1 Introduction

The wrist represents a complex joint consisting of multiple articulations constrained by an intricate ligamentous network. As such, the orthopedic aphorism that “a fracture is a soft-tissue injury with a broken bone” has special relevance when considering fractures of the distal radius and carpus. Despite the relative frequency of distal radius fractures, the concomitant ligamentous trauma hidden within the radiograph has only been fully appreciated in recent decades and can still be easily overlooked.

Multiple articulations that comprise the wrist allow for both biplanar (i.e. flexion-extension, radial-ulnar deviation), as well as multiplanar movement (i.e. dart-throwers motion, circumduction). Furthermore, the distal radioulnar joint (DRUJ), which is functionally and anatomically integrated with the ulnocarpal articulation of the wrist, allows for forearm pronosupination.¹ To execute these complex movements under weightbearing conditions, the carpus and distal forearm rely upon multiple critical ligaments to resist abnormal posture and transfer load from the hand to the more proximal extremity. Consequently, when a force surpasses the limits of what the wrist can withstand, a range of injuries can occur – from simple extraarticular fractures to complex carpal dislocations. In reality, a wide spectrum of osseous and ligamentous pathology can be found after injury.

Several studies have independently confirmed a high incidence of concomitant soft tissue injuries occurring with distal radius fractures. Such injuries include traumatic tears of the triangular fibrocartilage, as well as radiocarpal, ulnocarpal, and intercarpal ligaments. Timely recognition and treatment of bony and often subtle ligamentous injuries is critical to avoid future instability and wrist dysfunction. Arthroscopy may play a key role in these underrecognized fracture patterns, both providing an accurate means of diagnosis and simultaneous method of treatment.^2–5 In this article we present principles for the arthroscopic evaluation of such injuries.

2 Pathomechanics of ligamentous injury in distal radius fractures

Several systems for classifying distal radius fractures have been developed, each with varying anatomic, diagnostic, and treatment considerations. Fernandez subdivided fractures into bending, shearing, compression, avulsion, and combination mechanisms that are recognizable on standard radiographs.⁶ Type IV (avulsion or radiocarpal fracture dislocations) and type V (combination high velocity) patterns are most concerning for ligamentous injury. The Fernandez classification also separately describes the stability of the DRUJ, and by proxy, the integrity of the ligamentous portions of the TFCC.

The pathomechanics of injury is dependent on the wrist position, direction and magnitude of force, and bone quality. Radiographic features of distal radius fractures have been correlated to distinct patterns of carpal instability, which include scapholunate dissociation, dorsal intercalated segmental instability (DISI), volar intercalated segmental instability (VISI), and dorsal, palmar, and ulnar translocation.⁷ The role of extrinsic carpal ligament disruption with distal radius fractures leading to non-dissociative carpal instability (CIND) has been recently studied.^8,9 CIND-VISI is associated with dorsal ligament failure at the radiocarpal joint and volar ligament failure at the midcarpal joint. CIND-DISI is associated with an inverse pattern of extrinsic ligament failure.

An axial compression mechanism is more frequently associated with isolated SL dissociation – thought to be the result of SLIL and radioscapholunate ligament disruption.¹⁰ Accordingly, die punch fractures, type B fractures, volar marginal rim, four-part intra-articular fractures, and impaction with a >2 mm change in ulnar variance are associated with a greater risk of high-grade SLIL injury.^11–14

The association of distal radius fractures with other acute carpal dislocations has also been elucidated. Mayfield and colleagues originally described two distinct patterns of complex carpal injury that propagate through the ligaments of the intercarpal spaces (“lesser arc”) or by fracturing associated carpal bones (“greater arc”).¹⁵ Graham subsequently described a third pattern, termed the “inferior arc” mechanism. In this mechanism, force is transmitted through the radiocarpal joint producing a fracture at the radial styloid or juxta-articular margin in addition to intercarpal injury.¹⁶ It was also suggested that this mechanism carries a high incidence of ulnar-sided pathology (e.g. TFCC tear, ulnar styloid fracture) as the force terminates on the medial aspect of the carpus. Herzberg later described the related perilunate instability non-dislocated (PLIND) injury, in which multiple combinations of ligamentous and bony injury may exist while the alignment of the carpus remains unchanged (i.e. capitate anatomically alignedt with the lunate).¹⁷

Consistent with these proposed mechanisms, ligamentous injuries are likely present in a considerable number of distal radius fractures whether or not they are identified on initial assessment. Several studies have independently confirmed high incidences of concomitant triangular fibrocartilage complex (TFCC), scapholunate interosseous ligament (SLIL), and lunotriquetral interosseous ligament (LTIL) injuries in both intra- and extraarticular fracture patterns. Many of these combined injuries are likely associated with mechanisms similar to those described by Tang, Mayfield, Graham, and Herzberg.

3 Incidence of concomitant soft-tissue trauma and sequalae of injury

With the development of high-resolution magnetic resonance techniques and use of arthroscopy, the true rate of soft tissue injuries occurring with distal radius fractures has been better elucidated. TFCC injuries comprise the most frequent group of soft tissue injuries associated with distal radius fractures. Numerous studies have sought to determine the true incidence of such lesions and estimate TFCC injuries occur in 39%–100% of fractures.^18–28 Different rates can in part be explained by how authors define injury, different diagnostic tools used, patient characteristics, and fracture types studied. Despite their reported prevalence, it is likely that only a subset of TFCC tears remain symptomatic and are of functional consequence. Nevertheless, patients with documented peripheral TFCC tears with their distal radius fractures have inferior outcomes at 1-year follow-up.²³

The incidence of concomitant intercarpal ligament injuries varies by study. SLIL rupture is estimated to occur in 16%–54% of distal radius fractures,^{10,17,18,24,25,28} while LTIL injury occurs less frequently in 8.5%–35% of cases.^{10,17,18,20,28} In one large retrospective review of 839 patients with distal radius fractures, 13% had persistent scapholunate dissociation following reduction of their fracture.²⁷ In another study, abnormal SL angles were present in 39% of patients with distal radius fractures at presentation and 35% after fracture treatment.²⁹ Both studies concluded that a majority of patients with an abnormal SL relationship at the time of injury will progress to static carpal instability and resultant arthritis if left untreated.

4 The challenge of discerning clinically significant lesions

Distal radius fractures with combined carpal or ligamentous pathology may be easily overlooked following acute injury, especially in the context of more readily identifiable fractures. Such patients will often present with a grossly edematous wrist and diffuse carpal tenderness.^17,30 Overall, the examination in the acute period after injury provides little specificity with regard to ligamentous pathology, especially in the setting of an obvious fracture.

Plain radiographs (PA, lateral, tilt lateral, oblique) are obtained in all patients with a suspected wrist injury. Displaced fractures of the distal radius and carpus should be easily identified, however more subtle trans-styloid, transcarpal, and juxta-articular fractures may be overlooked. Perilunate dislocation (PLD) or fracture-dislocation (PLFD) will be readily apparent when the lunate and capitate are grossly malaligned. However, in several variant patterns of PLD and PLFD, the lunate either never dislocates or spontaneously reduces prior to imaging.¹⁷ An x-ray is a static image of the wrist at a moment in time and may underestimate the degree of soft tissue injury that may have been imparted by the trauma. The only radiographic indication of a complex ligamentous injury may be the presence of osteochondral “chip” fractures, which might inappropriately be regarded as minor bony trauma. Such findings, as well as evidence of asymmetric scapholunate or lunotriquetral widening, abnormal sagittal carpal relationships, or DRUJ subluxation should prompt further evaluation.

In the setting of high energy trauma, the extent of carpal injury is often better characterized with advanced imaging. There is currently no consensus regarding the role of computed tomography (CT) scan for the preoperative assessment of distal radius fractures. While a systematic evaluation of plain radiographs accounts for most fracture patterns,³¹ CT scans can be useful for classifying and planning fixation in comminuted intra-articular fractures.³² Coronal CT scan images have been shown to be superior at diagnosing arthroscopically confirmed SLIL injury when compared to plain radiography. Additionally, there was better interobserver reliability with CT assessment.³³ Multidetector CT arthrogram has also been shown to have a high degree of sensitivity for detection of SLIL and LTIL injury, especially for discerning partial tears that may not require surgical intervention.^34,35

Magnetic resonance imaging (MRI) is not routinely obtained for acute distal radius fractures and instead is obtained after the persistence of pain following bony union. Most studies evaluating the role of early MRI for distal radius fractures focus on identification of concomitant TFCC and SL injury. In one study of 58 operatively managed distal radius fractures, 100% of patients had evidence of TFCC injury on preoperative 3T MRI.²³ With high fidelity MR screening, the challenge becomes not identifying soft-tissue lesions present with a fracture but distinguishing clinically relevant ones from those that will adequately heal during the period of fracture immobilization. When critical ligament insufficiency or rupture is suspected, wrist arthroscopy remains the gold-standard for confirming these injuries. This technique not only provides direct visualization of the ligaments, but also allows a method for treatment.

5 Principles for arthroscopic evaluation of distal radius fractures

Arthroscopic equipment should be requested and setup to avoid intraoperative delays. Much like the treatment of distal radius fractures in general, each pattern of injury should be individually assessed and managed. The decision to proceed with open vs. arthroscopic treatment can be made based on intraoperative findings and surgeon preference. The following provides an overview of arthroscopic distal radius fracture management which has been previously described.^3,49–52

In brief, the patient is brought to the operating room and placed supine on the operating room table. All bony prominences are well-padded, and a non-sterile tourniquet is placed on operative extremity, which is prepped and draped in sterile manner. Prior to addressing the injured extremity, we routinely examine the stability of the uninjured DRUJ, noting any laxity of the DRUJ in neutral, protonation and supination. Attention is then diverted to the operative extremity, which is elevated and exsanguinated, and the tourniquet insufflated.

An extended FCR incision is designed. After the skin is incised, blunt dissection is used to develop full-thickness skin flaps. The volar FCR tendon sheath is identified and incised longitudinally. The FCR tendon is retracted ulnarly and the dorsal FCR tendon sheath incised with care taken to find and protect the palmar cutaneous branch of the median nerve. The thick septum between the FCR and the FPL is then released after which the pronator quadratus is raised as an ulnarly based flap. The EPB and APL tendons are identified radially and the brachioradialis tendon is released. Callus formation and hematoma are debrided from the fracture site. We then attempt to get the best fracture reduction possible under fluoroscopic control, and provisional K-wire pins are placed either through or outside a volar locking distal radius plate. A nonlocking screw is placed centrally within the proximal part of the plate. The wrist is then placed in a well-padded arthroscopy tower with approximately 5–7 pounds of longitudinal traction.

The 6R portal is made first and acts as the initial viewing portal with the arthroscope. The 3–4 portal is made next, and an arthroscopic washout procedure is performed to confirm the extent of the injury and the articular reduction. If the reduction is acceptable, distal screw fixation is performed followed by proximal screw fixation. If there is evidence of articular incongruity, the distal K wires are withdrawn and the fracture fragments reduced, starting from the lunate facet followed by the scaphoid facet, respectively, using a combination of arthroscopic probe, manual or K-wire fragment manipulation. We routinely interchange the viewing and working portals to ensure the reduction can be confirmed from multiple angles. Once the articular surface is appropriately reduced, the arm is removed from the traction tower and standard distal and proximal screw fixation is performed.

Following distal radius fixation, the DRUJ is examined and compared to the contralateral side. If there is instability of the DRUJ, assuming we have anatomic restoration of the distal radius fracture, we will evaluate the TFCC using a combination of the hook, trampoline and suction tests. Arthroscopic assisted foveal repair of the TFCC or fixation of the ulnar styloid fracture, if applicable, is then performed. Midcarpal joint arthroscopy is performed if clinically or radiographically indicated based on the fracture pattern.

6 Case example

A 22-year-old manual laborer sustained an injury secondary to a fall onto his outstretched left wrist. Initial radiographs demonstrated a comminuted fracture of the left distal radius with a volar rim injury, a marginal dorsal triquetral fracture, and an ulnar styloid tip fracture (Fig. 1). CT scan of the left wrist better characterized the injury, demonstrating articular impaction, two coronal fractures involving the volar and dorsal margins, and scapholunate interval widening not well-appreciated on plain radiography (Fig. 2). Given these findings, a perilunate type mechanism was suspected.

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Fig. 1 (a) Oblique and (b) lateral radiographs demonstrating a comminuted, juxta-articular distal radius and ulnar styloid tip fracture.

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Fig. 2 Computed tomography (CT) scan of the patient's wrist. (a) Coronal plane imaging demonstrates a radial styloid fragment with articular impaction. (b) Sagittal plane imaging demonstrates a fracture involving the volar and dorsal margins of the radiocarpal articulation. (c) Axial plane imaging shows corresponding coronal split fractures at the level of the sigmoid notch.

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In the operating room, the fractures were manually reduced and percutaneous joystick pinning of styloid and dorsal wall fragments was performed. The upper extremity was then placed in an arthroscopy tower and as detailed above, 6R and 3-4 radiocarpal portals were developed. A 2 mm flexible arthroscope (NanoScope, Arthrex, Naples, FL, USA) was passed through the 6R portal and initial washout and debridement was performed using a shaver in the 3–4 portal to delineate the extent of the articular injury (Fig. 3). Under direct arthroscopic vision, the radiocarpal articular surface was reduced by manipulating the K wires and these were then advanced to secure fracture fixation (Fig. 4).

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Fig. 3 Following provisional reduction under fluoroscopic control, articular gapping is better appreciated by arthroscopic visualization.

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Fig. 4 Pins are withdrawn and manipulated to improve the articular reduction under direct arthroscopic visualization.

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Midcarpal arthroscopy was then performed. A Geissler 3 injury of the scapholunate interval with step off and a Geissler 2 injury of the lunotriquetral interval was also appreciated with avulsion of the dorsal capsule from the triquetral body. The wrist was then flexed to bring the lunate into a neutral position and a radiolunate pin was placed. Under arthroscopic visualization, the scapholunate and lunotriquetral intervals were reduced and stabilized using 0.045 in K-wires. A scaphocapitate pin was placed for additional stability. The dorsal capsule was then repaired back down to the triquetrum. To add stability to the construct, a dorsal spanning plate was placed in standard fashion to span the index metacarpal to the radial diaphysis (Fig. 5). This was removed after 8 weeks. The patient was able to work without restriction 6 months following his injury. At a final follow up of 14 months (Fig. 6), the patient demonstrated a 150° arc of pronosupination, 40° palmar flexion, 45° dorsiflexion, and 20° of radial and ulnar deviation, respectively. Grip strength was 94% of the uninjured side.

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Fig. 5 Final reduction (a) anteroposterior and (b) lateral radiographs demonstrate K-wire and dorsal spanning plate construct.

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Fig. 6 Left wrist (a) anteroposterior and (b) lateral radiographs demonstrating fracture union.

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7 Conclusions

Ligamentous injuries frequently occur with distal radius fractures and may be overlooked. A number of these injuries, if untreated, may progress to instability and subsequent wrist dysfunction. While improvements in imaging techniques have allowed for greater identification of these lesions, understanding the mechanism of injury and their propensity for associated soft tissue injuries is critical for the treating surgeon. Arthroscopic evaluation of such fracture patterns not only allows for improved articular reduction, but also allows treatment of the associated soft injuries when clinically indicated.

Funding/sponsorship

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Informed consent

Informed consent was obtained for the use of all clinical descriptions and radiographic images depicted in this manuscript.

Institutional ethical committee approval

No approval was required for this review article.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Contributions

CSC – Concept design and manuscript drafting. SK – Concept design and manuscript drafting.