Journal of Postgraduate Medicine
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CASE REPORT
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Year : 1996  |  Volume : 42  |  Issue : 1  |  Page : 30-1  

Irreducible dislocation of the interphalangeal joint of the thumb.

BV Mohan, SS Kishan, PP Munshi, RH Pathak, HH Pandit 
 Department of Orthopaedics, Dr RN Cooper Municipal Hospital and Seth GS Medical College, Mumbai.

Correspondence Address:
B V Mohan
Department of Orthopaedics, Dr RN Cooper Municipal Hospital and Seth GS Medical College, Mumbai.

Abstract

Two cases of posttraumatic irreducible compound dislocation of the interphalangeal joint of the thumb are presented. This rare injury requires surgical intervention with anatomic repositioning of the structures responsible for the irreducibility viz. the long Flexor tendon and the volar plate.



How to cite this article:
Mohan B V, Kishan S S, Munshi P P, Pathak R H, Pandit H H. Irreducible dislocation of the interphalangeal joint of the thumb. J Postgrad Med 1996;42:30-1


How to cite this URL:
Mohan B V, Kishan S S, Munshi P P, Pathak R H, Pandit H H. Irreducible dislocation of the interphalangeal joint of the thumb. J Postgrad Med [serial online] 1996 [cited 2022 May 17 ];42:30-1
Available from: https://www.jpgmonline.com/text.asp?1996/42/1/30/460


Full Text




  ::   IntroductionTop


The interphalangeal joint of the thumb is an inherently stable joint because of the stability provided by the strong insertions of the long flexor and extensor tendons of the thumb, the strong collateral ligaments and the short lever arm of the distal phalanx. Hence, dislocations of the interphalangeal joint are uncommon. Still rare are irreducible dislocations of these joint. We have treated two such irreducible compound dislocations of the interphalangeal joint of the thumb over the last year. In each case, an unusual intraarticular block to reduction could be demonstrated.


  ::   Case reportsTop


Two patients, both of them young male adults in their early twenties, sustained open dorsal dislocations of the interphalangeal joint of their dominant thumbs, upon failing on their outstretched hands. X-rays showed rotation of the distal phalanges in addition to the dorsal dislocation. [Figure:1]

An attempt at reduction by manipulation, under general anaesthesia was unsuccessful in both patients, following which surgical reduction was carried out.

The interphalangeal joint was exposed by extending the wound on the volar aspect of the thumb. The operative findings included a torn ulnar collateral ligament, a ruptured and dorsally displaced volar plate, a dorsally displaced tendon of the Flexor Pollicis Longus, wrapped around and dorsal to the ulnar condyle of the proximal phalanx of the thumb.

The volar plate was avulsed near its proximal attachment and was displaced along with the distal phalanx dorsal to the head of the proximal phalanx. The long Flexor tendon and the volar plate were gently manipulated into their normal anatomical positions and the dislocation was reduced. The volar plate was repaired using 50 Prolene. Once reduction of the dislocation was achieved and the volar plate sutured, the joint appeared to be stable and no additional fixation was deemed necessary. [Figure:2]

A wash was given and the wound closed. The joint was immobilised in a gutter splint, in a neutral position, for three weeks. The wounds healed primarily without any complication. Initial stiffness was noted after the three weeks of immobilisation, which improved significantly with aggressive active physiotherapy and with no residual functional disability.


  ::   DiscussionTop


The interphalangeal joint of the thumb occupies a position of unique importance in the hand. For this reason, utmost care and concern should be given to this injury since loss of motion at this joint could severely restrict function.

Very little is found in literature regarding this type of injury. Salamon and Gelberman[1] have reported the largest series so far. In their three cases, two mechanisms of injury were described. The first mechanism (one case) involved a hyperextension and rotational deforming force leading to rupture of the collateral ligament on one side and the proximal attachment of the volar plate with displacement dorsal to the condyles of the proximal phalanx of the now torn volar plate along with the long Flexor tendon, thus locking the joint preventing reduction. The rotational deformity of the distal phalanx was appreciated on radiographs. The second mechanism (two cases) involved a pure hyperextension force leading to failure of both collateral ligaments as well as the proximal attachment of the volar plate, which then was displaced dorsal to the condyles of the proximal phalanx preventing reduction.

The two cases we present are similar to the first one documented by Salamon and Gelberman. The mechanism of injury, we feel, is as follows: hyperextension and rotation of the distal phalanx of the thumb, causing failure of the ulnar collateral ligaments, the proximal attachment of the volar plate (being thinner) as well as the dorsal capsule ulnar to the tendon of the Extensor Pollicis longus sequentially, leading to the dislocation of the joint. Further deformation, probably mainly as a rotational torque, causes the tendon of the long Flexor and the volar plate to slip dorsally around and over the condyles of the proximal phalanx, to now lock the joint in dorsal dislocation.

The dislocation was compound in both our cases, the wound being on the volar aspect of the joint, with the condyles of the proximal phalanx exposed through the skin. Open wounds are common at this site due to the, rather snug attachments of the soft tissue structures (Eaton).

Eaton[2] has also seen the fact that no additional repair is necessary for joint stability after careful reduction and suturing of the volar plate earlier.

In conclusion, two cases of irreducible compound dislocation of the interphalangeal joint of the thumb are presented for their rarity as well as the protocol of management. Surgical reduction is mandatory and repair need be done of only the ruptured volar plate with no sacrifice of joint stability and subsequent hand function.

References

1 Salamon PB, Gelberman RH. Irreducible dislocation of the interphalangeal joint of the thumb. A report of three cases. J Bone Joint Surg 1978; 60A(3):No 3, 400401.
2Eaton RG. Joint injuries of the hand. Springfield: Illinois Charles C Thomas; 1971.

 
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