Single stage bilateral total knee replacement is an uncommon and often controversial procedure. Some authors have reported significant complications. We have reviewed our experience with the procedure in 40 cases.

Forty patients undergoing simultaneous bilateral total knee replacement with a minimum follow up of two years were reviewed. Thirty of the patients completed an Oxford Knee score and an EQ-5D. Eight patients were lost to follow up. Two were deceased.

The age at the time of surgery ranged from 25–87 years – mean 68yrs. 8o% were done under general anaesthetic. 50% required blood transfusion in the post operative period, the average volume being 4 units. 50% had physiotherapy following discharge. There were 4 patients with delay in wound healing and 1 patient who had an infection requiring wound debridement. There were no other significant complications. The mean Oxford Knee score was 21.6, the mean score for primary unilateral knee arthroplasty for patients on the National Joint Register is 23.5. The EQ-5D scores were very satisfactory.

This study demonstrates that in our unit this procedure can be performed with minimum complications and the expectation of an excellent outcome.

We analysed factors affecting the rate of recovery from ankle fractures. Delays in return to normal functioning may relate to poorer quality and duration of sleep during recovery.

This prospective study investigates the relationship between the rate of recovery from ankle fracture and sleep disturbance, comparing ankle fractures classified using AO-Danis-Weber Classification – types A, B & C treated at Wellington Hospital, aged between 18 and 55 years. From June 2003 to October 2004 participants completed an ankle fracture questionnaire, and a general health profile at three, six and twelve months post-injury. A randomly selected subgroup was interviewed to identify specific recovery issues.

Six percent were Weber A, 56% B and 39%, C. Mean (and standard deviation) for return to normal functioning was; 5 (2); 8 (3) and 8 (7) weeks respectively, overall range – 2 to 24 weeks. Those who returned in 2 weeks had sedentary jobs, worked from home or were students, all with a high level of support by ACC. Physically demanding occupations delayed return to work. After one year, (93%) scored 85 – 90% satisfaction with their ankle performance. 97% scored highly on the SF 36, indicating positive life attitudes. 98% reported no change from their pre-fracture sleep patterns.

Rate of recovery is less predictable and sometimes more prolonged for Weber C than for A and B ankle fractures. Earlier return to work is a function of practical support in the workplace and positive health attitudes including balanced sleep patterns. Work planning and workplace assessment are significant factors.

This study examined the effect of completely disregarding dislocation precautions on the incidence of dislocation, as well as the speed of patient rehabilitation after THJR

Since 1^st March 2005, all uncomplicated primary THJR’s performed by one of the senior authors for OA have been told by their physiotherapist to do what they like, when they like, during the post-operative period. All patients were operated on through a modified direct lateral approach A representative sample of 30 patients were administered a questionnaire at their 6 week postoperative visit.

There were no dislocations. Of those patients in full-time employment, the majority had returned to work by 6 weeks. Most were able to drive between 3 and 4 weeks. Nearly all had regained their pre-operative range of movement and could put on their own shoes and socks. All claimed that being told to disregard dislocation precautions gave them more confidence in their THJR and helped with their achieving a speedy recovery from surgery.

Patients who are judged at the time of surgery to have a stable THJR articulation, benefit form being told to disregard the usual dislocation precautions, and are able to return to work and driving in a more timely manner.

The aim was to investigate whether or not the pre-operative injection of cortico-steroids into the knee influences the infection rate of a subsequent total knee replacement.

This was a case controlled study, in which it was calculated that 152 controls and 38 infected cases would give sufficient power to the study. The infection group had to have had a delay in wound healing or have had a revision for infection.

A total of 32.8% had had an injection at some time pre-operatively. The average number of injections was 2.23, with a range of 1–15. 37% were performed by a G.P., 35% by an orthopaedic surgeon, and 22% by a rheumatologist.79% had the injection within 12 months of surgery. The rate of injection was the same in the two groups. There was no significant difference in the infection rate between the two groups (OR 1.38; 95%CI 0.55–3.31)

Despite recent literature indicating that there is a 10% increase in infection in patients having steroid injections into the hip prior to THR this study does not confirm this risk in patients undergoing TKR.

The aim was to determine how periprosthetic hip and knee infection and subsequent revision impact on patient lifestyle and function. While the literature abounds with studies of outcomes of revision surgery for prosthetic infection, few studies address functional outcome and patient-based outcome measures.

This retrospective study examined a consecutive series of revision total knee and hip arthroplasties performed for infection between 1996 and 2002 by surgeons at Wellington Hospital. Eight knees and ten hips were treated with a two-stage exchange using antibiotic spacer and IV antibiotics. Two knee and seven hip patients underwent direct exchange procedures.

In 90% of knees and 65% of hips Infection was successfully eradicated after one revision. One (10%) knee and eight (47%) hips required further intervention of either surgery or antibiotic therapy. Mean Oxford Scores for knees and hips were 29.6 and 29.5 respectively. Oxford scores following revision for infection were slightly higher compared with scores following the primary procedure, indicating poorer functional outcome. EuroQol-5D responses indicated a lower level of function than that of a general population sample, with problems in the areas of mobility, usual activities, and pain/discomfort, most apparent.

While functional outcome is intrinsically related to both the amount of destruction caused by infection and the eradication of infection, absence of re-revision in itself cannot be equated with functional success. Although TKA/THA revision is a technically challenging orthopaedic procedure, patients do attain favourable results. Surgical revision of a prosthetic joint implant for infection can be associated with reasonable function and satisfaction scores.

To review the results of revision THR performed with a modular titanium tapered uncemented stem in two cohorts of patients to assess whether subsidence of this type of stem is avoidable through improved surgical technique.

The first 70 patients undergoing revision THR with this type of stem were compared with 38 patients who had their revision in the last 24 months and had a minium follow up of 12 months., with particular reference to stem subsidence. All patients were also assessed with the Oxford Hip Score. All radiographs were reviewed to measure subsidence. Identical post-operative management was used in both groups.

The mean subsidence in the first group was 11.7 mm and in the most recent group 4mm. The Oxford Hip Score in both groups was similar (20.9) which compares very favourably with the OHS score from the National joint Register for revision arthroplasty (24.3).

This comparison shows that changes in surgical technique can limit the subsidence seen with tapered stems used in revision total hip replacement. No bone grafts were used in either series, only small changes in bone preparation, and prosthesis selection were used .The outcome as determined by the OHS was similar in both groups.

To assess if highly cross-linked polyethylene is associated with less linear wear than ultra high molecular weight polyethylene in vivo.

To assess whether alteration in biomechanical characteristics of the reconstructed hip influence’s wear patterns.

A randomised prospective trial comparing conventional polyethylene with highly cross-linked polyethylene in an acetabular component was designed. Identical cemented stems were used in all cases, with a metal head. The polyethylene thickness was controlled. The trial design required 124 cases to be entered to give the study sufficient power to determine any difference in wear rates. Polyware Auto was used to assess 2D wear rate and volume.

This paper presents the preliminary results of the early patients entered into the study and looks at both 2D wear or creep at 18 months post operatively, and seeks to establish any relationships between 2D movement and biomechanical characteristics of the reconstructed hip.

There was no significant difference in the 2D wear (or creep) between the two types of polyethylene at 18 months. There was no correlation between femoral offset, cup offset, or centre of rotation offset and 2D wear (or creep).

This preliminary data shows no difference in the early wear rate of the two types of polyethylene. This is in contrast to an in vitro wear simulator study that has shown more creep in highly cross-linked polyethylene. The significance of this observation is unclear. We hope to demonstrate that as the trial progresses any difference in the performance of the two types of polyethylene should be evident.

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

Method: A prospective cohort of 122 patients requiring primary total hip arthroplasty (HA) was recruited from four hospitals. Health-related quality of life (HRQL) using self-completed WOMAC questionnaires was assessed monthly from enrolment pre-operatively to six months post-surgery. Monthly cost diaries were used to record medical, personal and other costs. Data was analysed using PC-SAS to test the strength of associations between costs and waiting times, and changes in HRQL pre- and post-surgery.

Results: The mean waiting time was 5.2 months, and the mean cost of waiting for surgery was NZ$1376 per person per month, with medical, personal, and social costs contributing NZ$404, NZ$399, NZ$573, respectively. Waiting for more than six months was associated with an increased cost of NZ$730 per patient per month for a total cost of NZ$2177 per patient per month. Age was correlated with greater loss of income and higher medical costs. An incremental improvement over time in WOMAC scores post-operatively was identified. Older age, community services card use and a greater number of months waiting were negatively correlated with post-surgical improvement.

Conclusion: Longer waits for HA incur greater economic costs and impact on patient recovery. This shows that shorter waiting time for HA significantly reduces costs to individuals and society and improves health outcomes.

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.

We have developed and tested the accuracy of a completely automated method for polyethylene (PE) wear measurement of digitised antero-posterior and lateral radiographs.

New computer algorithms have been developed to measure PE wear on digitised hip radiographs. The only user input required is the file name of the x-ray. Validation was performed by simulation of PE wear in an acrylic phantom. Radiographs were analysed with the new software and results were compared to know penetration of the femoral head.

Accuracy using 10 antero posterior and lateral phantom radiographs was within ±0.08mm (95% CI) of the real femoral head penetration. There was no inter or intra-observer error (identical results with all measurements). Perhaps most importantly, this system gave accurate results in 94% of 600 clinical radiographs of variable quality. Only 74% of this same group of radiographs were considered of sufficient quality to allow reliable manual measurement.

This new method of PE wear measurements eliminated inter and intra-observer error, allowing comparison of wear results between different institutions. Accuracy is improved, but still limited by resolution of the scanned image.

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.

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.