Occipital Condyle Fractures
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Occipital Condyle Fractures (OCFs) were first described by Sir Charles Bell in 1817 during the post-mortem examination of a trauma victim. The occipital condyle-C1 joint provides 25 degrees of combined flexion/extension, 5 degrees of lateral bending, and 5 degrees of axial rotation to each side. It is stabilized by a fibrous capsule that blends into the antero- and posteroatlanto-occipital membranes as well as the Occipito-C1 and C1-C2 ligaments. Following trauma, clinical presentation is non-specific and may include loss of consciousness, neck pain, and lower cranial nerve deficits (may be delayed). Patients may also be neurologically intact.
Classification and Diagnosis
Anderson and Montesano have classified OCFs into three groups:
Type I: usually result from axial force and involve a comminuted OC fracture with little or no displacement into the foramen magnum. Despite ipsalateral alar ligamentous injury, Type I fractures are stable due to intact contralateral alar ligament and tectorial membrane.
Type II: OCF are basilar skull fracture with extension into the condyle. Intact alar ligaments and tectorial membrane maintain stability.
Type III: avulsion of the ipsaleteral condyle by the alar ligament. Condylar fragments may be displaced into the foramen magnum, injuring neural structures. These fractures occur by rotation or lateral bending. Considered unstable.
Tulia's classification is similar but refers only to stability: Type I are stable and non-displaced, Type IIa are stable yet displaced, and Type IIb are unstable and displaced. Instability may be identified on CT or XR by > 8 degrees of axial rotation of O-C1 to one side, > 1 mm of O-C1 translation, > 7 mm of overhand of C1 on C2, > 45 degrees of axial rotation of C1-C2 to one side, > 4 mm of C1-C2 translation, or < 13 mm distance between the posterior body of C2 to the posterior ring of C1. '
Non-displaced, stable fractures do not require immobilization. Displaced, stable OCFs deserve hard collar fixation whereas any unstable fracture will require Halo or surgical fixation.
1. Tuli S, Taor CH, and Mackay M et al. Occipital Condyle Fractures. Neurosurgery. 1997; 41: 368-377.
2. Neeman A and Bloom A. Occipital Condyle Fractures in the Pediatric Population. Radiographics. 2003; 23: 1699-1701.