Carpometacarpal dislocation with impending compartment syndrome

J. Mohan Kumar

Consultant Orthopaedician and Arthroscopy Surgeon, Kauvery Hospital, Electronic City, Bengaluru, India

Abstract

Carpometacarpal (CMC) joint fracture-dislocation is a rare hand injury associated with high-energy trauma. Due to severe swelling and overlapping of bones on the radiograph of wrist-hand, dislocations are missed. If left untreated, it can lead to compartment syndrome and poor long-term outcomes. We present a case of second and third CMC joint dislocation with impending compartment syndrome in a 23-year-old male patient.

Introduction

Traumatic fracture-dislocations of carpometacarpal (CMC) joints are rare injuries that present in less than 1% of hand and wrist injuries [1]. CMC joint dislocation occurs with other associated fractures. Most CMC joint dislocations are missed on X-ray of wrist joint and hand due to overlapping of bones [2]. Severity of displacement depends on position of hand, wrist and intensity of force applied. Dorsal CMC joint dislocations are more common than volar CMC joint dislocations. Delayed treatment of CMC dislocations results in poor functional outcome and chronic residual pain. Delay in diagnosis and treatment can lead to compartment syndrome also.

Case Presentation

We present a case of 23-year-old gentleman, who was involved in a road traffic accident and sustained a hyperflexion injury to his right wrist. He was brought to our emergency room three hours post-injury, with swelling around the wrist and severe pain.

Initial radiographs (Fig. 1) showed carpometacarpal dislocation which was confirmed by CT scan (Fig. 2). Patient had severe pain with gross swelling (Fig. 3) and inability to move his fingers and paraesthesia.

Fig. 1. AP & Lateral Radiograph of wrist Showing CMC dislocation.

Fig 2. CT scan of wrist.

Fig. 3. Pre-op Clinical picture

With this clinical picture, a diagnosis of second and third carpometacarpal dislocation with impending compartment syndrome was made and the patient immediately shifted to Operation theatre.

Under regional anaesthesia, through a dorsal approach, the carpometacarpal joints were reduced and fixed with K wires (Fig. 4). Through the same incision faciotomy (Fig. 5) was performed; muscles were responsive to stimuli. Wound was partially closed and below elbow volar Slab was applied.

Fig. 4. Intra Op Fluroscope image.

Fig 5. Intra Op picture showing Fasciotomy wound.

Post operatively swelling settled with good vascularity of the fingers. 6 weeks post-op, K wires were removed and mobilization started.

Radiograph showing congruent joint with reduced carpometacarpal joint is posted as Fig. 6.

Fig. 6. Three months Post-Op

Discussion

CMC joints are saddle joints that are stabilised by volar and dorsal ligaments, transverse metacarpal ligaments, long flexor and extensor tendons, and intrinsic muscles of hand. Dorsal ligaments are stronger than volar ligaments. Furthermore, ulnar sided CMC joints are more mobile than radial CMC joints. The third metacarpal articulation with the capitate is a “key-stone” due to its more proximal location than the carpal articulations of the other metacarpals.

High-velocity injury is the most common mechanism of injury for CMC dislocation [3,4]. On the anteroposterior radiograph, evaluation of CMC joint is done by parallel “M lines” as described by Gilula [5] (Fig. 7). In lateral radiograph, it is important to assess the direction of displaced CMC joint fracture-dislocation. Computed tomography is used to diagnose occult fractures.

Fig. 7. M lines of Gilula.

CMC joint fracture dislocation can be treated by close reduction immobilisation, close reduction internal fixation or open reduction internal fixation with K-wires. In our case we did a dorsal approach and open reduction of CMC joint performed and stabilised with K wire. Fasciotomy wound was secondarily sutured after 2 weeks.

Conclusion

To conclude, CMC joint fracture dislocation is an extremely rare injury that needs thorough clinical examination and radiological assessment. Missed diagnoses are frequently reported. Hence, CMC joint fracture dislocation should be considered while doing careful examination of the hand injury, in addition to studying a true lateral X-ray of wrist and hand. Compartment syndrome is very much a possibility in these injuries and hence treatment should not be delayed. Early open reduction and internal fixation are required for excellent functional results of the hand injury.

References

Sharma AK, John JT. Unusual case of carpometacarpal dislocation of all the four fingers of ulnar side of hand. Med J Armed Forces India. 2005;61(2):188-9.
Henderson JJ, Arafa MA. Carpometacarpal dislocation: an easily missed diagnosis. J Bone Joint Surg Br. 1987;69(2):212-4.
de Beer JD, Maloon S, Anderson P, et al. Multiple carpo-metacarpal dislocations. J Hand Surg Br. 1989;14(1):105-8.
Breiting V. Simultaneous dislocations of the bases of the four ulnar metacarpals upon the last row of carpals. Hand. 1983;15(3):287-9.
Gilula LA. Carpal injuries: analytic approach and case exercises. AJR Am J Roentgenol. 1979;133(3):503-17.

Carpometacarpal dislocation with impending compartment syndrome