The Impact of Trabecular Metal on Hip Centre of Rotation in Revision and Complex Primary Hip Arthroplasty, a Radiological Review

• Published in: Hip international 2017-09, Vol.27 (5), p.500-504
• Main Authors: O'Brien, Carl, Keogh, Cillian J., Hannigan, Ailish, Brennan, Stephen, Kennedy, Cian, Gul, Rehan, Harty, James A.
• Format: Article
• Language: English
• Subjects: Acetabulum - diagnostic imaging; Acetabulum - surgery; Aged; Arthroplasty, Replacement, Hip - methods; Cohort Studies; Female; Hip Prosthesis; Humans; Male; Metals; Middle Aged; Prosthesis Design; Radiography - methods; Reoperation; Retrospective Studies
• ISSN: 1120-7000; 1724-6067
• DOI: 10.5301/hipint.5000503

Introduction Total hip arthroplasty (THA) is a very successful procedure. Revision THA is becoming increasingly common. Recent developments to improve outcomes include the development of large trabecular metal (TM) acetabular cups and augments. There is a paucity of data on the benefit of these new techniques. Methods A single-centre retrospective review consisting of a radiological review of post-op revision THA anteroposterior pelvis. Data collection was performed using the Irish National Orthopaedic Register (INOR) and from a previous project. We used a technique developed by Fessy et al in 1999 to measure the centre of rotation (COR) of the hip. We then compared our study to that of a study measuring the COR of healthy native hips. Results 127 revision THA analysed. Native COR calculated by Fessy et al showed a mean horizontal (x) axis 33.6 mm (standard deviation [SD] 5.74) and a vertical (y) axis 16.4 mm (SD 4.67). Non-TM revisions showed a mean x axis of 29 mm (SD 3.9) and y axis 17.9 (SD 5.9). TM Augments had a mean x axis 29.2 mm (SD 7.9) and y axis of 21.5 (SD 8.4). TM Cups alone had a mean x axis 27 mm (SD 6.9) and y axis 22 mm (SD 10.18). Conclusions COR of TM implants showed considerable deviation from the norm. Non-TM implants showed a COR within acceptable physiological range. TM components consistently failed to restore a natural COR in our cohort. The implications of this remain uncertain but must be considered in any decision to use TM.