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What are common complications from knee replacement surgery?
Executive summary
Knee replacement surgery most commonly produces short-term issues such as stiffness, swelling, and nerve symptoms (paraesthesia), while serious complications — infection, blood clots (DVT/PE), implant failure or need for revision, and peri‑operative medical events — are less frequent but clinically important (examples: joint stiffness 18.5%; overall any complication to 6 months 53.6%; major complications 14.4%) [1]. Multiple patient factors (age, BMI, pulmonary disease) and procedure variables affect complication risk; reporting and definitions vary across studies, so absolute rates differ between sources [2] [3].
1. Common, mostly short‑term problems: stiffness, swelling and sensory changes
Registry and cohort data show that the most frequent complications in the first six months after total knee arthroplasty are joint stiffness (about 18.5%), swelling (≈15.6%), and paraesthesia (sensory disturbance) (≈15.6%), categorized as minor but often meaningful for recovery and function [1]. These problems can prolong rehabilitation and sometimes require additional procedures such as manipulation under anesthesia for stubborn stiffness [1].
2. Infection: uncommon but potentially severe
Deep surgical-site infection is relatively uncommon yet one of the most feared outcomes because it can require long antibiotic courses, washouts, or removal and later replacement of the implant [4] [5]. Several patient information sources and surgical reviews emphasise that infection rates are low — often cited as under about 2% for serious infection — but they carry substantial morbidity when they occur [6] [7] [5].
3. Blood clots (DVT/PE): low frequency, high consequence
Orthopaedic surgery raises the risk of venous thromboembolism; deep vein thrombosis and pulmonary embolism are recognized potential complications that can be life‑threatening if embolization occurs. Guidance commonly includes prophylaxis with anticoagulants and early mobilisation to reduce this risk [4] [8] [5] [9].
4. Implant problems, wear, loosening and revision surgery
Implant loosening, device failure, accelerated wear, and mechanical instability can develop over time and may necessitate revision surgery, especially in younger, highly active, or heavier patients. Manufacturers and medico‑legal summaries also list chronic pain and need for further operations among recognized implant‑related complications [6] [10] [9].
5. Nerve, blood vessel and soft‑tissue injury — rare but real
During the operation there is a small risk of damage to surrounding nerves, arteries, veins, or soft tissues (tendons, ligaments, patella). Most sources describe these events as rare; when they happen they may require repair or lead to prolonged functional problems [4] [11] [7].
6. Medical and peri‑operative complications (cardiac, pulmonary, falls)
Total knee replacement is major surgery and carries the general surgical risks — heart attack, stroke, pneumonia, bleeding, and falls in the immediate postoperative period. These are not always listed as TKA‑specific complications in orthopaedic compendia because definitions vary, but hospitals and patient guides routinely warn they can occur and influence overall risk [3] [12] [5].
7. Who’s at higher risk: age, obesity, lung disease, activity and reporting variability
Multiple sources identify higher complication rates among older patients, those with BMI >30, and those with pulmonary comorbidity; conversely younger, very active patients may face earlier implant wear and higher revision rates [2] [9]. Importantly, The Knee Society workgroup noted that complication reporting is not standardized, so comparisons between studies should be made cautiously [3].
8. How common are complications — numbers differ by study and definition
An Australian registry study reported 53.6% experienced at least one complication within six months (major 14.4%, minor 46.6%), but many “complications” counted there were minor (stiffness, swelling, paraesthesia) [1]. Other patient‑facing sites and surgical reviews emphasize that serious complications such as deep infection are generally under ~2% and death is rare (examples cited: <2% infection; approximate perioperative death rates sometimes reported around 0.5–0.6% in consumer summaries) [6] [10]. Differences reflect study design, follow‑up window and what investigators count as a complication [3].
9. Prevention, management and realistic expectations
Sources recommend risk‑reduction strategies: optimise medical conditions pre‑op (weight, lung health), choose experienced surgeons, use infection and thrombosis prophylaxis, and engage fully in rehabilitation to lower stiffness and clot risks [9] [7] [5]. When complications occur, many are treatable — from antibiotics for wound infection to revision procedures for failing implants — but some require proportionally greater interventions [7] [10].
Limitations and gaps in the available reporting: The provided materials show consistent themes but differ in how they define and count complications; The Knee Society highlighted the lack of standardized reporting [3]. Sources do not provide uniform, single‑number risks for every complication — available sources do not mention a definitive, universally accepted complication rate for every listed outcome [3] [1].