British Athletics Muscle Injury Classification (BAMIC)

Overview of the British Athletics Muscle Injury Classification (BAMIC) System

The British Athletics Muscle Injury Classification (BAMIC) system is a diagnostic tool developed to classify muscle injuries in athletes using MRI findings.
Its primary aim is to establish a standardized framework to guide treatment, rehabilitation, and communication among clinicians, coaches, and athletes.
This summary outlines the structure of the BAMIC system and reviews current literature regarding its utility in predicting return-to-play (RTP) outcomes.

Key Components of the BAMIC System

1.  MRI Protocol:

• Timing: MRI scans are ideally performed within 24–48 hours post-injury.

• Imaging Specifications: Scans are acquired using a 1.5 or 3 Tesla system in coronal, sagittal, and axial planes.

• Localization: Markers are placed at the site of maximum tenderness. If symptoms are diffuse, the entire thigh is imaged.

2.  Grading System:

Injuries are classified from Grade 0 to Grade 4. Grades 1–4 are further subdivided into classes a, b, or c:

• a – Myofascial

• b – Musculotendinous

• c – Intratendinous

The final injury grade is based on the highest letter and number combination.

Grade 1b: The injury is within the muscle or myotendinous junction (MTJ).

Grade 2: These are moderate tears that cause the athlete to stop activity due to pain.

• Grade 3: These are extensive tears that may cause the athlete to fall to the ground due to the sudden onset of pain.
  
• Grade 4: These are complete tears that may involve the myofascial, muscular, or myotendinous tissues. A Grade 4c injury indicates a tendon tear.
  

3. Grading Criteria

• Cross-Sectional Area (CSA):
  • Grade 1: <10%
  • Grade 2: 10–50%
  • Grade 3: >50%
• Length of Injury:
  • Grade 1: <5 cm
  • Grade 2: 5–15 cm
  • Grade 3: >15 cm
• Fiber Disruption:
  • Grade 1: <1 cm
  • Grade 2: <5 cm
  • Grade 3: >5 cm

Clinical Application and Limitations

The BAMIC system is valuable for:

• Enhancing communication among multidisciplinary teams.
• Offering a structured, reproducible approach for injury documentation.
• Providing some prognostic guidance regarding RTP.

However, limitations include:

• Population Bias: Originally validated in male elite athletes with hamstring injuries, limiting generalizability.
• Sport-Specific Variability: Muscle injury mechanisms differ across sports, affecting BAMIC’s external validity.
• MRI Limitations: MRI findings do not always correlate with functional recovery. Therefore, clinical judgment must remain central in RTP decisions.

BAMIC and Return-to-Play Outcomes

Research on BAMIC’s predictive value for RTP duration presents mixed findings:

• Pollock et al. (2021, 2015): Found intratendinous (“c”) injuries significantly delayed RTP and increased reinjury risk among elite track and field athletes.
• Kerin et al. (2024): In rugby union athletes, intramuscular tendon injuries had an average RTP of 78 days versus 24 days for non-tendinous injuries.
• Shamji et al. (2021): In professional soccer players, tendon involvement resulted in longer RTP (36 days vs. 24 days).
• Hollabaugh et al. (2023): Systematic review suggested MRI has limited utility in RTP decisions; emphasized that imaging does not reliably reflect tendon function.
• Hollabaugh et al. (2025): Retrospective study found no significant correlation between BAMIC grade and RTP in American football players with hamstring or quadriceps injuries.

Table 1 – Approximate Return to play based on MRI-BAMIC of muscle injury

Dr. Alex Francella and Dr. Neil Dilworth (April 22, 2025 – PR  )

References:

Aujla, R., Cecchi, S., Koh, E., D’Alessandro, P., & Annear, P. (2023). Surgical treatment of high‐grade acute intramuscular hamstring tendon injuries in athletes leads to predictable return to sports and no re‐injuries. Knee Surgery Sports Traumatology Arthroscopy, 31(10), 4601-4606. https://doi.org/10.1007/s00167-023-07477-x

Cooney, T., Reeve, A., Saw, A., Kountouris, A., Orchard, J., & Linklater, J. (2024). Hamstring strain grade on mri and return to play in elite australian cricket players.. https://doi.org/10.1101/2024.11.07.24316885

Eggleston, L., McMeniman, M., & Engstrom, C. (2020). High‐grade intramuscular tendon disruption in acute hamstring injury and return to play in australian football players. Scandinavian Journal of Medicine and Science in Sports, 30(6), 1073-1082. https://doi.org/10.1111/sms.13642

Hollabaugh, W., Sin, A., Walden, R., Weaver, J., Porras, L., LeClere, L., … & Sullivan, J. (2023). Outcomes of activity-related lower extremity muscle tears after application of the british athletics muscle injury classification: a systematic review. Sports Health a Multidisciplinary Approach, 16(5), 783-796. https://doi.org/10.1177/19417381231195529

Kerin, F., O’Flanagan, S., Coyle, J., Curley, D., Farrell, G., Persson, U., … & Delahunt, E. (2024). Are all hamstring injuries equal? a retrospective analysis of time to return to full training following bamic type ‘c’ and t‐junction injuries in professional men’s rugby union. Scandinavian Journal of Medicine and Science in Sports, 34(2). https://doi.org/10.1111/sms.14586

Kilcoyne, K., Dickens, J., Keblish, D., Rue, J., & Chronister, R. (2011). Outcome of grade i and ii hamstring injuries in intercollegiate athletes. Sports Health a Multidisciplinary Approach, 3(6), 528-533. https://doi.org/10.1177/1941738111422044

Kokubu, T., Mifune, Y., Kanzaki, N., Hoshino, Y., Kakutani, K., Inui, A., … & Kuroda, R. (2020). Muscle strains in the lower extremity of japanese professional baseball players. Orthopaedic Journal of Sports Medicine, 8(10). https://doi.org/10.1177/2325967120956569

Macdonald, B., McAleer, S., Kelly, S., Chakraverty, R., Johnston, M., & Pollock, N. (2019). Hamstring rehabilitation in elite track and field athletes: applying the british athletics muscle injury classification in clinical practice. British Journal of Sports Medicine, 53(23), 1464-1473. https://doi.org/10.1136/bjsports-2017-098971

Pollock, N., Kelly, S., Lee, J., Stone, B., Giakoumis, M., Polglass, G., … & Macdonald, B. (2021). A 4-year study of hamstring injury outcomes in elite track and field using the british athletics rehabilitation approach. British Journal of Sports Medicine, 56(5), 257-263. https://doi.org/10.1136/bjsports-2020-103791

Pollock, N., Patel, A., Chakraverty, J., Suokas, A., James, S., & Chakraverty, R. (2015). Time to return to full training is delayed and recurrence rate is higher in intratendinous (‘c’) acute hamstring injury in elite track and field athletes: clinical application of the british athletics muscle injury classification. British Journal of Sports Medicine, 50(5), 305-310. https://doi.org/10.1136/bjsports-2015-094657 Shamji, R., James, S., Botchu, R., Khurniawan, K., Bhogal, G., & Rushton, A. (2021). Association of the british athletic muscle injury classification and anatomic location with return to full training and reinjury following hamstring injury in elite football. BMJ Open Sport & Exercise Medicine, 7(2), e001010. https://doi.org/10.1136/bmjsem-2020-001010

Pollock N, James SL, Lee JC, Chakraverty R. British athletics muscle injury classification: a new grading system. Br J Sports Med. 2014 Sep;48(18):1347-51. doi: 10.1136/bjsports-2013-093302. Epub 2014 Jul 16. PMID: 25031367.

Hollabaugh W, Hill T, Davidson C, Pennings J, Strasser N, Porras L, Cox C, Fitch R. Application of the British Athletics Muscle Injury Classification in Collegiate Football Athletes: A Retrospective, Observational Study. Sports Health. 2025 Mar 27:19417381251326531.