In order to prevent dislocation of the hip after total hip arthroplasty
(THA), patients have to adhere to precautions in the early post-operative
period. The hypothesis of this study was that a protocol with minimal
precautions after primary THA using the posterolateral approach
would not increase the short-term (less than three months) risk
of dislocation. We prospectively monitored a group of unselected patients undergoing
primary THA managed with standard precautions (n = 109, median age
68.9 years; interquartile range (IQR) 61.2 to 77.3) and a group
who were managed with fewer precautions (n = 108, median age 67.2
years; IQR 59.8 to 73.2). There were no significant differences between
the groups in relation to predisposing risk factors. The diameter
of the femoral head ranged from 28 mm to 36 mm; meticulous soft-tissue
repair was undertaken in all patients. The medical records were
reviewed and all patients were contacted three months post-operatively
to confirm whether they had experienced a dislocation. Aims
Patients and Methods
The aim of this study was to establish the natural
course of unrevised asymptomatic pseudotumours after metal-on-metal
(MoM) hip resurfacing during a six- to 12-month follow-up period.
We used repeated metal artefact reduction sequence (MARS)-magnetic
resonance imaging (MRI), serum metal ion analysis and clinical examination to
study 14 unrevised hips (mean patient age 52.7 years, 46 to 68,
5 female, 7 male) with a pseudotumour and 23 hips (mean patient
age 52.8 years, 38 to 69, 7 female, 16 male) without a pseudotumour.
The mean post-operative time to the first MARS-MRI scan was 4.3 years
(2.2 to 8.3), and mean time between the first and second MARS-MRI scan
was eight months (6 to 12). At the second MRI scan, the grade of
severity of the pseudotumour had not changed in 35 hips. One new
pseudotumour (Anderson C2 score, moderate) was observed, and one
pseudotumour was downgraded from C2 (moderate) to C1 (mild). In
general, the characteristics of the pseudotumours hardly changed. Repeated MARS-MRI scans within one year in patients with asymptomatic
pseudotumours after MoM hip resurfacing showed little or no variation.
In 23 patients without pseudotumour, one new asymptomatic pseudotumour
was detected. This is the first longitudinal study on the natural history of
pseudotumours using MARS-MRI scans in hip resurfacing, and mirrors
recent results for 28 mm diameter MoM total hip replacement. Cite this article:
Hip resurfacing arthroplasty (HRA) has seen a recent revival with third generation Metal-on-Metal prostheses and is now widely in use. However, safety and effectiveness of hip resurfacing are still questioned. We systematically reviewed peer-reviewed literature on hip resurfacing arthroplasty to evaluate implant survival and functional outcomes of hybrid Metal-on-Metal hip resurfacing Arthroplasty. Electronic databases and reference lists were searched from 1988 to September 2009. Identified abstracts were checked for inclusion or exclusion by two independent reviewers. Data were extracted and summarized by one reviewer and verified by a second reviewer. Main study endpoint was implant survival, which we compared with the National Institute of Clinical Excellence (NICE) benchmark. We also evaluated radiological and functional outcomes, failure modes and other adverse events.Introduction
Method
We systematically reviewed the peer-reviewed literature to relate the survival of hybrid metal-on-metal hip resurfacing arthroplasty devices to a National Institute of Clinical Excellence (NICE) benchmark for choosing a primary total hip replacement, which is a survival rate of 90% at a follow-up of ten years. A total of 29 articles (10 621 resurfaced hips) met the inclusion criteria. The mean follow-up ranged from 0.6 to 10.5 years and the survival of the implant ranged from 84% to 100%. Of the 10 621 hips, 370 were revised (3.5%), with aseptic loosening as the most frequent mode of failure. None of the hip resurfacing arthroplasty implants used to date met the full ten-year NICE benchmark of survival. A total of 13 studies showed satisfactory survival compared with the three-year NICE benchmark.
