Ulnar Styloid Triquetral Impaction: Diagnosis and Treatment


Ulnar styloid triquetral impaction (USTI) is often unrecognized, yet it is a relatively common condition in which the ulnar styloid, or fragments of the ulnar styloid, impact into the triquetrum and produce localized pain and dysfunction. The syndrome occurs in supination. To achieve supination, the carpus and radius rotate around the ulnar head, placing the ulnar styloid more radial (more central) and therefore closer to the triquetrum) ( Figs. 49-1and 49-2 ). As seen on the lateral radiograph, the carpus is volar to the ulnar styloid ( Fig. 49-3 ). Dorsiflexion brings the triquetrum closer to the ulnar styloid. Therefore, combining these two positions means that the most likely position to produce impaction is dorsiflexion and supination. The provocative test, described by Topper and associates, consists of wrist dorsiflexion and pronation followed by rotation of the forearm into full supination while maintaining dorsiflexion ( Fig. 49-4 ). A similar position also occurs when one places the hand on the back pocket, repetitively turns pages, or forces the lower hand position in the “slap-shot,” as in ice hockey. Typically, pain is increased by direct palpation precisely over the tip of the ulnar styloid. This is best felt deep and volar to the extensor carpi ulnaris (ECU) tendon. Pain is not in the dorsal ulnocarpal interval unless ulnocarpal impaction (UCI) is also present.


Left wrist in supination and pronation shows the proximity of the ulnar styloid to the triquetrum in supination.


A coronal section of the left wrist is seen in supination and pronation. ECU, extensor carpi ulnaris; L, lunate; S, scaphoid; T, triquetrum; US, ulnar styloid.


Lateral view shows the ulnar styloid ( circle ) and illustrates why dorsiflexion of the carpus decreases the ulnar styloid–triquetral distance.


The ulnar styloid triquetral impaction provocative test begins on the left and proceeds to the right.

The diagnosis of USTI may be confused with that of UCI, which also presents as ulnar-sided pain. UCI is a consequence of ulnar head and lunate impaction. In the latter instance, the pain is ulnar and dorsal, increased by local palpation over the proximal ulnar aspect of lunate. The tenderness is not over the ulnar styloid. The provocative test, performed with the forearm in pronation and the wrist ulnarly deviated ( Fig. 49-5 ), is different from that carried out in USTI. Radiographic signs suggestive of USTI include ulnar styloid sclerosis, growth, flattening, small “kissing” cysts, and occasional loose bodies. A bone scan may show increased uptake about the styloid process. Magnetic resonance imaging (MRI) may show signal changes in the triquetrum, suggesting altered marrow vascularity and cystic reactive changes in the ulnar styloid. This is different from the MRI findings in UCI ( Fig. 49-6 ).


The grind test for ulnocarpal impaction is markedly different from that for ulnar styloid triquetral impaction.


MRI shows features of ulnocarpal impaction (UCI), ulnar styloid triquetral impaction (USTI), and a triangular fibrocartilage (TFC) tear.

Multiple pathologic processes can produce USTI. It is often present along with UCI. Successful treatment is therefore dependent on the cause of the USTI and whether UCI and distal radioulnar joint (DRUJ) arthritis are also present, since all the syndromes must be treated. The causes of USTI relate to anatomic and kinematic aspects that diminish the distance between the ulnar styloid and the triquetrum. There are four basic etiologic categories for USTI. Each category has subcategories in which different anatomic factors, pathologic causes, and carpal kinematics result in USTI. These categories relate to whatever aspect of the forearm-wrist complex is involved in the inappropriate motion or growth.

Category 1: Movement of Ulnar Styloid to Triquetrum

An example of a category 1 USTI can be seen in Figure 49-7 (blue arrow). The following are examples of involvements that can cause a category 1 USTI:

  • Congenitally long ulnar styloid . Not all styloids mature to the same length or shape ( Fig. 49-8 ). Lengths of the ulnar styloid vary considerably, ranging from 0 to 14.8 mm with an average length of 6.3 mm. A long ulnar styloid predisposes to USTI.

    FIGURE 49-8

    These previously untreated, uninjured ulnae show markedly different sizes of the ulnar styloid ( arrows ).

  • Growth of the ulnar styloid . After trauma, the ulnar styloid may increase in both length and width ( Fig. 49-9 A and B). In addition avulsed ulnar styloid fragments, which occur frequently, remain attached to the collateral ligament and adjacent soft tissues and increase in size ( Fig. 49-10 ). They are not free within the joint and frequently produce symptoms of impaction.

    FIGURE 49-9

    A, Both forearms show growth of the ulnar styloid on the left ( red arrows ). White arrow shows evidence of past trauma. B, Both forearms in supination show ulnar styloid triquetral impaction on the left ( arrow ).

    FIGURE 49-10

    Growth of an avulsed ulnar styloid fragment ( arrow ).

  • Longitudinal growth of the ulna . This is uncommon but was seen in a rare pagetoid involvement of the ulna and in the mosaic bone hypertrophy of Proteus syndrome. UCI was the main diagnosis, but USTI was also present.

  • Radial physeal growth arrest . In whole physis involvement, the distal radial physis slows in growth as a result of trauma, and the continuing normal distal ulnar physis growth produces a positive ulnar variance. This usually results in UCI or UCI plus USTI. Associated with the positive ulnar variance are a decrease in the inclination of the radius and—most important—a change in slope of the sigmoid notch. The sigmoid notch slopes so that the proximal end is closer to the ulna ( Fig. 49-11 ). In partial physis involvement, the volar ulnar-sided growth arrest in Madelung’s deformity results in a complex clinical situation in which both UCI and USTI coexist ( Fig. 49-12 ).

    FIGURE 49-11

    Both forearms show radial physeal growth arrest on the left with a positive ulnar variance, a change in sigmoid notch slope, and a decreased radial inclination.

    FIGURE 49-12

    Madelung’s deformity with ulnocarpal impaction and ulnar styloid triquetral impaction.


All four vectors participate in decreasing the distance between the ulnar styloid and the triquetrum.

Category 2: Movement of Triquetrum to Ulnar Styloid

An example of a category 2 USTI can be seen in Figure 49-7 (yellow arrow). This impaction occurs when the carpus moves proximally (as in collapse of the proximal carpal row), the radius moves proximally (as in distal radius malunions with a loss of radial length), the carpus ulnarly translocates, or the hand-wrist-radius complex moves ulnarly as one intact unit, which occurs after full or partial ulnar head excision ( Fig. 49-13 ). The following are possible causes of category 2 USTI:

  • Wrist arthrodesis . By removing articular cartilage and subchondral bone, this operation brings the triquetrum closer to the ulnar styloid, which may produce USTI that may be apparent only in supination ( Fig. 49-14 ).

    FIGURE 49-14

    Wrist arthrodesis with ulnar styloid triquetral impaction.

  • Kienböck’s disease . With collapse of the lunate, USTI may be present as a minor complaint along with symptoms related to Kienböck’s disease ( Fig. 49-15 ).

    FIGURE 49-15

    Kienböck’s disease with lunate collapse and ulnar styloid triquetral impaction. Red arrow points to larger space than yellow arrow.

  • Distal radius fractures (see Fig. 49-7 , white arrow). Radial shortening brings the carpus proximal and produces UCI and frequently USTI ( Fig. 49-16 ).

    FIGURE 49-16

    Both wrists with left post-distal radius fracture show shortening with ulnocarpal impaction and ulnar styloid triquetral impaction.

  • Ulnar translocation (see Fig. 49-7 , green arrow). This can occur with carpal translocation, in which translocation of the carpus ulnarly brings the lunate closer to the ulnar head and brings the triquetrum closer to the ulnar styloid. This rarely occurs with traumatic extrinsic wrist ligament insufficiency. It is common in patients with rheumatoid arthritis in which articular cartilage loss and resultant pseudoligamentous laxity allow the carpus to slide ulnarly ( Fig. 49-17 ). USTI can and often does occur, but in these situations it is rarely the patient’s major complaint. In addition, the carpus and radius may converge toward the ulna. If one excises the ulnar head transversely (Darrach procedure) or obliquely (matched hemiarthroplasty), the carpus and radius move toward the ulna. The latter procedure must incorporate a distal shortening of the ulna to prevent iatrogenic USTI from occurring (see Fig. 49-13 ).

    FIGURE 49-17

    Both wrists with rheumatoid involvement on the right show ulnocarpal impaction and ulnar styloid triquetral impaction with multiple vector causation.

  • Essex-Lopresti lesion (see Fig. 49-7 , white arrow). A radial head fracture, treated with excision and not replacement, may be associated with disruption of the DRUJ and radial shortening. This brings the carpus closer to the ulnar head and brings the triquetrum closer to the ulnar styloid. The syndromes of UCI and USTI may then coexist. Here, a radial head implant may be the treatment for USTI.

  • Rheumatoid arthritis . Diseases that produce loss of articular cartilage at both the radiocarpal and radiocapitellar joints result in the both radius and carpus moving proximally (see Fig. 49-17 ).

  • Radial growth abnormalities .

May be related to trauma, infection, and other rare causes such as enchondroma.

FIGURE 49-13

Matched hemiarthroplasty with radioulnar convergence and ulnar styloid triquetral impaction.

Category 3: Combination of Categories 1, 2, and 4

Multiple vectors may contribute to produce USTI (see Fig. 49-7 ). Frequently, an individual has more than one factor producing USTI. Figure 49-17 , already described, demonstrates all four vectors. The carpus has moved proximally. It has also moved ulnarly. There has been growth at the tip of the ulnar styloid. The radius has moved proximally. In this person, radiocarpal and UCI symptoms were much more troublesome than USTI symptoms; yet the USTI symptom complex was also present.

Category 4: Dynamic Impaction (with and without Predisposing Factors)

Occasionally, USTI may be present with no obvious predisposing factors. For instance, the ulnar styloid is not long, the ulnar variance is negative, and the radial head has not been excised ( Fig. 49-18 ). Patients may have experienced a single severe episode or repetitive episodes of trauma with the wrist positioned in supination and dorsiflexion.

FIGURE 49-18

Ulnar styloid triquetral impaction (arrow ) occurring in a patient with ligamentous laxity with no predisposing bony factors.


From the general film library, radiographs of a control group of 1000 patients showing no evidence of bony trauma were assessed for the average length of the ulnar styloid and the average projection of the styloid distal to the radius. Ulnar styloid length, measured from the base of the ulnar styloid to the tip in a line parallel with the long axis of the ulna, ranged from 0.0 to 14.80 mm with a mean of 6.31 mm and a standard deviation of 1.82 mm (n = 1000).

A prospective study of 56 patients with the clinical findings of USTI was completed in one surgeon’s (AAG) practice. Inclusion criteria required all three of the following: a history of ulnar wrist pain and a physical examination with both a positive USTI provocative test and tenderness localized precisely over the tip of the ulnar styloid. Frequently, USTI was not the major complaint, and more than one diagnosis was present. The additional diagnoses were based on clinical and radiographic findings. All patients underwent plain radiographic studies of the wrist. The radiographs were assessed for features that would cause a dynamic decrease in the ulnar styloid–triquetral interval.

In the latter group of 56 patients, other data included patient demographics and causative factors. The distribution of males and females was almost even (54% male, 46% female). Ages ranged from 15 to 69 years (mean 37 years). The patient’s dominant side was more often involved. One case was bilateral. Symptom duration ranged from 1.5 months to 6 years. A traumatic event was recalled in 38 of the 56 patients, 23 of which were fractures. Twenty-one (91%) of the fractures involved the distal radius, and most were associated with an ulnar styloid fracture. Twenty-four patients had an operative procedure to correct their problem. Seventeen operations consisted of ulnar styloid excision. Since USTI was often not the only diagnosis present, the other procedures performed included two radial osteotomies, one ulnar shortening, three matched hemiarthroplasties, and one Sauvé-Kapandji procedure. See Table 49-1 for patient demographics.

TABLE 49-1

Demographics of Patients with Ulnar Styloid Triquetral Impaction

Age (years) Gender Occupation Dominant Side Duration of Symptoms Traumatic Event/Cause Surgical Procedure/Treatment Classification
33 Male Laborer Yes 1 yr None Ulnar styloid resection 1A
47 Male Office job Yes 8 mo Forced twisting injury Ulnar styloid resection 1A
40 Male Restaurant worker 10 mo Fall None 1A
38 Female Dental hygienist None None 4
48 Male Bus driver Yes 6 mo Tennis related Ulnar styloid resection 4
46 Female Yes 10 mo Colles’ fracture Ulnar shortening 2C + 1B = 3
29 Female Police officer Yes 1 yr Injury on punching bag Ulnar styloid resection 1A
27 Male Contractor Yes AVN of lunate 5 yr before None 1A + 2B = 3
40 Male Sheet metal worker No 7 mo Injury lifting weights Ulnar styloid resection 1A
21 Male Student Yes Throwing a ball Excision of ulnar styloid and matched hemiarthroplasty 1B
22 Male Hockey player Yes 2.5 mo Hockey—wrist shot None 4
49 Male Forklift driver Injured arm driving forklift Ulnar styloid resection 2C + 1B = 3
32 Female Phys. ed. teacher Yes 1 yr Fracture of distal radius None 2C + 1B = 3
33 Female Homemaker No 3 mo Surgery as a child, volleyball injury None 2C + 1D = 3
56 Female Office worker Yes 6 mo Colles’ fracture Ulnar styloid resection 2C + 1B = 3
35 Male No 5 mo Distal radius fracture None 1A + 2C = 3
45 Female Nurse Yes 5 mo Lifting bed rail None 4
64 Female Yes 1 yr Distal radius fracture Distal radial osteotomy 2C
45 Male Laborer 3 mo Injury lifting a window None 1B
52 Female Homemaker 2 mo Distal radius fracture None 2C
31 Female Yes 8 mo None Ulnar styloid resection 4
17 Male Student No SH II of distal radius None 1D + 1B = 3
17 Male Student 7 mo Fracture of distal radius None 2C
26 Male 3 yr Radial head excision for fracture Excision of ulnar styloid with TFCC repair; Sauvé-Kapandji procedure 2E
32 Female Office clerk Yes 3 mo MVC Ulnar styloid resection 1A
62 Female Nurse Yes 1 yr None None 2F + 2D = 3
28 Male 3 yr Perilunate dislocation with subsequent fusion Excision of ulnar styloid 2A
46 Female 1 yr Fracture of distal radius Matched hemiarthroplasty 2D
52 Male Construction Yes Fracture of distal radius and ulnar styloid None 2C
31 Female Typist No 1 yr Fracture of distal radius 4 yr before. Reinjury with twisting force None 1B + 2C = 3
40 Male Home renovator Yes 11 mo MVC None 4
19 Male Hockey player A few months None None 4
69 Male Retired engineer 1 yr Wrist injury at 13 yr of age None 1B
45 Female No 2 yr Fracture of distal radius None 2C
47 Female Yes 6 mo Osteotomy and excision of ulnar head 15 yr earlier Planned Sauvé-Kapandji 1D + 2G = 3
15 Male Student No SH II fracture of distal radius 2 yr earlier None 1D
46 Female Lab. technician Yes 1.5 mo None None 4
46 Female Hospital worker 4 mo Fracture of distal radius and ulnar styloid None 1B + 2C = 3
50 Female Yes Fracture of distal radius and ulnar styloid None 1B + 2C = 3
28 Female Scrub nurse Yes Previous fracture of ulnar styloid Ulnar styloid resection, arthrotomy of wrist with loose body excision 1B
36 Male Technologist Yes 2 yr Wrist fracture with closed management None 1B
45 Male Mechanic Yes Wrist fracture 20 yr earlier, followed by excision of lunate 19 yr earlier, followed by arthrodesis None 2A
63 Female Not working No 2 yr Previous undisplaced fracture of distal radius None 2C
41 Female Nurse Injury with patient transfer Excision of ulnar styloid 1B
17 Male Student No Football injury Excision of ulnar styloid 1B
17 Female Student Bilateral 2 yr None None 1D
32 Male Carpenter Yes MVC with Galeazzi fracture and avulsion of ulnar styloid Excision of ulnar styloid 1B
33 Male Unemployed No Distal radius fracture Radial osteotomy 2C
34 Female 6 yr Fall from horse None 4
22 Male Construction Yes 2 yr Distal radius fracture None 1B
16 Male Student No 1 yr Hockey—lower hand Injection 1A + 4
30 Female Mechanic Yes 2 yr Distal radius fracture Excision 1B
56 Female Secretary No 1.5 yr Distal radius fracture Matched hemiarthroplasty 2C
33 Male Physical therapist No 2 yr Forced dorsiflexion in supination None 4
23 Male Hockey player Yes 2 yr Forced dorsiflexion in supination Excision 4
54 Male Cook No 2 yr None 1A

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Jul 10, 2019 | Posted by in ORTHOPEDIC | Comments Off on Ulnar Styloid Triquetral Impaction: Diagnosis and Treatment
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