**4. Timing of tourniquet release**

Pfitzner et al. found that the use of a tourniquet in primary TKA increased the tibial cement

The use of a tourniquet can be an important issue but still controversial regarding the formation of deep vein thrombosis (DVT) after TKA. Abdel-Salam and Eyres [44], Mori et al. [10], and Tai et al. [5] reported an increased incidence of DVT with the use of a tourniquet in TKA, but Wakankar et al. [35] and Fukuda et al. [23] both reported that the incidence of DVT was not related to the use of a tourniquet. However, these studies vary in diagnostic tool, race, and

The length of tourniquet time (ischemic duration) is another factor affecting the risk of thrombosis. Bin Abd Razak et al. [45] and Chung et al. [46] reported that the rate of DVT appeared to be associated with prolonged tourniquet time, probably due to a long period of venous stasis and damage to calcified vessels. Early deflation of tourniquet is also found to decrease

Although most DVTs were asymptomatic, an asymptomatic postoperative DVT is associated with an increased risk of the late development of the post-thrombotic syndrome [48, 49].

Wound condition after TKA is important for the prevention of periprosthetic infection [50, 51]. Delay in wound healing is associated with deep infection, which leads to the

The use of a tourniquet is associated with a higher incidence of postoperative wound problems [3, 5, 28, 44], including significant hematoma, wound oozing, skin blistering, bruising, necrosis, and superficial wound infection requiring antibiotics treatment. Circulatory stasis caused by tourniquet inflation may worsen the local soft tissue condition [5]; furthermore, reactive hyperemia and activation of fibrinolytic cascade after tourniquet release increase the tissue pressure and local inflammation [3, 53], all of which lead to tissue hypoxia and subsequently

For patients who undergo tourniquet-controlled TKA, thigh pain is a very common complaint during the early postoperative period. Performing TKA without a tourniquet could reduce postoperative thigh pain in several literature [1, 3, 12, 13], but the benefit declines with time

Compromised knee motion after tourniquet use has also been mentioned in some literature [35, 40, 44]. The possible reasons are as follows: (1) using a tourniquet may injure the nerve and the skeletal muscle, even causing rhabdomyolysis [40, 54] and (2) increased postoperative

Thus, patients with an asymptomatic DVT should be monitored carefully.

mantle thickness [42], which could increase implant stability and survival [43].

**3.4. Risk of thrombosis**

84 Primary Total Knee Arthroplasty

the presentation of symptoms.

the risk of DVT [18, 47].

arthroplasty failure [52].

compromised wound healing.

**3.5. Complication related to wound healing**

**3.6. Thing pain, weakness, and postoperative recovery**

and becomes insignificant different at follow-ups longer than 6 months.

pain would limit the patient's ability to perform postoperative training [40, 55].

To reduce the ischemic duration and the incidence of complications aforementioned, some surgeons suggested the early release of tourniquet. The different timings of tourniquet deflation include immediately after wound closure [22], after a tight arthrotomy closure [21] and mostly after the implantation of the prostheses [18, 20, 32].

Although there were some reviewing articles related to the timing of tourniquet release in TKA, the results varied. For blood loss, Huang et al. [59] and Zan et al. [47] suggested that tourniquet release before wound closure for hemostasis wound significantly increase not only total measured blood loss but also calculated blood loss. Zhang et al. [31] found that releasing tourniquet before wound closure could increase only total blood loss. However, Tie et al. [60] reported no significant difference existed in calculated blood loss nor total blood losses. To analyze the blood loss in detail, intraoperative blood loss may contribute to most of increased blood loss. Releasing tourniquet before wound closure theoretically could ensure a better view of hemostasis, and patients would have better blood conservation. Nevertheless, fibrinolytic activity rises after the release of an arterial tourniquet [61], contributing to the higher perioperative blood loss. In addition, it was impossible to find all bleeding sources, especially the oozing spots. These are the reasons why total blood loss is higher when tourniquet is released before wound closure in some reviewing article.

Several studies demonstrated that releasing tourniquet before wound closure had a decreased risk of postoperative complications such as wound complications [22], deep infection, DVT [31], and so on [47, 60, 62]. Although there is no significant difference in some meta-analysis [18, 59], it had a trend that releasing tourniquet before wound closure could decrease the incidence rate of major complication.
