Biomedical subjects
Publications and source records attributed to N W Pedersen.
The nutritional status was evaluated prospectively in 47 consecutive patients who were amputated for lower extremity ischemia. It was good in 13 patients, reduced in 18, and poor in 16. Malnourished patients had a higher frequency of impaired wound healing, and an increased risk of postoperative cardiopulmonary and septic complications; all 6 deaths occurred in these groups.
In a prospective study, we performed 18 core decompressions for Stage I primary osteonecrosis of the femoral head. Only 5 patients (six hips) seemed to have benefited from the intervention for more than 1 year.
Eleven children with simple bone cysts in the proximal humerus metaphysis were treated with intracavity infiltration of methylprednisolone acetate. Nine patients were treated once; the remainder required second injections. Five lesions resolved completely, while six healed sufficiently to eliminate the risk of pathologic fracture, and to permit physical activities without restrictions. Simple bone cysts can be treated satisfactorily with injection of methylprednisolone acetate, thus obviating surgery.
We studied the safety of combining the postoperative use of a non-steroidal anti-inflammatory drug with low-dose heparin. In a double-blind, placebo-controlled clinical trial we reviewed the complications in 235 patients after total hip replacement, all treated with low-dose heparin and either indomethacin or a placebo. The incidence and type of complications in the two groups were nearly equal; indomethacin-treated patients had no increase in complications related to bleeding. Postoperative bleeding into drains was marginally greater in the indomethacin group, although the difference was not statistically significant. We conclude that treatment with indomethacin and low-dose heparin after hip replacement does not significantly increase the bleeding or other complications. We also found that patients receiving indomethacin were mobilised an average of one day before those on placebo.
The intra-osseous pressure, PO2, and PCO2 were measured in 32 hips (21 patients) which were painful but showed no severe degenerative changes. Pre-operative scintigraphy and radiography was performed in all patients. Thirteen hips showed early osteoarthritis, eight had early osteonecrosis, and 11 had no changes. Core biopsies were performed and the bone was examined histologically and graded for necrosis. Histologically, necrosis was present in 27 specimens. Scintigraphic findings did not correlate with the histological results but were more closely related to the radiographic findings. The intra-osseous pressure in hips with histological necrosis (mean 47 mmHg) was significantly higher than in hips without necrosis (mean 26 mmHg). The PO2 was lower in bone with histological necrosis (mean 44 mmHg) than in bone without (mean 71 mmHg). PO2 increased and intra-osseous pressure decreased after decompression. The results confirm that ischaemia plays a central role in the development of necrotic changes in bone. Histological necrosis was found in hips with radiographic signs of osteonecrosis and in those with osteoarthritis. Radiography, and scintigraphy are shown to be insensitive methods for differentiating between those disorders.
In 33 patients who had major amputation for ischemia of the lower extremity, skin blood flow and perfusion pressure were compared in terms of prediction of amputation level. Skin blood pressure was measured photoelectrically. Only the blood flow was known to the surgeon. The primary amputation was performed below the level of the knee in 15 patients, through-knee in 14, and above the knee in only 4 patients. Primary healing was achieved in 27 patients, 5 patients had delayed healing at the same level, and 1 patient was reamputated. The same amputation level was predicted in 24 patients (primary healing/secondary healing/failure = 20/3/1) and a different one in 9 patients. In 4 patients the perfusion pressure suggested a more proximal amputation (2/2/0) and in 5 patients a more distal amputation (all primary healing). There was no difference between the two methods in predicting wound healing.
In order to delineate groups of patients suitable for treatment to prevent heterotopic bone formation (HBF) following total hip replacement, 99 patients were examined to evaluate predisposing factors. One year after surgery, HBF was found in 73% of the patients. A significantly increased frequency of HBF was found among men. There was no correlation between age, severity of osteoarthritis, size of osteophytes, or preoperative hip movement and HBF. Previous ipsilateral hip surgery did not increase the risk of HBF. Although not significant, all patients who developed heterotopic bone after previous ipsi- or contralateral hip surgery showed HBF of the same or even a higher grade after the present replacement.
We recorded intraosseous pO2 in 9 patients with Garden Stage I fractures of the femoral neck during aspiration of the hemarthrosis. An increase in pO2 indicating restoration of the blood flow was seen in 2 of the patients.
We compared intraosseous pressure, partial pressure of oxygen and carbon dioxide, and histopathology in 10 hips with arthrosis and in seven hips with nontraumatic necrosis of the femoral head. Hypoxia of the subchondral bone was present in both conditions. In arthrosis the intraosseous pressure was normal, whereas intraosseous hypertension was present in necrosis. Partial pressure of carbon dioxide was normal in both conditions. Identical signs of subchondral medullary and trabecular necrosis were found in both conditions.
The influence of treatment with indomethacin in the first 6 postoperative weeks on the incidence of early loosening and radiolucencies following cemented total hip replacement were studied in 102 hips. Ninety-nine hips in 99 patients without postoperative antiinflammatory treatment served as control group. One year after surgery, two patients in the indomethacin group and five patients in the control group were suspected of having loosening of one or both prosthetic components. However, no patients had a revision. The lateral acetabular cement-bone interface most frequently showed a radiolucent line. Concerning the incidence of radiolucent lines in any acetabular or femoral cement-bone interface zone, no difference could be shown between the two groups. When evaluated 1 year after surgery, postoperative treatment with indomethacin does not increase the incidence of aseptic loosening or cement-bone interface radiolucencies in cemented total hip replacement.
The erythrocyte sedimentation rate (ESR) was analyzed in 176 patients treated with cemented total hip arthroplasty (THA) for primary osteoarthritis and correlated with the degree of heterotopic bone formation (HBF) one year after the THA. Ninety patients were treated with indomethacin in the first six postoperative weeks, and 86 patients had no antiinflammatory treatment during that same period. The ESR was measured with the Westergren method and estimated preoperatively and six and 12 weeks after THA. Patients treated with indomethacin had no or only Grade I HBF and no significant elevation in the six- and 12-week ESR. In the placebo group, 44 patients (51%) developed Grade II or Grade III HBF, and six weeks after THA, patients with Grade III HBF had a significant elevated ESR when compared with patients without or with Grade I HBF. Moreover, in patients not treated with indomethacin in the first six postoperative weeks, an ESR above 35 mm/hour 12 weeks after THA was found to be a reliable predictor for the development of severe HBF.
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Four frequently referenced radiological methods for assessment of osteoarthrosis in hip joints are compared with respect to their interobserver variation. One hundred hip joints were rated by four observers. Each observer applied all four methods to all the radiographs. The results were analysed by a new statistical method, which allowed detailed assessment of the nature and extent of interobserver variation. Significant differences in terms of intraobserver disagreement were found, and Heripret's method was the best in this respect. All four methods showed a significant degree of systematic disagreement among the observers. This suggests that the interobserver variation might be reduced by confronting the observers with the results of the statistical analysis of their judgements.
We studied the effect of indomethacin on the prevention of formation of heterotopic bone after total hip replacement. In a randomized, double-blind clinical trial involving 201 patients, 102 patients received twenty-five milligrams of indomethacin three times daily for the first six postoperative weeks, and the other ninety-nine patients received a placebo. One year after the operation, eighty-nine of those who had received indomethacin had no sign of heterotopic ossification, and the remaining thirteen had a grade-I lesion. In the group that had received a placebo, twenty-seven had no heterotopic ossification; twenty-four, a grade-I lesion; thirty, a grade-II lesion; and eighteen, a grade-III lesion. Significantly fewer patients who had received indomethacin had formation of heterotopic bone compared with those who had been given a placebo (chi-square test, p less than 0.0005). Only patients who had grade-III formation of heterotopic bone had a significant reduction in movement of the hip.
Serum alkaline phosphatase (SAP) was analyzed in 193 patients treated with total hip arthroplasty (THA) and correlated with the degree of heterotopic bone formation (HBF) one year after surgery. The influence of indomethacin on changes in SAP related to the development of heterotopic bone was studied. Ninety-eight patients received 25 mg of indomethacin three times daily for the first six postoperative weeks; the remaining 95 patients received a placebo treatment. No further anti-inflammatory drugs were allowed during the six weeks. SAP was measured preoperatively and six weeks and 12 weeks after surgery. No patients at risk for developing heterotopic bone after THA could be identified from the preoperative level of SAP. The level of SAP six weeks after THA gradually increased with the amount of HBF. A rise in SAP above 250 IU/liter 12 weeks after surgery was associated with the development of severe heterotopic bone in 13 of 17 patients. Indomethacin inhibited the development of heterotopic bone associated with a rise in SAP following THA. Future studies on HBF and SAP following THA should include information on patient use of anti-inflammatory drugs in the early postoperative period.
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