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CurrentAetnaPolicy 0660

Knee Arthroplasty

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Defines Aetna medical necessity criteria for total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), revision/replacement of TKA, prophylactic tranexamic acid use, and lists procedures considered experimental/investigational; includes applicable CPT/HCPCS/ICD-10 codes and related documentation expectations for conservative therapy.

Policy Summary

PayerAetna

PolicyKnee Arthroplasty

Policy CodePolicy 0660

Change TypeNo material change

Effective DateMay 2, 2003

Last ReviewNov 20, 2023

Next Review DateJul 12, 2024

Key ActionMedical record must clearly document history of unsuccessful conservative therapy (duration 12 or 24 weeks depending on age/BMI) including PT notes or claims history showing at least half of therapy was formal in-person physical therapy.

SourceLink

POLICY UPDATE CHANGES

No material clinical/coverage changes — has_material_change=false in source.

3Main Covered Procedures (TKA, UKA, Revision TKA)

8Absolute Contraindications Listed

9Experimental/Investigational Items Listed

multipleEvidence Items Summarized

variableEvidence quality / outcomes mixed

Coverage Summary

Scope: Defines Aetna medical necessity criteria for total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), revision/replacement of TKA, prophylactic tranexamic acid use, and lists procedures considered experimental/investigational. Coverage stance: mixed — main procedures (TKA, UKA, revision TKA) are covered when selection criteria are met, while several technologies and implants are listed as experimental/investigational (not covered). Effective date: 2003-05-02; Last review: 2023-11-20; Next review: 2024-07-12.

Surface operational thresholds and quick facts

Conservative therapy durationAt least 12 weeks (or at least 24 weeks for persons with a relative contraindication)

Physical therapy proportionAt least half of conservative therapy must be formal in‑person physical therapy (documented PT notes or claims)

UKA flexion thresholdPatient’s knee arc of motion not limited to 90 degrees or less (i.e., >90° required)

Varus/Valgus deformity limits for UKAVarus deformity >15° (medial UKA) or valgus deformity >20° (lateral UKA) are contraindications

Policy Summary

PayerAetna

PolicyKnee Arthroplasty

Policy CodePolicy 0660

Change TypeNo material change

Effective DateMay 2, 2003

Last ReviewNov 20, 2023

Next Review DateJul 12, 2024

SourceLink

On This Page

Total Knee Arthroplasty (TKA) — Medical Necessity Criteria

Total Knee Arthroplasty - Medically Necessary

Covered when ALL of the following are met:

ALL of the following

Member is an adult and the prosthesis is FDA-approved.
Member has advanced joint disease demonstrated by pain and functional disability that interferes with activities of daily living (ADLs) from injury due to osteoarthritis, rheumatoid arthritis, avascular necrosis, or post-traumatic arthritis of the knee joint.
Limited range of motion, crepitus, or effusion or swelling of the knee joint on physical examination.
AND
- Radiographic evidence of moderate/severe osteoarthritis of the knee joint (Kellgren-Lawrence Grade 3 or 4).
- Radiographic evidence of avascular necrosis (osteonecrosis) of tibial or femoral condyle.
- Radiographic evidence of rheumatoid arthritis (joint space narrowing).
History of unsuccessful conservative therapy (non-surgical medical management; 12 or 24 weeks depending on age/BMI) that is clearly documented in the medical record, unless conservative therapy is contraindicated. If conservative therapy is not appropriate (for example severe osteoarthritis with bone-on-bone articulation in the weight-bearing portion of the joint, severe angular deformity, avascular necrosis with collapse of tibial or femoral condyle, or progressive flexion contracture), the medical record must clearly document why such approach is not reasonable.
See Conservative Therapy Requirements group for required therapies and documentation.
OR
- Failure of a previous osteotomy with pain interfering with ADLs.
- Distal femur or proximal tibia malunion by imaging with pain interfering with ADLs.
- Distal femur or proximal tibia fracture or nonunion.
- Malignancy of the distal femur, proximal tibia, knee joint or adjacent soft tissues by imaging.
- Failure of previous unicompartmental knee replacement with pain interfering with ADLs.

Conservative Therapy Requirements

Conservative (non-surgical) therapy must be documented in the medical record for at least 12 weeks (or at least 24 weeks for persons with a relative contraindication such as morbid obesity [BMI >40] or age <50), unless contraindicated. At least half of the conservative therapy should consist of formal supervised (in-person) physical therapy within the past year. Physical therapy must be confirmed by PT notes or member claims history.

ALL of the following

Anti-inflammatory medications or analgesics.
Flexibility and muscle strengthening exercises.
Activity modification.
Supervised physical therapy (in-person rather than home or virtual physical therapy); ADLs remain diminished despite completing a plan of care.
PT must be documented in chart or claims history.
Assistive device and injections

Absolute Contraindications to Total Joint Replacement - Not Medically Necessary

Total joint replacement is considered not medically necessary when ANY of the following absolute contraindications are present:

ANY of the following

Active infection of the joint or active systemic bacteremia that has not been totally eradicated.
Active skin infection (exception: recurrent cutaneous staph infections) or open wound within the planned surgical site of the knee.
Vascular insufficiency, significant muscular atrophy of the leg, or neuromuscular disease severe enough to compromise implant stability or postoperative recovery, or quadriplegia.
Osseous abnormalities that cannot be optimally managed and which would increase the likelihood of a poor surgical outcome (for example inadequate bone stock to support the implant).
Allergy to components of the implant (e.g., cobalt, chromium or alumina).

Relative Contraindications - Operational Notes

Relative contraindications should be considered operational notes; members with these should exhaust nonsurgical options and documentation of extended conservative therapy (24 weeks) is required. The risk/benefit should be documented in the medical record.

ANY of the following

Morbid obesity (BMI greater than 40).
Require at least 24 weeks of conservative therapy unless otherwise documented why not appropriate.
Age less than 50 years.
Require at least 24 weeks of conservative therapy unless otherwise documented why not appropriate.

Revision / Replacement of TKA — Medical Necessity Criteria

Revision or Replacement of Total Knee Arthroplasty - Medically Necessary

Revision/replacement considered medically necessary when accompanied by pain and functional disability (interference with ADLs) and ALL applicable criteria are met:

ALL of the following

Indications (ANY of the following)
- Aseptic loosening of one or more prosthetic components confirmed by imaging
- Fracture of one or more components of the prosthesis or worn or dislocated plastic insert confirmed by imaging
- Confirmed periprosthetic infection by gram stain and culture
- Periprosthetic fracture of distal femur, proximal tibia or patella confirmed by imaging
- Progressive or substantial periprosthetic bone loss confirmed by imaging
- Bearing surface wear leading to symptomatic synovitis
- Implant or knee malalignment (valgus/varus or flexion/extension greater than 15 degrees)
- Knee arthrofibrosis
- Instability or dislocation of the TKA
- Extensor mechanism instability
- Upon individual case review, persistent knee pain of unknown etiology not responsive to a period of non-surgical care for 6 months
Member must NOT have ANY of the following contraindications to revision surgery
- Persistent infection
- Poor bone quality
- Highly limited quadriceps or extensor function
- Poor skin coverage
- Poor vascular status

Unicompartmental Knee Arthroplasty (UKA) — Medical Necessity Criteria

Unicompartmental Knee Arthroplasty (UKA) - Medically Necessary

Covered when ALL of the following are met for members with advanced osteoarthritis or post-traumatic arthritis affecting only a single compartment:

ALL of the following

Pain and functional disability that interferes with ADLs due to osteoarthritis or post-traumatic arthritis of the knee joint
Limited range of motion, crepitus, or effusion or swelling of knee joint on physical examination
Intact, stable ligaments, in particular the anterior cruciate ligament (ACL)
Patient’s knee arc of motion (full extension to full flexion) is not limited to 90 degrees or less
Radiographic evidence of moderate/severe osteoarthritis (Kellgren-Lawrence Grade 3 or 4) affecting only a single compartment (medial, lateral or patellofemoral)
History of unsuccessful conservative therapy (12 or 24 weeks depending on age/BMI) clearly addressed in the medical record with at least half of therapy being formal in-person physical therapy
None of the following contraindications to UKA
- Previous proximal tibial osteotomy or distal femoral osteotomy
- Tibial or femoral shaft deformity
- Radiographic evidence of medial or lateral subluxation
- Flexion contracture greater than 15 degrees
- Varus deformity greater than 15 degrees (medial UKA) or valgus deformity greater than 20 degrees (lateral UKA)
- Inflammatory or crystalline arthropathy
- Subchondral bone loss due to large subchondral cysts or extensive focal osteonecrosis
None of the following absolute contraindications to joint replacement
- Active infection of the joint or active systemic bacteremia that has not been totally eradicated
- Active skin infection or open wound within the planned surgical site of the knee
- Vascular insufficiency, significant muscular atrophy, or neuromuscular disease severe enough to compromise implant stability or post-operative recovery or quadriplegia
- Osseous abnormalities that cannot be optimally managed and which would increase likelihood of poor surgical outcome
- Allergy to components of the implant (e.g., cobalt, chromium or alumina)

Experimental & Investigational Procedures (Not Covered)

Experimental and Investigational (Not Covered)

The following are considered experimental and investigational because effectiveness has not been established:

ANY of the following

Bacteriophage therapy for treatment of knee arthroplasty-related peri-prosthetic joint infection
Bicompartmental, staged bicompartmental, and bi-unicompartmental knee arthroplasty for osteoarthritis of the knee and all other indications
Custom instrumentation for the procedure including cutting blocks
Customized total or partial knee implant
Prophylactic radiation therapy following total knee arthroplasty
UniSpacer interpositional spacer for treatment of osteoarthritis affecting the medial compartment of the knee
Computer-assisted musculoskeletal surgical navigation (e.g., MAKOplasty) - considered experimental and investigational for knee arthroplasty
Robotic assistance is considered integral to the primary procedure and not separately reimbursed
Pre-operative advanced imaging where required for any experimental and investigational procedure (e.g., required for computer-assisted surgical navigation, robotic-assisted navigation, or for customized patient implants/instrumentation)

Summary: These items are considered experimental and investigational because effectiveness has not been established and evidence is insufficient, per the policy’s Evidence Summary and Experimental/Investigational list.

Evidence Summary and Coverage Considerations

Evidence summary and implicit coverage considerations: Available evidence is insufficient to support routine use of bicompartmental/bi-unicompartmental implants as alternatives to TKA, with mixed short-term functional findings but reports of higher revision/failure for some designs. Patient-specific instrumentation (PSI) / customized implants (CIM) and patient-specific cutting blocks show some improvements in alignment or perioperative metrics in small or selected studies, but long-term clinical benefit and robust outcome improvements are unproven. Patellofemoral arthroplasty (PFA) can yield faster early recovery and some short-term PRO advantages versus TKA in selected patients, but may have higher revision rates in some series. Robotic/navigation techniques reduce alignment outliers and variance in component positioning, yet no consistent long-term clinical outcome or survivorship advantage has been demonstrated.

Study / Source	Key Finding	Implication for Coverage
Unispacer — Bailie et al. (2008)	Prospective 18‑patient series: 44% required revision within 2 years	High early revision rate; UniSpacer considered investigational/not established; supports non‑coverage
Bi‑UKR vs computer‑assisted TKR — Confalonieri/Framed 48‑month matched study	No difference in Knee Society scores; Bi‑UKR had better WOMAC Function/Stiffness and shorter hospital stay for Bi‑UKR	Some short‑term functional benefit in selected series but insufficient long‑term evidence; bicompartmental approaches remain experimental
Parratte long‑term bicompartmental series (Parratte et al.)	At mean 12‑17 years: prosthesis survivorship 78% for bicompartmental UKA vs 54% for medial UKA/PFA; higher revision vs TKA noted	Long‑term survivorship variable with higher revision rates in some series; argues caution and limited coverage until better evidence
Odgaard RCT (PFA vs TKA, 2018)	PFA: faster early recovery and better AUC for several PROs up to 2 years; no difference in complications over 2 years	PFA may be reasonable in appropriately selected isolated patellofemoral disease; supports conditional coverage for PFA in selected patients
Bunyoz systematic review (PFA vs TKA)	Second‑generation PFA and TKA have similar PROMs; PFA revision rate higher (8.4% vs 1.3%)	Short‑term PRO parity but higher revision risk for PFA — selection and counseling important; not broadly preferred over TKA
Journey‑Deuce bicompartmental implant — Dudhniwala et al. (2016)	Cohort (n=15): early aseptic loosening and 60% revision at minimum 54 months; implantation ceased at institution	Device‑specific high early failure supports classification as experimental/investigational and non‑coverage for that implant
PSI / Navigation meta‑analyses (Huijbregts 2016b; Thienpont 2017; Bouche network meta‑analysis)	PSI yields small radiographic differences, mixed tibial outlier effects, minimal clinical benefit; navigation reduces HKA outliers vs PSI/standard (~10% fewer) but no consistent PRO improvement	Robotic/navigation/PSI improve some radiographic accuracy but lack consistent clinically meaningful benefit — considered experimental/investigational or integral (not separately reimbursed)
CIM observational / single‑center cohorts (Culler 2017; Schwarzkopf 2015; Shroeder 2019)	Reports of lower transfusion/adverse events, reduced LOS, high early survivorship in small series; limited generalizability	Promising perioperative/efficiency signals but insufficient high‑quality long‑term comparative evidence — coverage limited to FDA‑approved devices and selection criteria; CIM remains conditional
Economic analyses / simulation (O'Connor 2019; Namin 2019)	Medicare episodes: customized cohort lower average episode spending ($18,585 vs $20,280); simulation projects potential large savings with broad CIM adoption but relies on assumptions	Economic models suggest potential savings but do not replace clinical effectiveness evidence; payers may require stronger clinical data before broad coverage expansion
Femoral overhang — Mahoney & Kinsey (2010)	≥3 mm femoral overhang in ≥1 zone occurred in 40% men, 68% women; associated OR 1.9 for increased knee pain at 2 years	Implant fit matters; supports interest in patient‑specific or better sizing but does not by itself mandate coverage of CIM/PSI
Robotic arm / MAKO and long‑term RCT (Kim et al. long‑term RCT) and systematic reviews	Robotic assistance reduces alignment variance and outliers but long‑term RCT (13‑yr) showed no difference in function, survivorship, or complications; systematic reviews find better radiographic accuracy but no meaningful clinical benefit	Robotic techniques improve precision yet lack demonstrated long‑term clinical/survivorship benefit — considered integral/experimental and not separately reimbursed
Meta‑analyses of PSI trials (Rudran 2022; Hinloopen 2023; Russell 2014)	Mostly no clinical differences in PROs; occasional small statistically significant changes below MCID at 2 years; mixed alignment outcomes	PSI/PSCG/CCB not shown to provide clinically meaningful advantages to justify routine separate reimbursement; considered experimental/adjuvant
Tammachote RCT (CCB vs conventional, 2018)	No improvement in alignment or functional outcomes; operative time reduced by 11 mins	CCB may reduce OR time but lacks evidence of clinical benefit — experimental adjunct
ConforMIS / CIM cohort and kinematics (Zeller 2017; Shroeder 2019)	CIM associated with more normal kinematics, high satisfaction, 100% survivorship at ~1.9 yrs in small cohort; MUA rates comparable to literature	Short‑term favorable signals exist but long‑term comparative data limited; selective use may be considered where criteria met; broader coverage contingent on evidence
Ceramic femoral prosthesis long‑term (Nakamura 2017)	507 TKAs: 15‑year survivorship 94% (revision/radiographic failure) and 96.2% (revision any component)	Long‑term data support certain alternative materials/devices when FDA‑approved; coverage aligned with device approval and selection criteria
MAKO/robotic observational UKA series (Deese 2018) and systematic reviews (Ruangsomboo 2023)	Robotic‑assisted UKA shows good early PROMs and accuracy; meta‑analysis: improved radiologic accuracy but little/no difference in PROs or survivorship at long‑term	Robotics may improve technical accuracy but lacks proven clinically meaningful long‑term outcome advantages — treated as integral/experimental adjunct not separately reimbursed
Callahan meta‑analysis (1995) & registry/cohort summaries (Wilson 2019) comparing UKA vs TKA	UKA and TKA have similar pain/function in many studies; UKA often shorter LOS and faster recovery but higher revision rates at 5–10 years	Supports coverage of UKA in appropriately selected patients per criteria; tradeoffs between faster recovery and higher revision risk must be considered
Parratte et al. (2010) & long‑term bicompartmental review	Bicompartmental arthroplasty gives short‑term improvement but long‑term durability not well documented; some implant designs had early failures and withdrawal	Evidence insufficient to support routine coverage of bicompartmental/bi‑UKA; considered experimental/investigational
Network/meta‑analysis (Bouche 2020) comparing navigation, PSI, robotics, standard guides	Navigation reduced HKA outliers vs PSI/standard (~10% fewer), but no differences in KSS/WOMAC at 6 months; other technologies showed mixed radiographic benefits without PRO improvement	Radiographic improvements alone are insufficient to justify routine separate reimbursement of navigation/PSI/robotics; considered experimental/integral adjuncts

Coding

TKA - Covered if selection criteria are metCPTCovered

27447

Arthroplasty, knee, condyle and plateau; medial AND lateral compartments with or without patella resurfacing (total knee arthroplasty)

TKA - Not covered (separately) / Experimental adjunctsCPTNot Covered

0396T	Intra-operative use of kinetic balance sensor for implant stability during knee replacement arthroplasty (List separately)
0054T	Computer-assisted musculoskeletal surgical navigation, image-guidance based on fluoroscopic images
0055T	Computer-assisted musculoskeletal surgical navigation, image-guidance based on CT/MRI images
20985	Computer-assisted surgical navigation procedure for musculoskeletal procedures, image-less
77401	Radiation treatment delivery (listed range 77401-77412) [following total knee arthroplasty]

Related CPT (other procedures)CPT

27440	Arthroplasty, knee, tibial plateau
27441	with debridement and partial synovectomy
27442	Arthroplasty, femoral condyles or tibial plateau(s), knee
27443	with debridement and partial synovectomy
27445	Arthroplasty, knee, hinge prosthesis (eg, Walldius type)
73700	Computed tomography, lower extremity (range 73700-73702 listed)
73718	Magnetic resonance imaging, any joint of lower extremity (range 73718-73723 listed)

Revision TKA - Covered if selection criteria are metCPTCovered

27486	Revision of total knee arthroplasty, with or without allograft
27487	Revision of total knee arthroplasty, with or without allograft (listed range 27486-27487)
27488	Removal of prosthesis, including total knee prosthesis, methylmethacrylate with or without insertion of spacer, knee

Revision TKA - Not covered (separately) / Experimental adjunctsCPTNot Covered

0396T	Intra-operative kinetic balance sensor (list separately)
0054T	Computer-assisted navigation (fluoroscopic)
0055T	Computer-assisted navigation (CT/MRI)
20985	Computer-assisted surgical navigation, image-less
77401	Radiation treatment delivery (77401-77412) [following total knee arthroplasty]

HCPCS - Covered if selection criteria are metHCPCSCovered

C1776

Joint device (implantable) [FDA approved device]

HCPCS - Not covered (customized devices / robotics)HCPCSNot Covered

S2900	Surgical techniques requiring use of robotic surgical system (list separately)
C1776	Joint device (implantable) [not covered for customized total knee implant]

Unicompartmental Knee Arthroplasty - Covered if selection criteria are metCPTCovered

27437	Arthroplasty, patella; without prosthesis
27438	Arthroplasty, patella; with prosthesis
27446	Arthroplasty, knee, condyle and plateau; medial OR lateral compartment

ICD-10 - Covered diagnosesICD-10Covered

M17.0-M17.9	Osteoarthritis of knee [with radiographic evidence]
M87.061-M87.066	Idiopathic aseptic necrosis of tibia and fibula
M89.9	Disorder of bone, unspecified [confirmed by imaging]
M94.9	Disorder of cartilage, unspecified [confirmed by imaging]
M97.11x+-M97.12x+	Periprosthetic fracture around internal prosthetic, knee joint [confirmed by imaging]
T84.012+-T84.013+	Broken internal knee prosthesis [confirmed by imaging]
T84.022+-T84.023+	Instability of internal knee prosthesis
T84.032+-T84.033+	Mechanical loosening of prosthetic joint [confirmed by imaging]
T84.062+-T84.063+	Wear of articular bearing surface of internal prosthetic knee joint [confirmed by imaging]
T84.092+-T84.093+	Other mechanical complication of internal knee prosthesis [confirmed by imaging]

1–10 of 11

1/2

ICD-10 - Not covered / Exclusion diagnoses (Not eligible for joint replacement)ICD-10Not Covered

A00.0-B99.9	Infectious and parasitic diseases
I87.2	Venous insufficiency (chronic) (peripheral)
L08.0, L08.81, L88	Pyoderma / related skin conditions
M00.861-M00.869	Arthritis due to other bacteria, knee
M01.X61-M01.X69	Direct infection of knee in infectious and parasitic diseases classified elsewhere
M62.551-M62.559	Muscle wasting and atrophy, thigh [muscle atrophy of the leg]
M62.561-M62.569	Muscle wasting and atrophy, lower leg [muscle atrophy of the leg]
M89.711-M89.79	Major osseous defect [osseous abnormalities]
S81.001+-S81.859	Open wound of knee and lower leg
T78.40x+	Allergy, unspecified, NEC [allergy to components of the implant]

Codes associated with UniSpacer / Bicompartmental / Custom implantsmixedNot Covered

No specific CPT	UniSpacer interpositional spacer - no specific code; considered experimental/investigational
No specific CPT	Bicompartmental, bi-unicompartmental knee and staged bicompartmental arthroplasty - no specific code; considered experimental/investigational
No specific CPT	Custom instrumentation for the procedure including cutting block - considered experimental/investigational

Provider Actions and Authorization Requirements

Documentation Required

Document conservative therapy

Medical record must clearly document history of unsuccessful conservative therapy including duration and confirmation of PT. At least 12 weeks (or at least 24 weeks for persons with a relative contraindication) of non-surgical treatment must be documented, with at least half of the necessary conservative therapy consisting of formal in‑person physical therapy. Physical therapy should be confirmed by actual PT notes or member claims history.

Duration: ≥12 weeks (or ≥24 weeks if relative contraindication)
Confirm at least half of therapy was formal in‑person physical therapy
Provide PT notes or claims history documenting supervised PT

Prior Authorization

Medical necessity review for arthroplasty

Procedures (TKA, UKA, revisions) are covered only when the policy selection criteria are met and relevant imaging/confirmation is provided. Prior authorization/medical record should include radiographic evidence or imaging confirmation of indicated pathology (e.g., K-L Grade 3–4 osteoarthritis, avascular necrosis, imaging confirming prosthetic complication) to support medical necessity review for arthroplasty.

Include radiographs showing Kellgren‑Lawrence Grade 3 or 4 when applicable
Provide imaging confirming avascular necrosis, prosthetic loosening, fracture, or other listed indications
Ensure documentation addresses the applicable inclusion criteria in policy

Documentation Required

Contraindication documentation

If conservative therapy is inappropriate (for example: severe bone-on-bone osteoarthritis in the weight-bearing portion, severe angular deformity, avascular necrosis with collapse, or progressive flexion contracture), the medical record must document why conservative management is not reasonable for the member.

State specific contraindication(s) that make conservative therapy unreasonable
Describe clinical/imaging findings that support exemption from conservative therapy

Billing Rule

Robotic/navigation/kinetic sensor not separately reimbursed

Intra-operative kinetic balance sensors and robotic/computer-assisted navigation are considered incidental/integral or experimental and are not eligible for separate reimbursement; do not bill these codes separately in addition to the primary arthroplasty procedure.

Documentation Required

Patient selection documentation for bicompartmental procedures

When considering bicompartmental or bi‑UKA approaches, document patient-specific factors that align with the selection criteria and the patient characteristics reported in favorable series. Include preoperative clinical and imaging findings that match study-based inclusion parameters.

Asymptomatic patellofemoral joint (when applicable)
Varus deformity less than 8°
BMI < 34 (per reported series)
Intact ACL and absence of flexion deformity
Pre-op range of motion ≥110°

Documentation Required

Document indications for patellofemoral arthroplasty

For patellofemoral arthroplasty (PFA) candidacy, document isolated patellofemoral osteoarthritis with debilitating symptoms and absence of tibiofemoral disease as reflected in randomized and comparative studies.

Confirm isolated PFOA on imaging and clinical exam
Document debilitating symptoms and failure of appropriate conservative care
Reference randomized trial eligibility (isolated patellofemoral disease) when applicable

Definitions

Term	Definition
Relative contraindication	Conditions such as morbid obesity (BMI > 40) or age <50 that require exhaustion of nonsurgical options and may extend conservative therapy to 24 weeks
Absolute contraindication	Conditions (e.g., active joint infection, inadequate bone stock, allergy to implant components) that render total joint replacement not medically necessary
Bi-UKR / BKA / Bi-UKA	Bicompartmental knee arthroplasty — replacement/resurfacing of two compartments (eg. medial or lateral tibiofemoral plus patellofemoral), aiming to preserve ligaments and bone
PFA	Patellofemoral arthroplasty — partial knee replacement isolated to the patellofemoral compartment
UKA	Unicompartmental knee arthroplasty — replacement of a single tibiofemoral compartment
TKA	Total knee arthroplasty — replacement of the entire knee joint
CIM	Customized individually made implant — patient-specific total knee implant produced from preoperative imaging
PSI	Patient-specific implant/instrumentation — implants or cutting guides customized to patient anatomy using preoperative CT or MRI
CCB	Customized cutting block — patient‑specific cutting guide made from preoperative imaging to assist bone resections
MUA	Manipulation under anesthesia — procedure for treating post‑operative arthrofibrosis/limited ROM after knee arthroplasty
OTS	Off‑the‑shelf implants — standard, non‑customized knee implant systems
HO	Heterotopic ossification — abnormal bone formation in soft tissues after surgery
HKA	Hip‑Knee‑Ankle angle — measure of lower‑limb mechanical alignment used to assess coronal alignment; outliers often defined as >±3° from neutral
Outlier	Deviation greater than 3° from the planned/mechanical axis/alignment target (commonly used threshold for malalignment)
PSI/PSCG	Patient‑specific implants / patient‑specific cutting guides — customized guides or implants derived from axial imaging to individualize sizing and cuts
CI	Conventional instrumentation — standard intra‑medullary or extra‑medullary guides used for component alignment
Bi‑UKA (staged) / staged bicompartmental	Staged bi‑UKA refers to adding a second UKA to a knee previously treated with a UKA to address progression in another compartment
Customization (economic/evidence note)	Customized implants/instruments may reduce trays/LOS or transfusion in select observational studies and may show reduced episode spending in administrative analyses, but high‑quality long‑term RCT evidence is limited
UniSpacer	Mobile metallic interpositional spacer for isolated medial compartment OA; published small series report high early revision rates and insufficient evidence to support widespread use

Knee Arthroplasty

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Coverage Summary

Total Knee Arthroplasty (TKA) — Medical Necessity Criteria

Revision / Replacement of TKA — Medical Necessity Criteria

Unicompartmental Knee Arthroplasty (UKA) — Medical Necessity Criteria

Prophylactic Tranexamic Acid

Experimental & Investigational Procedures (Not Covered)

Evidence Summary and Coverage Considerations

Coding

Provider Actions and Authorization Requirements

Definitions

Evidence Metrics & Selected Study Outcomes

Revision History