Summary Statement

We analysed impaction bone grafting used together with cemented or uncemented fixation in acetabular revision surgery. The overall risk for re-revision did not differ between the cemented and uncemented group. However, aseptic loosening was more common in the cemented group.

Introduction: Revision rate after THA in the younger age groups is still unacceptable high and might up to 20% after 10 years. The aim of this investigation is to evaluate risk factors for later revision in patients younger than 50 years at surgery based on the NARA database (Nordic Arthroplasty Register Association).

Materials and Methods: 14,610 primary THA from Denmark, Sweden, and Norway, operated from 1995 to 2007, were included. 49.4% was males, the diagnosis was idiopathic osteoarthrosis (OA) in 46%, childhood disease in 26%, inflammatory arthritis (IA) in 12%, non-traumatic osteonecrosis in 9% and fracture in 6%. 49% of the THA’s were uncemented, 27% cemented, 14% hybrid, and 8% were inverse hybrid THA’s. Cox multiple regression, adjusted for diagnose, age, gender, calendar year and surgical approach, was used to calculate prosthesis survival with any revision as end-point. RR= relative risk (CI= confidence interval).

Results: The overall 10-year survival was 83%. There was no difference between gender (RR=0.94 (0.82–1.07)). IA had a 37% reduced risk of revision compared with OA (RR=0.67 (0.54–0.84)), whereas there was no difference between childhood disease and primary osteoarthrosis. Overall, cemented, uncemented and reverse hybrid THA had a better survival than hybrid THA. Hybrid THA had 24% increased risk compared with cemented (RR=1.24 (1.04–1.49)). There were no difference between cementless and cemented (RR=1.07 (0.92–1.26)). Interestingly, the inverse THA had lower revision rate than cemented THA in men (RR=0.50 (0.25–0.99)). The risk for revision due to aseptic loosening was lowest in cementless THA and reduced to RR=0.55 (0.44–0.69) compared with cemented THA.

Discussion: and Conclusion: Choice of prosthetic concept for younger patients is still of debate. The present study including only patients younger than 50 years of age, showed that overall cemented, uncemented and reverse hybrid THA, had better survival than traditional hybrid. The risk for revision due to aseptic loosening was higher in cemented than cementless THA.

Introduction: There is an increasing interest in surface replacement arthroplasty (SRA) as an alternative to conventional THA (cTHA) in young and active patients. However, there has been considerable variability in reported outcomes. National joint registry reports have shown increased revision rates compared to cTHA. We analysed outcome measured as non-septic revision rate within two years for SRA in the NARA data base (Nordic Arthroplasty Register Association).

Materials and Methods: 1638 SRA and 163802 cTHA with age up to 73 years and a non-fracture diagnosis, operated from 1995 to 2007, were compared using Cox multiple regression including age, gender, diagnosis, nation and prosthesis type with cTHA divided into cemented, uncemented, hybrid and reversed hybrid fixation. Men below 50 years of age (460 SRA and 7185 cTHA) were analysed as a subset. The SRA cohort with a mean follow-up 1,8 years was also analysed with the same method including age, gender, diagnosis, number of performed SRA per hospital and the four most commonly used prosthesis designs. In an additional analysis femoral head diameter was added, reducing the number of cases to 1552. results are presented as relative risk (RR) with 95 % confidence interval(CI).

Results: SRA had a more than twofold increased revision risk compared to cTHA, RR=2,50 (1,67–3,70), which increased to 3,63 (2,42–5,44) when compared with all cemented THA. In the subpopulation of men below 50 years of age, there was no difference between SRA and any of the cTHA cathegories. Within the SRA group RR was reduced by male gender, RR=0,46 (0,25–0,86), in hospital performing > 70 SRA (RR=0,26, 0,11–0,60) and with use of BHR (Birmingham Hip Resurfacing) compared to all other designs (RR=0,27, 0,12–0,61). The size of the femoral head diameter had no significant influence on the early revision rate.

Discussion and Conclusion: Surface replacement arthroplasty has an increased risk of early revision compared to conventional and cemented THA except for men below 50 years of age. There is a learning curve on the hospital level. Cases with secondary osteoarthritis were comparatively few and were mainly caused by pediatric hip disease. SRA might become an alternative for young men, but our follow up is too short to determine if this indication remains in the longer perspective.

Introduction: Up to now comparisons and pooling of data between the Scandinavian arthroplasty registers have been restrained by use of separate and incompatible data systems.

Purpose: To create a common Scandinavian database for hip arthroplasties and to compare demographics and results between the Scandinavian countries.

Materials and methods: For this study we selected primary total hip prostheses (THR) from 1995–2006. A common code set was made, and after de-identification of the patients’ identity, including deletion of the national civil registration numbers, Denmark, Sweden, and Norway delivered data. Kaplan-Meier and Cox multiple regression, with adjustment for diagnosis, age, and gender, were used to calculate prosthesis survival, with any revision as end-point.

Results: 280,201 operations were included (Denmark 69,242, Sweden 140,821, Norway 70,138). Female patients constituted 60% in Denmark and Sweden and 70% in Norway. In Denmark, Sweden, and Norway childhood disease constituted 3.1%, 1.8%, and 8.7% respectively. The posterior approach was used in 91% of cases in Denmark, 60% in Sweden, and 24% in Norway. Cemented THRs were applied in 46% of patients in Denmark, 89% in Sweden, and in 79% in Norway. Resurfacing hips constituted 0.5% or less in all countries.

9,596 of the 280,201 primary THRs, had been revised. Ten-years survival was 91.9% (95% CI: 91.5 – 92.3) in Denmark, 93.9% (95% CI: 93.6–94.1) in Sweden, and 92.6% (95% CI: 92.3–93.0) in Norway.

In Sweden and Norway 23% of revisions were due to dislocation, compared to 34% in Denmark. Replacement of only cup or liner constituted 29% of the revisions in Sweden, 33% in Norway, and 44% in Denmark.

Conclusion: This unique database is now functioning, and has showed differences among the countries concerning demographics, prosthesis fixation, prosthesis survival, and reasons for revisions. The large number of THRs in this database significantly enhances our perspectives for future research, especially in diagnostic- and treatment groups with too small numbers in each separate

Background: Hemiarthroplasty of the hip is a common procedure, but information about implants and outcome is scarce. In Sweden the number of hemiarthroplasties has increased from 200 in 1998 to 4181 in 2007.

Material and Methods: Nationwide registration started in 2005. 100% of the hospitals participates, and 96% of the hemi-procedures are registrered. An analysis of 12 245 cases operated 2005–07 is presented.

Results: In the Register the mean age at surgery is 84 years (SD 7.0, 73% female). 93% are operated due to acute fracture and 6% due to failed internal fracture fixation. Cemented fixation has been used in 92% and a posterior approach in about half of the cases (52%). The Lubinus and Exeter stems are most common (41 and 23%). The Austin-Moore design has decreased from 9 to 2% during the study period.

3.2% of the patients (hips) have been reoperated, most commonly because of dislocation. Multiple reoperations are common. Male gender, secondary procedure and uncemented stem are associated with increased reoperation risk with 1.2, 1.7 and 1.8 times (1.2, CI: 1.0–1.6; 1.7, 1.3–2.3; 1.8 1.4–2.5). Use of uncemented fixation resulted in increased risk of reoperation, also with exclusion of uncemented Austin-Moore prostheses (1.8 times, 1.1–2.8).

In a separate analysis of the two most frequent designs, use of bipolar head increased the risk of revision twice (1.4–2.8) compared to unipolar head when adjusting for other risk factors. This may reflect that fitter and more active individuals get a bipolar prosthesis and are more prone to become revised should complications occur or a true increase of complications when using bipolar head. A further analysis is in progress.

Use of dorsal approach (1.6, 1.2–2.2), Austin-Moore (1.8, 1.1–3.1) and Thompson prostheses (1.8, 1.5–2.8) increased the risk of revision because of dislocation.

Summary: When treating fracture patients with hemi-arthroplasty we recommend that a well documented cemented implant with different off-set options should be used via an anterolateral approach. Use of bipolar heads may increase the risk of revision.

Introduction: Many patients eligible for hip arthroplasty suffer from bilateral hip disease with indication for bilateral total hip replacement (BTHR). Traditionally two-stage BTHR is far more common than one-stage procedure due to the risk of complications. However, most studies are in favour of one-stage BTHR in the healthy and young people. This study was designed to further analyse mortality, outcome, complications and cost-effectiveness after one-stage BTHR surgery.

Patients and Methods: In this prospective matched control study we examined 32 patients with BTHR hybrid surgery. The control group of 32 patients with unilateral hybrid THR was derived from Sahlgrenska University hospital. The follow up time was 1 year. Medical records, cost per patient database, records from Swedish Social Insurance Administration and HRQoL outcome measurements from the Swedish Hip Arthroplasty Register were used for the analyses.

Mortality data from the Register regarding all 950 patients with one-stage BTHR surgery during the period 1992 until 2005 were compared to those 2577 who had had a twostage procedure with less than six months between the operations.

Preliminary Results: There were no major differences in complications. The intraoperative bleeding was higher in the BTHR patients and they required more blood transfusion. Length of hospital stay was in average 10,2 days for the one-stage BTHR group and 7,6 days for the unilateral group. Preoperative EQ-5D index was 0,14 in the BTHR group and 0,31 in the control group. Mean EQ-5D gain after 1 year was 0,77 and 0,40 respectively. Hospital costs were only 60% higher in the one-stage BTHR group. Among the employed patients there were no differences in days of sick pay and cost of sick pay in the two groups. Among the 950 subjects with one-stage BTHR surgery, the 90 day mortality was 0,32% compared to 0,42% in the group of 2577 patients with two-stage procedure.

Discussion: In healthy patients with bilateral hip disease requiring bilateral arthroplasty one-stage BTHR is highly cost-effective and safe. There is even lower 90 day mortality for the onestage operated subjects in the register but this is probably due to a natural selection of younger and healthier patients. The one-stage procedure reduces the total time of rehabilitation which is of particular importance for people in working age. Cautiously estimated, performing another 100 one-stage BTHR per year instead of two-stage procedure would save 16–20 million SEK yearly in Sweden.

In a previous report from a randomised study we reported excellent fixation and less proximal periprosthetic bone mineral loss around the Epoch design at 2 years follow-up when compared with a solid stem of similar design. We now present the 7 years follow-up.

Forty consecutive patients (20 men, 10 women, mean age 57, 41–74) with non-inflammatory osteoarthritis were randomised to receive either a cementless porous-coated composite stem with reduced stiffness (Epoch) or a cementless stiff stem with a porous coating (Anatomic). Patients were followed for 7 years with repeated evaluations using radiostereometry, DXA, conventional radiography and Harris Hip Score (HHS).

At 7 years 1 stem had been revised (Anatomic) due to late infection. Subsidence and stem rotations were close to zero without any difference between the two groups (p> 0,12). Median wear rates were lower than expected (0.4mm up to 7 years) for both stem designs. At 2 years loss bone mineral density was less in Gruen regions 1, 2, 6 and 7 for the Epoch stems (p< 0.04), but this difference tended to disappear with time. At 7 years only the calcar region (Gruen region 7) had significantly denser bone in the Epoch group (p< 0.001). The HHS scores did not differ (median 98, 51–100). No stem was radiographically loose.

The Epoch stem achieved excellent fixation. Wear rates were low despite use of conventionally gamma-sterilised polyethylene. This low modulus stem had positive effects on early proximal bone remodeling, but this effect decreased with time.

INTRODUCTION: The postoperative periprosthetic femoral fracture is a severe complication after total hip surgery. It has become the third most common reason for revision. Three-hundred and twenty one fractures operated during 1999–2000, were followed in a prospective nationwide study. The study focused on the failure rate, patient satisfaction, treatment and radiographic evaluation.

PATIENTS AND METHODS: During 1999–2000, 230 fractures after a primary THR and 91 after a revision THR were reported to the Swedish National Hip Arthroplasty Register. All hospital records were collected. At follow-up the Harris hip score, a health-related quality of life measure (EQ-5D) and patient satisfaction were used as outcome measurement. A radiologist performed the radiographic evaluation.

RESULTS: A high number of patients had a loose implant at fracture time (66% in the primary group and 51% in the revision group). Eighty-eight percent of the fractures were classified as Vancouver type B fractures. A major finding was the association between the type of implant and the risk of a periprosthetic fracture. The Charnley and the Exeter prostheses were significantly over represented among patients with fractures and the Lubinus prosthesis significantly under represented. The surgeons grading of the Vancouver type B1 fracture was not in agreement with the study radiologist in more than 34% of the cases. Patient’s satisfaction concerning mobility, self-care, normal activities, pain and anxiety compared to an age matched population with a THR were poor. There was a high failure rate and by December 31, 2004, 22% had been reoperated.

DISCUSSION: A recommendation is to follow all THR patients with regularly radiographic monitoring and to intervene before the fracture. Implant related factors have to be considered when choosing implant for routine use. Difficulty in evaluating the x-rays concerning the stability of the prostheses might lead to sub optimal treatment. We recommend exploration of the implant for all patients with a Vancouver type B fracture if there is any doubt about the fixation status.

Introduction: The annual wear rate in polyethylene articulations should be 0.1 mm or less to avoid future osteolysis. Highly Crosslinked polyethylene demonstrates 80–90% wear reduction in hip simulator testing, but the clinical documentation of this new polyethylene is still inadequate. We evaluated the highly crosslink PE in two prospective randomised clinical studies. Patients and Methods: Thirty two patients (12 male, 20 female, 64 hips) with a median age of 48 years (range, 29–70 years) with bilateral primary or secondary arthrosis of the hip received hybrid THA. With liners made of highly cross-link on one side and conventional PE on the other one. Twenty-seven patients in this study have passed 2 years follow up. Further Sixty patients (61 hips) with a median age of 55 years (range, 35–70 years) were randomized to receive either highly crosslink or conventional cemented all PE of the same design. Forty-nine patients have been followed for 3 years. In both studies all patients received Spectron stems with 28mm cobalt-chromium head. Radiostereometric examinations with the patient supine or standing were done at regular intervals. Wear was measured in the supine position from the postoperative week, whereas standing examinations were initiated three months after the operation. Results: The penetration rate was almost identical in the study and control groups in 6 months after the operation. Thereafter the penetration rate levelled out in the 2 groups with highly crosslink PE. At two years the highly crosslink PE liner showed 62% lower proximal penetration and 31% lower total (three-dimensional) penetration when the patients were examined in supine position. The highly crosslink all PE cemented cups showed significantly lower proximal penetration in both position. Discussion: The better wear performance of highly crosslink PE could increase the implant longevity. Longer follow up is needed to evaluate if this new material is associated with less occurrence of osteolysis.

Aims: The aim of this study was to evaluate a highly cross-linked polyethylene WIAM in cemented hip arthroplasty. This new polyethylene has been resistant to wear in laboratory tests. Methods: 60 patients (30 women, 30 men) with a median age of 55 years (35–70) and a median weight 82 kg (47–120) were included. All patients received a Spectron femoral stem with a 28 mm head in chrome-cobalt. The patients were randomised to acetabular cups made of either WIAM (electron beam irradiation 9.5 Mrad) or conventional polyethylene (CP) sterilized in inert atmosphere. Radiostereometric examinations (supine) were done 7 days after the operation and after 3, 6 12 and 24 months. Examinations (standing) were performed at 3, 6 12 and 24 months. The migration of the femoral head centre in relation to the polyethylene marker represented the femoral head penetration. Results:. 43 hip (19 WIAM 24 CP) were available for 24 months FU. There were no differences in cup migrations between the two groups. The mean proximal penetration (supine and standing) was less than 0.2 mm at 24 months in both groups p> 0,06 Conclusions: The femoral head penetration during the first two years may be dominated by creep. There is tendency for lower proximal penetration at standing examination in the WIAM group. Futher studies and longer follow up is necessary until highly crosslink polyethylene can be recommended for general use.

Aims: In 1979 a national observation study of total hip arthroplasties was started in Sweden. The Swedish Hip Register describes the epidemiology of primary and revision surgery and identifies risk factors for failure. Every unit reports details concerning implants, surgical and cementing technique and revision procedures online via the Internet home page (www.jru.orthop.gu.se). Methods: Currently the register contains 203 625 primary total hip arthroplasties performed during 1979–2001 and 18 067 revision procedures. Revision is the failure endpoint definition and modified Kaplan-Meier statistics and Poisson models are used for survival analysis. Each hospital receive their results annually providing a system for continuous improvement. Results: The results show that serious complications have declined significantly despite an increasing number of patients at risk. The revision burden for cemented THR (94% of the implants are cemented) is only 7.5%, which is much lower than in other countries. Over the 22 year period revision for aseptic loosening has been reduced to one quarter. Demographics are important since male gender and young age significantly increase the risk for revision. Cementless implants have in general had a worse outcome than expected but improved during the last decade. Conclusion: Problem areas are the young population and revision surgery which must be improved. The revision burden is about two times higher in all other countries. This finding implies that the register is extremely cost-effective and the reduction in direct costs for the health care service in Sweden corresponds to approximately USD 140 millions over the last ten years.

Introduction: In a pioneer study Oonishi et al (1988) found reduced socket wear with the use of polyethylene subjected to high radiation doses. This observation has stimulated the development of a new generation polyethylene. In addition to high radiation doses the plastic is also subjected to various types of heat treatment to reduce the amount of free radicals. The purpose of the present study is to evaluate one of the new highly cross-linked polyethylenes in a randomized controlled study of cemented THA. The hypothesis is that the improved wear resistance will reduce the prevalence of osteolytic lesions with long-term follow-up.

Methods and materials: Patients in clinical and radiographic need of a THR with non-inflammatory osteoarthritis of the hip were randomized in two groups. Group 1 received a cemented Weber cup (Sulzer®, Switzerland) made of highly cross-linked (WIAM) polyethylene, group 2 got a conventional cup. All patients received a cemented Spectron (Smith & Nephew, USA) with a 28mm cobalt-chromium head.

So far 15 patients, (6 male and 9 females) with a median age of 55 years (range 42–62) have been evaluated in group 1 and 14 (9 male and 5 females) with a median age of 55 years (range 45–70) in group 2. The penetration of the femoral heads has so far been measured postoperatively (all hips supine), after 3 month (17 hips supine and standing) and after 6 month (11 hips supine and standing) using radiostereometry.

Results: The median proximal and three-dimensional (3-D) penetration (total wear) 0–6 month (supine position) was almost equal in the two groups. Group 1 had a proximal penetration of 0.08 mm (range 0.00–0.17) and a total penetration of 0.11 mm (range 0.06–0.14). The corresponding values for group 2 were 0,10 mm (0.05–0.21) for proximal penetration and 0.13 mm (0.10–0.16) for total penetration. Between 3 and 6 month the penetration (median values) was 0.04 mm/0.10 mm (proximal/3-D) for group 1 and 0.07 mm/0.12 mm for group 2. With the patients standing we found a proximally migration of the socket (0–6 month) in group 1 of 0,08 mm (−0.07 – 0.21) and 0.12 mm (0.1–0.13) in group 2.

Discussion: Use of a highly cross-linked polyethylene in the socket did not influence the early penetration rate after THR. Early creep of the material is possible explanation.

1-year follow-up on approximately 50% of the patients will be presented at the meeting.

We assessed 100 patients with a primary total hip replacement using the Harris hip score and the Nottingham Health Profile at one, three and five years after operation. They were derived from two prospective randomised series of cemented and uncemented replacements.

Both scoring systems correlated highly and were each heavily influenced by the system of functional classification defined by Charnley. After five years both reflected the function of the implant and the general state of the patient. A higher degree of sensitivity is needed to show differences in the performance of an implant in the short and medium term. We do not yet have an ideal system of clinical assessment and the overall function must always be properly assessed.

We enrolled 98 patients (107 hips) with a mean age of 47 years (SD 8.6) into a prospective study of the Madreporic Lord THR; 34 hips had primary and 73 secondary osteoarthritis.

After ten years, the survival rate using revision as the endpoint for failure was 70% (±9) for the cup and 98% (±0.3) for the stem. The combined clinical and radiological survival rates were 46% (±11) and 81% (±10), respectively. Osteoporosis due to stress-shielding was observed in the proximal femur. Hips with radiologically dense bone postoperatively showed the most pronounced bone loss.

We recommend continued radiological follow-up of patients with this type of implant to allow revision to be performed before there is severe bony destruction of the pelvis.

The tibial components in 143 patients with total knee replacements performed before 1988 were assessed for micromotion using roentgen stereophotogrammetric analysis (RSA) over a period of 13 years. The fixation of the prostheses remained clinically sound in all cases, although revision had been required for other reasons in seven. In a second group taken from all cases with RSA available on our full database to 1990, 15 tibial components had been followed by RSA from the insertion until, 1 to 11 years after the initial arthroplasty, they were revised for mechanical loosening of the tibial component; 12 of these comprised all the loosenings in the base group, thus making a total of 155 consecutive cases, while an additional three were inserted after the base material had been compiled. The mean migration in the first group was about 1 mm at one year, but subsequent migration was slower, reaching a mean of about 1.5 mm after ten years. About one-third migrated continuously throughout follow-up, while two-thirds ceased to migrate after one to two years. In the revision group, 14 components had migrated continuously and at one year significantly more than those in the first group. One revision case lacked the crucial one-year follow-up and could not be classified. These findings suggest that mechanical loosening begins early in the postoperative period. Clinical symptoms which necessitate revision, seen at this stage in 20% of abnormally migrating tibial components, may not appear until up to ten years after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

We studied the effect of a layer of cement placed under the tibial component of Freeman-Samuelson total knee prostheses with a metal back and an 80 mm intramedullary stem, using roentgen stereophotogrammetry to measure the migration of the tibial component during one year in 13 uncemented and 16 cemented knees. The addition of cement produced a significant reduction in migration at one year, from a mean of 1.5 mm to one of 0.5 mm (p less than 0.01), including a significant reduction in pure subsidence. One year postoperatively the clinical results were similar between the groups, but, at three years, one uncemented knee had required revision.

We studied the effect of a metal tray with an intramedullary stem on the micromotion of the tibial component in total knee arthroplasty. Of 32 uncemented Freeman-Samuelson knee arthroplasties performed in London and Gothenburg, nine had a metal backing and stem added to the tibial component. Micromotion of the tibial components, expressed as migration and inducible displacement, was analysed using roentgen stereophotogrammetric analysis up to two years follow-up. The addition of a metal back and a 110 mm stem to the standard polyethylene component significantly reduced both migration over two years and inducible displacement.

A control system for a multifunctional hand prosthesis, which requires a minimum of training for the amputee, has been developed. The great advantage of the pattern recognition technique in making it possible to control as many as six prosthetic movements has prompted this study. The development of a complete miniaturised system has allowed a clinical trial on four patients. Two different tests have been employed to evaluate this system: an objective computer test and a test representing activities of daily living (ADL test). The computer test shows that a high rate of correct recognition is obtained immediately after the prosthesis is applied to the amputee. The ADL test shows that forearm rotation, and flexion and extension of the wrist are used in most activities, indicating that few compensatory movements are performed. It is suggested that this control system is feasible and that long periods of training are unnecessary.

1. Experience with a refined type of implantable electrode for the myo-electric control of externally powered prostheses is reported.

2. The electrodes are externally energised by electromagnetic induction and therefore do not contain any battery cells. The myo-potentials are transmitted in frequency-modulated form and detected by a receiver placed on the skin. The implantable electrode, measuring 5x11x4 millimetres, is encapsulated in epoxy resin.

3. Six electrodes have been implanted in the forearms of two normal subjects and two below-elbow amputees. The time of implantation ranged from three to fifteen months. Macroscopically, a fibrous capsule developed around the electrodes. Histological examination showed a capsule of granulation tissue of varying thickness with slight inflammatory reaction and foreign-body giant cells.

4. In all cases except one the signals received have been of high quality as ascertained by conventional electromyography and frequency analysis. There has been no significant deterioration in signal quality during the follow-up periods.

5. The major source of failure was fatigue fracture of the gold wires making contact with the body tissues. In one case, however, the electrode was still functioning normally at the time of removal fifteen months after insertion.

6. The patients have not been inconvenienced either by the operative procedures or by the presence of the electrodes in the tissues.