Working Diagnosis:
First Rib Stress Fracture

Treatment:
Initially the patient was treated conservatively with 4 weeks of rest and no gymnastics. At the 4 week follow up she endorsed improved symptoms but was still having moderate pain despite rest. She was prescribed Vitamin D and calcium supplementation and allowed to resume non-weighted lower body strengthening exercises. At her 8 week follow up she was still having pain and repeat x-rays showed NO significant interval healing. Chest CT was ordered given concern for malunion or delayed union which showed a nondisplaced subacute appearing right lateral 1st rib fracture with callus formation around the fracture but no significant bony bridging Case Photo #2 . At this time the patient was referred to cardiothoracic surgery who ordered a repeat CT scan of the chest 2 months later due to persistent pain and development of thoracic outlet syndrome. This scan again showed similar findings with nonunion of the first rib fracture Case Photo #3 .

Outcome:
Patient underwent a right first rib resection approximately 8 months after her initial symptom onset.Patient is still pending return to gymnastics at this time as she undergoes physical therapy to regain strength.

Author's Comments:
Upper extremity stress fractures are uncommon, with rib stress fractures being exceedingly rare, and mostly described in the literature as individual case reports or small series (1,4). When they do occur, the first rib is the most common site. The first published case report of a first rib stress fracture in a gymnast with non-union was noted in 1991 (3), and the literature remains scarce since. Risk factors include: amenorrhea, osteopenia/ osteoporosis,extreme overuse, repetitive use, and severe coughing paroxysms. Injury occurs as stress is placed on the rib during repetitive contraction of attached muscle accentuated during training because muscles strengthen more rapidly than bone. The first rib is susceptible to stress injuries and fracture because a groove for the subclavian artery is a site of weakness due to superiorly directed forces from the scalene muscles and inferiorly directed forces from the serratus anterior and intercostal muscles (5). Three main types of first rib stress fractures exist and a CT scan classification system has been proposed (2). Potential late complications of first-rib stress fracture are rare, but include brachial plexus palsy, thoracic outlet syndrome, and Horner syndrome; all of which can result from extensive callus formation (5). All attempts at conservative management should be attempted, however if an athlete is unable to return to sport pain free, surgical consultation should be explored for rib resection.

Editor's Comments:
The author has done an excellent job reviewing rib stress fractures and the rarity of the condition. Like most lower extremity stress fractures, repetitive stresses in the upper extremity cause accelerated bone remodeling and when it supersedes the healing capabilities a stress fracture will occur. Uniquely though, 1st rib stress fractures are thought to be resulting from excessive muscular force along with inherent weakness of the 1st rib at the groove for the subclavian artery (7), though muscular imbalances have also been proposed as an etiology especially during times of rapid strength training (6). These fractures have been documented in many sports which require repetitive shoulder motion ranging from rowing, volleyball, football, squash, tennis, lacrosse, gymnastics, ballet, aerobics, and weightlifting (6). Presentation usually involves insidious pain in the posterior shoulder, under the scapula, or posterior to the clavicle which can lead to a delay in the diagnosis if the pain is thought to be due to an ipsilateral shoulder complaint. The diagnosis is difficult clinical and usually relies on characteristic findings on MRI imaging studies as plain films can be unreliable (6), though characteristic findings on cervical plain films can also be used (8). As the author mentioned, management is usually conservative with activity modification, correction of muscular imbalances, and considering a metabolic bone workup if there is no response. If excessive callus formation leads to compressive symptomatology or if the patient remains symptomatic with a non-union at 6 months then surgical intervention is warranted (6,8)

References:
1) Connolly, Leonard P., MD; Connolly, Susan A., MD. Rib Stress Fractures. Clinical Nuclear Medicine. Oct 2004 Volume 29 (10) 614-616.
2) Kawashima K, Terabayashi N, Asano H, Akiyama H. Classification of stress fractures of the first rib in adolescent athletes. J Pediatr Orthop B. 2020 Jul;29(4):409-411. doi: 10.1097/BPB.0000000000000720. PMID: 32044858.
3) Proffer DS, Patton JJ, Jackson DW. Nonunion of a first rib fracture in a gymnast. Am J Sports Med. 1991 Mar-Apr;19(2):198-201. doi: 10.1177/036354659101900218. PMID: 2039074.
4) Rodney J. Stanley, T. Bradley Edwards. Management of Proximal Humeral and First Rib Stress Fractures. Operative Techniques in Sports Medicine. 2006 Volume 14(4) 270-274, ISSN 1060-1872, https://doi.org/10.1053/j.otsm.2006.05.004.
5) Wild AT, Begly JP, Garzon-Muvdi J, Desai P, McFarland EG. First-rib stress fracture in a high-school lacrosse player: a case report and short clinical review. Sports Health. 2011 Nov;3(6):547-9. doi: 10.1177/1941738111416189. PMID: 23016057; PMCID: PMC3445230.
6) Chaudhury S, Hobart SJ, Rodeo SA. Bilateral first rib stress fractures in a female swimmer: a case report. J Shoulder Elbow Surg. 2012 Mar;21(3):e6-10. doi: 10.1016/j.jse.2011.08.048. Epub 2011 Nov 6. PMID: 22056323.
7) O'neal M, Ganey TM, Ogden JA. First rib stress fracture and pseudarthrosis in the adolescent athlete: the role of costosternal anatomy. Clin J Sport Med. 2009 Jan;19(1):65-7. doi: 10.1097/JSM.0b013e3181919495. PMID: 19124986.
8) Funakoshi T, Furushima K, Kusano H, Itoh Y, Miyamoto A, Horiuchi Y, Sugawara M, Itoh Y. First-Rib Stress Fracture in Overhead Throwing Athletes. J Bone Joint Surg Am. 2019 May 15;101(10):896-903. doi: 10.2106/JBJS.18.01375. PMID: 31094981.

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