Ultrasound Evidence of Fibrillar and Thickness Changes in Plantar Fasciosis Following 20% Dextrose Prolotherapy: Perifascial vs. Intrafascial Injection During a 1-Year Follow-Up

Introduction: Plantar fasciosis is a common degenerative condition characterized by structural alterations of the plantar aponeurosis, including increased thickness and loss of its normal fibrillar pattern. Ultrasound imaging is widely used to assess these changes; however, the validity of plantar aponeurosis thickness as a marker of tissue recovery remains controversial. Dextrose prolotherapy has been proposed as an effective treatment for this condition, although its effects are not yet fully established. In particular, different injection approaches have been described, such as perifascial and intrafascial techniques, whose comparative effectiveness remains unclear. Therefore, the aim of this study was to evaluate longitudinal changes in plantar aponeurosis thickness and fibrillar pattern following treatment with these two prolotherapy approaches. Methods: A total of 56 patients with plantar fasciosis were prospectively evaluated over a one-year period following treatment with 20% dextrose prolotherapy. Ultrasound assessments were performed at multiple time points to measure plantar aponeurosis thickness and to qualitatively evaluate the fibrillar pattern (recovered vs. non-recovered). Longitudinal changes in thickness were analyzed using repeated-measures generalized linear models (GLMs), while differences in fibrillar pattern recovery according to injection technique (intrafascial vs. perifascial) were assessed using the chi-square test and Fisher’s exact test. Results: No significant changes in plantar aponeurosis thickness were observed over the follow-up period (p = 0.260), despite a slight decreasing trend. In contrast, recovery of the fibrillar pattern was observed in 92.9% of patients (52/56) at one year. The recovery rate was significantly higher in the perifascial group (100%) compared to the intrafascial group (80%) (Fisher’s exact test, p = 0.013). Qualitative fibrillar pattern assessment was independently re-evaluated by a blinded second examiner, demonstrating almost perfect inter-rater agreement (Cohen’s κ = 0.83). Conclusions: Dextrose prolotherapy was associated with ultrasonographic evidence of structural tissue remodeling of the plantar aponeurosis, as evidenced by recovery of the fibrillar pattern, without inducing significant changes in thickness. These findings suggest that assessment of the fibrillar pattern may offer additional information regarding structural remodeling following 20% dextrose prolotherapy, whereas plantar aponeurosis thickness remained relatively stable throughout follow-up.