Thumb function constitutes about 50% of hand function as a whole. The thumb metacarpal base is a unique joint that allows a wide range of motion while maintaining stability for grasp and pinch in a variety of positions.
Multiple fracture patterns of the thumb base have been described, including juxta-articular metaphyseal fracture, Bennett fracture, and Rolando fracture. Interest in the fixation of these fractures has been stimulated by the marked decrease in hand function that can develop in the affected patients if disabling arthritis occurs in the thumb carpometacarpal (CMC) articulation as a result of articular incongruity following such fractures.[1, 2, 3, 4, 5]
Rolando fracture initially was described in 1910 in a series of 12 metacarpal base fractures, of which three involved a Y-shaped split of the joint surface.[6, 7] The fracture was described as having the following three major fragments:
Since the original description, the term Rolando fracture has come to include essentially all comminuted thumb metacarpal base fractures.[8]
Generally, significant joint incongruity (ie, >1-2 mm of articular stepoff) mandates treatment; however, the type of treatment can vary and has been somewhat controversial. The treatment options initially described focused mainly on closed treatment: either cast immobilization or a short period of splinting followed by early motion to mold joint surfaces. With the advent of internal fixation techniques, especially smaller implants, interest in operative treatment increased over subsequent decades.[9, 10]
For additional information on related fractures, see Metacarpal Fractures, Thumb Fractures and Dislocations, Thumb Dislocation Joint Reduction, Metacarpal Fractures and Dislocations, and Bennett Fracture.
The CMC joint surface consists of two reciprocal interlocked saddles that allow motion parallel and perpendicular to the plane of the palm. Compressive forces across the joint appear to be magnified during pinch and have been estimated at 12 times the pinch force.[11] Articular incongruity, therefore, is subjected to high forces and increases the likelihood of arthrosis development. As a result, there has been considerable interest in finding ways to improve the accuracy and security of reduction techniques.
After this kind of injury, the fracture is at risk for further displacement because of the resting tone present in the multiple tendons that act on the thumb. The extensor pollicis brevis (EPB) and the extensor pollicis longus (EPL) shorten the thumb ray, as does the pull of the flexor pollicis longus (FPL). The adductor pollicis tends to pull the distal metacarpal toward the palm, which, in conjunction with the abductor pollicis longus (APL) acting on the metacarpal base, commonly produces varus at the metaphyseal-diaphyseal junction.
Rolando fracture is analogous to the pilon fracture of the distal tibia and appears to be secondary to a significant axial load that splits and crushes the metacarpal articular surface. Rolando described two cases that occurred secondary to a fall on the radial side of the hand, with the thumb in adduction, and a third case that was caused by a closed fist, with the thumb folded and held in the palm, striking an adversary's head.[6, 12]
Langhoff et al studied 16 patients who underwent open reduction with fine Kirschner wires (K-wires).[13] At a mean follow-up of 5.8 years, nine patients had no residual symptoms, six had symptoms with moderate activity, and one had significant symptoms necessitating a change in occupation. Eight had reduced range of motion (ROM), and three had a visible deformity of the thenar base region that was related to large residual angulations of 35-55ยบ. Osteoarthritic changes were present in six (55%) of the 11 patients with radiographs at follow-up; this did not appear to correlate with the quality of reduction or with late symptoms.
Proubasta reported the results of five patients treated with a mini external fixator.[14] Pins were placed in the trapezium and thumb metacarpal shaft, and the fracture was reduced with distraction. At short-term follow-up at 3 months, no complications were noted, and the patients all were free from pain and had a full range of thumb movements.
Buchler et al described the management of 13 complex thumb metacarpal base fractures in which multiple fragments were involved.[15] The authors treated the fractures with external fixation between the index and thumb metacarpals and limited internal fixation of the joint surface using pins, screws, or both. They performed bone grafting of the metaphyseal void present after distraction. At follow-up (average, 35 mo), there were no significant complications and no loss of reduction, malalignment, or secondary subluxation. Grip and pinch strength were 81% and 88% of the contralateral side, respectively. Rotation of the thumb metacarpal was 79% of the unaffected side. No diffuse degenerative changes occurred.
Following injury, patients present with a swollen, tender thumb base. If significant varus has developed, a clinically visible deformity may be present. However, swelling can mask a surprising amount of angulation. Neurovascular and tendon injuries are not commonly associated with this fracture.
Anteroposterior (AP) and lateral radiographs of the thumb often do not reveal the full extent of articular comminution (see the image below)
Additional radiographic views include a Robert radiograph (a hyperpronated view of the thumb base), tomography, and computed tomography (CT). (See the images below.)
Improved assessment of the number of fragments and metaphyseal impaction can aid in decision-making with regard to open reduction versus external fixation.
Significant joint incongruity (ie, >1-2 mm of articular stepoff) mandates treatment. However, the type of treatment can vary and is somewhat controversial.
Large articular fragments in which screws can be used are probably best supported by plate-and-screw fixation, whereas massive comminution is best treated with a form of traction. Open fractures require debridement, and operative stabilization is recommended to stabilize the skeleton and allow soft-tissue healing. Pin fixation or external fixation is preferred in the presence of open injuries to minimize soft-tissue stripping.[16]
Contraindications for surgery are few; a systemically ill patient following polytrauma who cannot undergo any surgical procedure is an example of a patient in whom surgery would be contraindicated. An open fracture that has large fragments (normally treated with plate-and-screw fixation) and is massively contaminated would best be managed with traction and repeated debridements.
Additional research will help identify fractures that safely can be managed with internal fixation alone, as well as help differentiate these injuries from the more severely comminuted fractures that need external fixation for ligamentotaxis and protection of the fracture.
If open reduction is thought to be a reasonable choice for the patient with a Rolando fracture, a curvilinear incision is made at the thumb base. Branches of the superficial radial nerve dorsally and the lateral antebrachial cutaneous nerve volarly are identified with loupe magnification, isolated, and protected.
The periosteum is split along the first metacarpal shaft, and the joint is entered in the interval between the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons. Large articular fragments are identified. The articular surface is reconstructed in a piecemeal fashion with fine Kirschner wires (K-wires) and then secured to the metacarpal shaft by using a small T plate (see the image below). Intraoperative radiographs are obtained to confirm a satisfactory reduction, and the limb is placed in a thumb spica splint.
Comminuted metacarpal base fractures that cannot be secured with pins or screws can be treated with external fixation.[16, 17, 18, 19, 20, 21] One technique involves a quadrilateral frame with two pins each in the thumb and index metacarpals, limited K-wire fixation of the articular surface, and bone grafting of any metaphyseal void that has been created after length restoration. Another technique involves placing fixator pins in the trapezium and metacarpal shaft to maintain distraction.
Byrne et al recommended dynamic "S"-Quattro (Stockport Serpentine Spring System) as a primary and definitive treatment modality for external fixation of complex fractures of the base of the thumb when conservative and other surgical interventions have failed.[17]
Spangberg and Thoren described the use of oblique K-wire traction in the treatment of Bennett fracture.[22] Gelberman expanded this to include comminuted metacarpal base fractures and trapezial fractures.[23] The technique involves use of a single K-wire that is passed from the metacarpal base out of the thumb web, with a small hook on the proximal end of the wire. The distal end is then attached to an outrigger through rubber bands. Active motion is started to mold the joint surface. This traction neutralizes displacing muscle forces and maintains reduction through ligamentotaxis.
Wang et al (N = 40) evaluated the clinical efficacy of closed reduction and percutaneous parallel K-wire interlocking fixation between the first and second metacarpals (n = 20) as compared with traditional fixation (N = 20) for treatment of first metacarpal base fractures.[24] The modified fixation technique was associated with shorter operating times, lower postoperative visual analogue scale (VAS) pain score, and better effective range of motion in the first carpometacarpal (CMC) joint
Complications are often directly related to the extent of the comminution. Hardware-related issues can develop, such as pin-tract infection or screw pullout with resultant loss of fixation. Soft-tissue complications include damage to the branches of the superficial radial or lateral antebrachial cutaneous nerve. Some degree of joint stiffness is inevitable, given the articular nature of the fracture.
Secure plate fixation can allow early motion of the joint surface. However, if the comminution requires grafting and stability is a concern, immobilization in a thumb spica cast for 4-6 weeks is the safest course of action. External fixators, K-wires, or both can be removed at approximately 6 weeks postoperatively, and active motion can begin.