The MRC Working Party (United Kingdom) on CDH recently reported an ascertainment adjusted incidence of a first operative procedure for CDH of 0.78 per 1,000 live births, similar to the incidence before the commencement of the U.K. Screening programme. It also found that 70% of cases had not been detected before 3 months of age.

South Australia has had a similar clinical screening programme since 1964. This study determined the incidence of an operative procedure for CDH in the first 5 years of life among children born in South Australia between 1988 – 1993 (118,379 live births in total) and the proportion detected after 3 months of age.

Of 47 children identified as having non-teratologic DDH and operative procedures, 24 were diagnosed before one month of age. Some required operative intervention beyond 3 months of age despite early diagnosis. Only 22 (46.8%) had been diagnosed at or after 3 months of age 18 of the 47 had an open reduction and/or osteotomy while the remainder had arthrograms, closed reductions and/or tenotomy

The prevalence of non-teratologic DDH was 7.7 per 1,000 live births. The incidence of surgery in the first 5 years of life was 0.40 per 1,000 live births and only 0.19 per 1,000 for those late diagnosed at or after 3 months.

These results demonstrate that a screening programme can be successful, contrary to the findings of the UK MRC Working Party.

Osteoarthritis of the medial compartment of the knee often shows a specific pattern of anterior wear. Review of our revisions from a series of medial metal-backed Brigham unicondylar knee replacements performed between 1983 and 1989 showed that this wear pattern was common on the tibial polyethylene surface. We reviewed these cases retrospectively to compare the pattern of preoperative erosion with the wear of the prosthesis. In all 14 knees with severe anterior wear in a unicompartmental replacement, the prearthroplasty radiographs showed similar patterns, suggesting that the implanted tibial component may continue to be subjected to the same localised stresses that precipitated the failure of the original articular cartilage. Many tibial components implanted during the 1980s had an unacceptably thin anterior rim of polyethylene and it seems that greater thickness is essential at the anterior and peripheral margins of the tibial plateau.

Ten cases are described of catastrophic failure of the polyethylene liner of three different designs of uncemented acetabular component. Failure occurred as a result of either 'wearthrough' to the metal backing, liner fracture or a combination of both, at a mean of 4.6 years after implantation (2 to 7.6). At revision there was metallosis in all hips and osteolysis of the femur or the pelvis in six. Catastrophic failure was seen only in cups with a minimum polyethylene thickness of less than 5 mm.