27447

Total knee arthroplasty, primary

CPT code 27447 represents a primary total knee arthroplasty, a major orthopedic surgical procedure performed to replace the diseased or damaged surfaces of the knee joint with artificial components. This surgery is typically undertaken to alleviate severe knee pain, correct significant deformity, and restore function in patients suffering from end-stage arthritis or other debilitating knee conditions. The procedure begins with an incision, usually made along the front of the knee, to expose the joint. The surgeon then meticulously removes the worn-out cartilage and a thin layer of underlying bone from the distal end of the femur (thigh bone), the proximal end of the tibia (shin bone), and often the posterior surface of the patella (kneecap). Specialized instruments are used to precisely shape the bone ends to ensure proper fit and alignment of the prosthetic implants. The femoral component, typically made of a metal alloy, is secured to the end of the femur. The tibial component consists of a metal tray that is fixed to the top of the tibia, usually with a durable polyethylene plastic insert placed between the femoral and tibial components to allow for smooth gliding motion. A patellar component, made of polyethylene, may also be cemented to the back of the kneecap. Most commonly, these components are affixed to the bone using bone cement, though some prostheses are designed for uncemented or 'press-fit' fixation. The ultimate goal is to reconstruct a stable, mobile, and pain-free joint. Post-operatively, an intensive rehabilitation program, primarily focusing on physical therapy, is critical for regaining knee strength, flexibility, and overall function. This procedure is distinguished from revision knee arthroplasty, which involves replacing existing prosthetic components.

Clinical Indications

  • Severe, debilitating knee pain limiting daily activities (e.g., walking, climbing stairs, standing) unresponsive to conservative management.
  • Failure of non-surgical treatments including medications, injections (corticosteroids, hyaluronic acid), physical therapy, and bracing.
  • Radiographic evidence of severe osteoarthritis (primary, secondary, or post-traumatic), rheumatoid arthritis, or other inflammatory arthropathies.
  • Significant knee deformity such as varus (bowleg) or valgus (knock-knee) requiring surgical correction.
  • Marked stiffness or loss of knee range of motion significantly impacting quality of life.
  • Avascular necrosis (osteonecrosis) of the femoral condyles or tibial plateau leading to joint destruction.
  • Bone tumors affecting the knee joint necessitating resection and subsequent reconstruction.

Procedure Steps

  1. Patient positioning (supine) and administration of general or regional anesthesia.
  2. Sterile preparation and draping of the operative leg.
  3. Creation of a longitudinal anterior knee incision (typically medial parapatellar approach).
  4. Eversion of the patella and exposure of the femoral condyles and tibial plateau.
  5. Precise bony resections of the distal femur and proximal tibia using cutting guides to prepare the surfaces for prosthetic components and ensure correct alignment.
  6. Preparation of the posterior patella surface if patellar resurfacing is indicated.
  7. Placement of trial components to assess fit, stability, and range of motion, with necessary adjustments.
  8. Removal of trial components, thorough cleaning and drying of bone surfaces.
  9. Application of bone cement and insertion of definitive femoral, tibial, and patellar components (if used).
  10. Insertion of the polyethylene bearing insert into the tibial tray.
  11. Irrigation of the joint and meticulous closure of the joint capsule, retinaculum, subcutaneous tissues, and skin.
  12. Application of sterile dressings and often a drain.

Coding Guidelines

  • CPT 27447 specifically describes a *primary* total knee arthroplasty and should not be used for revision procedures (see 27487 or 27488).
  • This code encompasses the implantation of femoral, tibial, and patellar components, including any necessary resurfacing of the patella during the same surgical encounter.
  • Routine procedures such as diagnostic arthroscopy, meniscectomy, or synovectomy performed concurrently with 27447 are generally considered inclusive components and are not separately billable per NCCI edits.
  • For bilateral total knee arthroplasty performed during the same operative session, report 27447 with modifier 50. Alternatively, some payers may prefer reporting 27447 with modifier RT and 27447 with modifier LT.
  • Do not use 27447 for unicompartmental (partial) knee arthroplasty; instead, refer to codes like 27446 (medial or lateral compartment) or 27445 (patellofemoral compartment).

Associated ICD-10 Codes