Magnetic resonance imaging of the normal and injured lateral collateral ligaments of the ankle.

BACKGROUND AND AIMS: To study the role of MR Imaging in evaluating both normal and injured lateral collateral ligaments of the ankle. MATERIALS AND METHODS: Twenty-four patients with clinically diagnosed inversion injury to the ankle and 20 healthy volunteers underwent Magnetic Resonance Imaging (MRI) of the ankle with special emphasis on the lateral complex ligaments. RESULTS: The anterior talofibular (ATFL) and posterior talofibular ligaments (PTFL) were identified in 100% of the ankles of normal volunteers in the axial plane. The PTFL was identified in 100% in the coronal plane. The calcaneofibular ligament (CFL) was identified in 76% of the ankles in the axial, 84% in the coronal and 88% in the sagittal plane. Of the 24 patients with inversion injury, MRI showed ligament abnormalities in 16 patients, ten of these were isolated ATFL tears, five had combined ATFL and CFL tears and one case showed in addition abnormal signal in the PTFL. MRI revealed associated injuries to other ligaments and other soft tissue and osseous structures of the ankle in twelve patients. CONCLUSION: MRI is a non-invasive, accurate technique for evaluation of the normal and injured lateral collateral ligaments of the ankle.

Holding power of metallic plates in cancellous bone. An experimental study on rabbits with polymethyl methacrylate as supporting material.

The holding power of a metallic device in cancellous bone was tested in sixteen rabbits (n = 16). The device was fixed with the support of polymethyl methacrylate. The fixation firmness was studied radiologically and by measuring the bonding strength. The mean value of the bonding strength was 485 N (n = 6) at 6 weeks, and 557 N (n = 8) at 12 weeks.

Compartment syndrome of the lower limb caused by a tourniquet: a report of two cases.

Two patients sustained a severe compartment syndrome of the lower limb after surgery under bloodless field for 1 h 25 min and 43 min and with a tourniquet pressure of 350 and 450 mm Hg, respectively. In both cases fasciotomies were performed as an emergency procedure shortly after the initial operation. Renal failure was avoided but functional deficiencies, peroneal weakness, and restricted movements of the ankle resulted in both cases. We conclude that when using a tourniquet, any pre- and postoperative swelling or stiffness of the muscles in the operation area should be noted, even if the recommended time or pressure limits are not exceeded. Immediate fasciotomies of the affected compartments should be considered if the diagnosis is suspected.

Holding power of metallic screws in cancellous bone and metallic plates in cortical bone. An experimental study on rabbits using polymethylmethacrylate and bone graft as supporting material.

The holding power of metallic screws in cancellous bone and metallic plates in cortical bone was tested in sixty rabbits (n = 60). These metallic devices were fixed either without support or with the support of plastic material or autogenous bone graft. The fixation firmness was studied radiographically and by a test of the bonding strength. After six weeks, the mean value of the holding power of screws in cancellous bone without support was 440 N, and that of screws supported by polymethylmethacrylate 674 N and by bone graft 540 N. Corresponding values after twelve weeks were 436 N, 664 N, and 616 N. Fixation with polymethylmethacrylate was better than either fixation without support (P < 0.001, t-test) or fixation with bone graft (P < 0.01), whereas fixation with bone graft was better than fixation without support (P < 0.07). The best fixation was achieved by polymethylmethacrylate according to group mean values. Our investigation of the holding power of plates in cortical bone did not reveal any statistically significant differences between the methods used.

Fixation of osteotomies of the lateral femoral condyle and tibial cortical bone grafts with the aid of plastic material on the rat.

Plastic is used in addition to metallic osteosynthesis in fracture treatment. The object of the present study was to test the usefulness of plastic as the sole fixation material in experimental osteotomies of cancellous bone and in tibial cortical bone grafts. A total of 32 rats were used. In the first group, consisting of 12 rats, the lateral condyle of the right femur was detached and refixed with Silar. In the second group, a tibial cortical bone graft was detached and refixed with Silar in 12 rats and left unfixed in eight. In the first group fixation of the condyle was successful in all cases but one, but in the second group sufficiently stable fixation of the cortical bone graft was not attained and fractures occurred in half the cases.

Bonding strength of alkyl-2-cyanoacrylates to bone in vitro.

This study measured the bonding strength between alkyl-2-cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6-11.2 N/mm2). In long-term experiments under water, n- and i-butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long-term strength.

Experimental osteotomy fixed with composite resins.

In connection with osteosynthesis carried out on the tibias of rats we compared acrylic and bis-GMA plastics (CMW and Silar) and acrylic emulsion and acrylic dispersion used as intermediary material. A total of 80 rats of both sexes were used. The rats were divided into four groups, in which different intermediary material combinations were tested. The observation times were 1, 3, 6, 12, and 24 weeks. Macroscopical, radiological, histological, oxytetracycline fluorescence, and scanning electron-microscopical studies were done. Histologically, the Silar proved to be the more reliable fixation material and acrylic dispersion the better intermediary material. Furthermore, the radiological results were better (P less than 0.05) when acrylic dispersion was used as the intermediary material and Silar as the plastic.

Proximal osteotomy of the tibia in the treatment of osteoarthritis of the knee.

A total of 50 patients with osteoarthritis of the knee joint treated by proximal osteotomy of the tibia were followed up 1-5 years after operation. Fusion occurred within an average of 24 weeks. The subjective result of the treatment was good or fair in 44/50 patients. The results were the same 1-2 years and 4-5 years postoperatively. Half the patients showed some significant general disease, most usually hypertension or cardiac disease. Although the patients' subjective condition was significantly better after than before operation, the treatment did not improve or maintain their working capacity. Preoperatively 29 patients worked, while this number was reduced to 12 at the time of follow-up, and two of the latter patients had been trained for new occupation.

Posterior fusion of the lumbosacral spine. Evaluation of the operative results and the factors influencing them.

The operative results of 79 patients subjected to posterior fusion of the lumbosacral spine were evaluated on the basis of a follow-up examination performed on average 5.4 years after operation. A method of evaluation was developed which measured the patients' subjective improvement and working capacity. The method proved appropriate for clinical use and gave a more correct picture of the operative result than methods relying on the patients' own opinion or the radiographic assessment as the only criterion. Sixty per cent of the patients were subjectively improved, 40 per cent had returned to their previous or a corresponding occupation and 24 per cent had a good operative result, assessed by the method applied. A statistical analysis was performed in order to find the factors influencing the operative results. Age over 40 years, heavy or moderately heavy preoperative work and over 6 months' preoperative disability had a statistically significant, unfavourable effect on the results. In the case of labourers in heavy occupations, working capacity was seldom restored to a degree sufficient for return to their previous work. The operative technique proved reliable with 91 per cent successful fusions, assessed from functional radiographs. Successful fusion did not imply a good operative result, although it did so more often than non-fusion. On the basis of this study, operative fusion of the lumbosacral spine seems to be of relatively little value in the treatment of patients suffering from low back pain, and factors other than purely medical or surgical have a considerable influence on the operative results.