The dorsal approach to the treatment of complex metacarpophalangeal
joint dislocations of the fingers may offer the critical advantage of decreased
risk of neurovascular injury, as well as the ability to manage associated
Complex metacarpophalangeal (MP) joint dislocations were
classically described by Kaplan1 to involve rupture of the volar
plate from its weaker proximal attachment to the metacarpal. The volar plate
becomes entrapped between the metacarpal head and base of the proximal phalanx
by its attachment to the deep transverse metacarpal ligament, thus becoming the
primary impediment to reduction.2-6 The flexor tendons, pretendinous
band of the palmar fascia ulnarly, and lumbrical muscles radially may form a
noose around the dislocated MP joint, further inhibiting closed reduction.
Initial attempts at reduction using traction will further tighten this
envelope, possibly interposing additional structures. This underscores the need
for clinical and radiographic recognition of this injury pattern. The radial
digital nerve of the index finger is under tension and often assumes a
precarious position between the metacarpal head and the skin, making it
susceptible to injury during the volar approach (Figure 1).
Figure 1: Illustration of complex MP joint dislocation of the index finger.
On examination, the patient with a complex MP joint
dislocation will have a relatively benign clinical appearance consisting of
mild extension and ulnar deviation at the MP joint, as well as flexion of the
interphalangeal (IP) joints (Figure 2). A pathognomonic sign of palmar skin
puckering over the head of the metacarpal may be observed.1 The
posteroanterior (PA) plain radiograph demonstrates dorsal dislocation of the
phalangeal base ulnarly5-9 (Figure 3A), while the lateral radiograph
shows a dorsal dislocation with the MP joint in slight hyperextension (Figure
3B). The presence of sesamoid interposition within the MP joint, best
visualized on the oblique radiograph, is pathognomonic.7,9-11 Open
reduction is the treatment of choice for complex MP joint dislocations, as
closed reduction is contraindicated.
Metacarpophalangeal joints of the fingers are relatively
resistant to injury secondary to their strong capsuloligamentous structures and
their protected position at the base of the finger.12 The joint
capsule is supported palmarly by the volar plate, which has a thinner
attachment to the metacarpal and a thick fibrocartilaginous attachment to the
proximal phalanx. Laterally, the MP joint is reinforced by the deep transverse
metacarpal and collateral ligaments.13 The extrinsic and intrinsic
tendons as well as the sagittal bands lend secondary support.
|Figure 2: AP (A) and lateral (B) clinical views of complex MP joint dislocation.
Dorsal MP joint dislocations tend to occur most
frequently among the exposed border digits, with the index finger most commonly
affected, followed by the small finger.14,15 The long and ring
fingers are protected by the deep transverse metacarpal ligaments and the
border digits such that they rarely suffer an isolated
dislocation.16 Complex MP joint dislocations, by definition, require
open reduction. This may be accomplished via either a volar or dorsal approach.
Although some articles describe the dorsal approach,3,5,16 more
frequently cited in the literature is the volar
approach.1,2,4,6-8,11,17-24 This article reviews the operative
technique for open reduction of complex MP joint dislocations using a dorsal
approach with novel tips for reduction.
Materials and Methods
|Figure 3: PA (A) and lateral (B) radiographs of the index finger complex MP joint dislocation.
A 35-year-old right-hand-dominant construction worker
presented with pain, swelling, and tingling involving his left index finger
following a hyperextension injury. Clinical examination revealed the left index
finger MP joint was in slight extension and the IP joints were in mild flexion
with swelling. Palmar skin puckering over the metacarpal head was noted. A
volar prominence was palpated at the MP joint corresponding to the metacarpal
head with a void dorsally. Motor examination of the digit was intact.
Paresthesias of the entire finger and brisk capillary refill were recorded.
Radiographs demonstrated dorsal dislocation of the
proximal phalanx of the index finger without fracture. Multiple attempts at
reduction under anesthesia were unsuccessful. Given the clinical and
radiographic picture of a complex MP joint dislocation, no further attempts at
closed reduction were undertaken. After return to sobriety, we proceeded with
operative reduction via a dorsal approach.
An arm tourniquet is applied, and under regional
anesthesia the upper extremity is prepped and draped in the usual sterile
fashion. A curvilinear incision is made overlying the MP joint (Figure 4). The
ulnar sagittal band of the extensor mechanism is incised and later repaired.
The capsule is incised longitudinally and inspection of the joint is undertaken
(Figure 5). The collateral and accessory collateral ligaments may be imbricated
into the joint.
The volar plate is the most common impediment to
reduction and must be carefully assessed. Often, the volar plate remains
attached to the proximal phalanx and may become completely dorsally
translocated over the metacarpal head (Figure 6). Initially the volar plate may
be confused with the articular surface of the metacarpal head as it is taut,
shiny, and white, with an appearance similar to articular cartilage. Close
inspection and proper identification of anatomic structures is critical for
proper reduction of the MP joint. Manipulation of the volar plate with a Freer
Elevator may be attempted in an effort to reduce the joint maintaining the
continuity of the volar plate. More commonly, a longitudinal incision in the
volar plate (with articular protection afforded by a Freer Elevator passed over
the metacarpal head) will allow it to be reduced over the metacarpal head
(Figure 7). The leaflets of the volar plate are allowed to subluxate radial and
ulnar to the metacarpal head.
|Figure 4: Incision line for dorsal MP joint approach of index finger. Figure 5: Longitudinal capsular incision. Figure 6: Volar plate interposed within MP joint impeding closed reduction.
As the metacarpal head is being reduced, care must be
taken to identify any osteochondral fracture. This allows for a concentric,
stable reduction without injury to the articular surfaces. Direct visualization
and intraoperative fluoroscopic evaluation confirms a stable reduction through
a full arc of motion (Figure 8). The capsule is reapproximated with 4-0 Vicryl
(Ethicon, Somerville, New Jersey) while the extensor mechanism is reconstituted
with 4-0 Tycron (Covidien, Mansfield, Massachusetts) to prevent iatrogenic
subluxation. Skin is closed with nonabsorbable horizontal mattress sutures
after tourniquet deflation and hemostasis is confirmed.
The patient is then placed into a radial gutter splint
with the wrist in gentle extension, the MP joint in 70° to 90° of
flexion, and the IP joints in extension. Early protected mobilization with a
gutter-type splint is initiated after a few days to allow early wound healing.
Strengthening begins at 6 weeks to allow for ligamentous healing.
|Figure 7: Longitudinal split of volar plate. Figure 8: PA (A), lateral (B), and oblique (C) radiographs, postreduction.
At 6-week follow-up, the patient’s active range of
motion consisted of MP joint hyperextension to 5° and 70° of flexion,
proximal interphalangeal joint extension to 0° and flexion to 85°, and
distal interphalangeal joint extension to 0° and flexion to 70°. He had
32 lb of grip strength on the left compared to 65 lb on the right. Two-point
discrimination was within normal limits. Radiographs demonstrated maintenance
of reduction. Despite multiple telephone contacts with the patient, further
follow-up was unobtainable; but the patient assured us that he had returned to
Kaplan1 and other
authors2,4,6-8,11,17-24 described a volar approach to complex MP
joint dislocations. This approach requires an extensive release of volar
structures, including the volar plate, and places the radial digital nerve at
great risk.3,25 Other authors3,5,16 promoted the dorsal
approach due to the increased risk of digital nerve injury in the volar
approach. Becton et al3 reported a series of complex MP joint
dislocations of the index finger using both volar and dorsal approaches. All 9
patients who underwent a dorsal approach had normal function, while 2 of 3
patients in whom the volar approach was used had anesthesia of the radial
aspect of the index finger with limited MP joint range of motion.
The dorsal approach to complex dislocations of the MP
joint may offer several advantages over the volar approach. First, there is a
reduced risk of injury to the neurovascular bundle, which lies tented volarly
between the metacarpal head and skin.4,5,10 During the volar
approach, damage to the radial neurovascular structure has been well documented
in the literature.5,10 Furthermore, the management of associated
osteochondral fractures, which may be present in up to 50% of
cases,3,5 is facilitated by the dorsal approach. Lastly, the dorsal
approach allows full visualization of the primary impediment to reduction: the
volar plate. It is important to note that the volar plate often drapes dorsally
over the metacarpal head, possibly mimicking the articular surface of the
A potential disadvantage of dorsal open reduction is the
need to split the volar plate to reduce the metacarpal head. Theoretically,
splitting of the volar plate may delay recovery and reduce stability of the
healing MP joint. However, there are no published reports of this occurrence.
Our rehabilitation protocol ignores this longitudinal split of the volar plate,
concentrating on early range of motion.
The volar and dorsal approaches are viable options in
the treatment of complex MP joint dislocations of the fingers. The dorsal
approach may offer the critical advantage of decreased risk of neurovascular
injury, as well as the ability to manage associated osteochondral fractures.
Randomized clinical trials comparing the dorsal and volar approach are needed
to further assess their relative effectiveness in treating complex MP joint
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Drs Patterson, Maschke, Evans, and Lawton are from The
Cleveland Clinic, Cleveland, Ohio.
Drs Patterson, Maschke, Evans, and Lawton have no
relevant financial relationships to disclose.
Correspondence should be addressed to: Jeffrey N.
Lawton, MD, Department of Orthopedic Surgery, A40, Section of Hand & Upper
Extremity Surgery, The Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195.