Fractured osteochondroma presenting with popliteal pseudoaneurysm: Case report and review of literature.

Osteochondroma, the most common tumor of bone, is usually asymptomatic. Vascular complications are an atypical presentation and include true or false aneurysm formation, deep venous thrombosis, and arterial insufficiency. A review of the English literature identified 130 cases of osteochondroma-related vascular complications. We describe the case of a 38-year-old man presenting with left calf pain and swelling who was diagnosed with the rare constellation of a popliteal pseudoaneurysm and incidental peroneal vein thrombosis secondary to a fractured femoral sessile osteochondroma. This was treated with resection of the osteochondroma, excision of the aneurysm, and primary end-to-end anastomosis of the artery.

Osteochondromas are the most common bone tumors, representing 10% to 15% with an incidence of 3% in the population., Most are asymptomatic and discovered incidentally. Rarely, they are manifested with fracture or complications related to compression into adjacent soft tissue., Vascular complications are an atypical presentation of osteochondromas and include true or false aneurysms, vascular compression, arterial ischemia, and venous thrombosis. We reviewed the English literature and describe a case of a fractured sessile osteochondroma presenting with a popliteal pseudoaneurysm and incidental peroneal deep venous thrombosis.

Case report

A 38-year-old man presented to his local physician with 1 week of pain and swelling of the left thigh and calf. Clinical examination demonstrated a pulsatile expansile mass on the distal medial thigh with intact pedal pulses. The patient had no significant past medical history other than smoking electronic cigarettes and worked as an electrician. An arterial and venous Doppler ultrasound examination demonstrated a large popliteal pseudoaneurysm. Incidentally, a peroneal deep venous thrombus was observed, probably due to local compression and mass effect from the adjacent pseudoaneurysm. The patient was prescribed rivaroxaban for deep venous thrombosis and underwent further investigation with computed tomography angiography (Fig 1). This demonstrated an osseous lesion projecting posteromedially in continuity with the distal femoral shaft, suggestive of an osteochondroma. Irregular bone cortices with sharp spicules were indicative of fracture. The popliteal artery pseudoaneurysm measured 33 × 33 × 36 mm, with a 4-mm neck that abutted the bone projection. There was normal inflow and outflow with three-vessel runoff to the ankles.

Fig 1

On computed tomography angiography axial (A) and sagittal (B) slices, sessile osteochondroma with bone cortical breach representing fracture (red arrow) and sharp bone spicule (blue arrow). On sagittal (C) and coronal (D) slices, considerable thrombus fills the pseudoaneurysm sac; however, opacification is seen proximally and distally. A bone spicule (arrow) can be seen penetrating the pseudoaneurysm in (C).

The patient was transferred to a tertiary hospital with both a vascular surgery service and an orthopedics sarcoma service for further management. The bone lesion was considered a benign osteochondroma without malignant features. Nevertheless, given that vascular complications had occurred, resection of the bone lesion with concurrent pseudoaneurysm repair was planned.

A medial supragenicular exposure was performed. Proximal control was obtained at the superficial femoral artery in Hunter canal, and distal control was obtained at the above-knee popliteal artery (Fig 2). After systemic heparinization, the pseudoaneurysm was incised, a moderate amount of thrombus removed, and the redundant vessel wall excised. Given the laxity of the popliteal artery, the artery was repaired by direct end-to-end anastomosis of healthy normal artery (Fig 3). The osteochondroma was noted to be fractured, with a resultant sharp protuberant surface that had punctured the popliteal artery on its anterior surface. It was removed with an osteotome, and the edges were smoothed with a rasp (Fig 4). Postoperative histologic evaluation confirmed the diagnosis of a benign osteochondroma. The patient had an unremarkable recovery and was discharged on postoperative day 7.

Fig 2

Large popliteal pseudoaneurysm (arrow). Medial supragenicular exposure.

Fig 3

After pseudoaneurysm excision with end-to-end anastomosis (arrow).

Fig 4

Resected osteochondroma specimen.

The patient consented to the use of medical history and images for educational purposes.

Discussion

Osteochondromas are common benign bone tumors that tend to be asymptomatic and diagnosed incidentally. Many remain undiagnosed, and reported frequencies are likely to underestimate their true prevalence. Osteochondromas have a soft, pliable cartilage cap that later ossifies. They are usually smooth and rarely cause arterial injury; however, chronic arterial pulsation against the bone prominence may cause vessel wall injury. Rarely, osteochondromas may be complicated by fracture secondary to strenuous physical exercise or trauma, resulting in sharp bone spicules that pierce the artery, causing pseudoaneurysm formation.,5, 6, 7

Our review of the English literature identified 130 vascular complications from osteochondroma (Table). Vascular complications were most commonly due to femoral osteochondromas (66.2%); however, other sites included the tibia (15.4%), fibula (7.7%), humerus (5.4%), clavicle (1.5%), ribs (1.5%), pubic ramus (0.8%), scapula (0.8%), and cervical vertebra (0.8%). The popliteal artery was involved in 66% of cases, and popliteal pseudoaneurysms were the most prevalent vascular complication (49%). Nonetheless, pseudoaneurysms of the subclavian, brachial, superficial femoral, medial femoral circumflex, and posterior tibial arteries have also been described.8, 9, 10, 11, 12 The popliteal artery is often injured because of the increased frequency of osteochondromas in the distal femur. Furthermore, the limited mobility of the artery at the proximal adductor canal may facilitate tethering to the osteochondroma., In our case, the pseudoaneurysm manifested as a painful, pulsatile mass; however, pseudoaneurysms may also be manifested with claudication, acute limb ischemia, and rupture.,,

Table

Vascular complications reported in English literature and their treatment

Vascular lesion	Vessel	Procedure
Pseudoaneurysm, 73 (56.2%)	Popliteal artery, 55Superficial femoral artery, 8Brachial artery, 6Subclavian artery, 1Collateral of popliteal artery, 1Posterior tibial artery, 1Medial femoral circumflex artery, 1	Angiography + thrombectomy + vein patch, 1Embolization coiling + direct repair, 1Coil embolization, 1Bypass (vein), 13Bypass (prosthetic), 2Direct repair, 23Aneurysm resection, end-to-end anastomosis, 11Interposition graft, 5Ligation, 2Vein patch, 11PTFE patch, 1Cilostazol and walking program, 1No management, 1
Pseudoaneurysm and deep venous thrombosis, 7 (5.4%)	Popliteal artery, popliteal vein, 7	Aneurysm resection, end-to-end anastomosis, 3Bypass (vein), 1Direct repair, 1Interposition graft, 1Ligation, 1
Vascular compression, 14 (10.8%)	Popliteal artery, 9Superficial femoral artery, 2Common femoral artery, 1Profunda femoral artery, 1Brachial artery, 1	Bypass (vein), 9Osteochondroma resection, 4End-to-end anastomosis, 1
Arterial thrombosis, 14 (10.8%)	Popliteal artery, 8Superficial femoral artery, 2Tibioperoneal trunk, 1Vertebral artery, 1Common carotid artery, 1Anterior tibial artery, 1	Vein patch, 4Osteochondroma resection, 4Bypass (vein), 3Bypass (prosthetic), 1End-to-end anastomosis, 1Anticoagulation, 1
Arterial thrombosis + deep venous thrombosis, 1 (0.8%)	Superficial femoral artery, popliteal vein, 1	Bypass (vein), 1
Entrapment, 5 (3.8%)	Popliteal artery, 4Tibioperoneal trunk, 1	Osteochondroma resection, 5
Entrapment + deep venous thrombosis, 1 (0.8%)	Popliteal artery, popliteal vein, 1	Osteochondroma resection, 1
Deep venous thrombosis, 11 (8.5%)	Popliteal vein, 7Femoral vein, 3Subclavian vein, 1	Osteochondroma resection, 8Interposition graft, 1Anticoagulation, 2
Thoracic outlet syndrome, 2 (1.5%)	Subclavian artery, 2	Osteochondroma resection, 2
Arteriovenous fistula and aneurysm, 1 (0.8%)	Superficial femoral artery and femoral vein, 1	Aneurysm resection with end-to-end anastomosis and direct repair to vein, 1
Vein aneurysm, 1 (0.8%)	Popliteal vein, 1	Anticoagulation, 1

PTFE, Polytetrafluoroethylene.

Deep venous thrombosis in association with osteochondroma is infrequent. The osteochondroma exerts mass effect on the vein and induces thrombosis. However, in cases of sessile osteochondroma, it has been observed that deep venous thrombosis formation requires additional vascular compression from a concurrent pseudoaneurysm, as occurred in our case.

Various other vascular lesions are described. Lucarelli and Subram reported a case of type IV popliteal entrapment treated with tibial osteochondroma resection and release of popliteus muscle fibrous bands. O'Brien et al reported venous thoracic outlet syndrome with subclavian vein thrombosis from a clavicular osteochondroma. Stroke secondary to osteochondroma has also been described. Gouicem et al described a common carotid artery occlusion from a clavicle osteochondroma that was resected, and Altaf et al described vertebral artery occlusion from a first cervical vertebra osteochondroma managed with anticoagulation. Sethi et al described a popliteal vein aneurysm managed conservatively. One case of arteriovenous fistula in which a popliteal pseudoaneurysm eroded into the accompanying vein has been reported. Aneurysm resection with end-to-end anastomosis and repair of the vein defect was done. Notably, the causative osteochondroma was diagnosed 6 years earlier, which may support prophylactic osteochondroma resection when adjacent vascular structures are present.

Most cases were managed by osteochondroma resection with or without open vascular reconstruction. Open surgical options include bypass and interposition grafting, direct repair, patch angioplasty, and aneurysm resection with direct end-to-end anastomosis. Endovascular management is infrequently described. In two hybrid procedures, one patient underwent thrombectomy for embolus in the tibioperoneal trunk with subsequent vein patching of the popliteal pseudoaneurysm, and another had coil embolization of the pseudoaneurysm followed by direct repair of the artery 1 week later., Only one patient had isolated endovascular treatment, undergoing coil embolization of a medial femoral circumflex pseudoaneurysm. One patient with intermittent claudication was managed conservatively with cilostazol and a walking program in anticipation of future collateral formation. The paucity of endovascular use reflects the necessity of resecting the causative osteochondroma, which lends itself to concomitant open vascular repair. Patients presenting with symptoms of vascular compression, such as thoracic outlet syndrome, without significant arterial injury can be satisfactorily treated with osteochondroma resection alone without specific vascular reconstruction.

Local recurrence of osteochondroma after resection is low at 1.8% but may be higher in skeletally immature patients. Delayed resection should be considered until complete skeletal development in select cases. To avoid recurrence, all remnants of tumor cartilage, bone, and perichondrium must be removed. Two cases are reported of delayed pseudoaneurysm formation after incomplete osteochondroma resection. Otsuka et al reported a partially resected osteochondroma that resulted in pseudoaneurysm formation 5 years later because of ongoing arterial trauma from the residual tumor's irregular edges. Similarly, Scotti et al reported brachial pseudoaneurysm presenting with rupture secondary to a partially resected osteochondroma 3 years earlier.

Conclusions

The constellation of osteochondroma fracture with arterial pseudoaneurysm and deep venous thrombosis is uncommon. Although it is benign, serious vascular complications can occur because of the relationship with adjacent structures. Osteochondroma resection must be complete to prevent residual tumor, which can lead to recurrence or ongoing vascular injury. This case underscores the arterial and venous complications of osteochondroma and the association between pseudoaneurysm and deep venous thrombosis.