Infection of the ulnar bursa is the most serious hand infection, because it contains all the flexor tendons of a patient's fingers. His whole hand is oedematous, his palm is moderately swollen, and there may a fullness immediately above his flexor retinaculum. His flexed fingers resist extension, particularly his little one, and least of all his index.
The radial and ulnar bursa sometimes communicate with one another. So if one of them has been infected, infection may follow in the other a day or two later.
INFECTION OF THE ULNAR BURSA. For the general method for a hand infection, see Section 8.1.
Open the tendon sheath of the patient's little finger with palmar flaps, using incisions 9a and if necessary 9b.
Incise his skin and deep fascia over the antero-medial side of his fifth metacarpal, using incision 3. Separate his abductor and flexor digiti minimi muscles from the bone. Retract them forwards and you will see his opponens digiti minimi muscle. Divide this close to its attachment to his flexor retinaculum. Divide his flexor retinaculum deep to opponens digiti minimi[md]you will see his bulging ulnar bursa. Wash this out, as for a tendon sheath infection (8.12)
You can also drain his middle palmar space through this incision, as in Section 8.9.