CPT Code Overview

CPT 29876 describes a surgical arthroscopy of the knee for a major synovectomy involving two or more compartments. This procedure falls within orthopedic surgery and addresses intra-articular disease processes requiring debridement or removal of inflamed synovial tissue across multiple knee compartments. Typical sites of service for CPT 29876 are facility settings, including outpatient hospital (POS 19 or 22) and ambulatory surgical centers (POS 24).

Clinical Context

A 58-year-old patient presents with progressive knee pain, mechanical symptoms, and reduced function despite conservative management. Examination and imaging confirm multi-compartment intra-articular pathology (e.g., synovial hypertrophy and inflammatory synovitis) consistent with osteoarthritis and/or chronic instability. The orthopedic surgeon schedules an outpatient arthroscopic procedure for a major synovectomy of two or more compartments of the knee to remove inflamed synovium, improve joint mechanics, and obtain tissue for pathology if indicated. The procedure is performed in an ambulatory surgical center or outpatient hospital setting with standard preoperative evaluation, regional or general anesthesia, intraoperative arthroscopic assessment of all compartments, synovial resection in the affected compartments, hemostasis, and standard postoperative recovery and discharge instructions.

Coding Specifications

• Modifier RT: Applied when the procedure is performed on the right knee.

• Modifier LT: Applied when the procedure is performed on the left knee.

• Modifier 59: Applied to indicate a distinct procedural service when the synovectomy is separate and distinct from another procedure performed at the same session (use when documentation supports separate anatomical site or separate session component).

• Modifier 51: Applied when multiple procedures are submitted on the same day; used for reporting multiple CPT codes in the same encounter per payer policy.

• Provider Taxonomies:

Related Diagnoses

• M17.11 — Unilateral primary osteoarthritis, right knee

  This diagnosis indicates degenerative joint disease in the right knee, which can produce synovial inflammation and mechanical symptoms leading to a synovectomy.

• M17.12 — Unilateral primary osteoarthritis, left knee

  This diagnosis indicates degenerative joint disease in the left knee and is clinically relevant when synovial proliferation or symptomatic inflammation requires arthroscopic synovectomy.

• M23.50 — Chronic instability of knee, unspecified knee

  Chronic instability can be associated with recurrent intra-articular synovial irritation or hypertrophy; synovectomy may be performed during arthroscopy to address symptomatic synovitis.

• M25.561 — Pain in right knee

  Symptomatic knee pain in the right knee is a common presenting complaint that may lead to diagnostic and therapeutic arthroscopy with synovectomy when conservative care fails.

• M25.562 — Pain in left knee

  Symptomatic knee pain in the left knee similarly correlates with indications for arthroscopic assessment and possible synovectomy.

Related CPT Codes

• 29880: Typically performed when a meniscal tear is addressed during the same arthroscopic session. This code may be reported with 29876 when documentation supports both a major synovectomy and a meniscectomy; payer guidelines on multiple arthroscopic procedures should be followed.

• 29877: Represents chondroplasty or articular cartilage shaving and can be performed in conjunction with 29876 when cartilage lesions are debrided during the same arthroscopy. Documentation should support distinct work for each procedure.

• Common use patterns: 29880 and 29877 are commonly performed in the same operative session as 29876 when intracompartmental pathology includes meniscal tears or articular cartilage damage; selection depends on intraoperative findings and documented procedures.

Medicare mean rates for CPT 29876 sit below the commercial aggregate (BUCA) mean, with Medicare at $627.05 versus BUCA at $887.65. This places Medicare nearer to the lower end of the national payer distribution while the commercial aggregated mean (BUCA) is substantially higher.

Dispersion measured as the interquartile range (P75 − P25) varies across payers. UnitedHealth Group shows the widest spread (1,427.00 − 739.50 = $687.50), indicating the largest middle-50% variability. Blue Cross Blue Shield and Cigna also show wide dispersion ($398.51 and $629.00 respectively), while Medicare is the tightest ($56.00) and Aetna is relatively tight ($382.00) among the commercial payers. The table and chart below present the full breakdown.