Pathoanatomy and treatment modifications of metacarpophalangeal joint locking of the thumb

Locked thumb metacarpophalangeal joint due to sesamoid bone entrapment: A case report and review of literature

Locked thumb metacarpophalangeal (MCP) joint has been known as a relatively rare condition. We present a case of a 25-year-old male presented with a traumatic locked thumb MCP joint of the right hand. Clinical presentation showed the joint was in a hyperextention position and resistant to active flexion and extension. The radial sesamoid was distally displaced on X-ray film and entrapped into the joint on CT scan. The mechanism of the locked MCP joint was thought as a "pull-hook lock" between the pointed proximal edge of the sesamoid and the deformed volar groove on the cartilaginous surface of the metacarpal head. Surgical treatment included partially releasing the insertion of the abductor pollicis brevis (APB) and flexor pollicis brevis (FPB) muscles to move the entrapped radial sesamoid, and resurfacing the deformed metacarpal head.

Treatment for the recurrent case of locking of the metacarpophalangeal joint of the thumb: A case report

BACKGROUND

Locking of the metacarpophalangeal (MP) joint of the thumb is a rare condition caused by hyperextension injury. Cases are treated by closed reduction, but open reduction is occasionally required.

CASE PRESENTATION

Herein, we report a recurrent case of locking of the MP joint. Closed reduction was successful for treatment of the first injury but unsuccessful for the second injury, and open reduction was performed. At the operation for the second injury, we observed a transverse groove on joint cartilage of the metacarpal head.

CONCLUSION

In recurrent cases, we should assume the possibility of failure of closed reduction and prepare for open reduction.

Locking of the Metacarpophalangeal Joint of the Thumb Caused by Entrapment of the Radial Sesamoid Bone

Locking of metacarpophalangeal (MCP) joints of the thumb may be a consequence of dorsal subluxation from hyperextension injury. The joint is locked in mild hyperextension and cannot flex actively or passively. We report four patients with locked MCP joint of the thumb due to radial sesamoid entrapment after hyperextension or forced flexion injury. All patients had a prominent radial condyle of the metacarpal bone. Three patients had a deformity of the longitudinal groove on which the sesamoid was overlaid. The radial sesamoid was entrapped proximal to the radial condyle which could result in limited extension and hinged flexion of the joint. Excision of the radial sesamoid could release the locked joint. The radial sesamoid should be assessed if the motion of the thumb MCP joint is limited after flexion or extension injury.

Level of Evidence: Level V (Therapeutic)

Use of Magnetic Resonance Imaging for Orthopedic Trauma and Infection in the Emergency Department

Conditions affecting the musculoskeletal system constitute a significant portion of medical emergencies in the United States, with traumatic injury and infection being two of the most common etiologies. Although physical examination and plain radiographs are often sufficient to guide diagnosis and treatment, there are myriad traumatic and infectious pathologies that are commonly missed or simply not detectable on plain radiographs. Advanced imaging is subsequently warranted for additional workup.Magnetic resonance imaging (MRI) has become an increasingly used imaging modality for musculoskeletal complaints in the emergency department due to its superior visualization of soft tissues, focal edematous changes, and occult osseous insults often not visible on plain radiographs. Although multiple studies have evaluated its utility in the workup of emergency musculoskeletal complaints, there remains a dearth of literature examining the use of MRI for certain occult diagnoses.Radiologists, emergency clinicians, and orthopedic surgeons must be knowledgeable of the indications for MRI in the emergency setting, as delayed diagnosis may contribute to increased morbidity and possibly mortality. This review summarizes the use of MRI in diagnoses relating to trauma or infection among patients presenting to the emergency department with a musculoskeletal complaint.

Ultrasound diagnosis and follow-up of a locked thumb metacarpophalangeal joint caused by radial sesamoid entrapment: a case report

Background

A locked thumb metacarpophalangeal joint is a rare condition that presents as restricted joint motions with mild hyperextension deformity, usually after a relatively minor hyperextension injury. Owing to the limitations of radiographs, computed tomography is a useful diagnostic imaging modality for assessing sesamoid displacement. However, despite its convenience, ultrasound findings of the locked thumb have rarely been reported. Here, we report a case of a locked thumb metacarpophalangeal joint diagnosed and followed-up using ultrasound.

Case presentation

A 15-year-old boy with a locked thumb metacarpophalangeal joint presented to our hospital. On physical examination, the 1st metacarpophalangeal joint was found to be hyperextended, and active and passive flexions were not possible. While radiographs were inconclusive, ultrasound revealed radial sesamoid entrapment at the 1st metacarpophalangeal joint causing locking. After closed manual reduction, metacarpophalangeal motions recovered. Success of the reduction was also confirmable by ultrasound.

Conclusions

Ultrasound can be a feasible modality to diagnose a locked thumb metacarpophalangeal joint and immediately judge the success or failure of the reduction.

Treatment of Locking of the Metacarpophalangeal Joint of the Thumb

Locking of the thumb metacarpophalangeal joint is a relatively rare condition. We report successful treatment in 11 cases of locking of the thumb. Ten patients were diagnosed at an average of 3.2 days (range: 0-21 days) from the injury onset, whereas one patient was diagnosed at 4 months from the injury. Seven of 11 cases underwent successful manual reduction, whereas the other four cases required surgical treatment. Among the surgically treated cases, all cases had a sharp prominent of the radial condyle of the metacarpal head. Therefore, this case series showed 1 chronic case and 4 of 10 cases with a nonround shape of metacarpal heads requiring open reduction.

Treatment of a Subacute Locked Thumb Metacarpophalangeal Joint with Sesamoid Entrapment

Introduction

Locked thumb metacarpophalangeal (MCP) joints due to entrapped radial sesamoids are rare injuries that commonly require open reduction, especially when the injury is delayed in presentation.

Case Presentation

We present a case of a 24-year-old female with a subacute thumb MCP joint subluxation due to an incarcerated radial sesamoid. She underwent successful closed reduction but had persistent pain and difficulty gripping large objects necessitating eventual open volar plate repair despite therapy. She was able to achieve full motion, with little pain and disability, after undergoing delayed volar plate repair.

Discussion

Delayed volar plate repair may be considered for those patients who fail to improve with conservative management and occupational therapy after a successful closed reduction for thumb MCP joint subluxation due to an incarcerated radial sesamoid.