The "Terrible Tetrad" of the Elbow: A Case Series of Two Patients with a Rare Quadruple-Component Injury and a Proposed New Classification Term.

INTRODUCTION: The "terrible tetrad" of the elbow - simultaneous posterior ulno-humeral dislocation, comminuted radial head fracture with dislocation, coronoid process fracture, and proximal ulnar fracture - is an injury pattern that simultaneously fulfills criteria for both the terrible triad and a Monteggia-type fracture-dislocation. Fewer than fifteen cases have been documented worldwide. We present two cases managed by different surgeons at different institutions and propose the formal adoption of the term "terrible tetrad." CASE REPORT: Case 1: A 50-year-old male painter sustained a right-sided terrible tetrad following a fall from a ladder. Closed reduction failed. Single-stage reconstruction through a posterior approach comprised cementless radial head arthroplasty, ulnar shaft plating, and lateral collateral ligament (LCL) repair. At 5 months, the range of motion was 25-110° with a stable, congruent joint; limited recovery was attributed to rehabilitation non-compliance. Case 2: A 53-year-old woman sustained a left-sided terrible tetrad following a low-energy fall down stairs, with background hypertension and hepatitis C positivity. A combined posterior and lateral two-incision approach was used: Ulnar locking compression plate fixation, coronoid repair with FibreWire and Endobutton, uncemented radial head replacement, and LCL repair with suture anchors. Intraoperative stability and arc of motion were excellent; at 6 weeks, the patient was progressing well with supervised physiotherapy. CONCLUSION: The terrible tetrad is extraordinarily rare and falls outside all existing classification systems. Computed tomography with three-dimensional reconstruction is essential. Systematic single-setting reconstruction - lateral column restored first - is achievable via either a single posterior or combined two-incision approach, depending on injury configuration. Supervised physiotherapy is the principal determinant of outcome.