Unicompartmental Knee Replacement Surgery
DESCRIPTIONWhile osteoarthritis of the knee typically involves both medial and lateral components, some patients may have signs or symptoms confined to only one compartment, often as a result of specific injury. Initial treatment of uni- and bicompartmental disease is similar, i.e., analgesics, viscosupplementation, and arthroscopic debridement. (see policy No. 2.01.31) When patients fail to respond to these more conservative therapies, surgical interventions may be indicated.
Older patients with arthritis typically consider total knee replacement, but may be considered for unicondylar knee arthroplasty. The metal-to-plastic unicondylar prosthesis has both tibial and femoral components, but leaves intact both cruciate ligaments, the patellofemoral joint and the opposite compartment, thus preserving nearly normal knee kinematics. Unicompartmental arthroplasties are typically performed in patients with isolated medial arthritis who are older than 60 years, have a low level of physical activity and weigh less than 180 lbs.
Younger patients are usually not considered ideal candidates for total knee arthroplasty since they would be expected to need at least one additional total knee replacement in their lifetimes. The preferred option for young patients with unicompartmental disease is high tibial osteotomy. Those with medial compartment disease may also be candidates for unicompartmental arthroplasty or for fixed metallic hemiarthroplasty. MacIntosh and McKeever hemiarthroplasty devices were used primarily between 1950 and 1970, but their use has decreased with the refinement of total knee arthroplasty procedures. These devices require bone cuts that might complicate future arthroplasty procedures.
Metallic interpositional unicondylar spacers have been developed as possible alternatives to osteotomy or unicompartmental arthroplasty. These devices do not require any bone resection or mechanical fixation for proper function. Following debridement and resection of the meniscus, the device is fit to the joint space above the affected tibial plateau and held in place by its geometry, ligament tension and the surrounding soft tissue structures. The uncemented implant adapts to the kinematics of the knee, with a smooth metallic curved surface against which the femur articulates. Preservation of bone is important for the use of interpositional spacers as a bridge procedure in active young adults or for overweight patients who would not be candidates for unicompartmental arthroplasty.
In 2001, a cobalt alloy device, referred to as a "unicondylar interpositional spacer" or "UniSpacer" received clearance for marketing through a U.S. Food and Drug Administration (FDA) 510(k) process as an interpositional arthroplasty device, listing the MacIntosh and McKeever prostheses as predicate devices. The FDA clearance for the UniSpacer device is for "moderate degeneration of the medial compartment of the knee (grade III-IV chondromalacia) with not more than minimal degeneration (grade I-II chondromalacia, no loss of joint space) in the lateral condyle and patellofemoral compartments." The Orthoglide Medical Knee Implant, which received 510(k) approval in 2006, is also indicated for "uncemented use in the treatment of moderate degeneration of the medial compartment of the knee," but for grade II-IV chondromalacia.
Two other interpositional devices have received 510(k) approval, the Oti Unicondular Interpositional Spacer Osteoimplant (2002) and the Knee Interpositional Mini-Repair System (2003), listing the UniSpacer as a predicate device. The Knee Interpositional Mini-Repair System is a patient-specific design, with specifications taken from magnetic resonance scans. These devices are indicated for the uncemented treatment of medial and/or lateral tibial articulating surfaces of the osteoarthritic knee with grade II-IV chondromalacia.
Unicompartmental knee replacement in patients who are considered suitable candidates for surgical treatment of osteoarthritis, when damage to the joint is completely or almost completely confined to the medial or the lateral compartment of the knee is medically necessary.
Unicompartmental knee replacement in patients with osteoarthritis that involves more than one compartment of the knee, or for patients with any of the following contraindications in the affected knee is considered investigational:
Unicompartmental knee replacement in patients with rheumatoid arthritis is considered investigational.
Investigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY3/2003: Approved by Medical Policy Advisory Committee (MPAC)
3/10/2004: Code Reference section updated, CPT code 27447 deleted, ICD-9 procedure codes 81.54, 81.55 deleted, ICD-9 diagnosis codes 717.0-717.9, 718.86, 733.40-733.49, 733.92, 733.99, 836.0-836.69 deleted
11/13/2006: Policy reviewed, no changes
03/08/2013: Policy reviewed; no changes.
Hayes Medical Technology Directory
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.
The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document.