Hamstring Strain Injuries3003PES – Injury Prevention and Management By DION OBST
Table of Contents• Introduction • Mechanism of Injury• Definitions • Clinical Diagnosis• Aetiology • Differential Diagnosis• Anatomy of the Hamstring • Phases of Injury and Treatment• Physiology of the Hamstring • Rehabilitation• Muscle Physiology • Rehabilitation and Injury Prevention•Young athletes and Hamstring Strains • Literature Review• Biomechanics of the Hamstring • References
Introduction • A variety of studies have found that hamstring injuries are the most common injury in AFL, athletics (sprinting), soccer, cricket and touch football (Hoskins, 2005). •Hamstring strain injuries typically occur in sports that involve rapid high speed activity, rapid acceleration and/or strenuous stretching manoeuvres. • Brockett et.al (2004) investigated AFL injuries and estimated approximately 16% of all injuries cases are hamstring strains. • The evidence suggests that the chance of re-injury to the hamstring occurs in 34% of cases (Brockett, 2004).Source: http://www.fotosearch.com/ Source: http://mm.afl.com.au/
Definitions A muscle strain can be defined as excessive stretching or tearing (complete or partial) of the muscle fibres and is graded according to the severity. Common names for a hamstring strain injury include: • Biceps Femoris strain • Torn ‘Hammy’ • Pulled hamstring A hamstring strain involves stretching and/or partial tearing of one or more of the 4 hamstring muscle groupsSource: http://www.return2fitness.co.uk
Aetiology Hamstring strain injuries are graded according to their severity: Grading SeverityGrade 1 (Mild) Small % of fibres are stretched or torn, mild pain, minimal to no loss of strength.Grade 2 (Mod) Significant % of torn fibres, swelling, pain with active ROM, loss of strength, palpable deformity.Grade 3 (Severe) Complete tearing of fibres and/or MT junction, gross impairment, severe initial pain. Source: http://www.sportsinjuryclinic.net Muscles that are most susceptible to strains are those in which their origin and insertion points span over two joints (Noonan,1999). Untrained athletes are more prone to hamstring-related injuries during exercise that involves eccentric muscle contraction.
AetiologyThe most common causal factors of Normal hamstring strain injuries are:• Poor flexibility and strength• Strength imbalance betweenquadriceps and hamstring musclegroups• Strength imbalance between glutealsand abdominal muscle groups• Inadequate warm-up techniques• Previous hamstring injuries• Over exertion or excessive stretching• Muscle fatigue• Differences in leg length (Increasedtension on shorter leg) Poor flexibility Great flexibility
Anatomy of the Hamstring The hamstring comprises of 3 major muscles: 1) Biceps Femoris (long and short head) 2) Semitendinosis 3) Semimembranosis The hamstrings span over two joints - the hip and the knee joint Muscle Origin Insertion 1. Ischial Tuberosity Head of Fibula (lateral side) (long) (short) Linea Aspera Head of Fibula (lateral side) 2. Ischial Tuberosity Tibia (medial surface) 3. Ischial Tuberosity Tibial Condyle (medial) (Hoskins & Pollard, 2005)Source: http://www.fotosearch.com/
Physiology of the Hamstring• Eccentric contractions of the hamstring are believed to resultin microscopic muscle damage to the muscle fibres (Brockett,2004).• A local inflammatory response is initiated following injury.• This mechanism is believed to have a role in sensitizing musclenocioreceptors and mechanoreceptors (Morgan, 1999).• Untrained individuals are more prone to muscle strain injurieswhich may result in reductions in muscle tension and theoptimal length to generate tension is increased (Morgan, 1999).
Muscle Physiology• Muscle fatigue is thought to play a major role in contributing tomuscle damage.• Muscles that commonly experience strain type injuries are composedof Type II (Fast-twitch) fibres (i.e. Hamstring).• An strength imbalance may also exist between the quadriceps and thehamstring. The quadriceps are typically stronger and therefore thehamstrings often fatigue much faster (Petersen & Holmich, 2005).•This results in the inability of the hamstring muscles to adequatelyrelax during contraction of the quadriceps, therefore strains occur(Petersen & Holmich, 2005).• Other causal mechanisms include changes in excitation-contractioncoupling, Ca2+ sensitivity and sarcomere recruitment (Morgan, 1999).
Young Athletes and Hamstring Strains• During growing periods, muscles andbones have the tendency to grow atdifferent rates.•Young athletes may be subjective tohamstring strain injuries if their bones Source: https://console.clubsonline.com.au/grow at a faster rate than their muscles.• This causes greater stretch on themuscle fibres and therefore a suddenmotion such as jumping may lead toexaggerated stretch or muscle tearingfrom the bone (Brockett, 2004). Source: http://images.conquestchronicles.com/
Biomechanics of the HamstringThe biomechanical role of the hamstrings include: • Knee Flexion (heel towards gluts) • Hip Extension (backwards movement of leg) • Deceleration of the knee ( quadriceps antagonist) Source: http://www.albionrundoctor.com/
Biomechanics of the Hamstring During gait, injuries most commonly occur at the end stage of the swing phase (Hoskins & Pollard, 2005). MUSCLE ACTIONSemitendinosis/ Predominantly involved in hip extension. Also knee flexionSemitendinosis and internal rotation of lower leg.Biceps Femoris (long) Hip extension at beginning of gait cycleBiceps Femoris Knee flexion and external rotation of the lower leg.(Long & Short Head) Mechanoreceptors in the ACL provide proprioceptive information to the hamstring muscles, causing them to activate at the end of the swing phase of gait (Hoskins & Pollard, 2005). This may explain the reason why those who previous experienced knee injuries are prone to hamstring strain injuries.
Biomechanics of the HamstringA study by Askling et.al (2006), examined the differences inthe recovery period of two types of acute hamstring strains.• A group of 18 elite sprinters an 15 dancers diagnosed withhamstring strains were examined• The sprinters experienced the injury during high speedrunning, whereas the dancers developed the strain via slowstretching exercisesRESULTS: Initially, the sprinters experienced the greatest lossof function, however the dancers required significantlygreater time to return to pre-injury level:-Median (Sprinters) – 16 weeks (range 6-50)Median (Dancers) – 50 weeks (range 30-76)
Mechanisms of InjuryThe evidence strongly suggests that athletes who have experiencedhamstring injuries previously, are most susceptible to recurringhamstring strains (Orchard, 1997).Eccentric contraction of the hamstrings is known to cause microscopicdamage to the muscle fibres. Tearing of fibres begins when the forceapplied exceed 80% of the force required to agitate the muscle(Malliaropoulos et.al,2004).Poor technique or muscle weakness may result in a hamstring strainduring the initial stance phase of gait (Hoskins & Pollard, 2005)It is proposed that microscopic damage is caused by the lengtheningof sarcomeres in a non-uniform manner (Brockett, 2004). • Muscle fibres that exhibit short optimal length capabilities are more at risk of microscopic damage (Brockett, 2004).
Clinical Diagnosis Referral of any hamstring distress is vital for establishing correct treatment options and preventing further injury. Diagnosis involves an evaluation of past history, type of action/activity performed and physical examination. MRI scans may be conducted to establish deep- intramuscular strains or tearing of the hamstring . These scans are only performed if a negative response to treatment occurs or the mechanisms of injury are unknown (Hoskins & Pollard, 2005).*Partial tear of right hamstring tendon (red arrows) Source: http://3.bp.blogspot.com/
Clinical Diagnosis The following physical examination techniques are commonly performed when diagnosing hamstring injuriesStraight Leg Raise – Passive leg raise with straightknee.Normal ROM is 80 – 90 .Pain may be reproduced.Comparisons are made between opposite limbs. Source: http://bjsm.bmj.com/Resisted Knee Flexion – Passive resistance aspatient bends knee.Causes hamstring contraction and painStrength of movement is compared to opposite limb(http://www.sportsinjuryclinic.net/) Source: http:// http://www.chiroandosteo.com/
Clinical DiagnosisSlump Test – Determines if any neuralinvolvement is present.Patient straightens out one leg, bends headdownwards and points toes upwards.Stretch is enhanced by pushing patient forward.Symptoms such as pain shooting down the leg is apositive indication of neural involvement. Source: http://www.ihcatl.com/Palpitation – Physician will touch or palpitate themuscle to detect any deformity, pain, tension orhole within the muscle belly and associatedstructures.(http://www.sportsinjuryclinic.net/) Source: http://thump01.pbase.com/
DifferentialSource: http://www.fotosearch.com/ Diagnosis • Misdiagnosis of hamstring strain injuries is common, leading to incorrect management techniques that can exacerbate the injury or prolong the recovery period (Hoskins, 2005). • Preventative techniques to decrease the chance of a hamstring strain are imperative in professional sport. • The sciatic nerve passes through the hamstring muscle group and therefore an injury to the lower back may refer pain to the hamstring region (Noonan, 1999). • Delayed-onset muscle soreness is commonly mistaken as a strain however the symptoms develop 24-72 hours post-exercise then disappear. A strain results in immediate pain and functional deterioration (Noonan, 1999). • Hamstring pain may also be a symptom of other injuries such as adductor strains, sacroiliac joint, gluteal trigger points and bursitis. Source: http://sussexphysio.co.uk/
Phases of Injury and Treatment The following table summarises the 5 phases of injury proposed by Petersen & Holmich (2005) and the appropriate actions to aid recovery Phases of Injury Signs/treatmentPhase 1 (acute): • RICER treatment is important1 - 7days Goal: Minimise swelling, pain and control haemorrhaging. • Use of NSAIDs for short period after injury. • Light movement techniques prevent adhesions.Phase 2 (subacute): • Inflammatory symptoms begin to resolve.3days – 3weeks • Basic exercise techniques promote healing and prevent muscle atrophy. Concentric exercises introduced. • Cardiovascular fitness should be maintained.Phase 3 (remodelling): • Loss of flexibility due to scar tissue formation and pain.1 – 6 weeks • Stretching performed to maintain flexibility. • Eccentric exercise introduced (light to avoid re-injury)Phase 4 (functional): Goal: Decrease the risk of re-injury during sport.2wks – 6months • Sport specific strength and flexibility protocols initiated.Phase 5 (return to comp): Goal: Maintain strength and flexibility of muscle to avoid3wks – 6mths recurring injury.
Rehabilitation Once a qualified physician has established a correct diagnosis, there are a variety of techniques used to enhance recovery and prevent further injury. Stretching techniques are outlined below: STATIC STRETCHING CONTRACT – RELAX Internal rotation External rotation STRETCHING DYNAMIC STRETCHINGSource: Swinging of leg forward and backwards with gradual(http://www.sportsinjuryclinic.net/) increases in height
RehabilitationA study by Malliaropoulos et.al (2004), examined two differentrehabilitation protocols to determine effectiveness of each.80 athletes with acute hamstring strain injuries were assessed, withrehabilitation occurring 48hrs post-injury.One group performed one session daily and the other participated in fourper day.Each session involved a static hamstring muscle stretch that wassustained for 30 seconds. This was performed 4 times per session.The results indicated that the group which participated in the greaternumber of sessions (4 per day) were able to regain ROM in a shorterperiod of time and therefore spend less time away from competition.
Rehabilitation and Injury PreventionOther forms of rehabilitation and injury prevention forhamstring injuries include: • Sports Massage • Acupuncture • Taping techniques • Compression Shorts • Bracing •Yoga and Pilates
Literature Review(Evidence based prevention of hamstring injuries in sport.Petersen & Holmich, 2005)• Age, physical status, type of sport, exercise techniques and warm-up strategies are important elements used to predict the likelihoodof a hamstring injury.• A lack of clinical evidence exists regarding the effectiveness ofhamstring rehabilitation methods. However immobilizationthroughout the recovery phase of injury is known to have a negativeimpact on healing (Morgan & Allen, 1999).• There is a high incidence of recurring hamstring injuries especiallyif inadequate rehabilitation and/or an appropriate warm-up is notperformed before physical activity.• In the AFL, research suggests that each club experiences 5-6hamstring related injuries per year. This amounts to 15-21 gamesmissed per season (Brockett, 2004).
Literature Review• The biarticular arrangement of the hamstring muscle groupprovides a substantial risk of injury especially due to poorbiomechanical techniques and/or muscle weakness.• Studies suggest that the period of change from an eccentric to aconcentric contraction is most susceptible to strain injuries.• Studies have shown that fatigue has a major influence regardinginjury risk. An investigation into English professional footballshowed that a significant number of hamstring injuries occurred inthe latter stages of each half (Askling et.al, 2006).• Hamstring strength , flexibility exercises and the presence of painshould be used to determine when an athlete can return tocompetition.
ReferencesAskling, C., Saartok, T., & Thorstensson, A. (2006). Type of acute hamstring strain affects flexibility, strength, and time to return to pre-injury level. British Journal of Sports Medicine, 40(1):40-44.Brockett, C., Morgan, D., & Proske, U. (2004). Predicting hamstring strain injury in elite athletes. Medicine and Science in Sports and Exercise, 36(3): 379-387.Hoskins, W., & Pollard, H. (2005). The management of hamstring injuries – part 1: Issues in diagnosis. Manual Therapy, 10(1): 96-107.Malliaropoulos, N., Papalexandris, S., Papalada, A., & Papacostas, E. (2004). The role of stretching in rehabilitation of hamstring injuries: 80 athletes follow-up. Medicine and Science in Sports and Exercise, 37(1): 756-759.
ReferencesMorgan, D., & Allen, G. (1999). Early events in stretched-induced muscle damage. Journal of Applied Physiology, 87(1): 2007- 2015.Noonan, T., & Garrett, W. (1999). Muscle strain injury: Diagnosis and treatment. Journal of American Academy of Orthopaedic Surgery, 7(1): 262-269.Orchard, J., Marsden, S., & Garlick, D. (1997). Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers. American Journal of Sport Medicine, 25(1):81-85.Petersen, J., & Holmich, P. (2005). Evidence based prevention of hamstring injuries in sport. British Journal of Sports Medicine, 39(1): 319-323.Sports Injury Clinic. (2009). Hamstring Strain Rehabilitation. Retrieved April 29, 2009, from http://www.sportsinjuryclinic.net/cybertherapist/back/hams trings/hamstringstrain.htm