New Diagnostic Method for Hip Problems Using Lasers

Hip problems remain one of the most common orthopedic issues that mostly consist of fracture of the femoral neck (collum) in accidents and femoral head (caput) degeneration. Orthopedic interventions range from osteosynthesis using a nail through the femoral neck, to total hip replacement. An important aspect in judging the outcome of osteosynthesis intervention and the need for a total hip replacement is the status of the caput, where signs of necrosis indicate lack of adequate blood supply through the bone periosteum. Although X-ray and MRI are frequently used in evaluating those kinds of diseases, these methods only focus on the bone itself while neglecting the blood exchange. Accurate diagnostic tools for assessing the clinically important aspects of the hip joint are unfortunately still largely lacking.

Experimental set-up for GASMAS measurements on the femoral head (Source: K. Svanberg et al. / Wiley).

A team of Swedish and Chinese scientists developed a new method to contribute to better diagnostics of necrosis of the caput. The femoral head – the caput – and human bones in general, are normally void of gas-filled pores. The team’s assumption concerning necrosis of human tissue was that gas will develop in the decay process, producing gas-filled pores. This would then also be the case when a femoral head would become necrotic due to, e.g. inadequate blood supply. The bearing idea of the study is that the water vapor in the necrosis-induced pores would be detected by a recently introduced optical detection method – gas in scattering media absorption spectroscopy (GASMAS) – at wavelengths where tissue is translucent. “This GASMAS technique critically takes advantage of the fact that free gases exhibit very sharp optical absorption lines which can be detected by sensitive electronics when superimposed on the much broader absorption structures of the surrounding solid or liquid medium” says Katarina Svanberg of the Center for Optical and Electromagnetic Research in Guangzhou, China.

The outcomes of the measurements of gas in bone samples, four of the samples were affected by caput necrosis, while the remaining six ones were affected by arthritis, seem to confirm the team’s assumptions that degenerated caput contains gas-filled pores. Although the measurements were performed on the human femoral head in vitro, GASMAS could be predicted to be a powerful tool for detection of human femoral head in vivo and thus for the diagnostics of caput necrosis.

In the future work, the team plans to perform the GASMAS measurements intraoperatively in vivo during hip replacement operations. If successful results are obtained, there is the potential for minimally invasive femoral head optical assessment as a diagnostic method to objectively assess the bone status and the need for and type of surgical intervention. The ultimate goal would be to develop a compact and user-friendly device as a tool in orthopedic diagnostic work. Besides this, the methods presented could also have important further diagnostic applications, including the differentiation between viable and necrotic malignant tumor tissue. (Source: COER)

Reference: K. Svanberg et al.: Diagnostics of femoral head status in humans using laser spectroscopy – In vitro studies, J Biophotonics 10 (10), 1355-1363 (2017); DOI: 10.10027jbio.201600229

Link: Center for Optical and Electromagnetic Research, Guangzhou, China

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