Cementless prosthesis of the hip joint with "spongy metal" surface. A prospective study.

Our investigations in human specimens and animal experiments show that prostheses with a spongy metal surface can become fixed by bony ingrowth to varying degrees. After consistent clinical and radiological follow-up over 12-65 months (mean 34 months) in a prospective study of 100 consecutive patients in whom 106 cementless total hip replacements had been carried out, we were able to show that after 1 year 82% of patients were pain-free with the prosthesis fixed by bony ingrowth, 8% were pain-free with the prosthesis fixed by dense fibrous tissue and 10% were not pain-free, but did not want revision surgery. Thigh pain decreased steadily from 53% 3 months postoperatively to 6.6% 15 months after operation. We believe that, when the implantation technique is exact, a high percentage of cementless spongy metal prostheses are fixed by bony ingrowth, and that a cementless prosthesis should be implanted only in patients under 60 years of age without osteoporosis.