Clinical Context
A typical patient is a 68-year-old woman with chronic knee osteoarthritis and deconditioning referred by her primary care provider to participate in supervised group exercise classes led by a licensed physical therapist assistant or certified exercise instructor. The goal is to improve joint mobility, muscle strength, balance, and aerobic capacity to reduce pain and fall risk. The patient presents to an outpatient rehabilitation clinic or community wellness center for a scheduled 60-minute session billed as S9451 (exercise classes, non-physician provider, per session). Clinical workflow includes: initial screening and brief functional assessment by the supervising clinician, group warm-up, targeted strengthening and range-of-motion activities, balance and gait training, and cooldown with home exercise recommendations. Vital signs are checked as indicated and participant response is documented in the medical record. Sessions are typically recurring on a weekly basis and may be part of a broader plan of care that includes periodic reassessment by a licensed clinician (e.g., physical therapist) and coordination with the referring provider.
Coding Specifications
| Modifier | Description | When to Use |
|---|
00 | No modifier | Use when no billing modifier applies to the session |
| 22 | Increased procedural services | Use when the exercise session required substantially greater effort, time, or intensity than typical for S9451 (document justification)
| 52 | Reduced services | Use when the session was partially reduced or not fully rendered compared with a typical full session
| 53 | Discontinued procedure | Use when the session was started but terminated due to patient condition or inability to continue
| 55 | Split (or shared) professional service | Use when more than one clinician shares responsibility for the session and billing requires split reporting
| 56 | Preoperative services | Generally not applicable but used if session is billed in the context of preoperative conditioning when payer permits
| 62 | Two surgeons | Rarely applicable; use only if two qualified providers of different specialties shared active management of the session and payer allows
| 95 | Synchronous telemedicine service rendered via real-time interactive audio and video | Use when the group exercise session is delivered live via telehealth by a non-physician provider
| AS | Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery | Not typically applicable; included for completeness when an advanced practice clinician documents primary delivery
| QX | Modifier indicating services performed by a certified nurse-midwife or similar when paired with QK/QY for modifier combinations | Use when payer-specific modifier requirements require identifying the supervising arrangement for non-physician providers
| Taxonomy Code | Specialty | Notes |
|---|
173C00000X | Physical Therapist | Primary supervising clinician for therapeutic exercise classes |
| 160Z00000X | Physical Therapist Assistant | Common direct provider delivering the exercise session under PT supervision
| 103G00000X | Exercise Physiologist | Delivers structured exercise classes for chronic disease management
| 374K00000X | Recreational Therapist | Provides group therapeutic exercise focusing on function and psychosocial benefit
| 363A00000X | Occupational Therapist | May provide activity-based group sessions when functional ADL goals are primary
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|
M17.11 | Unilateral primary osteoarthritis, right knee | Common indication for supervised exercise to improve strength and reduce pain |
| M17.12 | Unilateral primary osteoarthritis, left knee | As above for the contralateral knee
| M25.561 | Pain in right knee | Symptom commonly addressed with therapeutic exercise classes
| M25.562 | Pain in left knee | Symptom commonly addressed with therapeutic exercise classes
| M62.81 | Muscle weakness (generalized) | Deconditioning treated with progressive exercise programs
| R26.2 | Difficulty in walking, not elsewhere classified | Mobility limitation improved through structured exercise and gait training
| M19.90 | Unspecified osteoarthritis, unspecified site | Broad osteoarthritis diagnoses that may be managed with exercise interventions
| Z71.89 | Other specified counseling | Used when the session includes lifestyle or exercise counseling as part of the visit
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|
97110 | Therapeutic exercises to develop strength and endurance, range of motion and flexibility (each 15 minutes) | Often provided before, during, or in individualized sessions accompanying S9451 when targeted one-on-one therapeutic exercise is needed |
| 97112 | Neuromuscular reeducation of movement, balance, coordination, kinesthetic sense, posture, and proprioception (each 15 minutes) | Used for focused balance and gait training when individual treatment is billed in addition to group exercise
| 97116 | Gait training (includes stair climbing) (each 15 minutes) | Billed when individualized gait training occurs separate from the group class
| 97530 | Therapeutic activities, direct (one-on-one) patient contact by the provider, use of dynamic activities to improve functional performance (each 15 minutes) | Complementary individualized functional training that may precede or follow group sessions
| 97535 | Self-care/home management training (e.g., activities of daily living, compensatory training) | Used when the provider documents specific home exercise instruction or ADL training in addition to S9451