Regarding the general player history:
Has the player suffered similar injuries before?
(Some muscle injuries have a high reinjury rate, players may report a previous injury, often near the current place of injury [3])
Is he/she susceptible to injuries?
Is the player using any medications?
Regarding the mechanism of injury:
What was the trauma mechanism?
(A direct blow to the muscle or an indirect mechanism)
During work, training or competition?
When did it start?
Date and relationship with the sports session (beginning, middle or the end of the session)
How did it start (Suddenly, gradually, progressively)
Any audible pop or snapping sensation with the onset of pain [4]
Regarding the initial progress:
Was the player able to continue or was he forced to stop?
How was the player treated following the immediate injury?
How has the pain progressed over time?
Physical examination involves the inspection and palpation of the injured area, as well as testing the function of the injured muscles both with and without external resistance. A bilateral comparison should always be performed. The physical examination is performed to determine the location (muscle, tendon or fascia) and the injury severity.
For injuries involving the intramuscular tendon, a ‘battery’ of tests which incorporate measures of function, strength and range of motion may provide an acceptable estimate of rehabilitation duration [5]. Specifically, a past history of hamstring strain and being unable to walk at a normal pain-free pace [6].
For injuries to the proximal free tendon, the amount of impairment identified from these tests is not predictive of the recovery time needed to return to pre-injury level [7]. We recommend that specific measures be used during the examination of all acute muscle injuries, at the very least to serve as a baseline from which progress can be assessed.
Muscle examination should include:
Inspection | Looking for ecchymosis or deformities on the muscle belly profile |
Palpation | Useful for identifying the specific region/muscle injured through pain provocation, as well as the presence or absence of a palpable defect in the musculotendinous junction |
Strength assessment | Through manual resistance applied distally to the injury site. Due to the changes in musculotendon length that occur with joint positions, multiple test positions are used to assess isometric strength and pain provocation. It is important to note that pain provocation with this assessment is as relevant as noting weakness |
Range of motion | Tests should consider joints at either end of the injury site. For hamstring injuries, passive straight leg raise (hip) and active and passive knee extension test (knee) (AKET, PKET) are commonly used to estimate hamstring flexibility and maximum length [8]. Pain and discomfort during testing are key considerations when performing and evaluating these tests |
Muscle length | The extent of joint motion available should be based on the onset of discomfort or stiffness reported by the player. In the acutely injured athlete, tests are often limited by pain and may not provide a valid assessment of musculotendon extensibility |
Pain provocation manoeuvres | It has been suggested that players with a biceps injury would feel more pain during stretching than contraction (on VAS), while those injured in SM or ST will have more pain during contraction than stretching |
34.1 Imaging of Muscle Injury
Unless an avulsion fracture with bony fragment or apophyseal fracture in a skeletally immature individual is suspected, the value of plain radiographs is limited [9]. On the other hand, MRI and US are able to describe the location (which muscle and tissue), the injury size and the lesion nature (oedema, haemorrhage) as depicted by echotexture and signal intensity, respectively [10].
Both imaging modalities are useful in identifying muscle injuries when oedema and haemorrhage are present [11]. As a result of its cost-effectiveness, US has been traditionally the imaging system of choice for clinical diagnosis of muscle injuries. However, it has the disadvantage of being radiologist’s experience dependent.
US is a dynamic and interactive examination, allowing ‘echopalpation’ of painful areas which complements the clinical examination. US also enables the monitoring of progress and can guide the evacuation of fluid collections, as such it is of great help in topographic diagnosis. However, MRI is considered superior for evaluating injuries to deep portions of muscles [12], or, when a previous injury is present as residual scarring, it could be misinterpreted in an US image as an acute injury.
Due to its increased sensitivity in highlighting subtle oedema, measuring the size of injury (length and cross-sectional area) is probably more accurate with MRI.
MRI is believed by some doctors to be useful in prognosticating return to play (RTP) with MRI grading associated with lay-off times after injury [13].
On the other hand, some studies concluded that there is currently no strong evidence for any MRI variable to predict the time to RTP after an acute hamstring injury due to considerable risks of bias in the studies [14].
Hamstring muscle injuries are the very well documented in the literature, and MRI provides very specific anatomical and pathological information. MRI can sensitively evaluate the relative involvement of tendons, fascia and muscle contractile tissue [15]. MRI has demonstrated to be more accurate than US in the evaluation of proximal hamstring injuries, and it can assess the degree of tendon retraction, which has proved to be an important element of preoperative planning in proximal hamstring ruptures or avulsions [16]. Whereas MRI correctly identified all avulsion cases, US identified only 58% of hamstring avulsions despite the examination being performed by experienced musculoskeletal operators [17].
In distal hamstring injuries, US could better detect injuries as a result of the more superficial anatomy of the distal hamstring tendons [10]. With injuries near the groin area or close to the myotendinous junction, MRI has also demonstrated its superiority over US [11].
The limited availability and high costs of MRI may restrict the use of this modality for routine assessment of injuries among junior and amateur athletes. Schneider-Kolsky et al. showed that MRI was not required for estimating the duration of rehabilitation for an acute minor hamstring injury in professional football players. However, a positive MRI result appeared useful as a predictor of duration of rehabilitation in severe hamstring injuries and also that MRI was helpful in the planning of surgical interventions [5].
34.1.1 Routine MRI Protocol
As an absolute minimum, each MRI examination should generally include at least two orthogonal planes and pulse sequences. In addition to the requisite axial plane, the long-axis plane is generally sagittal (when evaluating abnormalities at the anterior or posterior aspect of an extremity) or coronal (when evaluating abnormalities at the medial or lateral aspect of an extremity). At least one of these pulse sequences should use a fat-suppression technique [18].
34.2 Initial Management of a Suspected Muscle Injury
In Table 34.1, the most appropriate timing for carrying out complementary investigations is highlighted. Real utilization will depend on the physician and athlete preference, funding and the availability of resources.
Table 34.1
Summary of methodology diagnosing muscle injuries and timing
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