Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty

Abstract

BackgroundThe preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.Materials and methodsForty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4–11 years).ResultsThere were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.ConclusionsAlthough optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.

Reconstruction options and outcomes for acetabular bone loss in revision hip arthroplasty

“…Advantages of un uncemented hemispherical cup are a stable and biologic fixation in mild-to-moderate bone defects and a surgical technique familiar to many arthroplasty surgeons; however, it is accepted that provide poor results in severe acetabular bone defects (>50% of bone stock). 51 …”

“… 55 , 56 Oblongs cups adapt better to large and oblong bone defects, that cannot be filled with hemispherical cups, avoiding marked reaming of the anterior and posterior columns. 51 , 55-61 Three types of Oblong Cups have been described: the bilobed oblong acetabular component, the longitudinal oblong revision cup (LOR) and the BOFOR cup. 56 In a recent systematic review, Volpin et al , 11 reported good results for oblong cups in term of overall failure rate (5.9%, 12 of 203 hips) with an aseptic loosening rate of 3.9% (8 of 203 hips) and a dislocation rate of 2.4% (5 of 203 hips) at a mean follow-up of 7.6 years.…”

“…These results are probably due to the ability of these cups to restore the hip center and achieve osseointegration through sufficient bone implant contact. 51 The main advantage of the cups is their relative ease of implantation and the oblong shape that almost enables a press-fit incorporation.…”

Bone Defect Determines Acetabular Revision Surgery

“…Oblong uncemented cups are an option for revision surgery, but care must be taken in major acetabular bone defects. Cup stability is one of the concerns in different series, although acetabular reconstruction close to the approximate true centre of the femoral head may improve clinical results (9).…”

Azetabuläre Revision: Rekonstruktion kavitärer und segmentaler Defekte unter besonderer Berücksichtigung modularer hoch poröser Pfannensysteme

“…Hierbei überbrückt der Ring den knöchernen Defekt, schützt eine defektfüllende Knochenplastik und ermöglicht somit deren Umbau in nativen Knochen[30]. In einer Studie an 50 azetabulären Revisionen mit allogenen, vorwiegend strukturellen Transplantaten, die durch einen Ring geschützt waren und bei denen eine spätere Revision notwendig wurde, berichteten die Autoren über eine Transplantatintegration in 31 Fäl-Die Präparation des Implantatlagers ist als eher schwierig einzustufen, besonders zu achten ist auf den Erhalt des mechanisch tragenden autochthonen Restknochens während der Präparation, um eine stabile Implantatfixierung zu erreichen[35,36]. Es liegen derzeit wenige Ergebnisse mit eher inhomogener Überlebensrate vor.…”