EFFECTS OF LAMINATION ON THE STRENGTH OF BONE-CEMENT

To improve cement penetration into the cancellous bone of the acetabul um in hip arthroplasty, sequential cementation of each anchoring hole may be feasible. Since this procedure creates laminations in the cemen t, we have determined the conditions under which such laminations affe ct the strength of the cement. Cement bars made at 2, 3 or 4 minutes a fter the start of cement mixing and with either dry laminations or lam inations including blood or saline were tested for tensile strength. S olid unlaminated bars were used as references. Dry and saline laminati ons made up to 4 minutes after the start of cement mixing did not redu ce the strength of the cement. However, there was a time-dependent dec rease in cement strength if blood was entrapped in the interface. In s uch cases, there was a decrease in strength for laminations made at 4 minutes, at 3 minutes this was less pronounced and at 2 minutes no wea kening at all was noted. Our findings indicate that a sequential cemen tation procedure is permissible as regards cement strength, provided i t is performed within 2-3 minutes after the start of cement mixing. If the cement area is kept free from blood, the time may be prolonged up to 4 minutes, without the risk of weakening the cement strength.