Acute transverse fracture through the base of the hook of ham ate, with minor separation of the fragments by 2 mm. Features in keeping with a Milch Type I hamatefracture (subtype III (base of hook)).
The most common is subtype 3, as in the case above, which accounts for 75% of hook of ham ate fractures 1. While readily identifiable on CT imaging, the initial modality of plain radiographs can often obscure the diagnosis.
Carpal bones should all be separated by uniform 1-2 mm spacing Radius ulnar tilt 13-30 degrees Radial styloid process projects 8-18 mm Half the late articulates with radius with half over ulna Scaphoid should appear elongated Fracture or ligament disruption will make it appear shortened Scapholunate ligament instability 3 radiographic signs Scapholunate dissociation: Widening of scapholunate joint space >3 mm on PA view (more obvious if clenched fist view) = Terry-Thomas sign Rotary subluxation of scaphoid: Scaphoid appears short on PA with cortical ring sign (circular cortex of bone becomes more prominent due to Palmer tilt) and >60 degree scapholunate angle on lateral view Dorsal intercalated segment instability: Late tilts dorsally due to unopposed extension torque from triquetral and scaphoid tilts more Palmer.
Distal radio ulnar joint disruption Generally seen with intra-articular or distal radial shaft fractures = Gallery fracture -dislocation Often missed due to other fractures taking attention Isolated joint injuries often under-appreciated and missed Ulnar head often dorsally displaced and may appear more prominent Pain with supination/pronation, weak grip PA shows narrowing and overlap of distal RUN Lateral shows solar or dorsal displacement of ulna May require CT Refer for Or tho consult in ED as high recurrence rate and reconstructive rate if missed/not treated adequately Figure 2: Axial CT images at the level of the ham ate shows a nondisplace fracture near the base of the Matebook (arrow).
The Ottawa Ankle Rules, developed by Still, specifies the criteria to be met before ordering X -rays for a patient presenting with an acute ankle injury. Using the diagram below we can determine when an ankle series is required.
Appropriately treat and refer patients Keep costs of health care down Decrease needless imaging Decrease harm to the patient by excess radiation exposure Prevent unnecessary interventions This is just one example of how clinical criteria can help you with your decision to order imaging.
Below, watch Robert Boyle's discuss the different ankle imaging views in a short video from his course, Imaging for Lower Quarter Sports Injuries. Dr. Boyle's is a clinical assistant professor of physical therapy at the University of Puget Sound in the Pacific Northwest.
Dr. Boyle's’ primary area of instruction is orthopedics, which includes evaluation and intervention, manual therapy treatment techniques for the spine and extremities, introduction to joint mobilization, spine manipulation, and clinical radiology. His research interests predominantly include manual physical therapy of the spine and extremities.
References Eichmann LM, Cabernet S, Stereo J, TER Rail G. The accuracy of the Ottawa knee rule to rule out knee fractures: a systematic review. Brand DA, Frazier WH, Kohlberg WC, et al. A protocol for selecting patients with injured extremities who need x -rays.
Can elbow extension be used as a test of clinically significant injury? Hawley C, Greenblatt R. Ottawa and Pittsburgh rules for acute knee injuries.
Comparison of the Canadian C-Spine rule and NEXUS decision instrument in evaluating blunt trauma patients for cervical spine injury. Parties J, Cayman J, Kelly P, Moran CG.
A prospective study of modified Ottawa ankle rules in a military population. Interobserver agreement between physical therapists and orthopedic surgeons.
Still I, Wells G, Alpacas A, et al. Multigenre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. Still IG, Clement CM, McKnight RD, et al.
The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. Still IG, Greenberg GH, McKnight RD, et al. Decision rules for the use of radiography in acute ankle injuries.
Still IG, Greenberg GH, McKnight RD, Wells GA. Ottawa ankle rules for radiography of acute injuries. Still IG, Lesion H, Wells GA, et al.
The Canadian CT Head Rule Study for patients with minor head injury: rationale, objectives, and methodology for phase I (derivation). Still IG, Wells GA, Vandemheen KL, et al.
The Canadian C-spine rule for radiography in alert and stable trauma patients. Tan deter HE, Schwartzman P. Acute knee injuries: use of decision rules for selective radiograph ordering.