Inferior stability of a biodegradable cement plug

Introduction: Modern cementing technique demands high intramedullar cement pressure to create an optimum fixed cement support of the femoral stem. Pressure resistant, stable closure of the canal therefore is absolutely necessary. Biodegradable cement restrictors, if corresponding to above mentioned attributes, could be of immense advantage in case of potential revision surgery. Material and methods: A prospective, randomized trial was performed on a consecutive series of 130 patients who underwent primary cemented total hip arthroplasty due to hip arthrosis to compare a degradable cement restrictor and a non-degradable cement restrictor in their ability to resist distal migration during stem insertion. Results: The median cement plug length measured 27 mm (range −12 to 126 mm, 95% confidence interval (CI) 20–33 mm) in the biodegradable restrictor group and 15 mm (range 0–61 mm, 95% CI 12–18 mm) in the non-degradable restrictor group (P=0.003). A significant effect of the relationship between the difference of restrictor size and the diameter of the femoral canal on length of cement distal of the tip of the stem in between the two groups was evident (P=0.031). Conclusion: The results indicate insufficient intramedullary plug fixation of the degradable restrictor probably due to the elastic material properties which also may lead to inferior precision in restrictor size choice.