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Case Report  |   March 2018
Nontraumatic First Rib Fracture and Empyema Presenting as Shoulder Pain
Author Notes
  • From the UnityPoint Clinic in Grundy Center, Iowa (Dr Neverman), and the University of Missouri School of Medicine in Columbia (Dr Clary). 
  • Financial Disclosures: None reported. 
  • Support: None reported. 
  •  *Address correspondence to Eric M. Neverman, DO, MHA, UnityPoint Clinic, 101 East J Ave, Suite 120, Grundy Center, IA 50638-2006. Email: eric.neverman@unitypoint.org
     
Article Information
Emergency Medicine / Pain Management/Palliative Care
Case Report   |   March 2018
Nontraumatic First Rib Fracture and Empyema Presenting as Shoulder Pain
The Journal of the American Osteopathic Association, March 2018, Vol. 118, e12-e14. doi:https://doi.org/10.7556/jaoa.2018.040
The Journal of the American Osteopathic Association, March 2018, Vol. 118, e12-e14. doi:https://doi.org/10.7556/jaoa.2018.040
Abstract

Fracture of the first rib is rare because of the anatomic protection provided by surrounding structures. Osseous fatigue caused by repetitive motion and antagonistic muscular contraction is postulated to contribute to nontraumatic first rib fracture, which is most often described in adolescent athletes in sports that involve repetitive overhead motion of the arm. In this report, we describe a 49-year-old man with an occupation involving repetitive overhead motion at the shoulder who was found to have a nontraumatic first rib fracture. The condition resolved with treatment.

Fracture of the first rib is uncommon because of the anatomical protection provided by overlying soft tissue and bone.1 First rib fracture may be a hallmark of severe injury in trauma patients, and it can alert clinicians to associated chest, cardiac, and abdominal organ injury, as well as injury to surrounding vascular and neurologic structures, such as the subclavian artery and brachial plexus.2 However, isolated fracture of the first rib has also been more recently described in cases of minor trauma, such as falls,1,3 and nontraumatic fracture of the first rib has been reported in adolescents who participate in sports that involve repetitive overhead motion of the arm, including weight-lifting,4 swimming,5 lacrosse,6 baseball,7-9 football, and tennis.7 Similarly, nontraumatic first rib fracture has been reported in patients whose occupations require repetitive overhead use of power tools.10 In these cases,4-10 repetitive muscular contraction is thought to contribute to osseous fatigue, which eventually results in the fracture. The current report describes a first rib fracture in a 49-year-old man that was complicated by development of a hematoma and empyema proximate to the fracture. 
Report of Case
A 49-year-old man presented to the emergency department with progressively worsening left shoulder pain for the past 4 days. He first noted the pain while repetitively handling packages, which was a central task in his occupation. At the time of presentation, he described sharp left anterior shoulder pain that radiated to the left upper chest, lower neck, and upper arm. He reported that the pain was a 10 out of 10 on a 10-point scale (1 being the least pain and 10 being the most), despite taking nonsteroidal anti-inflammatory drugs. The patient was evaluated at another emergency department 4 days prior after presenting with left shoulder pain, at which time results of electrocardiography and serial troponin levels were normal. At the current presentation, a radiograph of the patient's left shoulder was unremarkable, and a magnetic resonance image of the left shoulder demonstrated no evidence of musculoskeletal abnormality, abscess, or myositis. His medical and surgical histories were noncontributory. Findings from a complete review of systems were otherwise negative. 
The patient's vital signs were as follows: temperature, 38.3°C; blood pressure, 106/62 mm Hg; respiration rate, 12/min; and oxygen saturation while breathing room air, 94%. Musculoskeletal examination revealed restricted active left shoulder abduction at 90° because of pain. There was point tenderness in the left supraclavicular fossa and boggy tissue of the left infra- and supraclavicular fossae. Results of a neurovascular examination of the bilateral upper extremities was normal. The patient reported that he rarely consumed alcohol, he denied use of tobacco products or illicit substances, and had no recent travel. He had several small, healing abrasions on his hands and arms that he attributed to rough-housing with his dogs. 
Results of laboratory tests revealed a white blood cell count of 12.0 K/µL, with 69% neutrophils and 23% bands; an erythrocyte sedimentation rate of 42 mm/h; and a C-reactive protein level of 11.0 mg/dL. A single-view radiograph of the chest was unremarkable. The patient was admitted to the hospital for clinical observation and pain management. On the day of admittance, blood culture results were positive for methicillin-sensitive Staphylococcus aureus, and the patient was given vancomycin intravenously. A computed tomographic image of his chest showed a left nondisplaced first rib fracture with a small hematoma proximate to a 9-cm left upper lobe fluid collection (Figure). 
Figure.
A computed tomographic image of the chest of a man presenting with progressively worsening left shoulder pain showed a left nondisplaced first rib fracture with a small hematoma proximate to a 9-cm left upper lobe fluid collection.
Figure.
A computed tomographic image of the chest of a man presenting with progressively worsening left shoulder pain showed a left nondisplaced first rib fracture with a small hematoma proximate to a 9-cm left upper lobe fluid collection.
A pigtail catheter was placed by an interventional radiologist on hospital day 3 for drainage of the fluid, and purulent material was collected. The culture was identified as methicillin-sensitive Staphylococcus aureus. A peripherally inserted central catheter was placed the same day, after clearance of bacteremia, and the treatment was transitioned from vancomycin to a continuous infusion of nafcillin, 12 g/d. Additional investigations included transesophageal echocardiography, which did not demonstrate valvular vegetations concerning for endocarditis. After removal of the pigtail catheter on hospital day 7, the patient was discharged home with a continuous nafcillin infusion pump to complete 6 weeks of antibiotic therapy. A follow-up computed tomographic image taken after the completion of antibiotic therapy revealed resolution of the empyema. The patient made a complete recovery, with return to his activities of daily living. 
Discussion
The first rib is the broadest and shortest of the 12 ribs. It attaches to the manubrium through the costal cartilage anteriorly and attaches to the first thoracic vertebral body posteriorly. The first rib contains 2 grooves on the superior surface for the subclavian vessels that are separated by the scalene tubercle, which serves as the point of attachment for the anterior scalene muscle. Additional muscles attached to the first rib are the medial scalene, serratus anterior, and intercostal muscles. The subclavian vein courses anteriorly to the scalene tubercle, whereas the subclavian artery is positioned posteriorly. The groove for the subclavian artery is the most narrow portion of the bone and is often the site of stress fracture in cases of repetitive muscular contraction, resulting in shearing force at the location.4 
In a nontraumatic fracture of the first rib, sudden muscular loading or repetitive muscle use that involves opposing forces contributes to osseous fatigue and may lead to fracture.4,6,10 The patient in the current case was found to have a first rib fracture that was associated with a small hematoma and development of an empyema. The patient's occupation primarily consisted of handling packages in a warehouse and involved repetitive overhead motion of the upper extremities, which may have caused osseous fatigue that could, in turn, have caused the fracture. Although empyema is a common complication of retained hemothorax in traumatic chest wall injury,11 the development of an empyema associated with a nontraumatic rib fracture was an unusual feature. We postulate that the hematogenous spread of Staphylococcus aureus occurred after a low-grade bacteremia, perhaps caused by the superficial abrasions on the patient's hands. An alternative explanation could be a primary osteomyelitis with secondary extension to surrounding tissues, but bacterial osteomyelitis of the ribs is very rare and typically identified in children and young adults.12,13 
Management of isolated nontraumatic first rib fracture is typically conservative and includes pain management, activity modification, and gradual return to activities, with most patients making a complete recovery. Patients initially may need to rest the affected limb and gradually return to activity when symptoms cease, which often occurs 4 to 8 weeks after the injury.3,6,9 A complication associated with a stress fracture is progression to a complete fracture with nonunion, which can require 6 to 12 months of restricted activity.9 
Conclusion
Fracture of the first rib is rare but can be caused by repetitive overhead motion of the upper extremities, which likely contributed to osseous fatigue in this patient. This mechanism of nontraumatic injury is usually described in adolescents in throwing and rowing sports and is typically not associated with complications, making the patient's age and development of empyema in the current case particularly noteworthy. 
References
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Figure.
A computed tomographic image of the chest of a man presenting with progressively worsening left shoulder pain showed a left nondisplaced first rib fracture with a small hematoma proximate to a 9-cm left upper lobe fluid collection.
Figure.
A computed tomographic image of the chest of a man presenting with progressively worsening left shoulder pain showed a left nondisplaced first rib fracture with a small hematoma proximate to a 9-cm left upper lobe fluid collection.