A 26-year-old professional footballer first sustained an injury to his right hamstring when sprinting during a match. Clinically and radiologically he presented with a grade 2 biceps femoris musculotendinous junction strain (figure 1). Intermuscular haemorrhage tracking around the sciatic nerve was noted.
Past injuries included left adductor strain 18 months prior; left soleus strain 18 months prior; left proximal hamstring tendinopathy 17 months prior; right knee grade 3 medial collateral ligament (MCL) tear 16 months prior; right Achilles reactive tendinopathy onset 8 months prior and left adductor strain 6 months prior.
RICE followed by soft tissue massage, stretching, core strengthening, progressive agility and neuromuscular control exercises, a graded running programme and an isolated hamstring strengthening programme with specific emphasis on eccentric exercises. He returned to full-team training (RTT) 21 days postinjury, RTP 30 days postinjury and then played the next three games without incident.
Two days after his third game, when the player was walking, he experienced a gradual onset of posterior thigh pain. Clinically, he presented with a grade 1 hamstring strain that was MRI negative. He RTT 7 days postinjury and RTP 16 days postinjury, playing a full game without incident. The player then went on holiday for a month which involved long periods of travel, sustained sitting and minimal exercise.
On returning to preseason training, he complained of 'tightness' in his right hamstring from the second day of training, worsening until day 5 when he was withdrawn from training reporting more intense discomfort after kicking a ball in shooting for goal. Clinically, he presented with a grade 1 hamstring injury that was confirmed on MRI (figure 2) to be more medial, towards the epimysium and not continuous with the scar tissue from the initial injury.
Given the player's history of lower back pain, symptoms of 'tightness' on the right side and a feeling of general restriction throughout the lumbar spine, an epidural corticosteroid injection was performed at L4-5 followed by 2 days of complete rest from physical activity.
Postinjection the player reported a general improvement in his feeling of 'freedom' on the right side and felt able to swing his legs through fully into hip flexion when running for the first time since the onset of hamstring stiffness on return to preseason training. However, following a long drive (>3 h) 5 days later he reported a return of his posterior thigh and lumbar spine restriction. He was treated similarly to the initial injury, RTT 10 days postinjury and RTP 21 days postinjury, playing a full preseason friendly game without incident.
Five days later he started another pre-season game. After 5 min, he sprinted with the ball and crossed the ball with a whipping action and immediately felt some tightness in his hamstring, without an associated feeling of tearing or pain, and was thereafter unable to sprint with confidence. He left the pitch and again presented clinically with a grade 1 injury. Subsequent MRI was reported as a small grade 2 injury (figure 3). This injury was again within the long head of biceps femoris muscle, at a similar level, but not continuous with the site of any previous injury.
After this fourth episode the player underwent a more prolonged and intensive rehabilitation which included progressions based on the percentage of normal running activity in a game (accelerations, repeated efforts, total distance and high-speed distance). The strength programme had an even greater bias on eccentric hip and knee dominant hamstring strength exercises. He RTT 25 days postinjury and RTP 34 days postinjury as a substitute coming on late in the game. Despite extensively warming up prior to joining the play, after 2 min he accelerated at medium intensity and felt some hamstring pain. He played the few remaining minutes but was unable to sprint. Clinically, he presented with a grade 2 strain but MRI showed only a small myofascial tear (figure 4). The player had completed a full week's training prior to this game including repeated maximal sprinting and match play situations at full intensity.
At this stage, the player had sustained five hamstring injuries in 5 months, none very severe clinically, all of which had undergone a routine yet comprehensive rehabilitation and graded RTP programme that had been successful with other players.
Table 1 summarises the episodes of hamstring injury.
Between the fifth episode and RTP, a number of additional investigations were performed, including a standard lumbar and posterior thigh MRI; an upright lumbar MRI with standing, sitting and lumbar flexion views and nerve conduction studies, all of which were normal. Isokinetic assessment was conducted 22 days after the final episode using a Biodex 3. After familiarisation, the player completed five maximal efforts of concentric knee flexion and extension from 0  to 90  knee flexion at 60 /s. The results demonstrated right hamstring strength>left (142 Nm vs 128 Nm, 10% asymmetry); right H/Q ratio<left (0.57 vs 0.62) and right peak torque angle>left (24  vs 23 ).
The clinical challenge was to identify and address any possible factors that may have contributed to the recurrences, and to review and modify the rehabilitation programme accordingly. Potentially relevant risk factors and modifiable hamstring muscle properties are noted in table 2.
It was decided early in this injury management to prolong the rehabilitation period to enable a higher volume of intervention and loading. Given the lack of evidence on known univariate risk factors, we investigated a range of other issues that the available evidence and our collective clinical experience suggested may be contributing to elevated risk of reinjury.
A biomechanical assessment included review by a sports podiatrist. Significant findings included asymmetrical ankle joint dorsiflexion (L=7.5 cm vs R=9 cm on dorsiflexion lunge testing)  and a positive Trendelenburg sign on the right side with associated internal femoral rotation on treadmill gait analysis. Pelvic assessment was suggestive of a slight anterior rotation of the right ilium with associated functional leg length discrepancy (left approximately 5 mm longer than right).
The player was fitted with custom-made semirigid orthotics to address the 5 mm leg length discrepancy. They were worn in both trainers and football boots from the start of the rehabilitation programme. Specific hip abductor and lateral trunk strengthening exercises were increased into his programme.
Osteopathic manual therapy was started aiming at achieving a sustained resolution of the anterior tilt of the right ilium. Initial manipulation of the ilium was performed by an osteopathic specialist in Germany. Further sacroiliac joint (SIJ) manipulation was undertaken on a weekly basis and combined with specific stretches of the posterior chain. Other manipulations performed included right anterior astragalum (anterior-external position), anterior fibula head, internal hip, anterior iliacum and horizontal sacrum, T11-L2, T7-C1 level and first rib (right side) and occipital-C1-C2.
Although adverse neurodynamic signs were not objectively identified clinically or radiologically:SLR and slump test had at all times been consistently equal and within normal ranges as were repeated normal lumbar MRIs:the player continued to complain of symptoms consistent with a neural contribution to his presentation. Relevant complaints included prolonged sitting, especially while driving, causing numbness and aching in the right buttock and posterior thigh. The player also complained of a 'general restriction' in the right side during swing phase of high-speed running and kicking, and an asymmetrical feeling of heaviness on the right side when fatigued. These symptoms were addressed in two ways.
The first epidural (L4/5) resulted in an immediate resolution of these neural symptoms. However, the player felt that the effect wore off after 4-5 days which coincided with a long car journey in which the player had been sitting for 3 h. It is unclear whether the effect of the epidural had indeed worn off rapidly, or if it had been mechanically counteracted by sustaining the provocative sitting and flexed position. Due to the initial success of the epidural and unknown influence of the prolonged sitting and flexion on negating its effectiveness, a second epidural was performed between the fourth and fifth episodes, with a more prolonged rest period followed by strict instructions on avoiding any periods of prolonged sitting.
The initial rehabilitations included mobilising the neural structures within the posterior thigh via sliding techniques complemented by mobilising and releasing areas along the course of the sciatic nerve. This included passive accessory mobilisation and manipulation of lower lumbar segments, manual release and stretching of the hip rotators, intermuscular mobilisation of the hamstring muscle group and mobilisation of the proximal tibio-fibular joint due to its close proximity to the common peroneal nerve.
As these techniques were components of the previous failed rehabilitations, a more aggressive neural mobilisation approach was started incorporating an SLR-biased technique sensitised with internal hip rotation, adduction and dorsiflexion. This was applied daily with a dosage of 3x10 repetitions.
The player's core stability programme was redesigned. The programme included a combination of global core type exercises; control exercises with an emphasis on transversus abdominis and internal oblique recruitment and reformer-based Pilates exercises with the aim of combining lumbopelvic control with dynamic recruitment of the hip extensors and hamstring muscles. The player continued to participate in the squad injury prevention programme, a multistation session conducted twice per week before training. These sessions comprise a circuit of proprioceptive, neuromuscular control, core stability/strength and a varied lower limb strength exercise.
Core strengthening was supplemented using Document Based Care (DBC; www.dbc-clinic.com) core strengthening machines which have been designed to isolate the specific muscles involved in trunk core stability through a series of specific loaded exercises incorporating the main global lumbar movements (extension, rotation, flexion and side flexion) while limiting movement and activity in the muscles around the hips and thoracic spine. Exercises on the DBC machines were completed every other day from week 2 of the rehabilitation.
Eccentric strengthening should form an essential part of any hamstring rehabilitation programme  and the player was exposed to this early in all the rehabilitations. Initially, this was in the form of manual eccentric strengthening exercises completed prone on the plinth in three sets of six repetitions with maximal pain-free effort. From week 2, the player completed a 1-in-3 day-strength programme which included both hip and knee dominant hamstring exercises. The programme included double and single leg reverse dead lifts, Nordic hamstring exercises with variations of hip angle, high box step ups, YoYo flywheel hamstring exercises and slide board hamstring curls in a bridge position.
In the final 'failed' rehabilitation, the player completed 11 strength sessions; in the latter rehabilitation the number of strength sessions was similar (12) with a similar volume of eccentric strength exercises. The significant difference was an increase in the number of exercises which focused on faster speed of contraction at longer hamstring muscle lengths such as drop lunges (hip dominant) and single leg cable sprinter kick outs (knee dominant).
Hamstring rehabilitation protocols typically involve incremental progression of running speed with supplementary conditioning when appropriate. The total running and non-weight-bearing training load is usually progressed based on standard weekly training distances and high-speed running intensities. During the player's previous HMI, this type of running progression was administered, with the player RTT after completing various objective assessments.
Running load was significantly increased during this latter rehabilitation. The programme was designed to overload the player with high-speed running to provide greater exposure to excessive eccentric loads during this specific movement. It comprised eight sets of 3 day cycles with consecutive days of running followed by a day of 'off legs' conditioning (pool training). The first of the two running days was progressed over the 24-day period based on both the maximum running speed and the player's individual training and match high-speed running and accelerations/deceleration requirements.
The second of the two running days was a submaximal running session based on the player's maximal aerobic speed (MAS). This session (4x8x100 m at 120% MAS or 6 m/s) was, therefore, conducted eight times and this not only improved the player's aerobic running power but also served as a regular fitness test. As the session was standardised, close heart rate (HR) and Heart Rate Variability (HRV) monitoring determined the player's adaptation to this standard protocol during the rehabilitation.
Table 3 demonstrates the programme.
The programme was monitored using GPS tracking which provided data on variables including total distance, number of high-speed efforts, high-speed metres and accelerations/decelerations during training sessions. In conjunction with video-based tracking of matches (Prozone), this provides an objective measure of each player's 'standard week' in terms of training and match loads. From this standard week incremental load percentages can be calculated.
The player consulted an international physician 5 days after the last episode. The physician concluded that this HMI was not serious and that abnormalities in the lumbar region were contributing to the reinjuries. He injected a number of sites with local anaesthetic followed by a mixture of Traumeel and Actovegin. Injections were performed in the lumbar regions centrally, over the facet joints and the iliolumbar ligaments bilaterally and the right SIJ. Three similar injections were administered into and adjacent to the HMI site.
The player started regular sessions of yoga-based stretching and relaxation with a qualified DRU yoga instructor. These consisted of DRU fascial warm-up techniques; intense hamstring and low back stretches; guided DRU relaxations and DRU breath training (techniques to improve lung capacity, stamina and to activate the relaxation response through the body). Sessions were undertaken for 60 min twice per week. The player soon reported subjective improvement in his hamstring freedom.
The player RTT 33 days postinjury and was deemed available for selection in 39 days. He then RTP 42 days postinjury. He played 33 out of a possible 42 games until the end of the season. He missed seven games with a ruptured plantaris but did not miss any due to hamstring problems. He continued this treatment regime at maintenance level during this period.