Case Report: Osteochondral Fragment—A Rare Cause of Locked Metacarpophalangeal Joint

doi:10.4236/ss.2011.26076

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Surgical Science, 2011, 2, 353-355

doi:10.4236/ss.2011.26076 Published Online August 2011 (http://www.SciRP.org/journal/ss)

Case Report: Osteochondral Fragment—A Rare Cause of

Locked Metacarpophalangeal Joint

Kelvin Ramsey, S. Overstall, A. Fleming

St. George’s Ho sp ital, London, UK

E-mail: [email protected]

Received April 1, 2011; revised May 2, 2011; accepted Ju ly 14, 2011

Abstract

We describe the presentation of a patient with sudden, sharp pain associated with a snapping sensation,

swelling and pain over the metacarpophalangeal joint (MCPJ) with no history of direct trauma. The finger

was held in 30 degrees of flexion and significantly deviated to the ulnar side with loss of extension. A diag-

nosis of traumatic rupture of the radial sagittal band of the extensor mechanism was made but the cause at

exploration was found to be impingement of an osteochondral fracture fragment. This is a rare cause of irre-

ducible loose body “locking” of the metacarpophalangeal joint.

Keywords: Metacarpophalangeal Joint, Locking, Osteochondral, Fragment

1. Introduction

A 72 year old, right-handed female rheumatoid arthritis

patient was referred to our department with an acutely

painful, swollen left middle finger. One week prior to

arrival she had picked up a kettle and noticed a sudden,

sharp pain associated with a snapping sensation. The

finger immediately became swollen and painful over the

dorsum of her third metacarpophalangeal joint (MCPJ)

and she noticed that she was unable to fully straighten

the digit. There had been no history of direct trauma to

the affected hand.

On examination the left middle finger was held in 30

degrees of flexion and significantly deviated to the ulnar

side, lying underneath the ring finger (Figure 1). The

MCPJ was swollen and tender. Active extension was not

possible and passive extension was painful. Flexor digi-

torum superficialis and profunda function were intact

with full passive interphalangeal joint range of motion.

There were no palpable nodules on the volar aspect nor

any other abnormal findings. On close inspection of the

radiograph, a small abnormality was visible on the volar

aspect of the joint, of uncertain significance given the

clinical picture (Figure 2).

The diagnosis of traumatic rupture of the radial sagit-

tal band of the extensor mechanism was made, and the

patient was listed for semi-urgent repair.

Under regional anaesthesia the finger was still held in

30 degrees of flexion and passive extension was not pos-

sible. The extensor mechanism was explored using a

curvilinear incision over the dorsum of the MCPJ. The

extensor tendon was found to lie perfectly in th e midline

and the sagittal bands were intact.

The volar aspect of the finger (o v er the A1 pu lley) was

exposed to exclude an impacted trigger finger. A small

incidental flexor sheath ganglion was found and excised

but the flexor tendons were running freely prior to this.

The MCP joint capsule was then opened and explored.

Lying within the joint on the dorsal aspect of the meta-

Figure 1. Left middle finger held in 30 degrees of flexion

and significantly deviated to the ulnar side.

K. RAMSEY ET AL.

354

Figure 2. Pre-operative radiograph showing a small ab-

normality on the volar aspect of the joint but nothing seen

dorsally.

carpal head was a small osteochondral fragment, which

was impinging at the point of articulation with the base of

the proximal phalanx and preventing extension of the joint.

This fragment had fractured from the ulnar aspect of the

head of the metacarpal on the palmar side and migrated

within the joint capsule (Figures 3 and 4). This was re-

moved and the joint irrigated (Figure 5). The passive

range of movement of the joint returned to normal. The

wound was closed and the hand placed in a resting splint.

The patient was referred to hand therapy for immedi-

ate mobilization and made a full recovery.

2. Discussion

We suggest that this represents a rare cause of irreducible

loose body “locking” of the metacarpophalangeal joint,

resulting in ulnar deviation and masquerading as a sagit-

tal band rupture. The pre-operative radiograph, with the

benefit of retrospect, showed small fragments at the site

of fracture but did not explain the cause of the locking

nor was the main fragment, which was causing im-

pingement within the joint, visible.

There have been numerous reports of isolated “locked

fingers” in the literature. This is commonly confused

Figure 3. Site of fracture of osteochondral fragment from

ulnar aspect of metacarpal head on volar aspect.

Figure 4. Small osteochondral fragment found lying within

the joint on the dorsal aspect of the metacarpal head.

Figure 5. Osteochondral fragment after removal.

K. RAMSEY ET AL.

355

with triggering of the flexor tendon under the A1 pulley

[1]. True locking can occur when the volar plate or col-

lateral ligament catches on an osteophyte [2] or abnor-

mally shaped metacarpal head. Other causes include:

entrapment of a sesamoid bone behind an exostosis of

the metacarpal head, subluxation of the dorsal interosse-

ous tendon over a dorsal exostosis [3], foreign bodies

within the flexor sheath [4], volar plate interposition,

volar plate haemangioma [5] or gouty degeneration of

the MCP joint. The successful treatment of a locked fin-

ger with gentle manipulation under regional anaesthesia

has also been described [6,7] but this was not possible in

our case. Forced manipulation of a locked finger has also

been described as a cause of intra-articular fractures [8].

Spontaneous rupture of the sagittal bands with subse-

quent subluxation of the extensor tendon is a common

finding in patients with rheumatoid arthritis. It may also

follow forced flexio n of the finger in the non-rh eumatoid

patient. It more commonly affects the middle finger, and

the radial sagittal band ruptures more commonly than the

ulnar band, resulting in ulnar deviation and extensor lag.

The presentation of this condition is identical to that

described in our case, and justifies our initial diagnosis.

However, this rare cause of joint locking due to fracture

fragment (despite minimal injury) illustrates the impor-

tance of considering alternative diagnoses even in the

most clear-cut clinical presentation.

3. References

[1] M. A. Posner, V. Langer and S. M. Green, “The Locked

Metacarpophalangeal Joint: Diagnosis and Treatment,”

Journal of Hand Surgery, Vol. 11, No. 2, 1986, pp.

249-253.

[2] B. Vinnars, S. Bystrom and F. af Ekenstam, “Entrapment

of the Metacarpophalangeal Joint of the Middle Finger.

Case Report,” Scandinavian Journal of Plastic and Re-

constructive Surgery and Hand Surgery, Vol. 30, No. 3,

1996, pp. 231-233. doi:10.3109/02844319609062821

[3] R. Q. Terrill and R. J. Groves, “The Locked Metacarpo-

phalangeal Joint: Report of Four Cases and Review of the

Literature,” Contemporary Orthopaedics, Vol. 29, No. 2,

1994, pp. 121-125.

[4] S. Rajasekaran, “Locked Finger Due to Foreign Body in

the Flexor Sheath,” Journal of Hand Surgery, Vol. 16, No.

4, 1991, pp. 460-461.

doi:10.1016/0266-7681(91)90028-M

[5] G. Fernandez, “Locking of a Metacarpophalangeal Joint

Caused by a Haemangioma of the Volar Plate,” Journal

of Hand Surgery, Vol. 13, No. 3, 1988, pp. 323-324.

doi:10.1016/0266-7681(88)90100-3

[6] M. Yagi, K. Yamanaka, K. Yoshida, et al., “Successful

Manual Reduction of Locked Metacarpophalangeal Joints

in Fingers,” Journal of Bone and Joint Surgery, Vol. 82,

No. 3, 2000, pp. 366-371.

[7] A. B. Vernet, S. Lopez-Sicilia and C. Villas, “Metacar-

pophalangeal Subluxation: Locked Finger,” Archives of

Orthopaedic and Trauma Surgery, Vol. 104, No. 6, 1986,

pp. 339-341. doi:10.1007/BF00454426

[8] G. Inoue, R. Nakamura and T. Miura, “Intra-Articular

Fracture of the Metacarpal Head of the Locked Index

Finger Due to Forced Passive Extension,” Journal of

Hand Surgery, Vol. 13, No. 3, 1998, pp. 320-322.

doi:10.1016/0266-7681(88)90099-X