SLR - March 2021 - P. Tanner Shaffer

Return to Play and Recurrence After Calf Muscle Strain Injuries in Elite Australian Football Players

Reference: Green B, Lin M, McClelland JA, Semciw AI, Schache AG, Rotstein AH, Cook J, Pizzari T. Return to Play and Recurrence After Calf Muscle Strain Injuries in Elite Australian Football Players. Am J Sports Med. 2020 Nov;48(13):3306-3315. doi: 10.1177/0363546520959327. Epub 2020 Oct 8. PMID: 33030961.

Level of Evidence: Level 3 Case Control Study

Scientific Literature Review

Reviewed By: P. Tanner Shaffer, DPM
Residency Program: Mercy Hospital and Medical Center – Chicago IL

Podiatric Relevance: Calf muscle strain injuries (CMSI) are costly injuries that can have significant variability in severity and presentation. This is illustrated by a wide range of return to play (RTP) periods; from no time loss at all from competition to time losses of greater than 120 days. Though CMSI can have a huge impact on athletic competition, there is little information on factors that may affect outcomes. Clinical and MRI findings could help delineate factors that affect RTP. While it is known that running related CMSI’s have yielded a greater time to RTP compared to non-running CMSI’s, and that injuries to the central intramuscular aponeurosis have the longest average time to RTP (44 +- 23 days), it is unclear about CMSI at other locations. This study aimed to describe MRI findings of CMSI and see if MRI findings with clinical data correlated to time to RTP and injury recurrence. 

Methods: Clinical and MRI data were collected from the Australian Football League (AFL). Clinical data included demographics, history at the time of index injury, and CMSI mechanism. Running related CMSI mechanisms included high intensity running, acceleration, steady state running, and deceleration. Non-running related mechanisms included jumping, landing, kicking, gradual onset and all other mechanisms. Time to achieve pain free walking, return to full training, and to RTP were also recorded. MRIs were examined to identify which muscles underwent injury, where on the muscle the injury occurred, and the presence and severity of aponeurotic disruption (AD). Clinical and radiologic data were examined to identify trends. 

Results: The 149 cases were comprised of 114 index injuries and 35 recurrent. The soleus or gastrocnemius were the primary muscles involved in 95.9 percent of injuries. The soleus was the primary muscle involved in 126 (84.5 percent) of 149 cases and the gastrocnemius in 17 (11.4 percent). Regardless of anatomical location or muscle involved on MRI, players with CMSI with severe AD on MRI took longer to RTP than players with CMSI with no AD (avg 31.3 days vs 19.4 days, P = .003). The presence of any degree of AD was associated with longer RTP times for specifically soleus injuries (p =0.025). Running related MOI’s were also associated with a longer RTP (p = 0.019). Clinical findings—mainly older age and a history of CMSI increased the risk of CMSI recurrence within two seasons (p = 0.013). No specific MRI findings were correlated to increased risk of recurrence. 

Conclusions: This study demonstrates that clinical factors (age and a previous CMSI history) may be more useful in predicting CMSI recurrence than MRI findings. However, with regards to RTP, this study shows that AD on MRI (for soleus injuries) and a running related MOI may be useful in predicting a longer RTP. The authors noted that aponeurotic involvement on MRI may prolong RTP because aponeurotic tissue notoriously takes longer to heal. This study is important because it allows the podiatric physician to better educate their patients (especially higher-level athletes) who suffer CMSI’s based on clinical as well as radiologic findings.

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