The Effect of Surgical Technique on Cement Mantle Strength in Total Hip Arthroplasty

Abstract

A tapered aluminium model was designed to simulate the internal geometry of the reamed femoral medullary cavity. The surface of the model was coated with blood and then polymethylmethacrylate cement (Simplex P, Howmedica UK) was inserted retrograde, prograde, prograde with a venting tube, prograde with a perforated distal cement restrictor, all with a cement gun; and manually by thumbing with a venting tube. Casts were examined radiographically, weighed, measured and tested to failure in compression. Using the same cementing techniques, both concentric and eccentric mantles were produced by insertion of a prosthesis, with or without spacers, and tested to failure in hoop tension. Cast weight correlated with cement strength per unit weight and volume. Casts produced by the retrograde technique were heaviest and those produced by prograde with a venting and thumbed mantles the weakest. Concentric mantles were stronger than eccentric. Incomplete spacers ensured concentricity but weakened the mantle such that no benefit was gained. Complete precast spacers also ensured concentricity and a minimum mantle thickness but did not compromise mantle strength. The best method of inserting cement in the femur during total hip arthroplasty is retrograde with a complete precast spacer.