BACKGROUND: The aspiration of the accompanying haematoma by Mason type I radial head fractures is advocated by several authors to achieve an analgesic effect. The purpose of this study was to investigate the effect of haematoma aspiration on intra-articular pressure and on pain relief after Mason I radial head fractures.MATERIALS AND METHODS: A total of 16 patients (10 men and six women, age 23-47 years) with an isolated Mason I radial head fracture were subjected to haematoma paracentesis. Initially, intra-articular pressure was measured by using the Stryker Intra-Compartmental Pressure Monitor System. After haematoma aspiration, a new pressure measurement without moving the needle was performed. Pain before and after haematoma aspiration was evaluated by using an analogue 10-point pain scale.RESULTS: Intra-articular elbow pressure prior to haematoma aspiration varied from 49 to 120 mmHg (median, 76.5 mmHg), while following aspiration, it ranged from 9 to 25 mmHg (median, 17 mmHg). The median quantity of the aspired blood was 2.75 ml (range, 0.5-8.5 ml). Patients reported a decrease in the visual analogue score (VAS) for pain from 5.5 (4-8) before to 2.5 (1-4) after aspiration. Decrease for both pressure and pain was statistically significant (p=0.005).CONCLUSION: The formation of an intra-articular haematoma in the elbow joint following an undisplaced Mason I radial head fracture leads to a pronounced increase of the intra-articular pressure accompanied by intense pain for the patient. The aspiration of the haematoma results in an acute pressure decrease and an immediate patient relief.