1. Three patients are reported in whom a sudden acute internal derangement of the knee was caused by torsion of a pedunculated portion of the infrapatellar fat pad.

2. The symptoms and signs are described.

3. The pathological changes and the pathogenesis are discussed.

1 . A specific mechanism of injury can produce a tear of the articular disc of the wrist without any associated bony lesion.

2. Torn discs have been found associated with Colles's fractures and with dislocation of the inferior radio-ulnar joint.

3. The injury gives rise to clear-cut symptoms and definite physical signs.

4. Operation in fourteen cases has shown five types of tear of the disc.

5. Arthrographs of the wrist are helpful in establishing the diagnosis.

6. In isolated tears removal ofthe disc relieves the symptoms and does not prejudice function.

7. If there is other joint injury, removal of the disc cannot be expected to give as satisfactory a result.

Osteochondral fractures of the patella should be recognised early, loose bodies removed, and defects in the articular surfaces smoothed off, or the patella removed if it is extensively involved. Plication of the capsule on the medial side is recommended in order to prevent recurrence of the injury and to prevent dislocation of the quadriceps tendon. in cases where the patella is removed.