summary TKA Stiffness is a common complication following TKA that results in poor postoperative functional outcomes. Diagnosis is made clinically in a patient with a TKA who has flexion < 90 degrees or a flexion contracture of 10-15 degrees. Treatment is manipulation under anesthesia for flexion < 90 degrees within first 12 weeks of surgery. Arthroscopic lysis of adhesions is indicated for flexion < 90 degrees after 12 weeks. Epidemiology Incidence 1.3%-12% Risk factors preoperative factors poor preoperative ROM most important factor patella baja younger age (< 55) smoking increased medical comorbidities low pain tolerance prior surgery technical factors overstuffing patellofemoral joint malrotation tight flexion and/or extension gaps joint line elevation excessive tightening of extensor mechanism during closure closure in flexion (as opposed to extension) may limit this complication tight PCL in cruciate-retaining prosthesis postoperative factors delayed rehabilitation infection HO hamstring spasms usually resolves within 6 months Presentation Symptoms difficulty kneeling Physical exam check preoperative ROM from records flexion contracture 10-15 degrees flexion < 90 degrees Imaging Radiographs rule out prosthesis malposition or alignment CT scan rule out prosthesis malposition or alignment Studies Serum labs ESR/CRP must rule-out infection Treatment Nonoperative manipulation under anesthesia indications flexion <90 degrees within first 12 weeks of operation (timing is controversial) over aggressive manipulation fracture extensor mechanism disruption contraindications stiffness >3 months postoperatively manipulation associated with greater risk and lower benefit Operative arthroscopic lysis of adhesions with manipulation under anesthesia indications persistent late stiffness revision total knee arthroplasty indications identifiable technical cause for stiffness