Cryostick pre-cooling reduces pain during intra-articular knee injections: a randomized, contralateral-controlled trial.

BACKGROUND

Intra-articular knee injections are essential for osteoarthritis management but often limited by "needle phobia" and procedural pain. The cryostick, a high-thermal-conductivity device, is a potential analgesic; however, evidence regarding its efficacy in reducing pain and bleeding is limited. The purpose of the study was to evaluate whether cryostick application reduces procedural pain, reduces bleeding, and improves patient satisfaction during intra-articular knee injections.

METHODS

This randomized, contralateral-controlled trial included 50 patients (100 knees) with bilateral knee osteoarthritis. One knee received a 20-s cryostick protocol (-20°C) immediately before injection; the contralateral knee received a standard injection. Primary outcome was pain intensity (100-mm VAS) during needle penetration and at 5-min post-injection. Secondary outcomes included bleeding area (mm2) and satisfaction (1-5 Likert scale).

RESULTS

Cryostick application significantly reduced pain during needle penetration (Mean Difference [MD] -24.8 mm; 95% CI -29.9 to -19.7; P < 0.001) and at 5-min post-injection (MD -20.8 mm; 95% CI -26.8 to -14.8; P < 0.001). The Number Needed to Treat (NNT) to achieve the Minimal Clinically Important Difference (13 mm) was 1.28 (95% CI 1.15-1.54) during penetration and 1.79 (95% CI 1.45-2.36) at 5-min post-injection. The bleeding area was significantly smaller with cryostick (MD -4.82 mm2; P = 0.014). Patients reported significantly higher satisfaction scores with the cryostick (4.10 vs 2.96; P < 0.001).

CONCLUSIONS

A 20-s cryostick application is a safe, well-tolerated, and effective adjunct for attenuating pain and bleeding during knee injections. This technically simple approach requires minimal complexity, offering an efficient, non-pharmacological tool to enhance patient comfort.