CASE REPORTS

The precise etiolog ’ of the simple ganglion has always been a matter of some dispute. In most of the cases to be described a definite connection with the neighbouring joint or joint capsule was established at operation. On only one occasion did tile histology of the excised ganglion resemble that of synovial membrane. However, it is generally accepted that if a synovial herniation becomes loculated as in a Baker’s cyst, the lining membrane can undergo a metaplastic change to mesothelium. \Vhile the predisposing factors responsible for the formation of ganglia are by no means certain, accumulated evidence suggests that trauma to the joint ma\ ’ be important, and in cases of established osteoarthritis they are common. Simple ganglia seldom give rise to serious symptoms and indeed their unsightly appearance in the neighbourhood of the wrist and hand is often the sole reason for seeking advice: in these circumstances the diagnosis and treatment are simple. The following collection of cases illustrates a less frequent manner in which they may present, namely by causing pressure on an adjacent nerve and producing a variety of neurological symptoms. Since the ganglia were found to arise near joints, cases will be described in relation to tile elbow and wrist in the upper limb and the knee and ankle in the lower limb. A series of cases of compression of the deep branch of the ulnar nerve in the hand by carpal ganglia is described elsewhere by Mr H. J. Seddon.* FIG. 1 Case l-Radiographs of the elbow showing osteoarthritic changes