Fracture pattern characteristics and associated injuries of high-energy, large fragment, partial articular radial head fractures: a preliminary imaging analysis

BACKGROUND: High-energy radial head injuries often present with a large partial articular displaced fragment with any number of surrounding injuries. The objective of the study was to determine the characteristics of large fragment, partial articular radial head fractures and determine any significant correlation with specific injury patterns. MATERIALS AND METHODS: Patients sustaining a radial head fracture from 2002−2010 were screened for participation. Twenty-five patients with documented partial articular radial head fractures were identified and completed the study. Our main outcome measurement was computed tomography (CT)-based analysis of the radial head fracture. The location of the radial head fracture fragment was evaluated from the axial CT scan in relation to the radial tuberosity used as a reference point. The fragment was characterized by location as anteromedial (AM), anterolateral (AL), posteromedial (PM) or posterolateral (PL) with the tuberosity referenced as straight posterior. All measurements were performed by a blinded, third party hand and upper extremity fellowship trained orthopedic surgeon. Fracture pattern, location, and size were then correlated with possible associated injuries obtained from prospective clinical data. RESULTS: The radial head fracture fragments were most commonly within the AL quadrant (16/25; 64 %). Seven fracture fragments were in the AM quadrant and two in the PM quadrant. The fragment size averaged 42.5 % of the articular surface and spanned an average angle of 134.4(°). Significant differences were noted between AM (49.5 %) and AL (40.3 %) fracture fragment size with the AM fragments being larger. Seventeen cases had associated coronoid fractures. Of the total 25 cases, 13 had fracture dislocations while 12 remained reduced following the injury. The rate of dislocation was highest in radial head fractures that involved the AM quadrant (6/7; 85.7 %) compared to the AL quadrant (7/16; 43.7 %). No dislocations were observed with PM fragments. Ten of the 13 (78 %) fracture dislocations had associated lateral collateral ligament (LCL)/medial collateral ligament tear. The most common associated injuries were coronoid fractures (68 %), dislocations (52 %), and LCL tears (44 %). CONCLUSION: The most common location for partial articular radial head fractures is the AL quadrant. The rate of elbow dislocation was highest in fractures involving the AM quadrant. Cases with large fragment, partial articular radial head fractures should undergo a CT scan; if associated with >30 % or >120(°) fracture arc, then the patient should be assessed closely for obvious or occult instability. These are key associations that hopefully greatly aid in the consultation and preoperative planning settings. LEVEL OF EVIDENCE: Diagnostic III.