Scand J Med Sci Sports 2000: 10: 304–307 COPYRIGHT C MUNKSGAARD 2000 ¡ ISSN 0905-7188

Printed in Denmark ¡ All rights reserved

Case Report

Sports related hamstring strains – two cases with different etiologies andinjury sites

C. Askling1, M. Tengvar2, T. Saartok3, A. Thorstensson1

1Department of Sport and Health Sciences, University of Physical Education and Sports and Department of Neuroscience,Karolinska Institutet, Stockholm, 2Department of Radiology, Sophiahemmet, Stockholm, 3Section of Orthopaedics, Department ofSurgery, Visby Hospital, Visby, SwedenCorresponding author: Carl Askling, Department of Sport and Health Sciences, University College of Physical Education andSports, Box 5626, 114 86 Stockholm, Sweden

Accepted for publication 15 March 2000

Hamstring strains are common injuries in sports. Knowl-edge about their etiology and localization is, however,limited. The two cases described here both had acute ham-string strains, but the etiologies were entirely different.The sprinter was injured when running at maximal speed,whereas the hamstring strain in the dancer occurred dur-ing slow stretching. Also the anatomical localizations of

Hamstring strains are common in sports with highdemands on speed and power, for example sprint run-ning and soccer (Garett, Califf, Bassett, 1984). Thereis anecdotal evidence that hamstring strains also arerather frequent in other sports, such as dancing. Thediagnosis and treatment of these injuries have beenbased mainly on empirical evidence or simply trialand error. Hamstring strains are complex injuriesthat probably involve a multi-factorial etiology. Poss-ible relationships between strength, flexibility, warm-up, fatigue, etc., and hamstring strains have been sug-gested (Worrell, 1994). Scientifically based evidencefor associations between such predisposing factorsand hamstring injuries is, however, lacking. Also, it isstill unclear in which of the four individual hamstringmuscles the strains most frequently occur. Clinically,the biceps femoris is reported to be the most com-monly injured muscle within the hamstring musclegroup (Garrett, Rich, Nikolaou, Volger, 1989). Basedon experimental data, it is generally claimed thatstrain injuries most often occur near the muscle–ten-don junction, particularly in two-joint muscles (Gar-rett, 1996; Järvinen, 1994). Whether the injury in-volves primarily muscular or tendinous tissue is stillan open question. Magnetic resonance imaging(MRI) offers a possibility to determine the exact ana-tomical localization and extent of such soft tissue in-juries (Brandser, El-Khoury, Kathol, Callaghan, Te-arse, 1995). The two cases presented here will illus-

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the injuries clearly differed. Magnetic resonance imaging(MRI) revealed pathological changes in the distal semiten-dinosus muscle in the sprinter and the proximal tendon ofthe semimembranosus muscle in the dancer. Subjectively,both athletes severely underestimated the recovery time.These case observations suggest a possible link betweenetiology and localization of hamstring strains.

trate that the anatomical localization and tissueinvolvement of acute hamstring strains, as deter-mined with MRI, is variable and possibly related tothe mechanism of injury.

Case 1

A 20-year-old male world-class sprinter (personalbest 9.92 s) suddenly felt a sharp pain in his rightposterior thigh after approximatley 60 m of a 100 mrace. He finished the race, but was unable to continueat maximal speed. His time was 10.30 s, finishingthird in the race. A few minutes after the race, anexternal elastic compression bandage was applied onthe injured thigh. The athlete was instructed not toprovoke pain from the thigh. Analgesic medicationwas not needed. The sprinter had no history of priorinjury to the thigh or any predisposing signs of injury(such as pain or stiffness) in his back thigh before thecompetition.

Fifteen hours after the acute trauma, a carefulphysical examination was undertaken. The athletehimself estimated the injury to be minor, being con-vinced that he could run another 100 m race the nextday. He experienced stiffness and pain in the injuredarea and had a slight limp while walking at normalspeed on even ground. During examination of theathlete in a prone position with straight legs, pal-pation did not reveal any defect but a tender area was

Hamstring strains

Fig. 1. MR-images of case 1. Sagittal fat saturated proton-density image (a) dem-onstrating the partial tear in the semitendinosus muscle with extrafascial fluid col-lection (black arrows) and subcutaneous edema (white arrows). Transverse fat satu-rated proton-density images of both legs (b) with the partial tear in the right semi-tendinosus muscle and extrafascial fluid collection compared to the left side(arrows).

present in the medial hamstring muscle group. Thepainful area was localized over one of the medial bel-lies of the hamstring complex (m. semitendinosus(ST) or m. semimembranosus (SM)) and the centerof the most painful area was situated approximately15 cm proximal to the medial articular cleft of theknee. The athlete experienced moderate pain whenvoluntarily flexing and extending the knee in theprone position, the pain being more pronounced dur-ing extension. Using the straight leg raise (SLR) testin the supine position, the injuried leg could bemoved passively to a hip angle of 60æ from the hori-zontal before reaching the limit of pain tolerance.Furthermore, the pain became more pronouncedwhen an isometric contraction was tried in that posi-tion.

MRI was performed 20 h after the acute trauma,using a 1.5 Tesla superconductive magnet (Signa;General Electric Medical Systems, Milwaukee, USA).MRI consisted of transverse and sagittal proton-den-sity fast spin-echo with frequency selective fat satu-ration and coronal fast short time inversion recovery(STIR). The MRI showed a partial tear in the semit-endinosus muscle at the distal muscle–tendon junc-tion with the center approximately 15 cm proximal tothe medial articular cleft of the knee (Fig. 1a and b).Approximately 1/4 of the cross-sectional area and 7.5cm of the length of the muscle in the cranio-caudaldirection had an abnormal signal. The greatest depthand width of the abnormal signal was 4¿2 cm. The

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intramuscular lesion was predominantly located inthe lateral/anterior part of the muscle belly. An extra-fascial fluid collection was located around the wholecircumference of the muscle, but predominantlyanteriorly and laterally, and covered 15 cm in thecranio-caudal direction. At the distal 5 cm of theextrafascial fluid collection there was also a subcuta-neous edema. There was no total disruption or anyretraction of the muscle. The tendon distal to the in-jury site was unaffected.

After a discussion between the athlete, his coachand the sports medicine staff, it was agreed that anextended rehabilitation period for this injury wasneeded. The goal was set to enable the athlete to com-pete 3 weeks later. However, the healing processturned out to be even slower, forcing the athlete togive up his racing during the rest of the outdoor sea-son, approximately 6 weeks before planned. Thesprinter was put on a rehabilitation program that in-cluded muscle strength and flexibility training. Cri-teria for advancement to the next stage of rehabili-tation were full painless range of motion and goodflexibility. After 18 weeks the athlete was able to per-form on the same level as before the injury.

Case 2

A 22-year-old female professional dancer felt a sud-den sharp pain in her right posterior thigh whenslowly stretching her right hamstrings at home after

Askling et al.

Fig. 2. MR-images of case 2. Sagittal STIR image (a) showing the partial tearin the thickened semimembranosus tendon and surrounding fluid (arrows).Transverse T1-weighted images of both legs (b) with the right semimem-branosus tendon considerably thickened compared to the other side (arrows).

a day of dancing in school. She did not know how tohandle the situation. After consulting a medicalbook, she applied the ‘‘RICE’’ principle (rest, ice,compression and elevation) to the leg. The dancerhad no history of any previous injury or any of thepredisposing signs of injury in the thigh beforestretching. However, she had felt some stiffness afterspecific hamstring exercises during the weeks immedi-ately preceding the injury.

Seventeen hours after the acute trauma, a carefulphysical examination was performed. The dancerherself thought that the injury was small, being con-vinced that she could return to dancing practice in afew days. She experienced stiffness and pain in theinjured area while walking at normal speed on evenground. With the dancer in a prone position withstraight legs, palpation dit not reveal any defect buta tender area localized over one of the medial belliesof the hamstring muscle group (ST or SM). The cent-er of the most painful area was approximately 10 cmdistal to the tuber ischii. When voluntarily flexingand extending the knee in a prone position the dancerexperienced burning pain. This pain was present inthe whole range of motion being more pronouncedduring extension, especially during the last 30æ of ex-tension. Using the SLR test in a supine position, theleg could be lifted passively to a hip angle of 90æ fromthe horizontal before reaching the limit of pain toler-ance. The pain increased when an isometric contrac-tion was attempted in that position.

MRI was performed with a 1.0 Tesla superconduc-

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tive magnet (Magnetom Impact Expert, Siemens, Er-langen, Germany) 72 h after the trauma using aphased array coil. MRI consisted of transverse, sagit-tal and coronal STIR images, transverse spin-echoT1-weighted images and transverse fast spin-echo T2-weighted images. The MRI revealed an apparent par-tial tear in the proximal semimembranosus tendon(Fig. 2a and b). The tendon was thickened to ap-proximately double the thickness of the contralateraltendon with intratendinous edema from the origin atthe tuber ischii and 8 cm in the caudal direction.Also, there was a small fluid collection surroundingthe tendon. However, continuity of the tendon wasunaffected and the SM muscle belly did not show anyabnormalities. In the proximal and dorsal aspects ofthe adductor magnus muscle belly, close to the semi-membranosus muscle, there was a 1¿2 cm area ofedema corresponding to a small partial tear.

The dancer was put on a standard rehabilitationprogram and she was able to rejoin her dance practice12 weeks after the injury. After one year, she had notregained full performance ability in dancing, e.g. shewas still unable to perform the sagittal split position.Even at that time she felt stiffness in her rear thighand experienced fatigue earlier in the injured leg com-pared with the uninjured when practising.

Discussion

The two current cases, representing different sports,clearly demonstrate that hamstring strains can have

Hamstring strains

different anatomical localizations and involve differ-ent parts of the musculotendinous complex. Further-more, the fact that the injuries occurred under en-tirely different circumstances, one fast active move-ment, the other slow and passive, raises the questionof a possible link between etiology and character ofthe injury.

Most researchers state, based on studies of powerevents such as sprinting, that the long head of bicepsfemoris is the muscle within the hamstring group thatis most prone to injury in sports (Garrett et al., 1989;Garrett, 1996; Burkett, 1976). Furthermore, the ana-tomical localization of more extensive hamstringstrains is claimed to be close to the origin on tuber ossisischii (Garrett, 1996; Orava & Kujala, 1995). The pres-ent cases show a different pattern with one distal injuryin the ST muscle (sprinter) and one proximal injuryprimarily in the tendon of the SM muscle (dancer).The sprinter was injured during maximal speed run-ning, presumably putting extreme demands on ham-string muscle function, whereas the dancer was injuredduring a well controlled, slow stretching. The injury ofthe dancer suggests that a ‘‘muscle strain’’ in fact canbe a partial tendon rupture.

MRI is a relatively new method to localize and esti-mate size of strain injuries in muscles. As demon-strated here, the localization and extent of the injurycan be evaluated in detail. It has also been suggestedthat the duration of the rehabilitation period may bepredicted based on the severity of the injury as judged

References

Burkett LN. Investigation into hamstring Garrett WE, Rich FR, Nikolaou PK, Pomeranz S J, Heidt Jr. RS. MR Imagingstrains: The case of the hybrid muscle. Vogler JB III. Computed tomography in the prognostication of hamstringJ Sports Med 1976: 3: 228–231. of hamstring muscle strains. Med Sci injury. Radiology 1993: 189: 897–900.

Brandser EA, El-Khoury GY, Kathol Sports Exerc 1989: 21: 506–514. Thorsson O. Diagnosis and treatment ofMH, Callaghan JJ, Tearse DS. Järvinen M. Muscle injuries in sports. In: muscle injuries in athletes –Hamstring injuries: radiographic, Viitasalo M, Kujala U, eds. The way to experimental and clinical studies.conventional tomographic, CT and MR win. Helsinki: The Finnish Society for Thesis. Lund: Medical Faculty, Lundimaging characteristics. Radiology Research in Sport and Physical University, 1996.1995: 197: 257–262. Education, 1994: 69–76. Worrell TW. Factors associated with

Garrett WE. Muscle strain injuries. Am Orava S, Kujala UM. Rupture of the hamstring injuries: an approach toJ Sports Med 1996: 24: S2–S8. ischial origin of the hamstring muscles. treatment and preventive measures.

Garrett WE, Califf JC, Bassett FH III. Am J Sports 1995: 23: 702–705. Sports Med 1994: 17: 338–345.Histochemical correlates of hamstringinjuries. Am J Sports Med 1984: 2: 98–103.

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by MRI (Pomeranz & Heidt, 1993). However, due toits cost, MRI should be carefully evaluated in orderto arrive at principles for its use, and additionallyestimate the cost–benefit of the method.

For high-level athletes, a quick return to trainingand competition is imperative (Thorsson, 1996). Oneimportant task for the sports medicine staff is to in-form the athlete and his/her coach about the prog-nosis of time and type of rehabilitation needed to re-turn to their specific sport.

None of the present athletes had experienced a pre-vious injury in the hamstring muscle group.

This may explain why both athletes greatly under-estimated the time it would take to return to compe-tition and practice.

Perspectives

The present results point out the importance of find-ing the exact anatomical localization and injuredtissue in a hamstring strain. It also emphasizes theimportance of systematically mapping the injury siteversus the injury mechanism in various sports. Thistype of information, including size of injury, corre-lated to the time to get back to sport, is required toevaluate different rehabilitation programs.

Key words: hamstring strain; sprinter; dancer; MRI;rehabilitation.