Tammachote 2013.

Methods	Partially blinded, randomized, controlled trial Computerized block randomization; sealed opaque envelopes Follow‐up: 12 weeks
Participants	Subjects: 59 participants enrolled (57 analysed and followed up to 12 weeks) from one university hospital: Thammasat University, Pathumthani, Thailand Operation: primary total knee replacement 2 groups (of 28 and 29 people) Mean age (SD): control group, 69 (± 8); experimental group, 70 (± 7) Sex: control group, 8 males and 20 females; experimental group, 3 males and 26 females
Interventions	Spinal anaesthesia using 2.5 mL of 5 mg/mL isobaric bupivacaine Control group: 0.2 mg intrathecal morphine sulphate Experimental group: periarticular infiltration 100 mg bupivacaine (5 mg/mL, 20 mL), 5 mg morphine sulphate (5 mL), 0.6 mg epinephrine (0.6 mL), 30 mg ketorolac tromethamine (1 mL), and 73.4 mL saline (total volume: 100 mL). The first 25 mL were injected into the posterior knee capsule and soft tissue around the medial and lateral collateral ligaments before implantation. Quadriceps muscle, retinacular tissues, pes anserinus, and suprapatellar and infrapatellar fat pad, then infiltrated with the rest of the mixture. Postoperative analgesia: IV ketorolac PCA for 48 hours: bolus dose 0.6 mg, lockout time 2 minutes; maximal dose 15 mg/4 h 1300 mg paracetamol PO every 8 hours Amitriptyline 10 mg every day On POD 3, PCA discontinued; 250 mg naproxen PO twice daily, and 50 mg tramadol every 6 hours as needed for breakthrough pain
Outcomes	Primary outcomes: Ketorolac use through PCA during every 4‐hour interval until 48 hours after surgery VAS every 4 hours until 48 hours postoperative Secondary outcomes: Morphine‐related side effects Blood loss collected in closed suction drainage ROM at 2, 6 and 12 weeks Modified Thai version of the WOMAC score (at 6 and 12 weeks)
Funding source	Not provided
Declarations of interest	None reported
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Computerized block randomization was done by an independent research assistant (TY) who otherwise was not engaged in the study. The anaesthesiologist assistant nurse, who opened sealed opaque envelopes containing the randomization result, allocated patients into each group."
Allocation concealment (selection bias)	Low risk	"The anaesthesiologist assistant nurse, who opened sealed opaque envelopes containing the randomization result, allocated patients into each group."
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Personnel was not blinded. It is unclear whether participants were blinded or aware of their group assignment.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"A clinical investigator (SK) who was not aware of the randomization collected demographic data, preoperative clinical conditions using predesigned data sheets, and perioperative data, and entered them in a database." However, there is no mention of blinding of the assessor of the long‐term outcome.
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Two knees were excluded from analysis because one had drain dislodgement before 48 hours and the other had a periprosthetic fracture (Lewis and Rorabeck Type 2) from an accident 6 weeks after surgery."
Selective reporting (reporting bias)	Low risk	All outcomes were reported.