What are common complications after knee replacement surgery?
Executive summary
Knee replacement is common and generally successful, but a range of complications — from early surgical problems like infection and blood clots to later mechanical failure, stiffness, persistent pain and nerve problems — can occur and meaningfully affect recovery and long‑term function [1] [2] [3]. Serious complications are uncommon (often <2% for deep infection), but registry and cohort studies show a substantial share of patients experience at least one minor or major complication within months after surgery [1] [3].
1. Early surgical complications: infection and thromboembolism remain the main immediate worries
Periprosthetic joint infection and venous thromboembolism (DVT/PE) are the highest‑impact early complications clinicians look for: deep infection after total knee arthroplasty is reported in the literature at roughly 0.4–2.0% and can require prolonged antibiotics or removal of the prosthesis, while DVT/PE are recognized causes of readmission and can be life‑threatening if embolization occurs [4] [1] [5].
2. Mechanical problems and longer‑term implant failure that can trigger revision surgery
Implant loosening, polyethylene wear, instability and component failure are leading reasons for later revision; younger, heavier or very active patients are more likely to outlive or stress their implants and face revision surgery down the line [4] [6] [7].
3. Joint stiffness, swelling and persistent pain are common and often underappreciated
A large registry study found that more than half of patients experienced at least one complication to six months, with joint stiffness (~18.5%), swelling (~15.6%) and paraesthesia (~15.6%) among the most frequent minor events; persistent or unexplained pain and dissatisfaction have been reported in up to about 20% of patients in some series [3] [8] [2].
4. Nerve injury and neurological complications: variable, sometimes disabling
Although uncommon overall, injury to nearby nerves — for example peroneal nerve palsy presenting as numbness, paraesthesia or foot drop — is a recognized complication after total knee replacement and requires prompt assessment and specialist follow‑up [8] [7].
5. Medical and systemic complications: cardiac and other non‑orthopaedic events
Non‑orthopaedic events occur after knee arthroplasty and can be serious; population cohorts report new cardiac events (myocardial infarction, heart failure, arrhythmia) in the 90‑day postoperative window in a measurable fraction of patients, and surgeons explicitly counsel that chronic illnesses raise complication risk [4] [1].
6. Who is at higher risk, and what reduces those risks
Obesity, younger age at surgery with greater activity levels, comorbidities and some demographic factors raise the chance of infection, revision or other complications; surgeons and guidelines recommend optimization of health before surgery, thromboprophylaxis, perioperative antibiotics and careful surgical technique as preventive steps [6] [1] [9].
7. Timeline, detection and typical management paths
Early signs of infection or thromboembolism — increasing wound drainage, redness, fever, new leg swelling or shortness of breath — prompt urgent evaluation; many problems are managed with physical therapy, medications and minor procedures, while deep infection, instability or component failure may require reoperation or staged removal of the prosthesis [5] [4] [3].
8. Balancing risk and benefit: the clinical reality behind the numbers
Although complications range from minor and transient to major and limb‑threatening, most patients experience improved pain and function after knee replacement and serious complications remain uncommon; transparent discussion with surgeons about individual risk factors, expectations for activity and the possibility of revision is central to decision‑making [1] [10].