1. This is a preliminary report of an attempt to determine an objective reference point or "point of motion" during flexion and extension of the lumbar spine.

2. The method described uses superimposition of lateral radiographs taken in flexion and extension with the patient standing.

3. In seventy-eight radiographically normal subjects with no symptoms a "point of motion" was determined for each of the lowest three disc levels. At each level these points clustered within a specific zone approximately 2·5 centimetres square. Sixty-four per cent fell within a square centimetre.

4. In a comparative study of twenty-four patients with confirmed pathology, the "point of motion" fell outside the larger zone at the level of pathological change in 65 per cent of the disc levels.

5. The determination of the "point of motion" is a special technique for studying spinal motion. Its role as a diagnostic and prognostic aid in assessing patients with back pain is the subject of continuing study.

1. The syndrome of spinal stenosis is due to compression of the cauda equina from structural narrowing of the lumbar spinal canal.

2. Patients with this syndrome present symptoms of cauda equina claudication or of unremitting bizarre back pain and sciatica.

3. The compression of the cauda equina is always posterior and postero-lateral and is caused by narrowing of the lateral recesses and of the dorso-ventral diameter of the spinal canal.

4. The diagnosis can be made only by myelography. The only form of successful relief of the nerve root compression in spinal stenosis is adequate lateral and longitudinal decompression.

1. The history of open operations on fractures of the calcaneum is reviewed.

2. A report is given of the results of treatment of comminuted and depressed fractures of the calcaneum by primary arthrodesis by a modified Gallie procedure.

3. Of twenty-nine patients, twenty-seven returned to full employment within an average of 6·4 months. Twenty-five of these returned to their previous jobs.

4. Poor tendo calcaneus function and lateral sub-malleolar pain were found to be closely allied; both complaints were absent in the usually successful case and occurred only where there had been some complication.

5. It is contended that subtalar arthrodesis is a successful method of treatment for this fracture, but that the operation should be performed soon after the injury in order that the deformity may be corrected.