Angiogenin, a potent blood vessel inducing protein, was implanted into experimentally injured menisci of 75 New Zealand white rabbits. Localised neovascularisation occurred in 52% of the angiogenin-treated animals, and in 9% of the controls. Neovascularisation induced by angiogenin may enhance healing of injuries within the poorly vascularised meniscal fibrocartilage, and improve the results of meniscal repair.
The operation has the advantage of simplicity, and it avoids the slight danger of secondary cicatricial contracture of the nerve when it is transplanted anteriorly and implanted in muscle. There is a slight hazard from external injuries because the nerve is unprotected by the epicondyle.
1. Primary lumbar vertebral instability or "pseudo-spondylolisthesis" varies from about 3 millimetres to 1·7 centimetres, and is perhaps the commonest radiological sign associated with lumbo-sacral pain after the third decade of life. It was observed in 28·6 per cent of 500 consecutive cases of lumbo-sacral pain. The next commonest cause is gross disc degeneration, which is a late result of instability. 2. The secondary instability that may accompany a nuclear prolapse or osteoarthritis is excluded from this discussion. 3. This lumbar instability is an early sign of "incipient disc degeneration," occurring before narrowing of the disc space, sclerosis of the epiphysial rings, or osteophyte formation becomes evident. The instability in the lower lumbar region is caused by incomplete radial posterior tears, usually between the fourth and fifth lumbar vertebrae; and in the upper lumbar region from anterior concentric fissures or slits between some of the lamellae of the annulus fibrosus. 4. As shown radiologically, lumbar instability is commonest between L.4-5 and is rare between L.5 and sacrum because the facets between L.5-S.1 normally face forwards and backwards and thus resist anterior sliding. 5. The usual direction of antero-posterior sliding in the case of the upper four lumbar vertebrae is posteriorâthat is, the upper vertebra is displaced backwards on the one immediately below it during full extension in the erect position. The displacement tends to disappear on forced flexion, which may cause anterior displacement. On the other hand, the reverse displacement may exist between the fifth lumbar vertebra and the sacrum. 6. Operative treatment by bone grafting is a last resort in carefully selected individuals. After operation the patient rests in bed for three months without rigid splinting. Bone grafting is best for a localised lesion (affecting only one disc); it is generally not advisable if more than two discs are involved. 7. The results in thirty patients treated by spinal fusions showed that 70 per cent had no pain and resumed work, l3·3 per cent had improvement and resumed work, and l6·7 per cent were worse or no better.
One hundred and sixty-four cases of intramedullary nailing of the long bones have been studied with special reference to the difficulties and complications encountered. There was one death not attributable to the method. Two cases of pulmonal fat embolism and one case of thrombosis occurred, all in fractures of the femur. The lessons we have learned from our mistakes can be summarised as follows: 1 . The method requires technical experience and knowledge and is not suited to inexperienced surgeons or surgeons with little fracture material at their disposal. 2. Intramedullary nailing should only be used in fractures to which the method is suited. In general, comminuted fractures or fractures near a joint are unsuitable. 3. Open reduction is preferable to closed methods. 4. The nail should never be driven in with violence. It should be removed and replaced with a new one if difficulty is encountered when inserting it. 5. In fractures of the femur the nail should be driven in from the tip of the trochanter after careful determination of the direction. 6. The nail should be introduced only to the level of the fracture before exploring and reducing the fracture. 7. Distraction of the fragments must be avoided. 8. If the nail bends it should be replaced by a new one, at least in femoral fractures. 9. If union is delayed, the fracture should be explored and chip grafts of cancellous bone placed around it. 10. Improvised nails or nails which are not made of absolutely reliable material should never be used. 11 . Make sure that the nail is equipped with an extraction hole for removal.
