The comparison of wound drainage after TKA between postoperative cast immobilization and nonimmobilization: a randomized controlled trial

Background: Many previous studies concluded that postoperative splint did not significantly decrease volume of blood loss in suction drainage. However, the splints in their studies were not rigid. We applied long leg cast, that was more rigid and subsequently may reduce blood loss in suction drainage.

Objectives: This study compared the blood from suction drainage after total knee arthroplasty between postoperative cast immobilization and non-immobilization.

Methods: A consecutive series of 142 knees in 142 osteoarthritis patients who required total knee arthroplasty were divided in long leg cast group and non-cast group (webril and elastic bandage wrapped) by close seal envelopes. Both groups removed their restrained at three days post operation. The volumes of blood from suction drainage in both groups were recorded for 24 hours after operation. Maximum knee flexion and wound complication were also evaluated.

Results: There were 69 knees in cast group and 73 knees in non-cast group. The mean±SD of blood loss in cast group was 324.7±129.3 ml and non-cast group was 546.8±122.2 ml. The mean difference in blood lost between cast and non-cast group were 222.1 ml (range from 180.4 to 263.8 ml.). Using unpaired t-test, there was a significant difference of wound drainage between both groups (p < 0.05). More maximum knee flexion at eight weeks postoperative was gain in cast group (p < 0.05). Wound complications were increase in non-cast group but not statistically significant (p = 0.497).

Conclusion: The immobilized knee with long leg cast after total knee arthroplasty can decrease blood loss from suction drainage. Therefore, we recommended using long leg cast after total knee arthroplasty as another technique that safely reduces blood loss without compromise to postoperative range of motion in patient who need blood saving as critical.