Introduction: Risk-profiling of patients in hip arthroplasty to prepare for perioperative complications is becoming more important. Materials and Methods Major complications (haematoma, cardiovascular complication, deep venous thrombosis, pulmonary embolism, joint infection, injuries of neurovascular structures and pneumonia) following 29994 hip arthroplasties occurring within the postoperative hospitalisation period have been documented based on a standardised protocol used for external quality assessment in Germany. Using logistic regression, the influence of potential risk factors was assessed for their significance on postoperative complications and univariate analysis was used to assess this influence on every single major complication. The influence of patient age and the surgery time on major complications were calculated using ANOVA.

Results: Major perioperative complications occurred in 7,26 per cent. Haematomas were reported in 3.22, cardiovascular complications in 1.55, joint infections in 0.94, injuries of neuro-vascular structures in 0,63, deep venous thrombosis in 0.37, pulmonary embolism in 0.26 and pneumonia in 0.28 per cent of all cases. Patient age, length of surgery and allogeneic blood transfusion significantly increased the rate of major perioperative complications. Increased patient age increased the risk for all major complications but neuro-vascular injuries. Increased surgery time elevated the risk for all major complications except haematoma. Allogeneic blood transfusions were associated with an elevated risk for all major postoperative complications except deep venous thrombosis. In contrast, autologous blood transfusions did not increase the risk for suffering a postoperative complication. Surprisingly, gender did not have a significant influence on the occurrence of immediate postoperative complications. Conclusions Allogeneic blood transfusion, increased age and surgery time contribute to an elevated incidence of perioperative complications following hip arthroplasty.

Introduction: Minimal-invasive techniques in total joint replacement are perceived to reduce soft tissue trauma. In TKR, reduced exposure during surgery bares the risk of component malpositioning. Therefore we have combined minimal invasive surgical techniques with non-CT based navigation in TKR. The purpose of this observational study is to describe first results of a controlled observational study comparing minimal invasive navigated total knee arthroplasty (MINI-NAV-TKR) to open navigated total knee arthroplasty (NAV-TKR) with respect to component positioning, surgery time and immediate postoperative complications.

Materials and Methods: From June to September 2004, 26 MINI-NAV-TKR and 33 NAV-TKR have been performed by five surgeons in an unselected group of patients. In both groups, preoperative deformation of the mechanical leg axis was compared to postoperative mechanical leg axis using total one-leg standing radiographs. To control the safety and reproducibility of both procedures, time of surgery and postoperative complications were compared among both groups.

Results: Given informed consent, 17 females and 9 males received 26 MINI-NAV-TKR, mean age was 71,06 years (ranging from 56,24 years to 84, 35 years), mean BMI was 28,8 kg/m2 and preoperative mechanical leg axis ranged from 18o varus to 16 o valgus. In NAV-TKR group, 12 males and 21 females at a mean age of 68,75 (range 51,97 to 86,73 years) received 33 TKR, mean BMI was 30,6 kg/m2 and preoperative mechanical axis ranged from 11 varus to 20 valgus. Postoperative radiographic leg alignment in the MINI-NAV-TKR group ranged from 1 degree valgus to 3 degree varus mechanical axis as compared to the NAV-TKR that ranged from 1 valgus to one outlayer of 4 degree varus. Time of surgery significantly differed among the groups (mean time Mini-NAV-TKR 115,23 min versus mean time NAV-TKR 98,15 minutes, p=0,002). In the MINI-NAV-TKR group 1 postoperative pin-infection and one conversion to an open procedure have been reported, in the NAV-TKR group 2 hematomas have been described.

Conclusion: Despite increased mean time of surgery in the MINI-NAV-TKR group, component positioning and complications are comparable between both groups. These preliminary results indicate, that MINI-NAV-TKR combined with navigation is a safe and reproducible method.

Introduction: Risk-profiling of patients in knee arthroplasty to prepare for postoperative complications is becoming more important.

Materials and Methods: Major complications (hematoma, cardio-vascular complication, deep venous thrombosis, pulmonary embolism, joint infection and pneumonia) following 17644 knee arthroplasties occurring within the postoperative hospitalization period have been documented based on a standardized protocol used for external quality assessment in Germany. Using logistic regression, the influence of potential risk factors were assessed for their significance on postoperative complications and uni-variate analysis used to assess this influence on every single major complication. The influence of patient age and the surgery time on major complications were calculated using ANOVA.

Results: Major postoperative complications occurred in 7.22 per cent with hematoma in 2.89, cardio-vascular complications in 1.79, deep venous thrombosis in 1.23, pulmonary embolism in 0.23, joint infection in 0.82 and pneumonia in 0.25 per cent. Patient age, surgery time, gender, high classification according to the American Association of Anesthesiologists, allogeneic blood transfusion and lateral release significantly increased the rate of postoperative complications. Males are more prone to suffer from hematoma, joint infection and pneumonia in the immediate postoperative course. Females are more endangered for deep venous thrombosis. Extended surgery time increased the rate of hematoma and infection, increased patient age elevated the rate of hematoma, cardiovascular complication and pneumonia. Alloge-neic blood transfusion increased the risk of all major complications except deep venous thrombosis.

Conclusions Male gender, allogeneic blood transfusion, increased age and surgery time elevate immediate postoperative complications following knee arthroplasty.