DRG 470 - Major Joint Replacements or Reattachment of Lower Extremity

Published 03/12/2024

Major joint replacement or reattachment of the lower extremity (DRG 470) is Medicare’s top volume Medicare Severity (MS) – Diagnosis Related Group (DRG)s. Due to the high volume of these claims, CMS has had multiple auditing entities reviewing claims for these MS-DRGs, including the Recovery Auditors, Comprehensive Error Rate Testing (CERT) Contractors, and Medicare Administrative Contractors (MACs), reviewing claims for these MS-DRGs. The findings have demonstrated very high paid claim error rates among both hospital and professional claims associated with major joint replacement surgery.

Top Denials for DRG 470

  • Medical Necessity
  • Insufficient documentation
  • No documentation

The primary reason for these errors is inpatient admission wasn’t medically necessary when the invasive procedure should’ve been billed as an outpatient procedure. CMS removed total knee arthroplasty (TKA) procedures from Medicare’s inpatient-only list (IPO) in January 2018. When deemed necessary the medical record must indicate that inpatient hospital care was medically necessary, reasonable, and appropriate for the diagnosis and condition of the beneficiary at any time during the stay.

To Avoid Denials, Include the Following in the Medical Record:

  • Relevant information addressing coverage criteria related to the beneficiary's episode of care, should be included in the record
  • Correct beneficiary
  • Correct Date of Service
  • History and Physical
  • Physician Progress Notes
  • Description of the pain (onset, duration, character, aggravating, and relieving factors)
  • Pain causing functional disability that interferes with ADLs or pain that is increased with initiation of activities or increases with weight bearing
  • Safety issues (falls, for example)
  • Contraindications to non-surgical treatments
  • Listing, description and outcomes of failed non-surgical treatments, such as:
    • Trial of medications (for example, Nonsteroidal anti-inflammatory drugs (NSAIDs)
    • Weight loss
    • Physical therapy and/or home exercise plans
    • Intra-articular injections
    • Assistive devices (for example, cane, walker, braces (specify type of brace), and orthotics)

Objective Findings to Include in the Physical Examination

  • Any deformity
  • Range of motion
  • Crepitus
  • Effusions
  • Tenderness
  • Gait description (with or without mobility aides)
  • Include any test that were given (plain radiography and pre-operative imaging studies) 

Pre-Operative Documentation Should Include Specific Conditions

  • For patients with significant conditions or comorbidities, the risk/benefit of non-cardiac surgery, such as TKA or THA should be appropriately documented in the medical record
  • Osteoarthritis (mild, moderate, severe)
  • Arthritis of the knee or hip supported by X-ray or MRI and should demonstrate one of the following:
    • Subchondral cysts
    • Subchondral sclerosis
    • Periarticular osteophytes
    • Joint subluxation
    • Joint space narrowing
    • Avascular necrosis
    • Bone on bone articulation
  • Inflammatory arthritis (rheumatoid arthritis, psoriatic arthritis)
  • Failure of previous osteotomy
  • Malignancy of distal femur, proximal tibia, knee joint, soft tissues 
    • Pathology reports and referral from an oncologist
  • Failure of previous unicompartmental knee replacement
  • Avascular necrosis of knee
  • Malignancy of the pelvis or proximal femur or soft tissues of the hip
    • Pathology reports and referral from an oncologist
  • Avascular necrosis of the femoral head
  • Fractures (for example: distal femur, femoral neck, acetabulum)
  • Nonunion, malunion or failure of previous hip fracture surgery
  • Osteonecrosis
  • Laboratory and/or pathology reports
    • If infection involved above reports must be in medical record and all documentation regarding treatment of infection and a physician note indicating that it is appropriate to proceed with surgery

Post-Operative Documentation

  • Operative report for the procedure, including observed pathology
  • Daily progress notes for inpatients
  • Discharge summary, plan and discharge orders


Was this article helpful?