Modern magnetic resonance imaging (MRI) techniques and high-quality surface coils can provide exquisite anatomic detail of the small extremities such as the hands and feet. The fine soft tissue contrast resolution provided by MRI allows accurate identification and characterization of a variety of traumatic injuries, arthropathies, and neoplastic processes. Recent advances in gradient hardware, coil design and pulse sequences, as well as the proliferation of 3 T (3 T) MR units, allow very small field-of-view imaging at high resolution. The fine soft tissue contrast resolution of MRI allows assessment of the tendons, ligaments, and intricate pulley systems of the fingers. Normal tendons and ligaments of the hands typically demonstrate low signal intensity on MR imaging. In contrast, these structures exhibit increased signal intensity or abnormal morphology when injured .
This study included 42 patients, 33 males, 9 females, with age range from 11 to 56 years (mean age 35 years). All of them had history of trauma. This agreed with the study of De Jong et al. , which showed that mean age at the time of injury was 35.9 years (range 1–91 years). This corresponds to the age of the workforce most likely to have more physical labor-intensive occupations, which may place them at increased risk for injury.
The present study showed marked right-sided-hand affection (92.9%), while, on the other side, left-sided-hand affection represented by 7.1% only. This agreed with the study of De Jong et al.  that found that right-hand finger affection is about 91.4%, while the left-hand fingers were affected in only about 7.6% of cases.
In this study, striking male affection was noted reaching almost 78.5% of the reported cases with history of trauma and subsequent tendon or ligament injury proven by MRI. In contrast, only 21.5% of the cases were female. This agreed with the study of Kringstad et al. , which announced that males sustained more wounds from using hazardous equipment and thus have more severe injuries. Males have a significantly higher incidence of traumatic tendon injuries to the hand or wrist compared to females, a finding in accordance with previous studies. This may be partly due to the nature of gender-related professional work and recreational activities.
Our study showed that MRI can detect the exact site and level of tendon and ligament affection, which played a major role in correct surgical advancement and proper choice of the incision site. This agreed with the study of Jacob , which announced that advanced imaging with MRI is helpful to both confirm the diagnosis and accurately define the exact location of tendon injury for surgical planning.
The present study showed that in terms of finger affection, the middle finger and the thumb were the most injured fingers, 50% and 35.7%, respectively. This agreed with the study of De Jong et al.  that revealed marked affection of the thumb, index and middle finger in the study population, collectively about 68% of injured fingers.
This study showed that regarding the frequency and percentage of affection of the tendon or ligament in patients with history of trauma, ligamentous affection represented 57.1% of post-traumatic cases; meanwhile, tendons were affected in 42.9%. This agreed with the results of the study done by Woo et al.  who found that in the 50 patients with finger injuries, there were 33 cases of ligament injuries and 17 cases with tendon injuries.
Our study showed more affection of the flexor tendons (28.6%) compared to extensor tendons (14.3) as depicted by MRI. This was disagreeing with the results of the study of De Jong et al.  that showed extensor tendon injuries accounted for more injuries than flexor tendon injuries. In total, 395 extensor tendons and 297 flexor tendons of the hand were injured in that study. Extensor tendon injuries in the extensor zones of the fingers (namely zones I, II, III, IV, TI, TII and TIII) were about 33.4% of extensor tendon injuries of the hand, while injured cases at the flexor zones of the fingers (namely zones I, II, TI, TII) constituted about 27.6% of flexor tendon injuries of the hand. This may be attributed to his large study population.
This study showed that, in terms of flexor zones, flexor tendons of the fingers other than thumb showed affection of zone II (middle finger affected in 5 cases and little finger affection in 2 cases). Tendon retraction with gapping was noted in the affected flexor tendon of the little finger. Flexor tendons of the thumb were dominantly affected at zone T II (4 cases) and only 1 case at zone T I (at the level of distal portion of proximal phalanx). This agreed with the study of De Jong et al.  that found that of all flexor tendon zones, zone two was significantly more often than every other flexor zone. This was followed by zone I and zone T II.
The present study showed that the frequency and percentage of complete thickness tendon tear, as depicted by MRI, is represented by 33% and partial thickness tendon tear represented by 67%. This partially agreed with the 10-year study done by De Jong et al.  that involved 458 cases of acute traumatic tendon injuries of the hand with injuries affecting 692 tendons, of which 184 (26.6%) were reported to be only partially lacerated. This modest difference is related to the difference of the study population, as de Jong excluded the patient with closed tendon injury.
This study showed that MRI detection of the type of tendon tear is represented by 100% of the traumatic cases. This also almost agreeing with Gupta et al. , who reported that MRI allows diagnosis of complete or partial tendon tears, helps determine the location of the tears and the degree of tendon retraction, and helps exclude any associated avulsion fractures or other injuries. For these reasons, MRI is often used to classify and optimally manage these injuries.
In our study, the frequency and percentage of collateral ligament injury showed that radial collateral injury (of middle finger) was far common than ulnar collateral injury (of thumb) as depicted by MRI. Disruption of the proximal attachment of the radial collateral ligament of the middle finger with fluid signal fills the gap. Another case showed no definite proximal attachment of the medial collateral ligament of the thumb finger with replacement by fluid signal and associated mild metacarpophalangeal joint effusion. This agreed with Kadow and Fowler , who stated that MR imaging criteria for diagnosis of acute collateral ligament tears include discontinuity, detachment, or thickening of the ligament together with increased intraligamentous signal intensity on T2-weighted images, which is indicative of edema or hemorrhage. This also agreed with Gupta et al. , who reported that collateral ligament tears are typically seen at their proximal attachment. Forced ulnar deviation at the metacarpophalangeal joint may result in isolated tears of the radial collateral ligament. Isolated tears of the ulnar collateral ligaments at the metacarpophalangeal joint are relatively rare.
In the present study, MRI can detect bone marrow edema that was present in about 26.6% of the traumatic patients. This agreed with the study of Roemer et al.  that reported that subchondral bone marrow edema-like signal alterations exhibit typical signal characteristics on MRI and are common but nonspecific findings. MRI is the ideal tool to assess these pathologies as the subchondral bone marrow cannot be visualized by X-ray or ultrasound technology.
In our study, extensor system affection was noted in 14.3% of affected cases. Radial sagittal band affection with surrounding soft tissue edematous changes was noted. Also, lateral band of the extensor apparatus showed thinning out notably in T1WI denoting partial tear. This agreed with the study of Young et al.  that reported that injury of the radial sagittal band may result in ulnar subluxation of the extensor tendon. The degree of tendon instability is determined by the extent of sagittal band disruption. In a partial tear, a proximal tear rather than a distal tear of the sagittal band contributes to instability. In a complete tear, there is dislocation of the extensor tendon into the intermetacarpal space.