Forty-four feet in 28 children previously treated by a one-stage posteromedial release operation (the Turco procedure) were reviewed clinically and radiologically to determine the cause of residual adduction of the forefoot. In 21 clinically adducted feet (48%) the main cause of residual deformity was metatarsus varus alone or metatarsus varus in spite of talonavicular overcorrection; in five feet the cause was talonavicular subluxation. There was no residual adduction in 23 feet (52%) but only 12 had normal radiographic measurements. In the remaining feet, various forms of spurious correction of metatarsus varus and talonavicular subluxation or both were seen, resulting in normal-looking feet. Recession of the origin of abductor hallucis and release of the short plantar muscles and fascia at the time of posteromedial release is recommended. The forefoot adduction was satisfactorily corrected in 91% of the feet subsequently operated on using this modified procedure.

The beneficial effect upon osteogenesis of imprenating bone grafts with autologous red marrow is well documented. The experimental findings reported in a previous paper suggested that prepared xenograft bone might provide a good medium for osteogenesis by marrow cells. This paper is a preliminary report of the first clinical attempt to use xenografts of bone combined with autologous red marrow. Kiel bone, which was found the most suitable, was impregnated with marrow aspirated from the iliac crest and, apart from one case of infection, gave excellent results in twenty-eight patients under conditions covering a wide range of indications for bone grafting. Further trials should allow a more valid assessment.

1. The humoral immune response of rats against sheep iliac bone grafts has been examined.

2. Fresh, marrow-containing grafts elicited a brisk and sustained antibody response. Attempts to wash out the marrow were not uniformly successful in removing cellular antigens from the grafts.

3. Decalcifying and freezing bone grafts at —20 degrees Celsius do not impair immunogenicity to any significant extent. Immunogenicity was found to be reduced in grafts subjected to freeze-drying.

4. Deproteinised Oswestry bone grafts and Kiel grafts gave rise to antibody production in a few recipients, and in the case of the former this response did not occur until after six or seven weeks from grafting.

5. The highest degree of osteogenesis in composite bone xenograft-autografts was found by Salama and colleagues (1973) to occur in Oswestry bone grafts. It is suggested that osteogenesis in xenografts may be impaired by an immune response.

1. This paper reports a histological study of the fate of sheep and calf cancellous bone grafts impregnated with autologous red marrow of Wistar rats and implanted intramuscularly as composite xenograft-autografts for two to twelve weeks. It also includes some biochemical estimations of certain types of sheep and calf bone used to prepare these composite grafts.

2. Only one of 223 devitalised bone xenografts implanted without autologous marrow formed new bone; in contrast 216 of 223 transplanted with marrow formed new bone.

3. The new bone formed by the composite grafts is derived from the autologous marrow. There was no evidence for an inductive effect upon the marrow of the various types of xenograft bone studied as described previously for allograft bone (Burwell 1966).

4. The highest score of new bone formation was found in composite grafts based on fully deproteinised sheep iliac bone prepared at Oswestry. Statistically this score was significantly higher than those registered by composite grafts prepared from intact (frozen and freeze-dried), decalcified (frozen and freeze-dried) and Kiel sheep bone, and by Kiel and Oswestry calf bone (Table II).

5. The histological evidence reported suggests that the high score with the sheep Oswestry composite grafts is because Oswestry bone is feebly immunogenic, if at all; and that such feeble or absent immunogenicity permits more marrow cells to differentiate into osteoblasts and lay down new bone without impediment.

6. The lower scores of new bone formation in most of the undeproteinised composite grafts of sheep origin–intact frozen, intact freeze-dried and Kiel–are attributed to residual immunogenicity within the organic material of the donor bone, because each type evoked the formation of mature plasma cells.

7. The Kiel bone grafts appeared to evoke less of a plasma cell reaction and may be less immunogenic than the intact and decalcified bone xenografts.

8. The sheep Oswestry CXA's formed significantly more new bone than did the calf Oswestry CXA's. This difference may be due to the different physical properties of the bone obtained from old sheep compared with the bone obtained from a young calf.