The details in technique which are most essential to ensure a perfect Syme's stump are the provision of a broad area of support for the heel flap by transecting the tibia and fibula as low as possible; the maintaining intact of the specialised weight-bearing qualities of the heel flap; and the proper placement of the heel flap under the cut ends of the tibia and fibula. If these aims are achieved a good and useful stump is assured; if they are neglected the stump will be imperfect and may be unsatisfactory and no further operation can restore the qualities of the heel flap which are lacking.

It must be recorded, however, that Syme's stumps which are not technically perfect often function so well that there has been no need to consider re-amputation. A loose heel pad can be held beneath the end of the bone by firm lacing of the corset of the prosthesis.If its area of bony support is reasonably large it may serve well, though not perfectly, as an end-bearing stump. Syme's stumps so completely unsatisfactory as to necessitate re-amputation have been those in which the plane of transection of the tibia is so high that the area supporting the heel flap is too small; or the weight-bearing qualities of the heel flap have been damaged; or there is instability of the heel flap which cannot be controlled; or there is impairment of nutrition of the heel flap.

One of the interesting aspects of spinal pathology having an important bearing on the treatment of backache is that the spine acts as an integrated whole and that damage sustained by one part frequently injures other structures in the spinal column. Thus disc degeneration may be associated with an extrusion of nuclear material; it may initiate degenerative changes in the posterior joints; it may predispose to tears of the posterior spinal ligaments; or it may give rise eventually to all of these lesions, any one of which may produce backache with or without sciatica. The sciatica may be referred pain or may be produced by nerve root pressure. Nerve root pressure in such instances is commonly due to an extrusion of nuclear material, but it may also be due to pressure on the nerve root within the foramen by a "squashed" disc or by a subluxated posterior joint.

Radiographs are of great value in the diagnosis of disc degeneration and they are of greater value in the assessment of the secondary effects that have taken place. With the use of bending films evidence of early degenerative changes may be obtained, tears of the supraspinous ligament can be detected, and abnormal movements of the posterior joints can be seen. Careful study of the antero-posterior and lateral projections will reveal evidence of subluxation of the posterior joints, chip fractures and degenerative arthritis in the zygapophysial articulations, and will clearly demonstrate overriding of the facets.

The investigation of subjective phenomena, such as backache, is fraught with many difficulties and it must be preceded by an investigation of the anatomy of the part and the anatomical variations, the normal and abnormal physiology and the pathological lesions that occur. Many of these changes of course may have no clinical significance, but it is only when armed with the knowledge of what may occur that we can tackle the problem of low back pain on a logical basis.

1. Peroneal spastic flat foot is a term loosely and often inaccurately used to describe rigid valgus feet developing from widely different causes.

2. The most common causes are two anomalies of the bones of the tarsus—the calcaneonavicular bar, and the talocalcaneal bridge. The first was described in 1921 by Sloman and in 1927 by Badgley; the other is described for the first time in this paper as an etiological factor in rigid flat foot though it has been recognised by anatomists for fifty years as a skeletal variation. The term peroneal spastic flat foot, as applied to these cases, is inaccurate since there is no spasm of the peroneal muscles. The deformity is a fixed structural deformity due to anomalous bone structure, and the apparent spasm of peroneal muscles is in reality an adaptive shortening. A better term would be rigid flat foot due to talocalcaneal bridge or calcaneonavicular bar.

3. The smaller group of patients who suffer from inflammatory lesions of the tarsal joints, chiefly due to rheumatoid arthritis, do in fact develop valgus deformity from peroneal spasm. The resemblance between the two groups is superficial and it is limited to the apparent similarity of the deformity. Though it might be justifiable to designate this type as peroneal spastic flat foot, it would be better to use the more accurate title—arthritic flat foot with peroneal spasm.

4. Lipping of the upper margin of the talonavicular joint strongly suggests the existence of one or other of the congenital anomalies. Both anomalies are visualised only by special radiological projections.