Epidemiology FA Audit of Injuries study found that 12% of all injuries reported over two seasons were hamstring strains. (Woods Br J Sports Med 2004;38;36-41) 11-15% Cricket (Stretch 2003, Orchard et al 2002a) 16% AFL with a recurrence rate of 34% Seward et al (1993) Incidence 0.30 per 1000 playing hours with average severity of 17 days absent in English Rugby Union – Brooks et al (2005)
Epidemiological evidence suggests that hamstring strains are associated with eccentric load, where the contracting muscle is lengthened and there may well be a lack of neuromuscular control. Biggest risk of injury is previous injury Biceps femoris most commonly injured Increased incidence with age Epidemiology
Less Common Posterior thigh pain Referred from SIJ Tendinopathy Bursitis Compartment syndrome Apophysitis Nerve entrapment Adductor magnus Myositis Ossificans
Not to be missed Tumors Iliac artery insufficiency
Diagnosis Listen Hx is key Look Move Feel Special tests
Neural Dynamics Slump test as a diagnostic tool Slump as a treatment modality Significant effect on Fascia – Vleeming et al 2005
Lumbar Spine Age / Degeneration of L4/5 and L5/S1 associated with prevalence of hamstring injuries Successful management of hamstring injuries in Australian Rules footballers: two case reports Chiropractic & Osteopathy 2005, 13:4 doi:10.1186/1746-1340-13-4
If your think the lesion is soft tissue Dynamic Ultrasound or MRI are you investigations of choice
Common mechanism Late swing phase in running action Eccentric contraction to decelerate the shank Often accentuated in preparation to jump, kick Trunk flexion whilst running (Verral, 2005)
Other mechanisms Stretch with knee fully extended (stretching for a ball, kicking) Forced trunk flexion with foot planted (waterskiing)
Possible causes of Muscle Injury Musculoskeletal imbalances Poor muscular co-ordination Inappropriate training Fatigue Incomplete rehabilitation Repeated micro-trauma
Musculoskeletal imbalances Any breakdown in the effective function of the legs and pelvis during running may predispose to injury. Examples include: postural changes due to muscle tightness lumbar or sacro-iliac joint stiffness poor co-ordination of movement or early fatigue associated with muscle weakness leg length discrepancy (LLD) which will affect pelvic motion and stride length. Note: LLD < 1.5 cm is usually not significant prolonged or delayed pronation or supination of the foot, which will alter the function of the leg and pelvis during the running cycle Intrinsic and extrinsic factors
Poor muscular co-ordination Running requires strength, power, endurance and co- ordination. Problem-free running cannot take place if the hamstrings are weak, inflexible, or if there is poor neuromuscular co-ordination. Loss of the normal ratio of muscle power between the quadriceps and hamstrings may also occur. The normal quadriceps/hamstrings ratio is 60:40. Loss of the normal ratio may be due to excessive development of the quadriceps, or due to existing weakness of the hamstrings. A normal ratio is essential to prevent imbalances from occurring during the running cycle. Intrinsic and extrinsic factors
Inappropriate training “Inappropriate” comprises all the factors that may affect your body’s ability to adapt to the varied stresses of running. Factors include: excessive mileage rapid increase in mileage inadequate warm-up and cool-down poor stretching cambered running surfaces worn shoes or orthotics
Fatigue Fatigue affects performance and may predispose you to injury. At a physiological level, fatigue may be reflected in a prolonged recovery time at neuromuscular junctions, which diminishes effective muscle activation, slows the clearing of metabolites from the muscle, and impairs the ability of the muscle to contract. Fatigue therefore results in decreased strength, power and endurance, and will increase the risk of injury.
Incomplete rehabilitation As runners, we are always eager to get back on the road as soon as possible. If an injury is not properly treated, or if you do not achieve your pre-injury levels of strength, endurance and flexibility, the risk of re-injury is increased. Effective rehabilitation (which means putting in the time with the physio, or at the gym) will allow you to get back on the road and stay there.
Repeated micro-trauma Often trauma to the hamstrings may not always be significant enough to cause pain or disability at the time of injury.The reduction in hamstring function may be so gradual that it will not be detected until there is a serious problem. This is often described as “the last straw that broke the camel’s back”, where repeated micro-trauma will finally result in pain and dysfunction. When running, the hamstrings are often exposed to repeated micro-trauma due to over-striding, as well as with a change of pace. Over-striding, particularly when just starting to run downhill, places the hamstrings under excessive eccentric load as the muscle works to stabilise the knee joint. The excessive eccentric load may result in micro-trauma to the muscle fibres, leading to injury.
Muscle Injury What are the consequences to the athlete of not treating a muscle injury correctly? How much damage is caused by inactivity on the athletes and the doctors part? Why is there no/little consensus on management of muscle injury?
Staring point with an Hamstring lesion R.I.C.E Compression the key Gentle mobilisation Partial weight bearing as tolerated Electrotherapy modalities When to stretch? When to start running again?
Continued Rx STR / MFR Acupuncture NSAIDs after 24 hours Electrotherapy modalities Correct Physical rehabilitation is paramount in the management of hamstring injuries
Early mobilisation versus strength/stretching Two rehabilitation programs Static stretching and progressive strengthening Progressive agility and lumber stabilisation program No stat difference in RTS times Stat difference in recurrence rates over I year period remain ISQ ( Sherry et al, 2004. JOSPT, 34(3): 116-25)
Where basic science and clinical guidelines collide Perception is that early mobilisation is against basic principles. RICE principle for 7 days minimises pain, swelling to offer best possible conditions for healing process. Kannus et all (2003) Studies cited were for non-contractile tissues (ie ligaments) Prolonged immobilisation is detrimental Early mobilisation of affected tissue increases density of scar formation. (Jarvinen, 1975) What about remodelling???
Accelerated running program Developed by Graham Reid Australian Hockey Physio Injured player on tour Captive audience Good result
Accelerated Running Program Day 0: Ice, Electro modalities, +/- CPM, +/-Ice, Compression etc Day 1: Continue as above. When range in sitting position (Lordotic spine) at 120 or - 10 degrees off full knee extension ? start running program
Progressive Running Program Graham Reid Jogging at variable speed up to 75% Minimal acceleration/deceleration Approx 4 min/km pace Up to 2 kms Variable distances 100mx3, 90mx3, 80mx3, 70mx3, 60mx3, 50mx3, 40mx3, 30mx3: Repeat x 2 Backwards running: 50 x 3, 75 x 6, 40 x 3
Progressive Running Program Graham Reid Once at 75% without pain, start acceleration program 40 – 20 –40 35- 20 –35 30-20-30 25-20-25 20-----20 15-----15
Summary of running program Aggressive but controlled rehab Takes out a lot of the guess work with training loads Many variations – needs to be tailored to the sport and then the individual athlete Addressing causative factors is the most important aspect to hamstring rehabilitation
My approach to pre running criteria (how do you know when the athlete can run ????) Adductor magnus bridges 5 sets of 12 reps Seated knee extension = 10 degrees off straight Single leg long level bridge = pain free
Why does early mobilisation work? Eccentric exercise in a controlled way is functional Improved neural patterning/technical ability Allows progression as quickly as possible with consistent feedback CPM effect- decreases disorganised collagen formation. Maintain extensibility of the muscle Hamstring strains are almost never isolated strains Strengthening in a functional way
Recurrences Scar at its weakest point 10-12 days after injury Time frames will vary - forced by time constraints Analogous to ACL return at 6 months
Eccentrics??? ConcentricEccentric Characteristics of eccentric contraction Produces more force than concentrics Selectively recruits Fast fibers. Fast fibers are bigger and have greater potential for growth than slow fibers. During the eccentric phase of movement, the muscle absorbs energy. This work is done “by stretching the muscle and in this process the muscle absorbs mechanical stress This mechanical energy is dissipated or converted into one or a combination of two energies. 1. Heat 2. Elastic Recoil
Key concepts in injury prevention Improve the training regime so that it more accurately reflects sports specific conditions with the goal of improving muscle conditioning; Try and improve fatigue resistance of the hamstring muscle Try and induce a change in the viscoelastic properties of muscle so as to increase energy absorption and decrease load on the muscle-tendon unit for any given length especially in body positions of function and vulnerability to injury. Verrall et al 2005 Br J Sports Med
Can we predict/prevent hamstring strains? Previously injured muscles developed peak torque at significantly shorter range than uninjured muscles Peak torque and quad / hamstring torque ratios were not significantly different Eccentric exercise possibly shifts length-tension curve to the right Most Studies used concentric measurements, Why when we know hamstrings have an eccentric action? ( Brockett et al, 2004: Med Sci Sports & Ex. 36(3))
Predicting/ Preventing muscle strains Role of screening Hamstring range Strength components (Isokinetic) Joint ranges Traditionally, our biggest predictive factor to hamstring strains is previous history of hamstring strain.
Can we predict/prevent hamstring strains? Decreased incidence in soccer players on an eccentric program Askling et al (2003): Scand. J. Med. Sci. Sports 13: 244-250 Decreased hours lost, no of injury and weeks out with intervention program (Verral, BJSM 2005)
Incremental Increase in Eccentric Exercise Drop-catch exercises (Stanton and Purdam 1989 J Orthop Sports Phys Ther) Nordic hamstrings High-velocity eccentric exercises in the final phase of rehabilitation (Geraci 1998)
Points to consider in Footballers Body awareness Requirements of the Sport Limited neural aspects Limited kicking etc. till full running Ball work restricted in initial stages Physical rehabilitation does not replace intensive hands-on approach How to integrated this philosophy with the football management
Sports Specificity relating to hamstring injury prevention Think specific and generic ie Football Ladders Change of direction Backwards/sideways running Shuttles Chase and escape drills Recreate load, stress, strain, joint angles, fatigue index
Case Study Primary hamstring lesion grade 1+ on US Day 1 PRICE crutches 2/7 no NSAIDs Day 3 STR / PNF local electrotherapy + NSAIDs Seated SLR / passive mobilisations Day 5 program Active mobilisations / basic gym program Day 7 Hamstring specific program (powerpoint)
Case Study Contd Day 14 Re US scan good reduction in fluid RTP day 18 Post injury S&C lead eccentric program in place and a physio lead pelvic neuromuscular patterning program with monitoring
Summary Diagnosis is key, use correct imaging modalities Initial treatment is in line with any other soft tissue injury; protection, RICE and early mobilisation. Understand that there is close relationship between hamstring injury, the neural system and lumbar spine pathology
Summary continued Accelerated running programs can be utilised Identify predisposing factors relating to the hamstring injury in that individual athlete Apply an eccentric injury prevention strategy Develop your own strategy related to current research evidence Be sports specific in your approach
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