Introduction

Muscle injuries are a prevalent sport problem, in which contusions represent 12.1% of all injuries. Muscle contusions are more common in men (15.1%) than in women (6.3%). Contusion injuries are more probable (per athlete exposure) to happen during competition than practice. Whereas the sites of contusions are not reported by body region in epidemiologic investigations, contusions have been said to account for 14.2% of all thigh injuries seen in high school sports (15.8% in men and 11.2% in women) and 19% of all muscle injuries occurring in professional football.¹

Thigh contusion occurs due to an improperly dissipated compressive force on the quadriceps muscle that compresses the muscle and surrounding tissue against the femur. This interrupts the myofibers and capillaries. Since the thigh does have considerable potential space, a big hematoma may form; therefore, treatment should be started early. 

When there is a contusion of the thigh, the muscle heals by a repair mechanism rather than through regenerative mechanisms, which occur in bone. The tissue never returns to the original state, and scarring will occur. Healing occurs in 3 overlapping stages- destruction stage (0–7 days), 2 repair stage (7–21 days), and 3 remodelling stage (>21 days).²

Clinical examination 

Quadriceps muscle contusion is easily accounted for by a history of blunt trauma. On clinical examination, there is usually discolouration of the skin, tenderness, swelling, and pain and tenderness of varying severity in association with a decreased range of movement and weight-bearing pain.

The diagnosis is made by questioning an accurate history from the patient and completing a physical examination.³

Thigh contusions typically present with pain that increases over the first 24-48 hours, exacerbated by dynamic movements and flexion of the knee. The patient can present with an antalgic gait, suggesting pain on weight-bearing. On palpation, there can be swelling, ecchymosis, point tenderness, and sometimes a palpable defect secondary to partial or complete muscle tear. Measurements of thigh circumference can show a greater firmness or swelling compared to the opposite side.⁴

The grading of quadriceps strength, especially against resistance, to both knee extension and hip flexion, is an important part of determining the severity of the injury as compared to the uninjured side. The knee flexion is also a predictive test in which decreased flexion is associated with greater severity on three grades: mild (Grade 1), moderate (Grade 2), and severe (Grade 3). Provocative testing, such as the active straight leg raise, is used to evaluate the integrity of the extensor mechanism, while careful distal neurovascular examination is needed to rule out the presence of thigh compartment syndrome.

The 'Lower Extremity Functional Scale' is used for measuring the limb function for a broad spectrum of lower limb conditions to determine if the patient is experiencing any difficulty with specific activities.⁵

Physical examination

The mechanism of injury is a compressive force blow to the thigh. This is usually going to cause disability that will not allow continued play, but most of the time the injury will be milder and will not be limiting until the play has been finished, when the bleeding and swelling have become severe enough to restrict. Trauma history with pain and limp is very common. Should treatment be delayed or the trauma be severe, compartment syndrome must be taken into consideration. Some very significant aspects of the history and physical findings in thigh muscle contusion are discussed. Alonso et al. created a prognostic algorithm, Trojian, to estimate the number of days to full training. Pertinent to the history is playing capacity following injury (yes or no within 5 minutes) and the hours following the injury to seek treatment. Pertinent on physical examination are: degrees of knee flexion in both lower extremities, injured muscle firmness rating between -5 and +5, and thigh circumference at the suprapatellar border in both lower extremities.⁶

Imaging examination

Magnetic resonance imaging (MRI) and diagnostic ultrasound are the best techniques for measuring soft tissue damage and complications caused by the initial injury. Both techniques have been highly sensitive to oedema and haemorrhage. These methods are rather expensive but can speed up the healing process of the injury by detecting the severity quickly.⁷

However, ultrasonography has a number of theoretical potential advantages over MRI, such as superior spatial resolution, cost, convenience, portability, and dynamic evaluation of the injury. In the present study by Megliola et al, comparing ultrasonography with MRI, 8 minor and 29 severe contusions (functional loss, strength reduction, muscle hypertonia, and increased muscle volume proportional to pain intensity) examined by ultrasonography performed after the injury, 6 to 72 hours after the injury, and by MRI within 5 days were studied.⁸

Ultrasonography detected all 29 severe contusions and 7 of the 8 minor contusions, but not the extra days. MRI was able to detect swelling and muscle injury that may have been missed on the initial ultrasonogram. Thus, ultrasonography seems to be an equal modality for diagnosing muscle contusion injury and has the added advantage of allowing aspiration of hematoma and serial evaluation. Ultrasonography should therefore be considered the first-line imaging modality in thigh contusion.⁹

In ultrasonography, thigh contusion is characterised by disruption of normal muscle architecture with ill-defined hypoechogenicity. The pattern may cross the fascial planes, as opposed to that of muscle strains. MRI will typically demonstrate a feathery pattern of diffuse oedema on short-tau inversion recovery and fat-suppressed T2-weighted images. Hematoma will appear hypoechogenic on ultrasonography but will demonstrate increased signal on MRI.

Acute hematomas (<48 hours) are typically isointense on T1-weighted images, and subacute hematomas (<30 days) are hyperintense relative to muscle on T1-weighted and fluid-sensitive sequences owing to the presence of methemoglobin.¹⁰

Differential diagnosis¹¹

Treatment and management of thigh contusions

Staged approach based on injury timeline

Immediate care (First 24 hours)

• Control bleeding and reduce secondary injury
• Flex and immobilise the knee at 120° with an elastic wrap or brace
• Crutches and maintains this position for 24 hours
• NSAIDs for only 48–72 hours

Acute phase

• Remove the brace and begin pain-free range-of-motion stretching
• Continue cryotherapy and NSAIDs (up to 72 hours)
• Crutches until knee flexion and quadriceps firmness match the uninjured side

Subacute phase

• Restore sport-specific mobility and agility
• Wear a modified thigh pad to prevent reinjury

Return to sport only if

• Pain-free knee flexion
• Quadriceps size/firmness restored
• Restored full mobility/agility

Adjunctive treatments

• NSAIDs: Safe in the short term (first 3 days), but may interfere with healing with long-term use
• Cryotherapy: Possibly reduces inflammation and tissue damage, but needs more research
• Corticosteroids: Possibly delays healing in contusions
• Suramin (experimental): Shows promise in animal studies but has not yet been tried in humans.
• Successful management entails progressive rehabilitation to restore function without permitting complications to arise¹²

Correlation between clinical findings and imaging

Initial evaluation and imaging choice

Clinical presentation is the major impetus for seeking imaging. Grade 1 injuries with little or no pain and intact knee flexion (>120°) rarely need imaging, as diagnosis is by history and physical examination. Injuries with moderate to severe pain, limited knee flexion (<120°), swelling, or palpable defects (Grades 2-3) usually need further evaluation. In these cases, MRI is the gold standard for measuring the degree of muscle tears, hematoma size, and oedema distribution, and ultrasound offers a cost-effective method of hematomas and aspiration guidance in acute settings.

Imaging modalities and their clinical correlates

MRI provides the most comprehensive evaluation, with results correlating with outcome in some cases. For example, central tendon injuries of rectus femoris on MRI correlate with recovery periods of 26+ days over peripheral tears (9 days). Oedema volume on T2-weighted MRI predicts rehabilitation time but is not a substitute for serial clinical examination. Ultrasound, although operator-dependent, provides dynamic imaging strongly correlated with the diagnosis and treatment of acute hematoma. 

It can direct needle aspiration or injection of corticosteroids with immediate impact on clinical care. X-rays and CT have a role in recognising complications such as myositis ossificans or excluding fracture in high-impact trauma, correlating with ongoing swelling, stiffness, and pain weeks after injury.⁸

Prognostic value and guidance for management

Clinical and imaging correlation has a major impact on prognosis and treatment planning. MRI results, including the amount of muscle oedema and involvement of the central tendon, predict extended return periods and direct more conservative treatment pathways. Detection and monitoring in real time with ultrasound of hematoma is linked with aspiration and return-to-play times. Having stated that, while imaging modalities provide useful data, serial clinical examinations, particularly those revealing changes in knee flexion, better predict recovery than single measurements using imaging. 

Complications and advanced imaging

Where clinical presentation suggests complications, imaging becomes essential for confirmation and management. In compartment syndrome, however, while MRI may show diffuse muscle oedema, the condition is ultimately diagnosed on clinical presentation (agonising pain, swollen tension, neurovascular compromise) and measurement of intra-compartmental pressure. Similarly, the development of myositis ossificans is initially suspected on clinical grounds but confirmed by imaging, with X-rays showing heterotopic ossification and MRI or CT showing early calcification.¹³

Conclusion

Diagnosis of thigh contusions is founded on the integration of clinical and imaging examinations, with each of them complementing the other in the grading of injury and management. Thigh contusion manifests clinically with pain, swelling, ecchymosis, and limitation in knee flexion, with grading based on the degree of functional impairment. Imaging is withheld for moderate to severe injury or if complications like myositis ossificans or compartment syndrome are suspected. MRI is the gold standard for the evaluation of muscle tear, oedema, and hematoma, whereas ultrasound is a cost-effective and dynamic modality for the detection and management of acute hematoma. X-rays are useful for fracture or heterotopic ossification detection in late presentations. In conclusion, clinical features are the basis of diagnosis and ongoing assessment, and imaging is an adjunct to enhance prognostic consideration and therapeutic treatment. A proper grasp of clinical and imaging data allows for precise diagnosis, successful management, and fruitful outcomes of recuperation.

Summary of key points

Epidemiology: Contusions of the thigh represent 12.1% of muscle injuries, with a higher incidence in males (15.1%) and competitive sports

• Clinical grading: Graded via knee flexion: Grade 1 (>120°), Grade 2 (90–120°), Grade 3 (<90°). Reduced flexion correlates with severity and duration of recovery

Imaging utility: MRI (gold standard) establishes muscle tear size and oedema; ultrasound identifies hematomas (97% sensitive for severe injury) and guides aspiration

• Phased treatment: Acute treatment: Immobilisation of the knee at 120°, RICE, NSAIDs (≤72 hours).

Rehabilitation: Progressive stretching, sport-specific agility, and return-to-play criteria (restored mobility, quadriceps firmness)

• Prognostic factors: Involvement of the central tendon on MRI signifies >26-day recovery. Serial clinical examination (e.g. improvement of knee flexion) is more useful than individual imaging tests in monitoring recovery