This post is by Takeru Kataoka, MD of the Shiga Spine Center at Hino Memorial Hospital in Shiga, Japan. Dr. Kataoka is a co-author of a study now in JBJS: Radiographic Measurement of Psoas Muscle Width: A Simple and Reliable Screening Tool for Sarcopenia
As orthopaedic surgeons, we routinely obtain lumbar spine radiographs. We carefully examine them for spinal alignment, instability, degeneration, and deformity. At the same time, the shadow of the psoas muscle is also visible on these images. Could this familiar finding be used to quantitatively assess muscle mass? This simple question became the starting point of our study.
Sarcopenia is increasingly recognized as an important consideration in the care of older patients undergoing orthopaedic surgery. Patients with reduced muscle mass may be at greater risk of postoperative complications and delayed recovery. However, identifying sarcopenia in everyday clinical practice is not always easy. Computed tomography (CT) and magnetic resonance imaging (MRI) provide excellent assessments of muscle quantity and quality, but they are not routinely obtained solely for sarcopenia screening.
The psoas muscle shadow has long been recognized on lumbar radiographs. Because the psoas muscle is an important muscle related to sarcopenia, we wondered whether its width on a radiograph could serve as a simple surrogate marker of muscle mass. Our findings suggest that it may. Read the study.
The key message of our study is not that radiographs should replace CT or other established methods of assessing sarcopenia. Rather, we believe that a simple radiographic measurement could serve as a screening tool, helping to identify patients who may benefit from more detailed assessment. This approach is particularly attractive because lumbar radiographs are widely available and already part of routine evaluation for many patients with lumbar spine disorders.
For us, this study also offers a broader perspective on conventional imaging. Lumbar radiographs are usually obtained to evaluate the spine, but they may contain additional information about a patient’s overall musculoskeletal health. Our next step is to investigate how this simple radiographic measure relates to clinically meaningful outcomes, including postoperative complications, functional recovery, and other indicators of frailty and muscle health. We also believe that artificial intelligence and machine learning may eventually allow more precise assessment of muscle characteristics from radiographs.
As muscle assessment becomes increasingly important in orthopaedics, plain radiography remains one of the oldest and most familiar imaging tools in our daily practice. By looking at this familiar tool from a new perspective, we may discover information that has been there all along.
Takeru Kataoka, MD
Shiga Spine Center, Hino Memorial Hospital, Shiga, Japan
Read the study and access the related video abstract at JBJS.org: Radiographic Measurement of Psoas Muscle Width: A Simple and Reliable Screening Tool for Sarcopenia
Additional perspectives on this study:
Commentary by Geoffrey F. Haft, MD, FAAOS, FAOA: Big Value in the Psoas Shadow
eLetter by Jiayu He and Qian Chen: Radiographic Psoas Muscle Width Is Promising, but Standardization May Determine Its Clinical Utility
