We have reviewed six patients with old tuberculosis of the knee treated by total replacement an average of 35 years after the primary infection. Three patients had no antituberculous prophylaxis and three had drugs for two to three weeks before and three weeks after the operation. One patient with a missed primary diagnosis had a relapse of the tuberculous arthritis 18 months after his arthroplasty and was successfully treated with antituberculous drugs for one year. At an average follow-up of 6.3 years all the patients were markedly improved. Old tuberculosis of the knee can be treated successfully with arthroplasty but there is a risk of reactivation of disease and prophylactic drugs are recommended.

We report the results of cementless total joint replacement in 18 patients with old tuberculosis of the hip, performed, on average, 34 years after the onset of infection. Mean follow-up was 3.5 years. Only seven of the patients had antituberculous drugs during or after the operation. Using the Mayo hip score, 15 patients had excellent or good results and two had a fair rating. One patient had the prosthesis removed more than one year postoperatively for late haematogenous staphylococcal infection and had a poor rating. All the patients had relief of hip-related pain. Despite the absence of any reactivation of tuberculosis in our series, we recommend the use of specific prophylaxis.

1. Experimental fracture callus in rats contains mast cells as a normal morphological element.

2. The mast cell count undergoes peculiar variations in the normal course of events in experimentally delayed or accelerated bone repair.

3. A hypothesis is presented in which the tissue mast cell granules are regarded as calcium transporters in the mineral phase of callus formation, a process probably corresponding to Selye's concept of "mastocalciphylaxis" and "mastocalcergy."