{"id":10012,"date":"2022-02-11T07:00:03","date_gmt":"2022-02-11T06:00:03","guid":{"rendered":"https:\/\/blogs.bmj.com\/bjsm\/?p=10012"},"modified":"2022-02-06T16:56:45","modified_gmt":"2022-02-06T15:56:45","slug":"reducing-hamstring-injury-burden-and-re-injury-rates-the-development-and-application-of-bamic","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/bjsm\/2022\/02\/11\/reducing-hamstring-injury-burden-and-re-injury-rates-the-development-and-application-of-bamic\/","title":{"rendered":"Reducing hamstring injury burden and re-injury rates: the development and application of BAMIC"},"content":{"rendered":"

Why<\/em> develop a new muscle injury classification?<\/em><\/strong><\/p>\n

The British Athletics Muscle Injury Classification (BAMIC) was developed in 2014 as part of a hamstring strategy.[1] An internal report in our elite track and field squad established that hamstring injury was the leading cause of missed time from training and competition. The muscle injury grading systems available at that time, had a lack of consistency in terminology and lack of clarity regarding diagnostic entities. In particular, the modified Peetron\u2019s grading system and the Munich consensus did not acknowledge injury to the intramuscular tendon.[2,3] We considered that due to different healing processes within muscular and tendon tissue that outcomes and ideal management may be different depending on the injured structure. The British Athletics Muscle Injury Classi\ufb01cation (BAMIC) was developed and is an MRI based diagnostic system, detailing the severity (grades 0\u20134) and site of injury (myofascial(a), muscle-tendon junction (b) or intratendinous (c). (Figure 1)[1]<\/p>\n

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Figure 1<\/strong>. BAMIC Letter classification dependent on anatomical site of muscle injury. (a)Myofascial (b) Musculo-tendinous (c) Intratendinous[1]<\/figcaption><\/figure>\n
<\/h6>\n

What<\/u><\/em><\/strong> we have learnt from the application of the BAMIC system <\/u><\/em><\/p>\n

The BAMIC system has been applied in both our own and other elite sport settings.<\/p>\n

British Athletics outcomes<\/u><\/em><\/p>\n

A retrospective study in our track and field group demonstrated time to return to full training (TRFT) was delayed and recurrence rate higher in intratendinous (\u2018c\u2019) acute hamstring injuries.(Figures 2, 3 and 4)[4] Therefore the recognition and categorisation of intratendon injuries was considered to be important and strategies developed with the intention of improving the rehabilitation and outcomes of these injuries.<\/p>\n

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Figure 2<\/strong> Mean time \u00b1SD time to return to full training (BA British Athletics; TRFT, time to return to full training)[4]<\/figcaption><\/figure>\n

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Figure 3<\/strong> Reinjury rates in BAMIC groups in first injury outcome paper[4]<\/figcaption><\/figure>
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Figure 4<\/strong> Example of a 3c intramuscular tendon injury[14]<\/figcaption><\/figure>Studies on BAMIC in other sporting groups<\/u><\/em><\/p>\n

Subsequent studies in elite professional Australian Rules Football[5], football[6\u20138] and elite rugby[9] have demonstrated significantly longer time to return to play in \u2018c\u2019 hamstring injuries. The loss of tension and waviness within the tendon in this type of injury appears most relevant to outcome. However, in a recent study in elite English football, 2c hamstring injuries (i.e. those without loss of tension) were not associated with increased time to RTP or reinjury.[10] These studies also demonstrate the success of non-surgical rehabilitation in intratendon injuries, including high grade 3c intratendon injuries.<\/p>\n

How<\/u><\/em><\/strong> we developed a new way of doing things <\/u><\/em><\/p>\n

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Figure 5<\/strong> Infographic from the British Athletics rehabilitation paper (with thanks to Dr Robin Chakraverty and illustrator Louise Carrier)[11]<\/figcaption><\/figure>\n

A specific and targeted rehabilitation strategy for hamstring injuries, particularly intratendon injuries, based on our classification system was developed.[11] We applied knowledge of both muscle and tendon healing physiology to identify appropriate rehabilitation strategies.(Figure 5) Please note that the suggested healing times in Figure 4 relate to tissue healing and not direct clinical or functional recovery. It is well established that full tissue healing and normal imaging is not required for clinical recovery.[12,13] The principles we applied in rehabilitation included shared decision making with coaches and athletes, nutritional strategies to support healing and an individualised risk factor review. Targeted strengthening programmes were applied for specific injuries. In high grade intratendon injuries, we considered that initial limitation of eccentric contractions and running speed, which produce higher strains on the tendon, was important, before then applying appropriate loads to support tendon healing and adaptation. In all rehabilitations, progressive return to functional movements and high speed running was essential.<\/p>\n

Our implementation of the classification system and the principles of rehabilitation helped to: improve the recognition of injuries associated with higher recurrence rates, provide a common language to enhance communication between all stakeholders, facilitate a shared decision making process based on risk between the coach, athlete and support staff and target rehabilitation to the injured tissue and for a specific goal.<\/p>\n

What <\/strong>was the outcome?<\/strong><\/p>\n

We recently published our recent hamstring injury outcomes following implementation of our management strategy.[14] We noted a re-injury rate of 2.9% which compares favourably with other published epidemiological studies and our previous work.(Figure 6) Importantly the average TRFT for most injury classes, with the exception of 2c injuries which increased by 1 week, were not higher, demonstrating that our reduced re-injury rates were not caused by simply taking a more cautious approach.(Figures 2 and 7) Our recent work also demonstrated that tendon cross-sectional area involvement and loss of tension was associated with longer TRFT, and longitudinal splits were less important which may be important in future development of the BAMIC system. Our work in hamstring injuries over the last decade has confirmed to us that excellent functional outcomes, including return to medal winning track and field performances at global championships, is reliably possible with rehabilitation and without surgery, even in high grade injuries that involve intramuscular tendons.<\/p>\n

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Figure 6<\/strong> Comparison of reinjury rates (%) between 2010-2014 and 2015-2019 in the different BAMIC categories<\/figcaption><\/figure>\n

 <\/p>\n

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Figure 7<\/strong> Median \u00b1 IQR (days) time to return to full training in different BAMIC categories in new 2021 paper[14]<\/figcaption><\/figure>\n

Conclusion<\/strong><\/p>\n

The outcomes in our most recent paper come from working through the van Mechelen \u2018sequence of prevention model\u2019 (Fig.8). In this the problem was identified, a potential solution was developed and implemented and its effectiveness was evaluated.[15,16] The use of the BAMIC in elite sporting populations, where the demand on the muscle-tendon unit is significantly greater compared to non-elite populations, indicate that injuries involving intratendon injuries may require longer to successfully return to play than muscular injuries. The rehabilitation of different injuries may be optimised with targeted strategies including exercise prescription and appropriate time for recovery. Further research is required to investigate the clinical correlates of intramuscular tendon injury as these may be difficult to detect clinically[17] and the role of surgery in high grade 3c and 4c injuries is still to be determined. The BAMIC system can help to inform effective decision making on RTP\/RTFT and rehabilitation progression.<\/p>\n

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Figure 8.<\/strong> adapted van Mechelen sequence of prevention model[15,16]<\/figcaption><\/figure>\n

Take Home Messages:<\/strong><\/p>\n