1. An analysis has been given of 100 consecutive knee arthrotomies performed on European miners working underground in the Witwatersrand Gold Mines.

2. The routine of clinical diagnosis, operation, and postoperative care has been described.

3. The operative findings have been analyzed. In four cases, no meniscal lesions were discovered at operation; in eighty-two cases, tears of the medial meniscus were found; in nine cases, tears of the lateral meniscus were seen. There were double tears in three cases, and discoid menisci in two. Of ninety-seven torn menisci, forty-nine were of the bucket-handle type.

4. The operative findings have been correlated with the signs found at examination.

a. Pain at the anteromedial joint line was found to be of considerable diagnostic significance. Absence of such pain contra-indicated arthrotomy for meniscal lesion.

b. It was shown that locking is frequently, but not always, due to a meniscal lesion. A stub of anterior cruciate ligament was the cause of locking in one case.

c. Meniscal damage may exist in the absence of wasting.

d. Fouché's "hot spot" on the medial facet of the patella is described.

e. The "crushing sign" is found to be not entirely pathognomonic of meniscal damage.

5. Erroneous diagnoses have been analyzed in some detail.

6. The end results of treatment are given, with disability assessments averaging 1.6 per cent. for the whole series.

7. Complications of the operation have been discussed.

8. The penalty of delay in operation has been found to vary greatly according to the type of lesion.

9. The findings in our investigation favor early and total meniscectomy, once an incontrovertible diagnosis has been made.