Evidence Behind the Non-Operative Management of Metacarpal Fractures
Introduction. Metacarpal fractures are a commonly encountered orthopedic injury. Metacarpal fractures can occur at the head, neck, shaft, or base of the metacarpal. When evaluating fractures of the metacarpals, knowledge of the surrounding musculature is required. The dorsal and palmar interosseous muscles originate from the metacarpals (Morcos, 2015). The role of the dorsal interosseous muscles is finger abduction and extension and the palmar interosseous muscles is finger adduction (Morcos, 2015). The metacarpals are also flanked by the extensor tendons, flexor tendons, and lumbricals (Victor Wong, 2017) . Each metacarpal is also supported by a volar plate ligament located on the palmar surface and these are connected by the deep transverse metacarpal ligaments (Victor Wong, 2017). Diagnosis is typically made with a three view xray. A study published in the American Journal of Emergency Medicine evaluated the use of ultrasound in the diagnosis of metacarpal fractures; they found a sensitivity of 92.5% and specificity of 98.28% (S. Kocaoglu, 2016). This data is especially useful to sideline physicians who may have portable ultrasound immediately available which can be used in lieu of radiographs. In this article, we will review the different fracture types and evidence behind treatment regiments.
Metacarpal head fractures. Metacarpal head fractures are less commonly seen than the other metacarpal fracture types (Thomas McNemar, 2003). The most commonly seen metacarpal head fracture is the second metacarpal due to its decreased mobility (EC McElfresh, 1983). These fractures are most commonly seen in sporting injuries and fights (EC McElfresh, 1983). Metacarpal head fractures typically involve the articular surface and those that involve less than 20% of the articular surface can be managed conservatively (Thomas McNemar, 2003). In order to preserve the MCP collateral length the fracture can be immobilized in a radial or ulnar gutter splint. McNemar did this by positioning the wrist in zero to 20 degrees of extension, the MCP joint in 90 degrees of flexion and the interphalangeal joints in extension (Thomas McNemar, 2003).
Avulsions of the metacarpal head may also occur from pulling of the collateral ligaments during an injury. In 2006 DJ Shewring looked at avulsion fractures of the metacarpal head and treated them with internal fixation or nonoperatively in a thermoplastic splint (DJ Shewring, 2006). What they found was that 11 patients received internal fixation immediately after the injury and all had united fracture by three months (DJ Shewring, 2006). The group treated conservatively included seven total patients. Four regained full motion by 6 weeks but three required internal fixation due to persistent pain (DJ Shewring, 2006). The authors found that those who went on to surgical fixation after a failed period of nonoperative treatment that the surgery was not more difficulty than those undergoing early surgery (DJ Shewring, 2006). This led them to conclude that for nondisplaced avulsion fractures at the metacarpal head a trial of nonoperative management should be attempted first to avoid the risks of surgery (DJ Shewring, 2006).
In a review done by McElfresh on intra-articular metacarpal head fractures, he found that transverse fractures of the metacarpal head had high rates of developing avascular necrosis (EC McElfresh, 1983). However, the most common fracture type of the metacarpal head is a comminuted metacarpal head fracture. Those fractures that are comminuted but show minimal displacement and little articular involvement can be managed with immobilization and then protected motion (EC McElfresh, 1983).
Metacarpal neck fractures. Metacarpal neck fractures of the fifth digit account for 20% of hand fractures (Lowdon, 1986). There is high variability among physicians when calculating the angle of displacement for a fifth digit metacarpal neck fracture. Lowdown found that depending on the projection used to measure the displacement angle a smaller or larger angle could be measured (Lowdon, 1986). He suggests that the difficulties in measuring the angle of displacement is the reason why we have studies proposing many different angles for what is acceptable displacement angle (Lowdon, 1986).
A study published in the Journal of Hand Surgery in 1998 looked at different splinting options for metacarpal neck fractures. They randomized patients in to groups with one group being treated with ulnar plaster-of paris cast, one group in a functional brace and one in an elastic bandage (PB Hansen, 1998). They then evaluated the patients for fracture tenderness at 4 weeks and 3 months (PB Hansen, 1998). What they found was that the functional brace performed as well as the plaster-of-Paris cast when measuring pain (PB Hansen, 1998). The patients in the elastic bandage did poorly, they had more pain and restrictions in motion (PB Hansen, 1998). At 3 months patients in the plaster and the functional brace had no differences in their range of motion (PB Hansen, 1998). Hansen’s study supports the use of a functional brace but against the use of an elastic bandage. Another study looking at immobilizing the fifth metacarpal fracture in extension or flexion done by Hofmeister found that there were no differences in range of motion or grip strength from either position (Shin, 2008). Finally, a Cochrane review in 2005 by Poolman found that in the treatment of closed fifth metacarpal neck fractures there was no immobilization method that was superior to others (Poolman, 2005).
Take home point: There is no advantage to splint a fracture of the metacarpal neck with the MCP in flexion or extension.
Metacarpal shaft fractures. There are three fracture patterns for metacarpal shaft fractures: transverse, spiral and comminuted (Scott Wolfe, 2017). Green’s Operative Hand Surgery proposed guidelines for the amount of angulation and shortening allowed when treating metacarpal shaft fractures. They recommend allowing transverse shaft fractures to have angulation up to 30 degrees in the fifth digit, 20 degrees in the fourth digit, and not allowing any angulation in second- and third-digit transverse fractures (Scott Wolfe, 2017). They also state that shortening of 2-5mm is tolerated (Scott Wolfe, 2017). Typically, the deep transverse metacarpal ligaments will prevent shortening (A Khan, 2015)
According to Burkhalter in 1989, the first test when evaluating whether to treat a metacarpal shaft fracture with internal fixation or with splinting is to evaluate the patients range of motion by having them open and close their hand completely (Burkhalter, 1989). The physician should evaluate for rotational deformities by having the patient make a fist to ensure that none of the fingers overlap (Burkhalter, 1989). If patient has near complete flexion and extension and no overlapping then he opted for a nonoperative treatment and placed patients in a short arm cast (Burkhalter, 1989).
A study published in the Journal of Hand Surgery in 2008 look at the role of splint immobilization for spiral/long oblique metacarpal shaft fractures (Al-Qattan, 2008). Previously it was thought that shortening of the metacarpal after a spiral/oblique fracture of 2-4 mm was an absolute indication for surgery (Al-Qattan, 2008). However, in a study by Eglesder in 1997 he found that in isolated spiral/long oblique fractures an intact deep transverse metacarpal ligament will stabilize the metacarpal and no further shortening will be seen (Eglseder, 1997). In the study done by Al-Qattan he placed any minimally displaced fracture with no angulation or rotational abnormality in a volar wrist splint with immediate finger mobilization and if there was significant angulation a short arm cast or gutter splint (Al-Qattan, 2008). Only those fractures that were severely displaced or had significant rotational deformity were managed surgically (Al-Qattan, 2008). What he found was that the groups treated with splints all had healing at 6 weeks and resolution of an extension lag at 6 months (Al-Qattan, 2008).
Early research supported placing the hand in the intrinsic plus hand position to prevent collateral shortening (Tavassoli, 2005). Tavassoli in 2005 aimed to evaluate three different casting positions for metacarpal shaft fractures. The first group flexed the MCP joint and allowed full IP motion, the second group extended the MCP joint and allowed full IP joint motion, and the third group placed the hand in the intrinsic plus position with flexed MCP joint and immobilizes IP joint in extension (Tavassoli, 2005). What he found was that regardless of cast type fracture alignment was preserved, no difference in grip strength, and no difference in range of motion. His study provides evidence against the need to place the MCP joint in flexion (Tavassoli, 2005).
Take home point: Isolated metacarpal fractures will heal well in a short arm cast or gutter splint if there is no rotational deformity.
Metacarpal base fractures. Fractures of the metacarpal base of digits two, three and four are rare and little evidence exists to guide management (Scott Wolfe, 2017). The more common fracture seen at the CMC joint is an intra-articular fracture of the hamate and fifth metacarpal joint (Scott Wolfe, 2017). It is seen by most as an unstable fracture and the evidence points to ORIF (Scott Wolfe, 2017). One of the key determinants when evaluating a metacarpal base fracture to see if it can be managed nonoperatively is to assess for carpometacarpal joint instability (Duretti Fufa, 2012). To better evaluate for instability a CT, lateral or oblique radiograph can help evaluate for carpometacarpal dislocation (Duretti Fufa, 2012).
Take home point: Evaluate for instability if a metacarpal base fracture is found.
Thumb metacarpal fractures. Fractures of the thumb metacarpal amount for 25% of all metacarpal fractures (Tiffany Kadow, 2016). The keys to treating thumb metacarpal fractures are similar to the treatment of the other metacarpals. However, due to the range of motion of the thumb the fractures can tolerate larger degrees of angulation (Duretti Fufa, 2012). It is estimated that they can tolerate up to 30 degrees of angulation (Victor Wong, 2017) The trapeziometacarpal joint can allow motion in flexion/extension, abduction/adduction, and pronation/supination (Tiffany Kadow, 2016). Overall, most extraarticular thumb metacarpal fractures are treated with immobilization in thumb spica (Tiffany Kadow, 2016).
There are two intra-articular fractures that the provider should be aware of. The Bennett fracture involves the metacarpal base and is an avulsion fracture of the volar-ulnar joint fragment (Duretti Fufa, 2012). The Rolando fracture is an intra-articular comminuted Y-shaped fracture located at the base of the metacarpal (Duretti Fufa, 2012). Both fractures require surgical fixation (Duretti Fufa, 2012).
Take home point: First metacarpal fractures can tolerate up to 30 degrees of angulation and should be treated with a thumb spica splint.
Conclusion. Metacarpal fractures are a common part of any orthopedic clinic. The purpose of this review was to evaluate the treatment of multiple different metacarpal fractures. Ultimately, the data is limited and shows that there are multiple positions that can lead to union of metacarpal fractures. Becoming familiar and comfortable with one casting technique is a necessary part of your orthopedic practice.