Long-term sensory and functional recovery in innervated radial artery superficial palmar branch flaps: a retrospective cohort study of durable tactile gnosis in digital reconstruction

Purpose: The innervated radial artery superficial palmar branch (iRASP) flap incorporates the palmar cutaneous branch of the median nerve (PCMN), enabling sensory recovery after digital reconstruction. This study evaluated 10-year longitudinal sensory and functional outcomes after iRASP flap reconstruction.Methods: A retrospective analysis of 45 iRASP procedures (2014–2024) was conducted. Outcomes were assessed from the early postoperative period (<3 months) to long-term follow-up (10 years) using the Semmes-Weinstein monofilament test (SWMT), static and moving two-point discrimination (S2PD and M2PD), grip strength, and the Jebsen-Taylor Hand Function Test (JHFT). The effects of age, PCMN pattern, neurorrhaphy technique, and flap revision were analyzed. Two analysis cohorts were defined by data completeness: a sensory cohort (n=20) and a functional cohort (n=23).Results: All outcomes improved over 10 years. Early “poor” sensory grades improved to “good” or “excellent” in 50% of patients by 12 months. Longitudinal analysis showed that SWMT scores peaked at 1–2 years, whereas S2PD and M2PD reached stable “good/excellent” levels by 3–5 years. M2PD continued to improve at 6–10 years (p<0.05). Grip strength showed the greatest long-term improvement, reaching an “excellent” grade by 6–10 years (p=0.046). JHFT scores stabilized early and remained consistent during follow-up. Clinical and surgical factors did not significantly affect final sensory outcomes (p>0.05).Conclusion: The iRASP flap supported sensory and functional maturation for up to 10 years after digital reconstruction. Coordination stabilized relatively early, whereas discriminative sensation and motor strength continued to improve over time, supporting gradual restoration of tactile gnosis. The iRASP flap may provide durable sensory and functional recovery in palmar digital reconstruction.