Intramuscular Tendon Injuries of the Hamstring Muscles: A More Severe Variant? A Narrative Review

Area of Science:

• Sports Medicine
• Orthopedic Surgery
• Rehabilitation Science

Background:

• Hamstring strain injuries (HSI) are prevalent in sports, characterized by high injury burden and recurrence.
• Intramuscular tendon (IMT) involvement in HSI, present in up to 41% of cases, is associated with prolonged return to play (TTRTP) and high re-injury rates, particularly in elite athletes.

Purpose of the Study:

• To determine if IMT injuries constitute a distinct clinical entity with unique outcomes compared to other hamstring injuries.
• To review current evidence on IMT injury, including anatomy, imaging, clinical assessment, rehabilitation, and surgical considerations.

Main Methods:

• A systematic literature search was conducted to identify studies on HSI involving the IMT in athletes.
• This narrative review synthesizes existing evidence on IMT injury characteristics and management.

Main Results:

• Clinical outcomes like TTRTP and re-injury rates vary significantly across different sports and athlete populations.
• Bespoke rehabilitation strategies targeting IMT injuries have demonstrated a significant reduction in re-injury rates among elite track and field athletes, without negatively impacting TTRTP.

Conclusions:

• IMT hamstring injuries may warrant classification as a distinct clinical entity due to their specific impact on TTRTP and re-injury risk.
• Further prospective research is needed across diverse sports to refine clinical findings, surgical indications, and outcomes for IMT injuries.