Proximal Hamstring Avulsion

Sciatica from lumbar disc: Pain radiates below the knee, positive straight-leg raise, no palpable gap.

Ischiogluteal bursitis: Chronic pain on sitting, no acute event, no weakness.

Hamstring muscle strain (mid-belly): Tender in the posterior thigh, not at the ischium; no gap.

Apophysitis / apophyseal avulsion in adolescents: Similar pain at the ischial tuberosity in skeletally immature athletes (14-25 years); pelvic X-ray shows widened apophysis.

Piriformis syndrome: Buttock pain with sciatic distribution but no ischial defect or post-traumatic onset.

Not every ischial-region complaint is an avulsion. Proximal (high) hamstring tendinopathy is a chronic insertional/overuse tendinopathy of the conjoint origin, classically in distance runners and sprinters, with deep buttock/ischial pain that is worst on sitting and during the acceleration or lengthening phase of running - an insidious onset with no pop, no palpable gap and preserved strength, unlike an acute avulsion. It overlaps with, and must be separated from, ischiogluteal bursitis and deep gluteal (sciatic entrapment) syndrome. MRI or ultrasound shows tendon thickening, intratendinous signal and peritendinous oedema without a retracted stump. Management is non-operative and load-based: relative rest and sitting modification, then a progressive eccentric / heavy-slow-resistance hamstring programme (the mainstay), with extracorporeal shockwave therapy and a carefully placed imaging-guided peritendinous injection (avoiding intratendinous corticosteroid and the sciatic nerve) as adjuncts; surgical debridement or tenotomy is reserved for the refractory minority. This is the answer to "how does it differ from hamstring syndrome and from an avulsion?".

Q: Which two tendons share the conjoint origin at the ischial tuberosity? A: Biceps femoris (long head) and semitendinosus. They share a common footprint on the posteromedial ischial tuberosity. The semimembranosus has a separate, more anterolateral origin. This anatomy explains why a 2-tendon avulsion is usually the conjoint and a 3-tendon avulsion is the complete origin.

Q: What is the classic mechanism of a proximal hamstring avulsion? A: Forced hip flexion with the knee in extension - eccentric overload of a contracting hamstring. Common in water skiing (fall with knee extended), sprint starts, hurdling, and dashboard injuries. A pop is typically felt in the buttock, followed by immediate pain and weakness.

Q: In the Wood classification, what retraction distance indicates a surgical repair? A: Greater than 2 cm of retraction (Type III or Type IV). Type I (osseous avulsion, minimal displacement) and Type II (less than 2 cm retraction) may be treated conservatively depending on patient demand. Type III (2-5 cm) and Type IV (greater than 5 cm) are operative indications.

Q: What is the ideal timing for surgical repair of an acute proximal hamstring avulsion? A: Within 4 weeks of injury (acute window). Acute repair produces better strength recovery, higher return-to-sport rates, and lower complication rates than delayed repair. Beyond 12 weeks, the stump retracts and may not reach the ischium, sometimes requiring allograft.

Q: What is the relationship of the sciatic nerve to the proximal hamstring origin, and why does it matter? A: The sciatic nerve lies posterior to the ischial tuberosity and the hamstring origin, passing distally into the thigh. It is at risk during surgical repair (must be identified first) and can become tethered by scar tissue in chronic avulsions (causing hamstring syndrome with sitting pain and sciatic dysaesthesia).

Q: What is the post-operative bracing protocol after proximal hamstring avulsion repair? A: Hip-knee brace locked at 30-60 degrees of knee flexion for 4-6 weeks, non-weight-bearing with crutches for 6 weeks, then progressive loading. The knee is flexed at brace application to offload the repair, since tying was performed with the knee flexed. Eccentric strengthening starts at 6-8 weeks; return to sport typically at 6-9 months.