While knee replacement surgery has a very high success rate, it can also cause side effects, includingnumbness of the skinaround the incision site.
Sensory nerves detect sensations like pressure, light touch, and vibrations. These small nerves are branches of larger nerves connecting the brain to all parts of the body. Damage at any level of this connected pathway can lead to areas of abnormal sensation in the body—including numbness.
Duringknee replacement surgery, it’s common for nerves that run through the surgical site to become damaged. This can result in numbness around the knee incision. While this minor complication doesn’t typically cause a person any problems, it can last for a long time or even be permanent.
Knee Replacement Incisions
Knee replacement incisions can vary slightly based on surgeon preference, surgical approach, and the implants used. A traditional knee replacement incision is placed directly over the front of the knee. This incision, called a midline incision, is the most common surgical approach for performing total knee replacement.
Other surgical incision options include a medial parapatellar incision and a subvastus oblique incision, both of which are oriented more towards the inner (medial) side of theknee joint. In these situations, a surgeon will shift the incision slightly so that the scar is not directly over the front of the kneecap.
The length of the surgical incision can vary dramatically. In one study, investigators found the average length of a knee replacement incision to be just over 11 cm, but this varied from about 7 cm up to a length of about 19 cm.
Your body has small, delicate skin sensation nerves that lie directly underneath the skin and cross the area of a knee replacement incision. There is essentially no way to completely avoid the skinnerveswhen performing knee replacement surgery.
When your surgeon makes the initial incision and dissects down to the knee joint, those skin nerves are invariably severed. Even if it were possible to protect the skin nerves at the time of the initial incision, preserving them while trying to perform the necessary steps to prepare and implant an artificial knee would be challenging.
How Common Is Numbness?
In addition to these factors, the nerve that provides sensation to the front of the knee starts on the inner side of the joint and progresses over the front of the joint toward the outer side of the knee. When the incision is based more toward the inner side of the knee joint, it is more likely to cut the larger portion of the nerve. Incisions based more towards the outer side of the joint tend to involve smaller nerve branches. When only the smaller branches are cut, perceived numbness may be reduced.
Regarding the difference noted in the perception of numbness between men and women, the reason is unclear. Studies have not shown any gender difference in the orientation of the skin nerves. Some perceived numbness might be due to differences in clothing. Women specifically mentioned being bothered when wearing skirts or dresses that tended to rub against incisions.
What to Do
There is not a lot that can be done about numbness around an incision after a knee replacement. Uncomfortable sensations may diminish over time, and there may be some recovery of normal sensation to the area. Most people who notice symptoms of numbness find that the area gradually shrinks down over time.
Nerve recovery after damage and nerve regeneration are both very slow processes. While full recovery of nerve sensation may be unlikely, it may take one year or longer for abnormal sensations to recover to the fullest extent possible. Complete recovery of all nerve sensations is unlikely.
A Word From Verywell
On a positive note, having abnormal sensations around a knee replacement incision does not lead to limitations in the function of the knee joint.In addition, abnormal sensations may continue to improve for a year or more from the time of surgery.
4 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Orthopaedic Surgeons. OrthoInfo.Total knee replacement.Sanna M, Sanna C, Caputo F, Piu G, Salvi M.Surgical approaches in total knee arthroplasty.Joints. 2013;1(2):34–44.McPherson E, Czarkowski B, Dipane M, Sherif S.Incision length in small incision total knee arthroplasty: how long of an incision is needed?Reconstructive Review.2015;5(1). doi:10.15438/rr.5.1.102Jariwala AC, Parthasarathy A, Kiran M, Johnston LR, Rowley DI.Numbness around the total knee arthroplasty surgical scar: prevalence and effect on functional outcome.J Arthroplasty. 2017;32(7):2256-2261. doi:10.1016/j.arth.2017.01.057
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Orthopaedic Surgeons. OrthoInfo.Total knee replacement.Sanna M, Sanna C, Caputo F, Piu G, Salvi M.Surgical approaches in total knee arthroplasty.Joints. 2013;1(2):34–44.McPherson E, Czarkowski B, Dipane M, Sherif S.Incision length in small incision total knee arthroplasty: how long of an incision is needed?Reconstructive Review.2015;5(1). doi:10.15438/rr.5.1.102Jariwala AC, Parthasarathy A, Kiran M, Johnston LR, Rowley DI.Numbness around the total knee arthroplasty surgical scar: prevalence and effect on functional outcome.J Arthroplasty. 2017;32(7):2256-2261. doi:10.1016/j.arth.2017.01.057
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Orthopaedic Surgeons. OrthoInfo.Total knee replacement.Sanna M, Sanna C, Caputo F, Piu G, Salvi M.Surgical approaches in total knee arthroplasty.Joints. 2013;1(2):34–44.McPherson E, Czarkowski B, Dipane M, Sherif S.Incision length in small incision total knee arthroplasty: how long of an incision is needed?Reconstructive Review.2015;5(1). doi:10.15438/rr.5.1.102Jariwala AC, Parthasarathy A, Kiran M, Johnston LR, Rowley DI.Numbness around the total knee arthroplasty surgical scar: prevalence and effect on functional outcome.J Arthroplasty. 2017;32(7):2256-2261. doi:10.1016/j.arth.2017.01.057
American Academy of Orthopaedic Surgeons. OrthoInfo.Total knee replacement.
Sanna M, Sanna C, Caputo F, Piu G, Salvi M.Surgical approaches in total knee arthroplasty.Joints. 2013;1(2):34–44.
McPherson E, Czarkowski B, Dipane M, Sherif S.Incision length in small incision total knee arthroplasty: how long of an incision is needed?Reconstructive Review.2015;5(1). doi:10.15438/rr.5.1.102
Jariwala AC, Parthasarathy A, Kiran M, Johnston LR, Rowley DI.Numbness around the total knee arthroplasty surgical scar: prevalence and effect on functional outcome.J Arthroplasty. 2017;32(7):2256-2261. doi:10.1016/j.arth.2017.01.057
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