Norvald Langeland

Antibiotic prophylaxis in total hip arthroplasty

We have assessed the effect of different regimes of antibiotic prophylaxis on the survival of total hip implants, comparing antibiotics administered both systemically and in the bone cement, systemically only, in the bone cement only and with no antibiotics given. We studied 10 905 primary cemented total hip replacements, performed for osteoarthritis of the hip and reported to the Norwegian arthroplasty register between 1987 and 1995. Cox-estimated failure-rate ratios (FRR) are presented with adjustment for gender, age, the brand of cement, the prosthesis, the type of operating theatre and the operating time. For revisions performed for infection (39 operations), the lowest rate of revision was found among patients receiving antibiotic-containing cement plus systemic antibiotics (n = 5804). The revision rate for the 4586 patients receiving systemic antibiotics only was 4.3 times greater (95% CI 1.7 to 11.0, p = 0.001); in 239 with antibiotics in the bone cement only it was 6.3 times greater (CI 1.6 to 25.0, p = 0.003); and in the 276 who did not receive antibiotics it was by 11.5 times greater (CI 2.1 to 63.0, p = 0.002). Adjustment for the total amount of systemic antibiotic administered did not change the results. We also observed an increased revision rate for aseptic loosening (109 operations) comparing the systemic-only (FRR = 1.8, CI 1.1 to 2.9, p = 0.01) and the cement-only regimes (FRR = 2.6, CI 1.2 to 5.9, p = 0.02) with the combined dosage. Our findings show that systemic antibiotics combined with antibiotic-containing bone cement led to fewer revisions than the other methods.

Methods for Testing the Mechanical Properties of the Rat Femur

A modular apparatus to measure the bending and torsional properties of the rat femur is presented. Both intact femur diaphyses and diaphyseal fractures in different phases of healing can be tested. It is also possible to measure the bending-strength of the distal femur metaphysis and the epiphyseal plate. The apparatus can be used to investigate the effect of drugs and hormones on the remodelling of the rat femur.

Patient satisfaction and function after primary and revision total hip replacement.

This study assessed and compared satisfaction and function before and after total hip replacement as reported by 531 patients who had primary and revision surgery and 1087 patients who had primary surgery only. All operations were registered by the Norwegian Arthroplasty Register during the years 1987 to 1993, with time from last surgery to followup ranging from 0.6 to 6.4 years. Sixty-one percent of the patients who underwent revision surgery and 84% of the patients who did not undergo revision surgery rated their overall satisfaction with the hip implant as good or very good. With adjustment for primary diagnosis, gender, age, bilaterality, and time since the primary operation, a substantial benefit of total hip replacement was observed in both groups with regard to pain, walking ability, and need of help. However, improvement was less among patients who underwent revision total hip replacement than among those who did not undergo revision surgery. A deterioration was seen among patients who underwent revision surgery with regard to employment status and exercise habits.

The Norwegian arthroplasty register: A survey of 17,444 hip replacements 1987–1990

In Norway a national register for total hip replacements was established in September 1987. Up till February 1991, 17,444 total hip replacements (THR) were reported, i.e., 140 THR/100,000 inhabitants/year. The median age of the patients was 70 years, and 69 percent were women. 87 percent were primary arthroplasties and 13 percent were revisions. Primary arthrosis was the diagnosis in 68 percent of the primary operations. The acetabular implants were uncemented in 17 percent and the femoral implants in 12 percent of primary operations. In revisions, the implants were uncemented in 21 and 17 percent, respectively. The reasons for revision were loosening of components in 87 percent and deep infection in 4 percent. The Charnley prosthesis dominated with 49 percent of all implants. A total of 422 different designs and sizes of acetabular implants, 398 femoral implants and 166 of caput designs and sizes were used. This large number of different types and designs seems unreasonable.

Patient-related risk factors for early revision of total hip replacements. A population register-based case-control study of 674 revised hips.

In this population register-based, matched case-control study, we assessed patient-related factors and early risk of revision after total hip replacement (THR). Information was obtained via a mall survey among patients reported to the Norwegian Arthroplasty Register during the period 1987-1993. The study included 674 revised hips, as cases, and 1,343 hips with a primary operation only, as controls. Completed questionnaires were received from 81% of the 2,017 individual cases and controls. We identified a set of patient-related factors associated with poor THR prognosis. Increasing weight was a risk factor among male patients older than 67 years who were more than 1.77 m tall (p = 0.01). Smoking had no overall effect, but former heavy smokers had an increased risk of 2.8 compared to never-smokers. Alcohol intake was associated with an increased risk of dislocation. Revision due to infection was commoner among patients taking anti-diabetic drugs (OR = 14) than among patients taking no medication. An increased overall revision risk was found among patients using systemic steroids (OR = 2.8) or local pulmonary steroids (OR = 6.0). The risk also increased in male patients performing regular exercise before the primary operation (OR = 2.6), and in female patients of working-age doing heavy work (OR = 1.9).

Bone changes after castration in rats. A model for osteoporosis

Bone changes 6-12 weeks after castration have been studied in 25 female and 27 male middle-aged rats. Castrated female rats gained more weight than their controls, but had decreased bone density and calcium and hydroxyproline content per cm3 bone volume of tibia. Castrated male rats did not differ from controls regarding body weight and the bone parameters. No influence of castration on the mechanical strength of the femora could be detected in either sex. At 2 weeks after castration, the circulating levels of immunoreactive calcitonin (iCT) were decreased in female rats compared to controls. In contrast, iCT was increased both in castrated male and female rats 10 weeks later. We conclude that castration of 6-month-old female rats causes osteoporosis, and therefore represents a promising experimental model for studying postmenopausal bone loss.

ANTIBIOTIC PROPHYLAXIS IN TOTAL HIP ARTHROPLASTY

We have assessed the effect of different regimes of antibiotic prophylaxis on the survival of total hip implants, comparing antibiotics administered both systemically and in the bone cement, systemically only, in the bone cement only and with no antibiotics given. We studied 10,905 primary cemented total hip replacements, performed for osteoarthritis of the hip and reported to the Norwegian arthroplasty register between 1987 and 1995. Cox-estimated failure-rate ratios (FRR) are presented with adjustment for gender, age, the brand of cement, the prosthesis, the type of operating theatre and the operating time. For revisions performed for infection (39 operations), the lowest rate of revision was found among patients receiving antibiotic-containing cement plus systemic antibiotics (n = 5804). The revision rate for the 4586 patients receiving systemic antibiotics only was 4.3 times greater (95% CI 1.7 to 11.0, p = 0.001); in 239 with antibiotics in the bone cement only it was 6.3 times greater (CI 1.6 to 25.0, p = 0.003); and in the 276 who did not receive antibiotics it was by 11.5 times greater (CI 2.1 to 63.0, p = 0.002). Adjustment for the total amount of systemic antibiotic administered did not change the results. We also observed an increased revision rate for aseptic loosening (109 operations) comparing the systemic-only (FRR = 1.8, CI 1.1 to 2.9, p = 0.01) and the cement-only regimes (FRR = 2.6, CI 1.2 to 5.9, p = 0.02) with the combined dosage. Our findings show that systemic antibiotics combined with antibiotic-containing bone cement led to fewer revisions than the other methods.

Early revision among 12,179 hip prostheses: A comparison of 10 different brands reported to the Norwegian Arthroplasty Register, 1987-1993

On the basis of data from the Norwegian Arthroplasty Register during the period 1987-1993, we have compared times to revision for 10 different cemented total hip prostheses. A total of 11,169 patients, with 12,179 primary total hip replacements (THRs), performed with high viscosity cement for primary arthrosis and followed for a maximum of 6.4 years, were included in this study. The Kaplan-Meier estimate of the overall percentage revised after 5 years was 2.5 (95% Confidence Interval: 2.1-3.0). For the Charnley prosthesis (n 6,694), 2.9% were revised after 5 years (95% CI: 2.3-3.4). Using Cox regression to adjust for gender, age, type of cement and use of systemic antibiotic prophylaxis, the Charnley prosthesis was compared with the 9 other brands. The revision rate for the Spectron/ITH combination (Spectron acetabulum, ITH femur) (n 1,034) was only 0.35 (p 0.04) times that of the Charnley prostheses. The Elite/Charnley combination (Elite acetabulum, Charnley femur) (n 507) and the Müller Type prosthesis (n 116) showed poorer results with failure rates 2.3 (p 0.01) and 2.7 times (p 0.04) that of Charnley, respectively. Although the overall results for cemented THRs in general were good, clinically important differences in revision rates were demonstrated among the cemented prosthesis brands. Our findings underline the need for careful evaluation of different total hip replacements.

Age-dependent mechanical properties of rat femur : measured in vivo and in vitro

Strain gauges were implanted on the anterior surface of the femoral diaphysis of rats aged 6, 12 or 52 weeks. Strain was recorded while the rats were running on a treadmill. The peak strain was of the same magnitude at different animal ages, although there was a somewhat lower value for 52-week-old animals. Stiffness calculated from in vivo strain measurements and from a 3-point bending test on excised femora was correlated: stiffness increased with age. Maximum bending stress increased from 6-12 weeks of age, but then there was no further increase. Ultimate load, on the contrary, increased steadily over the entire 52-week period. This indicates that higher load-bearing capacity with increased age in adult rats is due to increased dimensions of the bone rather than its material properties. The present study demonstrates that conventional in vitro measurements of mechanical properties of bone correspond to measurements of strain during physical activity, and that both are valid measurements of physical properties of bone.

Effects of a distal venting hole in the femur during total hip replacement

SummaryIn 18 patients who underwent total hip replacement, the intramedullary pressure in the femur was measured during the insertion of the femoral prosthesis component. Half the patients had a pressure release hole (diameter 4.5 mm) drilled into the medullary canal at the distal end of the femur, the other half not. In the patients without a venting hole, the intramedullary pressure increased transiently to a median of 390mm Hg during the insertion of the femoral stem, while those with a venting hole only showed an increase to 23 mm Hg. A drop in arterial oxygen tension of 2.2kPa and in thrombocytes of 51 × 109/1 was found in those without a venting hole, while the corresponding values in those with a venting hole were 0.9kPa and 20 × 109/1. Furthermore, a significant correlation was demonstrated between the increase in intramedullary pressure and the drop in oxygen tension and in blood platelets. No significant change in blood pressure was measured during operation in either group.ZusammenfassungBei 18 Patienten, die einen totalen Hüftgelenkersatz erhielten, wurde der intramedulläre Druck im Femur während des Einsetzens der femoralen Prothesenkomponente gemessen. Bei der Hälfte der Patienten war im distalen Femur ein Druckentlastungsloch von 4,5 mm Durchmesser gebohrt worden. Beim Einsetzen des Prothesenschaftes kam es bei den Patienten ohne Entlastungsloch zu einem vorübergehenden Anstieg des intramedullären Druckes bis zu einem Medianwert von 390mmHg, während mit dem Entlastungsloch die Drucksteigerung nur 23mmHg betrug. Ohne Entlastungsloch wurde ein Absinken des arteriellen Sauerstoff-Partialdrucks von 2,2kPa and der Thrombocyten von 51 × 109/1gefunden,miteinemEntlastungsloch betrugen these Werte 0,9kPa bzw. 20 × 109/1. Ferner wurde eine signifikante Korrelation zwischen der Steigerung des intramedullaren Drucks and dem Abfall des Sauerstoff-Partialdruckes and der Thrombocytenzahl gezeigt. Eine signifikante Veränderung des Blutdrucks während der Operation wurde bei keiner der beiden Gruppen gemessen.