Summary & Overview

CPT 27345: Popliteal (Baker’s) Cyst Excision

CPT code 27345 represents the surgical excision of a popliteal (Baker’s) synovial cyst, a procedure employed to relieve posterior knee pain and restore range of motion when conservative measures fail. This code is clinically significant because Baker’s cysts are common comorbid findings in knee pathology and can affect function, drive episodic care, and lead to outpatient or inpatient surgical episodes. National payers commonly involved in authorization and payment decisions for this procedure include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.

Readers will find a concise clinical and billing-focused overview that explains the procedure context, typical sites of service, and procedural intent. The publication provides benchmarks and payer coverage notes where available, highlights relevant billing considerations for surgical services, and summarizes policy variations and coding guidance impacting utilization and reimbursement nationally. Clinicians and billing professionals will gain clarity on the code’s clinical purpose and the kinds of analyses and policy updates that influence coverage and payment trends. Data not available in the input is noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareCPT 27345popliteal cyst excisionBaker's cyst surgeryorthopedic surgeryknee proceduressurgical billingprocedure codingoutpatient surgeryoperative CPT

Billing Code Overview

CPT code 27345 describes the surgical removal of a synovial (Baker’s) cyst from the popliteal space. This procedure is performed to relieve posterior knee pain and improve range of motion when a cyst is symptomatic or causing mechanical limitation.

Service type: Surgical excision of a popliteal (Baker’s) cyst
Typical site of service: Hospital operating room or outpatient surgical center

Clinical & Coding Specifications

Clinical Context

A typical patient is a 45–70-year-old adult presenting with posterior knee swelling, aching, and limited knee flexion due to a symptomatic popliteal (Baker) cyst. The patient commonly reports activity-related posterior knee pain, morning stiffness, and episodes of cyst fluctuation. Clinical workflow: history and focused musculoskeletal exam demonstrating a palpable fluctuant mass in the popliteal fossa and pain with terminal flexion; point-of-care or diagnostic ultrasound confirms a synovial fluid–filled cyst communicating with the knee joint and may exclude deep venous thrombosis. Conservative management (rest, NSAIDs, aspiration with or without corticosteroid injection, physical therapy) is attempted first. Indications for surgical excision (27345) include recurrent symptomatic cysts causing persistent pain, limited range of motion, neurovascular compression, or cysts that recur after aspiration. Preoperative evaluation includes informed consent, surgical planning (open posterior approach vs arthroscopic-assisted techniques), anesthesia assessment, and appropriate imaging review. Typical site of service is an outpatient ambulatory surgery center or hospital outpatient department under regional or general anesthesia. Postoperative care includes short-term immobilization, analgesia, wound care, and outpatient physical therapy to restore range of motion and calf strength.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased Procedural Services	Use when work or time required is substantially greater than typical for `27345` due to extensive dissection or altered anatomy.
`50`	Bilateral Procedure	Use when bilateral popliteal cyst excisions are performed in the same operative session.
`51`	Multiple Procedures	Use when `27345` is performed with additional distinct surgical procedures during the same operative session.
`52`	Reduced Services	Use when the procedure is partially performed or abbreviated.
`53`	Discontinued Procedure	Use when the procedure is started but terminated for patient-related or intraoperative reasons.
`57`	Decision for Surgery (Not in list)	Data not available in the input.
`59`	Distinct Procedural Service	Use to indicate a separate and distinct procedure when documentation supports that `27345` is independent of other procedures performed same day.
`62`	Two Surgeons	Use when two surgeons from different specialties work together as primary surgeons for technically demanding excision.
`63`	Procedure Performed on Infants Less Than 4 kg (rare)	Use when patient meets criteria — seldom applicable for this adult procedure.
`76`	Repeat Procedure by Same Physician	Use when the same surgeon performs a repeat excision during the postoperative period.
`77`	Repeat Procedure by Another Physician (not in list)	Data not available in the input.
`78`	Unplanned Return to Operating Room	Use when a return to the OR is required for a complication related to the original `27345` during the global period.
`80`	Assistant Surgeon	Use when an assistant surgeon participates and billing requires the assistant surgeon modifier.
`LT`	Left Side	Use to identify laterality when billing for a left popliteal cyst excision.

Taxonomy Code	Specialty	Notes
`207L00000X`	Orthopaedic Surgery	Orthopaedic surgeons commonly perform cyst excision and knee-related procedures.
`207P00000X`	Podiatric Surgery	Podiatric surgeons with specialty training in rearfoot/ankle may perform posterior knee and popliteal procedures when appropriate.
`2080P0207X`	General Surgery	General surgeons with soft-tissue or limb surgery experience may perform cyst excisions in certain settings.
`207K00000X`	Sports Medicine (Orthopaedics)	Sports medicine orthopaedists perform arthroscopic-assisted or open excisions for symptomatic popliteal cysts.
`363L00000X`	Nurse Practitioner	Advanced practice providers may assist in perioperative care but do not bill for the primary surgical CPT when not performing the operation.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`M71.2`	Bakers cyst	Direct diagnosis indicating a popliteal synovial cyst; primary indication for `27345` when symptomatic.
`M17.9`	Knee osteoarthritis, unspecified	Osteoarthritis can increase intra-articular fluid production and lead to cyst formation.
`M25.561`	Pain in right knee	Symptom code often present in patients undergoing cyst excision for pain relief.
`M25.562`	Pain in left knee	Symptom code for left-sided pain associated with a popliteal cyst.
`M65.861`	Other synovitis and tenosynovitis, right knee	Inflammatory synovitis can contribute to cyst development and may be addressed at surgery.
`M65.862`	Other synovitis and tenosynovitis, left knee	Left-sided correlate with clinical relevance to cyst pathophysiology.
`I80.2`	Phlebitis and thrombophlebitis of other deep vessels of lower extremities	Included as a differential to exclude deep venous thrombosis when evaluating popliteal swelling.
`S86.011A`	Strain of muscle, fascia and tendon of right lower leg, initial encounter	Soft-tissue injury may mimic or coexist with popliteal swelling and be considered in clinical evaluation.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`20610`	Arthrocentesis, aspiration and/or injection; major joint or bursa (e.g., knee)	Often performed prior to surgery for diagnostic aspiration or therapeutic decompression of a Baker cyst.
`29870`	Arthroscopy, knee, diagnostic, with or without synovial biopsy	Performed when intra-articular pathology is suspected and arthroscopic evaluation is planned in conjunction with cyst management.
`29871`	Arthroscopy, knee; synovectomy, limited	May be performed arthroscopically to address intra-articular synovial disease that contributes to cyst formation.
`27345`	Excision of popliteal cyst (Baker cyst)	Primary procedure to remove symptomatic synovial cyst from the popliteal space.
`99223`	Initial hospital care, typically 70 minutes or more	Example inpatient initial evaluation code used when patient requires hospital admission for perioperative management.
`99024`	Postoperative follow-up visit, global period (not billable separately when included)	Postoperative visits related to `27345` during the global period are typically included; use when separately billable per payer rules.