“Rule of Spence” and Dickman's Classification of Transverse Atlantal Ligament Injury Revisited

Abstract

Detailed clinical information of 13 adult patients with acute atlantal fractures underwent nonoperative treatment was retrospectively studied. “Rule of Spence” was found inaccurate in predicting either integrity of transverse atlantal ligament (TAL) or atlantoaxial stability, whereas Dickman's classification of TAL injury was more superior to “rule of Spence” on both prediction. Study Design. A retrospective study. Objective. To evaluate the prediction accuracy of “Rule of Spence” and Dickman's classification of the transverse atlantal ligament (TAL) injury on clinical outcomes (mainly focused on atlantoaxial stability) of atlas fractures treated nonoperatively. Summary of Background Data. TAL is regarded as primary stabilizer of the atlantoaxial complex. Atlas fractures are categorized as unstable and stable according to TAL injury or not. “Rule of Spence” and Dickman's classification have been widely used to evaluate the integrity of TAL indirectly or directly. However, there is controversy about how to interpret and apply these image measures appropriately in treatment decision making, and comparing the two measures in same cohort has been lack. Methods. From January 2013 to December 2015, 13 adult patients with atlas fractures, treated nonoperatively at acute posttraumatic phase and followed up for at least 2 years, were enrolled in the study. Lateral mass offset (LMO) and TAL injury were measured by radiography. Atlantoaxial stability, pain in occipital region, limitation of cervical motion, neurological dysfunction, and quality of daily life were evaluated as clinical outcomes. Results. LMO less than 6.9 mm was inaccurate either to exclud TAL injury (4/8, 50% failed) or to predict clinical outcomes (2/8, 25% failed), whereas LMO greater than 6.9 mm was accurate to determine TAL injury (5/5, 100% succeeded) but not to predict atlantoaxial stability (4/5, 80% failed). Two cases with Dickman's classification type I injury (100%) failed to restore C1-2 stability and six of seven type II (85.7%) succeeded. Three patients were indicated for fusion surgery due to instability, and one due to traumatic arthritis. Overall clinical outcomes were satisfactory as pain and quality of life were considered. Conclusion. Dickman‘s classification of TAL injury is of higher superiority to “Rule of Spence” in term of the accuracy of predicting atlantoaxial stability of nonoperatively treated atlas fractures. Level of Evidence: 4

Surgical Versus Conservative Management for Treating Unstable Atlas Fractures: A Multicenter Study

“…37 Liu et al reported that an LMD less than 6.9 mm was inaccurate for excluding TAL injury, whereas an LMD greater than 6.9 mm was accurate for determining the presence of a TAL injury. 5 Using the "rule of Spence," in which an LMD is exceeding 6.9 mm, all TAL injuries were found in the present study.…”

“…Shatsky et al 33 reported that atlas fracture reduction and fixation could be performed irrelevant to the ligament injury type without resulting in C1-C2 instability. Liu et al 5 studied 13 adult patients with atlas fractures who were treated non-operatively at the acute posttraumatic phase and followed up for at least two years. They reported that C1-2 stability failed to be restored in 2 cases with Dickman's classification type I injuries (100%), whereas stability was successfully restored in 6 of 7 type II (85.7%) cases that were treated non-operatively.…”

“…Recent studies have reported that the ''rule of Spence'' was inaccurate for identifying TAL injuries. 4,5,24,34 Using the criterion of an LMD greater than 6.9 mm, approximately 61% to 90.9% of TAL injuries were missed. 6,15,35 Furthermore, Radcliff et al previously reported no correlation between bony displacement and the presence of a TAL injury.…”

“…However, recent studies have shown that existing concepts are inaccurate and should be discarded for predicting TAL integrity or atlantoaxial stability and treatment decisionmaking. 4,5 Dickman classified TAL injuries using magnetic resonance imaging (MRI); a TAL type I injury, characterized by a rupture in the substance of the ligament, should be implemented with early surgery, whereas a TAL type II injury, involving an avulsion fracture at the insertion site of the ligament, has a successful healing rate when treated non-operatively. 6 Various surgical options for treating unstable atlas fractures with favorable outcomes have recently been introduced, such as anterior C1 ring osteosynthesis, C1 open reduction and internal fixation (ORIF), posterior C1-2 fixation, or occipitocervical fusion.…”

Risk Factors for Fracture Nonunion and Transverse Atlantal Ligament Injury After Isolated Atlas Fractures: A Case Series of 97 Patients

“…8,10,11 Historically, lateral mass displacement (LMD) ≥ 7 mm in the setting of an atlas fracture is used to identify patients with TAL injury 12 but may be an imperfect tool to do so. [13][14][15][16] Here, we examined our experience managing isolated atlas fractures at an academic, tertiary referral center, identifying factors associated with MRIconfirmed TAL injury, the rate of fracture nonunion associated with each treatment modality after 12 weeks of follow-up, and selection factors for using one modality vs another.…”