19 Transscaphoid Perilunate Fracture Dislocations
▪ Anatomy and Pathomechanics
Although rare events, transscaphoid perilunate fracture dislocations (TSPLFDs) account for more than 60% of perilunate dislocations.1 Recognition of these debilitating perilunar injuries is often difficult and if left untreated can lead to extremely poor radiographic and functional outcomes.2 Cadaver work by Mayfield and colleagues defined characteristic patterns of progressive perilunate instability when the wrist was subjected to loads in extension, ulnar deviation, and intercarpal supination. Within their described spectrum of pathology, first the scapholunate interosseous ligament (SLIL) becomes disrupted, which is followed next by the lunocapitate interval, the lunotriquetral interosseous ligament (LTIL), and finally the fourth stage of radiolunate injury (via the dorsal radiocarpal ligament and/or the short and long radiolunate ligaments) occurs leading to either a perilunate or a true lunate dislocation3 ( Fig. 19.1 ). Although this purely ligamentous cascade illustrates a lesser arc injury to the carpus, the energy may also pass through any bone found within the greater arc of the wrist and cause fractures of the scaphoid, capitate, triquetrum, and radial and/or ulnar styloid ( Fig. 19.2 ).
▪ Diagnosis
TSPLFDs usually occur in young males in their twenties and thirties as a result of a high-energy trauma such as a fall from height or a motor vehicle accident.4 The affected wrist is typically deformed, swollen, and painful, and assessment of the extremity should begin with careful inspection to rule out an open injury. A thorough vascular and neurological examination is then performed, especially because median nerve symptoms can result either from nerve contusion or from increased carpal pressures secondary to soft tissue edema and hematoma formation. Almost one third of patients in some reported series display paresthesias in the median nerve distribution, and while the majority of these cases represent an acute nerve contusion and not an acute carpal tunnel syndrome, those patients with delayed onset of symptoms or a progressively worsening physical examination should undergo immediate open carpal tunnel decompression.5
Posteroanterior (PA) and lateral plain radiographs are usually sufficient to make the definitive diagnosis of perilunate fracture dislocation. The articular surfaces of both the proximal and distal carpal rows on a normal PA radiograph should form a series of three concentric and smooth arced lines, described by Gilula6 ( Fig. 19.3 ). Disruption of any of these lines suggests carpal instability or injury or both. Traction views may be helpful in some cases, and computed tomography (CT) is rarely necessary but can aid in identification of other more occult osteochondral fractures that are seen in the spectrum of greater arc pathology. The determination of the precise injury pathway is of significant importance to ensure that each individual component of the perilunar pattern is addressed ( Fig. 19.4 ). Again, diagnosis of perilunate injuries may be subtle; upward of 25% are missed initially in some reports.7
▪ Indications
Acute Injury
Once a transscaphoid perilunate fracture dislocation is recognized, the very first priority in treatment is to reduce the dislocation as quickly as possible to help prevent the potential risk of median nerve injury as well as optimize carpal alignment. Although the definitive treatment of these injuries is operative, the patient must first be hemodynamically stabilized because any life- or limb-threatening event takes precedence. Significant soft tissue swelling may necessitate a short delay in definitive internal fixation and repair, granted the dislocation is adequately reduced and there is no associated acute carpal tunnel syndrome. An attempt at closed reduction of the dislocation is typically made in the emergency department setting. Our common practice is to hang the wrist in traction with 10 to 15 lb for ∼5 minutes. Because the majority of these injuries are dorsal in direction, the reduction maneuver first consists of wrist hyperextension, which is then followed by counterpressure maintained at the level of the lunate volarly as the wrist is flexed to reduce the capitate into the lunate fossa.
Closed reduction often achieves gross realignment of the wrist, but accurate reduction of the small irregular carpal articulations requires open surgery. In the specific case of transscaphoid perilunate fracture dislocations, there are two main issues that must be addressed. First, the displaced scaphoid fracture must be rigidly fixed to help prevent the potential sequelae of avascular necrosis and nonunion. The second issue involves the restoration of carpal stability, which in some cases can be largely achieved with operative fixation of the scaphoid alone, but often requires further attention to the lunotriquetral interval with either ligamentous repair or reconstruction to prevent a volar intercalated segment instability (VISI) pattern of the carpus.
Delayed Presentation
Because upward of 25% of perilunate injuries are missed acutely, patients with unreduced perilunate dislocations may present weeks and even years following the initial injury.7 The delayed clinical presentation of transscaphoid perilunate fracture dislocations can range greatly from minimal symptoms to significant pain, weakness, and stiff-ness as the result of either posttraumatic carpal arthrosis, carpal tunnel syndrome, or even attritional flexor tendon disruption. Large series have documented that patients left untreated for an average of 22 years have the worst clinical scores of any cohort.1 Thus this dismal natural history suggests that surgical treatment should be considered regardless of the time that has lapsed since the original injury. Some debate exists as to the preferred method of surgical treatment in these more delayed presentations, including lunate excision, wrist arthrodesis, and proximal row carpectomy. Although most authors would agree that the procedure of choice for TSPLFD is open reduction internal fixation (ORIF), preferably within 6 weeks of injury, one study has shown successful results with ORIF as far out as 6 months.8
▪ Contraindications
There are few contraindications to ORIF, but an unreducible chronic lunate dislocation may require treatment with a proximal row carpectomy (PRC), which solves the twin problem of carpal degenerative change and a fixed wrist contracture. A nonreconstructable scaphoid would require either a PRC or a some type of partial wrist fusion. Avascular necrosis (AVN) of the lunate is another contraindication, though transient increased density of the lunate is not uncommon and does not necessarily mean AVN.
▪ Surgical Technique
Instrumentation/Operating Room Setup
Equipment required includes a hand table, tourniquet, fluoroscopy unit, 0.045-in. to 0.062-in. double-ended Kirschner wires (K-wires), wire driver, traction setup, headless cannulated compression screw system such as the Acutrak Screw set (Acumed, Hillsboro, OR) or the AO/ASIF screw set (Synthes, Paoli, PA), and mini–bone suture anchors.
▪ Surgical Approach and Dissection
It is our preference to use a dorsal approach with screw fixation of the scaphoid in all cases. A volar incision is made only on those patients requiring a simultaneous carpal tunnel release. Although not reported in our series, a volar approach for a transscaphoid perilunate fracture dislocation may be necessary in the event that the proximal pole of the scaphoid and/or the lunate becomes buttonholed through the volar wrist capsule.2
A longitudinal incision is made over the dorsum of the wrist just ulnar to the Lister tubercle. Care is taken to protect any cutaneous nerve branches. The extensor pollicis longus tendon is released from the third dorsal compartment and retracted radially along with the extensor radialis longus and brevis tendons. At this point we routinely isolate the posterior interosseous nerve (PIN) and artery at the floor of the third compartment. Because the PIN provides only sensory input to the dorsal wrist capsule at this level, we transect it proximally to prevent neuroma formation, and we coagulate the neighboring artery to prevent postoperative hematoma. Another vertical incision is then made in the capsule to expose the scaphoid.
Scaphoid Stabilization
The scaphoid is reduced and held with a 0.045-in. K-wire parallel to the eventual path of the compression screw. Occasionally, 0.062-in. K-wires (also placed away from the screw path) may be needed as joysticks to aid in fracture reduction. Utilizing a cannulated compression screw system, under fluoroscopy a guide wire is placed along the central scaphoid axis with the wrist flexed and forearm pronated to assess the long axis of the scaphoid. This will cause the outline of the scaphoid to appear as a dense circle in the PA view, and the guide wire is then driven in a dorsal to volar direction along that circle and in a proximal/ulnar to distal/radial direction in line with the first metacarpal ray until the distal cortex of the scaphoid is reached. PA and lateral fluoroscopic projections are then checked to verify placement of the guide wire down the central axis of the reduced scaphoid. Use of a second guide wire or depth gauge from the implant system allows measurement of scaphoid length, and we recommend subtracting 4 mm to account for fracture compression and clearance of the screw at each end to avoid penetrating the cartilage and thus violating an articular surface. Once the appropriate measurement is achieved, advance the central axis guide wire past the distal cortex of the scaphoid and into the trapezium. This is done to help ensure the guide wire is not removed during drilling. Maintain the wrist in flexion throughout the guide wire insertion, drilling, and placement of the screw to avoid bending the wire and potentially breaking it, especially if drilling on power ( Fig. 19.5 ). If the fracture shows significant comminution, bone graft can be obtained from the distal radius through the same dorsal incision.
Related posts:
7 Nonoperative Treatment of Scaphoid Fractures
8 Palmar Matti-Russe Graft
9 Scaphoid Waist Fracture: Open Reduction Internal Fixation via the Dorsal Approach
10 Scaphoid Nonunion: Open Reduction and Dorsal Bone Grafting
21 Scaphoid Fractures in Athletes
18 Arthroscopic Bone Grafting in Scaphoid Nonunion and Delayed Union
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