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What is the topic of your doctoral research? Why is it important to study the topic?

My work focuses on understanding how the optical behavior of cartilage changes based on its depth within the joint and its overall health or level of degeneration. Studying this topic is important because early detection of cartilage damage is crucial for diagnosing and managing joint diseases like osteoarthritis. Optical techniques offer a non-invasive and real-time way to assess cartilage health. 

By understanding how optical properties vary with tissue depth and integrity, we can improve diagnostic methods, enhance treatment monitoring, and potentially develop new tools for early-stage cartilage evaluation – before irreversible damage occurs.

What are the key findings or observations of your doctoral research?

My research found that the optical properties of articular cartilage – such as light absorption and scattering – significantly vary depending on the depth of the tissue and its structural integrity. Healthy cartilage shows a distinct depth-dependent optical profile, while degenerated or damaged cartilage loses this organized pattern. These changes can be detected using optical imaging techniques, providing insight into the tissue's condition without invasive procedures.

The novelty of my research lies in demonstrating that optical imaging can serve as a sensitive, non-invasive method for detecting early cartilage damage by analyzing depth-specific changes. For the scientific community, this offers a promising direction for improving diagnostic tools for joint diseases like osteoarthritis. 

For the general public, especially patients, this could mean earlier detection, better monitoring of joint health, and more personalized treatment strategies – potentially reducing the need for surgeries or long-term medication.

How can the results of your doctoral research be utilised in practice?

The results of my doctoral research can be used to improve the early diagnosis and monitoring of joint diseases, particularly osteoarthritis. By applying optical imaging techniques – such as near-infrared spectroscopy or optical coherence tomography – clinicians can non-invasively assess the structural integrity of articular cartilage in real time. This means cartilage damage could be detected before it becomes visible through traditional imaging methods like MRI or X-ray.

In the future, these findings could help develop handheld diagnostic tools for orthopedic use or be integrated into arthroscopic procedures to guide treatment decisions more accurately.

What are the key research methods and materials used in your doctoral research?

In my doctoral research, I employed a multidisciplinary approach combining optical imaging techniques, histological analysis, and mechanical testing to explore how the optical properties of articular cartilage vary with tissue depth and integrity. My findings are published across three key papers, each addressing a specific facet of this investigation.

In the first paper, "Articular cartilage optical properties in the near-infrared (NIR) spectral range vary with depth and tissue integrity," I utilized near-infrared spectroscopy (NIRS) to assess how light scattering and absorption in cartilage change with tissue depth and integrity. These techniques enabled a non-invasive study of optical variations that correlate with cartilage health.

The second paper, "Relationship between depth-wise refractive index and biomechanical properties of human articular cartilage," expanded on the NIRS findings by correlating optical data with histological analysis. I used tissue staining techniques to examine the structural changes within cartilage and compared them with the refractive index values obtained from optical measurements, linking these to the tissue's mechanical properties.

In my third paper, "Refractive index of human articular cartilage varies with tissue structure and composition," I incorporated biomechanical testing to further explore how the refractive index correlates with the tissue’s mechanical behavior. I conducted compressive and tensile tests on cartilage samples to understand the functional implications of optical changes, revealing a deeper connection between optical properties and cartilage composition.

The research predominantly used human knee cartilage samples obtained from biobanks. These samples provided real-world data at varying stages of degeneration, crucial for the study of optical properties in both healthy and damaged tissues. I used high-resolution near-infrared spectroscopy (NIRS) device, which was central to analyzing how these optical properties varied with tissue integrity across all three papers. Standard histological tool (e.g., Safranin O) was used to evaluate tissue structure. Additionally, mechanical testing equipment helped assess the biomechanical strength of cartilage, providing a direct link between optical data and tissue functionality, as discussed in Paper 2 and Paper 3. 

These methods allowed for a comprehensive analysis of the interplay between optical properties, tissue integrity, and biomechanical performance, offering valuable insights into the early detection of cartilage degeneration and the potential for non-invasive diagnostic technologies. The results across these three papers collectively highlight the importance of depth-specific optical properties in assessing cartilage health, paving the way for future diagnostic advancements.

The doctoral dissertation of Bilour Khan, MSc (Tech), entitled Articular cartilage optical properties vary with tissue depth and integrity be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus. The opponent will be Professor Alexander Bykau, University of Oulu, and the custos will be Associate Professor Isaac Afara, 91����. Language of the public defence is English.

For more information, please contact: 

Bilour Khan, bilour.khan@uef.fi, tel. +358 50 354 8162

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