The Chiari osteotomy and various shelf procedures are used to augment the weight-bearing area in dysplastic acetabula. The new articular surface derives by metaplasia from the acetabular rim and joint capsule, and is therefore of poorer quality than congruous hyaline cartilage. We reviewed 32 patients after augmentation procedures, using conventional radiographs and three-dimensional reconstruction from CT scans. We showed that Chiari osteotomy and shelf procedures generally achieve less than complete cover, especially over the posterolateral quadrant of the femoral head. Our results suggest that alternative methods which reorientate the whole of the acetabulum are the treatment of choice. Augmentation procedures remain as a salvage option when reorientation is inappropriate or the original hyaline cartilage surface is absent, as in subluxed joints with a secondary acetabulum. Computerised assessment is recommended before operation to assess existing cover and the possible extent of provision of new cover.

The acetabular rim syndrome is a pathological entity which we illustrate by reference to 29 cases. The syndrome is a precursor of osteoarthritis of the hip secondary to acetabular dysplasia. The symptoms are pain and impaired function. All our cases were treated by operation which consisted in most instances of re-orientation of the acetabulum by peri-acetabular osteotomy and arthrotomy of the hip. In all cases, the limbus was found to be detached from the bony rim of the acetabulum. In several instances there was a separated bone fragment, or 'os acetabuli' as well. In acetabular dysplasia, the acetabular rim is subject to abnormal stress which may cause the limbus to rupture, and a fragment of bone to separate from the adjacent bone margin. Dysplastic acetabuli may be classified into two radiological types. In type I there is an incongruent shallow acetabulum. In type II the acetabulum is congruent but the coverage of the femoral head is deficient.

There is a specific type of displaced four-part fracture of the proximal humerus which consists of valgus impaction of the head fragment; this deserves special consideration because the rate of avascular necrosis is lower than that of other displaced four-part fractures. Using either closed reduction or limited open reduction and minimal internal fixation, 74% satisfactory results can be achieved in this injury.

In the Trillat procedure for recurrent anterior instability of the shoulder the coracoid process is osteotomised and tilted downward to act as a bone block, and a screw is used to fix it and the Bankart lesion to the anterior scapular neck. We reviewed 52 cases after a mean follow-up of 69 months. Results in 73% of shoulders were excellent, 10% were good, 7% fair and 10% poor. Dislocation recurred in 4%, but a positive apprehension sign was present in 10 other shoulders. Some degenerative changes were seen in 62% of shoulders, a complication known to be associated with bone-block procedures. The most important reason for loss of lateral rotation was iatrogenic impingement of the coracoid. This frequent and potentially serious complication can also cause posterior subluxation of the humeral head and osteoarthritis.

Symptomatic impingement of the rotator cuff between the humeral head and the coracoid process has been studied and three varieties recognised: idiopathic, iatrogenic and traumatic. In all three the clinical findings consisted of pain in front of the shoulder, referred to the upper arm and forearm, and especially felt during forward flexion and medial rotation; the pain could be reproduced by medial rotation with the arm in 90 degrees of abduction, or by adduction with the shoulder flexed to 90 degrees. Patients were relieved of their symptoms by restoring adequate subcoracoid clearance.

Anterior and posterior drawer tests of the shoulder are described. Their purpose is to detect anterior and posterior shoulder instability and thereby to eliminate some of the failures of operative treatment. Their value in assessing unidirectional and multidirectional instability both before and after operation is discussed.