Two years after initial presentation, the patient underwent a physical exam to become an emergency medical technician (EMT). He was able to meet all the physical requirements for his technical college entry, and reported no symptoms. At his last encounter, Mr. B denied any further wrist pain.



5. Discussion


The natural history of AVN in the adult is well established in the literature, both from the standpoint of idiopathic as well as traumatic causes. Unlike the adult form, pediatric AVN is not well represented.


A case presented in 2006 was, at that time, the first documented incidence of osteonecrosis of the capitate in a pediatric patient.1 The case described here shares some minor similarities but demonstrates singular MRI findings. Whereas both pediatric cases went on to full resolution without surgical intervention, this case study clearly represents a transition between the skeletally immature and mature hand.


In the initial case, a gymnast, aged 5 years, presented with a painless loss of motion noted by his instructor.1 He had no other history of pain or trauma. His initial plain films showed changes in the capitate ossification center, predominantly in the proximal portion.1 An MRI taken six weeks after presentation showed diffuse involvement with a predilection for the proximal pole, as would be expected.1

That patient also underwent conservative treatment with splinting, and activity restriction continued until full resolution at his three-year follow-up.1 This appears to be the index case in the published literature.


Adult idiopathic osteonecrosis or AVN of the capitate has been reported a limited number of times in the orthopedic literature and investigated by several authors.2,3 In these cases, it has been thought to share common characteristics with AVN of the scaphoid, with a similar presentation of pain, localized swelling, and decreased range of motion.2

AVN of the capitate has been shown to be unique in its nondominance preference. Anatomically, the capitate is felt to be at risk for AVN in a fashion similar to the scaphoid, as its blood supply enters the proximal portion from a distal pedicle. This has been postulated as the etiology of osteonecrosis in the reported cases.


Most authors agree that osteonecrosis of the capitate is a rare occurrence and, as stated, scarcely reported in the literature. An article published in 1984 demonstrated avascular process of bilateral capitates in an 18-year-old bus driver.3 Unlike his pediatric counterparts, this patient’s symptoms failed to remit, and he went on to surgical replacement at age 25 years.3 The authors were only able to find four published reports on AVN or osteonecrosis of the capitate.


In a more recent article, Botte and colleagues found that osteonecrosis of the capitate was most commonly associated with trauma.2 The researchers indicated that nontraumatic osteonecrosis was comparatively rare and is usually associated with steroid use, gout, or Gaucher disease. They also commented that women appear to be at greater risk for osteonecrosis of the capitate, based on the literature to date. 


Botte’s group further noted that osteonecrosis of the capitate is more common with fractures of the neck that can result in necrosis of the capitate head. These fractures are frequently seen in association with fractures of the scaphoid, as part of a wrist injury referred to as the naviculo-capitate syndrome. The authors suggest that repetitive vibration injury may be a cause of osteonecrosis of the capitate. This may be of interest when examining patients with no trauma who have a history or occupation involving repetitive vibration.2

In the pediatric literature, vascular insufficiency in the proximal pole of the fractured scaphoid leading to necrosis is reported as extremely low in children.4 Many of the cases reported were due to undiagnosed fractures that had not been adequately treated. Treatment with immobilization alone has led to spontaneous revascularization along with healing of the fracture.4

Idiopathic AVN of the lunate (Keinboch disease) or the scaphoid (Preiser disease) has been reported in children, but these are most often linked to other pre-existing conditions. Only one case of Preiser disease requiring surgery has been reported.4, 5

While this case represents only the second report of pediatric idiopathic AVN in published literature, the assumption is that other cases may have existed and gone unreported. With the pain and loss of motion combined with normal plain films, conservative treatment to avoid missing such carpal injuries as a scaphoid fracture may have treated an underlying capitate osteonecrosis.


The complete resolution of symptoms and physical find-ings in these two cases lays the groundwork for a good prognosis in subsequent cases. With this injury as with many other pediatric injuries or insults, patient observation and time seem to bring a satisfactory resolution.


In Mr. B’s case, the age of the patient and the imminence of skeletal maturity are unique and yet offer some framework for treatment guidelines in this age group. Although the patient who presented at age 18 years went on to need surgical intervention, this was not the outcome in a patient just a few months younger chronologically.



6. Summary


As with any patient presenting with findings suspicious for occult fracture, persons with similar symptoms progressing to osteonecrosis must be considered. 


Other than MRI, no diagnostic test is applicable in these cases. This would raise the question as to whether every child presenting with wrist pain and normal plain films needs an MRI. The cost and the logistics of obtaining MRI on every child with wrist pain would be prohibitive. However, the natural history of pediatric idiopathic AVN as presented makes the condition very amenable to conservative management and selective MRI in the judgment of the attending provider.


The case of pediatric idiopathic AVN described here presents a diagnosis that may not have been available previously. The case also offers a satisfactory treatment option and reassurance for the patient’s family. In our very active young patient, a return to full, unrestricted activity and a productive future was not impaired. 

Charles D. Frost, DHSc, MPAS, PA-C, is an Assistant Professor in the physician assistant program at Eastern Virginia Medical School in Norfolk.


References


  1. Humphrey CS, Izadi KD, Esposito PW. Osteonecrosis of the capitate: a pediatric case report. Clin Orthop Relat Res. 2006;447:256-259.

  2. Botte MJ, Pacelli LL, Gelberman RH. Vascularity and osteonecrosis of the wrist. Orthop Clin North Am. 2004;35:405-421, xi.

  3. Bolton-Maggs BG, Helal BH, Revell PA. Bilateral avascular necrosis of the capitate. J Bone Joint Surg Br. 1984;66:557-559. Available at www.bjj.boneandjoint.org.uk/content/66-B/4/557.long.

  4. Gupta A, Kay SPJ, Scheker LR. The Growing Hand: Diagnosis and Management of the Upper Extremity in Children. Elsevier Heath Services; London, United Kingdom: 1999:345-372.

  5. Morrissy RT, Weinstein, SL. Eds. Lovell & Winter’s Pediatric Orthopaedics. 5th ed. Lippincott Williams & Wilkins; Philadelphia: 2001:368-369.


This article originally appeared on Clinical Advisor