Evert J. Smith

Poor reproducibility in radiographic grading of femoral cementing technique in total hip arthroplasty

The first study of the reproducibility of a widely accepted grading system for femoral cementation in total hip arthroplasty is reported. Sixty postoperative radiographs were graded on two occasions at least 2 weeks apart by two experienced observers. The test-retest reproducibility rate was 60% for observer 1 and 70% for observer 2. The interobserver reproducibility varied between 60 and 63% for the different assessments. Between 5 and 6% of cases differed by more than one grade between tests. Kappa statistical analysis confirmed that reproducibility was poor in all cases. This cement grading system, even in the hands of experienced observers, has too high a rate of intraobserver and interobserver error to recommend its use.

Subsidence of the stem after impaction bone grafting for revision hip replacement using irradiated bone

Loss of bone stock is a major problem in revision surgery of the hip. Impaction bone grafting of the femur is frequently used when dealing with deficient bone stock. In this retrospective study a consecutive series of 68 patients (69 hips) who had revision of a hip replacement with femoral impaction grafting were reviewed. Irradiated bone allograft was used in all hips. Radiological measurement of subsidence of the stem, incorporation of the graft and remodelling was carried out and showed incorporation of the graft in 26 of 69 hips (38%). However, there was no evidence of trabecular remodelling. Moderate subsidence of 5 mm to 10 mm occurred in ten hips (14.5%), and massive subsidence of > 10 mm in five (7.2%). The results of this study are less favourable than those of others describing studies of revision of the femoral stem using impaction bone grafting. The absence of the characteristic changes of graft remodelling noted in other series raises the question as to whether irradiated bone graft may be a significant factor influencing the post-operative outcome.

The crescent sign: dissociation of the polyethylene liner from a modular acetabular component in total hip arthroplasty

ObjectiveTo study whether there was a common pattern of clinical symptoms, signs and radiographic features for the dissociation of the polyethylene liner from an acetabular component and to postulate reasons for these features.Design and patientsRetrospective study of notes and radiographs of cases of revision hip arthroplasty for polyethylene liner dissociation of the cementless Harris–Galante I porous-coated acetabular component (Zimmer Inc, Warsaw, IN) at the Avon Orthopaedic Centre, Bristol, UK and St. Mary’s Hospital, Bristol, UK between 1995 and 2004. Patients were contacted to confirm preoperative symptoms.ResultsNine cases of late polyethylene liner dissociation of this prosthesis have been revised in these institutions. All patients presented with a reduction in mobility, groin pain and limp. Eight patients reported an audible noise on hip movement. In all cases, radiographs showed radiolucency medial to the femoral neck in association with an eccentrically placed femoral head showing contact with the acetabular metal shell, which we have termed the “crescent sign.”ConclusionsThere is a typical clinical presentation in this study. The diagnosis can be made from a single anteroposterior pelvic radiograph without the need for previous films for comparison, or the need for arthrography. Clinicians should look specifically for the crescent sign when an eccentrically placed femoral head has been noted, in order to differentiate the more unusual diagnosis of dissociation from that of polyethylene wear. Early revision surgery can prevent damage to the femoral head and metal acetabular shell, thus reducing the complexity of revision surgery.

Resurfacing hip replacement - An audit of activity in the United Kingdom 2002-2003

The level of use of resurfacing hip replacement (RHR) and specific training undertaken was previously unknown in the United Kingdom. Consultant orthopaedic surgeons were audited by postal questionnaire regarding their RHR activity, training undertaken and evidence of specialisation in hip arthroplasty. RESULTS 19% of surgeons had performed RHR in the previous 12 months. 33% of revision hip surgeons had performed RHR. The majority of consultants performed 6-10 cases per year. 73% performed less than 20 cases per year. For training, 30% had observed RHR surgery and 23% had attended a formal course. 7.8% of those performing RHR had neither been on a course nor observed surgery. Both British Hip Society membership and the completion of a hip fellowship were associated with the frequency of RHR . Those who had completed previous hip fellowship or were BHS members performed significantly more RHR. CONCLUSIONS RHR is currently performed by specialists. The level of use is increasing rapidly and the standard of implantation needs to be safeguarded in order to ensure that the current successful short term results are maintained in the long term. Given the steep learning curve, the lack of long-term outcome and concerns regarding metal-on-metal bearings, we believe that the implant should continue to be used in accordance with NICE guidelines and that implantation should be performed by surgeons with a specialist interest in hip arthroplasty and specific training. (Hip International 2004; 14: 163-8).

Mid-term results of ReCap/Magnum/Taperloc metal-on-metal total hip arthroplasty with mean follow-up of 7.1 years

Introduction Despite enthusiasm for metal-on-metal bearings, disappointing short- to mid-term outcomes has all but halted the use of this bearing articulation. This review presents mid-term results for the ReCap Magnum total hip replacement. Patients and Methods This prospective study evaluated 79 ReCap/Magnum/Taperloc total hip replacements with mean follow-up of 7.1 (range 3.7-9.2) years. 43 were female and 36 male. Metal ions were measured and radiographic measurement included a ‘margin of safety’ angle to quantify risk of edge loading. When a clinical suspicion of adverse reaction to metal debris was present, patients had metal artefact reduction sequence MRI. Harris Hip Score and Oxford Hip Score evaluated functional outcome and SF-12 and EQ-5L-5D assessed quality of life at final follow-up. Results 7 hips were revised indicating 91.1% survivorship at 7.1 years. Postoperative Harris Hip Score and Oxford Hip Score significantly improved. Females and symptomatic patients predicted increased metal ions. Margin of safety correlated with postoperative Oxford Hip Score. Symptomatic hips and positive MRI showed reduced survivorship. Conclusions Compared to more traditional bearings like metal or ceramic on polyethylene the overall outcome of this ReCap/Magnum/Taperloc study cohort is modest. It is felt that further failures will occur in this group therefore cautious interpretation of the results is justified given the potential for reduced survival outcomes.

A radiographic comparison of femoral offset after cemented and cementless total hip arthroplasty

Restoring femoral offset during total hip arthroplasty is important. Femoral offset and leg lengths are inextricably linked by the caput-collum-diaphysis (CCD) angle of the implant being used. We investigate the restoration of offset and leg lengths using the radiographs of a consecutive series of patients following implantation with either a high CCD angled cementless, or an anatomical CCD angled cemented femoral component. Although our data suggests that we are able to restore femoral offset and leg lengths using either device, we recommend additional caution when using non-anatomical high CCD angled implants.

Thirty-two millimetre heads and accelerated polyethylene wear in total hip arthroplasty

In total hip arthroplasty 32 mm heads are often used as the greater diameter is thought to contribute to improved stability. However, greater head diameter can also lead to greater volumetric wear. We compared polyethylene wear between patients with 32 mm heads and those with smaller heads. All patients who had Harris Galante1 metal-backed, uncemented cups inserted between 1986 and 1996 at our institute were annually reviewed clinically and radiographically. Accelerated polyethylene wear was noted between the fifth and seventh postoperative year in 17 out of 165 total hip replacements with 32 mm heads, but only in 21 out of 961 total hip arthroplasties with smaller femoral heads. In all 17 THRs, accelerated wear was also associated with thin polyethylene (<6 mm). This paper highlights a potentially serious problem. When 32 mm metal heads are used with uncemented cups and polyethylene liners, there is a risk of accelerated acetabular wear in patients with thin polyethylene.