Tommy Lindau and Andrew J. Logan
DEFINITION
The distal ulna is the fixed point3 around which the radius and the hand function (FIG 1A).
Fractures of the distal ulna are often inadequately treated in comparison to its larger counterpart, the radius (FIG 1B,C).
The current literature gives little guidance as to the management of these fractures and associated injuries.
ANATOMY
The ulnar head forms the fixed point on which the hand and radius rest3 (FIG 2A).
The radius rotates around the ulnar head through the distal radioulnar joint (DRUJ) during forearm pronation and supination.3,4
This joint is connected to the carpus by a complicated ligament apparatus, the triangular fibrocartilage complex (TFCC).
The stability of the DRUJ is achieved through bony congruity between the sigmoid notch of the radius and the ulnar head supported by the ulnoradial ligaments1,4 (FIG 2B).
The spheres of the two articular surfaces differ (FIG 2C).
Sixty percent of the joint surfaces are in contact in neutral forearm position.1
In full pronation and supination there is only 10% bony contact.1
The ligaments run from the fovea of the ulnar head and the base of the ulnar styloid to the dorsal and palmar edges of the sigmoid notch on the distal radius1,9 (FIG 2B).
PATHOGENESIS
Isolated ulnar fractures most commonly occur when the forearm is struck by an object, explaining the eponym “nightstick fracture.”
Distal ulnar fractures are most often due to a fall on an outstretched hand.
It is a common understanding that ulnar-sided injuries are more often caused by falls backward in which the forearm is in supination, loading the ulnar side of the distal forearm and wrist and causing distal ulnar fractures, triquetral chip fractures, TFCC injuries, and so forth.
In contrast, radial-sided injuries are more often caused by falls forward, loading the radial side of the forearm and wrist and causing scaphoid fractures, distal radius fractures, and so forth.
NATURAL HISTORY
Many distal ulnar fractures leave only marginal long-term problems.
Some distal ulnar malunions cause DRUJ incongruency with subsequent instability or blocked forearm rotation (FIG 3). This is why management of these deceptive fractures is important.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Posteroanterior, lateral, and oblique radiographs typically reveal the pathology.
FIG 1 • A. The distal ulna is the fixed point upon which performance of most daily hand activities depends. B,C. Fractures of the distal ulna are often neglected in comparison to those of its larger counterpart, the radius, which always attracts attention and treatment efforts. The outcome after distal forearm fractures could be improved if the fixed point—the distal ulna—is addressed surgically at the same time as the radius is operated on.
FIG 2 • A. The distal ulna is the fixed point around which the radius rotates in pronation and supination. Through the ulnocarpal ligament the distal ulna relates to the hand, allowing daily hand activities. B.The distal radioulnar joint is stable because of bony congruity between the ulnar head and the sigmoid notch on the radius. The ulnoradial ligament inserts in the fovea and the base of the ulnar styloid and has a dorsal and palmar ligament attached to the dorsal and palmar part of the sigmoid notch respectively. They act as reins in the pronation and supination motion. C. The spheres of the two articular surfaces differ: the curvature of the ulnar head has a shorter radius, whereas the curvature of the sigmoid notch has a greater radius.
FIG 3 • A,B. Radiographs showing a distal radius fracture together with an ulnar head and styloid fracture. The complexity of the ulnar-sided injury was underappreciated. C. Intraoperative fluoroscopic image after fixation of the distal radius fracture, revealing displaced and unstable ulnar fractures. (continued)
FIG 3 • (continued) D,E. The distal radius fracture was stabilized using a volar locking plate. The ulnar head and styloid fractures were partially reduced and fixed with two Kirschner wires. The surgeon adequately secured the ulnar styloid fracture but not the ulnar head fracture and postoperatively did not restrict forearm rotation. F,G. These radiographs reveal the eventual ulnar head malunion that resulted in distal radioulnar joint instability and diminished forearm rotation. The situation was salvaged using an ulnar head replacement prosthesis.
CT is useful in examining articular fractures of the ulnar head.
MRI is sometimes needed to evaluate the integrity of the TFCC.
Arthroscopy should be considered if a radiograph leads the physician to suspect DRUJ dissociation without radiographic explanations, such as a displaced ulnar styloid base fracture.
SURGICAL MANAGEMENT
Findings and Indications DRUJ Dissociation
Radiographs occasionally reveal DRUJ dissociation in the absence of an ulnar-sided fracture (FIG 4). This results from detachment of the ulnoradial ligament8 (FIG 5A).
Such ulnoradial ligament injuries have been found to cause DRUJ laxity and a worse outcome after distal radius fractures in patients without osteoporosis7 (FIG 5B).
Arthroscopically assisted repair or open repair and reattachment of the ulnoradial ligament to the fovea of the ulnar head are required to restore stability in the DRUJ (FIG 5C) (see Chap. HA-49).
Ulnar Styloid Fractures
The importance of ulnar styloid fractures and the need for operative intervention depends on the involvement of the ulnoradial ligament insertion site around the fovea of the ulnar head at the base of the styloid (FIG 6A).
Generally, ulnar styloid fractures should be operated on if the fracture is at the base of the ulnar styloid and is displaced more than 2 mm11 (FIG 6B,C).
Radial translation of the fractured ulnar styloid is caused by the detachment of the ulnoradial ligament. This increases the indication (FIG 6D) more than axial, distal fracture displacement (detaching the ulnotriquetral collateral ligament).
Ulnar styloid fractures at the tip are likely to be stable and do not require fixation, as the ulnoradial ligament remains attached to the ulnar head at the base of the styloid (FIG 6E,F).
Ulnar-sided injuries associated with distal radius fractures should be carefully assessed radiographically and clinically after open reduction and internal fixation (ORIF) of the radius fracture.
Ulnar fracture reduction and DRUJ joint stability are often improved after treatment of the radius fracture.
Stable DRUJ means that the ulnoradial ligament is not attached to the fractured ulnar styloid and therefore can be treated nonoperatively.
Unstable DRUJ indicates that the ulnoradial ligament is detached with the styloid fracture. The styloid should be reduced and stabilized or the ligament reattached.
FIG 4 • A. An undisplaced distal radius fracture with no obvious distal ulna pathology. B. The same fracture with a stress test to the distal radioulnar joint (DRUJ), and an obvious DRUJ dissociation is seen as a sign of a complete ulnoradial ligament detachment in the absence of an ulnar styloid fracture.
FIG 5 • A. Arthroscopic view of an ulnoradial (peripheral triangular fibrocartilage complex) detachment. The lunate is seen at the top, the radius below, and the detached surface with bleeding at the right side. B. Distal radioulnar joint dissociation after a distal radius fracture with a complete detachment of the ulnoradial ligament in the absence of any ulnar-sided fracture. C. Arthroscopic view of an arthroscopically assisted repair and reattachment of an avulsed ulnoradial ligament. The lunotriquetral interval is seen on top, the radius joint surface is seen in the lower left corner, and the blue sutures are bringing down the ligament toward the fovea of the ulnar head, which is not seen arthroscopically.
FIG 6 • A. The ulnoradial ligament has superficial and deeper components, which insert at the fovea of the ulnar head and partly attach to the base of the ulnar styloid. Consequently, a fracture at the base of the ulnar styloid may or may not detach the main distal radioulnar joint-stabilizing ligament. B,C. Ulnar styloid fractures at the base may detach the ulnoradial ligament and should be operated on if they are displaced more than 2 mm.11 D. Radial displacement (detaching the ulnoradial ligament) increases the indication for surgical treatment. E,F. Ulnar styloid tip fractures represent avulsion fractures from the ulnotriquetral collateral ligament. They demand no further treatment.
FIG 7 • A,B. Abutment of the ulnar styloid into the triquetrum on the ulnar side of the carpus. C,D. An ulnar styloid nonunion causing problems as a loose body.
Ulnar Styloid Nonunion
The main physical findings of ulnar styloid nonunion are ulnar-sided wrist pain worse with loading in rotation and tenderness over the ulnar styloid.5 Symptoms from an ulnar styloid nonunion are related to the following:
DRUJ instability from a malfunctioning ulnoradial ligament (peripheral TFCC detachment)5 (Fig 5B)
Impingement of the overlying extensor carpi ulnaris (ECU) tendon
Abutment on the carpus5 (FIG 7A,B)
Soft tissue irritation from the loose body (FIG 7C,D)
Ulnar Head Fractures
Ulnar head fractures are most often associated with distal radius fractures, and the pattern of the distal radius fracture will have a strong influence on the overall functional outcome.
Ulnar head fractures are seen either alone or with involvement of extra-articular portions of the distal ulna, proximally toward the diaphysis or distally including the styloid (Fig 3A,B).
Distal Ulnar Neck and Shaft Fractures
A distal ulnar neck or distal shaft fracture is a fracture that occurs within 4 cm of the distal dome of the ulnar head (FIG 8A–D).
FIG 8 • A,B. This ulnar shaft fracture is by definition within 4 cm of the distal dome of the ulnar head. C,D. This ulnar shaft fracture is more proximal and should be considered an isolated ulnar fracture. However, there may still be involvement in the distal radioulnar joint (DRUJ), which needs to be taken into account. The DRUJ should be examined for stability after open reduction and internal fixation. (continued)
FIG 8 • (continued) E,F. Unstable distal radius and ulnar fractures are difficult to immobilize with casts alone. AP and lateral views show comminution and dorsal displacement in both fractures. This fracture cannot be treated conservatively.
Some distal ulnar fractures in association with distal radius fractures realign after manipulation and are considered to be stable once the radius is reduced.10
It is difficult to immobilize unstable fractures with a cast alone. Three-point fixation, even in an above-elbow cast, is not effective (FIG 8E,F).
Comminuted Intra-Articular Distal Ulnar Fractures
Comminuted distal ulnar fractures that are irreducible and cannot be reconstructed have been mentioned in the literature in only one case report.2
It is generally recommended that the initial approach be geared toward restoring the anatomy and maintaining the overall alignment of the ulna and DRUJ.
Approach
The described approach is used for all distal ulnar fractures, including the ones extending into the neck of the ulna and into the distal shaft.
This approach can, for instance, access an ulnar styloid fracture or nonunion and at the same time visualize, assess, and allow treatment of any associated TFCC pathology.
TECHNIQUES
INCISION AND EXPOSURE
Approach the distal ulna through a dorsal zigzag incision centered over the DRUJ (TECH FIG 1A,B).
This approach allows reattachment of all crucial stabilizing structures at the time of wound closure.
Carefully protect the dorsal sensory branches of the ulnar nerve (TECH FIG 1C).
Incise the retinaculum overlying the fifth extensor compartment (TECH FIG 1D).
Elevate the ulnar retinacular flap in the interval between the extensor retinaculum and the separate dorsal sheet for the ECU tendon.
Preserve the integrity of the separate ECU compartment (TECH FIG 1E).
Open the dorsal capsule of the DRUJ using an ulnarly based flap raised from the 4–5 septum (TECH FIG 1F).
Identify the 4–5 intercompartmental artery.
TECH FIG 1 • Surgical approach to all distal ulnar fractures. A,B. A dorsal zigzag incision is made with the center directed toward the distal radioulnar joint. (continued)
TECH FIG 1 • (continued) C. Subcutaneous dissection should be performed so that the dorsal cutaneous branch from the ulnar nerve is protected. D. The retinaculum is identified and an approach through the fifth extensor compartment is done. E. The retinaculum is elevated as an ulnarly based flap between the true retinaculum and the separate dorsal sheet for the extensor carpi ulnaris (ECU) tendon (which should be preserved). The ECU is thereby kept in its tendon sheath. F. An ulnarly based capsular flap is raised from the 4–5 septum to gain access to the distal ulna. G. As shown in this dissected specimen, the ulnocarpal joint is often hidden behind the synovium over the meniscus homolog. (C,D: Courtesy of M. Garcia-Elias, Spain.)
Begin the capsular incision at the neck of the ulna and extend it to the 4–5 intercompartmental artery, which is diathermied.
The incision continues along this line to the level of the radiocarpal joint, where it then extends distally and ulnarly along the dorsal radiotriquetral ligament to the triquetrum.
By staying in a flat layer along the dorsal cortex of the radius, the dorsal ulnoradial ligament attachment is not violated.
The DRUJ and the spanning TFCC are then readily visualized. The ulnocarpal joint is often hidden behind the synovium over the meniscus homolog (TECH FIG 1G).
If required, remove the synovium dorsal to the ulnoradial ligament to gain access to the ulnar styloid and the ulnocarpal joint.
In cases of a distal neck fracture without any intraarticular involvement or soft tissue components, the approach stays proximal to the capsular flap. However, the retinacular flap needs to be raised to address the distal metaphyseal fractures.
ULNAR STYLOID FRACTURES
Options for fixation of ulnar styloid base fractures include the following:
Single or double Kirschner wires (TECH FIG 2A,B)
Tension band wiring (TECH FIG 2C)
Wire loop or suture
Screw fixation (TECH FIG 2D)
TECH FIG 2 • The ulnar styloid can be fixed in various ways to secure reattachment of the ulnoradial ligament and thereby stabilize the distal radioulnar joint. A,B. Single (not rotationally stable) or double Kirschner wires. C. Tension band wiring. D. Screw fixation (not rotationally stable).
ULNAR STYLOID NONUNIONS
Reattachment of the nonunited fragment to the ulnar head is indicated if the fragment is large.5
If the fragment is small, it should be excised and the ulnoradial ligament reattached directly to the fovea of the ulnar head.5
If the fragment is small and located distally and there is no DRUJ instability, the ulnar styloid can be excised without any associated ligament procedure.5
ULNAR HEAD FRACTURES
The intra-articular component is reduced and stabilized.
If the extra-articular component extends proximally toward the neck of the distal ulna a condylar blade plate is recommended (TECH FIG 3), whereas tension band wiring is recommended if the extra-articular component involves the ulnar styloid (Tech Fig 2C).
Immobilization after fixation depends on the stability of the fracture and its fixation.
Ulnar head fractures without a proximal extra-articular component
Fractures that are displaced (with an intra-articular stepoff) or unstable are treated with ORIF using buried headless compression screws6 or Kirschner wires.
Immobilization after fixation depends on the stability of the fracture and its fixation.
Ulnar head fractures with a proximal extra-articular component
TECH FIG 3 • Irreducible or unstable distal forearm fractures require open reduction and internal fixation.10 AP and lateral radiographs show a dorsally displaced distal forearm fracture fixed with a blade plate.
Irreducible or unstable fractures require ORIF. 10
This can be achieved using either a condylar blade plate10 (Tech Fig 3) or tension band wiring supplemented by intrafragmentary screws (TECH FIG 4).
TECH FIG 4 • A,B. AP and lateral radiographs show a dorsally displaced distal forearm fracture. Open reduction and internal fixation was performed using both a dorsoradial and a dorsoulnar approach to stabilize the fractures. C. Because of the comminution around the ulnar styloid base, fixation was achieved with a suture loop.
COMMINUTED INTRA-ARTICULAR DISTAL ULNAR FRACTURES
Three treatment options exist for comminuted intraarticular distal ulnar fractures:
Restoration of the anatomy and overall alignment of the ulna and DRUJ as mentioned above
This can be accomplished with manipulation and above-elbow cast immobilization alone or alternatively by surgical means with temporary wiring or external fixation.
The potential problems with this management technique are wrist stiffness and reduced forearm rotation that may not be corrected with a late salvage procedure.
Primary distal ulnar head replacement2
The theoretical advantage is reduced stiffness (from having early movement) and less DRUJ pain.
Total or partial excision of the ulnar head as well as DRUJ arthrodesis with distal ulnar neck resection (Sauve-Kapandji procedure)
POSTOPERATIVE CARE
Stable fixation of the distal ulnar complex still requires protection postoperatively with a below-elbow splint.
Intermediate stable fixation requires 4 weeks of protection using a sugartong-type splint to allow flexion and extension of the elbow but protect against uncontrolled pronation and supination.
Unstable fixation after internal, external, or nonoperative treatment requires above-elbow protection in neutral forearm rotation to limit movement for the first 6 weeks. There is otherwise a risk that rotational forces will cause a nonunion or malunion.
OUTCOMES
Outcome is influenced by the fact that most distal ulnar fractures are neglected in comparison to the more common and more extensively treated distal radius fractures.
The outcome can surely be improved if distal ulnar fractures are treated more directly and aggressively.
The outcome will also improve if the relationship between the ulnar styloid and the ulnoradial ligament is fully understood and addressed.
COMPLICATIONS
Stiffness of the DRUJ with limited pronation and supination
Infection
Nonunion
Malunion
REFERENCES
1. af Ekenstam F, Hagert CG. Anatomical studies on the geometry and stability of the distal radio ulnar joint. Scand J Plast Reconstr Surg 1985;19:17–25.
2. Grechenig W, Peicha G, Fellinger M. Primary ulnar head prosthesis for the treatment of an irreparable ulnar head fracture dislocation. J Hand Surg Br 2001;26B:269–271.
3. Hagert CG. The distal radioulnar joint in relation to the whole forearm. Clin Orthop Relat Res 1992;275:56–64.
4. Hagert CG. Current concepts of the functional anatomy of the distal radioulnar joint, including the ulnocarpal junction. In: Büchler U, ed. Wrist Instability. Berlin: Martin Dunitz, 1996:15–21.
5. Hauck RM, Skahen III J, Palmer AK. Classification and treatment of ulnar styloid nonunion. J Hand Surg Am 1996;21A:418–422.
6. Jakab E, Ganos DL, Gagnon S. Isolated intra-articular fractures of the ulnar head. J Orthop Trauma 1993;7:290–292.
7. Lindau T, Adlercreutz C, Aspenberg P. Peripheral tears of the triangular fibrocartilage complex cause distal radioulnar instability after distal radius fractures. J Hand Surg Am 2000;25A:464–468.
8. Lindau T, Arner M, Hagberg L. Intraarticular lesions in distal fractures of the radius in young adults: a descriptive arthroscopic study in 50 patients. J Hand Surg Br 1997;22B:638–643.
9. Palmer AK, Werner FW. The triangular fibrocartilage complex of the wrist: anatomy and function. J Hand Surg Am 1981;6A: 153–162.
10. Ring D, McCarty PL, Campbell D, et al. Condylar blade plate fixation of unstable fractures of the distal ulna associated with fractures of the distal radius. J Hand Surg Am 2004;29A:103–109.
11. May MM, Lawton JN, Blazar PE. Ulnar styloid fractures associated with distal radius fractures: incidence and implications for distal radioulnar joint instability. J Hand Surg Am 2002; 27A:965–971.