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Neurogenic hamstring and calf pain in football. When is a tear not a tear?

By Dr Simon Petrides MB BS DO DM-S Med Dip Sports Med PGCert FFSEM (UK&I)

Musculoskeletal & Sports Physician

Blackberry Clinic Group

Hamstring and calf injuries or strains are one of the most difficult conditions to treat in sports medicine. They are especially common in footballers but also found in the general population due to an increase in activity levels. The aetiology behind hamstring and calf injuries continues to be confusing and inconclusive for both medical practitioners and researchers. The fact that these injuries frequently reoccur suggests that ineffective management may be part of the problem. It is a common occurrence for football player to be removed from play with a suspected hamstring or calf tear with subsequent MRI and ultrasound studies proving inconclusive or showing no injury to the muscle.


Hamstring injuries account for 12% of the total injuries, with an average of five per club per season, resulting in 15 missed matches and 90 missed training days. This figure demonstrates the significant effect on the footballing population of this type of injury.

Vad et al in 2000 found that the majority of these hamstring injuries may be due to neurological problems arising from the central nervous system. Inflammation and irritation of the nerve roots exiting the vertebral foramen of the lumbar spine may in fact cause increased basal tone of the hamstring muscles or abnormality in timing of contraction making them more susceptible to injury.

A study by Kornberg and McCarthy in 1992 found that there was a high incidence of positive slump tests (a method of testing the tension of a nerve) in a group of injured football players compared with a control group. Research suggests that this abnormal neural (nerve) tension or neural tethering may be responsible for the symptoms associated with 'neurogenic hamstrings.'

It has been proposed that these neural influences may predispose select groups of athletes to hamstring pain of neurogenic (nerve) origin, particularly those who engage in track and field sports as well as footballers. For this reason, athletes and many elite footballers face ongoing problems with continued high-level training and competition.

What can be done?

Caudal Epidural Steroid Injection (ESI)

Although ESI therapy is a relatively new method used to treat hamstring injuries of neurogenic origin, there are clinics in the UK offering this as an option for treatment of hamstring and calf pain. Sports injury, musculoskeletal and pain management specialist doctors are able to administer these injections, preferably under fluoroscopic guidance.

Corticosteroids commonly used for their anti-inflammatory properties are injected into the epidural space surrounding the spinal nerve or the articular facet near where the nerve root traverses. The aim is to reduce neural sensitivity, which may help return hamstring muscles to a normal resting tone and/or reduce any referred posterior thigh pain.

Physical Therapy and Rehabilitation

It is suggested that an extensive post-epidural programme needs to be implemented to ensure thorough rehabilitation and to address the risk factors for recurrence that have been identified. These programmes are implemented by specialised physiotherapists, chiropractors or osteopaths.

Research has highlighted that players with low back pain or sacroiliac joint dysfunction can suffer increased hamstring torque. Therefore, it is suggested that epidural steroid injection, combined with treatments administered by a physiotherapist, chiropractor or osteopath, may have a role to play in preventing and treating hamstring and calf injuries.

More awareness of recent research would enable doctors and practitioners to utilise their skills appropriately to provide the highest quality of care in management of these recurrent hamstring and calf injuries.

Prevention of recurrence

Despite biomechanical asymmetry and dysfunction being addressed by the team physios or osteopaths, there are some football players who persistently challenge the medical team by suffering repeated hamstring or calf tears. These may respond to epidural steroid injection, but those that recur may need an assessment of lumbar stability using 'dynamic fluoroscopy' followed by prolotherapy injections of hypertonic dextrose targeted at the involved spinal segmental level.


Prolotherapy as an injection treatment has been used for musculoskeletal pain in several different forms for almost a century. George Hackett, an American surgeon, initially used the technique on hernias and subsequently developed some of the musculoskeletal protocols used today.

Prolotherapy has become an accepted intervention in the UK for a variety of musculoskeletal complaints, including back pain, despite its controversial 80 year history and failure so far to enter mainstream practice. This is not because of the lack of research or reasonable proof of its safety and efficacy but more likely due to its development outside the NHS since the profession of Musculoskeletal Medicine is not widespread as a career pathway within the current NHS system.

Prolotherapy injections are used in the UK, USA, Australia and New Zealand for a broad range of sub-acute and chronic recalcitrant musculoskeletal disorders. Although evidence for its effectiveness is reported to be inconclusive, anecdotal evidence of success has maintained the profile of this increasingly popular treatment. Evidence based medicine demands that clinical trials demonstrate the effectiveness of medical interventions but all back pain research is fraught with methodological difficulties.

A plethora of literature does exist analysing the effectiveness of prolotherapy in low back pain.

Other forms of prolotherapy include: autologous blood injection, platelet rich plasma injection, autologous conditioned plasma injection, dry needling and stem cell therapy.


There are two major classes of proliferants commonly used in dextrose prolotherapy:

Irritants such as phenol which act by either damaging cells directly or by rendering the cells antigenic through alteration of surface proteins.

Osmotics such as glucose/dextrose and glycerine. These act by causing an 'osmotic shock' to cells thus resulting in the release of pro-inflammatory substances.

Three different solutions with different modes of action are in use in specialised centres in the UK:

Hyperosmolar dextrose (12.5-25%) which causes osmotic damage to cell walls triggering release of inflammatory mediators.

Dextrose/glycerol/phenol mixture 'P2G'- an osmotic and cellular irritant.

The resulting strengthening of collagen fibres is presumed to have a stabilising effect on the intervertebral segments, improving mechanical function and thus reducing pain.

5% Dextrose is gaining popularity in 'Neural Prolotherapy' by acting as a neuromodulator and may also be of use in neurogenic hamstring and calf pain.


The indication for spinal prolotherapy is commonly for subacute, chronic or recurrent axial or referred pain. Clinically determined (as well as functional/radiological) instability can respond well to prolotherapy. The diagnoses in which prolotherapy is known to help are diverse but they all correlate with the theme of inadequate spinal or peripheral joint support mechanisms.

Lumbar instability

Although there is no 'gold standard' test to identify lumbar instability, the concept has been studied widely and several definitions have been proposed. Panjabi stated that instability is defined as:

'A significant decrease in the capacity of the stabilising system of the spine to maintain the intervertebral neutral zones within the physiological limits so that there is no neurological dysfunction, no major deformity, and no incapacitating pain.'

Structural/radiological lumbar instability:

Several radiographic criteria have been proposed as indicators of lumbar intervertebral instability and the topic remains controversial. Flexion/extension radiographs and more recently videofluoroscopy have been used in assessment.

Instability measurements may be different at each level of the lumbar spine. Panjabi proposed that sagittal rotation range of more than 15 degrees existing at L1-4, 20 degrees at L4/5 and 25 degrees at L5/S1 were more relevant.

Functional lumbar instability

Functional lumbar instability is determined by 3 subsystems:

1) The 'Passive stabilising system' includes the vertebrae, ligaments (supraspinous, iliolumbar, interspinous, posterior/anterior longitudenal, ligamentum flavum), discs, joint capsules and facet joints. The passive stabilisers are effective at the limits of the neutral zone and into the elastic zone.

2) The 'Active stabilising system': this includes the tonic (transversus abdominis and multifidus) and phasic (external oblique, erector spinae, rectus abdominis).The active stabilisers are effective within the neutral zone.

3) The 'Neuromuscular system': this coordinates the timing, balance, magnitude and control of all movements through proprioceptive afferent input from mechanoreceptors with output producing muscle activation depending on need. Poor control may explain why LBP can occur without significant load.

These three subsystems are functionally interdependent. Many players have been expertly managed by experienced physical therapists such that the 'active' and 'neuromuscular' systems have been optimised. Prolotherapy can play an important role in augmentation of the ligamentous component of the 'passive' subsystem such that not only do the ligaments exhibit increased size and strength (narrowing the neutral zone), but they also allow earlier firing of mechanoreceptors enabling the 'active and 'neuromuscular' systems to control movement more finely within the neutral zone.

Diagnostic features of lumbar instability:

History: Apart from recurrent posterior chain injury, features on direct questioning which suggest lumbar instability include: episodic LBP and episodes of the back 'going out', pain on prolonged postures, pain on transition from sitting to standing, diminishing effectiveness of manipulation and episodic sacroiliac dysfunction or sacroiliac hypermobility.

Examination: Clinical tests of instability in regular use include:

The prone instability test: The patient is prone with the upper torso on the couch and the feet on the floor. The practitioner performs passive intervertebral motion testing. The patient then lifts his legs just off the floor and passive tests are repeated. The test is positive when the patient reports pain before the leg lift and no pain after. It is assumed that lumbo-pelvic stabilisers contract to stabilise the segment. This test can also be helpful in the fully prone position.

The passive lumbar extension test: The patient is prone and is asked to keep the knees extended whilst the practitioner lifts the legs 30 cm above the couch and exerts a small amount of traction. Reproduction of pain is a sign of a positive test. When measured against radiological evidence of instability the sensitivity of this test is 84.2% and the specificity 90.4%.

Motion palpation tests: Passive Accessory Intervertebral Motion (PAIVM) tests, and Passive Physiological Intervertebral Motion (PPIVM) tests are used in varying degrees by many different manual therapists.


The following investigations can contribute to the holistic evaluation of the patient with suspected instability when considering whether prolotherapy may be a relevant approach in recurrent posterior chain injury:

MRI and CT scan: existence of degenerative disc and facet joint disease is not in itself diagnostic of instability but can help in the work up of a patient in whom instability is a possible diagnosis. For example, minimal listhesis or sagittal translation along with disc degeneration with modic changes and/or an annular tear can be indicative of an unstable segment.

Flexion /Extension radiographs: have been described above, measurements of sagittal rotation and sagittal translation can help to implicate levels that may be symptomatic.

Videofluoroscopic kinematic analysis: According to one author, abnormalities in 'how' the motion occurred in midrange (rather than total range) seems to be associated with LBP. The variables used in this study described a disruption in the rate of attainment of angular or linear displacement during midrange postures. Assessments can be made of extent of movement along with quality and sequencing of movement.

Protocol for prolotherapy injections:

Small volumes of a solution containing hyperosmolar dextrose or a solution called P2G (25% dextrose, 25% glycerol and 2% phenol) are injected around ligamento-periosteal junctions, teno-osseous junctions or into joints. A common proliferant injectate used in the UK is a 50/50 mixture of P2G and 1% lidocaine. A weaker solution that can be used is 50% dextrose diluted with 1% lidocaine to form a 12.5 – 25% dextrose solution.

Prolotherapy is usually performed on 3 occasions initially with 1-3 weeks between each treatment. A further course of 3 treatments is used if the first course is subjectively or objectively helpful on a Visual Analogue pain Scale (VAS) and/or an Oswestry Disability Index (ODI) but if the improvement is incomplete.

Verbal or written consent is obtained, then with the patient in the prone position injection is made onto thirteen sites under fluoroscopic x-ray guidance around the L4/5 and L5/S1 intervertebral segments. In the UK most practitioners use 5mls P2G mixed with 5 mls of lidocaine 1% or a solution of dextrose with lidocaine.


There is frequently a flare of pain for 1-2 days after the injection and patients are warned about this. They are asked not to take NSAIDS for the duration of the course of treatment.

Research shows that best results for back pain are when the course of injections is accompanied by active rehabilitation and advice on self-management.

Footballers are advised to return to the pre injection comfortable level of training after 2 days.


A post injection flare of pain is common but will last only one to three days. These flares usually respond to simple analgesia such as paracetamol or co-codamol. NSAID use is to be avoided if possible.

Adverse events:

Risk of allergic reaction, infection and nerve damage is very low. Injections should only be performed by doctors trained in the technique and in a controlled environment whilst using sterile techniques. Although P2G is not licensed for use in the UK, this does not prohibit its use and it has not been reported to cause significant side effects or adverse reactions. A survey in 2006 concluded that adverse reactions or events were no more common in spinal prolotherapy than in other spinal injections. There have been no significant adverse reactions from peripheral prolotherapy procedures.


Prolotherapy has been used in its current form for almost a hundred years with hundreds of published articles, meta-analyses and a handful of randomised controlled trials. These studies stand out with low 'risk of bias' in that proliferant solutions such as dextrose, P2G and autologous blood have no pharmaceutical patent and consequently the studies do not attract corporate finance. The safety and efficacy of the treatments account for their advancing popularity in the western world.

In view of the reluctance of establishments to promote high quality research into the technique of prolotherapy, it may remain 'one of musculoskeletal and sports medicine's best kept secrets' for a few more years to come.


Whilst injections remain a useful option for the management of this condition, it is important that the multidisciplinary team work together to ensure an integrated approach focussing on lumbopelvic and hip stability along with posterior chain strength and flexibility. Functional approaches including neural mobilistation, muscle balance and proprioceptive exercises should all run concurrently to optimise the likelihood of a speedy recovery.


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