A Novel Approach to Open Reduction and Internal Fixation of Distal Radius Fractures Utilizing a Multi-Degree-of-Freedom Traction and Stabilization Device

Abstract

Open reduction and internal fixation (ORIF) is a surgical procedure performed with the objectives of restoring normal alignment and providing stability to broken bone fragments after a fracture. This procedure is increasingly used to treat fractures of the distal end of the radius. Reduction is achieved by the surgeon pulling and manipulating the hand while looking at real-time X-rays, and frequently requires large forces to distract impacted fragments from the proximal bone. This study presents the design and preliminary testing of a multi-degree-of-freedom (DOF) device capable of performing both distraction and reduction of fractured bone fragments using a traction splint mechanism with locking ball joints. A prototype was manufactured, and tests were conducted by a practicing hand surgeon. Both qualitative and quantitative tests using a phantom arm were performed. Quantitative force testing found an 80% reduction in the maximum force required to create needed traction, while qualitative tests with a hand surgeon found the device's ability to reduce and stabilize bone fragments while the hardware is secured to be more intuitive and less obstructive than existing techniques.

Fig. 1

Volar plate. These come in a variety of shapes and sizes to conform to the wrist of the patient and do not need to be removed following surgery.

Fig. 2

Displaced (a) and (b) versus nondisplaced, (c) fractures

Fig. 3

K-wires are drilled in to stabilize the bone fragments while the volar plate is screwed in position

Fig. 4

Range of motion requirements: 90 deg dorsal-volar angulation, 60 deg side-to-side rotation, 3 cm forward-backward translation, 2 cm side-to-side translation, 2 cm up-down translation

Fig. 5

Design overview. The device utilizes a ratchet-based traction strap in combination with two coupled, locking ball joints to enable free manipulation of the hand in multiple degrees-of-freedom. Each component is explained in further detail in the sections that follow.

Fig. 6

Forces and moments in the system

Fig. 7

Proof-of-concept prototype

Fig. 8

Detailed use case in ORIF surgery of distal radius: (1) patient's forearm is strapped down, (2) wrist support is adjusted and moved into position, (3) ball joint carriage is adjusted and moved into position, (4) traction strap is installed, (5) hand is splinted to backing plate (Not shown: An incision is made on the volar side of the patient's wrist, revealing the fracture site where the hardware is to be installed.) (6) impacted bone fragments are distracted by pulling traction using the device's ratchet mechanism. Once fragments are distracted, tension can be momentarily released. (7) The surgeon manipulates the hand through multiple DOFs in order to reduce the fragments into their correct position. For example, the surgeon may place the wrist in flexion as shown here. Once the fragments are reduced, ball joints can be locked, securing the position of the hand. Traction can be reapplied, and the ball joint carriage locked in place for additional stabilization. (8) Hardware is screwed into place and the incision is closed (not shown).

Fig. 9

Design of custom ball joint