Jørgen Steen Jensen

Unstable trochanteric fractures : a comparative analysis of four methods of internal fixation

A series of 1,071 patients with unstable trochanteric fractures were treated by the McLaughlin or Jewett nail-plate, the sliding screw-plate or condylocephalic nailing according to Ender. Deep infection was encountered in 2.5% of the cases following surgery in the hip region and in 3.3% of the Ender nailings. Statistical analyses showed that the quality of the reduction was determined by the comminution of the fracture, and the technical failure of fixation or secondary displacement of the fracture was determined by the quality of the reduction. Sliding screw-plate fixation was found to be the only suitable fixation method for unstable trochanteric fractures, because of a low failure rate, a low re-operation rate and the possibility of secondary impaction without disturbing the fracture union.

Determining factors for the mortality following hip fractures

In this study 518 patients with hip fractures were followed up prospectively for an average of 3 years (range 2.5-3.5 years). On admission to hospital the patients were allocated to one of 4 social function groups according to their dependence on the social welfare system. The life expectancy was analysed at follow-up and found to be determined primarily by the patients social dependence prior to fracture, and secondarily by the age of the patient. Other generally accepted determining factors were not found to have any significant influence on the survival rates.

Femoral shaft fracture after hip arthroplasty

Femoral shaft fractures after hip arthroplasties were treated in 74 noncemented hemiarthroplasties and 65 cemented arthroplasties. In loose prostheses the best clinical results and the least number of operations were achieved with revision arthroplasty with a long-stem prosthesis, combined with simple internal fixation methods when applicable. In firmly fixed prostheses the results of revision arthroplasty and traction treatment were similar. Cemented revision arthroplasty did not interfere with fracture union. Internal fixation with the prosthesis in situ cannot be recommended because of a large number of secondary revision arthroplasties and nonunions. Removal of the femoral stem prosthesis and internal fixation nearly always require a secondary revision and cannot be recommended.

Evaluation of instruments for measuring grip strength

Three instruments for measuring grip strength: the steel spring dynamometer, the Martin Vigorimeter and the My-Gripper, were tested in a universal testing machine to evaluate the linearity of the readings. Furthermore, a clinical study including 100 normal probands evaluated the applicability of these instruments. It was concluded that the steel spring dynamometer was not suitable for clinical use, due to its lack of precision. The Martin Vigorimeter and the My-Gripper were both very precise instruments. The My-Gripper seems to be preferable for clinical use because it is cheap and easy to handle. Also, the instrument can accumulate the results of several trials, facilitating the calculation of average grip strength. A nomogram showing the relationship between the dominant and the non-dominant hand is given.

Unsatisfactory results after repeated revision of hip arthroplasty : 61 cases followed for 5(1-10) years

61 cemented second revision total hip arthroplasties and 18 cemented third revision total hip arthroplasties were studied with emphasis on causes of failure, complications, risk of further revision, and clinical and radiographic results of surviving, not further revised patients. Aseptic loosening was the major reason for both second and third revisions followed by recurrent dislocations. Of 61 second revisions, 21 failed again. Postoperative dislocation was the major complication, encountered in 10/61 after second revisions and in 4/18 third revisions. 10 second revisions were reoperated on without exchange of components, but for causes related to the implant. The clinical and radiographic outcome of surviving, not further revised patients was favorable, but must be seen in the light of the high rate of further revisions. In 33 of 53 second revisions and in 5 of 13 third revisions left for evaluation, the outcome was considered unsatisfactory. We conclude that reoperations for failed arthroplasties should be the prerogative of highly experienced centers.

Effects of polymerization heat and monomers from acrylic cement on canine bone

We investigated the effects of polymerization heat and toxicity of polymethylmetacrylate bone cement in the canine tibial diaphysis. Heat was studied by filling the tibias with either bone cement or bone wax contained in a monomer tight membrane pouch. Toxicity was studied by filling both tibias with cement, with the control side contained in the membrane pouch. Bone blood perfusion was measured by microsphere technic, and bone remodeling by 99mTc-methylene diphosphonate uptake and by histologic technique. In bone exposed to the combination of polymerization heat and monomer, both perfusion and remodeling were impaired. We did not find any effects of polymerization heat alone. We conclude that hot toxic chemicals from bone cement during polymerization may inhibit bone blood perfusion and remodeling, whereas heat alone seems to be of minor importance for the regenerative processes in cemented diaphyseal bone.

Mixing does not improve mechanical properties of all bone cements. Manual and centrifugation-vacuum mixing compared for 10 cement brands.

Contemporary mixing methods--centrifugation, vacuum mixing with or without precompression--were compared with manual mixing by testing strength characteristics in accordance with a proposed revision of the international standard for bone cements as applied to 10 cement brands. Simplex brands and low-viscosity cements were the strongest, and were not improved by any of the vacuum-mixing procedures. Centrifuging was found unsuitable for low-viscosity cements. Without attaining the strength of the former, the cements best suited for auxiliary mixing methods were CMW-1 and Palacos brands, which improved 6-11 percent by either of the methods. The Sterivac system was generally found unacceptable, because about 20 percent of a cement package was retained in the mixing gear, and the application of precompression had no additional effect on compressive and bending strengths.

Prechilling and vacuum mixing not suitable for all bone cements: Handling characteristics and exotherms of bone cements*

Nine bone cements were tested for handling characteristics, intrusion, doughing time, setting time, and exothermic temperature. Comparative studies were made of manual mixing and vacuum mixing of cement components stored at room temperature or chilled to 5 degrees C. Vacuum mixing of cement packages stored at room temperature was inapplicable except for the low-viscosity brands, as the cements became too viscous to mold test specimens. Prechilling and vacuum mixing prolonged the setting time and preserved a lower viscosity during the handling period. Palacos R and Palacos G were most suitable for this method, whereas a considerable increase in exothermic temperature was experienced with the other brands. The method might, however, be considered for Zimmer and Cerafix also, as the exotherm was of the same magnitude as for Palacos brands.

Antibiotic treatment insufficient for established septic arthritis Staphylococcus aureus experiments in rabbits

We treated septic arthritis of the knee in 38 rabbits with cloxacillin i.m. once and twice daily combined with probenecid for 7 or 21 days, respectively, or with only cloxacillin i.m. thrice daily for 7 days. The animals were killed weekly in groups up to 5 weeks after inoculation. Aspirated cultures obtained after 4 days of treatment were always negative. Histologic specimens revealed progressive joint destruction, but at a slower rate after frequent treatment independent of the period. We concluded that antibiotic therapy alone could not prevent destruction of articular cartilage once bacterial arthritis was established.

Arthroplasty for congenital hip dislocation Techniques for acetabular reconstruction

We investigated a series of 63 arthroplasties for chronically dislocated hips or severe dysplasia with at least two thirds of the femoral head uncovered. Direct cementation into the neoacetabulum at the pelvic wing was followed by 6/20 revision arthroplasties and 3/20 impending failures. Cups supported by cortical bone grafts were revised in 8/16 and found loose in 2/12 arthroplasties. The best technique was restoration of the rotational center of the hip joint and roof reconstruction with a femoral head graft with 2/25 revisions and signs of loosening in 2/25.