Abstract
Aseptic loosening of the acetabular component is the major long-term complication of cemented total hip arthroplasty (THA). Failure of the acetabular cup occurs two to three times more frequently than failure of the femoral component. Third generation cementing techniques have improved the longevity of cemented components in THA. Although suction venting of the femoral shaft is a well-recognised practice, venting of the acetabulum during the cementing process has been little studied. This prospective study sets out to evaluate the effect of iliac wing vacuum aspiration on cement penetration of the acetabulum. Forty patients (Male 18, Female 22) aged 19–82 years (average 67+12 years) undergoing primary THA were entered consecutively into two study groups (20 hips per group). Reasons for THA included osteoarthritis (35) acetabular Dysplasia (2), rheumatoid arthritis (1), perthes (1) and conversion THA post dynamic screw (1)> A single consultant surgeon performed all procedures in a standard operating room with laminar flow. A posterior approach was used in all hips. Third generation cementing techniques were used for acetabular component insertion. Twenty-six millimetres internal diameter Charnley ogee LPW polyethylene cups (Depuy) with varying external diameters [43 mm (9), 47 mm (24), 50 mm (5) and 53 mm (3)] were used and implanted with “Simplex” polymethylmethacrylate cement (Howmedica). Group 1 underwent acetabular cement pressurisation for sixty seconds prior to insertion of cup. Group 2 underwent pressurisation with simultaneous vacuum suction of the ipsilateral ilium using an Exeter iliac wing aspirator. Pre-and post-operative haemoglobin values were recorded for all patients. Standard post-operative radiographs were reviewed blindly to assess penetration of cement. A custom-made template facilitated measurement of depth (mm) of cement penetration in three areas corresponding with Delee-Charnley acetabular zones. Cement penetration was enhanced in all zones following iliac wing vacuum aspiration. The effect of venting was statistically significant (zone I 21.1+6.4mm v 12.8+2.8mm. zone II 7.0+2.4mm v 5.5+2.0mm, zone III 5.3+2.4mm v 4.2+1.4mm). The bone cement mantle interface was also completely obliterated following iliac wing aspiration.
The abstracts were prepared by Raymond Moran. Correspondence should be addressed to him at the Irish Orthopaedic Assocation, c/o Cappagh National Orthopaedic Hospital, Finglas, Dublin 11, Ireland.
