Measuring the migration of the components and polyethylene wear after total hip arthroplasty: beads and specialised radiographs are not necessary.

AIMS: This paper describes the methodology, validation and reliability of a new computer-assisted method which uses models of the patient's bones and the components to measure their migration and polyethylene wear from radiographs after total hip arthroplasty (THA). MATERIALS AND METHODS: Models of the patient's acetabular and femoral component obtained from the manufacturer and models of the patient's pelvis and femur built from a single computed tomography (CT) scan, are used by a computer program to measure the migration of the components and the penetration of the femoral head from anteroposterior and lateral radiographs taken at follow-up visits. The program simulates the radiographic setup and matches the position and orientation of the models to outlines of the pelvis, the acetabular and femoral component, and femur on radiographs. Changes in position and orientation reflect the migration of the components and the penetration of the femoral head. Validation was performed using radiographs of phantoms simulating known migration and penetration, and the clinical feasibility of measuring migration was assessed in two patients. RESULTS: Migration of the acetabular and femoral components can be measured with limits of agreement (LOA) of 0.37 mm and 0.33 mm, respectively. Penetration of the femoral head can be measured with LOA of 0.161 mm. CONCLUSION: The migration of components and polyethylene wear can be measured without needing specialised radiographs. Accurate measurement may allow earlier prediction of failure after THA. Cite this article: Bone Joint J 2017;99-B:1290-7.

Noise from total hip replacements: a case-controlled study.

OBJECTIVES: Our study aimed to examine not only the incidence but also the impact of noise from two types of total hip replacement articulations: ceramic-on-ceramic and ceramic-on-polyethylene. METHODS: We performed a case-controlled study comparing subjective and objective questionnaire scores of patients receiving a ceramic-on-ceramic or a ceramic-on-polyethylene total hip replacement by a single surgeon. RESULTS: There was a threefold higher incidence of noise from patients in the ceramic-on-ceramic group compared with the control group. The impact of this noise was significant for patients both subjectively and objectively. CONCLUSIONS: This study reports a high patient impact of noise from ceramic-on-ceramic total hip replacements. This has led to a change in practice by the principal author. Cite this article: Bone Joint Res 2014;3:183-6.

Mobile- versus fixed-bearing modern total knee replacements- which is the more patella-friendly design?: The 11-year New Zealand Joint Registry study.

OBJECTIVES: Our study aimed to examine if a mobile-bearing total knee replacement (TKR) offered an advantage over fixed-bearing designs with respect to rates of secondary resurfacing of the patella in knees in which it was initially left unresurfaced. METHODS: We examined the 11-year report of the New Zealand Joint Registry and identified all primary TKR designs that had been implanted in > 500 knees without primary resurfacing of the patella. We examined how many of these were mobile-bearing, fixed-bearing cruciate-retaining and fixed-bearing posterior-stabilised designs. We assessed the rates of secondary resurfacing of the patella for each group and constructed Kaplan-Meier survival curves. RESULTS: Our study showed a significantly higher rate of revision for secondary resurfacing of the patella in the fixed-bearing posterior-stabilised TKR designs compared with either fixed-bearing cruciate-retaining or mobile-bearing designs (p = 0.001 and p = 0.036, respectively). CONCLUSIONS: This New Zealand Registry study shows that during the last 11 years, revision procedures to resurface an unresurfaced patella in primary TKR occurred at a higher rate in fixed-bearing posterior-stabilised designs.

Waiting for hip arthroplasty: economic costs and health outcomes.

This prospective cohort study of 153 patients aimed to determine the economic and health costs of waiting for total hip arthroplasty (THA). Health-related quality of life, using self-completed WOMAC and EQ-5D questionnaires, was assessed monthly from enrolment preoperatively to 6 months postsurgery. Monthly cost diaries were used to record costs. The mean waiting time was 5.1 months and mean total cost of waiting for surgery was NZ 4305 dollars(US 2876 dollars) per person (pp) (NZ 1 dollar = US 0.668 dollar). Waiting more than 6 months was associated with a higher total mean cost (NZ 4278 dollars/US 2858 dollars pp) than waiting less than 6 months (NZ 2828 dollars/US 1889 dollars pp; P < .01). Improvements from preoperative to postoperative WOMAC and EQ-5D scores were identified (P < or = .01). Waiting longer led to poorer physical function preoperatively (P < or = .01). Those with poor initial health status showed greater improvement in WOMAC (P = .0001) and EQ-5D (P = .003) measures by 6 months after surgery. Longer waits for total hip arthroplasty incur greater economic costs and deterioration in physical function while waiting.

An assessment of sleep disturbance in patients before and after total hip arthroplasty.

Patients with osteoarthritis commonly complain of sleep disturbance that may be due to pain. Osteoarthritic hip pain is commonly alleviated by total hip arthroplasty (THA). Forty-eight patients waiting for THA completed a sleep questionnaire and were monitored using actigraphy and sleep diaries for 4 to 5 nights, 1 month before and 3 months after surgery. For the group as a whole, significant improvements were seen in subjective and objective measures of sleep after THA. In this study, 75% of participants reported that their sleep was never or rarely disturbed by hip pain after surgery. Actigraphy indicated significant reductions in time in bed and activity during sleep, more efficient sleep and less fragmented (restless) sleep. Differences between patients aged < 65 and > or = 65 years were observed. These findings support the hypothesis that relief from the pain of osteoarthritis as a result of THA improves sleep quality. Improvements in sleep contribute to the improved quality of life and day-to-day functioning seen after THA.

The effect of different cement insertion techniques on the bone-cement interface.

Since the introduction of cemented total hip arthroplasty, the method of cement usage has evolved through several generations. These changes may have been responsible for an improvement in femoral component longevity. The nature of the bone-cement interface in first-generation cementing techniques has been described, but the bone-cement interface in more recent cementing techniques has not. This article describes the bone-cement interface after 2 different cementing techniques in a canine total hip arthroplasty model.

Hip fracture incidence in New Zealand, revisited.

AIM: Earlier predictions of the incidence of hip fractures in the older adult population suggested that by 2011 the rate would rise to epidemic proportions. The purpose of this study was to compare the number hip fractures occuring in New Zealand from 1988 to 1999 with the hip fracture rate predicted in 1990 by Rockwood, Horne and Cryer. METHODS: Data on the number of patients admitted to New Zealand hospitals with a diagnosis of fractured neck of femur were obtained, and compared with weighted regression and baseline predictions of Rockwood et al. RESULTS: The numbers of hip fractures for females, from 1988 to 1993, were similar to the number predicted, yet have been significantly lower than stated predictions since 1995. For males, hip fracture numbers since 1995 were less than the weighted regressions predicted (NS). CONCLUSIONS: Numbers of hip fractures since 1995 have been fewer than predicted. Possible reasons for maintaining the rates of hospitalisation due to fractured neck of femur at pre-1995 levels, are discussed.

A cardiac prevention and rehabilitation programme for all patients at first presentation with coronary artery disease.

OBJECTIVE: To develop and test a cardiac prevention and rehabilitation programme for achieving sustained lifestyle, risk factor, and therapeutic targets in patients presenting for the first time with exertional angina, acute coronary syndromes, or coronary revascularisation. DESIGN: A descriptive study. SETTING: A hospital based 12 week outpatient programme. INTERVENTIONS: A multiprofessional family based programme of lifestyle and risk factor modification. MAIN OUTCOME MEASURES: Non-smoking status, body mass index, blood pressure, plasma cholesterol, use of prophylactic drugs. RESULTS: 158 patients (82% of 194 possible cases) were recruited over 15 months, with 72% completing the programme. Targets for achieving non-smoking status, blood pressure < 140/90 mm Hg, and total cholesterol < 4.8 mmol/l were achieved in 92%, 73%, and 62%, respectively, and the proportion on aspirin, beta blockers, and lipid lowering treatment was 95%, 58%, and 64% on referral back to general practice for continuing care. CONCLUSIONS: A comprehensive cardiac prevention and rehabilitation programme can be offered to all patients presenting for the first time with coronary heart disease, including those with exertional angina who are normally managed in primary care. Lifestyle, risk factor, and therapeutic targets can be successfully achieved in most patients with such a hospital based programme.

Surgical repair for recurrent anterior instability of the shoulder.

BACKGROUND: The outcome of surgical repair for recurrent anterior instability of the shoulder at the Wellington Hospital was reviewed. METHODS: A retrospective review was undertaken of patients undergoing surgical repair for recurrent anterior instability of the shoulder at Wellington Hospital between October 1989 and November 1996. Patients were asked to complete two shoulder-specific questionnaires, and the range of motion, stability, and strength was evaluated clinically. RESULTS: A total of 37 patients (38 shoulders) who had recurrent anterior dislocation of the shoulder that was unresponsive to a physician-directed rehabilitation programme were managed with open surgical repair. Procedures included the Putti-Platt, Bristow, Magnuson-Stack, Botychev, and Bankart repairs. The mean age at the time of surgery was 24 years and the male-to-female ratio was 11.3:1. Surgery was performed on the dominant side in 63.2% of shoulders. The postoperative redislocation rate was 39.4% at an average of 4.6 years follow-up. Three patients have since required revision of their surgical repair and one patient is awaiting revision. A total of 63.2% of patients were unable to return to their previous level of sports. Differences existed between the motion in the surgically treated shoulder when compared with the contralateral side. Patients reported the most functional difficulty in throwing, working overhead, pulling, and working at shoulder level. CONCLUSIONS: The results of the present study indicate a high redislocation rate, and highlight the challenges in restoring a stable, mobile, functional shoulder.

Assessment of polyethylene wear in total hip replacement.

The three-dimensional technique is a method for the measurement of polyethylene wear in patients with total hip joint replacement. Application of image processing technology allows automation of point selection from digital images of radiographs scanned into the computer. Validation of image processing modifications reveals a three-fold increase in accuracy and a 40-fold increase in reproducibility compared with manual input of points from a digitizer during bench testing. A review of three-dimensional technique application to clinical patients gives information on the factors that influence polyethylene wear. Increasing age, activity level, femoral head size, decreasing polyethylene thickness, and insertion of total hip prostheses without cement all increase polyethylene wear. Restoration of femoral offset during total hip replacement seems to decreases polyethylene wear. No apparent difference in polyethylene wear rate could be found between two groups of patients, one group had a stainless steel-polyethylene articulation and the other had a ceramic-polyethylene articulation. Measurement of the serial polyethylene wear of individual patients reveals a high rate of femoral head penetration during the first 2 years after total hip replacement using metal-backed acetabular components inserted without cement. Interpretation of this femoral head penetration as true polyethylene wear may be erroneous, however, because creep of the polyethylene and acetabular liner movement within its metal shell cannot be measured.

Donor site morbidity in the iliac crest bone graft.

BACKGROUND: Open iliac crest bone grafting is a common surgical procedure with recognized short-term complications. The present paper documents the medium- to long-term complications and level of patient satisfaction following the procedure. METHODS: Seventy-three patients undergoing an open iliac crest bone graft over the past 6 years at Wellington Hospital were retrospectively reviewed. All patients completed a postal questionnaire which assessed their current pain, sensory changes in and below the scar, scar appearance and overall appearance with the bone graft donor site. RESULTS: Sixteen patients (21.9%) reported pain, 11 patients (15%) stated that their scar was sensitive to touch and 19 patients (22%) reported a degree of sensory change below the scar. Six patients (8.2%) felt that the scar appearance was totally unacceptable. Overall satisfaction, however, was high with 70 patients (95.8%) 'fairly satisfied' or 'totally satisfied' with their iliac crest donor site. CONCLUSIONS: Bone grafting from the iliac crest is a relatively benign procedure in terms of patient satisfaction, and the most significant morbidity is pain.

Patient perception of the ischemic arm block.

OBJECTIVE: To investigate patient perception of the ischemic arm block. DESIGN: Retrospective study. SETTING: Fracture clinic of a major city hospital. PATIENTS/PARTICIPANTS: One hundred eighty-one consecutive patients who had an ischemic arm block were mailed a questionnaire. The response rate was 71 percent. RESULTS AND CONCLUSIONS: Forty-two percent of respondents reported significant pain from the tourniquet cuff, and 29 percent reported significant pain during manipulation or within the first hour after releasing the cuff. Statistical analysis showed that cuff pain was independent and not indicative of increased individual sensitivity to pain. Manipulation pain was likewise an independent phenomenon. There was a close relationship between manipulation pain and postprocedure pain. Reported complications were rare. Fourteen percent were dissatisfied with the procedure, which correlated with manipulation pain but not with cuff pain. In conclusion, significant cuff pain during the procedure is common. Manipulation pain is not as common but may lead to dissatisfaction.

Measurement of polyethylene wear in acetabular components inserted with and without cement. A randomized trial.

We measured the three-dimensional wear of polyethylene after total hip arthroplasty with a titanium metal-backed Mallory-Head prosthesis that was inserted with cement in sixty-nine patients (sixty-nine hips) and with a press-fit titanium metal-backed Mallory-Head prosthesis that was inserted without cement in seventy patients (seventy hips). A modular titanium femoral head was used in all of the hips. The patients in the present study were part of a larger double-blind randomized trial comparing the result of total hip arthroplasty performed with cement with that of the same procedure performed without cement in 250 patients. The criterion for inclusion in the study of polyethylene wear was a minimum duration of follow-up of four years, which was met by 148 patients. As adequate radiographs for digitization were not available for nine patients, 139 patients were included in the present study. The age of the patient, the postoperative Harris hip score, the diameter of the femoral head, the thickness of the liner in the polar region of the acetabular component, and the duration of follow-up were similar for the two groups. The mean rate of volumetric wear of the polyethylene was significantly greater in the prostheses that had been inserted without cement than in those that had been inserted with cement (155.1 cubic millimeters per year compared with 98.5 cubic millimeters per year; p = 0.000008). Thirty-four (49 per cent) of the seventy hips in which the prosthesis had been inserted without cement had evidence of osteolysis on radiographs, compared with twelve (17 per cent) of the sixty-nine hips in the other group (p = 0.0002). Osteolysis was associated with an increased rate of polyethylene wear only in the hips in which the prosthesis had been inserted without cement.

Three-dimensional polyethylene wear of a press-fit titanium prosthesis. Factors influencing generation of polyethylene debris.

Between 1985 and 1990, 108 consecutive Harris-Galante I (Zimmer, Warsaw, IN) total hip arthroplasties were performed by four surgeons at a single hospital. At the time of follow-up evaluation, 80 hips were available for review. The mean rate of linear wear was 0.15 mm/y, mean rate of three-dimensional femoral head displacement was 0.21 mm/y, and mean rate of volumetric wear was 121 mm3/y. Eight hips (10%) in this series had radiologic osteolysis around either the femoral or acetabular component. A significantly greater volumetric wear rate was found in patients who were younger, those with a higher activity level, those who received a 32-mm-diameter femoral head, and those with vertical orientation of their acetabular component. No relationship could be made with patient weight, gender, Harris hip score, or cup diameter.

Forearm and wrist fractures in mountain bike riders.

AIMS: To identify the different types of fractures of the forearm caused by mountain bike accidents, and to assess the physical and social consequences of these injuries. METHODS: All the forearm fractures recorded in the Wellington Hospital fracture logs between July 1992 and July 1994 were reviewed in December 1994. Mountain bike accidents were identified in 37 patients. 11 patients could not be contacted and one patient declined participation, leaving 25 patients who participated in the study. Those who took part each completed a questionnaire and were examined. The radiographs of each patient were also reviewed. RESULTS: Nine of the fractures occurred in the proximal third of the forearm and 16 occurred in the distal third. The most common fracture was that of the radial head (9). When functionally assessed 15 patients were graded excellent, 5 satisfactory, 4 unsatisfactory, and 1 patient was graded as poor. The average time off work was 28 days, with no change of occupation being necessitated in any of the patients. Eight patients had to make changes to their recreational activities. CONCLUSIONS: The results of the study suggest that mountain bike accidents can result in significant injury. With adequate medical attention it appears that the majority of cases recover well, and experience only minimal discomfort without significant long term physical and social consequences.

A selective treatment approach to supracondylar fracture of the humerus in children.

The results of a "selective treatment" policy applied to 176 patients presenting with supracondylar fracture of the humerus are analyzed. As initial treatment 148 patients underwent closed reduction and casting, seven closed reduction and pinning, 17 olecranon traction, and four open reduction and pinning. Analysis of patients by fracture type and initial treatment demonstrated a satisfactory outcome in 46 of 75 type III fractures and in 37 of 48 patients with type II fractures treated by closed reduction and casting. Thus a policy of initially pinning all such type III fractures in our unit would mean that 61% of such fractures would be pinned needlessly. Of type II fractures 77% would be needlessly pinned if such a policy was applied to type II fractures. The current trend towards pinning of all type III supracondylar fractures is not supported by the data from this study.

Osteosarcoma in New Zealand 1981-7: an overview.

AIMS: To examine the incidence, and results of treatment of osteosarcoma in New Zealand between 1981 and 1987. METHOD: Data was obtained from the Cancer Registry for all patients registered with osteosarcoma between 1981 and 1987. RESULTS: There were 104 patients in the study group. There was a peak incidence in the second decade with a second smaller peak in the seventh and eight decades. The overall 5 year survival rate was 29%. For the group aged under 30 years there was a 44% 5 year survival rate. Those aged over 60 years had a 3.2% 5 year survival. Survival rates were better when treated with surgery and chemotherapy and where the tumour was of the appendicular skeleton. CONCLUSION: This is a mixed group of patients. The 5 year survival rates appear to be at the lower end of the spectrum of the results reported for similar groups in other countries.

Measurement of polyethylene wear in metal-backed acetabular cups. I. Three-dimensional technique.

A new technique, the 3-dimensional technique, has been developed. Using a digitzer, points taken from anteroposterior and lateral radiographs are input into a personal computer. A 3-dimensional solid model of the prosthesis is created using custom software. Tilt and anteversion of the acetabular cup are measured, and the model is rotated to a standard frontal view, allowing measurement of femoral head displacement from the center of the acetabular cup. Comparing serial radiographs of the same patient gives the direction and distance of femoral head displacement over time, and this value is used to calculate the minimum volume of polyethylene debris generated. The 3-dimensional technique has been validated by construction of a precision acrylic phantom, and milling of a metal-backed acetabular cup to simulate polyethylene wear. Three-dimensional measurement of femoral head displacement using this technique has an accuracy of +/- 0.15 mm, and volume calculations are within 8% of the true amount of polyethylene removed from the cup. The 3-dimensional technique gives previously unavailable information, and can be used for clinical evaluation of polyethylene wear and evaluation of new prosthetic designs and bearing surfaces.

Measurement of polyethylene wear in metal-backed acetabular cups. II. Clinical application.

The new 3-dimensional technique was applied to the radiographs of 141 patients who had received Porous Coated Anatomic total hip prostheses. Values were obtained for the position of the acetabular cup, the 3-dimensional distance and direction of femoral head displacement, and the minimum volume of polyethylene debris produced. Mean age of the patients at the time of replacement was 61 years old; mean followup was 5.6 years (range, 4-7.2 years). Change in the position of the femoral head between initial and long-term followup films was assumed to represent polyethylene wear, and formulas were used to calculate the minimal volume of polyethylene debris produced. The overall rate of 3-dimensional femoral head displacement was 0.264 mm per year, almost twice that usually quoted in the current literature for 2-dimensional linear wear. A significant contribution to this value was made by anterior and posterior displacement. Two-dimensional femoral head displacement (measured in the plane of anteroposterior radiographs) on the same patients was 0.149 mm per year. The mean minimum volume of polyethylene debris produced after 5.6 years was 0.448 cm3 (range, 0.00-2.83 cm3), giving a mean rate of 0.079 cm3 polyethylene debris produced each year. Thirteen patients in this series had radiologic osteolysis and a significantly greater femoral head displacement and polyethylene volumetric wear than those with no osteolysis. Patients with a 32-mm femoral head diameter and a polyethylene linear < 1 cm thick had a significantly greater amount of polyethylene wear. This series gives previously unavailable data on 3-dimensional femoral head displacement and is the first report that correlates the minimum volume of polyethylene wear produced with radiologic osteolysis.