A Twenty-Year-Old Man with Right Lower-Extremity Pain

Prior to presentation to the surgical clinic, the symptoms had worsened despite the initial conservative management of physical therapy, NSAIDs, and chiropractic manipulation. For this reason, the patient was offered the option of excision, as a lesion and a mass were shown on preoperative MRI (Figs. 2, 3-A, and 3-B). Given the anterior, posterior, and foraminal extent of the tumor, a staged approach to excise the mass and decompress the nerve root was planned. First, the patient underwent surgical resection of the anterior exostosis lesion via a retroperitoneal approach to the sacrum through a modified Pfannenstiel incision. This portion of the procedure was performed by an orthopaedic oncologist and a general surgeon; it was chosen to be the first procedure primarily because of the availability of the combined surgical team. Exposure of the lesion demonstrated a well-defined osseous mass occluding the right S1 foramen (Fig. 4-A). The S1 nerve root appeared flattened and inflamed, and was overlying the tumor as the nerve exited the foramen. The anterior excision was performed with an osteotome; the base of the osteochondroma was cut, leaving only the intraforaminal and posterior portions of the mass. The second posterior stage of the procedure was performed by the orthopaedic oncologist and the spinal surgeon to remove the remainder of the mass and additionally decompress the S1 nerve root. Through a midline vertical incision and standard posterior sacrum and spinal exposure, the canal was entered and decompressed to the level of the ligamentum flavum with use of a high-speed burr and rongeur. The ligamentum flavum was removed. The nerve roots were retracted, and the posterior portions of the osteochondroma were removed with a rongeur. Cartilage was clearly visible in the canal when it was opened. The neural foramen was then enlarged with Kerrison rongeurs and curets. A Woodson probe was passed through the foramen and confirmed complete decompression of the stenosis caused by the lesion (Fig. 4-B). Histopathology confirmed the diagnosis of benign sacral osteochondroma (Figs. 5-A and 5-B). On postoperative day one following the posterior decompression, the patient reported substantial resolution of the lower-extremity pain on the right side, in particular the stabbing pain extending to the foot. In addition, he demonstrated intact sensation to light touch as well as 5/5 strength in all lower-extremity muscle groups. The postoperative CT showed that the cartilaginous cap had been removed and that there had been enlargement of the S1 neural foramen (Fig. 6). At the one-month follow-up, the patient reported complete resolution of the stabbing pain in the buttocks and the leg pain, with some persistent sensation of “pins and needles” in the foot; on examination, he had normal muscle strength and tone as well as normal sensation. At the two-year follow-up, the patient had no symptoms of leg pain, tingling, or loss of sensation, and he stated that he had been able to resume playing soccer. He did report mild occasional foot tingling, but not severe enough to warrant any medication. Neurologic examination of the bilateral lower extremities showed full strength and intact sensation to light touch in the distribution of the S1 nerve root, including the distribution of the gastrocnemius muscle, the soleus muscle, and the sole of the foot. Radiographs and MRI obtained at that time showed no recurrence of the osteochondroma.

Reference: Maceroli M, Ponnappan R, Shallop B, Vaccaro A, Abraham J. Sacral foraminal osteochondroma causing radiculopathy: a case report. JBJS Case Connector. 2013 Jul 10;3(3):e70.

Primary sacral osteochondroma is a rare diagnosis in spinal surgery. To the best of our knowledge, less than ten cases have been cited in the literature. The authors used a retroperitoneal approach for excision of this lesion. All other reported cases illustrate posterior lesions causing lower back or sciatic nerve pain. In our patient, the lesion traversed the entire neural foramen with a cartilage cap extending from the spinal canal posteriorly through the foramen into the pelvis. On CT and MRI, an osteochondroma will characteristically display continuity with the medullary cavity of native bone, as seen in our patient. On MRI, the cartilaginous cap will demonstrate intermediate-signal intensity on T1-weighted images and high-signal intensity on T2-weighted images. Asymptomatic lesions can be observed. The only treatment option for symptomatic lesions is surgical excision, with the vast majority of patients reporting postoperative satisfaction. Only 1% to 5% of solitary osteochondromas undergo malignant transformation to secondary chondrosarcoma. Local recurrence following complete resection, continued growth despite skeletal maturity, and sudden increases in pain without evidence of neuropathy are concerning for malignant change. Current literature suggests that a cartilaginous cap thickness greater than 2 cm on T2-weighted MRI is worrisome for chondrosarcoma. In the literature, almost all patients with symptomatic sacral osteochondroma underwent tumor resection and dural sac decompression via a posterior approach. In the present case, the lesion’s bulk was anteriorly located on the sacrum, and resection was conducted through a modified Pfannenstiel incision. This allowed maximum exposure of the mass. We were able to remove the bulk of the mass through the anterior excision, but we were unable to sufficiently decompress the foraminal stenosis from the residual mass, necessitating the additional posterior exposure. We performed a posterior decompressive laminectomy and further excision of compressive posterior tumor remnants in the neural foramen to complete the excision. The second stage provided a means of removing the entirety of the remaining mass while protecting local neurovascular structures.

Reference: Maceroli M, Ponnappan R, Shallop B, Vaccaro A, Abraham J. Sacral foraminal osteochondroma causing radiculopathy: a case report. JBJS Case Connector. 2013 Jul 10;3(3):e70.