Introduction

There has been almost universal adoption of highly cross-linked polyethylene as the polyethylene of choice in metal-on-polyethylene articulations in total hip replacement (THR). Although wear of conventional polyethylene has been shown to be related to periprosthetic osteolysis, the relationship between wear of highly cross-linked polyethylene and osteolysis remains uncertain. Our aim was to determine the incidence and volume of periacetabular osteolysis at a minimum of seven years following primary THR with metal on highly cross-linked polyethylene articulations.

Large articulations are increasingly being used to reduce dislocation, the most common early complication following THR. However, potential benefits of large articulations in reducing dislocation have not been proven in a well-controlled clinical trial.

The aim of our randomised controlled trial was to compare the one-year incidence of dislocation between 36 and 28 mm metal on highly cross-linked polyethylene articulations.

Patients were excluded if they had a high risk of dislocation due to, for example, abnormal anatomy, neuromuscular disease, previous infection or dislocation. Eligible patients were stratified according to a number of other factors which may influence dislocation risk, including primary or revision THR and, if primary THR, by surgeon, age, diagnosis, sex and Charnley grade. Patients were randomised intra- operatively to either a 28 or 36 mm articulation. Dislocation incidence was determined using a hip instability questionnaire and a hospital visit questionnaire. A dislocation was diagnosed if there was radiological evidence and reduction by a doctor was required. Six-hundred-and-forty-four patients undergoing primary or revision THR were entered into the study.

Overall, the incidence of dislocation at one year following THR was 5.4% with a 28 mm articulation and 1.3% with a 36 mm articulation (p=.004). Incidence in primary THR patients was 4.4% with a 28 mm articulation, compared to 0.8% with a 36 mm articulation (p=.007). Incidence in revision THR patients was 12.2% and 4.9% with 28 and 36 mm articulations, respectively. For both primary and revision THR patients, sex distribution, age and BMI of patients who dislocated were similar to those of the total samples of primary or revision patients.

This large randomised study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in THR is efficacious in reducing the incidence of dislocation in the first year following THR.

Background: Our multi-centre international randomized controlled trial compared the one-year incidence of dislocation between a 36 mm and 28 mm metal on highly cross-linked polyethylene articulation in primary and revision total hip replacement (THR).

Patients: 644 patients were entered into the study. Surgical approach was posterior in primary THR and posterior, transfemoral or transtrochanteric in revision THR. Patients were stratified according to a number of factors which may influence dislocation risk and polyethylene wear. Patients were randomized intra-operatively to either a 28 or 36 mm articulation.

Results: The 12-month incidence of dislocation was statistically significantly lower in patients undergoing THR with a 36 mm articulation than in those with a 28 mm articulation (1.3% vs 5.4%, p=.004). When primary and revision THR were examined separately, the 12-month incidence of dislocation was statistically significantly lower in patients undergoing primary THR with a 36 mm articulation than in those with a 28 mm articulation (0.8% vs 4.4%, p=.007). Of the 12 primary THR patients with a 28 mm articulation who dislocated within one year, four experienced recurrent dislocation and two were revised for dislocation. Two patients with a 36 mm articulation dislocated, one of whom experienced recurrent dislocation and was revised. The incidence of dislocation after revision THR with a 36 mm articulation was 4.9%, compared to 12.2% with a 28 mm articulation. Three of the five patients who dislocated following revision THR with a 28 mm articulation experienced recurrent dislocation and were revised within one year of surgery. Two patients dislocated following revision THR with a 36 mm articulation but neither experienced recurrent dislocation or further revision.

This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in THR is efficacious in reducing the incidence of dislocation in the first year following THR.

Early revision is an important risk factor for repeated revision and poor results after primary total hip replacement and instability is a major cause of early revision. Larger articulations with cross-linked polyethylene are proposed as a solution, but these are not without risk, including fracture of the thin polyethylene rim of the liner. The aim of our study was to examine implant-related revisions among primary total hip replacement patients with up to six year follow-up in a randomized controlled trial which compared 28 mm and 36 mm metal on highly cross-linked polyethylene articulations in total hip replacement.

557 patients undergoing primary total hip replacement were included in this study. Risk factors for dislocation and wear were controlled by stratification and patients were then randomized intra-operatively to either a 28 or 36 mm articulation.

To date, 10 hips have been revised for implant-related problems following primary total hip replacement. Seven hips with a 28 mm articulation were revised to a larger articulation because of instability. Four of these were for recurrent dislocation, one for an irreduceable first dislocation and two for subluxation. In contrast, only one patient who had undergone total hip replacement with a 36 mm articulation was revised for recurrent dislocation. One hip with a 36 mm articulation in a well-positioned cup was revised to a 32 mm articulation because of elevated lip liner fracture. Another 36 mm articulation hip was revised for acetabular component loosening.

This study shows that a 36 mm metal on highly cross-linked polyethylene articulation reduces the need for early revision for instability after primary total hip replacement. However, these benefits need to be weighed against the potential risks associated with these articulations, including rare fracture of the relatively thin poly-ethylene liner.

Large articulations using cross-linked polyethylene and other alternate bearings are increasingly being used to reduce the incidence of dislocation, the most common early complication following total hip replacement. While indirect evidence has suggested the potential benefits of a large articulation in reducing dislocation risk, this has not been proven in a well-controlled clinical trial. The primary objective of our multi-centre international randomized controlled trial was to compare the one-year incidence of dislocation between a 36 mm and 28 mm metal on highly cross-linked polyethylene articulation in primary and revision total hip replacement.

644 patients were entered into the study. Patients were stratified according to a number of factors which may influence dislocation risk, including primary or revision total hip replacement, age, sex, Charnley grade, diagnosis and stem type. Patients were randomized intra-operatively to either a 28 or 36 mm articulation.

The 12-month incidence of dislocation was statistically significantly lower in patients undergoing total hip replacement with a 36 mm articulation than in those with a 28 mm articulation (1.3% vs 5.2%, p< .05). A total of 6 dislocations occurred in the 4 patients who dislocated with a 36 mm articulation, compared to a total of 36 dislocations in the 17 patients who dislocated with a 28 mm articulation. When primary and revision THR were examined separately, the 12-month incidence of dislocation was statistically significantly lower in patients undergoing primary total hip replacement with a 36 mm articulation than in those with a 28 mm articulation (0.7% vs 4.2%, p< .05). A total of 4 dislocations occurred in two patients with a 36 mm articulation, compared to a total of 19 dislocations in 12 patients with a 28 mm articulation. The incidence of dislocation after revision total hip replacement with a 36 mm articulation was 4.8%, compared to 11.1% with a 28 mm articulation.

This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in total hip replacement is efficacious in reducing the incidence of dislocation in the first year following hip replacement.

Introduction There are currently hundreds of total hip replacement (THR) prosthesis designs in use. In practice the decision to use a THR prosthesis should be based on published long-term outcomes. This study provides a critical analysis of the literature to determine what prostheses have successful published results.

Methods The Medline (Ovid) database was searched for English text publications on primary THR published between 1975 and 2002. The search produced 12219 publications with 1400 (11.5%) reporting an incidence of revision or survivorship. Criteria for potentially successful designs were applied to the percentage of hips unrevised or survivorship data. Success was defined as less than 1% revised for any cause or less than 0.5% revised due to aseptic loosening. Using reported loss to follow-up, worst case analysis was performed to divide successful prostheses into definitely (DS), probably (PB) or possibly successful (PS).

Results Only 404 (23%) of the 1404 publications reviewed were methodologically adequate. The cemented acetabular prostheses had 39 (26.5%) reports of success (46%DS, 26%PB, 28%PS) at greater than 10 years and 80 (54%) reports of failure. The cement-less acetabular prostheses had 12 (10%) reports of success (42%DS, 42%PB, 16%PS), and 55 (46%) reports of failure. For cemented femoral prostheses 50 (30%) (62%DS, 18%PB, 20%PS) reports were successful, and 86 (51%) were failures. For cementless femoral prostheses 16 (18%) (69%DS, 25%PB, 6%PS) reports were successful and 38 (42%) were failures. Nineteen different cemented acetabular designs, and 34 different cementless acetabular designs had reports of success. For the femoral prostheses there were 27 different cemented designs and 26 different uncemented designs with reports of success. Thirty-two (18.2%) prostheses designs had reports of both success and failure, 71 (40%) had reports of failure only and 73 (41.5%) had reports of success only. It was not possible to identify what design alterations, if any, were attributed to a prosthesis being classified as both a success and a failure, because the technical details of the prosthesis were often not reported.

Conclusions Only 22% of prostheses reported were successful at greater than 10 years. High loss to follow-up meant only 56% of the potentially successful prostheses were definitely successful. The reporting of prosthesis manufacturer and catalogue numbers, and the publication of good and poor results are recommended to better gauge the success of designs.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.

The purpose of health outcomes monitoring is to assess the benefits and risks of health care processes, to enable benchmarking and to allow comparative studies of new technologies and variations in clinical practice. This paper critically reviews the discipline of health outcomes monitoring in joint replacement surgery. We reviewed over 250 papers published over the last 20 years in the major English speaking journals were reviewed. We conclude that there are considerable shortcomings of clinical studies which make it difficult to determine the results of different joint replacement designs. The shortcomings include inadequate study design and the lack of comparative data. Despite repeated calls for standardisation of outcome measures, this has yet to be achieved. Considerable resources are often invested in outcomes monitoring programs.It is therefore important that instruments are selected based on them meeting strict psychometric criteria, that adequate follow-up is achieved and that appropriate data analysis techniques are utilised, otherwise interpretation of results is difficult. We have found that patients’ reporting of symptoms and outcomes after hip arthroplasty were found to be consistent with those reported by their reviewing doctor. We therefore suggest that for uncomplicated joint arthroplasty cases, the marginal costs of their regular review in outpatients probably outweighs the marginal benefits and important resources and doctors time would be made available for other patient care activity if these patients were reviewed by patient self-administered questionnaires. Our studies have shown that SF-36 health survey and the WOMAC instruments are useful when administered by mailed survey, however, the cost-benefits of using these outcomes instruments is an important consideration. The lack of comparable outcomes data should encourage greater orthopaedic participation in multi-centre outcomes studies including randomised trials.

Reported rates of dislocation after primary and revision total hip replacement (THR) vary widely, whereas subluxation after THR is not commonly reported. Importantly, it is now recognised that reported dislocation rates are likely to be an underestimate of the true dislocation rate. The primary aim of this study was to develop and validate a Patient Hip Instability Questionnaire and subsequently to use this questionnaire to determine the incidence of dislocation, subluxation and symptoms due to hip instability following primary and revision THR. In addition the associated costs, morbidity, disability and effects on health-related quality of life were examined.

A retrospective review of dislocation rates from 1996 to 1998 identified problems in determining the true dislocation rate from standard hospital and database records. Therefore, a patient-completed Hip Instability Questionnaire was developed and validated to monitor dislocation and subluxation rates. This was then mailed to patients three and 12 months following primary or revision THR. All dislocations were then confirmed by telephone interview and radiographs. Telephone interviews and patient completion of the SF-36 questionnaire were used to assess morbidity, disability and quality of life. Costs of treating patients with hip dislocation were also determined.

The response rate to the mailed questionnaire was greater than 95%. The questionnaire was shown to be a valid measure of the true rate of dislocation following THR and confirmed the inaccuracies in previous methods of determining dislocation rate based on hospital and database records. Using this questionnaire, the rate of subluxation was higher than previously reported and the significant morbidity and health care costs associated with with this complication were identified.

The use of this questionnaire will allow better assessment of morbidity and costs due to complications following THR.

Introduction: Type C pelvic ring disruptions are commonly associated with significant patient morbidity. It is the senior author’s (APP) experience that the sacro-iliac alar cartilage is commonly damaged at the time of initial trauma. If left untreated, this may give rise to post-traumatic arthrosis of the joint, with resultant pain. The natural history of type C disruptions is one of late pain. In this paper, we review our results of acute arthrodesis of the SI joint simultaneously with fixation of the posterior pelvis.

Methods: From 1987–2000, a consecutive series of 28 patients who underwent primary surgical fusion and internal fixation of the sacro-iliac joint underwent clinical and radiographic review. All patients were examined at latest follow-up (79.8 months) in regards to pain, range of motion, walking tolerance and the incidence of significant complications. Evaluation of the pelvic ring reduction and success of arthrodesis of the SI joint were made through radiographs of the pelvic ring. In addition patients completed the SF-36 as a measure of general health status and the Musculoskeletal Function Assessment (MFA) and WOMAC scores as a measure of functional outcome. Work status was also examined.

Results: The majority of these injuries were sustained in either motor vehicle crashes or high energy falls. There was a high incidence of associated injuries and co-morbidities. The male to female ratio was approximately 2:1 with a mean age of 27 years. At initial surgery, all patients were noted to have severe fragmentation and disruption of the alar cartilage. The majority of patients had sacro-iliac screw fixation for their posterior injury and an external fixator for anterior stabilization. At follow-up there was a low incidence of late posterior complex pain. All patients were independently mobile and there were minimal complications. Only 1 patient had to change jobs secondary to pelvic or low back pain. The functional outcome at long term follow-up was good with regards to the SF-36, MFA and WOMAC scores.

Conclusions: Type C pelvic ring injuries have a high incidence of disruption of the alar cartilage. Treatment of these injuries by primary fusion and internal fixation leads to good long-term results.