A tourniquet is often used in total knee arthroplasty (TKA) to achieve better visualization, reduce intra-operative bleeding and facilitate cement interdigitation. On the other hand, the associated risks include skin burns, soft tissue and muscle damage, injury of calcified vessels, increased swelling and stiffness of the joints, nerve injury, paralysis, and thromboembolic events. The automatic lower limb pneumatic tourniquet system (Zimmer) was applied to reduce blood loss during surgery. A prospective randomized controlled trial (RCT) was performed to investigate the best tourniquet strategy in TKA. The participants were randomly allocated to groups with different tourniquet strategies: Group 1) tourniquet inflation from skin to cement hardening (skin to cement); Group 2) tourniquet inflation only from cementation (cement only) and Group 3) tourniquet inflation from skin incision to skin closure (skin to skin). In addition to the blood loss and early postoperative outcomes, pain, soft tissue injury, and rehabilitation were also strictly monitored with a longer follow-up duration up to 6 months.

A tourniquet is often used in total knee arthroplasty (TKA) to achieve better visualization, reduce intra-operative bleeding and facilitate cement interdigitation. On the other hand, the associated risks include skin burns, soft tissue and muscle damage, injury of calcified vessels, increased swelling and stiffness of the joints, nerve injury, paralysis, and thromboembolic events.

The automatic lower limb pneumatic tourniquet system (Zimmer) was applied to reduce blood loss during surgery. The skin under the tourniquet was covered by cast padding. The operated leg was elevated and exsanguinated before inflating the automatic pneumatic tourniquet. There are three main strategies for the use of a tourniquet in TKR: A) inflate before incision and deflate following cement hardening ('skin to cement'); B) inflate prior to cement application and deflated following hardening ('cement only'); C) inflate before incision and deflate following completion of skin closure ('skin to skin'). The optimal timing of tourniquet application during primary TKA is still a matter of debate. Most previous reports have failed to show significant differences among different tourniquet strategies.

Kvederas et al. compared these three strategies in a randomized double-blind clinical trial, and demonstrated that the estimated blood loss was highest when the tourniquet was inflated just before cement application and deflated after its hardening ('cement only'), while inflation of tourniquet before skin incision and its deflation after hardening of cement ('skin to cement') tends to give better early postoperative mobilization. However, this was an interim report with limited number of patients, and only limited outcome parameters were reported, which were insufficient to draw firm conclusions regarding the differences in outcome.

Therefore we performed this prospective randomized controlled trial (RCT) with a decent sample size to investigate the best tourniquet strategy in TKA. In addition to the blood loss and early postoperative outcomes, we also strictly monitored pain, soft tissue injury, and rehabilitation with a longer follow-up duration up to 6 months.

All of the operations were performed through the medial parapatellar approach by the same experienced joint replacement surgeon. All patients underwent primary TKA with minimally invasive techniques and cemented prostheses (EvolutionTM medial pivot, MicroPort, USA). An intramedullary guide was used for both tibial and femoral cuts.

The automatic lower limb pneumatic tourniquet system was applied to reduce blood loss during surgery. The skin under the tourniquet was covered by cast padding. The operated leg was elevated and exsanguinated before inflating the automatic pneumatic tourniquet. One of the three tourniquet treatment strategies was used, as determined by the group allocation of the patient. In all the three groups, the tourniquet was inflated to a pressure of 280 mm Hg. The wound was closed after wound irrigation and hemostasis and then was wrapped with elastic bandages. One drainage was applied postoperatively in all patients and was kept until 24h to monitor blood loss.

Inclusion Criteria:

1. Patients suffer from primary osteoarthritis indicated for total knee arthroplasty
2. Subject is physically and mentally willing and able to comply with the postoperative scheduled clinical and radiographic evaluations
3. Subject must have signed an informed consent document specific to the study, and approved by the Ethics Committee, indicating that they understand the purpose of and procedures required for the study and are willing to participate in the study

Exclusion Criteria:

1. Subject requires a revision knee arthroplasty surgery
2. Subject is currently on anti-coagulant therapy or has coagulopathy
3. Subject has peripheral vascular disease of the lower limb evidenced by the presence of blood vessel calcification on the radiographs or the absence of dorsalis pedis/popliteal pulses
4. Subject suffers from conditions other than primary knee osteoarthritis, e.g. inflammatory arthritis
5. Subject having associated medical diseases affecting rehabilitation
6. Subject has active systemic infection or infection near the knee joint
7. Subject having current medical condition that render them unfit for surgery
8. Any criterion which in the opinion of the investigator, suggests that the subject would not be compliant with the study protocol