Copyright 2011
Introduction
Size has many facets and in the context of fractures it has practical application as regards to:
whether the fracture involves cortical surfaces on both sides of the bone (incomplete and complete)
the number of fragments (simple and comminuted)
the length of of separation of two fragments, the distance of displacement and the degree of angulation
the number of sites in a given bone (single segmental)
the number of bones involved (single multiple)
Involvement of Cortical Surfaces – Incomplete vs Complete Fractures
Two broad categories of fracture include those that radiologically appear to be incomplete (a crack in the bone) where through and through cortical bone involvement is not present. This is a common type of fracture in the pediatric population. Complete fractures are seen in both the pediatric and adult population the fracture and is inferred complete if both sides of the cortical bone is fractured. The periosteum is often intact on the compressive side of the fracture line. Examples of complete fractures include, transverse, oblique, spiral, and comminuted fractures.
Examples of incomplete fractures include greenstick fractures, fissure fractures, some types of depression fractures, hairline fractures and stress factures.
The diagram in a shows an incomplete fracture with only one side of the bone being involved. The X-ray of the radius exemplifies the incomplete greenstick fracture in the distal radius (b and overlaid and highlighted in c). A complete fracture through the mid shaft of the radius is diagrammed in c and exemplified in similar manner in d and e.
Courtesy Ashley Davidoff Copyright 2011 103498n01L.8
Hairline Fractures
A hairline fracture is usually an incomplete fracture of bone that is barely visble on plain film examination, with no change in the anatomic alignment. These fractures are often more extensive on CT scan and MRI than anticipated on the plain film, though with normal anatomical alignment aside from immobilization.
The X-Ray shows an incomplete hairline fracture of the right tibia. The fracture on the A-P projection of the right tibia is barely visible and requires manipulation of the image in order to fully appreciate the fracture and its extent barely reaching and involving the lateral (right) cortical margin (b), and further highlighted in (c) with the green arrows pointing to the superior and inferior aspect of the fracture.
Courtesy Ashley Davidoff Copyright 2011 100984c03L.8
Stress Fractures
Another fracture that is commonly incomplete is a stress fracture particularly the stress fractures that occur in the neck of the femur.
The A-P examination of the right tibia and fibula shows an incomplete fracture on the medial edge of the shaft of the fibula and reactive compensatory focal thickening of the cortex on both the medial and lateral edges (highlighted in b). The fracture line is wide with evidence of resorbtion of bone along the edges suggesting subacute fracture. These findings are characteristic of a stress fracture and are an example of an incomplete fracture. Stress fractures occur in high impact athletes such as long distance runners, dancers, particularly en pointe dancers and soldiers after long distance marches.
Courtesy Ashley Davidoff Copyright 2011 29839b01L.8
Simple Fractures – 2 Fragments
This A-P examination of the right hand of a 24 year old male shows a simple oblique fracture of the shaft of the 4th proximal phalanx with near anatomic alignment. The fracture line is overlaid in black in image b. Mild soft tissue swelling is present
Courtesy Ashley Davidoff Copyright 2011 99941.8cL1
Comminuted Fracture
The reconstructed CT scan of the right shoulder in the coronal plane (a) and in 3D (b) exemplifies a comminuted fracture along the weak part of the bone where the shaft (diaphysis) meets the metaphysis (neck). At least 5 fragments can be counted. Associated finding reveals dislocation of the humeral head from the glenoid
Courtesy Philips Medical Systems 88368c.8L
Number of Bones Involved
At the Site of the Force – 2 bones
This set of X-rays in the antero-posterior (A-P) projection shows the difference of the effect of a lateral force on the mid shafts of a pliable pediatric radius and ulna (a) and on the more brittle mature bones of a 19 year patient (b). In the pediatric bones they respond to the force by a bowing deformity without obvious macrofracture. This is a type of greenstick fracture. In the adult the bone shows transverse fracture of the radius and ulna.
Courtesy Ashley Davidoff Copyright 2011 101293.8bc01
Multiple Sites in the Same Bone – Segmental Fracture
A segmental fracture infers that the injury and transmitted forces has resulted in more than one fracture at different sites of the bone. The concern in this injury is interruption of blood supply of the middle fragment preventing normal bone healing and resulting in non union.
The X-ray of the right humerus in A-P projection is from a 76 year old male and shows comminuted spiral fracture segmental consisting of three fragments with a proximal portion (outlined in lime green) middle triangular or butterfly fragment(dark green), and a distal portion (outlined in black). There is reasonable anatomic alignment with excellent bone on bone contact. The fracture was treated with a sling and the follow up 4 months later showed excellent healing. In this case vascular compromise of the diaphysis did not occur.
Courtesy Ashley Davidoff Copyright 2011 103417c03.8s
References
Winquist RA., Hansen, S.T Segmental Fractures of the Femur Treated by Closed Intramedullary Nailing. The Journal of Bone and Joint Surgery Vol 60a No.7 1978