BRINGING SCIENCE TO TREATMENT

Intramuscular hamstring tendon injury: prognosis, surgical repair and rehabilitation

Adam Smith explores the anatomy of intramuscular hamstring tendons, outlines an injury classification system and using a case study, provides treatment and rehab options following surgical repair.

December 17, 2017 Manchester United’s Antonio Valencia after sustaining an injury to his hamstring

Hamstring injuries are the most common muscular injury in athletes with most injuries occurring at the musculotendinous junction(1-3). There is some evidence that injuries that involve the intramuscular tendon require a longer rehabilitation period and have higher recurrence rates(2). Imaging is useful to determine the location and severity of injury, and with improved MRI resolution, the astute clinician can also determine whether a muscle injury involves the intramuscular tendon.

Traditionally all hamstring injuries – with the exception of large proximal tendon ruptures/avulsions – have been treated with conservative management. However surgical repair of injuries that involve the intramuscular tendon is now possible, and leading to some good results(3).

Hamstring tendon anatomy

The hamstring muscle group is comprised of three separate muscles: the biceps femoris (short and long head), semimembranosus and the semitendinosus (see figure 1). The proximal tendon of the semimembranosus originates from the lateral facet of the ischial tuberosity; the semitendinosus and the biceps femoris meanwhile share the common tendon origin on the medial facet of the ischial tuberosity(3).

Figure 1: Hamstring tendon anatomy


If both the proximal and distal portions of the bicep femoris are considered, the muscle tendon junction of the bicep femoris extends the full length of its muscle belly(2). The proximal tendon comprises approximately 60% of the length of the muscle(2). The free part of the proximal tendon (which has no inserting muscle fascicles) extends approximately 6.5 cm distally, with its long musculotendinous junction spanning 45% of the muscle length, to terminate deep within the muscle belly(2). The distal tendon and muscle-tendon junction extends up to 66% of the muscle length(2). Similarly, the semimembranosus has a proximal tendon and distal tendon that extends approximately 78% and 52% respectively into the muscle. The proximal tendon of the semitendinousus is the shortest of all the hamstring muscles, and extends about 30% of the length of the muscle.

The role of imaging

Clinically, some hamstring injuries resolve quickly whilst others take longer to recover (or may even fail conservative treatment and reoccur). One factor that has been thought to explain this is involvement of the intramuscular tendon(2). On MRI, the tendon may be seen to maintain its structural integrity, or it may lose its integrity and take on a irregular, wavy contour, or it may be frankly disrupted.

The British Athletics Muscle Injury Classification System (BAMICS) was developed to help clinicians determine not only the severity of a soft tissue injury, but also the type of tissue involved. This system is based on MRI findings and categorises the injury numerically by severity (1=small, 2=moderate, 3=extensive, 4=complete tear) and alphabetically by site (a=myofascial, b= myotendinous, c=intratendinous).

Researchers studying a series of hamstring injuries in AFL players showed that those with bicep femoris injuries without tendon disruption had a recovery time of 21 days, whereas those with tendon disruption treated non operatively recovered in 72 days. Those with tendon disruption requiring surgery recovered in 91 days(2).

In a study of track and field athletes, Pollock et al found similar results; when the injury extended into the tendon, athletes took longer to return to full activity (3c injuries took 84 days while 2b injuries took 21 days). They also has a higher rate of recurrence (2c injuries 63%; 3c injuries 57%; 2b injuries 6%)(2). Interestingly, there were no significant differences between injury grades 1 and 2 or classification a and b. This demonstrate that MRI is a useful tool with regard to hamstring injuries in the clinical setting as it identifies possible tendon involvement, which influences injury prognosis and management.

Case study of a cricketer

A 26-year old elite cricketer (wicket keeper) suffered a hamstring strain whilst playing a game of touch football during pre season training. The player had no history of hamstring or lumbar spine injury. The injury occurred when he was sprinting to catch an opposition player who had made a ‘break’, and while he was reaching forward to touch him.

The player felt sudden pain in his hamstring and fell to the ground. He was unable to walk so was assisted off the field. At the time, he described a feeling like a ‘balloon deflating’ in his hamstring. His pain was localised to the proximal one third of the hamstring, approximately 5-10cm from the origin.

A MRI scan was conducted the following day, showing a full thickness rupture of the biceps femoris tendon 78mm from its origin with 31mm retraction (see figure 2). Considering it was full thickness tear (grade 4 on BAMICS), a surgical opinion was advised. The player was reviewed with a surgeon three days post injury, and underwent surgery to repair the ruptured tendon the following day. There is no consensus on the best management of injuries that involve the intramuscular tendon(4). However, surgery was recommended as the return to play timeframes with conservative management and surgical management were similar, and the risk of recurrence was significantly lower with surgery.

Figure 2: MRI scan


Returning to play

Initially the aim was to return to playing elite domestic cricket at 12 weeks post surgery. Considering the specific injury and the demands of a game, return-to-play criteria were established, which outlined key physical parameters (clinical and functional measures) that needed to be met prior to returning to play (see table 1).


Table 1: Return-to-play criteria

 TestDescription of test and goalResult and date of previous bestDate achieved
Range of movement and clinical tests:Knee extension ROMSupine 90/90
70 deg L and R 20/6/18
72deg 22nd August
Hamstring bridge endurance testEndurance (>18reps 90% of screening score)20 reps 20/6/18
20 reps 20th August
Isometric hamstring in pronePain and strength >308N (90% previous score at 30deg)L 301N, R343N 9/7/18
431 N 10th Sept
Nordic test
More than 433 (90% of previous score)
L 472N, R 482N 8/6/18
L 501, R466. 17th Aug
Functional milestones:Resume normal walking - ADL's

Gait pattern
6th August
Start jogging
No pain walking10th August
High-speed running - *most critical*More than 25kph - GPS - minimum 5 sessions
5th session completed 18th Sept
Chronic GPS loads
Three consecutive weeks achieving all velocity band loads equivalent to Shield match17th Sept - high loads last 3 weeks (wks 5-7)
Batting - throw downsThrow downsCommenced 17th August
Batting - nets (unrestricted)

If no issues during previous week
Achieved 30th August
Stationary catching/keepingAbove knee high catches to start - progress as ableCommenced 17th August
Unrestricted keeping- (centre wicket)
Complete 5 full sessionsAchieved 18th August
2km TT7mins:30 or less7min 13/7/18
7:18 -17th Sept
Counter movt Vertical Jump
More than 61cm (90% of previous score)67cm (20/7/18)62cm -17th Sept
Run a quick single


Reach HSR with lunge for crease>26kphAchieved 11th Sept
Mid thigh pullMore than 4.64 relative force (90% of previous score)5.15 relative force 2/7/18
4.8- 19th Sept

The running criteria were based on GPS data obtained from the previous years data to ensure adequate capacity was achieved. Table 2 shows GPS data from a competition week for a one day tournament in the previous year for this player (including 2 games and training). Consistent high speed running is protective against hamstring injuries so it was deemed as a critical component to help mitigate the risk of re-injury when he returned to playing.


Table 2: GPD data

Total Distance Vel Band 1 (0-11.02km/hr) Vel Band 2 (11.02km-14km/hr) Vel Band 3 (14-20.99 km/hr) Vel Band 4 (20.99-25.99km/hr) Vel Band 5 (26+km/hr) Max Velocity
42 250m 33 489m4 515m3 391m671m 184m 30.7km/hr

The post operative instructions initially were as follows:

  • Focus on wound healing.
  • Weight bear as tolerated – avoid striding out on hills or on stairs beyond comfort.
  • Commence double leg bridging.
  • Commence bike and jogging when comfortable.

The initial phase of rehabilitation progressed very well (table 3 outlines the progression in the early phases of rehabilitation).


Table 3: Early phase of rehab

Week




SubjectiveClinical observations / testsSpecific hamstring exercisesTraining
1Able to walk without pain - still having difficulty putting pants on due to lack of hip function (feels wound, gets tight) otherwise ADLs going really well


Hip F ROM (supine)- 80deg
Hamstring length in supine 25 deg (at 80deg hip F)





Significant bruising.

Hip F ROM (supine)- 80deg
Hamstring length in supine 25 deg (at 80deg hip F)

Bridge- up on 2 legs hold on 1.

Standing and prone hamstring curls
ADLs only
2Going really well much better walking and putting pants on
able to bike and do boxing today
Hip F ROM (supine) -90deg hamstring length in supine at 90deg hip F- 25deg.

DL squat to 90deg no concerns.

HHD strength in prone (30deg) to P1 L 299, R 105
able to do hamstring curl in prone 2kg.
BW squat, hamstring curl prone 2kg.

Hip abd/add Theraband work in standing
Bike and boxing for fitness.

Commenced graduated return to run from day 14.
3Going well saw surgeon happy to progress as pain allowsNo restrictions with ADL's
HHD strength in prone0deg  L 235, R 132 ,30deg L 325, R 140,
90deg L 206, R 114
Progress running, commence batting and keeping drills

Hamstring exercises were commenced as pain allowed and were broken into a couple of phases. In the later stages, the emphasis was on eccentric loading to help protect against re-injury. Examples of hamstring exercises used in each phase were:

Initial phase (0-2 weeks)

  • BW squat
  • DL bridge on bed
  • Hamstring curl prone
  • Standing hamstring curl

Phase two (2-4 weeks)

  • Isometric holds in prone against resistance (various ranges)
  • Single leg bridge on box
  • Monster walks
  • RDL

Phase three (weeks 4-8)

  • DL hamstring slide outs progressed to SL
  • 45 deg DL hip ext progressed to SL
  • SL bridge with band resistance
  • GHR Straight leg SL hip ext

At four weeks post operation, the patient developedsome intermittent sharp stabbing pain in the gym when was doing a reverse lunge to step up. An ultrasound was arranged which showed some slight neural tethering around scar. The player was able to continue to training but modified his speed work when running. These symptoms then resolved with soft tissue treatment and neural mobilisation techniques by week six.

Hamstring strength

Hamstring strength was deemed to be an important criterion to determine the player’s readiness for return to play. To monitor strength progressions, hamstring strength testing was done through isometric testing (see table 4) and single leg bridge (based on the pre-season screening test). On pre-season testing for hamstring endurance two months prior to injury, the player was able to achieve 20reps for the single-leg bridge. At four weeks post operation, he was able to achieve the same result of 20 reps.


Table 4: Hamstring strength testing

TestPre-injuryWeek 2Week 3Week 4Week 5Week 6Week 7
HHD at 30deg proneBest (June 2018)

L) 418

R) 418
L) 343

R) 149
L) 330

R)202
L) 319

R) 283
L) 404

R) 431
L) 369

R) 356
L) 400

R) 413

Finally, from a specific hamstring strength and injury protection point of view, a Nordic hamstring test was performed seven weeks post surgery. The results were L) 501, R) 466N. This was slightly lower than his previous best a year beforehand (L) 472, R) 482) but showed good strength and symmetry.

As well as specific strengthening, running was an important component of his rehabilitation. Running was progressed as pain allowed, and by 5 weeks post op he was able to recommence HSR running (>26km/hr). By day 51, the player had completed his return-to-play criteria and returned to club cricket. He was able to bat for 25 overs. One week later, he was cleared to play a domestic 1-day game. Since then he has continued to play both 1-day cricket , 20/20 cricket and 4-day cricket without any recurrence of hamstring pain.

References:

  1. British Journal of Sports Medicine 51: 1021-1028
  2. British Journal of Sports Medicine 0: 1-5
  3. Orthopaedic Journal of Sports Medicine. 3 (10): 1-7
  4. British Journal of Sports Medicine. Vol0, No 0: 1-4

 

 

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