Ring Avulsion Injuries

Evan H. Horowitz

Michael Guju

Francisco A. Schwartz-Fernandes

INTRODUCTION

Definition
- Acute trauma to a finger caused by a sudden force on a ring, leading to skin and soft tissue damage.¹
- Ring avulsion injuries vary in severity, ranging from bruising to traumatic amputation of the finger.¹
- Such injuries often occur to people who work with machinery while wearing a ring.¹
Incidence and risk factors
- Incidence
  - Wearing a ring or wedding band accounts for 90% of finger avulsion cases that are treated in hospital departments and 13% to 15% of digit amputations per year.²
  - Average ratio of 300 cases per year for a population of 60 million in industrialized countries.²
- Risk factors/epidemiology
  - Young men, average age 31 years at highest risk²
    - Majority of patients of age 21 to 40 years, commonly working men³
  - Occupational hazards involving the use of hands to operate machinery and/or lift heavy objects

CLASSIFICATION OF AVULSION INJURIES

Mechanism
- Ring gets caught and anchored on a heavy, moving object such as a door, fence, or piece of heavy machinery. As the object continues to move, the ring may avulse the underlying tissues.
- Biomechanics (Table 57.2)
  - The average maximum force resulting in class I injuries is 80 N.⁴
  - The average maximum force producing amputation in class III injuries was 154 N. Force measurements for class II injuries were nearly identical to those of class III.⁴
Prognosis
- The extent of artery, vein, and nerve involvement varies and can be used to classify these injuries and determine prognosis.¹,¹⁸
- Recent advancements in microsurgery,⁵ such as revascularization and replantation, have improved prognosis and outcomes.⁶
- Kay et al concluded that extent of skeletal injury is a significant prognostic factor and proposed a revision of the Urbaniak et al classification.⁷

TABLE 57.1 The Urbaniak Classification of Avulsion Injuries and the Kay Classification With adani Modifications¹,⁵,⁷,¹⁴

Urbaniak Classification
I	Avulsion injury with adequate circulation
II	Incomplete avulsion injury with inadequate circulation
III	Avulsion injury with complete degloving or amputation
Kay Classification as Modified by Adani
I	Avulsion injury with adequate circulation
II	Incomplete avulsion injury with inadequate arterial or venous circulation, no skeletal injury IIa Arterial circulation inadequate only IIv Venous circulation inadequate only
III	Incomplete avulsion injury with inadequate arterial or venous circulation, fracture or joint injury present IIIa Arterial circulation inadequate only IIIv Venous circulation inadequate only
IV	Avulsion injury with complete degloving or amputation IVp Complete avulsion injury with amputation proximal to FDS insertion IVd Complete avulsion injury with amputation distal to FDS insertion
FDS, flexor digitorum superficialis.

TABLE 57.2 Tensile Strengths of Rings based on Their Type and Material, and the Common Classes of Injuries Associated With Different Rings²

Type of Ring	Material	Average Tensile Strength (N)	Type of Injuries
Open ring	Nickel-free alloy or silver	21-52.5	Class I injuries
Bejeweled, squared closed, or signet ring	Steel, resin Plexiglas, or Sumac wood	147-203	Class I-III Injuries (at up to 351 N, risk of severe impairment, or class III and IV, is limited to 14% of cases)
Closed, three-strand braided, or signet ring	Jade, aluminum, silver, gold-plate, or steel	624-999	Very high risk of class IV injuries