Hamstring Injuries
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Direct answer
Tear of the hamstring muscle-tendon unit is the commonest muscle injury in sport, and the mechanism tells you the site: maximal sprinting injures the long head of biceps femoris at the musculotendinous junction in late swing phase, when the muscle eccentrically decelerates the extending knee while the hip flexes, whereas a slip or fall with the hip forced into flexion avulses the conjoint tendon and semimembranosus from the ischial tuberosity. Biarticular architecture, off-season and pre-season periods, previous hamstring injury, higher age and low eccentric strength are the established risk factors. Ultrasound or magnetic resonance imaging grades the strain and predicts return time — the length of the lesion correlating with days lost — while plain films exclude an avulsed ischial apophysis in the young. Management is criterion-based rehabilitation through running progression, with surgical repair reserved for proximal avulsions with significant displacement or two-tendon tears.
What you must remember
- Anatomy: biceps femoris (long and short heads), semitendinosus and semimembranosus; all but the short head of biceps femoris cross two joints and arise from the ischial tuberosity — the long head of biceps femoris is the most frequently strained.
- Mechanism for the exam: eccentric deceleration during the late swing phase of sprinting, not the push-off; stretching injuries (water-skiing, slips) avulse the proximal tendon instead.
- Grading: grade I a tear of a few muscle fibres, grade II a partial tear with some strength loss, grade III complete rupture; MRI measures lesion length and cross-sectional involvement, both predicting lay-off.
- Askling L-test: active knee extension in the prone position — the extend-to-discomfort angle comparing sides guides readiness; the H-test angular deficit flags reinjury risk.
- Apophyseal variant: adolescents get ischial apophyseal avulsion rather than tendon rupture — conservative management usually, with delayed excision of a painful displaced fragment.
- Surgical indications for proximal avulsion: displacement commonly quoted as 2 cm or more, avulsion of two or more tendons, or an avulsion with a sciatic-nerve deficit; repair through transosseous tunnels or suture anchors close to the ischium.
- Prevention with numbers: the Nordic hamstring exercise programme, run one to three times weekly, reduces hamstring injury rates by roughly half in pooled analyses, with an even stronger effect on recurrent injuries.
From injury to return to play
Follow a 24-year-old sprinter who grabs the back of his thigh mid-stride. Day one: protect, avoid aggressive stretching and anti-inflammatics that may (per current debate) modestly slow early repair, begin pain-free isometrics. Days two to seven: restore range with gentle active movements, start walking progression; an MRI now — after about 48 hours, when the lesion is best delineated — grades the tear. Weeks two to four: progressive strengthening from isometric to heavy slow resistance, then running drills in straight lines at ascending speeds. The final phase is riskiest: askling-type criteria require pain-free completion of eccentric loading, a passing L-test angle within about 10 degrees of the other side, and sprint mechanics at full speed including abrupt deceleration. Return-to-play decisions are criteria-based, not calendar-based — reinjury rates historically approach a fifth of cases when athletes return by dates alone. Contrast the different patient: a 45-year-old who slipped on a wet floor, has a palpable defect below the ischial tuberosity and bruising down the thigh, cannot sit comfortably — that is a proximal avulsion; get an MRI, and if two tendons are retracted more than about 2 cm, repair within a few weeks before the sciatic nerve becomes ensnared in scar.
How the exam frames it
Two stems dominate. First, the mechanism question: the injury occurs in late swing, during active lengthening — candidates who answer "push-off" reveal memorisation without mechanics. Second, the avulsion question: displacement threshold and tendon number decide surgery, and the sciatic nerve is the structure at risk both from the original injury and from the surgical approach — quote it unprompted in the viva. Expect a prevention-style question too: which single intervention cuts recurrence most — the Nordic hamstring programme, an answer with a solid evidence base that examiners increasingly test. Indian practice angle: field-side management with massage and immediate stretching persists in local sport; the correct answer is protection and controlled loading, and the counselling point that most recurrences happen in the first month after return, so criteria matter more than certificates.
Frequently asked questions
Which hamstring muscle is most often injured in sprinters?
The long head of biceps femoris, typically at the musculotendinous junction, injured during the eccentric late swing phase of the gait cycle.
When is surgical repair indicated in proximal hamstring avulsion?
For complete avulsions with displacement of about 2 cm or more, involvement of two or more tendons, or an associated sciatic nerve deficit, ideally repaired early before retraction and scarring.
What is the Askling L-test?
Active knee extension performed prone, comparing the extendable pain-free angle between sides; a persistent deficit flags ongoing risk before return to sport.
Which exercise programme reduces hamstring injury rates most?
The Nordic hamstring eccentric programme, which pooled analyses suggest cuts injury risk by roughly half, with the largest benefit against recurrent injuries.
Why do adolescents get ischial apophyseal avulsion instead of tendon rupture?
The growth plate at the ischial tuberosity is weaker than the hamstring tendon, so a forceful hip-flexion injury separates the apophysis before the mature tendon gives way.