Early migration characteristics of a 180° porous-coated cup with 1-mm press fit
- 464 Downloads
Evaluation of early cup movement is an important diagnostic tool to predict the likelihood of long-term implant loosening and clinical failure. The investigated cementless cup is clinically proven over 10 years, but there is a paucity of information that accurately describes the migration characteristics of this component.
Materials and methods
We retrospectively analysed the clinical outcome and migration behaviour of 60 Pinnacle 100 shells after an average 3.8-year follow-up (range 2.1–5.4 years). For migration measurement, EBRA (Einzel-Bild-Röntgen-Analyse) digital software was applied. Clinical assessment was performed using the HHS, the UCLA score and the SF-36 health survey.
The clinical outcome showed excellent results with a mean HHS of 95.4 (SD 7.1) and mean UCLA of 6.9 (SD 1.3). All implants were radiologically stable within the observation period and none of the cups was at risk for aseptical loosening. EBRA analysis revealed a mean total migration of 1.4 mm (SD 0.9) (95 % CI 1.1–1.6) at 3 years. Eight cups migrated more than 1 mm within the first three postoperative months, thereafter the migration curves flattened down.
Surgeons may expect to find a variable amount of early migration when using the Pinnacle cup. To our knowledge, these are the first results, which show an early “impaction” of a cementless cup, followed by subsequent osseointegration. We believe that an appropriate long-term outcome of the investigated cup is ensured. The data of the present investigation will provide clinicians with useful baseline information with which to compare new cup designs.
KeywordsTotal hip arthroplasty Cementless Migration analysis EBRA
The study was designed and performed as an academic investigation without any external or industrial funding sources.
Conflict of interest
The authors declare that they have no conflict of interest.
- 1.NJRfEaW (2011) National Joint Registry for England and Wales 8th Annual Report http://www.njrcentre.org.uk/NjrCentre/Portals/0/Documents/NJR%208th%20Annual%20Report%202011.pdf
- 9.Krismer M, Stockl B, Fischer M, Bauer R, Mayrhofer P, Ogon M (1996) Early migration predicts late aseptic failure of hip sockets. J Bone Jt Surg Br 78:422–426Google Scholar
- 10.Stocks GW, Freeman MA, Evans SJ (1995) Acetabular cup migration. Prediction of aseptic loosening. J Bone Jt Surg Br 77:853–861Google Scholar
- 17.Harris WH (1969) Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Jt Surg Am 51:737–755Google Scholar