Jørn Jensen

Socket loosening in arthroplasty for congenital dislocation of the hip

Mechanical risk factors in loosening of the socket were radiographically analyzed in 123 Charnley arthroplasties performed during the period 1969-1982 for coxarthrosis secondary to congenital dislocation. The socket was placed as near the true acetabulum as possible without extensive soft-tissue release and without reinforcement of the acetabular roof by bone grafting. The rate of socket loosening was 19 percent using progression of a radiolucent line at the bone-cement interface to a width of greater than 1 mm as the criterion for loosening. Different predictors of loosening were analyzed by stepwise logistic regression analysis. Lack of lateral bony support for the socket was the prime predictor. The next most important predictors were the preoperative degree of hip dislocation and the position of the socket in relation to the true acetabulum.

SURVIVORSHIP ANALYSIS OF CEMENTED TOTAL CONDYLAR KNEE ARTHROPLASTY: A LONG-TERM FOLLOW-UP REPORT ON 348 CASES

Survivorship analysis was used in the evaluation of 348 consecutive primary total condylar knee arthroplasties (total knee arthroplasties) performed on 253 patients in a 27-month period, with a maximum follow-up period of 12 years. The diagnosis was osteoarthrosis in 184 cases and rheumatoid arthritis in 164 cases. Ten patients (10 total knee arthroplasties) were lost to follow-up evaluation. The endpoint was defined as prosthesis not in situ. The variables considered were age, sex, body mass index, and diagnosis. The overall cumulative survival rate was 92%. The survival rate of the osteoarthrosis group was significantly higher (97%) than that of the rheumatoid arthritis group (87%). None of the other variables affected survival rate significantly.

Cancellous Bone Strength at the Proximal Human Tibia

Machined specimens from ten cadaver proximal tibiae were tested in compression to study the variation of mechanical strength with the distance from the joint surface. There was a statistically significant reduction of stiffness and strength with increasing distance from the joint beneath the lateral condyle and the intercondylar area; at the medial condyle no such reduction could be demonstrated. Linear regression analysis showed that the tangent modulus may be used to predict yield strength (r = 0.92) and ultimate strength (r = 0.91) when destruction of the specimen is undesirable.One important limitation of the technique employed is that the length of test specimens determines the resolution that can be obtained.

Long-term results of total condylar knee arthroplasty in rheumatoid arthritis

We have reviewed at an average period of ten years the results of 71 consecutive primary arthroplasties with the Insall-Burstein total condylar knee prosthesis in patients with rheumatoid arthritis. Their mean age at surgery was 52 years (24 to 72). At follow-up the overall results (Hospital for Special Surgery knee rating score) were excellent or good in 77%, fair in 11% and poor in 11%. There was residual pain in only 5% of patients with prostheses in situ; 58% could walk more than 500 m, and the median range of motion was 108 degrees. Eight knees had been revised. Five underwent arthrodesis because of deep infection and three needed revision arthroplasty for mechanical loosening. The crude survival rate of the arthroplasties was 89%. The presence of radiolucency around the tibial component correlated significantly with the severity of residual pain.

Years of potential life lost after hip fracture among postmenopausal women

From January 1987 and onwards all cases of hip fracture in Arhus County, Denmark, were registered in a prospective multicenter investigation. Until December 1990, 2273 postmenopausal women (greater than 50 years) with first hip fractures were registered. Of these 643 sustained a hip fracture in 1988. Life tables were constructed for different age groups; the excess mortality (in comparison with the reference population) for each age group ranged from 10 to 20 percent. The years of potential life lost (YPLL) (life expectancy method) were calculated for the 1988 cohort and compared with the YPLL due to other selected conditions calculated from official vital statistics. The YPLL rates (per 1000 persons) were as follows: hip fracture 9.2, ischemic heart disease 73, cerebrovascular disease 29, breast cancer 20 and cancer of the uterus 6.7. We propose that hip fracture mortality data should be continuously registered and evaluated using the YPLL method to detect changes caused by the expected increase in the number of hip fractures.

Heterotopic bone formation after total hip arthroplasty in patients with primary or secondary coxarthrosis.

Heterotopic bone formation was investigated in 392 Charnley low-friction total hip arthroplasties. A multivariate linear regression analysis was used to account for the influence of co-variables: sex, age at surgery, postoperative treatment with antiinflammatory drugs during at least the first 2 weeks, and previous ipsilateral hip surgery. A total of 232 hips had been treated for primary coxarthrosis, and 114 and 46 hips for secondary coxarthrosis due to congenital dislocation and fracture-dislocation of the hip, respectively. None of the hips with primary coxarthrosis previously had ipsilateral hip surgery, whereas 41 hips (36%) in patients with congenital dislocation of the hip and 28 hips (61%) in patients with fracture-dislocation of the hip had one or more ipsilateral surgical procedures prior to the arthroplasty. The sex ratio varied between the groups, with a male:female hip ratio of 1:1, 1:10, and 3:1 for the three groups, respectively. The risk of developing grades 2 or 3 heterotopic ossification after total hip arthroplasty were significantly higher in men, patients without postoperative treatment with antiinflammatory drugs, and patients above age 60. In contrast, the analysis documented that previous ipsilateral hip surgery and type of coxarthrosis did not influence lesion development, supporting the theory that a systemic, rather than local factor, is responsible for the development of heterotopic bone formation after total hip arthroplasty.

Dislocated Femoral Neck Fractures: A Follow-up Study of 98 Cases Treated by Multiple AO (ASIF) Cancellous Bone Screws

A series of 98 dislocated femoral neck fractures were treated by closed reduction and osteosynthesis with multiple AO (ASIF) cancellous bone screws. The patients were followed up for 2 years (or until death). The degree of dislocation did not have a statistically significant influence on the failure rate, which was, however, significantly correlated with poor reduction. Thirty-nine percent of the fractures were complicated by non-union or late segmental collapse. Forty-three of the patients participated in the 2 year follow-up examination. Of these patients, 38 had achieved excellent or good hip function. It was concluded that the reduction was the most important single factor in treatment of these factors.

A further study of the kinetics of cholesterol uptake at the endothelial cell surface of the rabbit aorta in vitro

Abstract This study is concerned with a further development of the kinetics of the uptake in vitro of [4- 14 C] cholesterol by intima-media layers of thoracic aortas from normal rabbits. 1. 1. Separation of the intima-media [ 14 C]cholesterol into the free nd esterified forms revealed that the majority of the labelled serum cholesterol, bound initially at the luminal endothelial cell membrane, was in the esterified form. Following the initial binding phase, no significant increase was observed in esterified [ 14 C]cholesterol of the intima-media, whereas the intima-media content of free [ 14 C]cholesterol increased with time at a rate equal to that for the uptake of total [ 14 C]cholesterol in the second phase. A transport of esterified [ 14 C]cholesterol across the endothelial cell surface would thus imply a hydrolysis following uptake. 2. 2. These findings are in agreement with the demonstration that less than 3% of the non-labelled intima-media cholesterol pool of the rabbits is found in the esterified form. 3. 3. Based on the above findings a model is shown for the uptake of cholesterol by intima-media. The mathematical treatment of the model indicates that the previously found relationship between cholesterol transfer rate and concentration of total cholesterol in serum is in agreement with the model. An estimation of the amount of cholesterol, which maximally can be bound per unit surface area, shows this amount to be of the same order of magnitude as the amount of cholesterol found in a lipoid monolayer of the same area. The rate constant for the cholesterol transfer across the endothelial cell surface is about the same order of magnitude as that for the ingestion in rabbit macrophages. 4. 4. The kinetics presented are compatible with morphological descriptions of a pinocytotic uptake process.

Arthroscopy in acute knee injuries

The diagnostic value of arthroscopy was evaluated in 148 patients with acute hemarthrosis and/or instability of the knee. The treatment planned after clinical examination was compared with the treatment given after arthroscopy. Seventy-nine per cent of the patients had ligamentous injuries; 59 per cent of tears were combined with other injuries, and 71 per cent were complete ruptures. Stability testing under anesthesia was most inaccurate for the anterior cruciate ligament, with 13 per cent false positive and 30 per cent false negative results. The planned treatment was altered as a consequence of arthroscopy in 31 per cent of cases. Without arthroscopy, the preoperative diagnoses would have been seriously wrong in 15 per cent of the patients. Twenty per cent of total anterior cruciate ligament ruptures would have been overlooked.

Heterotopic bone formation following hip arthroplasty: A retrospective study of 65 bilateral cases

Heterotopic bone formation after two-stage bilateral cemented total hip arthroplasty was evaluated in 65 patients (23 women and 42 men) who had not received treatment with antiinflammatory drugs in the immediate postoperative weeks. The mean age at the first operation was 65 years, and the median interval between the two arthroplasties was 3 months. Fifty-two patients developed heterotopic ossification after the initial hip arthroplasty. Of these patients, 40 also developed ossifications after contralateral hip arthroplasty. Out of 11 males developing Grade-III heterotopic ossification after the initial hip arthroplasty, 8 also developed Grade-III ossification after contralateral hip arthroplasty. Two females developed Grade-III ossification after the initial arthroplasty, but neither of them developed a Grade-III lesion after contralateral total hip arthroplasty. Males with Grade-III heterotopic ossification after the initial hip arthroplasty were shown to be at a high risk of developing the same severe lesion after contralateral total hip arthroplasty, making them candidates for postoperative prophylaxis.