FACTSHPI PHYSICAL EXAMIMAGINGA/POccipital Condyle Fractures: clinical decision rule and surgical management (Okonkwo 2009)Citations
Associated pages
AODFACTS
- very rare traumatic fractures
- Anderson and Montesano classifications
- mechanism: high-energy blunt trauma
- Classification systems: Anderson and Montesano (1988), Tuli and colleagues (1997), Hanson et al.
- some will argue these classifications are less relevant than whether there is crani-cervical misalignment and compromise of neural elements [1]
- The bottom line is Anderson/Montesano classifications are useful descriptors at best, and knowing if a Type 3 fracture is present is useful to raise the suspicion of AOD, but ultimately the Measurement of Pang and neural element compression are more important in your operative algorithm (see below).

Anderson / Montesano | Type 1 | Type 2 | Type 3 |
Frequency | 3-13% | 22-54% | 33-75% |
description | impacted / comminuted | basilar skull fracture extending to condyle | avulsion fracture |
mechanism | axial loading of skull onto atlas | direct blow to lower skull | rotation / contralateral bending |
Stability | stable (intact tectorial / contralateral alar) | stable (intact tectorial membrane / alar ligament) | potentially unstable (loading of contralateral alar, tectorial membrane); associated with AOD |
Treatment | Aspen C-collar | Aspen C-collar | rigid immobilization +/- fusion |
IMAGING
CT Cervical spine without contrast
- Calculate the measurements of Pang (condyle-C1 interval)
- Measure 4 equidistant points on sagittal / coronal image on each side (you should be making a total of 16 measurements)
- Combined L Pang = mean of 4 sagittal and 4 coronal measurements on L side
- Combined R Pang = mean of 4 sagittal and 4 coronal measurements on R side
MRI Cervical spine w/o contrast to assess for ligamentous integrity/epidural/subdural hematoma
Occipital Condyle Fractures: clinical decision rule and surgical management (Okonkwo 2009)
- Retrospective review of N = 24745 trauma patients admitted to UPMC 3/2022-4/2008
- 100 patients with 106 occipital condyle fractures (incidence 0.4%)
- Two patients had cranio-cervical misalignment and underwent occipitocervical fusion
- All other patients who survived to discharge received rigid cervical collar or counseling
- No patients developed delayed craniocervical instability or misalignment
- Conclusion:
- focus should be on identifying craniocervical misalignment on CT scans
- Management should be
- occipitocervical fusion / halo fixation in cases demonstrating misalignment
- rigid C-collar with delayed clinical and radiographic evaluation in spine trauma clinic if no misalignment

Citations
[1] Maserati MB, Stephens B, Zohny Z, Lee JY, Kanter AS, Spiro RM, Okonkwo DO. Occipital condyle fractures: clinical decision rule and surgical management. J Neurosurg Spine. 2009 Oct;11(4):388-95. doi: 10.3171/2009.5.SPINE08866. PMID: 19929333.