DOES THE USE OF TAPER-SLIP CEMENTED STEM REDUCE PERIPROSTHETIC FRACTURE RISK WITH THE ANTERIOR APPROACH? A CASE-CONTROL STUDY

Periprosthetic fracture (PPF) risk post-THA with uncemented, short stems, is increased with the anterior approach (AA). Whether cemented stems reduce this risk is unknown. This study aims to 1. Assess whether use of a cemented stem with the AA reduces PPF-risk; and 2. Identify factors that influence outcome when using a cemented stem. This is a retrospective, consecutive, multi-surgeon, case-control study from an academic center. The first 100 hybrid THAs (cases) with a taper-slip cemented stem, inserted with the AA were studied (69% females; age:74±10 years-old; BMI:26±5). Controls comprised of 200 uncemented THAs with a short, uncemented stem, performed by the same arthroplasty surgeons, prior to introduction of the cemented stem. Cases and controls were matched for patient factors known to influence fracture risk: age, gender, BMI, diagnosis, femoral- (DORR-type; canal-flare index) and pelvic- (ilioischial ratio, ASIS-GT distance) morphologies. Outcomes of interest included: PPF-risk, stem subsidence, quality of cementation (optimum: Barrack-cementation grades: A/B or suboptimum: Barrack-cementation grades: C/D). At minimum 1-year follow-up, there were 11 PPFs (3.6%). There was no difference in PPF-risk between cemented (4/100; 2xVancouver-A; 2xVancouver-B2) and uncemented stems (7/200; 1xVancouver-A; 1xVancouver-B1; 5xVancouver-B2) (p=0.9). Suboptimum cementation was seen in 15 hips (15%); two of which fractured (Vancouver-B2; risk-ratio:27; p=0.03) and one subsided. Hips with suboptimum cementation had lower ASIS-GT distance (88±15 vs. 101±15; p=0.004); lower canal-flare-index (3.2±0.5 vs. 3.7±0.7; p=0.015) and higher canal-calcar-ratio (0.54±0.08 vs. 0.47±0.08; p=0.005) compared to optimally cemented hips. Use of a taper-slip cemented stem is not associated with reduced PPF risk following AA-THA. Vancouver B2 and subsidence were only seen with suboptimal cementation. Suboptimum cementation was associated the narrow operative window (short ASIS-GT distance), which reduces the ability to adequately insert and pressurize cement, especially in capacious femurs, using current equipment (rigid/long) that do not favor cementation with the AA.