Hamstring Injuries in athletes
Introduction
Epidemiology
Most researchers agree that hamstring injuries comprise a substantial percentage of acute, sports-related musculoskeletal injuries [55]. In a study investigating the epidemiology of hamstring injuries among student athletes in 25 types of NCAA championship sports over 5 seasons, the incidence during competition per 10,000 athlete exposures was highest for men’s indoor track (15.70), soccer (14.69) and football(10.67) [38]. Significant loss of training time is observed (>28 days) in Australian Football and Soccer respectively [40]. Furthermore a high recurrence rates have been observed in sports, most notably in American football (32%), rugby union (21%) and soccer (16%)[40].
Risk Factors
HSI risk can categorized as modifiable and non-modifiable. Modifiable risk factors include: (1) Inadequate warm-up, (2) Increased training volume, (3)Muscle fatigue, (4) Hamstring inflexibility, (5) Hamstring weakness (may be weakness relative to ipsilateral quadriceps or contralateral hamstring), (6) Cross-pelvic posture (ie, lumbar lordosis with anterior pelvic tilt), (7) Lumbar-pelvic weakness, and (8) Poor biomechanics (eg, running or change of direction). Non modifiable risk factors are age, previous hamstring injuries, African or aboriginal ethnicity [56].
Hamstring Functional Anatomy
The hamstrings muscle group constitutes the posterior thigh, containing the semitendinosus, semimembranosus and biceps femoris (long and short head) (Figure 1). The hamstrings are biarticular group of muscles, specifically they cross and act at the hip and knee joint. This biarticular nature makes them susceptible to injury. The majority of hamstring strains occur in the biceps femoris (reported as high as 76-87% ) [25]. Semimembranosus and semitendinosus injuries are less common [25].
Pathophysiology
Hamstring injuries occur along a continuum ranging from mild strain at the myotendinous junction to the less common ischial tuberosity (proximal hamstring) injuries. A strain is a partial disruption of the musculotendinous unit. In contrast an avulsion is a discontinuity or complete disruption of the unit from its origin, for e.g proximal hamstring avulsion [23]. The majority of hamstring injuries occur at the musculotendinous junction of the biceps femoris [46]. In one study, 12.3% of 170 cases of hamstring injuries were tendon tears, and 87.7% were muscle belly injuries [24]. Although the vast majority of cases are non-surgical, the astute clinician must rapidly evaluate the type of hamstring injury to distinguish non-operative cases from operative cases. Furthermore, with posterior thigh pain, one must exclude hip and lumbar pathology via history and comprehensive musculoskeletal exam.
Proximal Hamstring Tendinopathy
Proximal hamstring tendinopathy, or high hamstring tendinopathy, is often insidious with a gradual onset of pain [57]. Pain in the proximal hamstring region is experienced during activity, when sitting on firm surfaces, or with prolonged sitting [57]. Evidence suggests that it more commonly affects middle-aged athletes and endurance athletes (long distance runners, cross country skiers, and cyclists) [57]. Most athletes with proximal hamstring tendinopathy have tenderness to palpation on the ischial tuberosity, local discomfort with minimal to no weakness of the hamstrings and gluteals, and local discomfort with flexibility testing with minimal to no limitation of hamstring length [57].
Classification
Initially described by O’Donoghue, hamstring injuries are categorized by the severity of muscle injury ranging from Grade I, Grade II or Grade III. Grade I (mild): Strain is mild and usually heals readily. Grade II (moderate): Partial tears associated with pain and loss of strength. Grade III (severe): Complete tears of the musculotendinous unit, resulting in complete loss of muscle function, and can be accompanied by a large hematoma [7].
The History and Physical Examination
Physical Examination
Inspection: Hip and knee symmetry should be assessed. The athlete’s gait should be observed and a “straight-legged” gait pattern may be visualized, as the patient attempts to avoid hip flexion and knee extension. Depending on the severity of the injury, bruising may also be noted (Figure 3) [11].
Diagnostic Studies
Treatment
Acute Grade I, II and Grade III Hamstring Strain Management.
Nonoperative treatment of is most commonly recommended in the setting of low-grade partial tears and insertional tendinosis [24].
Rehabilitation of Grade I, II and Grade III HSI.
Rehabilitation programs require a basic structure, with each case being personalized to maximize patient outcome.
Recurrent/ Chronic Hamstring Injuries.
Recurrence rates following hamstring injuries are high with the greatest incidence for re‐injury occurring within the first two weeks after return to sport [58]. The rate of reinjury is at least 30 percent, and some studies report rates as high as 60 to 70 percent [62]. Lifetime reinjury rates vary considerably by activity [56].
Orthopedic Surgical Evaluation.
Surgical referral is recommended for complete (Grade III) proximal hamstring rupture high grade (Grade II or III) distal hamstring tears [56]. Nonoperative treatment of complete ruptures of the proximal hamstring is less frequently recommended because surgical repair has resulted in the successful return of patients to a high level of function.
Other Treatment Modalities
Conclusion
– More on acute hamstring injuries: https://wikism.org/Hamstring_Strain
– More on chronic hamstring tendinopathies: https://wikism.org/Proximal_Hamstring_Tendinopathy
Authors
- Assistant Professor Department of Orthopaedics and Department of Family Medicine, Community Health
- Team Physician – U of Miami Department of Intercollegiate Athletics
- Team Physician – Miami Marlins
- University of Miami MIller School of Medicine
- PGY2 Resident Physician
- Department of Family Medicine and Community Health
- University of Miami Miller School of Medicine.
- Professor of Orthopedics, Family Medicine, Biomedical Engineering, Kinesiology
- Research Director – UHealth Sports Medicine Institute
- Director – Primary Care Sports Medicine Fellowship
- Team Physician – U of Miami Department of Intercollegiate Athletics
- Team Physician – Miami Marlins
- U of Miami Miller School of Medicine
References
42. The Anatomy Lesson by Wesley Norman (Georgetown University): website http://www.wesnorman.com/postthigh.htm]