The aim was to review patients that had single stage bilateral total hip joint replacements (SSBTHJR) of two surgeons in the Wellington area, to assess symptomatic relief and overall quality of life before and after surgery. To also review xrays of this population to assess acetabular component orientation.

Fifty patients from two hospitals, with minimum follow up of two years, who had SSBTHJR, were reviewed for duration of stay, time to mobilisation, and complications (eg. wound infections, venous thrombus and embolism (VTE), gastrointestinal ileus, and cardiac events). Patient opinions on hip joint function (Oxford Hip Score) and overall quality of life (EQ-5D Score) were performed (37/50 patients could participate). Patient’s postoperative radiographs were analysed with Polyware Auto Version 6.00 to measure acetabular cup orientation for both sides.

Oxford Hip Score mean was 20.5 (range 12 – 56), compared to the national mean 19.3. The median score was 14. Most patients (65%) had no symptoms of pain, difficulty in mobilising, or performing activities of daily living (ADL). 19% of patients had mild to moderate symptoms/difficulty, and 16% had significant pain/difficulty On average, using a visual analogue scale, patients felt their health was 42% better after having their surgery. Complication rates were minimal, and were primarily superficial wound infections. Hip acetabular cup positioning analysis was performed (statistical analysis pending).

Patients undergoing SSBTHJR have comparable results for Oxford Hip Scores compared to unilateral THJR patients, improved lifestyle, but not increased complications.

The aim was to evaluate the polyethylene wear in an uncemented all polyethylene titanium coated acetabular cup a minimium of ten years post-operatively, and to determine the effect of supine “stress” radiographs on 3-dimensional polyethylene wear, compared with “non-stress” radiographs.

Twenty seven hips in twenty five patients were examined, and standard and stress radiographs were performed. All radiographs were analysed using Polywear 5 auto, to measure 2d, 3d, and volumetric wear. Wear measurements were performed three times to minimise error. Radiographs were analysed for osteolysis.

There were 12 males and 13 females. Eighteen patients had a diagnosis of osteoarthritis.20 patients had a ceramic head and 7 a metal head. There was no association between wear rates and age, weight, diagnosis, Harris hip score or femoral head type. There was no acetabular osteolysis. The average linear wear was 0.11 +/− 0.08 mm/yr. The stress radiographs did not influence the 2D or 3D wear measurements.

This sudy shows a similar wear rate to most published series. The stress radiographs did not influence the wear measurements. The absence of osteolysis is of interest as other uncemented cups have significant osteolysis at ten years.

In the past measurement of deformity correction in spinal surgery has been done using measurements made directly from radiographs using a pencil, ruler and goniometer The aim of this paper is to describe a reproducible, accurate and partially automated system that has been developed for measuring x-rays of patients with spinal disorders.

Computer assisted measurement of polyethylene wear in patients with THJR is now well established. Many of the image processing algorithms have been modified to allow identification of the outline of both thoracic and lumbar vertebral bodies on digital images of radiographs made from patients with spinal disorders. The Genetic Algorithm (GA), a branch of Artificial Intelligence, has been adapted to allow the modelling of a four sided figure to each vertebral body, with minimal user input.

The accurate identification of each vertebral body within a spinal radiograph allows measurement of multiple parameters, including Cobb angles, vertebral width, vertebral height and cross sectional area, as well as measurement of average disc height and cross sectional area. The method is 100% reproducible for each digital image. An attempt to measure accuracy has not been made because these are two dimensional measurements of a three-dimensional structure.

Comparison of these measurements between pre and post-operative radiographs for a patient allows accurate and reproducible measurement of reconstructive surgery for scoliosis and other spinal disorders. It may aid in development of a classification system for scoliosis.

Introduction and Aims: Single-stage bilateral total knee arthroplasty is an uncommon and often controversial procedure. Recent reports have refined the data relative to bilateral total knee arthroplasty and complications, which include myocardial infarction, deep vein thrombosis, pulmonary embolus and death.

Method: A retrospective study of the cases of total knee arthroplasty performed by the senior authors in the last 10 years examines details of surgery and anaesthesia, pre- and post-operative management to identify the occurrence of complications. Patients also completed an Oxford Knee Score and a questionnaire relating to their experience of having a bilateral procedure.

Results: While the outcomes and cost benefits of single-stage bilateral replacement are established, the risk of complications remains. This study establishes the low complication rate associated with this procedure in the senior author’s hands and documents the high patient satisfaction from it.

Conclusion: The study demonstrates that, in selected patients, simultaneous bilateral knee replacement surgery can be performed with good outcomes without a definite increase in peri-operative risk.

Introduction and Aims: The aim of this study is to identify specific risk factors for developing haemophilia-related orthopaedic complications and to provide a qualitative and quantitative analysis of the orthopaedic management of haemophilia complications.

Method: A postal survey was sent to 48 patients on the Wellington region haemophilia database. The questionnaire covered both qualitative and quantitative questions covering the participants’ current condition and treatment, past and present orthopaedic and non-orthopaedic management, support, education, employment and leisure activities.

Results: Twenty-five patients returned the questionnaire, a response rate of 52%. Most of the participants (68%; 17/25) felt that their education had been compromised as a result of haemophilia complications. Of those participants that were 16 years or older, 68.4% (13/19) felt that their working opportunities had been compromised as a result of haemophilia complications. Despite patients less than 18 years of age receiving prophylactic Factor VIII replacement (n=7) and all patients having Factor VIII available on demand, 18 patients had significant bleeds in the previous six months. Most bleeds were into joints, 13 knees, 13 ankles, 12 elbows, six shoulders and three hips, but a significant number of intra-muscular bleeds (n=22) also occurred. There were 62 painful joints reported by 19 patients, the ankle being most common (n=21), followed by hip (n=13), elbow (n=12), and knee (n=8). Twenty-five orthopaedic operations were described by eight patients, mainly knee (n=11) and hip (n=5) replacements, and synovectomies (n=9). In the last year, two patients who have factor VIII inhibitor had been successfully operated on, one for a large pseudotumor of the thigh, and the other for contralateral hip and knee joint replacement.

Conclusion: Despite good medical management, recurrent joint bleeds are a major problem in haemophilia. Many study patients commented that orthopaedic procedures were not performed readily enough, and that by the time they received their operation, their function had deteriorated significantly.

Introduction and Aims: Polyethylene wear after total hip arthroplasty with an uncemented titanium coated non-modular acetabular component was measured using a computer-assisted technique and correlated with clinical outcomes. Polyethylene wear measurements using post-operative radiographs and recent supine and standing radiographs were compared to see if there was a difference. To date, there is no definitive evidence in the literature that indicates a difference.

Method: Fifty-five patients who had total hip arthroplasties using a non-modular titanium-backed Mathys (Protec, Switzerland) press-fit acetabular component in 1992–1993 were included in this study. Patients who had a revision were excluded. The patients were contacted and reviewed in clinic. Each patient completed an Oxford Hip Score. They also had a cross-table lateral, supine and standing AP radiographs. The radiographs were digitised and analysed using a computer-assisted method (PolyWare) of measuring polyethylene wear. Correlations were sought between the rate of polyethylene wear and clinical outcome using the Oxford Hip Score. Polyethylene wear measurements using supine and standing radiographs were also compared to determine if there was a significant difference.

Results: Early results showed a trend indicating a difference in measured polyethylene wear rates comparing supine and standing radiographs. Previous experience at this institution measuring polyethylene wear using the same computer-assisted technique has shown that leg position has an effect on polyethylene wear measurements; weightbearing radiographs with the leg maximally internally and externally rotated resulted in an increase in polyethylene wear calculation of volumetric wear by 35% as compared to calculations with supine radiographs. A non-cylindrical wear tract was proposed to be the reason for the difference. There is no definitive answer in the literature as to the significance of the effect of supine versus standing radiographs on the measurement of polyethylene wear. Polyethylene wear rate did not seem to be related to clinical outcome as detected by the Oxford hip score.

Conclusion: Early results indicate a difference in polyethylene wear measurement comparing standing and supine radiographs. Polyethylene wear rates using the Mathys acetabular component do not seem to be related to clinical symptoms as detected by the Oxford Hip Score.

Introduction and Aims: In 1999, the serial polyethylene wear of a group of patients with a porous coated anatomic hip (PCA) replacement were reported by Devane et al. Wear was measured using a computer assisted technique where the points were selected manually from a digitised image displayed on a computer screen (method 1). The purpose of this study is to use a new automated method of polyethylene wear measurement (method 2), for analysis of the same serial radiographs of patients which have since been digitised. Results of the two methods are compared.

Method: Twenty-three porous coated anatomic hips (PCA, Howmedica) in 23 patients had serial radiographs performed with a minimum 8.5-year follow-up. A total of 494 anteroposterior (AP) and lateral radiographs were analysed. Assessment of the presence of osteolysis on the longest-term follow-up AP image was made by an independent observer. Correlation of polyethylene wear rate measured by the two different methods, and osteolysis was made.

Results: Using method 1, if a poor quality AP or lateral image was analysed multiple times by the same observer, a poor reproducibility (±0.4 mm) was obtained. Discarding of poor quality radiographs by the user resulted in 74% of the AP images and 68% of the lateral images being measured. It is very likely that a different user would discard different images. Method 2, however, automatically eliminates poor quality images. Method 2 was able to measure 89% of the AP radiographs and 78% of the lateral radiographs. More importantly, if a different user performed the same analysis using the new automated software, the exact same images would be analysed. Results of wear measurements made using method 1 were statistically similar to measurements made using method 2 in 19/24 hips (83%).

7/23 patients demonstrated osteolysis on their images. Wear measurement using method 2 showed statistically greater wear in these patients (69mm/yr vs 35mm/yr, p = 0.003). Wear measurement using method 1 showed only a weak association.

Perhaps most importantly, wear analysis of these patients using method 2, by two separate observers, independent of each other, gave identical results.

Conclusion: With improved accuracy and elimination of user error, measurement of PE wear may now have the ability to make predictions about the long-term survival of a THJR. Clinical decisions may be able to be made based on individual patient measurements.

Our aim was to assess the impact of the increasing number of patients on orthopaedic waiting lists on general practitioners in New Zealand.

A 10-point questionnaire was developed in association with the General Practice Department at the Wellington School of Medicine, and mailed to 250 randomly chosen general practitioners around New Zealand. One hundred and fifty general practitioners returned the survey.

Sixty three per cent of general practitioners reported having between eleven and thirty patients on an orthopaedic waiting list in their practice. 85% of general practitioners reported spending up to an extra 6 hours per month looking after problems caused by having to provide extra care for the patients. In 90% of cases general practitioners reported that their patients required considerably greater community support in the form of extra physiotherapy, meals-on-wheels and occupational therapy. In 138 cases, general practitioners reported greater levels of stress in the families of patients on waiting lists. The majority of general practitioners reported an increased need for analgesia and night sedation during the period on a waiting list. They also reported substantial increases in paperwork necessary to access social supports.

This study documents the burden on general practitioners produced by the increasing waiting lists, and the re-alignment of waiting lists. This burden is reducing the general practitioner’s ability to deal with routine general practice problems, and likely adversely affects the health of other New Zealanders. There is a need for a study of patients on waiting lists to further assess their needs.

Single-stage bilateral total knee arthroplasty is an uncommon and often controversial procedure. Recent reports have refined the data relative to bilateral total knee arthroplasty and complications which include myocardial infarction, deep vein thrombosis, pulmonary embolus and death. Less significant complications, including post-operative ileus and pseudo-obstruction are also more common following bilateral replacement.

A retrospective study of the cases of total knee arthroplasty performed by the senior authors in the last ten years, examines details of surgery and anaesthesia, pre and post-operative management to identify the occurrence of complications. Patients also completed an Oxford Knee Score and a questionnaire relating to their experience of having a bilateral procedure.

While the outcomes and cost benefits of single stage bilateral replacement are established, the risk of complications remains. This study establishes the low complication rate associated with this procedure in the senior authors’ hands, and documents the high patient satisfaction from it.

The study demonstrates that, in selected patients, simultaneous bilateral knee replacement surgery can be performed with good outcomes without a definite increase in perioperative risk.

We assessed the functional and health outcomes of patients treated for a hip fracture ,6–12 months following the injury.

One hundred and ninety six patients over 60 years of age ,admitted with a subcapital or intertrochanteric fracture were sent two questionnaires, an EQ-5D, and a Hip specific outcome questionnaire based on the WOMAC .Patients with pre-existing dementia were excluded.108 (55%) returned completed questionnaires.

There were 36 males and 72 females with an average age of 81. The average time since fracture was 8.44 months. There were 46 intertrochanteric and 62 sub-capital fractures.WOMAC scores averaged 35 for intertrochanteric fractures and 25 for subcapital fractures. Males scored higher than females (31 v’s 24)Age had no influence on WOMAC scores.EQ 5D results were compared with the general population, and showed significant problems with mobility, pain, performance of usual activities, and self care.

This study shows that despite seemingly successful treatment of the fracture, patients suffer very significant reductions in function and quality of life. Greater effort needs to be made to address these issues rather than concentrating on the development of new fixation devices, if we are to improve the results of treatment of these increasingly common fractures.

The purpose of this study was to document difficulties encountered by orthopaedic surgeons with the removal of titanium implants.

A postal questionnaire was sent to all members of the New Zealand Orthopaedic Association seeking to document difficulties with the removal of titanium implants: screws, plates or intramedullary nails. The questionnaire included length of device implantation, estimated increase in theatre operating time over the expected time for the procedure, and complications encountered during the device removal.

Twenty six surgeons responded to the study. Six reported no difficulties in removing implants, 18 reported significant difficulties, and 2 had not had to remove titanium implants. Of the 18 surgeons reporting difficulties, 10 had problems with intramedullary nails, 4 with plates, 6 with screws and 1 with another device. The estimated increase in operating time varied between 20 and 140 minutes. Major complications reported included breaking intramedullary nails, screw heads shearing off, and damage to the underlying bone.

This survey demonstrates significant problems in removing titanium implants. Surgeons need to be aware that when using these devices difficulties with their removal can be encountered and patients should be warned that further injury may be sustained during device removal.

Forty six periprosthetic femoral fractures adjacent to a hip prosthesis have been retrospectively reviewed. Follow up included chart and radiograph review, Oxford Hip Score and SF-12 Global Function Score. Fractures were treated with internal fixation or revision arthroplasty without the use of allograft.

All the fractures united and functional outcome was good. The mean Oxford Hip Score was 26 and the SF-12 was 33. Complications were related to the severity of the fracture according to the Vancouver classification.

These results and a review of the literature support the ongoing management of periprosthetic femoral fractures without allograft.

The aim of this study was to document the medium-term results of the use of fluted, tapered, titanium femoral stem in revision total hip arthroplasty.

Seventy patients undergoing total hip revision using a tapered, grid-blasted titanium modular femoral stem were reviewed at a mean follow-up time of 47 months. Femoral defects were classified according to the Pak and Paprosky system, and femoral bone quality was assessed with the Bohm and Bischel system. Clinical function was measured by the Oxford Hip Score. Radiograpic analysis was performed in all cases.

Stems were classified as a failure or re-revision in 4.3% of the cases. Three required reoperation for recurrent dislocation, in each case the femoral component alone had been revised during the most recent revision. The postoperative mean Oxford Hip Score was 20.9. Subsidence of the component was noted in 84% of hips but did not cause a significant problem. Final leg length discrepancy was 5.4mm.

The results of this titanium, tapered, grid-blasted modular stem compares favourably with other revision stems including the Oxford Hip Score compared to the results for revisions recorded in the National Joint Register (Oxford Score 24.3). Although technically demanding this stem offers a very satisfactory solution for revision of total hips in almost all circumstances.

We assessed the functional outcome of fractures of the os calcis a minimum of twenty- four months following injury.

Eighty-three patients with 85 fractures were assessed a minimum of two years following fracture of the os calcis, using a validated functional outcome measure designed specifically for fractures of the os calcis, and an EQ5D. Radiographic analysis of all fractures was performed to attempt to correlate outcome scores with the fracture pattern.

Sixty per cent of the questionnaires were returned completed. Forty percent of the fractures were treated surgically, the remainder with a period of weight relief, followed by physiotherapy and graded weight-bearing. The majority of patients reported a mild hind foot pain (8/10 on a VAS), and all reported some difficulties with walking on uneven terrain. There was no appreciable difference in the outcomes comparing patients treated by open reduction and internal fixation and those treated non-operatively.

This study demonstrates a surprisingly high patient satisfaction rate following fractures of the os calcis whether they are treated operatively or non-operatively. Patients seemed to have compensated for any altered function very well. We were not able to identify specific fracture patterns that were associated with poorer outcomes.

The purpose of this study was to assess the regional variation in the incidence of hip fractures in patients over 65 years. in New Zealand. Data from the National Minimum Data Set (NMDS) for hip fractures from 1 July 1998 to 31 June 2000 was obtained. The data was divided into 21 District Health Board (DHB) regions by mapping from domicile code to DHB. Population of interest as at 30 June 1999 was estimated on the basis of previous census in 1996. The incidence of hip fracture per 100,000 for each region was calculated and divided into age and sex cohorts.

There is a significant difference between DHBs in the sex and age adjusted incidence of hip fractures. The rates ranged from 556 per 100,000 to 838 per 100,00. As expected there was a higher fracture rate in women and the fracture rate increased with age. There was a weak correlation with sunshine hours (p=0.029) with increasing fracture incidence as sunshine hours decrease.

This study demonstrates a large variation in the incidence of hip fractures per DHB region. The cause for this is unclear, but the cost implications are significant. DHB’s with a high incidence of hip fractures in their region may wish to investigate strategies for reducing the incidence.

Aim: To examine the effect that a modular, uncemented, fully coated titanium stem (PFM-R, Protek) has on the bone stock of revised femora.

Methods: Forty revision hip arthroplasties between 1997–2000 were performed by one surgeon using the PFM-R revision stem. The patients were assessed radiographically over a two-year follow-up period. The pre-operative radiographs were examined for bone defects according to Paprosky et al., 1987. Serial radiographs taken post-operatively after two days, six weeks, three months, six months, 12 months and 24 months were used to assess signs of fixation, stability and change in the cortices of 16 femoral zones according to criteria set out by Engh et al., 1987. The change in the density of the bone defects identified at the time of surgery was also examined.

Results: The average age of the patients was 65 years. Thirteen revision stems were followed for one year and 13 were followed for two years. Fourteen patients had an incomplete radiographic follow-up. Two type I defects, 23 type II defects and one type III defect were identified. Twenty-one of the 23 type II defects showed evidence of regeneration in the subtrochanteric metaphysis. One revision stem had radiographic evidence of bone resorption proximally though three stems subsided. No stress shielding was seen distally.

Conclusion: At early follow-up the PFM-R appears to be a viable revision femoral implant which facilitates the regeneration of metaphyseal bone stock.

Purpose: To examine the histology of the bone cement interface in a canine total hip model comparing two different cementing techniques.

Methods: Seven adult mongrel dogs underwent staged bilateral total hip replacement, on one side cement was finger packed into the femur, on the opposite side the femoral canal was washed, brushed, distally plugged and pressure injected with cement prior to inserting the femoral component. Sequential flurochrome bone labelling was performed. The dogs were sacrificed up to six months post surgery. Under-calcified sections of the femur were examined by fluorescent microscopy.

Results: Post-operative radiographs showed complete filling of the proximal femur with cement in the pressure injected group, and a relatively thin mantle in the finger packed group. Histology of the finger packed group showed minimal intrusion of cement into the cancellous bed, direct opposition of cement and bone with small areas of fibrous tissue interposition. In the pressure injected group the cement extended to the endosteal cortex, there was no bone necrosis, and the intruded bone underwent remodelling similar to that at the margins.

Conclusions: This study suggests that “third generation” cementing techniques result in greater contact between bone and cement, and may explain the claim that femoral stems in humans inserted using third generation techniques are more durable than those inserted using “first generation” techniques.

Introduction: Ankle fractures are the third most common fracture presenting at public hospitals in New Zealand. There have been few outcome studies following treatment of ankle fractures.

Aim: To identify the relationship between three types of ankle fractures and the functional and quality of life outcomes for patients two years after the injuries.

Methods: Seventy-four patients seen at Wellington Hospital with ankle fractures during 1998 were contacted for the study. Patients had been treated by open reduction and internal fixation, or by the application of a plaster cast with manipulation of the fracture being performed where necessary. Each patient completed an ankle specific Olerud and Molander questionnaire and an EQ5D Quality of Life Outcome measure. All x-rays were analysed and the fractures were classified using the Weber classification.

Results: There were 22 males and 52 females, 11% had Weber type A fractures, 67% had Weber type B, 18% Weber type C and 4% an isolated posterior malleolar fracture. Fifty-one patients underwent surgery. Patients who sustained Weber type A fractures generally recorded good to excellent OMA scores, while those with Weber Band C fractures produced significantly poor results. An analysis of the ankle visual analogue score versus the method of treatment showed that patients who underwent surgery judged their ankle to be less functional than the patients who had non-surgical interventions. The mechanism of injury also correlated with the end result, patients who had injured their ankles during sporting activities scored lower scores than those who had injured their ankles in simple falls. Patients requiring removal of an internal fixation device had a lower OMA score when compared with those who retained their fixation devices in situ.

Conclusions: This long-term out come study indicated that there was significant dysfunction following ankle fractures, with a surprising level of disability following Weber B and C fractures. The results of this study do not indicate better results in those patients who underwent surgery.

Purpose: To measure quality and quantity of sleep in patients before and after hip arthroplasty.

Methods: A prospective survey where 50 participants were sent a sleep diary, an acti-watch motion-logger, and a 32 item sleep questionnaire. These data were collected at least four weeks prior to and three months after surgery. Data analyses included descriptive statistics and within-subject pre and post surgery comparisons. For the subjective data, comparison was by the McNamar Test for the significance of changes. For the acti-graphy variables, comparison was by mixed model analysis of variance.

Results: Preliminary results indicate that subjective measures of sleep quality improve significantly three months after hip arthroplasty, e.g. patients rated their sleep disturbance due to hip-pain on a scale from 1=never to 4=always. 75% of patients reported an improvement, and 25% reported no change in this variable, post surgery. Acti-graphy measures confirm the overall improvement in sleep quality (for sleep efficiency, (p(f)=0.05) and fragmentation index, (p(f)=0.05), and a reduction in mean activity during sleep (p(f)=0.04). Ongoing analyses are addressing the reliability of subjective measures compared to acti-graphy and why some patients show greater improvement in sleep than others, after hip arthroplasty.

Conclusions: Findings suggest that sleep disturbance occurs as a result of painful osteoarthritis in the hip, and that this can be significantly ameliorated by hip arthroplasty surgery. The expected improvement in quality of life and level of day to day functioning that accompany improved sleep are perhaps an under-rated benefit of this procedure.

Introduction: Long waits for total hip joint replacement (THJR) surgery affect quality of life and are likely to impose significant medical, personal and other costs on individuals and society.

Aim: To define the economic and health costs of waiting for THJR surgery.

Method: A prospective study of 130 patients requiring primary THJR is being undertaken. Data on health related quality of life (HRQL), using self completed EQ-5D and WOMAC questionnaires, are collected on enrolment, and every month before surgery and continuing for six months after surgery. Monthly cost diaries are used to record medical, personal and other costs. Inferential statistics and regression analyses will be used to test the strength of associations between costs and waiting times, and changes in HRQL before and after surgery.

Results: Preliminary results indicate that costs are greatest before surgery (mean=$70.41 per person, per month), remain high during the first month after surgery (mean=$53.24 pp pm), and drop significantly (p< 0.05) within six months after surgery (mean=$12 pp pm). WOMAC scores of pain, stiffness and physical function show significant improvements (p< 0.05) within three months after surgery. The EQ-5D also indicated significant (p< 0.05) positive changes.

Conclusions: The preliminary results suggested that patients had high dependency levels for the first month after surgery. Consequently, costs associated with recuperation after surgery may have shifted from the public hospitals onto the community and family. Significant improvements in HRQL by three months after surgery indicated that THJR is a successful intervention for osteoarthritis.