A total knee arthroplasty (TKA), commonly known as knee replacement surgery, resurfaces the damaged knee joint with artificial components (prostheses). This surgery primarily relieves pain and restores function in knees severely affected by conditions like osteoarthritis. While the main focus is replacing the ends of the thighbone (femur) and shinbone (tibia), the surrounding soft tissues, including the bursa, are also encountered. A bursa is a small, fluid-filled sac that cushions the joint. This article details the role of the bursa and its fate during knee replacement surgery.
Understanding the Bursa in the Knee Joint
The knee joint is surrounded by several bursae, which are thin, slippery sacs filled with lubricating fluid. Their primary purpose is to reduce friction between bone, tendons, and skin as the joint moves. By providing a smooth, gliding surface, bursae prevent wear and tear on the soft tissues that cross the knee.
The knee has multiple bursae, including the prepatellar, infrapatellar, and pes anserine bursae. The prepatellar bursa, located in front of the kneecap, is often inflamed by excessive kneeling (“housemaid’s knee”). The infrapatellar bursa lies beneath the kneecap tendon, and the pes anserine bursa is found on the inner side of the knee.
The Fate of the Bursa During Total Knee Arthroplasty
Bursa removal during knee replacement is often incidental rather than intentional. During TKA, the surgeon must make an incision and access the joint surfaces, which frequently disrupts the soft tissues around the kneecap. The standard midline incision naturally passes through the area of the prepatellar bursa.
Surgeons often partially excise or disturb the bursa to gain the necessary visualization and access to the femur and tibia for precise implant placement. This disturbance is a byproduct of accessing the deeper joint structures, not a dedicated bursectomy aimed at removing the entire sac. The bursa’s integrity is often compromised simply due to the surgical exposure required.
In most routine procedures, the bursa is not deliberately excised unless there is a specific pre-existing pathology. The focus remains on replacing the damaged cartilage and bone. Complete removal is reserved for cases where the sac itself is diseased or problematic.
When Removal Becomes Necessary
A complete and dedicated removal of the bursa, known as a bursectomy, is performed only when the tissue is chronically diseased. This intentional removal is considered a necessary procedure alongside the TKA.
Conditions that mandate bursectomy include:
- Chronic, non-resolving bursitis.
- The presence of calcification within the bursal sac.
- An active infection, known as septic bursitis.
In cases of severe, chronic bursitis, the bursa walls can become thickened and scarred, risking post-operative recurrence or complications. Removing the problematic sac eliminates a potential source of long-term inflammation and pain. If a massive bursa is present, the surgeon may decide to remove it simultaneously with the TKA or perform the procedures in two separate stages to minimize wound healing risks.
For an infected bursa, removal is strongly considered because leaving the infected tissue behind could compromise the new joint implant. Bursectomy is a deliberate step taken only when the bursa poses a risk to the patient’s recovery or the success of the knee replacement.
Recovery and Long-Term Implications
Following a TKA, patients commonly experience localized swelling (effusion) near the knee, regardless of whether the bursa was disturbed or removed. This normal post-surgical response to tissue trauma is managed with ice, compression, and elevation. If the original bursa was completely excised, the body’s natural healing process often leads to the eventual regeneration of a new bursa over time.
Patients may develop new bursal issues after the knee replacement, such as pes anserine bursitis, which causes pain on the inner side of the knee. This occurs because the soft tissues surrounding the joint can become inflamed due to new stresses or altered mechanics from the implant. These issues are typically treated with non-surgical methods like anti-inflammatory medication or targeted steroid injections.
The risk of recurrence after a dedicated bursectomy is generally low. For most patients, the surgical disruption or removal of the bursa during TKA does not lead to long-term complications related to the sac itself. Successful recovery is primarily determined by managing post-operative swelling and following physical therapy protocols.