Heterotopic Ossification During a Ventral Hernia Repair

Abstract and Introduction

Abstract

Introduction: Heterotopic ossification involves the formation of trabecular bone outside of its usual anatomic location. While it is a well-known entity in orthopedic and spinal injury literature, it has also been observed after midline laparotomy and severe burns.

Methods/Case Report: We present a case of a 69-year-old man who presented for ventral hernia repair after a prolonged postoperative course following colectomy involving an open abdomen with eventual closure with skin grafting.

Results: Two large calcified objects were encountered during the excision of the skin graft from the small intestine and during the component separation. They had grown into the anterior fascia and rectus muscle and interdigitated between loops of the small bowel. After careful resection of the 2 calcified objects, a ventral hernia repair with a component separation was successfully performed. Pathology was consistent with heterotopic ossification. After 18 months, there was no clinical evidence of recurrence.

Discussion: Heterotopic ossification is not frequently encountered during ventral hernia repairs, but its presence can complicate repair. Resection is the only option in the context of hernia repair. If recognized preoperatively, waiting up to a year for the bone to mature before excision has been suggested, but there is minimal data to support this. Consultation with a general surgeon is also advised in case the calcified tissue involves the underlying viscera.

Introduction

Heterotopic ossification (HO) involves the formation of trabecular bone outside of its usual anatomic location and has been described in various forms and under various names since the 18th century.^[1,2] It is distinct from pathologies such as calcinosis and ectopic calcification because pathologically it comprises structural components similar to bone as opposed to the deposition of calcium in tissue.^[3,4] Although multiple subtypes have been described, the most relevant to ventral hernia repair is myositis ossificans traumatica.^[5] This condition results in the development of ossified tissue in muscles, tendons, and ligaments^[6] and is frequently observed in the spinal injury and orthopedics literature. Heterotopic ossification of varying degrees of severity and clinical significance has been documented in 5% to 90% of patients following total hip arthroplasty,^[6,7] in 11% of patients following traumatic brain injury, and in 20% of patients following spinal cord injuries.^[8]

While HO is a known sequela of severe neurological injury and arthroplasty, it has also been documented in patients following trauma or severe burns, as well as after laparotomy for abdominal surgery.^[4,5,9–15] It is estimated that up to 25% of midline wounds develop some amount of HO.^[11] Heterotopic ossification has been observed in all age groups including young children.^[16] The true incidence of HO is unknown but is likely higher due to underreporting. To our knowledge, we present the first case of HO of the ventral abdominal wall and peritoneal cavity that invaded in an almost malignant fashion.