Case report: pediatric posterior shoulder dislocation

Acute, traumatic posterior dislocations of the shoulder are rare and account for 2% to 5% of all shoulder dislocations in adults.5Hatzis N. Kaar T.K. Wirth M.A. Rockwood Jr., C.A. The often overlooked posterior dislocation of the shoulder.Tex Med. 2001; 97: 62-67PubMed Google Scholar,8Kowalsky M.S. Levine W.N. Traumatic posterior glenohumeral dislocation: classification, pathoanatomy, diagnosis, and treatment.Orthop Clin North Am. 2008; 39 (viii. https://doi.org/10.1016/j.ocl.2008.05.008): 519-533Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar,11McLaughlin H.L. Posterior dislocation of the shoulder.J Bone Joint Surg Am. 1952; 24: 584-590Crossref PubMed Scopus (344) Google Scholar This is in contrast to anterior glenohumeral dislocations, which are more common, occurring 15.5 to 21.7 times more frequently than posterior dislocations.14Robinson C.M. Seah M. Akhtar M.A. The epidemiology, risk of recurrence, and functional outcome after an acute traumatic posterior dislocation of the shoulder.J Bone Joint Surg Am. 2011; 93: 1605-1613https://doi.org/10.2106/JBJS.J.00973Crossref PubMed Scopus (127) Google Scholar In persons younger than 10 years, traumatic shoulder dislocations in general are even more rare and account for less than 2% of all traumatic dislocations.9Li X. Ma R. Nielsen N.M. Gulotta L.V. Dines J.S. Owens B.D. Management of shoulder instability in the skeletally immature patient.J Am Acad Orthop Surg. 2013; 21: 529-537https://doi.org/10.5435/JAAOS-21-09-529Crossref PubMed Scopus (17) Google Scholar Few studies have focused on shoulder dislocation in the very young, skeletally immature patient, as most studies combine them with adolescents or both adult and pediatric patients from a heterogenous population.9Li X. Ma R. Nielsen N.M. Gulotta L.V. Dines J.S. Owens B.D. Management of shoulder instability in the skeletally immature patient.J Am Acad Orthop Surg. 2013; 21: 529-537https://doi.org/10.5435/JAAOS-21-09-529Crossref PubMed Scopus (17) Google Scholar Several different mechanisms have been proposed for posterior shoulder dislocations. High-energy trauma with the shoulder in adduction, flexion, and internal rotation is the most frequent cause of posterior shoulder dislocation.11McLaughlin H.L. Posterior dislocation of the shoulder.J Bone Joint Surg Am. 1952; 24: 584-590Crossref PubMed Scopus (344) Google Scholar,14Robinson C.M. Seah M. Akhtar M.A. The epidemiology, risk of recurrence, and functional outcome after an acute traumatic posterior dislocation of the shoulder.J Bone Joint Surg Am. 2011; 93: 1605-1613https://doi.org/10.2106/JBJS.J.00973Crossref PubMed Scopus (127) Google Scholar Seizures and electrocutions, although rare, have also been associated with posterior shoulder dislocations due to the unbalanced contraction of the shoulder muscles.4Goudie E.B. Murray I.R. Robinson C.M. Instability of the shoulder following seizures.J Bone Joint Surg Br. 2012; 94: 721-728https://doi.org/10.1302/0301-620X.94B6.28259Crossref PubMed Scopus (25) Google Scholar,16Shaw J.L. Bilateral posterior fracture-dislocation of the shoulder and other trauma caused by convulsive seizures.J Bone Joint Surg Am. 1971; 53: 1437-1440Crossref PubMed Scopus (107) Google Scholar It has been reported that diagnosis of posterior shoulder dislocations is often missed or delayed in up to 79% of patients, and so all cases with a potential shoulder dislocation require a high level of suspicion and appropriate imaging.15Rouleau D.M. Hebert-Davis J. Robinson C.M. Acute traumatic posterior shoulder dislocation.J Am Acad Orthop Surg. 2014; 22: 145-152https://doi.org/10.5435/JAAOS-22-03-145Crossref PubMed Scopus (37) Google Scholar Imaging with AP and Velpeau (or axillary, if available) radiographs have been shown to minimize the risk of missing a posterior glenohumeral dislocation.5Hatzis N. Kaar T.K. Wirth M.A. Rockwood Jr., C.A. The often overlooked posterior dislocation of the shoulder.Tex Med. 2001; 97: 62-67PubMed Google Scholar,8Kowalsky M.S. Levine W.N. Traumatic posterior glenohumeral dislocation: classification, pathoanatomy, diagnosis, and treatment.Orthop Clin North Am. 2008; 39 (viii. https://doi.org/10.1016/j.ocl.2008.05.008): 519-533Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar,11McLaughlin H.L. Posterior dislocation of the shoulder.J Bone Joint Surg Am. 1952; 24: 584-590Crossref PubMed Scopus (344) Google Scholar,14Robinson C.M. Seah M. Akhtar M.A. The epidemiology, risk of recurrence, and functional outcome after an acute traumatic posterior dislocation of the shoulder.J Bone Joint Surg Am. 2011; 93: 1605-1613https://doi.org/10.2106/JBJS.J.00973Crossref PubMed Scopus (127) Google Scholar To our knowledge, few reports exist of an acute, traumatic posterior shoulder dislocation in a child, either with2Fannouch G. Khalife Al YI Al Turki A.S. Jawadi A.H. Traumatic pediatric shoulder fracture dislocation treated with closed reduction and intramedullary nailing: A case report.Trauma Case Rep. 2017; 9: 22-27https://doi.org/10.1016/j.tcr.2017.05.003Crossref PubMed Scopus (2) Google Scholar,6Hong S. Nho J.-N. Lee C.-J. Kim J.-B. Kim B. Choi H.-S. Posterior shoulder dislocation with ipsilateral proximal humerus type 2 physeal fracture: case report.J Pediatr Orthop B. 2015; 24: 215-218https://doi.org/10.1097/BPB.0000000000000160Crossref PubMed Scopus (6) Google Scholar or without fracture.1Alogayyel N.S. Aldawodi M.D. Ahmed B. Jawadi A.H. Posterior shoulder dislocation in a 10 year old child: Case report.Ann Med Surg (Lond). 2018; 33: 32-35https://doi.org/10.1016/j.amsu.2018.08.005Crossref PubMed Scopus (0) Google Scholar,3Foster W.S. Ford T.B. Drez Jr., D. Isolated posterior shoulder dislocation in a child. A case report.Am J Sports Med. 1985; 13: 198-200Crossref PubMed Scopus (14) Google Scholar,17Wright J.M. Paletta Jr., G.A. Altchek D.W. Crockett H.C. Sherman M.F. Surgical management of posterior instability in a ten-year-old boy: a case report and literature review.Am J Orthop (Bell Mead NJ). 2000; 29: 633-637PubMed Google Scholar Here we present a case of a young child with a posterior shoulder dislocation and review the relevant literature of this rare entity. A 7-year-old child presented to the emergency department with a high-energy right shoulder injury after landing a jump off his dirt bike. Examination of the shoulder revealed a closed injury with a palpable, posterior prominence of the proximal humerus and periscapular bruising. There was tenderness on palpation of the proximal humeral head and pain with attempted range of motion (ROM). Passive ROM revealed <20 degrees of abduction with inability to externally rotate the shoulder. The patient was distally neurovascularly intact. Radiographs showed a posterior dislocation of the glenohumeral joint (Fig. 1, A-C). There appeared to be a reverse Hill-Sachs lesion in the metaphysis of the humerus toward the anterior aspect involving a portion of the humeral head. Reduction was then obtained with the patient positioned supine and placed under conscious sedation. After gentle in-line traction, pressure was applied to the humeral head in a posterior-to-anterior direction. The shoulder was initially immobilized in a sling with internal rotation; however, postreduction films showed a loss of reduction. The reverse Hill-Sachs lesion may have played a role in the loss of initial reduction. A second reduction was performed with the shoulder then immobilized in an abduction sling and approximately 10-20º of external rotation (ER). Postreduction radiographs, consisting of an AP, lateral, and Velpeau axillary views, confirmed the shoulder was satisfactorily reduced (Fig. 2, A-C). The shoulder was immobilized in the abduction sling for 6 weeks. Repeat X-rays at 1 and 2 weeks after the injury confirmed maintenance of reduction. Physiotherapy was started two weeks after the injury, focusing on pendulum exercises and ROM including ER, forward elevation, and abduction to 90° out of the brace. The patient was advised to avoid internal rotation and adduction beyond neutral. Six weeks after the injury, the patient had near full ROM of his shoulder, lacking slight internal rotation and abduction compared with the uninjured shoulder, and was started on strengthening exercises with no ROM restrictions. Repeat X-rays at 6 weeks after the injury demonstrated concerns for possible avascular necrosis with subtle subchondral sclerosis in the superior aspect of the humeral head (Fig. 3). Serial X-rays were obtained and, at eight months after the injury, there was no evidence of avascular necrosis and minimal contour irregularity (Fig. 4, A-B). A bony exostosis was noted to have developed at the anterior humerus on the axillary view (Fig. 4, C) which was asymptomatic. It was likely related to trauma due to periosteal bone healing near the reverse Hill-Sachs lesion, migrating distally away from the physis with time due to growth. The patient had returned to regular activities, was without pain, and showed excellent rotator cuff strength and shoulder ROM.Figure 4Repeat X-rays obtained eight months after injury with no evidence of AVN. (A) AP, (B) lateral view, and (C) axillary view, which demonstrates a small exostosis on the anterior proximal humerus.View Large Image Figure ViewerDownload (PPT) In children, posterior shoulder dislocations may be due to congenital anomalies of the shoulder girdle, obstetrical paralysis, and voluntary dislocation in those who have general ligamentous laxity.3Foster W.S. Ford T.B. Drez Jr., D. Isolated posterior shoulder dislocation in a child. A case report.Am J Sports Med. 1985; 13: 198-200Crossref PubMed Scopus (14) Google Scholar Traumatic posterior shoulder dislocations are rare and can occur by either direct high energy trauma or by indirect mechanisms causing an imbalance of the shoulder muscles. In this case, the patient sustained his injury from a high-energy traumatic mechanism. A detailed physical examination of the patient is critical for diagnosis of a posterior shoulder dislocation. Pain is reported to be more severe compared with anterior shoulder dislocations.3Foster W.S. Ford T.B. Drez Jr., D. Isolated posterior shoulder dislocation in a child. A case report.Am J Sports Med. 1985; 13: 198-200Crossref PubMed Scopus (14) Google Scholar The patient experiences very limited shoulder abduction, forward elevation, and an inability to externally rotate the shoulder. The humeral head may produce a prominence posteriorly. Appropriate radiographic evaluation is essential to confirm the diagnosis and an axillary view is important to assess for glenohumeral subluxation or dislocation. In this patient, with limited abduction of the shoulder, an axillary view of the shoulder could not be obtained; however, a Velpeau view provided a clear demonstration of the posteriorly dislocated humeral head, also appreciated on the lateral view. The reverse Hill-Sachs lesion noted in this patient is consistent with those seen in the adult population, which are located in the anteromedial aspect of the humeral head.12Moroder P. Tauber M. Scheibel M. Habermeyer P. Imhoff A.B. Liem D. et al.Defect characteristics of reverse Hill-Sachs lesions.Am J Sports Med. 2016; 44: 708-714https://doi.org/10.1177/0363546515621286Crossref PubMed Scopus (17) Google Scholar This lesion may engage on the glenoid in adduction and internal rotation. Treatment for posterior shoulder dislocations involves closed reduction and immobilization. In this case, a successful reduction was achieved after 2 attempts, with reduction maintained using an abduction sling with 10-20º of ER. The new position likely resulted in the reverse Hill-Sachs lesion not engaging with the glenoid. A similar position has been used previously to maintain reduction in an adult patient with bilateral posterior shoulder dislocations associated with reverse Hill-Sachs lesions, using a shoulder spica cast in 20 degrees abduction and 15 degrees of ER for 6 weeks.13Rezazadeh S. Vosoughi A.R. Reduction of bilateral posterior shoulder dislocation with medium impression defect of the humeral head: a case report and review of its treatment.Case Rep Med. 2011; 2011: 124581https://doi.org/10.1155/2011/124581Crossref PubMed Scopus (9) Google Scholar The patient's shoulder was immobilized completely for two weeks, with initiation of ROM with physiotherapy out of the brace at two weeks, although using the immobilizer at all other times until 6 weeks after the injury. While this child was reliable and compliant with treatment, it may be more challenging in younger children or those less compliant. More rigid immobilization, such as a shoulder spica cast7Jin S. Cai H. Xu Y. Shoulder dislocation combined with proximal humerus fracture in children: a case report and literature review.Medicine (Baltimore). 2017; 96: e8977https://doi.org/10.1097/MD.0000000000008977Crossref PubMed Scopus (4) Google Scholar may need to be considered if ongoing instability is demonstrated in the setting of poor compliance. The shoulder in this case remained stable and there was no need to proceed to operative stabilization; however, ongoing or recurrent instability may require surgical intervention. Wright et al describe a case of a 10-year-old with recurrent instability treated surgically with a glenoid-based posterior capsular shift.17Wright J.M. Paletta Jr., G.A. Altchek D.W. Crockett H.C. Sherman M.F. Surgical management of posterior instability in a ten-year-old boy: a case report and literature review.Am J Orthop (Bell Mead NJ). 2000; 29: 633-637PubMed Google Scholar A recent systematic review investigated traumatic shoulder instability in children younger than 18 years and suggested that those having surgical stabilization had lower rates of recurrent instability; however, the age range was broad, only 2 of 705 shoulders sustained a posterior dislocation, and they found that further studies are required to clarify several points regarding treatment.10Longo U.G. van der Linde J.A. Loppini M. Coco V. Poolman R.W. Denaro V. Surgical versus nonoperative treatment in patients up to 18 years old with traumatic shoulder instability: a systematic review and quantitative synthesis of the literature.Arthroscopy. 2016; 32: 944-952https://doi.org/10.1016/j.arthro.2015.10.020Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar A modified McLaughlin procedure could be considered in the setting of persistent instability in an adolescent patient; however, it could be problematic in a younger patient. Owing to the proximity to the physis, this would risk injury to growth, resulting in limb shortening or angular deformity. To our knowledge, there is no reported literature on a McLaughlin procedure used in the pediatric population. However, with the growth and remodeling potential observed in pediatric patients with periosteal bone healing, this defect is likely to improve over time. Posterior shoulder dislocations are rare, and even more rare in the pediatric population. These injuries can be missed and thus a good history, physical examination, and appropriate imaging are essential to reach the correct diagnosis. Limited ROM due to pain on presentation can make it difficult to obtain a standard axillary view so a Velpeau view is useful in the acute setting. Positioning the shoulder in abduction and ER helps to maintain the reduction. Serial radiographs may be of benefit to monitor for sequelae.

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