The purpose was to define the economic and health costs of waiting for total hip joint replacement surgery. A prospective cohort of 122 patients requiring primary hip arthroplasty (HA) was recruited from four hospitals in the lower North Island. 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.

The mean waiting time was 5.2 months and mean cost of waiting for surgery was $1,376 per person per month (pp pm) with medical, personal and social costs contributing $404, $399, and $573, respectively. Waiting more than 6 months was associated with an increased cost of $730 pp pm for a total cost of $2177 pp pm (p< 0.003). Age was correlated with greater loss of income (< 65 years) (p=0.001) and higher medical costs (< 65 years) (p=0.08). An incremental improvement over time in WOMAC scores post-operatively was identified (p=0.0001). Older age (p=0.01), community services card use (p=0.003) and a greater number of months waiting (p=0.1) were negatively correlated with post-surgical improvement after adjusting for other variables. Longer waits for HA incur greater economic costs and impact on patient recovery. This lends weight to the view that a shorter waiting time for HA significantly reduces costs to individuals and society and improves health outcomes.

The purpose of the study was to assess the incorporation of defatted, and deproteinated bovine cancellous bone in a sheep bone graft model. Cylindrical defects were created in the femoral condyles of 12 sheep using custom-made trephines. The defect was filled with a cylinder of prepared bovine bone. The removed cylinder of bone was implanted into a defect created in the opposite femoral condlyle. Fluorochrome bone labels were administered over an 8-week period and the sheep sacrificed at 10 weeks. Undecalcified thin bone sections were viewed with a fluorescent microscope.

ln one sheep there was a technical problem leading to unsatisfactory histology. All other sheep showed similar histology. The autograft incorporated rapidly with the graft showing a rim of reactive bone and the graft itself showing rapid laying down of new bone on its surface. The xenograft showed a similar reactive rim of new bone with deposition of new bone throughout the graft and resorption of the graft material.

This study demonstrates that specially prepared bovine cancellous bone can act as a scaffold for the depostion of new bone in a sheep model. The role of this material in humans is to be evaluated.

The aim of the study was to investigate functional outcomes and perceptions of quality of life in a series of elderly patients who have sustained tibial plateau fractures. A retrospective survey of all patients aged over 60 years who were admitted to Wellington and Hutt hospitals for treatment of a tibial plateau fracture between July 1996 and December 2000 was carried out. Patients were sent the Oxford 12 knee score and the Nottingham Health profile (NHP) by mail. Radiographs were reviewed to confirm fracture type and medical notes reviewed to ascertain treatment. Patients were divided into non-operative (plaster cast or brace; n=8) and operative treatment (open reduction and internal fixation (ORIF) or total knee replacement; n=15) groups.

Of 42 eligible patients, 23 returned completed questionnaires (rr=55%). The mean age of patients was 73.6 years with 16 (69.6%) females and 7 (30.4%) males. Mean time to follow up was 38.7 +/−14.5 months. The mean Oxford 12 knee score was 39.3. The mean NHP-part I scores were 17.6, 8.4, 3.3, 14.4, 2.9, 9.3 for energy level, pain, emotional reaction, sleep, social isolation and physical mobility respectively. 73% of the patients felt that their present state of health was not causing problems with any of the activities mentioned in the NHP-part II.

The perceptions of outcomes of tibial plateau fractures in the elderly after conservative treatment is comparable with operative treatment. The results show Oxford 12 Knee and NHP scores similar to other studies and indicate satisfactory knee function.

Early discharge from hospital has the potential to reduce direct costs, but may result in patients being discharged without adequate preparation for a return to the community. This qualitative study aimed to investigate patient expectations of and satisfaction with in-hospital discharge planning after hip arthroplasty in early and late discharge patient groups. A prospective study of 33 consecutive patients requiring hip arthroplasty were recruited from two tertiary hospitals in the lower North Island. Participants were interviewed using in-depth, semi-structured interviews on the day of discharge from hospital and again four-eight weeks later. Comparative analysis of the interviews from patients in early and late discharge groups was made.

Findings reveal good levels of satisfaction with discharge planning for patients in both early and late discharge groups, facilitated by the opportunity to attend a pre-assessment clinic. Discharge planning was viewed as a partnership between patients and key members of the multi-disciplinary team. While written information provided was timely, restricted opportunity for dialogue with health professionals limited patient knowledge and understanding of recovery. Different needs of participants indicate that discharge planning needs to be tailored and more responsive to individuals. The role of health professionals as a mentor-coach is pivotal. Further interaction from health professionals, as a follow-up to written information provided may be a way to improve the discharge process and lead to more consistent outcomes.

There is controversy regarding the best way to manage fit, independent patients with acute hip fractures. The aim of this study was to compare, nationally, the early complication rates of total hip arthroplasty (THA) in those patients with an acute fractured neck of femur (NOF) with a similar group of THA’s performed in patients with a diagnosis of osteoarthritis.

Using the National Hip Joint Register and the New Zealand Health Information Service Database, 200 patients with acute hip fractures undergoing THA were identified and compared to 1102 THA’s performed on osteoarthritis patients. The mortality, revision, dislocation and infection rates were analysed at a minimum of one year.

Acute THA had a 7.5% one-year mortality rate compared with 2.5% in the OA group (p < 0.01). The revision rate was 2.5% vs 1.8% in the acute and OA groups respectively. The dislocation rate was 4.3% for the whole group with a 8.5% for the acute group and 3.5% for the OA group (p< 0.01). In the acute group the dislocation rate using the posterior approach was 17.1 % compared to 3.1% for the lateral approach (p< 0.01).

We conclude that acute THA is a useful procedure in fit patients with a fracture of the neck of the femur but that a posterior approach should be avoided.

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.

Introduction: It is well documented that surgery following hip fractures (#NOF) has accepted failure rates of between four and 33%. An average of 120 patients are admitted to Wellington hospital for #NOF each year.

Aim: We aimed to identify the rate of and reasons for readmission for further surgery within a year of #NOF in patients admitted to Wellington hospital.

Methods: A list of all patients admitted for surgical treatment of hip fractures during 1998 and 1999 was obtained from the hospital database. Demographic data, type of fracture, surgical intervention, readmission for surgery on the same hip and subsequent surgical intervention for each patient were noted.

Results: Of the 209 patients who underwent surgery for 215 fractures, 55% (n=119) sustained subcapital, 43% (n=92) intertrochanteric and 2% (n=4) other fractures. Seven percent (n=15) were readmitted for a second hip operation within twelve months. Eighty percent (n=12) of those who were readmitted had sustained sub-capital fractures. Of those in the readmission group primary surgery comprised ORIF with cannulated screws (40%), compression screw with or without one cannulated screw and plate (40%), hemiarthroplasty (HA) (13%) and total hip arthroplasty (THA) (7%).

For patients who had sustained a subcapital fracture (n=117), 21% (P< 0.05) of those who had been treated with cannulated screws required further surgery compared with 2–14% who had the other types of surgery.

Conclusions: Rates of readmission for further hip surgery following hip fracture in Wellington hospital appear to be in the lower range of those reported elsewhere.

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.

Aim: To determine the incidence of periacetabular osteolysis in an uncemented, press-fit, one-piece, titanium plasma spray backed acetabular cup used in conjunction with a cemented or uncemented femoral component followed for 10 years.

Method: Patients undergoing primary total hip arthroplasty in 1989 were reviewed and new radiographs obtained. These were compared with the initial post-operative radiographs and the presence of osteolysis in the three zones of Delee and Charnley were recorded.

Results: Of 57 patients, 14 were deceased at the time of follow-up and nine were lost to follow-up. Ten patients had undergone revision for problems related to the femoral stem. There was only one possible case of periacetabular osteolysis seen in this series. In this case the lytic lesion was seen on the early post-operative radiograph and did not change in 10 years, and thus may not have been osteolysis.

Conclusions: The reported incidence of periacetabular osteolysis with two-piece cups varies between 30 and 50%. Thus, this cup has an extremely low possible osteolysis incidence. This study raises the wisdom of the continued use of two piece cups of any design.

Aim: To ascertain whether there is a relationship between time to surgery and mortality in hip fracture patients.

Method: The records of 120 patients admitted with hip fractures were examined. The approximate time of injury, the time of admission to hospital, the time of surgery, the number of medical co-morbidities, the A.S.A. grade, age, and length of hospital stay, were recorded. Death statistics were obtained from the Registrar of Births Deaths and Marriages. An analysis was then performed to assess the presence of correlation between time from injury to surgery, time from admission to surgery and three and six-month mortality in patients who were A.S.A. grades two or three.

Results: Preliminary analysis of the data showed a strong correlation between time from injury and the time from admission, to surgery and subsequent death. When these times exceeded 24 hours the mortality increased.

Conclusion: This study suggested that every effort should be made to operate on patients with hip fractures within 24 hours of admission to minimise mortality resulting from this injury.

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

Method: Seven adult mongrel dogs underwent staged bilateral total hip replacement. On one side the cement was packed into the femur with a finger while on the opposite side the femoral canal was washed, brushed, distally plugged and injected with cement under pressure before inserting the femoral component. Sequential fluorochrome bone labelling was performed. The dogs were sacrificed up to six months after the surgery. Undecalcified 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 apposition 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 suggested 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.

Aim: The direct lateral approach, as described by Hardinge et al, may have the advantage of reducing the incidence of dislocation after total hip arthroplasty. The purpose of this paper is to describe a modification of the direct lateral approach used by the author on consecutive total hip arthroplasty for all patients; including primary arthritis, fractures and revisions over a period of five years. The incidence and causes of complications, specifically dislocation, is discussed.

Method: A modification of the direct lateral approach, where gluteus minimus is split anteriorly rather than being detached from the greater trochanter, is described. This approach allowed its primary repair during wound closure, reducing surgical dead-space and theoretically reducing the incidence of dislocation. The records of all patients in whom the author performed this approach for total hip arthroplasty between 1 February 1994 and 1 February 1999 were examined. Patients were routinely seen at one year after operation and any early complications of surgery recorded. Minimum follow-up for this series was one year.

Conclusion: This modification of the direct lateral approach which preserves the integrity of gluteus minimus while still allowing adequate exposure and is extensile, gave a very acceptable incidence of dislocation in total hip arthroplasty for degenerative disease, fracture, and revision cases.

Introduction: Ultra high molecular weight polyethylene (UHMWPE) wear debris generated at the articulating interface of total hip arthroplasties continues to be the major cause of early failure of these implants.

Aim: To validate the accuracy and reproducibility of the three-dimensional technique (3D) of in vivo measurement of UHMWPE wear using PolyWare ™ when applied to digitised radiographs. The aim was to keep the cumulative errors below the accepted annual linear wear rate of 0.15 mm.

Method: Using precision phantoms with known cup and head sizes and known deviation simulating wear, series of x-rays were taken simulating a number of variables. These variables were grouped into: patient variables (centering, exposure, motion artefact, prosthesis orientation), image acquisition variables (film and cassette type, x-ray exposure, non-circularity of the projected image, magnification, image sharpness), digitisation variables (input resolution, sharpness), and errors inherent to the PolyWare™ software analytical process.

Results: Patient factors contributed the largest errors to the process – these were highly variable. Exposure and input resolution also contributed errors to a lesser extent. No significant error introduction was found with regard to any of the other above-mentioned factors, in particular the PolyWare™ analysis.

Conclusions: The three dimensional method (PolyWare™) is accurate and highly reproducible. Apart from patient factors, which directly and indirectly introduce errors, this method is a satisfactory means of estimating the in vivo wear of UHMWPE.