HETEROTOPIC OSSIFICATION IN THE MIDLINE INCISION FOLLOWING ABDOMINAL TRAUMA SURGERY IN POLYTRAUMA PATIENT Seung Je Go, Young Hoon Sul, Jin Bong Ye, Jin Young Lee, JinSukLee, Soo Young Yoon, Hong Rye Kim, Jung Hee Choi
Seung Je Go, Young Hoon Sul, Jin Bong Ye, Jin Young Lee, JinSukLee, Soo Young Yoon, Hong Rye Kim, Jung Hee Choi
Chungbuk National University Hospital,
Cheongju, Korea
Heterotopic ossification (HO) refers to a bone formation in all types of soft tissues outside the skeletal system. It is first described by Riedel in 1883, but given the probability that HO is extremely rarely reported, the incidence is unclear. The etiology of pathology is not consensual, and the formation of HO is still considered an extremely rare complication. Various treatments have been attempted, but none of these has yet been clearly established. Here we present a patient with HO that was surgically resected five months after abdominal surgery for polytrauma including traumatic hemoperitoneum due to multiple jejunal perforations, and then discuss the current understandings of the etiology and treatment options of HO with related literature reviews.
CASE
A 60-year-old man was admitted with complaints of progressive epigastric discomfort and more aggravated postprandial fullness disturbing his posture for the past 5 months. He had received three laparotomies. The first surgery was a damage control laparotomy, which was done by a long midline abdominal incision for traumatic hemoperitoneum and jejunal perforations due to traffic accident five month ago.
On physical examination, a hard mass was palpable in the abdominal incision site extending from the subxiphoid region to the upper umbilical region. Except for the palpable hard mass, no additional abnormal findings were observed. A computed tomography (CT) scan of the abdomen revealed a vertically oriented, bifurcated, and linear calcified lesion with the same density as other bony structures in previous abdominal incision site (fig.1). At operation, the calcified lesion in the abdominal incision site was found in the preperitoneal space (fig.2), a total excision was done without severe adhesion around tissue. The size of the excised specimen was10 x 3.5 x 0.8 cm, and the histopathology revealed mature bone trabeculae (fig. 3). The symptom was completely resolved after the operation, and he was discharged without any complications.
Figure 1
Computed Tomography (CT) scan. The coronal view (A) and the sagittal view (B) of CT scans show calcified tissue (white arrows) in the midlineincision site
Figure 2
Operative field. Surgical excision of HO was done
Figure 3
Histopathology of the excised specimen: A – gross picture (size 10 x 3.5 x 0.8 cm); B – histologic section: mature bone tissue (100 x HE)
DISCUSSION
HO is defined as the metaplastic phenomenon where mature, lamellar bone components are formed in soft tissue such as skin, scars, subcutaneous fat, and muscle along with mesenteric tissues[1]. HO is a common finding after orthopedic surgery and is seen in 2to 7% of patients who underwent hip surgery including hip joint capsule[2,3]. Although it is known to be a common complication after orthopedic surgery, it is recognized as a very rare phenomenon after abdominal surgery. A recent study reported that HO was observed in about 25% of 152 patients who underwent abdominal incision[4].Unfortunately, definite data of the symptoms associated with HO in patients who underwent abdominal incision has not yet been established. Perhaps this limitation is due the small number of patients. It is certainly that HO is male predominant, with male to female ratio about 10:1, age distribution ranging from 18 to 91 years, mostly middle-aged individuals [5,6]. Most ectopic bones appear to form within one year after surgery, are self-limited and even regressive [4].In our case, five months had elapsed since the first laparotomy in a middle-aged male.
The pathogenesis of HO has not been clearly established, although it may be due to osteoblastic metaplasia of multipotential mesenchymal cells as a response to severe inflammatory stimuli from trauma, or may be caused by traumatic or surgical implantation of periosteum into the soft tissues [1]. This process has been referred to as an osteogenic induction, where the mesenchymal cell, which normally does not participate in bone formation, gains the property of forming bones [7]. In our case, HO probably occurred due to repetitive surgical injuries, with maintained inflammatory stimulus resulting in bone formation
In previously reported cases of HO associated with abdominal surgery or trauma, most of the symptomatic patients complained of pain, swelling, and uncomfortable movements, which also caused disability in their daily activities. In our case, the patient presented progressive epigastric discomfort and postprandial fullness disturbing his posture.
On physical exam, a hard mass was palpable at the afflicted area [8]. If HO is suspected, radiologic imaging test is required. A plain X-ray, ultrasonography, CT scan, or magnetic resonance imaging can be useful for accurate diagnosis. When radiologic imaging test is used for diagnosis, care should be taken to distinguish HO from other mostly benign entity lesions and other postoperative complications such as surgical site infection and retained foreign body[4].In Our case, a hard mass extending from the subxiphoid region to the upper umbilical region was noted on clinical exam, and then plain X-ray and CT scan were performed.
The prognosis of HO is generally good, rarely causing complications. Several case reports showed that the bone marrow of HO can play an independent role in hematopoiesis, with histological evidence of normal trilineage hematopoiesis [9].Cases of osteochondroma of the xyphoid appendix into the abdominal wall scar have also been reported [10].Although HO is mostly benign, it is rarely reported as a malignant lesion such as osteosarcoma [11].
Although there is no definitive guideline of the treatment methods applicable to the scarring of the abdominal wall, several treatment methods can be applied. Conservative treatment can be possible, avoiding surgery to prevent further ossification. However, surgical excision with primary closure can be the treatment of choice for symptomatic HO [8]. Recurrence is very rare, and it is known that immature bone tissue is depleted after excision and sufficient treatment effect can be obtained by removing only mature ossifications [12].Treatment methods known to be effective in preventing recurrence of HO include radiation therapy(RT), and NSAIDs. Although RT has been widely used as a preventive and treatment method for HO after orthopedic surgery, the advantages of application of RT in abdominal surgery are still lacking and controversial [7]. NSAIDs, such as indomethacin, diphosphates, and especially etidronate disdium, are widely used in HO[13]. Animal studies in which demineralized bone matrix was inserted in the abdominal muscle to induce HO, have shown that these pharmaceutical agents may delay, and partially prevent postoperative recurrence of HO [14]. In our case, the symptomatic HO was surgically excised, and then postoperative prophylactic radiation therapies were performed for 5 days with low dose radiation(700 cGy). No pharmaceutical agent was prescribed for prevention.
CONCLUSION
HO is a rare pathology, with many unknown aspects. We recommend the surgical resection as a selective therapy until a verified study of HO treatment is published.