Aims

The Exeter V40 femoral stem is the most implanted stem in the National Joint Registry (NJR) for primary total hip arthroplasty (THA). In 2004, the 44/00/125 stem was released for use in ‘cement-in-cement’ revision cases. It has, however, been used ‘off-label’ as a primary stem when patient anatomy requires a smaller stem with a 44 mm offset. We aimed to investigate survival of this implant in comparison to others in the range when used in primary THAs recorded in the NJR.

Recent publications have drawn attention to the fact that some brands of joint replacement may contain variants which perform significantly worse (or better) than their ‘siblings’. As a result, the National Joint Registry has performed much more detailed analysis on the larger families of knee arthroplasties in order to identify exactly where these differences may be present and may hitherto have remained hidden. The analysis of the Nexgen knee arthroplasty brand identified that some posterior-stabilized combinations have particularly high revision rates for aseptic loosening of the tibia, and consequently a medical device recall has been issued for the Nexgen ‘option’ tibial component which was implicated. More elaborate signal detection is required in order to identify such variation in results in a routine fashion if patients are to be protected from such variation in outcomes between closely related implant types.

Cite this article: Bone Joint J 2023;105-B(3):221–226.

We report on the radiological findings in a series of 871 consecutive primary condylar knee replacements followed up for an average of four years. A new radiological sign has been identified, consisting of a smoothly tapering wedge of cement visible beneath the horizontal portion of the tibial component on the anteroposterior radiograph. This was found in 25.4% of our cases and appears to indicate a persistent soft-tissue imbalance following condylar arthroplasty of the knee. The cement-wedge sign was associated with a highly significant increase in radiolucent lines at the tibial cement-bone interface.

Serum 1.25 dihydroxyvitamin D concentrations were reduced in elderly patients with femoral neck fractures, irrespective of the presence of osteomalacia. This reduction was not attributable to a decrease in vitamin D binding protein. The low rate of bone turnover in these elderly patients might reduce the requirement for vitamin D and protect against the development of osteomalacia. Serum vitamin D metabolite concentration cannot be used as a screening test for osteomalacia in these patients.

In this study 201 elderly patients with femoral neck fractures were compared with 30 osteomalacic patients with the same injury. Hypocalcaemia and a raised alkaline phosphatase level are common biochemical abnormalities in elderly patients with femoral neck fractures. In only a minority of patients, however, were they associated with histologically proven osteomalacia. By using the combination of hypocalcaemia and a raised alkaline phosphatase it is possible to identify a subgroup (approximately 10% of all admissions) in whom osteomalacia is relatively likely.

In a series of over 1000 elderly patients with femoral neck fracture, who were routinely screened by iliac crest bone biopsy, a 2% prevalence of osteomalacia was found. This low figure suggests that osteomalacia is not a significant predisposing factor in the development of these fractures and that routine screening is not cost-effective.