R331 – Tibial lengthening
OHIP Radiology Code — MUSCULOSKELETAL SYSTEM SURGICAL PROCEDURES · Schedule of Benefits
R331 represents a surgical procedure from the N. Musculoskeletal System Surgical Procedures section of the Schedule of Benefits. As a surgical procedure, fees can be claimed by the operating surgeon (suffix A), a surgical assistant (suffix B), and an anaesthesiologist (suffix C). **Surgical Assistant (R331B):** The fee is calculated based on a combination of basic units and time units, multiplied by the assistant unit fee. Time is measured from when the assistant is in direct contact with the patient in the operating room until they are no longer required. Time units increase after the first hour and again after 2.5 hours. See the Surgical Assistants' Services section starting on page for detailed calculation rules. **Anaesthesiologist (R331C):** The fee is calculated by adding basic units and time units, multiplied by the anaesthesiologist unit fee. Time commences when the anaesthesiologist begins to initiate anaesthesia in the OR and ends when the patient is safely transferred to post-operative supervision. Time units increase after the first hour and again after 1.5 hours. Additional 'extra units' may be applicable based on patient factors like age, BMI, ASA physical status, and specific anaesthetic techniques used. See the Anaesthesiologists' Services section starting on page for detailed rules.
When to Use
- Use R331 for formal tibial lengthening procedures, distinguishing it from general fracture management codes like R990 or R993.
- Select R331 when the primary intent of the musculoskeletal intervention is the surgical lengthening of the tibia, rather than simple fixation or osteotomy.
Common Pitfalls
- Failure to document the Injury Severity Score (ISS) when attempting to claim the Trauma Premium (E420) will result in automatic rejection.
- Billing a second surgical assistant without prior authorization from a medical consultant is a common cause of claim denial; ensure the required letter of justification is prepared in advance.
- Confusing the time unit calculation rules between the surgical assistant (GP85) and the anaesthesiologist (GP92) leads to frequent billing errors.
Billing Tips
- Always verify if the procedure qualifies for age-based premiums (e.g., AGE_PREMIUM_5_TO_16_YEARS) as these are often applicable to pediatric tibial lengthening cases.
- For anaesthesiologists, ensure all relevant extra units (e.g., E022C for ASA III or E010C for BMI > 40) are appended to the claim to maximize the unit-based fee structure.
Effective: April 1, 2025
N. Musculoskeletal System Surgical Procedures
MUSCULOSKELETAL SYSTEM SURGICAL PROCEDURES
Surgical
Urogenital and Urinary Surgical Procedures
A service is only eligible for payment to the Supervising Physician when the medical record of the patient(s) identifies the Supervising Physician, the Medical Trainee and level of training, the description of the insured service performed by the Medical Trainee, patient consent to Supervision, and evidence of review by the Supervising Physician. See for full details.
When a second assistant is required, payment is only eligible following authorization by a medical consultant and requires submission of a letter from the surgeon outlining the reason.
For the Trauma Premium (E420) to be payable, the medical record must list the Injury Severity Score (ISS).
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