CHAPTER XIX
THE BURSAE
Anatomy--Normal and adventitious bursae--Injuries: Bursal
haematoma--DISEASES: Infective bursitis; Traumatic or trade
bursitis; Bursal hydrops; Solid bursal tumour; Gonorrhoeal and
suppurative forms of bursitis; Tuberculous and syphilitic
disease--Tumours--_Diseases of individual bursae in the upper and
lower extremities_.
A bursa is a closed sac lined by endothelium and containing synovia. Some are normally present--for instance, that between the skin and the patella, and that between the aponeurosis of the gluteus maximus and the great trochanter. _Adventitious bursae_ are developed as a result of abnormal pressure--for example, over the tarsal bones in cases of club-foot.
Injuries of Bursae.#--As a result of contusion, especially in bleeders, haemorrhage may occur into the cavity of a bursa and give rise to a _bursal haematoma_. Such a haematoma may mask a fracture of the bone beneath--for example, fracture of the olecranon.
Diseases of Bursae.#--The lining membrane of bursae resembles that of
joints and tendon sheaths, and is liable to the same forms of disease.
Infective bursitis# frequently follows abrasions, scratches, and wounds
of the skin over the prepatellar or olecranon bursa, and in neglected
cases the infection transgresses the wall of the bursa and gives rise to
a spreading cellulitis.
Traumatic or Trade Bursitis.#--This term may be conveniently applied to
those affections of bursae which result from repeated slight traumatism
incident to particular occupations. The most familiar examples of these
are the enlargement of the prepatellar bursa met with in housemaids--the
"housemaid's knee" (Fig. 113); the enlargement of the olecranon
bursa--"miner's elbow"; and of the ischial bursa--"weaver's" or
"tailor's bottom" (Fig. 116). These affections are characterised by an
effusion of fluid into the sac of the bursa with thickening of its
lining membrane. While friction and pressure are the most evident
factors in their production, it is probable that there is also some
toxic agent concerned, otherwise these affections would be much more
common than they are. Of the countless housemaids in whom the
prepatellar bursa is subjected to friction and pressure, only a small
proportion become the subjects of housemaid's knee.
_Clinical Features._--As these are best illustrated in the different
varieties of prepatellar bursitis, it is convenient to take this as the
type. In a number of cases the inflammation is acute and the patient is
unable to use the limb; the part is hot, swollen, and tender, and
fluctuation can be detected in the bursa. In the majority the condition
is chronic, and the chief feature is the gradual accumulation of fluid
constituting the _bursal hydrops_ or _hygroma_. When the affection has
lasted some time, or has frequently relapsed, the wall of the bursa
becomes thickened by fibrous tissue, which may be deposited irregularly, so that septa, bands, or fringes are formed, not unlike those met with in arthritis deformans. These fringes may be detached and form loose bodies like those met with in joints; less frequently there are fibrinous bodies of the melon-seed type, sometimes moulded into circular discs like wafers. The presence of irregular thickenings of the wall, or of loose bodies, may be recognised on palpation, especially in superficial bursae, if the sac is not tensely filled with fluid. The thickening of the wall may take place in a uniform and concentric fashion, resulting in the formation of a fibrous tumour--_the solid bursal tumour_--a small cavity remaining in the centre which serves to distinguish it from a new growth or neoplasm.
[Illustration: FIG. 113.--Hydrops of Prepatellar Bursa in a housemaid.]
The _treatment_ varies according to the variety and stage of the
affection. In recent cases the symptoms subside under rest and the
application of fomentations. Hydrops may be got rid of by blistering, by tapping, or by incision and drainage. When the wall is thickened, the most satisfactory treatment is to excise the bursa; the overlying skin being reflected in the shape of a horse-shoe flap or being removed along with the bursa.