Proposed modified classification system of the Munich Consensus Statement : can the area of haemorrhagic effusion in muscle injuries be the dividing line between mild (3A) and moderate (3B) injuries?

Purpose: Muscle injuries are common in competitive sports. Magnetic resonance imaging (MRI) and ultrasound (US) are the most commonly used methods for evaluating muscle injuries. Several classification systems for muscle injuries have been published. Mueller-Wohlfahrt et al. introduced a new classification system in 2013, currently the most widely used, employing grading to reflect the diverse spectrum of muscle injuries observed in athletes. The differentiation between lesions classified as type 3A (minor partial muscle tear) and 3B (moderate partial muscle tear) remains to be precisely established. In relation to recovery time, we researched possible statistically significant differences. Material and methods: We conducted a comprehensive analysis of 100 MRI studies that were performed on high-level professional athletes who exhibited clinical signs of lower limb muscle injuries. We selected individuals whose myotendinous or myofascial lesions could be classified as 3A or 3B, based on the Mueller-Wohlfarth (MW) classification. The athletes were then categorised into groups based on the presence or absence of fluid collection at the site of injury. The study’s medical practitioner provided data regarding the duration of the injury and the return to sporting activities. Regarding statistical analyses, a linear regression test was conducted to examine the correlation between the variable "fluid collections" and the duration of the injury. Following this, Fisher’s t-test or the Mann-Whitney test was applied. Results: The results of the association between "blood collection" and "duration of injury" revealed a statistically significant correlation. The median value of return to play (RTP) in patients with haemorrhagic collection (median = 29) was significantly higher in comparison with patients without haemorrhagic collection (median = 19), with a difference between the 2 samples of 10 days. Conclusions: Our study highlights how this distinction could be easily practiced by recognizing the presence of a haemorrhagic collection and how it predominates in determining a worsening of the prognosis and therefore an extension of the RTP. Hence, we can conclude that athletes who do not have blood collection , but only interstitial haemorrhage between fibres can be considered as type 3A, while athletes with interstitial haemorrhage at diagnosis can be considered as type 3B.