Biomedical subjects
U Jonsson
Publications and source records attributed to U Jonsson.
[The man behind the Bankart injury. He introduced a new technique for shoulder joint dislocation].
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Decrease in vertebral bone density after hip arthroplasty. A quantitative computed tomography study in 18 arthrosis cases.
We investigated the bone mineral density (BMD) of the lumbar vertebrae L1-3 with quantitative computed tomography (QCT) in 18 patients who had been operated on with hip arthroplasty because of unilateral arthrosis. In an earlier prospective study, we did not find any bone mineral changes in the femur or tibia after hip arthroplasty in spite of a large increase of the thigh muscle mass as a sign of a remobilization after the operation. The median BMD had decreased 5.3-8.4 percent in all the measured vertebrae after 6 months postoperatively. Because of the patients' improved walking ability after the operation, this decrease in cancellous vertebral BMD is interpreted as a sign of a post-traumatic osteopenia.
Computer-assisted prediction of the instability of Colles' fractures.
Many Colles' fractures are unstable and have a tendency to redisplace when immobilised in plaster. In an earlier study, we found a high correlation between several parameters from the initial radiographs in 267 patients and the anatomical end results. The predictive power of a new computer programme designed from the data of these patients was investigated in a further group of 107 Colles' fractures. Prediction of the final radiological position was good, especially in the least and moderately displaced fractures. We have found that the initial radial shortening, the type of fracture according to Lidström's classification, and the age of the patients have the greatest value in predicting whether a Colles' fracture will displace to an unacceptable degree.
No effects of piroxicam on osteopenia and recovery after Colles' fracture. A randomized, double-blind, placebo-controlled, prospective trial.
In a randomized double-blind study involving 42 postmenopausal women with a displaced Colles' fracture, we investigated whether piroxicam, a nonsteroid anti-inflammatory drug, can reduce posttraumatic osteopenia and improve the rate of recovery. In an earlier study [3] we found a bone-sparing effect caused by piroxicam after external fixation of the rabbit hindleg. The patients were treated with a below-elbow paster slab for 4 weeks after the reduction. The bone mineral content of the forearm bones was measured with a single-photon absorptiometer 8 weeks after the fracture. There was a mean 7% bone mineral decrease in the radius and 5% in the ulna among the patients treated with piroxicam versus 10% in the radius and 7% in the ulna in the placebo group. However, this difference was not significant. Piroxicam did not decrease the rate of fracture healing. The patients who received piroxicam had significantly less pain during plaster treatment, but there was no difference in the rate of functional recovery between the groups.
A new rat model of arterial thrombosis with a platelet-rich head and an erythrocyte-rich tail: thrombolysis experiments with specific thrombin inhibition.
A model for thrombolysis in rats was developed. Repeated, focal external heating was applied to the carotid artery which leads to the development of a cyclic blood flow with slow, steady decreases followed by abrupt increases. When this cyclic blood flow stops spontaneously, the entire arterial segment (approximately 10 mm) can be demarcated with snares to create an arterial thrombus of fixed size, with a platelet-rich head and an erythrocyte-rich tail. The usefulness of the model was tested by evaluating the thrombolysis induced by a low dose of recombinant tissue-type plasminogen activator (rt-PA) alone and rt-PA in combination with standard heparin and recombinant hirudin. Re-canalization of the artery was measured as blood flow and as the residual 125I-radioactivity in the artery at the end of the experiment, resulting from 125I-fibrinogen incorporated during the formation of the thrombus. Both blood flow and 125I-activity measurements show that hirudin, but not heparin in combination with rt-PA, significantly improves thrombolysis, which is in accordance with previous experimental findings. It is concluded that the model, with a thrombus resembling the thrombus found in man after coronary occlusion, enables complicated experiments with thrombolysis frequently performed only in large animals to be performed in rats.
Bone and muscle mass after hip rearthroplasty. Controlled CT study of 12 patients.
The cortical bone mineral density (BMD), bone volume, bone mass and muscle volume of the thigh and the cancellous BMD of the distal femur and proximal tibia were quantified by computed tomography (QCT) in 12 patients after hip rearthroplasty due to prosthetic loosening following arthroplasty for arthrosis. Both legs were scanned and the operated side was compared with the healthy side. A control group, 12 patients, had had unilateral hip arthroplasty without subsequent rearthroplasty. There was a 19 percent decrease in bone mass and 13 percent decrease in muscle volume in the middle femur, compared to the contralateral side, in the patients who had undergone rearthroplasty, and a reduction of 9 percent for the same variables in the control group. There was also a more marked osteopenia in the reoperated extremity in the distal femur and proximal tibia compared to the unoperated side.
Cruciate ligament prosthesis vs. augmentation. A randomized, prospective 5-year follow-up of 41 cases.
In a prospective study, 18 patients were randomized to a prosthesis and 23 patients to the Kennedy Ligament Augmentation Device (LAD) because of functional instability due to old anterior cruciate ligament injuries. The operations were performed with use of a modified over-the-top technique. At the last follow-up (5 years), postoperative improvements in scores were maintained for both groups, but LAD-reconstructed patients had better Lysholm and activity scores than the Goretex group. The achieved postoperative improvement in anterior stability (KT-1000) did not deteriorate for either of the groups during the 5-year follow-up. The Goretex patients had more effusion and pain and more secondary operations.
Bone and muscle mass after hip arthroplasty. A quantitative computed tomography study in 20 arthrosis cases.
We performed a prospective, quantitative computed tomography (QCT) study of bone mineral density (BMD), cortical bone volume, bone mass and muscle volume in 20 patients who were operated on with cemented total hip arthroplasty because of unilateral arthrosis. Both extremities were measured preoperatively, 3 and 6 months after the operation by a single-energy computer tomograph equipped for bone mineral densitometry. Preoperatively, we found a 25 percent decrease in muscle volume of the thigh on the arthrosis side compared to the contralateral side, but only a 6 percent decrease in bone mass, mainly of the cortical bone volume in the middle femur. In the cancellous bone of distal femur and proximal tibia there was a reduction in BMD of 11 and 14 percent, respectively, compared to the contralateral side. After 6 months, we found no changes in cortical bone mass, either on the operated femur or on the contralateral, control femur. The BMD of cancellous bone in distal femur and proximal tibia had not changed. However, the thigh muscle on the operated side showed a strong recovery; 6 months after the operation there was a 19 percent gain on the operated side.
[Colles' fracture and patient insurance: inform early about the risk of redislocation].
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[Periodontal health care--a data-based index system].
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Piroxicam-induced reduction in osteopenia after external fixation of rabbit tibia.
Twelve rabbits were treated with a unilateral external fixator in one tibia for 12 weeks, while the other tibia served as an intact control. Half of the animals were also treated with 10 mg/kg/day of piroxicam, given in two daily oral doses. Changes in bone mineral content were determined using single photon absorptiometry. After 12 weeks, we found a 3 percent decrease in the bone mineral content in the tibia of the animals treated with piroxicam versus 9 percent in the nonpiroxicam group (P = 0.04). In the femurs, there was an insignificant decrease in bone mineral, 2 percent (piroxicam) and 1 percent (nonpiroxicam) respectively. The results indicate that piroxicam may reduce the osteopenia caused by external fixation.
Bone mineral loss after Colles' fracture. Plaster case and external fixation equivalent.
The bone mineral content of the radius and ulna was analyzed in 31 postmenopausal women with displaced Colles' fractures. Sixteen fractures were treated with a below-the-elbow plaster case and 15 with primary external fixation. The bone mineral content of the forearm bones was measured with a photon absorptiometer 9 (6-24) months later. There was a mean 15 percent mineral decrease in the radius, but no difference between the two treatment groups. The decrease did not correlate with the age of the patient, nor was there any correlation with grip strength or range of wrist motion. The more severe fractures, according to the Frykman classification, had a more pronounced mineral loss than the simpler fractures.
Goretex prosthetic ligament vs. Kennedy ligament augmentation device in anterior cruciate ligament reconstruction. A prospective randomized 3-year follow-up of 41 cases.
In a prospective randomized study on patients with functional instability due to old anterior cruciate ligament tears, 18 were randomized to a Goretex reconstruction and 23 to augmentation with the Kennedy Ligament Augmentation Device (LAD). All operations were performed with use of a modified over-the-top technique. At follow-up (median 36 months), improvements in Lysholm scores, activity scores, and arthrometry values were recorded in both groups as compared with preoperative levels. The LAD group had better Lysholm scores than the Goretex group. Among Goretex-reconstructed knees, effusion and pain occurred, and major effusions in two knees caused by the Goretex artificial ligament were indications for graft explant after 4 years. Our short-term results with the Goretex prosthetic ligament are not acceptable because of effusions and of pain. Our short-term results of the LAD polypropylene braid as an augmentation to an autologous graft seem promising.
Stress protection by external fixation of the rabbit tibia.
Osteopenia of the tibia and femur caused by an external fixator in the tibia was studied in 14 rabbits. Eight rabbits were treated with a complete unilateral external fixator in one tibia, whereas the other tibia served as control. The other 6 animals had one leg operated on with inserting of all the pins but without the frame. This technique was chosen to compare osteopenia caused by stress protection and the effect of the pins. After 6 weeks, we found a 7 percent reduction in the bone mineral content in the tibial diaphyseal segment between the pins of the external fixator and no bone loss in the tibia that were operated on with only pins. In the femurs, there was a smaller decrease in the bone mineral content: respectively 3.2 percent (complete frame) and 2.9 percent (only pins). On all the operated on tibiae, there was an increase in the bone mineral content around the pins both proximally and distally.
Regional anesthesia preferable for Colles' fracture. Controlled comparison with local anesthesia.
In a prospective randomized study of 99 displaced Colles' fractures, regional intravenous block was compared with local anesthesia in the fracture hematoma. Patients treated with regional intravenous block had less pain during the manipulation of the fracture and better grip strength at the 6-month follow-up. The anatomic end result (dorsal angulation) was better after regional anesthesia.
External fixation or plaster cast for severely displaced Colles' fractures? Prospective 1-year study of 46 patients.
In a prospective randomized study of 47 severely displaced Colles' fractures, 23 had external fixation and 24 had a dorsal plaster cast. Five fractures in the plaster-cast group redislocated and were externally fixed at rereduction after the 11-day follow-up. Three patients in the external-fixation group had a noncomplicated pin-tract infection, and 1 patient had a transient sensory disturbance arising from the cutaneous branch of the superficial radial nerve. After 1 year, the patients allocated to primary external fixation had a better radiographic and functional end result; according to Lidström's grading, 19/22 were excellent or good after external fixation as compared with 12/19 after plaster-cast treatment.