Hamstring strains in athletes: diagnosis and treatment.

Clanton TO, Coupe KJ. J Am Acad Orthop Surg 1998 Jul-Aug;6(4):237-48.

Hamstring strains are among the most common injuries (and reinjuries) in athletes. Studies combining electromyography with gait analysis have elucidated the timing of activity of the three muscles of the hamstring group; they function during the early-stance phase for knee support, during the late-stance phase for propulsion, and during midswing to control the momentum of the leg. Muscle injury, whether partial or complete, occurs at the myotendinous junction, where force is concentrated. The healing response begins with inflammation, associated edema, and localized hemorrhage. After an initial period of reduced tension, the healing muscle regains strength rapidly as long as reinjury does not occur. Although the use of anti-inflammatory medication is a keystone of treatment, a certain degree of inflammation is necessary for removing necrotic muscle fibers and rescaffolding to allow optimal recovery. The protocol of rest, ice, compression, and elevation is still the preferred first-aid approach. After a brief period of immobilization (usually less than 1 week for even the most severe strain), mobilization is begun to properly align the regenerating muscle fibers and limit the extent of connective tissue fibrosis. Concurrent pain-free stretching and strengthening exercises (beginning with isometrics and progressing to isotonics and isokinetics) are essential to regain flexibility and prevent further injury and inflammation. Readiness for return to competition can be assessed by isokinetic testing to confirm that muscle-strength imbalances have been corrected, the hamstring-quadriceps ratio is 50% to 60%, and the strength of the injured leg has been restored to within 10% of that of the unaffected leg. The only indication for surgery is a complete rupture at or near the origin from the ischial tuberosity or distally at its insertion (either soft-tissue avulsion with a large defect or bone avulsion with displacement by 2 cm).

Hamstring injuries. Current trends in treatment and prevention.

Kujala UM, Orava S, Jarvinen M. Sports Med 1997 Jun;23(6):397-404.

Pre-exercise stretching and adequate warm-up are important in the prevention of hamstring injuries. A previous mild injury or fatigue may increase the risk of injury. Hamstring muscle tear is typically partial and takes place during eccentric exercise when the muscle develops tension while lengthening, but variation in injury mechanisms is possible. Diagnosis of typical hamstring muscle injury is usually based on typical injury mechanism and clinical findings of local pain and loss of function. Diagnosis of avulsion in the ischial tuberosity, with the need for longer immobilisation, and a complete rupture of the hamstring origin, in which immediate operative treatment is necessary, poses a challenge to the treating physician. X-rays, ultrasonography or magnetic resonance imaging (MRI) may be helpful in differential diagnostics. After first aid with rest, compression, cold and elevation, the treatment of hamstring muscle injury must be tailored to the grade of injury. Conservative treatment is based on a knowledge of the biological background of the healing process of the muscle. Experimental studies have shown that a short period of immobilisation is needed to accelerate formation of the granulation tissue matrix following injury. The length of the immobilisation is, however, dependent on the grade of injury and should be optimised so that the scar can bear the pulling forces operating on it without re-rupture. Mobilisation, on the other hand, is required in order to regain the original strength of the muscle and to achieve good final results in resorption of the connective tissue scar and re-capillarisation of the damaged area. Another important aim of mobilisation–especially in sports medical practice–is to avoid muscle atrophy and loss of strength and extensibility, which rapidly result from prolonged immobilisation. Complete ruptures with loss of function should be operated on, as should cases resistant to conservative therapy in which, in the late phase of repair, the scar and adhesions prevent the normal function of the hamstring muscle.

Ischial tuberosity apophysitis and avulsion among athletes.

Kujala UM, Orava S, Karpakka J, Leppavuori J, Mattila K. Int J Sports Med 1997 Feb;18(2):149-55

Ischial tuberosity pain in athletes may be caused by several clinical entities, which include acute and old bony or periosteal avulsions and apophysitis. We studied the natural course of these injuries based on our clinical case series of fourteen patients with apophysitis and twenty-one with avulsion of the ischial tuberosity. Only patients with the diagnosis confirmed by X-ray finding were included. The clinical diagnostic criteria by ischial apophysitis consisted of gradually increasing functional and palpatory pain at the ischial tuberosity without any major trauma at the beginning of the symptoms. Typically there was asymmetry on plain radiographs of the ischial tuberosities in apophysitis; the involved apophyseal area became sclerotic, wider than the non-symptomatic apophysis, osteoporotic patches developed and the lower margin of the ischial tuberosity became irregular. The patients with avulsion reported an acute trauma at the beginning of the symptoms and an avulsion fragment was immediately after injury or later seen in plain radiographs. The mean age of the patients with apophysitis (14.1 yrs) was lower than that of the subjects with avulsions (18.9 yrs). Apophysitis of the ischial tuberosity usually healed well without complications. Avulsions often caused more prolonged pain with referral pain to the posterior parts of the thigh which often required operative interventions. A small bony or periosteal avulsion sometimes grew to a pseudotumor calcification. We recommend conservative treatment as the primary treatment modality for both ischial tuberosity apophysitis and avulsion fractures.