Hamstring strains--where do they occur?
Physiotherapists concerned with the treatment of hamstring strains require an understanding of the location of injury. Similarly knowledge of the anatomy of the injury site is necessary for the development of accurate models of injury mechanism. In order to describe the current state of evidence regarding specific sites of hamstring strain injury, a narrative review of the literature was undertaken. Although few firm conclusions can be drawn from the nine included studies it seems likely that the (long head of) biceps femoris is the most commonly strained hamstring muscle. Injury may be isolated to a single muscle but may also occur in muscles simultaneously, most typically the biceps femoris long head and semitendinosus. As generally held it appears that hamstring strain injuries involve a musculotendinous junction. However any further information regarding the specific sites of injury is difficult to interpret, the main reason being that the authors fail to consider the underlying morphology of the muscles. A detailed knowledge of precise sites of hamstring strain injury is essential to aid in the development of accurate clinical and biomechanical models, and fundamental to this is an appreciation of the anatomy of the muscles in question.
Woodley S, Mercer S (2004). Hamstring strains--where do they occur? New Zealand Journal of Physiotherapy 32(1): 22-28.
Key words: hamstring, strain, injury, magnetic resonance imaging
Injury to muscle may be caused either directly by contact (for example a contusion or laceration) or indirectly, when excessive strain or force culminates in a muscle strain injury (Garrett, 1990; Kujala et al., 1997; Worrell et al., 1994). Hamstring strain injuries are common in the sporting arena, and frequently occur in activities which involve running, sprinting, jumping or kicking (Best and Garrett, 1996; Clanton and Coupe, 1998; Garrett et al., 1989; Mair et al., 1996; Pomeranz and Heidt, 1993; Stanton and Purdam, 1989). As documented in several studies, incidence rates of hamstring strains range between 7.7% and 30% (Bennell et al., 1998; Heiser et al., 1984; Seward et al., 1993; Verrall et al., 2001), with relatively high recurrence rates of between 18% and 34% (Heiser et al., 1984; Orchard and Seward, 2002; Upton et al., 1996).
Given that such injuries are relatively common and frequently recur, no clear preventative or intervention strategies have emerged that are researched based (Devlin, 2000). Similarly strong evidence is lacking regarding the association between strain injury and the many proposed aetiological factors (Orchard, 2002), with the most established risk factors being increasing age and previous hamstring or posterior thigh injury (Bennell et al., 1998; Orchard, 2001; Verrall et al., 2001). In order to enhance both clinical diagnosis and treatment strategies, we need to establish and interpret patterns of hamstring injury. Likewise the location and structure of the injury site must be known if more complete models of injury mechanisms are to be developed. The need for this information is highlighted by the recognition of the complex architecture and innervation patterns of various human multiarticulated muscles (Bakkum et al., 1996; McKenzie, 2003; Segal et al., 2002; Wolf and Kim, 1997).
In vivo identification to establish the precise morphology of injured tissues has been facilitated by the advent of imaging techniques such as magnetic resonance (MR) imaging and ultrasonography. The purpose of this article was to review studies that have determined the anatomical location of clinically diagnosed hamstring strains in human subjects using soft tissue imaging techniques. This information was used to describe the current state of knowledge regarding the specific anatomical sites of hamstring strain injuries
Human studies published in the English language from 1960-2003 were located through searches of Medline, CINAHL, and EMBASE electronic databases. Reference lists of all reports were cross-referenced until no further studies were identified. Included were studies in which clinically diagnosed hamstring strains were verified using imaging techniques such as ultrasound, magnetic resonance imaging and computerised tomography. Studies were excluded from this narrative review if they reported on fewer than six hamstring strain injuries. Keywords used were hamstring, strain, injury and magnetic resonance imaging.
RESULTS AND DISCUSSION
Nine studies were found that described the site of injury in clinically diagnosed hamstring strains using either MR imaging, ultrasonography, computerised tomography, or radiography. Details of these studies are summarised in Table 1 and Table 2. More recent studies have used MR imaging and ultrasonography which have an advantage over computerised tomography as they do not require ionising radiation (Alanen et al., 1994; Lassere and Bird, 2001), and therefore optimise patient safety. Use of ultrasound is preferable to MR imaging with regard to cost, being relatively inexpensive, but it is suggested that MR imaging is the modality of choice for evaluating muscle-related injuries (Boutin et al., 2002; Sanchez-Marquez et al., 1999).
Which muscle is most commonly injured?
Review of the nine studies available identified biceps femoris as the most commonly strained hamstring muscle (De Smet and Best, 2000; Garrett et al., 1989; Koulouris and Connell, 2003; Lew et al., 1995; Pomeranz and Heidt, 1993; Slavotinek et al., 2002; Speer et al., 1993; Verrall et al., 2003) (Table 1). Collectively a total of 369 hamstring strain injuries verified by imaging techniques have been documented, with 254 (69%) of these injuries involving biceps femoris. Anatomically, biceps femoris comprises two separate components, a short head and a long head (Agur and Lee, 1999; Jenkins, 1998; Williams et al., 1995), but the majority of reviewed studies do not differentiate between the two. Yet, such information is necessary for the development of clinical and biomechanical models. Three investigations did precisely identify the long head as the specific component of the biceps femoris muscle that was most frequently injured (De Smet and Best, 2000; Garrett et al., 1989; Slavotinek et al., 2002), while one also described five minor injuries involving the short head (Slavotinek et al., 2002).
When attempting to determine the next likely hamstring muscle to be injured, the literature was not particularly informative. In three studies (De Smet and Best, 2000; Slavotinek et al., 2002; Verrall et al., 2003) the second most commonly injured muscle was observed to be semitendinosus, while in four other studies (Koulouris and Connell, 2003; Lew et al., 1995; Pomeranz and Heidt, 1993; Speer et al., 1993) it was the semimembranosus muscle. In total, 65 of the 369 (18%) documented hamstring strain injuries involved semitendinosus, whilst 48 (13%) involved semimembranosus. Two additional injuries reported by Garrett et al (1989) occurred at the common tendon of biceps femoris long head and semitendinosus.
In the articles reviewed, little discussion was found regarding possible reasons why the biceps femoris muscle appeared to be more commonly injured. However, in a paper discussing theories on the possible anatomy and mechanisms behind hamstring strains, Burkett (1976) suggested injury to biceps femoris may be secondary to the morphology of the muscle, labeling it a 'hybrid' muscle due to its long and short heads of origin. Although unsubstantiated Burkett (1976) proposed that this morphology, together with the different pattern of innervation of the two heads, may be a factor implicated in the cause of hamstring strain injuries. Similarly Oakes (1984) suggested that the biceps femoris muscle is more susceptible to strain injury due to attachment to both the ischial tuberosity and the length of the femur, making the muscle less extensible. The few reported injuries to the short head of biceps femoris may be in keeping with the proposed concept that muscles spanning two joints are more susceptible to injury than those acting on one joint (Clanton and Coupe, 1998; Garrett, 1990; Taylor et al., 1993; Yamamoto, 1993).
In four of the reviewed studies, a subset of subjects (in total 24/150, 16%) with clinically diagnosed hamstring strains demonstrated no signs of muscular injury when investigated with imaging techniques (Garrett et al., 1989; Lew et al., 1995; Slavotinek et al., 2002; Verrall et al., 2003). Association between neural structures and posterior thigh pain has been demonstrated in several other studies (George, 2000; Kornberg and Lew, 1989; Lew and Briggs, 1997; Turl and George, 1998), but a cause-effect relationship is yet to be established. However, it has been suggested that individuals with posterior thigh pain who have no signs of muscular injury on imaging may be experiencing pain referred to the area, from, for example, neuromeningeal structures (Verrall et al., 2001) or the lumbar spine (Verrall et al., 2003), with the referred pain mimicking the symptoms of a mild hamstring strain. Alternatively the muscles may be injured but evidence of this is below the current threshold of MR imaging sensitivity (Verrall et al., 2003). Interestingly, Verrall et al (2003) found that subjects with posterior thigh pain, but negative findings of hamstring strain on MR imaging, had significantly less pain and a better prognosis compared to those with positive findings on MR imaging indicative of muscle strain.
Are strains isolated to one muscle?
Four studies confirmed that isolated strain injuries do occur in individual hamstring muscles (De Smet and Best, 2000; Koulouris and Connell, 2003; Slavotinek et al., 2003; Verrall et al., 2003) (Table 1). These reports varied from 56.6% (17 of 30 athletes) (Slavotinek et al., 2003) through 60% (41 of 68 athletes) (Verrall et al., 2003), and 66.6% (10 of 15 athletes) (De Smet and Best, 2000), to 94% (145 of 154 athletes) (Koulouris and Connell, 2003) of cases. As Koulouris and Connell (2003) failed to relate injuries to individual hamstring muscles only the three remaining studies (De Smet and Best, 2000; Slavotinek et al., 2003; Verrall et al., 2003) provided sufficient information to determine which muscle was more likely to be strained when injured in isolation. Pooling the data from these three prospective case series, the biceps femoris muscle was involved most frequently, 76.5% (52 of 68 cases). Semitendinosus was strained in isolation much less commonly, 14% (10 of 68 cases) while semimembranosus appeared to be rarely injured, 8.8% (6 of 68 cases).
Four of the five remaining studies (Garrett et al., 1989; Lew et al., 1995; Pomeranz and Heidt, 1993; Speer et al., 1993) only reported the number of injuries observed in each muscle, and so did not provide adequate information regarding the occurrence of isolated injury. Interestingly the style of reporting in these papers implied that the injuries were observed as isolated strains but nowhere was this specifically stated.
Although strains may occur in one hamstring muscle in isolation, injury has also been observed to occur in two muscles simultaneously (De Smet and Best, 2000; Koulouris and Connell, 2003; Slavotinek et al., 2002; Verrall et al., 2003), most commonly involving the (long head of) biceps femoris and the semitendinosus muscles (De Smet and Best, 2000; Slavotinek et al., 2002; Verrall et al., 2003). In three studies, the proportion of injuries involving more than one muscle is similar, ranging from 33.3% (5 of 15 athletes) (De Smet and Best, 2000), to 39.7% (27 of 68 athletes) (Verrall et al., 2003) and 43.3% (13 of 30 athletes) (Slavotinek et al., 2002). Different to these findings are the results of Koulouris and Connell (2003) who observed concurrent injury in only 5.8% (9 of 154 athletes). Little discussion was found regarding possible reasons for sustaining injury to two muscles simultaneously, although it is suggested that more than one muscle may be affected because all hamstring muscles are subject to overstretching or forceful contractions. It is also proposed that different injury patterns may occur with different types of sporting activities (De Smet and Best, 2000), however no evidence was provided.
When more than one muscle was injured simultaneously, the muscles were generally labeled as either the primary or secondary site of injury, with two studies providing definitions of these terms. The primary site was determined by De Smet and Best (2000) to be the muscle with the greatest length and cross-sectional area of signal abnormality on MR imaging. If areas of increased signal intensity on MR imaging within a muscle were smaller than the primary injury, this was considered to be a secondary site. Similarly, Verrall et al (2003) stated that the primary site of injury was the muscle that exhibited the most extensive hyperintensity on MR imaging.
In five cases of simultaneous injury, De Smet and Best (2000) reported the long head of biceps femoris as the primary site of injury with semitendinosus being the secondary site of injury (Table 1). These findings differ from those of Slavotinek et al (2002), who found that in eleven cases of simultaneous injury involving biceps femoris long head and semitendinosus, biceps femoris was the primary site in six, and semitendinosus was the primary site in five (Table 1). Two further cases of simultaneous strain injury were observed by Slavotinek et al (2002), and the primary site of injury in one case was observed to be the biceps femoris long head muscle, and in the other, semitendinosus. The secondary site in both instances was the semimembranosus muscle. As previously mentioned, 5 of 30 cases of hamstring injury reported in this study involved the short head of biceps femoris.
Of the 27 strains reported by Verrall et al (2003) that involved two muscles concurrently, not enough information was given to ascertain definitive relationships. Of the primary injuries 17 were to biceps femoris and 10 involved semitendinosus. Semimembranosus was not reported as a primary site in any of the injuries, and was a secondary site in only 5 instances (Table 1).
In cases where the hamstring muscles are injured simultaneously it appears that the long head of biceps femoris and semitendinosus muscles are most commonly involved. The question of whether one or the other is more often the primary or secondary site of injury appears unclear.
Have specific sites of injury been described?
Of the reviewed studies, seven considered the specific sites and/or distribution of injury within the hamstring muscles (Table 2). It is generally held that muscle strains occur in the region of the musculotendinous junction (MTJ) (Garrett, 1996; Garrett and Best, 1994), and this was a finding in five of the studies (Brandser et al., 1995; De Smet and Best, 2000; Koulouris and Connell, 2003; Pomeranz and Heidt, 1993; Slavotinek et al., 2002). A collective total of 238 hamstring strain injuries were reported, with 155 (65%) observed to occur at, or involve, a MTJ. Given the paucity of published description of the macro- and micro-architecture of the hamstring muscles, the question is raised as to what constitutes a MTJ at a gross level. Some anatomical studies have revealed that the morphology of these muscles is complex, with each individual muscle (with the exception of the short head of biceps femoris proximally) being characterised by the presence of long proximal and distal tendons which extend into the muscle bellies (Garrett et al., 1989; McKenzie, 2003). Therefore each muscle does not comprise a belly with a tendon of attachment at each end, but instead distinct proximal and distal tendons give rise to elongated MTJs, which essentially run through the whole of the muscle, and are not confined to a small area.
When considering specific sites of injury within the musculotendinous complex of each individual hamstring muscle little consistency existed with use of terminology between studies, making interpretation and comparison difficult. Garrett et al (1989) only indicated that most injuries occurred proximally within the muscle belly or common tendon. Brandser et al (1995) were a little more specific indicating that most injuries (20/22) involved the proximal attachments of the hamstring muscles at the conjoined tendon or ischial apophysis. Confusingly they then stated (when referring to 13 of these injuries investigated using MR imaging) that evidence of injury to the MTJ was observed in 5 cases, and to the muscle in 1 case (Table 2). No further details regarding specific location of strain injury were supplied.
With regard to the site of injury, some authors arbitrarily divided the muscles into proximal (upper), middle, and distal (lower) thirds (Koulouris and Connell, 2003; Pomeranz and Heidt, 1993; Verrall et al., 2003). Combining the information from these three studies there were 249 reported injuries, with 86 (34.5%) observed to occur in the proximal third, 109 (43.8%) in the middle third, and 53 (21.3%) in the lower third of the muscle. Of these, Pomeranz and Heidt (1993) were the only authors who specifically denoted whether or not injury involved the MTJ. Injuries to biceps femoris were observed at the proximal MTJ, in the superficial belly of the middle section, and at the MTJ and tendon within the distal section. Only the MTJ and tendon of the distal semitendinosus muscle was involved, while in the semimembranosus muscle the tendon proximally, the belly of the middle section, and the MTJ and tendon of the distal section were described as sites of injury (Table 2). Although these results provide some indication of the general location of injury, the lack of precision in relating the injury site to the precise anatomy of each muscle means that these results provide little useful information for modeling of the mechanism of injury.
The remaining two studies used different methods than those above to categorise strain injuries. De Smet and Best (2000) divided the hamstring muscles into sections comprising insertions (proximal and distal), tendons (proximal and distal) and MTJs (proximal, intramuscular and distal). The femoral origin of the biceps femoris short head muscle was used as a landmark, and injuries were defined as proximal if they occurred above this point, and distal if they were below this point. Slavotinek et al (2002) used similar criteria to that of De Smet and Best (2000), with potential sites of injury including the MTJ (proximal or distal) or the muscle belly (adjacent to, or separated from the intramuscular tendon). Again an injury was considered to be proximal if it occurred above the level of the origin of the short head of biceps muscle. Although more precise, neither of these two studies made reference to the anatomical basis used to define such structures as tendons, MTJs or intramuscular MTJs, which were used to classify sites of injury. Therefore their divisions may be arbitrary rather than based on morphological evidence.
Slavotinek et al (2002) observed that of the 30 cases of hamstring injury 28 (93.3%) involved a MTJ, and of these, 24 (85.7%) cases involved the intramuscular tendon and 4 (14.3%) a MTJ. For those injuries occurring at the intramuscular tendon 5 (20.8%) extended into the proximal MTJ. Of the reported injuries 11 (36.7%) were observed to occur proximally, however the muscles afflicted were not detailed. Slavotinek et al (2002) consistently refer to 30 cases of hamstring injury, however this is misleading because more than one muscle was injured in some instances, giving a total of 48 individual injuries (see Table 1). Therefore, for example, if biceps femoris and semitendinosus were simultaneously injured, this would be considered one case. If this was one of the 28 cases involving a MTJ, from the information provided we cannot deduce if both or only one of the muscles sustained an injury at the intramuscular tendon or MTJ.
Of the nine reviewed studies, the results reported by De Smet and Best (2000) were the most morphologically accurate and meaningful, as they were the only authors to report precise injury sites for each individual muscle (Table 2). For example, of the 11 injuries inflicted to biceps femoris, 4 involved the proximal MTJ, 3 the proximal intramuscular MTJ, and 4 the distal intramuscular MTJ. When generally considering the hamstring muscles 8 of the 20 injuries were partial tears occurring at an intramuscular MTJ, while 7 involved a MTJ. Nine were observed to occur proximally, six were distal, and the location of the remaining five was not reported.
Given that hamstring strain injuries are a common problem, it is surprising to find relatively few studies that investigate the exact location(s) of these injuries. It is therefore difficult to establish a pattern of site of injury from this clinical literature as studies are few, study designs and definitions differ, and precise details of the location of injury within each muscle are commonly not provided. Moreover the authors generally do not consider the gross morphology of the muscles under investigation, and therefore fail to provide evidence regarding the basis used to define anatomical structures implicated as sites of injury.
From the reviewed studies only a few definitive answers can be made in response to the question 'where do hamstring strains occur?' The results of these studies indicate that the biceps femoris muscle, more particularly the long head of biceps femoris, is most commonly injured. Hamstring strain injury may occur in isolation, however when muscles are injured simultaneously the (long head of) biceps femoris and semitendinosus appear to be typically implicated. Many injuries are reported to occur near or at a MTJ, but no patterns emerge regarding exactly where injuries occur within the musculotendinous complexes of each individual muscle. Knowledge of the location of injury is important to physiotherapists involved in the assessment and treatment of hamstring strains. Similarly, the development of clinically relevant models of mechanisms of injury relies on accurate descriptions of the location and morphology of the injury site. Further research is required to establish definite patterns of hamstring strain injury, however accuracy and consistency will only be achieved if the morphology of each of the individual hamstring muscles is considered.
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ADDRESS FOR CORRESPONDENCE:
Stephanie Woodley, Musculoskeletal Research Group, Department of Anatomy & Structural Biology, Otago School of Medical Sciences, University of Otago, PO Box 913, Dunedin. Email: firstname.lastname@example.org. Phone: 03 479 5145. Fax: 03 479 7254
Stephanie J Woodley
PhD candidate, Department of Anatomy & Structural Biology, University of Otago
Susan R Mercer
BPhty (Hons), PhD, FNZCP
Senior Lecturer, Department of Anatomy & Structural Biology, University of Otago
Table 1. Results of review regarding the location of hamstring strains as verified by imaging techniques Study design Inclusion Author, Country of Sample /exclusion Date origin characteristics criteria Garrett et Prospective 10 subjects, Inclusion: recent al, 1989 case series. college athletes hamstring injury America or other patients presenting with injury Pomeranz Prospective 14 male Inclusion: clinical and case series. professional diagnosis of Heidt, America athletes (aged hamstring injury 1993 20-29) over a 2 year period Speer et al, Retrospective 50 nonconsecutive Inclusion: acute 1993 case series. patients over 9 lower extremity America years muscle strain Lew et al, Prospective 30 Victorian Inclusion: 1995 case series. football league/ clinically Australia Australian diagnosed football league hamstring strain players (diagnosed by club doctor) Brandster et Retrospective 22 patients Inclusion: hamstring al, 1995 case series. (18 male, injuries (classified America 4 female) as acute < 1 week, subacute between 1 week & 3 months, chronic > 3 months). De Smet Prospective 15 university Inclusion: hamstring and Best, case-series. athletes injury 2000 America (14 male, 1 female), recruited over a 20-month period Slavotinek Prospective 37 Australian Inclusion: et al, 2002 case series. rules football clinically Australia players recruited suspected over a 9-month hamstring injury period (defined as posterior thigh pain that prevented training or playing). Exclusion: previous hamstring injury Koulouris Retrospective 170 patients (154 Inclusion: patients and case series. male, 16 female, referred with a Connell, Australia mean age 28.2 clinical diagnosis 2003 years) over 37 is of hamstring months. muscle complex 120 football injury players, 32 athletes, 17 cricketers, 10 water-skiers Verrall et Prospective 83 Australian Inclusion: posterior al, 2003 case series. rules football thigh injury that Australia players (all caused the athlete male) over 2 full to miss training or playing seasons playing Exclusion: injuries involving direct trauma to the thigh Author, Date Imaging Muscle(s) injured Garrett et CT scan within 48 No acute lesion 2 al, 1989 hours of injury Hamstring injury 8 (9/10) 5 BFlh 1 SM 2 Common tendon Pomeranz MRI within 8 Quadratus femoris injury 2 and days of injury Hamstring injury 12 Heidt, 6 BF 1993 5 SM 1 ST Speer et al, Imaging 2 to 4 Hamstring strain injury 17 1993 days post-injury 11 BF CT scan 4 SM 23 MRI 2 ST Lew et al, US within 3 days of No lesion detected 5 1995 injury. If negative, Hamstring injury 15 MRI 4 days later 11 BF 4 SM Brandster et Time frame to NA al, 1995 imaging not indicated 11 radiographs 14 MRI 1 CT 2 Conventional tomography De Smet MRI within 5 Hamstring injury 20 and Best, days of injury 11 BFlh: 6 isolated 2000 5 primary site 8 ST: 3 isolated 5 secondary site 1 SM: 1 isolated Slavotinek MRI within 2 to 6 No lesion 5/37 et al, 2002 days of injury Adductor magnus injury 1/37 Vastus lateralis injury 1/37 Hamstring injury 48 26 BFlh: 14 isolated 7 primary site 5 secondary site 15 ST: 3 isolated 6 primary site 6 secondary site 2 SM: 2 secondary site 5 BFsh: minor injury, next to BFlh muscle belly Koulouris Imaging within Hamstring muscle injury 154 and 1 to 10 days of 124 BF Connell, injury 21 SM 2003 97 MRI 9 ST 102 US 9 cases of simultaneous 20 both MRI and injury US 5 BF & SM 1 BF & ST 3 two injury sites within BF Verrall et MRI within 2 to 6 No detectable hamstring al, 2003 days of injury muscle strain on MRI 12 Gluteus maximus injury 1 Adductor magnus injury 1 Vastus lateralis injury 1 Hamstring strain 68 (athletes) 55 BF: 32 isolated 17 primary 6 secondary 30 ST: 4 isolated 10 primary 16 secondary 10 SM: 5 isolated 5 secondary Key: BF: biceps femoris BFlh: biceps femoris long head BFsh: biceps femoris short head NA: no information is available regarding this aspect SM: semimembranosus ST: semitendinosus MTJ: musculotendinous junction US: ultrasound CT: computed tomography MRI: magnetic resonance imaging Table 2. Specific sites and distribution of hamstring strain injury as determined using imaging techniques Author, Date Specific sites of injuries Garrett et al, 8 hamstring injuries--most injuries were proximal 1989 within the muscle belly or common tendon Pomeranz and 12 hamstring injuries Heidt, 1993 4 superficial muscle belly injury 4 MTJ (2 proximal, 2 distal) 1 tendon (proximal SM) Brandser et al, 22 hamstring injuries 1995 20 proximal attachments of hamstring muscles (either at conjoined tendon or ischial apophysis) 1 distal insertion BF and avulsion head of fibula 1 musculotendinous injury BF Of those who had MRI (13) 8 acute injuries involving conjoined tendon (2 avulsion injuries, 5 partial tears and evidence of injury to MTJ, 1 avulsion injury of fibular head involving BF) 5 partial tearing and evidence of injury to MTJ 2 subacute injuries (1 diffuse injury throughout the muscle, 1 avulsion and retraction of conjoined tendon) 1 diffuse injury throughout the muscle 3 chronic injuries De Smet and 20 hamstring injuries, all were partial tears, Best, 2000 all occurred at a MTJ 8 intramuscular MTJ (4 proximal, 4 distal) 7 MTJ (5 proximal, 2 distal) 5 location of injury not detailed Slavotinek et al, 30 hamstring injuries, 11 injuries were situated 2002 above the origin of BFsh 28 injuries involved a MTJ 24 intramuscular tendon (5 extended into MTJ, all proximal) 4 MTJ (3 distal, 1 proximal) 2 small isolated injuries to BFlh that extended to the epimysium Koulouris and 154 hamstring injuries, 98 involved a MTJ Connell, 2003 A haematoma was associated with 136 of the muscle injuries 124 BF injuries 76 MTJ 43 epimyseal injuries 5 intramuscular haematomas 21 SM injuries 17 MTJ 4 NA 9 ST injuries 5 MTJ 3 epimyseal tears 1 NA Verrall et al, 83 posterior thigh injuries, 68 were MRI-positive 2003 hamstring muscle strains Author, Date Distribution of injuries Garrett et al, NA 1989 Pomeranz and 12 hamstring injuries Heidt, 1993 6 BF 1 proximal MTJ 4 middle 1 distal MTJ 5 SM 1 proximal tendon 1 proximal MTJ 3 middle 1 ST 1 distal MTJ Brandser et al, NA 1995 De Smet and 11 BF isolated 2 proximal intramuscular MTJ Best, 2000 4 distal intramuscular MTJ primary 4 proximal MTJ 1 proximal intramuscular MTJ 8 ST isolated 1 proximal intramuscular MTJ 2 distal MTJ secondary 5 NA 1 SM isolated 1 proximal MTJ Slavotinek et al, NA 2002 Koulouris and 124 BF 54 proximal Connell, 2003 48 middle 22 distal 21 SM 16 middle 5 distal 9 ST 8 middle 1 NA Verrall et al, Sites of maximal tenderness as determined by 2003 the athletes 29 upper third 22 MRI positive 5 MRI negative 2 alternative MRI explanation for injury 30 middle third 24 MRI negative 5 MRI negative 1 alternative MRI explanation for injury 24 lower third 22 MRI positive 2 MRI negative Key: BF: biceps femoris BFlh: biceps femoris long head BFsh: biceps femoris short head ST: semitendinosus SM: semimembranosus MRI: magnetic resonance imaging MTJ: musculotendinous junction NA: no information is available regarding this aspect
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|Author:||Woodley, Stephanie J.; Mercer, Susan R.|
|Publication:||New Zealand Journal of Physiotherapy|
|Date:||Mar 1, 2004|
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