9 Scaphoid Waist Fracture: Open Reduction Internal Fixation via the Dorsal Approach
▪ Rationale for the Procedure
Nonoperative management has traditionally been advocated as the preferred treatment for a nondisplaced scaphoid waist fracture with excellent healing rates.1 – 3 The morbidity of cast immobilization, however, has become of increasing concern. A prolonged period of wrist immobilization is typically required and can result in muscle atrophy, stiffness, reduced grip strength, and residual pain.4 , 5 In addition, cast immobilization is inconvenient and interferes with the patient’s activities of daily living. Also, immediate internal fixation can be more cost effective when compared with nonoperative management.6 Thus there has been increasing interest in operative stabilization of nondisplaced scaphoid waist fractures.7 – 9
Various surgical approaches have been described for fixation of an acute nondisplaced scaphoid waist fracture. Screw insertion via a volar approach was first popularized by Herbert.10 It may be difficult, however, to gain access to the central axis of the scaphoid through a volar approach, which is important both biomechanically (because a screw that is inserted down the central axis demonstrates greater stiffness and a greater load to failure) and clinically, with a more rapid progression to healing.11 , 12 The dorsal approach is technically easier, and it affords more accurate and reliable screw insertion down the central axis of the scaphoid.13 We prefer the dorsal approach using a headless compression screw for fixation of nondisplaced and displaced fractures of the waist region.14 , 15
The technique is used in those patients with a nondisplaced scaphoid waist fracture who wish to proceed with operative treatment following an explanation and discussion of the rationale for, risks and benefits of, operative treatment versus cast immobilization. All displaced fractures require operative treatment. Other indications include a transscaphoid perilunate fracture-dislocation, concomitant distal radius fracture, or delayed presentation (>3 weeks) of a nondisplaced fracture with no prior treatment. There is no specific age limit, but good bone quality is essential to avoid screw failure. The sooner operative fixation is performed, particularly for a displaced fracture, the better.
Significant osteopenia with poor bone quality
▪ Surgical Technique
We prefer to use the Acutrak headless cannulated screw system (Acumed, Beaverton, OR). A general or regional anesthetic may be used. The patient is positioned supine on the operating table with a radiolucent hand table. A pneumatic tourniquet is applied on the proximal arm. Following prep-ping and draping of the limb, exsanguination is performed with an Esmarch bandage with inflation of the tourniquet to a pressure of 250 mm Hg. The forearm is pronated and a longitudinal skin incision ∼2 cm in length is placed beginning at the proximal aspect of the Lister tubercle extending along the axis of the third metacarpal ( Fig. 9.1 ). Full-thickness skin flaps are raised and the extensor retinaculum of the third compartment is incised immediately distal to the Lister tubercle, releasing the extensor pollicis longus (EPL) tendon. The extensor digitorum communis (EDC) tendons are gently retracted ulnarly while the extensor carpi radialis brevis (ECRB) and longus (ECRL) tendons are retracted radially with the EPL to expose the underlying joint capsule ( Fig. 9.2 ). A limited inverted T-shaped capsulotomy is made with the transverse limb placed just distal to the dorsal rim of the radius and the longitudinal limb directly over the scapholunate articulation ( Fig. 9.3 ). The capsular flaps are carefully elevated from the dorsal lunate, the dorsal component of the scapholunate (SL) ligament, and the proximal pole of the scaphoid. Care is taken to avoid damaging the dorsal component of the SL ligament and the nutrient branches from the radial artery entering the dorsal scaphoid ridge.
▪ Nondisplaced Fracture
The wrist is flexed and the proximal pole and scapholunate ligament are identified. The guide wire is inserted at the membranous portion of the scapholunate ligament and is aimed down the central axis of the scaphoid toward the thumb perpendicular to the fracture if possible ( Fig. 9.4 ). The exact insertion point is dictated by the fracture location and orientation. A mini-Acutrak screw may be necessary in those patients with a small scaphoid, a small proximal pole fragment, or a fracture that extends proximally such that insertion of a larger standard Acutrak screw may result in fragmentation of the proximal scaphoid. Fluoroscopy is used to confirm correct wire placement ( Fig. 9.5 ). A lateral view of the wrist is obtained but it can be difficult to visualize the central axis. We have found a 30 degree pronated lateral view and dynamic imaging during forearm pronosupination to be more helpful. A posteroanterior (PA) view with the wrist held in slight palmar flexion and ulnar deviation is also obtained, with care taken to avoid bending the guide wire. The wire is advanced up to but not into the scaphotrapezial joint, and the screw length is then determined ( Fig. 9.6 ).
We prefer to subtract 4 mm from the measured length to allow recession of the proximal screw head beneath the articular surface. Once the screw length has been determined, the wire is driven into the trapezium to avoid a loss of position during reaming. If there is any concern about fracture stability, a derotational 0.045 K-wire is inserted dorsal and ulnar to the guide wire. The cannulated reamer is then used with power followed by manual insertion of the screw ( Fig. 9.7 ). The guide wire is removed and the screw position is assessed via fluoroscopy ( Fig. 9.8 ).