Modular Versus Monoblock Cementless Acetabular Cups in Primary Total Hip Arthroplasty- A Review

Abstract

AIM: The evolution of cup designs have indeed contributed to better long term results in hip arthroplasty. This article aims to address the evolution of the modern day cups, pros and cons,literature review with regards to outcome and survivorship of monoblock and modular cementless cups in primary total hip arthroplasty. Methods: We conducted a systematic literature search on Pubmed,Medline and Cochrane database and enlisted Randomised Controlled trials (Level 1/II evidence)/Retrospective comparative study, (level III evidence) and case series (Level IV evidence) of Modular and Monoblock cups over the past 15 years from Jan 1998 to May 2013. Details with reference to cup revision, aseptic loosening, osteolysis, migration, liner wear and survivorship were enlisted. Results: Modular acetabular cups have shown excellent long term results in majority of the studies. Issues of liner breakage and liner dissociation have largely been resolved by the evolution of third generation cups with improved locking mechanism. Concerns of aseptic loosening and retroacetabular osteolysis prevail especially in the second decade. Monoblock cups have shown excellent results in most of the studies largely in the midterm followup. Conclusion: Both Modular and monoblock cups have shown consistent good results. Literature review has shown a paucity of Level 1 studies in this regard and more Randomised controlled trials are to be called for. As of this day there is no evidence to demonstrate a clear advantage of use of one over the other.