Why is a ray amputation called a ray?

What is Ray Amputation and Why is it Called "Ray"?

A ray amputation is the surgical removal of an entire digit (finger or toe) along with its corresponding metacarpal or metatarsal bone, and it is called a "ray" because the anatomical unit of a digit plus its metacarpal/metatarsal bone resembles a radiating ray extending from the hand or foot. 1, 2

Anatomical Basis of the Term

The term "ray" refers to the anatomical concept where each digit and its associated metacarpal bone form a distinct longitudinal unit that radiates outward from the carpus (wrist bones) or tarsus (ankle bones), similar to rays of light emanating from a central point. 1, 2

• Each hand has five rays: the thumb ray (first ray), index finger ray (second ray), middle finger ray (third ray), ring finger ray (fourth ray), and small finger ray (fifth ray). 3, 4
• The ray includes the entire digit (all phalanges) plus the metacarpal bone, extending proximally to the carpometacarpal joint. 1, 2

What the Procedure Involves

Ray amputation removes the entire functional and skeletal unit rather than just amputating through the digit itself. 2, 5

• The procedure was pioneered by Bunnell in the 1920s and initially performed as a salvage procedure for proximal interphalangeal joint dysfunction. 2
• Modern technique involves amputation at the proximal metacarpal metadiaphyseal flare with concomitant closing wedge osteotomy to allow superior gap closure between residual fingers. 1
• The goal is to make the space between resulting fingers as close to normal as possible while maintaining the structure of the carpus and alignment of the hand. 1

Clinical Indications

Ray resection is indicated when preservation of a functional digit is unattainable or when the presence of an abnormal, unreconstructable digit interferes with overall hand function. 2

Specific indications include:

• Vascular insufficiency requiring tissue removal. 6, 2
• Tumors (aggressive benign or malignant) of the hand where digit preservation is not feasible. 2, 5
• Severe infection, particularly in diabetic foot infections where partial ray amputation may be performed to avoid more extensive amputation. 6
• Trauma with irreparable damage to the digit and metacarpal. 2, 3
• Recurrent Dupuytren contracture. 2
• Congenital abnormalities of the hand. 2

Functional and Aesthetic Outcomes

Compared with amputation at the proximal phalangeal level, single ray resection has better cosmesis and similar function, resulting in improved patient satisfaction. 2

• A 15% to 30% loss in grip and pinch strength has been reported following ray amputation. 2
• Functional assessment using the Musculoskeletal Tumor Society staging system shows an average score of 27.5 out of 30. 5
• Grip strength averages 66% of the contralateral side (range 38%-100%). 5
• Function can be compromised by perioperative radiotherapy. 5

Special Considerations for Central Ray Resections

Central ray resections (middle or ring finger) present unique technical challenges because insufficient closure of the gap between metacarpals can produce an enlarged space between remaining digits and potentially cause digital malrotation, both negatively affecting hand function. 1

• Ray transposition techniques may be employed, where the fifth ray is transposed to the fourth ray position following ring finger amputation. 3, 4
• Osteotomy-based transpositions can be performed at the metacarpal level or through intracarpal wedge-osteotomy of the hamate. 3