This prospective, cross-sectional observational study aims to evaluate the differences between joint localizations determined by physicians based on physical examination and joint positions confirmed by musculoskeletal ultrasound. Knee, elbow, ankle, and wrist joints will be assessed in volunteer physicians working in Physical Medicine and Rehabilitation and Orthopedics and Traumatology.

For each joint, participants will identify the joint space based on physical examination and the marked locations will be compared with ultrasound-confirmed joint positions. The distance between clinically determined and ultrasound-confirmed locations will be measured in millimeters. The study seeks to provide objective data on the accuracy of clinical joint localization and to support educational approaches in clinical anatomy and musculoskeletal examination training.

This study is designed as a prospective, cross-sectional, observational comparison of clinical joint localization and ultrasound-confirmed joint positioning. The study will be conducted at Bursa City Hospital and will include volunteer physicians working as residents or specialists in Physical Medicine and Rehabilitation or Orthopedics and Traumatology.

Participants will be asked to localize the joint space of the knee (tibiofemoral), elbow (humeroulnar), ankle (tibiotalar), and wrist (radiocarpal) based on physical examination in standardized positions. Clinically determined joint locations will be marked on the skin using a removable marker.

Following clinical marking, musculoskeletal ultrasound examinations will be performed by an experienced investigator using a high-frequency linear transducer. Ultrasound-confirmed joint positions will be identified according to standardized scanning protocols. The investigator performing the ultrasound assessment will be blinded to the participant's specialty and level of experience.

The primary outcome measure will be the distance, measured in millimeters, between the clinically marked joint location and the ultrasound-confirmed joint position. Secondary analyses will evaluate differences in localization accuracy among different joints and between physicians with different levels of clinical experience.

The study involves no therapeutic or diagnostic intervention and poses minimal risk to participants. All data will be collected anonymously and analyzed at the group level. The results are expected to contribute to a better understanding of the limitations of physical examination-based joint localization and to inform educational strategies incorporating ultrasound in clinical anatomy training.

Inclusion Criteria:

• Physicians working as residents or specialists in Physical Medicine and Rehabilitation or Orthopedics and Traumatology
• Age 18 years or older
• Voluntary participation with written informed consent
• Ability to perform physical examination-based joint localization

Exclusion Criteria:

• Refusal to participate or provide written informed consent
• Any condition preventing completion of physical examination procedures
• Non-compliance with the study protocol

The study population consists of adult physician volunteers recruited from a tertiary care hospital. Participants are licensed medical doctors who participate as reference subjects for joint localization. Each participant is asked to indicate the anatomical location of selected joints (knee, elbow, ankle, and wrist), which is subsequently assessed by physical examination and confirmed using ultrasound imaging within the scope of this observational study.