Traumatic wrist lesions occur frequently. Subsequently, secondary abutment syndromes (SAS), a common cause of incapacitating pain and limited range of motion in spite of minimal or absent alterations on radiographs, may arise. They are often underappreciated due to the complex wrist anatomy and call for a thorough analysis of all wrist components.
The aim of this pictorial review is to present an overview of SAS and to highlight the role of imaging.
The wrist is a complex structure of cartilaginous joints with little intrinsic stability, but mainly relies on soft tissue constraints from various ligaments. The three-dimensional motion is very susceptible to disturbances of their complex surfaces and to ligamentous lesions .
Biomechanics and pathology
Wrist fractures are frequently missed on radiographs . Ligamentous lesions  are even more susceptible to false negative interpretations. Both may be the cause of misalignment, pathological mobility or instability.
The secondary repetitive bony impaction may result in contusion  with the development of subchondral bone marrow oedema (BMO), opposing articular surfaces chondromalacia, subchondral cyst formation, and surrounding synovitis.
SAS may give rise to complaints, sometimes appearing years after trauma. The predominant symptoms are restricted motion and incapacitating pain, exacerbated by activity. SAS may have a negative impact on the three-dimensional hand positioning during daily activities .
Pathology and imaging
Intra-articular fractures of the radius may heal with a residual step-off , seen on radiographs, CT, and MRI (Figure 1A–C). The radial deviation is limited. MRI illustrates the disappeared cartilage (Figure 1A and B) or the surface disruption (Figure 1C). In radial deviation (Figure 1B), bumping of the scaphoid against the prominent radial fossa zone causes repetitive impaction, resulting in BMO.
Lunate bone impaction on its articular fossa may cause SAS. Parasagittal radial fractures (Figure 1D) need careful follow-up by radiographs or CT  in order to detect displacements, possibly causing SAS (Figure 1E and F) and limiting the ulnar deviation (Figure 1F).
Distal radioulnar joint (DRUJ) fractures are difficult to evaluate on radiographs, particularly coronal sigmoid notch fractures (Figure 2A and B). Bony incongruity is better evaluated by (cone beam-)CT and a cartilage step-off (Figure 2C and D) by MRI. Pronation and supination may be hampered during the radial movement around the ulna . Even minor deformities may cause severe dysfunction.
A relative ulnar shortening may appear after trauma, causing a DRUJ impingement (Figure 2E and F). Excessive ulnar shortening or resection may cause secondary impingement . The appearance is equal to a congenital short ulna.
Ulnar (intra)styloid abutment
Styloid process fractures may fail to heal, resulting into fragmentation and collision during ulnar deviation. MRI highlights neo-articulation and BMO (Figure 3A–C). The triangular fibrocartilage complex (TFCC) ulnar insertion (fovea and tip) in relation to these fragments is depicted (Figure 3B). Basal fractures may lead to DRUJ instability [9, 10]. Ultrasound or MRI performed in pronation and supination may confirm a dynamic extensor carpi ulnaris tendon dislocation (empty sulcus sign).
Due to styloid process length increase, impaction with the triquetral bone may appear (Figure 3D–G). As in the classical abutment, the Garcia-Elias index  may indicate the risk of SAS development. Surrounding synovitis is frequent (prestyloidal synovitis).
Ulnolunate and/or ulnotriquetral abutment
In secondary positive ulnar variance, the latter abuts the lunate and/or triquetral bone and eventually leads to ulnar head deformation (Figure 4A–B). It may be associated with a TFCC tear. A lengthening of more than 3 mm may be symptomatic (Hulten criteria) . TFCC lesions and BMO typically at the proximal-ulnar corner of the lunate bone are revealed early by MRI (Figure 4C–E).
Ulnar translation with abutment
Extensive destruction of extrinsic ligaments leads to a proximal-ulnar carpal shift , creating a reversed status compared to ulnar abutment (ulna approaches carpus). The lateral widening of the radioscaphoid joint and the lunate position versus its corresponding articular fossa (less than 50% overlap in neutral position) are hallmarks on radiographs (Figure 5A). MRI presents the cartilage destruction, BMO, and eventual TFCC lesions (Figure 5B and C).
Fractures appear most frequently at the scaphoid waist . Radial deviation gives an impaction at a pseudarthrosis. Contact zone deformation (Figure 6A and B) and mobility between the fragments are illustrated on radiographs. BMO and extrinsic ligamentous lesions are delineated by MRI.
Avascular necrosis – probably due to chronic microtraumata – with deformation starts at the radial side . Due to the height loss, the ulnar side approaches the ulna (reversed situation of ulnar abutment) (Figure 7A). The normal ulnar variance and the late appearance of sclerotic borders may be observed on radiographs. Early BMO and TFCC lesions call for MRI (Figure 7B and C).
On radiographs (Figure 8A), a widened joint space (≥3 mm)  in rest or under stress (Schneck view) may be observed. MRI may show the ligamentous tear (Figure 8B) and the juxta-articular band shaped BMO (Figure 8C).
MRI may also show this ligamentous tear (Figure 8D) and the band-shaped BMO (Figure 8E). Eventual concurrent extrinsic ligamentous lesions should be looked for, as it is questionable if this solitary lesion results in abnormal mobility . Due to chronic impaction, massive deformation may appear on radiographs (Figure 8F).
Hamatolunar abutment is related to lunate bony variants (Viegas type II). However, a posttraumatic disturbance of the carpal row alignment (Gilula)  may induce SAS. Radiographs reveal the deformed area with abnormal contact during ulnar deviation (Figure 9A and B). The carpal line interruption and the pathologic bone motions are obvious on mobility radiographs.
A large variety of pathologies may cause SAS. This underscores the need for a thorough posttraumatic joint evaluation. Follow-up radiographs and MRI are mandatory in the presence of clinical symptoms. Concerns about the prognosis – certainly in expert or insurance-related files – should encourage detailed assessment, as even small lesions may be very functionally disabling.
Important teaching points
Posttraumatic SAS may interfere with a large variety of normal daily activities, as the wrist is a crucial structure in the three-dimensional positioning of the hand. Some are fairly unknown and, due the complex anatomy of the wrist, a SAS is also often ignored or underappreciated.