Review Article

Metacarpophalangeal Joint Dislocation Abstract Paul Dinh, MD Adam Franklin, MD Brian Hutchinson, MD Stephen B. Schnall, MD Isabella Fassola, MD

Dr. Dinh is Hand Fellow, Department of Orthopaedic Surgery, Keck School of Medicine, LAC/USC Medical Center, Los Angeles, CA. Dr. Franklin is Resident, Department of Orthopaedic Surgery, Keck School of Medicine, LAC/USC Medical Center. Dr. Hutchinson is Hand Fellow, Department of Orthopaedic Surgery, Keck School of Medicine, LAC/USC Medical Center. Dr. Schnall is Professor, Clinical Orthopaedics and Surgery, Department of Orthopaedic Surgery, Keck School of Medicine, LAC/USC Medical Center. Dr. Fassola is Faculty Member, Department of Orthopaedic Surgery, Keck School of Medicine, LAC/USC Medical Center. None of the following authors or a member of their immediate families has received anything of value from or owns stock in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Dinh, Dr. Franklin, Dr. Hutchinson, Dr. Schnall, and Dr. Fassola. Reprint requests: Dr. Schnall, Keck School of Medicine, University of Southern California, 2025 Zonal Avenue, GNH 3900, 9312, Los Angeles, CA 90089. J Am Acad Orthop Surg 2009;17: 318-324 Copyright 2009 by the American Academy of Orthopaedic Surgeons.

318

Traumatic dislocation of the metacarpophalangeal joint is a relatively uncommon injury. The dislocation may be easily reducible (ie, simple) or require surgical intervention (ie, complex). The flexor tendons, lumbrical muscle, natatory ligament, and superficial transverse metacarpal ligament combine with the displaced volar plate to create a tight noose, preventing reduction. Surgical approach may be dorsal or volar; however, the radial digital nerve to the index finger is especially at risk through the volar approach. Reported complications include stiffness, arthritis, osteonecrosis of the metacarpal head, and even premature closure of the physis.

T

raumatic dislocation of the metacarpophalangeal (MCP) joint is considered a rare injury, although the experience of Hunt et al1 indicates that it might be an infrequently reported injury rather than one that rarely occurs. A dislocation is considered to be simple when it is easily reducible without open surgical procedures and complex when open reduction is necessary. Complex dislocation of the MCP joint was originally described by Farabeuf 2 in 1876. However, not until 1957 did we begin to develop a better understanding of the difference between simple and complex fractures. In that year, Kaplan3 published his now classic article describing the pathologic anatomy of the metacarpal head buttonholing into the palm and the factors preventing closed reduction.

Anatomy The complex shape of the metacarpal head, its articular surface, and supporting soft-tissue structures allow for multiplanar motion: flexion,

extension, abduction, adduction, and circumduction. The metacarpal head is asymmetric in the coronal and sagittal planes. The articular surfaces form a condyloid joint with a shallow and concave proximal phalanx congruent with the large metacarpal head. The total range of motion (ROM) of the MCP joint is greater than that of the proximal and distal interphalangeal joints.4 The capsule of the MCP joint extends from the metacarpal neck to the base of the proximal phalanx and is reinforced by ligamentous structures on all sides. The proper collateral ligaments are the primary stabilizers of the MCP joint throughout its ROM.5 These ligaments originate from depressions on both sides of the metacarpal head dorsal to its axis of rotation and extend distally in an oblique direction, from dorsal proximal to volar distal, rather than truly parallel to the joint. Their insertions are at the base of the proximal phalanx. This unique arrangement makes the proper collateral ligaments tauter in flexion than in extension. The accessory collateral ligaments originate volar to the proper

Journal of the American Academy of Orthopaedic Surgeons

Paul Dinh, MD, et al

collateral ligaments and insert onto the volar plate. Because of their volar origin, the accessory collateral ligaments are relatively taut in extension and lax in flexion. The volar plate stabilizes and supports the MCP joint on the palmar aspect. This plate has a thick fibrocartilaginous portion distally and a looser, membranous portion proximally. This anatomic difference allows for some hyperextension of the MCP joint. Proximally, the volar plate forms the volar recess, facilitating flexion of the proximal phalanx.6 The flexor tendons and A1 pulley are directly volar to the volar plate. This confers additional stability to the volar side. The MCP joint is weakest dorsally. The dorsal capsule is thin and loose, with the extrinsic extensor tendons located directly dorsal to this capsule. The extrinsic tendons are supported by the sagittal band of the extensor hood. The sagittal band connects volarly with the transverse metacarpal ligament. The neurovascular bundle is anterior to the lumbrical muscle. This position places the bundle at risk during traumatic dislocation as well as during the volar surgical approach to the joint. The thumb MCP joint is similar to the MCP joints of the other fingers. However, because of the unique articular surfaces, the MCP joint of the thumb is more hingelike than multiaxial. Sesamoids lie anterior to the metacarpal head and articulate with it because the sesamoids are embedded in the volar plate. The flexor pollicis brevis and abductor pollicis brevis muscles partially insert into the sesamoids. Like the MCP joints of the other fingers, the thumb MCP joint is stabilized by proper collateral ligaments, accessory collateral ligaments, the joint capsule, intrinsic musculature, and extrinsic tendons. The stability of this joint is necessary for pinch and grasp. May 2009, Vol 17, No 5

Pathophysiology The usual mechanism of injury to an MCP joint is a fall on the outstretched hand causing forcible hyperextension of the joint. Dorsal dislocations (Figure 1) are more frequent than volar dislocations5 (Figure 2), and MCP joint dislocations are less common than interphalangeal dislocations. The index finger is most frequently involved, followed by the thumb.7-9 As the joint is acutely hyperextended, the volar plate is avulsed from its attachment on the metacarpal neck. In a simple (ie, reducible) dislocation, the volar plate is not interposed within the joint, and the base of the proximal phalanx remains in contact with the articular surface of the metacarpal head. The collateral ligaments may be torn, depending on the rotational force imposed during the trauma. Irreducible dislocations occur through the same mechanism of forceful hyperextension of the MCP joint. However, the volar plate becomes interposed dorsally in the joint. The metacarpal head lies prominently displaced in the palm in dorsal dislocations and is easily palpated. Kaplan3 described the pathogenesis and anatomy of irreducible dislocations. The most important structure preventing reduction is the displaced volar plate. However, the surrounding tendons and ligamentous structures form a tight noose around the metacarpal neck (Figure 3), preventing closed reduction. In the index finger, these structures usually include displacement of the lumbrical muscle radially and the flexor tendons ulnarly. At the small-finger MCP joint, the entrapping structures include the ulnar displacement of the common tendon of the abductor digiti minimi and radial displacement of the flexor tendons.10 In both cases, the metacarpal head is entrapped dis-

Figure 1

Lateral radiograph demonstrating dorsal dislocation of the metacarpophalangeal joint.

Figure 2

Oblique radiograph demonstrating volar dislocation of the metacarpophalangeal joint.

tally by the displaced natatory ligament and proximally by the superficial transverse metacarpal ligament. These structures form a tendinous noose surrounding the metacarpal neck and are tightly drawn during

319

Metacarpophalangeal Joint Dislocation

Figure 3

Figure 4

Illustration demonstrating the structures that prevent reduction of a metacarpophalangeal joint dislocation in the index finger. Any maneuvers leading to distraction or radial or ulnar deviation will tighten the structures, impeding reduction.

closed reduction maneuvers. Volar dislocation can occur through a hyperflexion or hyperextension injury. Wood and Dobyns9 reported on three cases of complex volar dislocations of the MCP joint. Because the mechanism was unclear in all three cases, they studied 10 cadaveric specimens subjected to a hyperflexion moment with a proximal translational force applied to the proximal phalanx. Five specimens developed a volar dislocation of the MCP joint, and the other five developed a transverse fracture of the proximal diaphysis of the proximal phalanx. In the five specimens with dislocation, the dorsal capsule had avulsed from the metacarpal neck and was drawn into the joint. In three of these five specimens, unilateral disruption of a collateral ligament had occurred. The authors

320

proposed that the mechanism of dislocation was hyperflexion with a proximal translational force applied to the proximal phalanx. Betz et al11 reported a case of volar MCP joint dislocation with a clearly documented hyperextension injury and proposed that volar dislocations can occur with hyperextension or hyperflexion injury. Different structures have been implicated in preventing the reduction of volar MCP joint dislocations. In addition to the dorsal capsule becoming interposed in the joint,12,13 the distal insertion of the volar plate and/or collateral ligament can be avulsed and entrapped within the joint, preventing closed reduction maneuvers.14,15 The tendinous juncture connecting the fourth and fifth extensor digitorum communis tendons may slip distal and volar to the

Oblique radiograph demonstrating an entrapped sesamoid bone.

metacarpal neck, leading to an irreducible joint.16 Orozco and Rayan17 describe entrapment of the first dorsal interosseous muscle preventing reduction of an index finger MCP dislocation. Baltas18 described entrapment of the sesamoid bone as a pathognomonic radiographic sign of entrapment of the volar plate and, thus, of an irreducible dislocation warranting open reduction (Figure 4). Tavin and Wray19 described similar findings in a patient who had radiographic signs of the sesamoid bone being interposed in the MCP joint and of the volar plate being entrapped, creating a dislocation that was irreducible by closed methods.

Patient Evaluation The typical history for a patient with dorsal dislocation of the MCP joint is a fall on an outstretched hand with a hyperextension moment at the

Journal of the American Academy of Orthopaedic Surgeons

Paul Dinh, MD, et al

MCP joint in dorsal dislocation. In a reducible dorsal dislocation, the proximal phalanx is perched in a hyperextended position on the metacarpal head with flexion of the proximal interphalangeal joint. This joint position typically appears to be more deformed than in a complex or irreducible MCP dislocation, in which the proximal phalanx lies dorsal to the metacarpal shaft in a bayonet position. The border digits and ring finger are often mildly deviated toward the adjacent more central finger. Kaplan3 described dimpling of the skin in the proximal palmar crease as a pathognomonic sign for a dorsal dislocation of the MCP joint. This finding immediately suggests the likelihood of an irreducible dislocation. Neither active nor passive motion is possible. In volar dislocations, the history may be a hyperflexion or hyperextension moment at the MCP joint. The patient may retain the ability to flex the MCP joint, but there is usually an extensor lag. Dorsally, a depression can be palpated proximal to the base of the proximal phalanx. Anteroposterior, lateral, and oblique radiographic views confirm the diagnosis. Complex dislocations usually show a widened joint space indicative of an interposed volar plate within the joint. In the thumb, the sesamoid of the conjoint tendon can be entrapped in the joint and is also indicative of a complex dislocation.16 In the other fingers, because the sesamoids are embedded in the volar plate, the presence of a sesamoid bone within the widened MCP joint should also be considered a pathognomonic sign of an irreducible dislocation.12,19 Lateral views may show the proximal phalanx lying dorsal or volar to the metacarpal head. Concomitant fractures of the base of the proximal phalanx and metacarpal head can occur in 50% of MCP joint dislocations.20,21 May 2009, Vol 17, No 5

Management Nonsurgical Simple distraction as a reduction maneuver for MCP joint dislocations is usually unsuccessful and can inadvertently convert a reducible dislocation into an irreducible one. This is because traction on the affected joint can draw the entire volar plate dorsally so that it can be completely folded between the base of the proximal phalanx and the metacarpal head. Therefore, many MCP joint dislocations require open reduction. As with any attempted closed reduction maneuver, adequate anesthesia is recommended in attempting the reduction. The closed reduction maneuver for a dorsal dislocation of the MCP joint is to flex the wrist and the proximal interphalangeal joint of the injured digit to relax the flexor tendons. Pressure is then applied from dorsal to volar to the base of the proximal phalanx. This reduction technique slides the proximal phalanx and its attached volar plate over the metacarpal head into a reduced position.12,13 Boden et al22 used a skin hook to provide traction as an assisting maneuver to successfully reduce an MCP dislocation in an 8-year-old child. When the procedure is successful, early ROM with a dorsal blocking splint is encouraged to prevent extension beyond neutral. Failed closed reduction indicates that either the volar plate is interposed in the joint or the metacarpal head has buttonholed through the palmar structures, necessitating open reduction. Dorsal dislocation of the thumb MCP joint is treated by the same reduction maneuver, but the treatment is more likely to be successful than for the other fingers. Takami et al23 reported on a series of nine dislocations of the thumb MCP joint, of which eight were treated successfully

with closed reduction. Maheshwari et al24 reported a series of 33 children with MCP dislocation of the thumb, with only 4 patients requiring open reduction. All children obtained a good result. The authors believed that because there is no deep transverse metacarpal ligament in the thumb holding the volar plate dorsally, closed reduction is often the appropriate treatment. Because the anatomy of the thumb is different from that of the other fingers, dislocations requiring surgical intervention frequently involve interposition of the volar plate, sesamoid bones, or flexor pollicis longus tendon.12,13,25,26 For volar dislocations, the reduction maneuver is similar to that for a dorsal dislocation except that the MCP joint is flexed, and gentle pressure is applied to the volar surface of the proximal phalanx as it is brought into extension. Takami et al27 reported on two cases of volar dislocation of the MCP joint of the ring finger that were successfully treated closed. The authors believed that closed reduction is possible for volar dislocations when treatment is rendered ≤2 weeks after the injury.

Surgical The original surgical approach for an irreducible dorsal dislocation, described by Farabeuf,2 uses a dorsal releasing incision. This approach has been well described in the literature.28-30 Proponents of this approach believe that it involves lower risk of neurovascular bundle injury and easier access to the entrapped volar plate than does the volar approach. In addition, it may be easier to address any associated metacarpal head fractures through the dorsal approach.28 Kaplan3 described a volar approach for treatment of irreducible dorsal dislocations. He believed the

321

Metacarpophalangeal Joint Dislocation

Figure 5

Intraoperative photograph of the volar approach to a metacarpophalangeal joint dislocation revealing the radial digital nerve (arrow) that is at risk.

volar approach allowed access not just to the volar plate, but also to the surrounding ligaments and tendons that can trap the metacarpal head and cannot be addressed through a dorsal incision. This volar approach also has been well described in the literature.31-35 McLaughlin15 delineated a variant of the volar approach that extended the incision in the proximal palmar crease to a midlateral incision along the radial side of the index metacarpal. For dislocations in the small finger, a similar incision can be used with an ulnar midlateral incision that is extended into the palm along the proximal palmar crease. Eaton and Dray36 described a technique of releasing the A1 pulley, which then releases tension on the flexor tendons and allows the proximal phalanx and attached volar plate to fall back into their anatomic positions. Of great importance during the volar approach is the vulnerability of the neurovascular bundle caused by the displaced metacarpal head (Figure 5). This displacement causes the bundle to be tented tightly and superficially, lying immediately underneath the skin.37 Green and Terry12

322

described a case in which the neurovascular bundle was transected during the initial skin incision. Using clinical and cadaveric specimens, Barry et al38 advocated the dorsal approach, an approach that Becton et al28 also found to be safer and to allow better visualization of the volar plate and of any osteochondral fractures of the metacarpal head. The senior author (S.B.S.) has performed both surgical approaches. In the fingers other than the thumb, the volar approach is preferred. Despite the risk to the radial digital nerve using this approach (Figure 5), careful dissection allows excellent visualization of the structures. Manipulating free offending structures and release of the A1 pulley is also easily done and can aid in reduction. We also agree with Hunt et al,1 who advocated release of the natatory ligament and superficial transverse metacarpal ligament, and with incising the volar plate longitudinally, as originally described by Kaplan.3 It has been suggested that the dorsal approach is a viable option, particularly when the surgeon is uncomfortable with the complex volar anatomy of the palm of the hand,23 and we concur. However, having treated several patients who presented to our institution late (>3 weeks after injury), we also recommend that both a combined dorsal and volar approach might be necessary, as indicated by Murphy and Stark.39 Particularly in these cases, we have found that, from the dorsal approach, a longitudinal incision in the middle of the volar plate can be helpful to allow the metacarpal head to more easily be relocated. Thumb MCP dislocations are usually approached from the dorsum of the thumb. However, as with the other fingers, in patients presenting late, we have found that a volar approach is helpful.

Complications Many of the complications in patients with a dislocated MCP joint are related to failure of diagnosis and appropriate treatment. Repeated attempts at closed reduction, traumatic open reduction, or prolonged dislocation may result in early degenerative arthritis or osteonecrosis of the metacarpal head. Joint stiffness is the primary complication related to this injury, possibly resulting from softtissue trauma at the time of injury or from prolonged immobilization producing excessive fibrosis, leading to a decrease ROM. Additionally, as noted by Murphy and Stark,39 delay in treatment can be associated with worse results. Joint contracture release or tenolysis may be necessary to improve final ROM. Neurovascular bundle damage can occur during open reduction because of the superficial position of the bundle over the metacarpal head. Premature closure of the physeal plate has been reported as a rare sequela of MCP joint dislocation.21

Summary Traumatic dislocation of the MCP joint is considered a rare injury, although some have observed that it may instead be underreported. Dislocations that are easily reduced without surgery are classified as simple; those that are not resolved by closed reduction and require surgery are termed complex. The metacarpal head allows for multiplanar motions of flexion, extension, abduction, adduction, and circumduction. The thumb MCP joint is more hingelike than that of the other, more multiaxial fingers. The common cause of injury to the joint is a fall on an outstretched hand, causing hyperextension, with the index finger most frequently involved. Dorsal dislocations are more common than volar dislocations. Attempts at

Journal of the American Academy of Orthopaedic Surgeons

Paul Dinh, MD, et al

closed reduction most commonly fail because the volar plate is interposed in the MCP joint or because the metacarpal head has buttonholed through the palmar structures. Surgical approaches may be dorsal or volar, although a neurovascular bundle anterior to the lumbrical muscle is at risk in the volar approach. Complications of MCP joint injury include degenerative arthritis, osteonecrosis of the metacarpal head, and stiffness, and may arise from repeated attempts at closed reduction, traumatic open reduction, or prolonged dislocation.

References Evidence-based Medicine: References 1, 3, 8-19, 23-27, 29, 33-35, 37, and 38 are case series. References 2, 4, 6, 7, 20, 22, 28, 31, 32, 37, and 38 are expert opinion. Citation numbers printed in bold type indicate references published within the past 5 years. 1.

Hunt JC, Watts HB, Glasgow JD: Dorsal dislocation of the metacarpophalangeal joint of the index finger with particular reference to open dislocation. J Bone Joint Surg Am 1967;49:1572-1578.

2.

Farabeuf LHF: De la luxation du ponce en arrière. Bull Soc Chir 1876;11:21-62.

3.

Kaplan EB: Dorsal dislocation of the metacarpophalangeal joint of the index finger. J Bone Joint Surg Am 1957;39: 1081-1086.

4.

Hubbard LF: Metacarpophalangeal dislocations. Hand Clin 1988;4:39-44.

5.

Minami A, An KN, Cooney WP III, Linscheid RL, Chao EY: Ligament stability of the metacarpophalangeal joint: A biomechanical study. J Hand Surg [Am] 1985;10:255-260.

6.

7.

8.

Zemel NP: Metacarpophalangeal joint injuries in fingers. Hand Clin 1992;8: 745-754. Malerich MM, Eaton RG, Upton J: Complete dislocation of a little finger metacarpal phalangeal joint treated by closed technique. J Trauma 1980;20: 424-425. Fultz CW, Buchanan JR: Complex fracture-dislocation of the metacarpophalangeal joint: Case report.

May 2009, Vol 17, No 5

Clin Orthop Relat Res 1988;227:255260. 9.

Wood MB, Dobyns JH: Chronic, complex volar dislocation of the metacarpophalangeal joint. J Hand Surg [Am] 1981;6:73-76.

10.

Baldwin LW, Miller DL, Lockhart LD, Evans EB: Metacarpophalangeal-joint dislocations of the fingers. J Bone Joint Surg Am 1967;49:1587-1590.

11.

Betz RR, Browne EZ, Perry GB, Resnick EJ: The complex volar metacarpophalangeal-joint dislocation: A case report and review of the literature. J Bone Joint Surg Am 1982;64:13741375.

12.

Green DP, Terry GC: Complex dislocation of the metacarpophalangeal joint: Correlative pathological anatomy. J Bone Joint Surg Am 1973;55:14801486.

13.

Glickel SZ, Barron OA, Catalano LW III: Dislocations and ligament injuries in the digits, in Green DP, Pederson WC, Hotchkiss RN, Wolfe SW (eds): Green’s Operative Hand Surgery, ed 5. Philadelphia, PA: Elsevier Churchill Livingstone, 2005, vol 1, pp 366-367.

14.

Lam WL, Fitzgerald AM, Hooper G: Volar metacarpophalangeal joint dislocation. J Accid Emerg Med 2000; 17:226-228.

15.

McLaughlin HL: Complex “locked” dislocation of the metacarpophalangeal joints. J Trauma 1965;5:683-688.

16.

Patel MR, Bassini L: Irreducible palmar metacarpophalangeal joint dislocation due to junctura tendinum interposition: A case report and review of the literature. J Hand Surg [Am] 2000;25: 166-172.

17.

Orozco JR, Rayan GM: Complex dorsal metacarpophalangeal joint dislocation caused by interosseous tendon entrapment: Case report. J Hand Surg [Am] 2008;33:555-557.

18.

Baltas D: Complex dislocation of the metacarpophalangeal joint of the index finger with sesamoid entrapment. Injury 1995;26:123-125.

19.

Tavin E, Wray RC Jr: Complex dislocation of the index metacarpophalangeal joint with entrapment of a sesamoid. Ann Plastic Surg 1998;40:59-61.

20.

Kiefhaber TR: Intra-articular fractures in joint injuries, in Hand Surgery Update. Rosemont, IL: American Society for Surgery of the Hand, 1994, pp 17-27.

21.

Lattanza LL, Choi PD: Intraarticular injuries of the metacarpophalangeal and carpometacarpal joints, in Berger RA, Weiss AP (eds): Hand Surgery, Philadelphia, PA: Lippincott Williams &

Wilkins, 2004, pp 176-179. 22.

Boden RA, Cavale N, Fleming AN: Kaplan’s puckering sign in complex dorsal dislocation of the metacarpophalangeal joint of the index finger. J Hand Surg [Br] 2006;31:576577.

23.

Takami H, Takahashi S, Ando M: Complete dorsal dislocation of the metacarpophalangeal joint of the thumb. Arch Orthop Trauma Surg 1998;118:2124.

24.

Maheshwari R, Sharma H, Duncan RD: Metacarpophalangeal joint dislocation of the thumb in children. J Bone Joint Surg Br 2007;89:227-229.

25.

Dutton RO, Meals RA: Complex dorsal dislocation of the thumb metacarpophalangeal joint. Clin Orthop Relat Res 1982;164:160-164.

26.

Coonrad RW, Goldner JL: A study of the pathological findings and treatment in soft-tissue injury of the thumb metacarpophalangeal joint: With a clinical study of the normal range of motion in one thousand thumbs and a study of post mortem findings of ligamentous structures in relation to function. J Bone Joint Surg Am 1968;50: 439-451.

27.

Takami H, Takahashi S, Ando M: Volar dislocation of the metacarpophalangeal joint of the ring finger: Report of two cases. Clin Orthop Relat Res 1999;363: 116-120.

28.

Becton JL, Christian JD Jr, Goodwin HN, Jackson JG III: A simplified technique for treating the complex dislocation of the index metacarpophalangeal joint. J Bone Joint Surg Am 1975;57:698-700.

29.

Bohart PG, Gelberman RH, Vandell RF, Salamon PB: Complex dislocations of the metacarpophalangeal joint. Clin Orthop Relat Res 1982;164:208-210.

30.

Patterson RW, Maschke SD, Evans PJ, Lawton JN: Dorsal approach for open reduction of complex metacarpophalangeal joint dislocations. Orthopedics 2008;31:1099-1102.

31.

May JW Jr, Rohrich RJ, Sheppard J: Closed complex dorsal dislocation of the middle finger metacarpophalangeal joint: Anatomic considerations and treatment. Plast Reconstr Surg 1988;82:690-693.

32.

Diao E: Metacarpal fixation. Hand Clin 1997;13:557-571.

33.

Andersen JA, Gjerløff CC: Complex dislocation of the metacarpophalangeal joint of the little finger. J Hand Surg [Br] 1987;12:264-266.

34.

Araki S, Uchiyama M, Nishimura T, Mishima S: Irreducible open dislocation of the metacarpophalangeal joint of the

323

Metacarpophalangeal Joint Dislocation small finger. J Hand Surg [Am] 1992;17: 1146-1147. 35.

36.

324

Flatt AE: Fracture-dislocation of an index metacarpophalangeal joint and an ulnar deviating force in the flexor tendons. J Bone Joint Surg Am 1966;48: 100-104. Eaton RG, Dray GJ: Dislocations and ligament injuries in the digits, in Green DP (ed): Green’s Operative Hand

Surgery. New York, NY: Churchill Livingstone, 1982, vol 1, pp 647-668. 37.

Chadha M, Dhal A: Vulnerability of the radial digital neurovascular bundle of the index finger while using Kaplan’s volar approach for irreducible dislocation of the second metacarpophalangeal joint. Injury 2004;35:1182-1184.

38.

Barry K, McGee H, Curtin J: Complex dislocation of the metacarpo-phalangeal joint of the index finger: A comparison of the surgical approaches. J Hand Surg [Br] 1988;13:466-468.

39.

Murphy AF, Stark HH: Closed dislocation of the metacarpophalangeal joint of the index finger. J Bone Joint Surg Am 1967;49:1579-1586.

Journal of the American Academy of Orthopaedic Surgeons