Flexor digitorum profundus laceration and reconstruction There are surgical changes relating to reconstruction of the flexor digitorum profundus of the fifth digit with increased signal intensity surrounding the reconstructed tendon as it courses through the flexor compartment. The tendon itself appears relatively normal in signal and caliber in this area and appears to be intact at least through the level of the mid diaphysis of the middle phalanx. Distal to this region, the tendon is difficult to visualize although there appear to be some fibers that reach the DIP joint. The extensor tendon is seen at the level of the MCP joint but becomes poorly visualized at the level of the PIP joint and further distally although it is again seen clearly distal to the DIP (series 5 image 17).The marrow signal intensity of the fifth finger is relatively normal and the DIP joint is preserved. Along the dorsal aspect of the DIP joint is a bilobed structure which demonstrates slight T1 hyperintensity and T2 hyperintensity which also contains small foci of low signal intensity centrally. This lesion in total measures approximately on 11 x 6 x 6 mm in the greatest transverse, AP, and craniocaudal dimensions and appears intimately associated with the base of the distal phalanx. Additionally, a second irregular and heterogeneous focus is identified within the soft tissues along the volar and ulnar aspect of the PIP joint which measures approximately 15 x 5 x 5 mm in the greatest craniocaudal and transaxial dimensions.The scapholunate and lunotriquetral ligaments are intact. The triangular fibrocartilage complex is intact. There is slight enlargement and increased signal intensity of the median nerve at the level of the hook of the hamate.
1. Surgical changes of the flexor digitorum profundus reconstruction of the fifth digit. Although the tendon itself appears relatively normal in signal intensity and caliber, there is increased signal intensity along the tendon sheath as courses through the flexor compartment and the tendon is poorly visualized distal to the middle phalanx and the presence of mild tenosynovitis and partial tearing cannot be excluded. There is also poor visualization of the extensor tendon between the levels of the PIP and DIP joint which concerning for at least partial tearing as well.2. Bilobed lesion within the dorsal soft tissues at the level of the DIP joint which is incompletely characterized on the exam given the lack of intravenous contrast. This lesion is nonspecific but may represent an epidermoid inclusion cyst or an area of surgical anchoring. There is an additional irregular focus within the volar soft tissues of the PIP joint of the fifth digit which is also nonspecific but may reflect scarring. These findings can be further evaluated with dedicated MRI of the fifth digit with and without contrast. Alternatively, ultrasound can be considered.