Traumatic Isolated Thumb Carpometacarpal Joint Dislocation - Report of Two Clinical Cases^*

Abstract

Isolated thumb carpometacarpal joint dislocation is a rare lesion that accounts for less than 1% of all hand lesions. The authors present two cases of traumatic isolated thumb carpometacarpal joint dislocation. One of them was treated with closed reduction and cast immobilization, and the other was treated with closed reduction, Kirschner-wires pinning, and cast immobilization. The first patient had a good functional outcome and showed no signs of thumb carpometacarpal instability. The patient treated with Kirschner wires presented signs of clinical instability and radiological subluxation. Isolated thumb carpometacarpal dislocation is a rare lesion that can cause joint instability, which interferes with the normal function of the hand and can lead to articular degenerative changes. The best management of this lesion is still controversial, since there is lack of evidence in the literature showing superiority of one treatment over the other.

Keywords:
joint dislocations; thumb; hand

Resumo

A luxação traumática isolada da articulação trapézio-metacárpica é uma lesão rara que faz parte de menos de 1% de todas as lesões de mãos.

Os autores apresentam dois casos de luxação traumática isolada da articulação trapézio-metacárpica. Um dos casos foi tratado com redução fechada e imobilização com gesso, e o outro foi tratado com redução fechada, fixação com fios Kirschner, e imobilização com gesso.

O primeiro paciente teve um bom resultado funcional e não mostrou sinais de instabilidade trapeziometacarpal. O paciente tratado com fios Kirschner apresentou sinais de instabilidade clínica e subluxação radiológica. A luxação isolada da articulação trapeziometacarpal é uma lesão rara que pode causar instabilidade articular que interfere com a funcionalidade normal da mão e pode resultar em mudanças articulares degenerativas.

O melhor manejo dessa lesão ainda é controverso, já que ainda faltam evidências na literatura que mostrem a superioridade de um tratamento em relação ao outro.

Palavras-chave:
luxação articular; polegar; mão

Introduction

Isolated thumb carpometacarpal joint dislocation is a rare lesion that accounts for less than 1% of all hand lesions.¹–⁴ The most common mechanism of injury involves an axial force applied on a partially flexed thumb.¹–³,⁵,⁶

The gold standard treatment remains unclear. Treatment choices range from closed reduction and cast immobilization and closed reduction and pinning with Kirschner wires (Kwires) to open reduction with capsular repair and ligament reconstruction.¹–¹⁰

The first carpometacarpal joint is a saddle-shaped joint that is responsible for the extraordinary mobility and important function of the thumb.¹ If this dislocation is misdiagnosed or inadequately treated, it can lead to chronic mechanical instability, hand disability, and articular degenerative changes.⁴,⁹

The authors present two cases of traumatic isolated thumb carpometacarpal joint dislocation. One of them was treated with closed reduction and cast immobilization, and the other was treated with closed reduction, K-wires pinning, and cast immobilization.

Case Report 1

A 25-year-old male fell while riding a bicycle and injured his left hand.

He presented to the emergency department complaining of pain, deformity, and edema in his left thumb.

Oblique and anteroposterior hand X-rays revealed an isolated carpometacarpal dislocation of the thumb (►Fig. 1).

Closed reduction was easily performed, and the joint was immobilized with a cast splint for 4 weeks.

At the 3 months follow-up, the patient was asymptomatic, showed no instability signs, and presented total range of motion and normal grip strength.

The 6-months follow-up X-ray showed no signs of subluxation or articular degenerative changes (►Fig. 2).

Fig. 1
Isolated carpometacarpal dislocation of the thumb.

Fig. 2
Six-month follow-up.

Case Report 2

A 56-year-old male was admitted in the emergency department after falling and injuring the left hand while playing soccer.

He complained of pain and deformity in his left thumb. Anteroposterior, lateral and oblique hand radiographs showed a trapeziometacarpal dislocation, without fracture signs (►Fig. 3).

Closed reduction, K-wire pinning, and cast immobilization were performed under general anesthesia (►Fig. 4). The immobilization device was removed 5 weeks later, and the patient started functional rehabilitation.

The 1-year follow up X-ray showed a trapeziometacarpal subluxation, and dorsal-volar instability was evident on clinical examination (►Fig. 5). Open reduction with capsular-ligament reconstruction was advised, but the patient refused surgical treatment.

Discussion

The first carpometacarpal joint presents a unique configuration that allows a wide range of stable motion, including flexion/extension, abduction/adduction and opposition/retropulsion.¹,⁵ A screw-home torque mechanism (metacarpal internal rotation, tightening of the dorsoradial ligaments and locking of the metacarpal volar beak into trapezium) is responsible for the dynamic force that transforms a lax static joint to a stable congruent joint in opposition, permitting a strong pinching and grasping.¹ Joint stability depends on articular congruency, capsule integrity, and volar/dorsal ligaments function.⁴

There is much controversy in the literature about which of the 16 exiting ligaments is the most important stabilizer of trapeziometacarpal joint. First, the anterior oblique ligament was thought to be the primary stabilizer, but later, Harvey and Bye¹¹ and Pagalidis et al¹² defended that the most important ligament was the posterior oblique ligament. The biggest cadaveric study conducted by Strauch et al¹³ showed that the dorsoradial ligament complex is the main responsible for the joint stability, confirming what Shah and Patel¹⁴ said in 1983. Both patients discussed presented dorsal dislocation, but the authors could not specify which ligament was ruptured because they used closed treatment techniques.

Fig. 3
Isolated trapeziometacarpal dislocation.

Fig. 4
Postoperative X-ray.

Hand or thumb X-rays are usually sufficient to diagnose carpometacarpal dislocations, but associated lesions must be ruled out carefully. Computed tomography could be used to exclude bone associated lesions. Ultrasonography and magnetic resonance imaging are useful for evaluating ligamentous injuries and for surgical planning.⁹

Thetreatment of choice in this kind of lesion is still indebate (►Table 1_.)¹,⁴–¹⁰,¹⁴–²¹ Closed reduction and immobilization is advocated by some authors, such as Kahn et al²⁰ and Bosmans et al,¹ who showed good functional outcome without recurrence of instability, like the authors described in the first clinical case. Closed reduction and pinning with K-wires is a technique that presents variable results, with some cases of follow-up subluxation and instability, similar to the patient referred in clinical case 2. Open reduction and repair or reconstruction of the capsule and ligaments are described by numerous authors with different techniques, but they are insufficient for primary surgical treatment recommendation.²²

Fig. 5
Trapeziometacarpal subluxation at the 1- year follow-up.

The authors think that a careful instability evaluation after closed reduction is essential for the treatment choice. Khan et al²⁰ defend that failure to maintain closed reduction, acute instability, significant swelling, or delayed presentation are surgical treatment indications.

A surgical step-wise approach may be a wise choice, selecting ligament reconstruction in case of loss of reduction after K-wire pinning.

Table 1
Literature references

Literature references		Treatment	Patient complains	Radiographs
Shah and Patel14	1983	2 open reductions and K-wires pinnings	No	Subluxation
		1 closed reduction and K-wires pinning	No	–
		1 open reduction	No	–
Chen15	1987	1 ligament reconstruction	No	–
Watt and Hopper16	1987	9 closed reductions and cast immobilizations	3 mild symptoms	2 subluxations, 1 persistent luxation
		3 closed reductions and K-wires pinnings	2 mild discomfort	1 subluxation
Jakobsen and Elberg17	1988	1 closed reduction and K-wires pinning	No	Subluxation
Simonian and Trumble18	1996	8 closed reductions and K-wires pinnings	3 pain	4 subluxations
		9 ligament reconstructions	1 mild discomfort	3 joint narrowings
Kural et al19	2002	1 closed reduction and cast immobilization	No	–
Khan et al20	2003	2 closed reductions and cast immobilizations	No	–
Bosmans et al1	2008	closed reduction and cast immobilization	No	–
Fotiadis et al6	2010	1 ligament reconstruction	No	–
Jeong et al4	2012	1 closed reduction and K-wires pinning	No	–
		1 ligament reconstruction	Stiffness	–
Chan8	2013	1 closed reduction and cast immobilization	No	–
Iyengar et al10		1 closed reduction and K-wires pinning	Pain	Subluxation
McCarthy and Awan7	2014	1 closed reduction and cast immobilization	No	–
Ansari et al9	2014	3 ligament reconstructions	1 Mild pain	–
Annappa et al3	2015	1 ligament reconstruction	No	–
Lahiji et al5	2015	5 ligament reconstructions	No	–
		1 closed reduction and cast immobilization	No	–
Slocum et al21	2019	1 closed reduction and cast immobilization	No	–

• Abbreviation: K-wires, Kirschner wires.

Conclusion

Isolated thumb carpometacarpal dislocation is a rare lesion that can cause joint instability, which interferes with the normal function of the hand and can lead to articular degenerative changes.

The current literature is insufficient to choose one treatment option over the other and therefore; thus, the best management of this lesion is still controversial. The authors believe that the treatment of choice depends on anatomic restauration and joint instability degree.

• Financial Support
  There was no financial support from public, commercial, or non-profit sources.

References

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• ²
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  Shah J, Patel M. Dislocation of the carpometacarpal joint of the thumb. A report of four cases. Clin Orthop Relat Res 1983;(175):166–169
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  Jakobsen CW, Elberg JJ. Isolated carpometacarpal dislocation of the thumb. Case report. Scand J Plast Reconstr Surg Hand Surg 1988;22(02):185–186
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Publication Dates

• Publication in this collection
  29 Sept 2021
• Date of issue
  Jul-Aug 2021

History

• Received
  30 July 2019
• Accepted
  12 Dec 2019