• Hip and knee surgery

Summary in English

Background and Aim:
Total hip replacement (THA) is a common operation performed on thousands of patients every year in Denmark and throughout the world.
The frequency of complications, especially thromboembolic ones are seldom well described, except for data from the pharmaceutical industry and retrospective database studies. Usually these studies are conducted with other purposes other than describing the complication rates.
The purpose of the ESMOS study was to measure the rate of thromboembolic complications the first 90 postoperative days in an unselected population of THA patients and to analyse predefined risk factors to thromboembolism, knowing that the sample size was probably too small for this.
The secondary aims were to measure the overall number of complications (both surgical and thromboembolic) in a one year follow-up period and to document their time of onsets. Finally, the patients’ improvement in quality of life (QoL), as measured by SF-36, was analysed to determine whether these complications affected QoL during the first post-operative year.

Methods:
500 THA consecutive patients, admitted in the period from January 2004 until May 2005, were included in the study and followed for one year. 565 patients were operated on in this period. 18 refused to participate, 2 were excluded due to the exclusion criteria (age < 18 and foreign citizens) and 45 operations were carried out in periods when the investigator was out of hospital. All variables were collected bedside pre-operatively, peri-operatively and at the fifth post-operative day. Telephone interviews were carried out three and twelve months after the operation. Quality of life was evaluated using pre-operative and one year postoperative SF-36 measurements. Data were double entered in SPSS data entry builder 3.0 and further statistical analyses were performed in SPSS statistical software13.0 (Chicago, Ill. USA). All endpoint data were verified in the patients’ medical files according to predefined criteria. Results: Two patients withdrew their consent after the day 5 follow-up, hence 498 patients could be followed for one year. 24 of the patients (4.8%) experienced at least one serious thromboembolic complication during the first 90 days. After one year 33 (6.6%) of the patients had experienced one such event. Nine patients (1.8%) died in this period, five for reasons related to thromboembolic events, 4 through other causes – mainly cancer. The time of onset of the thromboembolic complications was primarily in the first 30 days after the operation, during which period 60% of the cardiovascular complications had occurred. Logistic regression analysis of risk factors to post-operative thromboembolic complications showed that patients operated with primary THA because of idiopathic osteoarthritis had a reduced risk of thromboembolism than those operated on because of secondary osteoarthritis or revision THA (OR 0.3, 95% Cl: 0.14-0.75). Being over 70 years old (confounded by cement) increased the risk of thromboembolic complications (OR 2.8, 95% Cl: 1.14-6.94). 59 patients (11.8%) had at least one orthopaedic complication directly related to their THA operation. After 90 days (three month) 88% of the orthopaedic complications had been diagnosed. Patients operated on because of idiopathic osteoarthritis had significantly fewer events than the rest of the patients. However, they still had a first year event-rate of 13.0%. 87 (17.5%) of the patients experienced either a surgical or a cardiovascular event within the first year after the operation. The quality of life assessments showed that the great majority of THA patients (both primary and revision THA) gained QoL one year after THA. The only group of patients who lost QoL after THA was the small, but still important group, experiencing deep infection, aseptic loosening or those being re-operated because of malfunction of the prosthesis. Other complications as dislocation, peri-prosthetic fracture and thromboembolic complications did not lead to any decline in QoL, and there was no statistical significant difference in their SF-36 measurements one year postoperatively compared to the complication-free patients. Conclusion: THA is a successful operation in bringing about reduction of pain and improvement in quality of life. However, with the number of overall complications in mind, it is still necessary to be critical in how patients for the hip arthroplasty operation are selected, informed and treated. Due to the limited number of patients and events within this study it was not possible to find pre-operative risk-factors to post-operative thromboembolic events.