# Ultrasonographic changes in lower extremity tendon thickness after stroke rehabilitation and their associations with balance and functional outcomes

## TL;DR

This study shows that tendon thickness in the lower extremities of stroke patients increases during rehabilitation and is linked to better balance and function.

## Contribution

The study reveals dynamic changes in tendon thickness during stroke rehabilitation and its association with functional outcomes.

## Key findings

- Paretic-side quadriceps tendon thickness increased significantly after four weeks of rehabilitation.
- Balance and functional outcomes improved alongside tendon thickness changes.
- Quadriceps tendon thickness changes were modestly associated with improvements in balance and independence.

## Abstract

Peripheral musculoskeletal structures may undergo secondary changes after stroke, but tendon-specific adaptations and their relationship with functional recovery are not well defined. This study examined lower extremity tendon thickness in patients with post-stroke hemiplegia before and after a four-week inpatient rehabilitation program and explored associations between tendon thickness and clinical improvement.

In this prospective observational study, 45 patients with post-stroke hemiplegia completed a four-week rehabilitation program. Quadriceps, patellar, Achilles tendon and plantar fascia thicknesses were measured bilaterally at baseline and post-treatment using ultrasonography. Clinical assessments included the Berg Balance Scale (BBS), Functional Ambulation Classification (FAC), Barthel Index, Brunnstrom stages and Modified Ashworth Scale (MAS). Fifteen healthy volunteers served as controls (single assessment). Continuous variables are presented as mean ± SD when approximately normally distributed and as median (IQR) otherwise; p-values were adjusted for multiplicity in secondary analyses as specified.

Paretic-side quadriceps tendon thickness (primary outcome) increased from 5.94 ± 0.96 to 6.48 ± 0.95 mm (p < 0.001), with 21/45 (46.7%) exceeding minimal detectable change with a 95% confidence interval (MDC95). Baseline paretic-side quadriceps thickness was lower than controls (p_adj = 0.048) but did not differ post-treatment (p_adj > 0.99). Patellar and Achilles tendons and plantar fascia also showed consistent bilateral increases (all p < 0.001). Balance and functional outcomes improved over the period (BBS Δ: 6 [4–9]; FAC improved by ≥1 level in 27/45 [60.0%]; Barthel improved with median paired Δ: 0 [0–5]; all p < 0.001). Changes in quadriceps tendon thickness showed modest positive associations with changes in BBS (both sides) and Barthel (non-paretic side).

Lower-extremity tendon morphology in post-stroke hemiplegia appeared dynamic over a 4-week inpatient rehabilitation period, with quadriceps tendon thickness broadly paralleling improvements in balance and functional independence. Larger, longer-term studies are needed to clarify clinical utility.