Pes Anserine Bursitis

Several bursa are seen around the knee area. These bursa include the suprapatellar, prepatellar, infrapatellar, and pes anserine. The pes answerine bursa is a small fluid filled sac located between the tibia and the three tendons of the Sartorius, Gracilis, and Semi-tendinosus.

These muscles are innervated by three separate nerves, the femoral, obturator, and the tibial branch of the sciatic nerve, respectively. Pes Anserine bursitis, or “breast stroke knee”, is an inflammatory condition of the medial knee at the pes anserine bursa that is common in swimmers.

What is the pes anserine?

The pes anserine is the common area of insertion for the three tendons along the proximal medial aspect of the tibia. This condition is also sometimes referred to as a “goosefoot” because the pes anserinus tendons resemble the shape of a goose foot. Pes Anserine bursitis is usually seen as causing pain, tenderness, and localized swelling after trauma or total knee replacement. The pain is seen below the joint line on the medial part of the proximal tibial with the bursa being deep to the tendons.

Treatment

Treatment consists of physical therapy, nonsteroidal anti-inflammatory medications, and injections. The physician will need to rule out meniscal tears, stress fractures, or osteonecrosis of the tibia, as these are all differential diagnosis.

Pronator Teres Syndrome

The nerve that is involved in pronator teres syndrome is the median nerve. Pronator Teres Syndrome is caused by a compression of the median nerve at the level of the elbow which occurs more in women. In the forearm, the median nerve runs between the two heads of the pronator teres muscle and then it lies between the flexor digitorum superficialis and flexor digitorum profundus muscles. This syndrome may be associated with medial epicondylitis. The principle symptoms of numbness in the radial 3 ½ fingers as well as thenar weakness which may be mistakenly attributed to carpal tunnel syndrome.

The most common cause of entrapment is due to compression of the median nerve between the two heads of the pronator teres muscle. This commonly occurs in people who perform repetitive forceful pronation of the forearm. Compression may be due to the thickening of the bicipital aponeurosis. The aponeurosis crosses from lateral to medial over the antecubital fossa and may irritate the median nerve. Compression of the nerve may also occur due to the fibrous arch of the origin of the flexor digitorum superficialis (FDS).

The median nerve runs down the medial side of the arm and passes 2 ½ to 4 cm below the level of the medial epicondyle before it enters between the two heads of the pronator teres. About 1% of

patients have a medial supracondylar humeral spur about 5cm proximally to the medial epicondyle. The ligament of Struthers is attached to this bony projection which connects the process to the medial epicondyle. The bony process points towards the elbow joint and the median nerve can become compressed by the supracondylar spur. The median nerve can also become trapped by the ligament of Struthers that extends from the supracondylar process to the medial epicondyle. The ligament of Struthers is different from the arcade of Struthers, which deals with the compression of the ulnar nerve around the elbow.

Paresthesia in these lateral 3 ½ fingers may occur with the compression of the median nerve at the elbow region or at the carpal tunnel region. These symptoms are similar to carpal tunnel syndrome but the symptoms are worse with rotation of the forearm. The patient will complain of dull aching pain over the proximal forearm with no nighttime symptoms. The pain is usually worsened by repetitive or forceful pronation. Tenderness of palpation to the pronator teres muscle will be detected. The median nerve gives off a palmar cutaneous branch before entering the carpal tunnel. Sensory disturbances over the palm of the hand occur due to involvement of the palmar cutaneous branch of the medial nerve and this occurs proximal to the carpal tunnel. Sensory disturbances in this area indicates median nerve problems proximal to the carpal tunnel. This differentiates between carpal tunnel syndrome and pronator teres syndrome.

There are specific provocative tests that produce the pain and distal paresthesia that are used to localize the site of compression. The Tinel’s sign at the wrist and the Phalen’s test will be negative. The Median nerve compression tests are negative at the carpal tunnel; however, there will be a positive Tinel’s sign at the proximal forearm. There will be abnormal sensation in the “palmar triangle”. When compression of the nerve involves the supracondylar process, the test is considered positive if symptoms of tingling worsen while tapping on the spur.

Occassionally, the spur can be felt. The pronator teres muscle can be assessed as the cause of the median nerve compression in different ways. Resisted forearm pronation with elbow flexion will test for compression at the two heads of the pronator teres muscle. During this test, the patient’s forearm is held in resisted pronation and flexion. While remaining in a pronated position, the forearm is gradually extended. Compression of the median nerve may also be tested by: resisted elbow flexion with forearm supination (compression at the bicipital aponeurosis) and resisted contraction of the FDS to the middle finger (compression at the FDS arch).

Differential Diagnosis

C6/C7 Radiculopathy occurs due to involvement of the nerves at these levels which will cause numbness of the thumb, index, and long fingers, as well as weakness of the muscles of the forearm that are innervated by the median nerve. The radial nerve part of C6-C7 will show normal function of the wrist extensors and the triceps.

X-rays, imaging and nerve conduction studies may be helpful in the diagnosis.

Treatment typically consists of rest, splints, and NSAIDs. Surgical decompression of the median nerve through all 4 or 5 possible sites of compression when non-operative management fails for 3-6 months. The results of surgery are variable. Full recovery is not always seen in all patients as only about 80% of patients improve from surgery. The skin incision may leave an unsatisfactory scar.

Froment's Sign

The Froment’s sign occurs due to weakness of the adductor pollicis muscle in ulnar nerve palsy. The adductor pollicis muscle has two heads:

1. Transverse Head
   1. Originiates from the anterior body of the third metacarpal
2. Oblique Head
   1. Originates from the base of the second and the third metacarpals as well as the trapezoid and capitate bones

The two heads of the adductor pollicis muscle then insert into the base of the proximal phalanx of the thumb and the ulnar sesamoid bones. The muscle is innervated by the deep branch of the ulnar nerve. The function of the adductor pollicis muscle is to adduct the thumb. It is important in pinch strength. When the ulnar nerve is injured, the adductor pollicis function is lost and thumb adduction will not occur.

The Foment’s Sign is used to test the function of the adductor pollicis muscle. When pinching a piece of paper between the thumb and index finger against resistance, the thumb IP joint will flex if the adductor pollicis muscle is weak. The flexion of the thumb occurs by the flexor pollicis longus, which is innervated by the median nerve. The flexor pollicis longus, which is innervated by the median nerve, substitutes the function of the adductor pollicis which is innervated by the ulnar nerve.