Locking of the Metacarpophalangeal Joint of the Thumb Caused by a Fracture Fragment of the Radial Condyle of the Metacarpal Head after Dorsal Dislocation

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.

Pathoanatomy and treatment modifications of metacarpophalangeal joint locking of the thumb

Ten patients with metacarpophalangeal joint locking of the thumb were studied. Three of them underwent surgical release. During surgery, it was found that the radial sesamoid was seated in a cartilage defect on the volar aspect of the metacarpal head. It appeared that the defect was created by the proximal edge of sesamoid. When the abductor pollicis brevis and flexor pollicis brevis muscles were partially detached from their insertion at the base of the proximal phalanx, the locking could be successfully released. We hypothesize the mechanism of the metacarpophalangeal joint locking of the thumb in our cases was a hyperextension injury that displaced the radial sesamoid distally and radially. In turn, the sesamoid's pointed proximal edge wore a groove in the cartilage on the metacarpal head, and under abductor pollicis brevis and flexor pollicis brevis tension, the radial sesamoid was locked into the cartilage defect; thereby causing locking of the joint.

SESAMOIDECTOMY AND VOLAR PLATE REPAIR USING SUTURE ANCHOR FOR HYPEREXTENSION INJURY OF THE METACARPOPHALANGEAL JOINT OF THE THUMB

A retrospective study for the combination of suture anchor and selective sesamoidectomy for treating volar instability of the metacarpophalangeal joint (MCPJ) of the thumb. Eleven patients with hyperextension of the MCPJ of the thumb underwent volar plate repair using a volar or voloradial approach. All the patients were reviewed radiologically and clinically using both objective and subjective criteria. The patients presented with sesamoid fractures (n = 2), sesamoid subluxation (n = 1), isolated volar plate laxity (n = 4), isolated sesamoid fracture (n = 4), and metacarpal condyle fracture (n = 2). The inner intersesamoid distance was 4.6 mm and the outer intersesamoid distance was 14.2 mm. The Disabilities of the Arm Shoulder and Hand and Michigan Hand Outcomes Questionnaire scores showed improvement. Volar plate repair using a suture anchor and selective sesamoidectomy is effective with regard to pain relief and stabilisation of volar instability of the thumb.