PURPOSE OF THE STUDY Information that would help physicians make decisions and improve the likelihood of achieving the desired results of medical interventions is sought as part of the concept of the individualized approach to patients. The primary purpose of our study was to identify which features determine the higher/lower likelihood of the need for early reoperation after a TKA (total knee arthroplasty). The successful preoperative identification of high risk patients could lead to the adjustment of the surgical procedure and thus lower the percentage of revision surgeries. MATERIAL AND METHODS In total, 826 patients (296 men and 530 women) were included in our prospective study; these patients underwent TKA implantation at our department between September 2010 and March 2015. The average age of the patients at the time of primary TKA implantation was 68.9 years. Over 60 preoperative and perioperative parameters were tracked and continuously recorded in our arthroplasty register. First, conventional analysis of individual parameters was carried out and odd ratios for their relationship with revision surgeries were set. Subsequently, the data were transformed into a graph and methods of complex network analysis were applied to identify such combinations of features (parameters) that would significantly separate the operated patients into homogeneous subgroups. The observed patient subgroups were then reanalyzed for parameters related to reoperations. RESULTS Thirty-three patients (4% of those studied) required early TKA revision (within 3 years of primary implantation). The most frequent reason for revision surgery was an early postoperative infection. The analysis of observed characteristics proved that the likelihood of revision surgery was by 80% lower in women in comparison with men. Other parameters associated with a higher frequency of reoperations were the level of preoperative activity, smoking and the waiting time for the first operation. Patients waiting for primary TKA implantation for more than 3 months showed a 2.7 times greater likelihood of revision surgery when compared to those who were operated within 3 months after the indication to surgery. Patients declaring medium or high activity levels (assessed by means of the UCLA scale) had a 2.1 times higher likelihood of revision surgery in comparison to patients with low physical activity levels. Smoking meant up to 3.2 times greater likelihood of revision in comparison with non-smokers. Conversely, no correlation between a greater risk of reoperation and age, BMI (body mass index) or the level of comorbidities evaluated by means of the Charlson scale was confirmed. No correlation between the risk of revision and primary diagnosis was found either. DISCUSSION The frequency of early TKA revision surgeries (within 3 years after the primary surgery) in the evaluated sample is relatively high (4%). On the contrary, the reasons for early revisions correspond with recent publications. The risks of TKA infection overlap with the predictors of wound healing disorders to a great extent. Smoking, obesity and comorbidities decreasing the efficiency of the immune system are mentioned most frequently. Patients waiting for TKA implantation longer were more inclined to require early revision surgery too. Awareness of this fact is reflected in the tendency to shorten the waiting time for TKA surgery. A number of studies have pointed out the negative influence of longer waiting times on postoperative results. In our study, it was men who required revision most frequently, specifically the group of those having smoking and higher physical activity in their case histories. The influence of smoking on early postoperative morbidity is also well known. A significant finding is that stopping smoking can decrease the probability of early reoperation. However, we failed to explain the influence of higher physical activity. The influence of patients ́ age, BMI, level of comorbidities or primary diagnosis on the frequency of revision surgeries were not demonstrated. CONCLUSIONS We proved that women definitely show a lower risk of early TKA revision surgeries in comparison with men. A higher frequency of reoperations was related to modifiable factors such as smoking, longer waiting times for the primary operation, and a higher preoperative level of physical activity. A significant finding is that stopping smoking could decrease the probability of early TKA revision. Nonetheless, we do not recommend decreasing preoperative physical activity at this point; it will require further studies and verification of this finding. Also, the potential mechanism of the influence of greater preoperative load on the particular reason for revision is yet to be explained.

Katedra informatiky Fakulta elektrotechniky a informatiky Vysoké školy báňské Technické univerzity Ostrava

Ortopedická klinika Lékařské fakulty Univerzity Palackého v Olomouci a Fakultní nemocnice Olomouc

Ústav imunologie Lékařské fakulty Univerzity Palackého v Olomouci a Fakultní nemocnice Olomouc

Smoking, preoperative activity, and waiting time for the surgery could predict the risk of early reoperation in total knee arthroplasty

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