Development of a pilot study protocol for evaluating wound healing and early prosthetic rehabilitation in primary unilateral transtibial amputees

BACKGROUND:
Timely prosthetic fitting after amputation is crucial for lower limb amputees' mobility and quality of life, yet readiness assessments lack standardization and objectivity [1]. Clinical judgment is inconsistent, relying on superficial evaluations of residuum healing. Disagreements persist over optimal post-amputation practices, such as rigid vs. soft dressings [2] and casting techniques for prosthetic sockets [3]. To address these challenges, objective measures like biomarkers are needed to improve healing assessments and prosthetic readiness evaluations.

AIM:
This project aimed to develop outcome measurement techniques for a pilot study protocol to assess the acceptability of various measures, including biomarkers, for monitoring surgical site wound healing and early prosthetic rehabilitation. The study will follow a cohort of primary unilateral vascular transtibial amputees undergoing six standard care pathways, including rigid versus soft dressings and hands-on versus hands-off casting techniques.

METHOD:
Over 20 outcome measures were identified, including residuum volume and shape, oxygen saturation, wound temperature and colour, and healing biomarkers. MATLAB 2024a scripts (MathWorks Inc., California, USA, 1984) were validated against CloudCompare (CloudCompare 2.13.2, 2024) using cylinder, sphere, and residual limb 3D stereolithography (STL) files, analysing shape (mesh-to-mesh Euclidean distance) and volume differences between STLs. A commercially available sleep monitoring ring's efficacy as a continuous oxygen saturation monitor was evaluated against three medically certified devices through Bland-Altman and Spearman’s Rank correlation analyses. MATLAB scripts were used to realign thermal infrared and normal camera images of limbs over time, visualizing temperature and colour changes. Initial testing of ELISA (Enzyme-Linked Immunosorbent Assay) and wound blotting techniques [4] for assessing systemic and local levels of healing biomarkers was performed.

RESULTS:
MATLAB and CloudCompare produced similar root mean square errors when comparing shape and volume differences between spheres and cylinders. The Go2Sleep ring showed poor correlation with medical devices, failing to meet the required strong Spearman’s Rank correlation coefficient (0.90–1.00, p ≤ 0.05) and a maximum 3% Bland-Altman mean bias. The MATLAB scripts effectively visualized temperature changes, and initial testing of a sandwich ELISA test for localized fluorescence detection of the inflammation biomarker C-Reactive Protein (CRP) was conducted.

DISCUSSION AND CONCLUSION:
The development of this pilot study explores advanced technologies for assessing residual limbs post-amputation and during early prosthetic rehabilitation. Techniques like laser limb scanning, pulse oximetry, infrared thermal imaging, and ELISA assays show potential to improve wound healing assessment accuracy. Challenges like biomarker variability and assay optimization are addressed, laying the groundwork for refining outcome measure methodologies to enhance patient care post-limb loss.

REFERENCES:
[1]: Day JD; 2023, Prosthet Orthot Int.
[2]: Kwah LK; 2019, Cochrane Database Syst Rev.
[3]: Safari MR; 2013, Sci World J.
[4]: Minematsu T; 2013, Wound Repair Regen.