When joint damage from severe arthritis or injury becomes debilitating, surgical intervention is often the most effective path to restoring mobility and eliminating chronic pain. This severe joint deterioration requires a fundamental change to the knee structure, leading many patients to search for the least invasive options available, such as arthroscopy.
Defining the Procedures: Arthroscopy Versus Replacement
The direct answer to whether a full knee replacement can be performed arthroscopically is no, due to the fundamental differences in the procedures. Arthroscopy is a minimally invasive technique that uses small incisions, typically about one centimeter long, to insert a camera and specialized instruments into the joint space. This method is primarily used for diagnosis, cleaning out debris, or repairing structures like a torn meniscus or damaged ligaments, which preserves the native joint.
Knee replacement, or arthroplasty, is an extensive open surgery that requires the physical removal of damaged bone and cartilage from the femur and tibia. The procedure necessitates the implantation of large metal and plastic prosthetic components, which must be perfectly aligned and secured with bone cement or a porous coating for bone ingrowth. The size of the implants and the instruments needed to resect the bone make the process incompatible with the small entry ports of arthroscopy. While arthroscopy repairs the existing joint, replacement substitutes it entirely.
The Standard Approach: Total Knee Arthroplasty
Total Knee Arthroplasty (TKA) is the traditional and most common form of knee replacement, reserved for patients with widespread joint damage across two or three compartments of the knee. This procedure requires a longer incision, typically measuring between 8 and 10 inches, to provide the surgeon with the necessary visibility and access. The surgery involves exposing the entire knee joint by carefully moving the patella and manipulating the surrounding soft tissues.
The surgeon uses precise cutting guides and specialized tools to remove the damaged ends of the thigh bone (femur) and the shin bone (tibia). After removing the diseased surfaces, the metallic components are fixed onto the prepared bone, and a polyethylene spacer is placed between them to act as the new cartilage surface. This comprehensive resurfacing requires a large surgical field, which is necessary for accurately fitting a durable prosthetic joint.
Minimally Invasive Knee Replacement Techniques
The confusion about “arthroscopic replacement” often stems from the development of Minimally Invasive Surgery (MIS) techniques for knee replacement. MIS-TKA is an open surgery, not an arthroscopic one, but it focuses on reducing the size of the incision and minimizing damage to the surrounding soft tissues. The incision length is typically shorter than the traditional approach, often measuring 4 to 6 inches, and specialized instruments are used to operate through this smaller opening.
A primary goal of MIS-TKA is to utilize quadriceps-sparing approaches, such as the subvastus or midvastus techniques, which avoid cutting through the main quadriceps tendon. By separating or splitting the muscle fibers instead of severing the tendon, the surgeon aims to reduce post-operative pain and facilitate a quicker recovery of muscle function. The implants used in MIS-TKA are the same as those in traditional TKA.
Another less invasive option is Unicompartmental Knee Arthroplasty (UKA), or partial knee replacement. This procedure is appropriate when the arthritis is confined to just one of the knee’s three compartments, often the medial side. The UKA involves replacing only the damaged compartment, leaving the healthy cartilage and ligaments intact. Because less bone is removed and the surgery is more localized, the incision is smaller than an MIS-TKA, making it the least invasive replacement option.
Comparing Recovery and Patient Candidacy
The choice between a traditional TKA, MIS-TKA, or UKA significantly impacts the patient’s recovery trajectory and is determined by specific candidacy requirements. Patients undergoing MIS-TKA and UKA generally experience less post-operative pain, a shorter length of hospital stay, and a faster return to daily activities compared to those receiving a traditional TKA. This accelerated recovery is primarily due to the decreased soft-tissue and muscle disruption inherent in these less invasive techniques.
Not all patients are candidates for the less invasive approaches; patient selection is highly specific, particularly for UKA. Partial knee replacement is reserved for younger, healthier patients who are not obese, have a stable knee joint, and have arthritis limited to one compartment. Patients with severe, widespread arthritis, significant knee deformity, or a high body mass index require the more comprehensive access and resurfacing provided by a traditional or MIS-TKA to ensure a successful, long-lasting outcome.