Posterolateral Rotatory Instability
PLRI - Chronic Elbow Instability
Understanding and treating the most common pattern of elbow instability
Understanding PLRI
Posterolateral rotatory instability (PLRI) was first described by O'Driscoll in 1991. It is characterized by external rotation of the ulna on the humerus coupled with subluxation of the radiocapitellar joint posteriorly.
Key Anatomy
- • LUCL (Lateral Ulnar Collateral Ligament): Primary restraint to PLRI
- • Originates from lateral epicondyle
- • Inserts on supinator crest of ulna
- • Deficiency allows posterolateral subluxation
Symptoms & Diagnosis
Common Symptoms
Clinical Tests
Lateral Pivot Shift Test
Supination and valgus force while extending - clunk as radial head subluxates
Chair Push-Up Test
Patient pushes up from chair arms with forearms supinated - reproduces symptoms
Posterolateral Drawer
External rotation of forearm at 40° flexion - increased laxity vs contralateral
Treatment - LUCL Reconstruction
- • Graft: Palmaris longus (if present), plantaris, or hamstring
- • Humeral fixation: Bone tunnel or docking technique at isometric point
- • Ulnar fixation: Bone tunnel at supinator crest
- • Tensioning: Graft tensioned with elbow at 30° flexion, forearm pronated
- • 0-2 weeks: Splint at 90°
- • 2-6 weeks: Hinged brace, active ROM, avoid supination with extension
- • 6-12 weeks: Progress ROM, light strengthening
- • 3-6 months: Return to activities
Outcome: 85-90% good to excellent results with LUCL reconstruction
Evidence & References
• O'Driscoll SW, et al. Posterolateral rotatory instability of the elbow. JBJS Am 1991
• Sanchez-Sotelo J, et al. Surgical treatment of posterolateral rotatory instability of the elbow. JBJS Br 2005
• Jones KJ, et al. Outcomes of surgical treatment of posterolateral rotatory instability of the elbow. J Bone Joint Surg Am 2012
Last Updated: January 2025 | Content reviewed by Dr. Deepthi Nandan Reddy, FRCS (Ortho)