[Experimental study of cementless fixation of pearl-surfaced hip arthroplasties]

Femoral head replacement with pearl-surfaced prosthesis was performed on one side of each of 33 mongrel dogs. 30 of the implants inserted were without cement fixation while the other 3 with for comparison. The specimens were taken out in times of 2 weeks, 1,2,4,6, and 8 months after implantation for radiologic, histologic and biomechanical studies. In 2 weeks' specimens, quite an amount of new bone tissues were found in the interspaces among the pearls on the surface of the prosthesis; by the end of the first month, the interspaces were full of new bone, commencing lamination and progressing to become denser and denser up to 2 months when it appeared as dense as that of cortex. Biochemically the combination strength in the cementless group as a rule, was stronger than that in the control group. Some specimens, the portion in which the prosthetic stem had been embedded, were equally divided into 3 segments, upper middle and lower, to measure the combination strength at different sites. The tested values showed that the strength ratio was 4:2:1 corresponding to the upper, middle and lower segment. It is convincible that the pearl-surfaced hip prosthesis provides reliable stability without cement and it could be safely applied in clinical use.