Carpometacarpal Joint Dislocations: Management and Long-Term Outcomes at a Specialized Hand Surgery Center in Latin America

Abstract

Carpometacarpal joint dislocations are uncommon hand injuries. These dislocations are usually misdiagnosed due to their non-specific clinical signs and tend to be difficult to identify in simple X-rays. We report our experience in the management of carpometacarpal bone dislocations at a specialized hand surgery center. Patients with carpometacarpal dislocations seen at the emergency department between 2013 and 2017 were included. All patients were treated with either closed reduction and percutaneous pinning (CRPP) or open reduction and internal fixation (ORIF). Postoperative functional assessment was performed at 6 and 18 months using the Disabilities of the Arm, Shoulder, and Hand (DASH) score. Eleven patients were included, 8 (72%) were managed with CRPP and the rest required ORIF (28%). For the functional outcome, we found an average DASH score of 27.9 at the 6 months threshold and of 1.5 at the 18 months threshold. Carpometacarpal dislocations are uncommon and easy to misdiagnose; the hand surgeon should have a high clinical suspicion in patients who sustained high-energy trauma, and imaging studies should be thoroughly evaluated. Closed reduction and percutaneous pinning is a safe and effective treatment option, with long-term good functional results.

Introduction

Carpometacarpal (CMC) joint dislocations are uncommon injuries with an estimated incidence of 1% to 1.5% in global hand trauma.¹ Due to their infrequency, these lesions tend to be overlooked or misdiagnosed; furthermore, no evidence-based guidelines have been developed for their diagnosis and management, and most data available are based on individual author’s experience, such as those published by Frick et al in 2011.²

The second to fifth CMC joints are inherently stable structures due to their surfaces and the number of dorsal, volar, and intra-articular ligaments surrounding them; meanwhile, the trapeziometacarpal joint is a biconcavoconvex joint that allows movements in multiple planes, its shape provides stability, and is further reinforced by its capsule and ligaments. Therefore, excessive axial load is required to disrupt the CMC joint’s anatomy, such as motorcycle accidents or hitting a hard surface with the fist.³ The fourth and fifth metacarpals are the most commonly injured joints; dorsal dislocations are the most common, since volar musculotendinous structures provide more stability to the palmar side.⁴

Dislocations of CMC are frequently overlooked or misdiagnosed for several reasons: clinical manifestations tend to be non-specific, swelling may obscure the deformity of the hand, while imaging evaluation of plain radiographs is difficult due to low image quality, the overlapping of bony structures, or plain inexperience from the treating physician.⁵ Up to 80% of these lesions can be associated with metacarpal or carpal bone fractures, further complicating their diagnosis and management.^2,6

The “Dr Manuel Gea Gonzalez” General Hospital is a tertiary care facility that provides medical attention to the southern and eastern areas of Mexico City, amounting to a target population of 2.5 million people.⁷ Information regarding the diagnosis, treatment, and long-term outcomes of patients with CMC dislocations is scarce in our country and developing nations in general and mostly consists of isolated case reports or anecdotal case series.⁶ The aim of this study is to document our experience in the management of CMC dislocations and present long-term outcomes of our patients.

Methods

We performed a retrospective study to identify all patients with CMC dislocation treated by our service between January 2013 and January 2017. Data were obtained from written and imaging records from the Plastic and Reconstructive Surgery Division of the “Dr Manuel Gea Gonzalez” General Hospital in Mexico City.

Every patient was evaluated by a plastic surgeon in the emergency department; diagnosis was performed by clinical examination and X-rays in anteroposterior, oblique, and lateral views. In select cases, computed tomography with 3-D reconstruction was performed. Patients with Bennett and Rolando fracture dislocation were excluded. Surgical management was carried out within the first 24 hours of arrival to the hospital. Functional assessment was conducted with Disabilities of the Arm, Shoulder, and Hand (DASH) score at 6 and 18 months.

Statistical Analysis

Data analysis was carried out with IBM SPSS Statistics, version 19.0 (IBM Corp). Quantitative data are expressed as mean ± SD, and qualitative data are expressed in terms of number and percentage. Univariate analysis was conducted for each variable, with P values calculated using Pearson χ² test or Fisher exact test for categorical variables and Student t test for continuous variables. A P value of <.05 was considered significant.

Results

During the 5-year period examined, 4751 patients presented with trauma in the upper extremities; of those, only a total of 11 patients presented CMC joint dislocations resulting in a prevalence of 0.2%. Nine patients were males (81%) and two females (18%); average age was 36.5 ± 13.35 years.

Punching was the most common mechanism of injury (8 cases, 73%), followed by blunt trauma (18%); only 1 case was related to a motor vehicle accident (9%). Three patients had concomitant fractures. Six patients had been previously evaluated in other units and given an incorrect diagnosis, arriving to our institution 3 to 20 days late.

The distribution of injuries was as follows: In 3 (27%) cases, the fourth and fifth metacarpal joints were affected, the first CMC was dislocated in 3 cases (27%), 2 patients (18%) had isolated dislocation of the fourth CMC, in one case (9%) the second CMC was involved, while 2 patients presented with triple CMC dislocations, in one case the third to fifth rays were involved, and in another the second to the fourth.

The most commonly injured ray was the fourth with 7 cases (63%), followed by the fifth (36%, 4 cases), and the thumb (27%, 3 cases); the second and third rays were injured in only 2 patients, each.

Closed reduction and percutaneous pinning (CRPP) was the most frequent treatment intervention (9 patients, 81%); the remaining patients were treated with open reduction and internal fixation (ORIF). Short-arm splint was applied in all patients for 5 to 6 weeks (Figure 1 and Figure 2). All patients were enrolled in a physical therapy program after splint removal.

Figure 1.

Patient with fourth ray carpometacarpal dislocation and fracture of the base of second metacarpal bone; preoperative X-rays (A and B) and postoperative control after closed reduction with Kirschner wires (C).

Figure 2.

Patient with fourth and fifth carpometacarpal dislocation after car crash. Preoperative images (A and B) and post-operative control after open reduction and internal fixation (C and D).

Mean DASH score at 6 months was 27.96 ± 5.05 and had a significant improvement at 18 months (1.59 ± 1.47, P < .01). Individual results can be seen in Table 1.

Table 1.

Summary of the Series of Cases.

Patient	Gender	Age (years)	Joint affected	Fracture	Treatment	DASH: 6 months	DASH: 18 months
1	Male	54	4th and 5th	–	CRPP	27.5	0
2	Male	28	4th and 5th	–	ORIF	35.8	3.3
3	Male	40	4th, 5th, and 3rd	Intra-articular metacarpal	ORIF	26.7	0
4	Male	18	4th	2nd metacarpal base	ORIF	26.7	0
5	Male	54	4th and 5th	–	CRPP	39.2	3.3
6	Female	57	1st	–	CRPP	26.7	2.5
7	Male	33	1st	Trapezoid	CRPP	23.3	1.7
8	Male	34	1st	–	CRPP	25.8	2.5
9	Female	41	2th, 3rd, and 4th	–	CRPP	24.2	0
10	Male	24	4th	–	CRPP	28.4	3.4
11	Male	19	2nd	–	CRPP	23.3	0.8

Abbreviations: CRPP, closed reduction and percutaneous pinning; DASH, Disabilities of the Arm, Shoulder, and Hand; ORIF, open reduction and internal fixation.

In their last visit, 63% of the patients referred no pain and 38% referred slight pain with movement. Only 2 patients presented long-term complications, one with decreased sensibility of the fifth finger and the other had a limited range of abduction of the fifth finger. All patients were able to return to their original jobs after treatment.

Discussion

Dislocation of the CMC joints is rare, accounting for about 1% of all hand injuries globally, and seems to be even more uncommon in Mexico. The first reports of this lesion were published by Cooper and Roux in the 19th century.⁸ Due to the low incidence of the lesion, information regarding its diagnosis and treatment tends to be limited to case reports and some case series. Furthermore, information from developing nations is lacking and almost nonexistent.

This kind of injuries are caused after applying longitudinal trauma over the metacarpal head, causing axial compression over the bone and dorsal displacement of its base, causing rupture of the stabilizing ligaments.⁹ Mobility at the CMC joint is greatest at the fifth and fourth metacarpals and is almost null in the third ray, thus explaining the increased incidence of fourth and fifth CMC dislocation.³ Even though the trapeziometacarpal joint has several anatomical differences when compared to other CMC joints, the mechanism required for its dislocation, prevalence of the injury, and its management is similar, and thus, we decided to group all lesions together.

In accordance with other series, the fourth and fifth CMCs were the most commonly affected rays; however, distribution of the rest of the lesions did not follow classic reports; our patients showed a higher incidence of first CMC dislocation and some rare configurations, such as an isolated second CMC dislocation.

Most authors recommend using bone fixation after reducing the dislocation, since the joints are usually very unstable at this point. It is our preference to use CRPP in most cases, it restores carpal alignment anatomy, allows early rehabilitation, limits soft tissue damage, maintains integrity of the joint capsule, and is economically viable to the vast majority of our patient population.¹⁰ Open reduction and internal fixation has shown adequate results in several series around the world; however, we reserve its use for complex cases, such as irreducible dislocations or if there are associated fractures.¹¹ Even though no treatment modality has proven to be superior in randomized controlled trials, studies by Bao et al. and Gülabi et al found that patients managed by CRPP had better DASH scores and grip strength than those treated with ORIF.^12,13

Surgery should be ideally performed during the first 7 to 10 days after injury⁵; however, we performed successfully 1 case even at the 20th day. Physiotherapy of hand and wrist joint is required after 6 weeks of wrist immobilization in safety position to avoid postoperative stiffness.¹⁴

Late diagnosis and misdiagnosis are very frequent, amounting to over half of our patients, and this coincides with the results from Henderson and Arafa, who reported 15 overlooked CMC dislocation cases in their series of 21 patients.¹⁵ Clinical signs of CMC dislocation are often nonspecific and are limited to edema, dorsal deformation, limited range of motion, or finger misalignment in severe cases, while X-ray images can be difficult to interpret due to overlapping of structures. In order to adequately identify CMC dislocations in simple radiographs, good anteroposterior, true lateral, and oblique images should be taken and carefully examined. Identification of Gilula’s lines and the parallel M lines described by Fisher are 2 good radiographic signs that can help systematize the evaluation.¹⁶ In select cases, computed tomography scans allow the surgeon to better visualize alterations in hand architecture, identify associated injuries, and are increasingly employed for preoperative planning.²

The DASH score has proven to be an effective tool for monitoring the effectiveness of treatment in hand surgery. In our cohort, all patients showed adequate recovery and were able to return to work, an important measure of success, since great part of our patients are manual laborers.

The main limitation of our study is its small patient sample and retrospective nature. However, it represents the largest series of CMC in Latin America, and our outcome findings serve to demonstrate that CRPP is a valid and effective treatment option for this group of patients.

Summary

Carpometacarpal dislocations are uncommon and easy to misdiagnose; the hand surgeon should have a high clinical suspicion in patients who sustained closed-fist injuries or after high-energy trauma, and imaging studies should be thoroughly evaluated. Closed reduction and percutaneous pinning is a safe and effective treatment option, with long-term good functional results.