and Causes of Inflammation
The pes anserine bursa is located approximately two inches below the knee joint line on the inner side of the tibia (shinbone). This bursa cushions the space between the tibia and the three conjoined tendons of the sartorius, gracilis, and semitendinosus muscles. These muscles are responsible for flexing the knee and internally rotating the leg.
Inflammation occurs when the bursa becomes irritated due to repetitive friction and stress from these tendons gliding over the bone. Common contributing factors include overuse, such as in runners, and underlying biomechanical issues. These issues include excessive pronation of the feet, a knock-kneed alignment, or tight hamstring and quadriceps muscles. Obesity and knee osteoarthritis also increase the likelihood of developing PAB.
Initial Steps for Pain Management
Managing the initial acute pain and swelling associated with PAB focuses on reducing inflammation and resting the affected area. The standard initial approach includes the R.I.C.E. protocol for immediate relief. Rest involves temporarily avoiding activities that cause pain, especially repetitive knee bending or impact like running or climbing stairs.
Ice should be applied to the tender area on the inner knee for 15 to 20 minutes, ideally every three to four hours during the first 48 to 72 hours of acute pain. Cold application helps to constrict blood vessels, which reduces local swelling and decreases pain perception.
Compression, typically using an elastic bandage, minimizes swelling and provides gentle support, but the wrap should not be applied so tightly that it causes numbness. Elevation of the leg, keeping the knee at or slightly above heart level, further assists in reducing fluid accumulation.
Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, help manage both pain and swelling. Follow the recommended dosage and do not use these medications for more than 7 to 10 days without consulting a healthcare provider due to potential side effects. If walking is severely painful, temporary assistive devices like crutches or a cane can take pressure off the knee.
Targeted Stretching and Strengthening
Once the acute pain subsides, the next phase focuses on long-term rehabilitation to address muscle imbalances and tightness contributing to PAB. Consistent stretching is necessary, as tight hamstrings and adductors can exert excessive pulling force on the bursa, increasing friction.
Stretching
Stretching should target the hamstrings and quadriceps. For the hamstrings, a simple stretch involves sitting on the floor with one leg straight and reaching toward the toes, holding for 30 seconds. For the quadriceps, a prone knee bend stretch involves gently pulling the heel toward the buttocks until a stretch is felt in the front of the thigh. These stretches should be performed slowly and held without bouncing, focusing on a gentle pull rather than sharp pain.
Strengthening
Strengthening exercises are important to stabilize the knee joint and correct biomechanical issues. Targeting the hip abductors is particularly beneficial, as weakness in these muscles can lead to improper knee alignment during movement. Exercises like side-lying leg lifts or clamshells engage the gluteal muscles to improve stability. Quadriceps strengthening, especially focusing on the final degrees of knee extension, also supports the knee joint. Gentle exercises include straight leg raises or quad sets, where the thigh muscle is tightened against the floor. A regular routine should incorporate two sets of 15 repetitions for strengthening exercises and holding stretches for 15 to 30 seconds, three times each.
Medical and Advanced Treatment Options
When conservative home treatments and an exercise program do not provide sufficient relief after several weeks, medical intervention may be necessary. A common second-line treatment is a corticosteroid injection, which delivers a potent anti-inflammatory medication directly into the bursa. This procedure can offer substantial pain relief and reduce swelling, though it is generally reserved for cases refractory to initial management.
Corticosteroid injections carry a small risk of side effects, including temporary pain flare-up, skin discoloration, or, rarely, damage to adjacent tendons if the medication is inadvertently injected into them. Physical therapy referral is also a standard recommendation. A therapist can assess gait, address specific muscle weaknesses, and use modalities like ultrasound or electrical stimulation to aid recovery.
In extremely rare and persistent cases where inflammation is severe, a physician may consider aspiration, which involves draining the excess fluid from the bursa. Surgical removal of the bursa (bursectomy) is the final option, reserved only for chronic, debilitating cases that have failed to respond to all other treatments. Consult a physician immediately if pain is severe or worsening, or if signs of infection appear, such as fever, redness, or warmth radiating from the knee. If pain does not begin to improve after 7 to 10 days of consistent home care, a medical evaluation is warranted to rule out other conditions.