Comparative Efficacy of Leukocyte-Rich and Leukocyte-Poor PRP for Lateral Epicondylitis on Isokinetic and Isometric Upper Limb Strength under an Identical Rehabilitation Protocol: A Randomized Controlled Trial.

BACKGROUND: Platelet-rich plasma (PRP) therapies are increasingly used to support upper-limb muscle recovery, but the relative effects of leukocyte-poor versus leukocyte-rich PRP (LP-PRP vs. LR-PRP) remain unclear. This study evaluated the temporal and muscle-specific effects of LP-PRP, LR-PRP, and saline injections on upper-limb strength in patients with lateral epicondylitis over 12 months.

METHODS: Seventy-one participants were randomized to LP-PRP, LR-PRP, or saline injections, with the contralateral limb serving as an internal control. The primary outcome was a change in peak isometric wrist extensor torque of the treated limb from baseline to 12 months. Secondary outcomes included isokinetic elbow flexor and extensor torque at 60°/s and 120°/s, isometric wrist flexor torque, hand grip strength, and interlimb comparisons. Secondary outcomes were considered exploratory and interpreted according to statistical significance, multiple-comparison-adjusted p-values, and magnitude of change relative to the predefined MCID threshold.

RESULTS: The primary outcome, peak isometric wrist extensor torque of the treated limb, improved over 12 months in all groups, including PRP and saline groups; however, between-group differences did not exceed the MCID threshold. Exploratory analyses of secondary outcomes suggested differences in the temporal pattern of recovery among selected strength measures, although most between-group differences were modest and did not remain significant after adjustment for multiple comparisons.

CONCLUSION: Both PRP formulations were associated with improvements in peak isometric wrist extensor torque during 12 months of follow-up; however, the primary outcome did not demonstrate clinically meaningful superiority of either PRP formulation compared with saline. Exploratory secondary analyses suggested transient differences in selected strength measures, but these findings should be interpreted cautiously. PRP may serve as an adjunct to structured rehabilitation rather than a determinant of long-term strength recovery.