Posteriorly Displaced Radial Head Fractures May Represent the Footprint of an Elbow Dislocation or Subluxation as a Variant of Modified Mason Type 4

Document Type : RESEARCH PAPER


1 Harvard Combined Orthopaedic Residency Program, Harvard Medical School, Boston, MA, USA

2 Orthopedics and Traumatology Department, British Hospital, Montevideo, Uruguay

3 Department of Orthopaedic Surgery, Division of Hand and Upper Extremity Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA


Background: The purpose of this case series is to describe surgical decision making and clinical outcomes in posteriorly 
displaced radial head fractures with a major fragment (more than 50% of the head) located behind the humeral condyle. 
We also document the outcome of open reduction and internal fixation of completely displaced radial head fractures.
Methods: A retrospective review of the ICUC® (Integrated Comprehensive Unchanged Complete) database was 
performed between 2012 and 2020. Patients were included if preoperative radiographs demonstrated a major radial 
head fracture fragment located posterior to the humeral condyle and a minimum of 2-year follow-up data was available. 
Results: Ten patients met inclusion criteria. Two patients had an associated elbow dislocation whereas 8 patients did 
not. All patients were found to have disruption of the lateral collateral ligament complex intraoperatively. Nine radial 
head fractures were successfully fixed with interfragmentary screws. One multi-fragmented radial head fracture could 
not be successfully stabilized with interfragmentary screw fixation and was resected. The average time to final followup was 4.8 years (range 2.2-8.1). At final follow-up, 6 patients demonstrated radiographic evidence of a healed radial 
head, 1 patient had avascular necrosis, and 2 had post-traumatic arthritis. None demonstrated radiographic instability. 
The average functional score was 0.64 (SD 0.81) and pain score was 0.45 (SD 0.93). The average elbow extension 
was 8 degrees (SD 11), elbow flexion was 139 degrees (SD 6), forearm supination was 60 degrees (SD 27), and 
forearm pronation was 69 degrees (SD 3).
Conclusion: Recognition of a posteriorly displaced radial head fracture is essential, as it may be an indirect sign of 
elbow instability. This instability should be addressed during surgical intervention. 
Level of evidence: IV


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