Acetabular edge-loading was a cause of increased wear rates in metal-on-metal hip arthroplasties, ultimately contributing to their failure. Although such wear patterns have been regularly reported in retrieval analyses, this study aimed to determine their in vivo location and investigate their relationship with acetabular component positioning. 3D CT imaging was combined with a recently validated method of mapping bearing surface wear in retrieved hip implants. The asymmetrical stabilizing fins of Birmingham hip replacements (BHRs) allowed the co-registration of their acetabular wear maps and their computational models, segmented from CT scans. The in vivo location of edge-wear was measured within a standardized coordinate system, defined using the anterior pelvic plane.Aims
Methods
The main advantage of 3D-printed, off-the-shelf acetabular implants is the potential to promote enhanced bony fixation due to their controllable porous structure. In this study we investigated the extent of osseointegration in retrieved 3D-printed acetabular implants. We compared two groups, one made via 3D-printing (n = 7) and the other using conventional techniques (n = 7). We collected implant details, type of surgery and removal technique, patient demographics, and clinical history. Bone integration was assessed by macroscopic visual analysis, followed by sectioning to allow undecalcified histology on eight sections (~200 µm) for each implant. The outcome measures considered were area of bone attachment (%), extent of bone ingrowth (%), bone-implant contact (%), and depth of ingrowth (%), and these were quantified using a line-intercept method.Aims
Methods
The optimum clearance between the bearing surfaces of hip arthroplasties is unknown. Theoretically, to minimize wear, it is understood that clearances must be low enough to maintain optimal contact pressure and fluid film lubrication, while being large enough to allow lubricant recovery and reduce contact patch size. This study aimed to identify the relationship between diametrical clearance and volumetric wear, through the analysis of retrieved components. A total of 81 metal-on-metal Pinnacle hips paired with 12/14 stems were included in this study. Geometrical analysis was performed on each component, using coordinate and roundness measuring machines. The relationship between their as-manufactured diametrical clearance and volumetric wear was investigated. The Mann-Whitney U test and unpaired Aims
Methods
The use of ceramic femoral heads in total hip arthroplasty (THA) has increased due to their proven low bearing wear characteristics. Ceramic femoral heads are also thought to reduce wear and corrosion at the head-stem junction with titanium (Ti) stems when compared with metal heads. We sought to evaluate taper damage of ceramic compared with metal heads when paired with cobalt chromium (CoCr) alloy stems in a single stem design. This retrieval study involved 48 total hip arthroplasties (THAs) with CoCr V40 trunnions paired with either CoCr (n = 21) or ceramic (n = 27) heads. The taper junction of all hips was evaluated for fretting/corrosion damage and volumetric material loss using a roundness-measuring machine. We used linear regression analysis to investigate taper damage differences after adjusting for potential confounding variables.Objectives
Methods
The aim of this study was to compare the design of the generic
OptiStem XTR femoral stem with the established Exeter femoral stem. We obtained five boxed, as manufactured, implants of both designs
at random (ten in total). Two examiners were blinded to the implant
design and independently measured the mass, volume, trunnion surface
topography, trunnion roughness, trunnion cone angle, Caput-Collum-Diaphyseal
(CCD) angle, femoral offset, stem length, neck length, and the width
and roughness of the polished stem shaft using peer-reviewed methods.
We then compared the stems using these parameters.Aims
Materials and Methods
The National Joint Registry for England, Wales and Northern Ireland
(NJR) has extended its scope to report on hospital, surgeon and
implant performance. Data linkage of the NJR to the London Implant
Retrieval Centre (LIRC) has previously evaluated data quality for
hip primary procedures, but did not assess revision records. We analysed metal-on-metal hip revision procedures performed
between 2003 and 2013. A total of 69 929 revision procedures from
the NJR and 929 revised pairs of components from the LIRC were included.Aims
Methods
Arthroplasty registries are important for the
surveillance of joint replacements and the evaluation of outcome. Independent
validation of registry data ensures high quality. The ability for
orthopaedic implant retrieval centres to validate registry data
is not known. We analysed data from the National Joint Registry
for England, Wales and Northern Ireland (NJR) for primary metal-on-metal
hip arthroplasties performed between 2003 and 2013. Records were
linked to the London Implant Retrieval Centre (RC) for validation.
A total of 67 045 procedures on the NJR and 782 revised pairs of
components from the RC were included. We were able to link 476 procedures
(60.9%) recorded with the RC to the NJR successfully. However, 306
procedures (39.1%) could not be linked. The outcome recorded by the
NJR (as either revised, unrevised or death) for a primary procedure
was incorrect in 79 linked cases (16.6%). The rate of registry-retrieval
linkage and correct assignment of outcome code improved over time.
The rates of error for component reference numbers on the NJR were
as follows: femoral head category number 14/229 (5.0%); femoral head
batch number 13/232 (5.3%); acetabular component category number
2/293 (0.7%) and acetabular component batch number 24/347 (6.5%). Registry-retrieval linkage provided a novel means for the validation
of data, particularly for component fields. This study suggests
that NJR reports may underestimate rates of revision for many types
of metal-on-metal hip replacement. This is topical given the increasing
scope for NJR data. We recommend a system for continuous independent
evaluation of the quality and validity of NJR data. Cite this article:
