Recent advances in polyethylene and ceramic technologies has allowed us to use larger size heads without compromising the wear properties of a THR. One benefit of this change has been proposed to be a lower incidence of dislocation. This is a retrospective study looking at the effect of using large heads in our patient population. We retrospectively evaluated the dislocation rate in 913 THR's performed using the same standardized surgical technique employed by a single team of surgeons at our institution between 1995 and 2015. Patients were assigned to two groups: small (28 mm and smaller) (SH), large diameter heads (36 mm and larger) (LH). The cup position was measured and plotted to determine its status according to the Lewinnek safe zone (15°±10° for anteversion, 40°±10° for inclination). Sixteen of the 472 SH dislocated (3.4 percent) while 5 of the 441 LH group (1.1 percent) (P=0.04). In all of the LH patients that dislocated the cup position was in the safe range of Lewinnek. However, in the LH group only 65 percent of the cups were in the safe zone. Using the same surgical approach by changing the head size to 36 mm and larger, we were able decrease the dislocation rate significantly. Errors of cup positioning according to Lewinnek became oblivious when using large heads compared to small heads. In our opinion, using large heads in total hip arthroplasty makes a difference in terms of dislocation

Aims

The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA).

Aims

Studying the indications for revision total hip arthroplasty (THA) may enable surgeons to change their practice during the initial procedure, thereby reducing the need for revision surgery. The aim of this study was to identify and describe the potentially avoidable indications for revision THA within five years of the initial procedure.

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: Bone Joint J 2015;97-B:10–18.

There is a high rate of mortality in elderly patients who sustain a fracture of the hip. We aimed to determine the rate of preventable mortality and errors during the management of these patients. A 12 month prospective study was performed on patients aged > 65 years who had sustained a fracture of the hip. This was conducted at a Level 1 Trauma Centre with no orthogeriatric service. A multidisciplinary review of the medical records by four specialists was performed to analyse errors of management and elements of preventable mortality. During 2011, there were 437 patients aged > 65 years admitted with a fracture of the hip (85 years (66 to 99)) and 20 died while in hospital (86.3 years (67 to 96)). A total of 152 errors were identified in the 80 individual reviews of the 20 deaths. A total of 99 errors (65%) were thought to have at least a moderate effect on death; 45 reviews considering death (57%) were thought to have potentially been preventable. Agreement between the panel of reviewers on the preventability of death was fair. A larger-scale assessment of preventable mortality in elderly patients who sustain a fracture of the hip is required. Multidisciplinary review panels could be considered as part of the quality assurance process in the management of these patients.

Cite this article: Bone Joint J 2014;96-B:1178–84.

Aims

The aim of this study was to evaluate the accuracy of implant placement when using robotic assistance during total hip arthroplasty (THA).

Ideal placement of the acetabular component remains elusive both in terms of defining and achieving a target. Our aim is to help restore original anatomy by using the transverse acetabular ligament (TAL) to control the height, depth and version of the component. In the normal hip the TAL and labrum extend beyond the equator of the femoral head and therefore, if the definitive acetabular component is positioned such that it is cradled by and just deep to the plane of the TAL and labrum and is no more than 4mm larger than the original femoral head, the centre of the hip should be restored. If the face of the component is positioned parallel to the TAL and psoas groove the patient specific version should be restored. We still use the TAL for controlling version in the dysplastic hip because we believe that the TAL and labrum compensate for any underlying bony abnormality.

The TAL should not be used as an aid to inclination. Worldwide, > 75% of surgeons operate with the patient in the lateral decubitus position and we have shown that errors in post-operative radiographic inclination (RI) of > 50° are generally caused by errors in patient positioning. Consequently, great care needs to be taken when positioning the patient. We also recommend 35° of apparent operative inclination (AOI) during surgery, as opposed to the traditional 45°.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):37–43.

There have been considerable recent advances in the understanding and management of femoroacetabular impingement and associated labral and chondral pathology. We have developed a classification system for acetabular chondral lesions. In our system, we use the six acetabular zones previously described by Ilizaliturri et al. The cartilage is then graded on a scale of 0 to 4 as follows: grade 0, normal articular cartilage lesions; grade 1, softening or wave sign; grade 2, cleavage lesion; grade 3, delamination; and grade 4, exposed bone. The site of the lesion is further classed as A, B or C based on whether the lesion is less than one-third of the distance from the acetabular rim to the cotyloid fossa, one-third to two-thirds of the same distance and greater than two-thirds of the distance, respectively. In order to validate the classification system, six surgeons graded ten video recordings of hip arthroscopy.

Our findings showed a high intra-observer reliability of the classification system with an intraclass correlation coefficient of 0.81 and a high interobserver reliability with an intraclass correlation coefficient of 0.88.

We have developed a simple reproducible classification system for lesions of the acetabular cartilage, which it is hoped will allow standardised documentation to be made of damage to the articular cartilage, particularly that associated with femoroacetabular impingement.

The purpose of this study was to define immediate post-operative ‘quality’ in total hip replacements and to study prospectively the occurrence of failure based on these definitions of quality. The evaluation and assessment of failure were based on ten radiological and clinical criteria. The cumulative summation (CUSUM) test was used to study 200 procedures over a one-year period. Technical criteria defined failure in 17 cases (8.5%), those related to the femoral component in nine (4.5%), the acetabular component in 32 (16%) and those relating to discharge from hospital in five (2.5%). Overall, the procedure was considered to have failed in 57 of the 200 total hip replacements (28.5%). The use of a new design of acetabular component was associated with more failures. For the CUSUM test, the level of adequate performance was set at a rate of failure of 20% and the level of inadequate performance set at a failure rate of 40%; no alarm was raised by the test, indicating that there was no evidence of inadequate performance.

The use of a continuous monitoring statistical method is useful to ensure that the quality of total hip replacement is maintained, especially as newer implants are introduced.

The computed neck-shaft angle and the size of the femoral component were recorded in 100 consecutive hip resurfacings using imageless computer-navigation and compared with the angle measured before operation and with actual component implanted. The reliability of the registration was further analysed using ten cadaver femora. The mean absolute difference between the measured and navigated neck-shaft angle was 16.3° (0° to 52°). Navigation underestimated the measured neck-shaft angle in 38 patients and the correct implant size in 11. Registration of the cadaver femora tended to overestimate the correct implant size and provided a low level of repeatability in computing the neck-shaft angle.

Prudent pre-operative planning is advisable for use in conjunction with imageless navigation since misleading information may be registered intraoperatively, which could lead to inappropriate sizing and positioning of the femoral component in hip resurfacing.