The goal of this observational study is to learn if combining ultrasound and CT scans can better diagnose cartilage fractures in the ribs, and to understand how finding these injuries affects treatment decisions for patients with injuries to the Chest wall.

The main questions it aims to answer are:

• Does using both ultrasound and CT scans find more costal cartilage fractures than CT scans alone?
• Does discovering costal cartilage fractures change how patients are treated, such as whether more patients receive surgery or if different fractures are repaired?
• How do costal cartilage fractures heal, and do they affect lung function, pain, or the risk of complications after surgery?

Patients with cartilage injuries will be followed up at 1, 3, and 12 months after their injury. They will be checked for pain, instability, and healing using ultrasound and sometimes CT scans. The study will also assess lung function, quality of life, and pain levels.

Rib fractures occur in one tenth of patients with traumatic injuries. Our knowledge about the treatment of patients with rib fractures has increased in recent years, as interest in surgical treatment of these fractures has grown. We now know more about the healing process for both surgically and conservatively treated rib fractures than we did before. Fractures in the rib cartilage are less studied. We still know very little about how fractures in the rib cartilage heal and how to approach these fractures during surgical treatment. They are also more difficult to diagnose radiologically than fractures in the bone itself.

Computed tomography (CT) is the best radiological method for diagnosing rib fractures. CT with 3D reconstructions is also a valuable preoperative mapping tool for patients who are to undergo stabilizing surgery for rib fractures. However, CT is not as sensitive for fractures in the rib cartilage, which can therefore be missed. Ultrasound has proven to be more sensitive than CT in identifying fractures in the rib cartilage.

It is unknown whether point of care ultrasound (POCUS) performed by surgeons can identify more cartilage fractures or if this affects the treatment strategy.

The purpose of this study is to investigate whether we can find more rib fractures using POCUS in combination with CT than with CT alone. We also want to study the natural course of rib cartilage fractures using POCUS, CT, and clinical examination. We will also examine whether POCUS changes our plan for treating the patients.

The project is designed as a prospective, comparative study to evaluate a standardized protocol for POCUS for identifying cartilage injuries and for assessing radiological healing of cartilage injuries.

Adult patients treated at the Department of Surgery, Sahlgrenska University Hospital with at least one rib fracture and/or sternum fracture will be asked to participate in the study until the predetermined number of 100 patients is reached.

CT scans of included patients will be reviewed by a radiologist for the presence and extent of fractures of the sternum, cartilage, and ribs, as well as the presence of pneumothorax and/or hemothorax, lung contusion, and lung laceration.

The surgeon reviews the patient's medical record to determine if the patient meets the inclusion criteria. The surgeon then performs POCUS and documents any cartilage injuries. Afterward, the surgeon assesses the CT scan. If the surgeon notes fractures during CT review or POCUS that were not described in the radiologist's report, the CT scan is re-reviewed by the radiologist. If the fractures cannot be found during the re-review, they are considered missed. The surgeon decides during CT review whether there is an indication for surgery according to current guidelines and documents which fractures are planned to be fixed. If cartilage injuries are detected by POCUS, an assessment is made to determine whether the cartilage fractures affect the indication for surgery and/or which fractures are planned to be fixed. During surgery, the injuries that are fixed are documented.

Injuries are graded according to the Abbreviated Injury Scale (AIS), the presence of flail segment, Injury Severity Score (ISS), and New Injury Severity Score (NISS).

Demographic data on included patients are collected: age, sex, height, weight, BMI, smoking status, comorbidities (COPD, asthma, pulmonary emphysema, diabetes mellitus).

Patients with cartilage injuries are followed up at 1, 3, and 12 months after the trauma. The following data are collected at follow-up visits: clinical and radiological healing. Clinical healing means absence of tenderness or palpable and/or perceived instability over the fracture. CT and POCUS are performed after 3 months. If complete radiological healing of the chest wall is lacking, repeat CT and POCUS are performed after 12 months. Radiological healing means signs of healing on CT, divided into groups of complete healing, partial healing, and no healing according to the radiologist's assessment, as well as healing or no healing according to the surgeon's assessment during POCUS.

Other variables collected at follow-up visits are lung function measured by spirometry, quality of life estimated with EQ5D, pain estimated by opioid equivalent consumption, visual analogue scale (VAS), and a graphical representation.

The natural course of fractures in the rib cartilage is incompletely explored. Cartilage fractures can contribute to instability in the chest and are currently usually operated on with the same methods as fractures in the bone itself. Knowledge about healing time and the proportion of cartilage fractures that heal may affect the choice of treatment method and improve the patient's chance of recovery from the injuries.

Inclusion Criteria:

• Trauma patients (≥18 years) treated at the Department of Surgery, Sahlgrenska University Hospital, where CT has shown at least one recent injury to the chest wall.

Exclusion Criteria:

• Patients with injuries resulting from CPR, severe head injury, spinal injury, and neurological or musculoskeletal disease affecting chest mobility will be excluded.

Patients treated at the Department of Surgery, Sahlgrenska University Hospital