Background: We have devised a modified Pivot Shift test with which to assess ACL deficiency which does not require forced tibio-femoral subluxation. The test is scored on patient reaction to the initiation of the pivot shift without actually having to elicit that ‘shift’ which can be painful. We call the test the Pivot Apprehension test.

Methods: We retrospectively analysed a cohort of 81 patients who were potentially ACL deficient and sought orthopaedic intervention over a period of 3 years and correlate their initial ‘pivot apprehension’ score with the degree of ACL deficiency found at subsequent arthros-copy and/or MRI.

Results: Using contingency tables and Fishers Exact test we calculate that the test has a positive predictive value (for predicting ACL Rupture) of 94% (p=0.026) and a sensitivity of 89% (Specificity 60%). Linear Regression analysis shows a correlation coefficient (r) of 0.47 (p=0.0008).

Conclusion: The data we have collected in this study show that the ‘Pivot Apprehension Score’ is a clinical tool with a high positive predictive value for ACL injury which provides the same information as the Pivot shift test without having to cause painful tibio-femoral sub-luxation thus obviating the clinical need to elicit ‘pivot shift’ in the conscious patient.

1. The use of a protein-free synthetic medium has provided a new technical approach to the study of fracture healing in vitro.

2. The tibiae of fourteen-day embryonic chicks were cut in half in the middle of the shaft, the fragments were placed in apposition and the explants grown in vitro for up to sixteen days. The process of bone repair was studied by means of histology and biochemical estimations.

3. The rate of growth in length of fractured bones was greater in an atmosphere containing 50 per cent of oxygen than in one with 20 per cent oxygen, thus emphasising the importance of an adequate oxygen supply for the regeneration of osteogenic cells.

4. The effect of varying the concentration of glucose in the medium was investigated. Two milligrams of glucose per millilitre was the most favourable for healing; higher levels caused fibroblastic changes in the cartilage cells and inhibited the proliferation of osteogenic cells at the fracture site.

5. Histological examination showed that many of the phenomena that occur in the repair of fractures in vivo can be reproduced in vitro in synthetic medium. Similar results were obtained whether the fracture was made in whole bones or in isolated shafts from which the cartilaginous ends had been removed; the latter are more favourable for biochemical study.