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Long-term fate of the vascularized iliac crest bone graft for mandibular reconstruction
Long-Term Fate of the Vascularized Iliac Urest Bone Graft for Mandibular Reconstruction Frederick N. Lukash, MD, Noel S. Tenenbaum, MD, Gerard Moskowitz, MD, NewHydePark, New York
Vascularized bone grafts, such as the iliac crest, have become a major tool for mandibular reconstruction. Due to the growing trend toward immediate bone replacement followed by implant osseointegration and dental rehabilitation, further understanding o f the long-term characteristics of these grafts is essential. Early postoperative bone scans demonstrate increased activity within the vascularized graft relative to surrounding bone. This study addressed the use of bone SPECT (single photon emission computed tomography) scintigraphy as a long-term method of evaluating the integrity of vascularized bone grafts.
ver the past decade, vascularized iliac crest bone grafts have been used with increasing frequency for O purposes of mandibular reconstruction. Originally described by Taylor [1], this free osteocutaneous flap based on the deep circumflex iliac artery offers the reconstructive surgeon the capability of utilizing a large quantity of cortico-cancellous bone with a contour similar to that of the mandible. With the successful application of this technique, many surgeons have expanded the goals of mandibular reconstruction to include that of functional mandibular reconstruction, featuring a fixed osteo-dental prosthesis [2,3]. Despite the aforementioned advances, much remains unknown regarding the long-term fate of the vascularized iliac crest graft or the appropriate means of monitoring such grafts. Bone graft biopsy has been shown to adequately assess graft viability [4]; however, this technique is invasive and may damage the vascularized graft. Although bone scans have been demonstrated to accurately assess anastomotic patency perioperatively [5,6], traditional two-dimensional scans lacked the necessary sensitivity to assess such grafts on a long-term basis due to the inability to distinguish graft activity from overlying structures. This technical flaw has been resolved with the From the Division of Plastic Surgery, Department of Surgery (FNL, NST), and the Division of Nuclear Medicine, Department of Radiology (GM), Long Island Jewish Medical Center, New Hyde Park, New York. Requests for reprints should be addressed to Frederick N. Lukash, MD, 1129 Northern Boulevard, Manhasset, New York 11030. Presented at the 36th Annual Meeting of the Society of Head and Neck Surgeons, Washington, DC, May 19-22, 1990.
advent of bone SPECT (single photon emission computed tomography) scintigraphy, which accurately quantitates graft activity on a three-dimensional basis [7,8]. Due to the expanding role of vascularized iliac crest grafts for immediate and secondary mandibular reconstruction, the long-term fate and means of evaluating these grafts are critical, particularly if such grafts are to undergo further manipulation and implant osseointegration. It was the goal of this study to evaluate the longterm fate of the vascularized iliac crest composite graft utilizing bone SPECT scans and correlate these findings with bone graft biopsy and clinical evaluation. PATIENTS AND METHODS In this series, nine patients underwent vascularized iliac crest bone grafts for mandibular reconstruction. Patients ranged in age from 17 to 67 years. Squamous cell carcinoma was the most frequent admitting diagnosis and was present in 78% of patients. One patient was treated for osteogenic sarcoma of the mandible, and the other patient had a post-traumatic mandibular defect, Overall, seven patients underwent secondary mandibular reconstruction utilizing a vascularized iliac crest graft, while two patients had immediate reconstruction using the aforementioned graft followed by postoperative radiotherapy (Table I). Each patient was evaluated at 48 hours postoperatively using bone SPECT scintigraphy. SPECT scans were repeated 1 year postoperatively and included static as well as dynamic phases. All scans were performed using 20 mCi of the radiopharmaceutical technetium-99m methylene diphosphonate. At 3 hours after injection, scinti-images were obtained using a Siemens dual-headed ROTA camera at 6-degree increments until the mandible had been evaluated for a total of 360 degrees [9]. These images were stored in 64 • 64 pixel frames on a Siemens computer system (VAX 11/750). Scan results were correlated with bone graft biopsy performed at the time of plate fixator removal, as well as physical examination. RESULTS Patients studied within this series could be categorized into three groups. Group 1 featured three patients who underwent mandibular reconstruction into a nonirradiated recipient bed. Group 2 consisted of four patients who underwent preoperative radiotherapy to the recipient mandibular bed prior to secondary mandibular reconstruction. Finally, both patients in Group 3 underwent immediate mandibular reconstruction followed by radiotherapy to the recipient bed as well as to the vascularized iliac crest graft (Table I). At 48 hours postoperatively, eight of nine SPECT scans were noted to have enhanced activity within the
THE AMERICAN JOURNAL OF SURGERY
VOLUME 160 OCTOBER 1990
399
LUKASH ET AL
TABLE I
Vascularized lilac Crest Bone Grafts for Mandibular Reconstruction in Nine Patients
Group 1
Diagnosis SCC SCC Blast injury
2
SCC Osteogenic sarcoma SCC SCC
3
SCC SCC
Extirpative Procedure
Mandibular Reconstruction
Preoperative Radiotherapy*
SPECT Scan 48 hrs
Postoperative Radiotherapy
SPECT Scan 1 yr
Hemimandibulectorny Segmental mandibulectomy Angle-to-angle defect Angle-to-angle mandibulectomy Hemimandibulectomy
Secondary Secondary
---
+ -I-
---
+ Jr
Normal Normal
Yes Yes
Secondary
--
Jr
--
+
Normal
Yes
Secondary
Jr
-I-
--
+
Normal
Yes
Secondary
Jr
Jr
--
Jr
Normal
Yes
Hemimandibulectomy Segmental mandibulectomy Angle-to-angle mandibulectomy Arch mar~ibulectomy
Secondary Secondary
-IJr
-I--
---
Jr Jr/--
Normal Accelular
No No
immediate
--
+
Jr
+
Normal
No
Immediate
--
+
Jr
--
Acellular
No
Bone Biopsy
Osseointegration
* Plus signs indicate "hot" scans; minus signs indicate "cold" scans. SCC = squamous cell carcinoma.
Figure 1. SPECT scan at 4 8 hours reveals enhanced vascularized graft activity.
vascularized graft relative to the surrounding calvarium, suggesting anastomotic patency. One "cold" scan, suggestive of early graft occlusion, was observed 48 hours postoperatively. Seven of the original "hot" scans continued to exhibit elevated mean activity ratios (MAR) at 1 year after reconstruction. The cold SPECT scan observed at 1 year postoperatively occurred in a patient who had undergone immediate reconstruction followed by radiotherapy. These findings are consistent with obliterative endarteritis secondary to radiotherapy and were confirmed by bone graft biopsy, which revealed sclerotic bone. Clinical evaluation revealed a fibrous union of this patient's mandibular graft. 400
THE AMERICAN JOURNAL OF SURGERY
Figure 2. SPECT scan at I year postoperatively reveals enhancement of vascularized graft despite post-reconstructive radiotherap y (6,000 rad).
Perhaps most important were the SPECT scan findings observed in a patient who also had undergone immediate mandibular reconstruction. This patient was noted to have a high degree of activity (MAR) on the SPECT scan at 1 year postoperatively, despite having undergone radiotherapy to the recipient bed and vascularized graft (Figures 1 and 2). The viability of this metabolically active, albeit irradiated, graft was confirmed by bone
VOLUME 160
OCTOBER 1990
VASCULARIZED BONE GRAFT FOR MANDIBULAR RECONSTRUCTION
graft biopsy. To date, this patient remains edentulous because of fear of osteoradionecrosis. Thus far, five patients have successfully undergone implant osseointegration, and now maintain a fixed osteo-dental prosthesis. COMMENTS Since its description by Taylor [1], the vascularized iliac crest composite graft has become a mainstay of mandibular reconstruction. As experience with this technique has accumulated, the creation of a fixed osteodental prosthesis through the utilization of implant osseointegration techniques has become possible [2,3]. Despite these advances, however, little information exists regarding the long-term characteristics of the vascularized iliac crest graft. This study demonstrates the successful application of bone S P E C T scintigraphy for purposes of noninvasively evaluating the long-term viability of vascularized iliac crest grafts used for mandibular reconstruction. Furthermore, it appears that such grafts maintain an enhanced level of metabolic activity on a long-term basis, making this graft suitable for implant osseointegration and functional mandibular reconstruction utilizing a fixed osteodental unit. Such findings were observed in those patients who featured a "hostile" environment secondary to preoperative radiotherapy to the recipient mandibular bed, in addition to those patients who were never treated with radiotherapy. Finally, bone SPECT scintigraphy may be useful in identifying select patients who have not experienced the
deleterious effects of radiotherapy to the vascularized bone graft. Such patients may ultimately prove to be suitable candidates for the mandibular graft stresses associated with a fixed osteo-dental prosthesis and thereby benefit from a truly functional masticatory process.
REFERENCES 1. Taylor GI. Reconstruction of the mandible with free composite iliac bone grafts. Ann Plast Surg 1982; 9: 361-76. 2. Lukash FN, Sachs SA. Functional mandibular reconstruction: prevention of the oral invalid. Plast Reconstr Surg 1989; 84: 22733. 3. Lukash RN, Sachs SA, Fischman B, Attie JN. Osseointegrated denture in a vascularized bone transfer: functional jaw reconstruction. Ann Plast Surg 1987; 19: 538-44. 4. Arata MA, Wood MB, Cooney WP IlL Revascularizedsegmental diaphysealbone transfers in the canine: an analysisof viability. J Reconstr Microsurg 1984; 1: 11-9. 5. Bos KE. Bone scintigraphy of experimental composite bone grafts revascularizedby microvascularanastomoses.Plast Reconstr Surg 1979; 64: 353-60. 6. Berggren A, Weiland A J, Ostrup LT. Bone scintigraphy in evaluating the viability of composite bone grafts revascularized by microvascular anastomoses, conventional autogenous bone grafts, and free non-revascularized periosteal grafts. J Bone Joint Surg 1982; 64: 799-809. 7. Yaremchuk M J, May JW. Correspondence. J Bone Joint Surg 1983; 65: 279-80. 8. Myers M J, Fazio F. The case for emission computed tomography with a rotating gamma camera. Appl Radiol 1981; 10:127-34. 9. MoskowitzGW, Lukash FN. Evaluation of bone graft viability. Semin Nucl Med 1988; 18: 246-54.
THE AMERICAN JOURNAL OFSURGERY
VOLUME 160 OCTOBER 1990 401
Vascularized bone grafts, such as the iliac crest, have become a major tool for mandibular reconstruction. Due to the growing trend toward immediate bone replacement followed by implant osseointegration and dental rehabilitation, further understanding o f the long-term characteristics of these grafts is essential. Early postoperative bone scans demonstrate increased activity within the vascularized graft relative to surrounding bone. This study addressed the use of bone SPECT (single photon emission computed tomography) scintigraphy as a long-term method of evaluating the integrity of vascularized bone grafts.
ver the past decade, vascularized iliac crest bone grafts have been used with increasing frequency for O purposes of mandibular reconstruction. Originally described by Taylor [1], this free osteocutaneous flap based on the deep circumflex iliac artery offers the reconstructive surgeon the capability of utilizing a large quantity of cortico-cancellous bone with a contour similar to that of the mandible. With the successful application of this technique, many surgeons have expanded the goals of mandibular reconstruction to include that of functional mandibular reconstruction, featuring a fixed osteo-dental prosthesis [2,3]. Despite the aforementioned advances, much remains unknown regarding the long-term fate of the vascularized iliac crest graft or the appropriate means of monitoring such grafts. Bone graft biopsy has been shown to adequately assess graft viability [4]; however, this technique is invasive and may damage the vascularized graft. Although bone scans have been demonstrated to accurately assess anastomotic patency perioperatively [5,6], traditional two-dimensional scans lacked the necessary sensitivity to assess such grafts on a long-term basis due to the inability to distinguish graft activity from overlying structures. This technical flaw has been resolved with the From the Division of Plastic Surgery, Department of Surgery (FNL, NST), and the Division of Nuclear Medicine, Department of Radiology (GM), Long Island Jewish Medical Center, New Hyde Park, New York. Requests for reprints should be addressed to Frederick N. Lukash, MD, 1129 Northern Boulevard, Manhasset, New York 11030. Presented at the 36th Annual Meeting of the Society of Head and Neck Surgeons, Washington, DC, May 19-22, 1990.
advent of bone SPECT (single photon emission computed tomography) scintigraphy, which accurately quantitates graft activity on a three-dimensional basis [7,8]. Due to the expanding role of vascularized iliac crest grafts for immediate and secondary mandibular reconstruction, the long-term fate and means of evaluating these grafts are critical, particularly if such grafts are to undergo further manipulation and implant osseointegration. It was the goal of this study to evaluate the longterm fate of the vascularized iliac crest composite graft utilizing bone SPECT scans and correlate these findings with bone graft biopsy and clinical evaluation. PATIENTS AND METHODS In this series, nine patients underwent vascularized iliac crest bone grafts for mandibular reconstruction. Patients ranged in age from 17 to 67 years. Squamous cell carcinoma was the most frequent admitting diagnosis and was present in 78% of patients. One patient was treated for osteogenic sarcoma of the mandible, and the other patient had a post-traumatic mandibular defect, Overall, seven patients underwent secondary mandibular reconstruction utilizing a vascularized iliac crest graft, while two patients had immediate reconstruction using the aforementioned graft followed by postoperative radiotherapy (Table I). Each patient was evaluated at 48 hours postoperatively using bone SPECT scintigraphy. SPECT scans were repeated 1 year postoperatively and included static as well as dynamic phases. All scans were performed using 20 mCi of the radiopharmaceutical technetium-99m methylene diphosphonate. At 3 hours after injection, scinti-images were obtained using a Siemens dual-headed ROTA camera at 6-degree increments until the mandible had been evaluated for a total of 360 degrees [9]. These images were stored in 64 • 64 pixel frames on a Siemens computer system (VAX 11/750). Scan results were correlated with bone graft biopsy performed at the time of plate fixator removal, as well as physical examination. RESULTS Patients studied within this series could be categorized into three groups. Group 1 featured three patients who underwent mandibular reconstruction into a nonirradiated recipient bed. Group 2 consisted of four patients who underwent preoperative radiotherapy to the recipient mandibular bed prior to secondary mandibular reconstruction. Finally, both patients in Group 3 underwent immediate mandibular reconstruction followed by radiotherapy to the recipient bed as well as to the vascularized iliac crest graft (Table I). At 48 hours postoperatively, eight of nine SPECT scans were noted to have enhanced activity within the
THE AMERICAN JOURNAL OF SURGERY
VOLUME 160 OCTOBER 1990
399
LUKASH ET AL
TABLE I
Vascularized lilac Crest Bone Grafts for Mandibular Reconstruction in Nine Patients
Group 1
Diagnosis SCC SCC Blast injury
2
SCC Osteogenic sarcoma SCC SCC
3
SCC SCC
Extirpative Procedure
Mandibular Reconstruction
Preoperative Radiotherapy*
SPECT Scan 48 hrs
Postoperative Radiotherapy
SPECT Scan 1 yr
Hemimandibulectorny Segmental mandibulectomy Angle-to-angle defect Angle-to-angle mandibulectomy Hemimandibulectomy
Secondary Secondary
---
+ -I-
---
+ Jr
Normal Normal
Yes Yes
Secondary
--
Jr
--
+
Normal
Yes
Secondary
Jr
-I-
--
+
Normal
Yes
Secondary
Jr
Jr
--
Jr
Normal
Yes
Hemimandibulectomy Segmental mandibulectomy Angle-to-angle mandibulectomy Arch mar~ibulectomy
Secondary Secondary
-IJr
-I--
---
Jr Jr/--
Normal Accelular
No No
immediate
--
+
Jr
+
Normal
No
Immediate
--
+
Jr
--
Acellular
No
Bone Biopsy
Osseointegration
* Plus signs indicate "hot" scans; minus signs indicate "cold" scans. SCC = squamous cell carcinoma.
Figure 1. SPECT scan at 4 8 hours reveals enhanced vascularized graft activity.
vascularized graft relative to the surrounding calvarium, suggesting anastomotic patency. One "cold" scan, suggestive of early graft occlusion, was observed 48 hours postoperatively. Seven of the original "hot" scans continued to exhibit elevated mean activity ratios (MAR) at 1 year after reconstruction. The cold SPECT scan observed at 1 year postoperatively occurred in a patient who had undergone immediate reconstruction followed by radiotherapy. These findings are consistent with obliterative endarteritis secondary to radiotherapy and were confirmed by bone graft biopsy, which revealed sclerotic bone. Clinical evaluation revealed a fibrous union of this patient's mandibular graft. 400
THE AMERICAN JOURNAL OF SURGERY
Figure 2. SPECT scan at I year postoperatively reveals enhancement of vascularized graft despite post-reconstructive radiotherap y (6,000 rad).
Perhaps most important were the SPECT scan findings observed in a patient who also had undergone immediate mandibular reconstruction. This patient was noted to have a high degree of activity (MAR) on the SPECT scan at 1 year postoperatively, despite having undergone radiotherapy to the recipient bed and vascularized graft (Figures 1 and 2). The viability of this metabolically active, albeit irradiated, graft was confirmed by bone
VOLUME 160
OCTOBER 1990
VASCULARIZED BONE GRAFT FOR MANDIBULAR RECONSTRUCTION
graft biopsy. To date, this patient remains edentulous because of fear of osteoradionecrosis. Thus far, five patients have successfully undergone implant osseointegration, and now maintain a fixed osteo-dental prosthesis. COMMENTS Since its description by Taylor [1], the vascularized iliac crest composite graft has become a mainstay of mandibular reconstruction. As experience with this technique has accumulated, the creation of a fixed osteodental prosthesis through the utilization of implant osseointegration techniques has become possible [2,3]. Despite these advances, however, little information exists regarding the long-term characteristics of the vascularized iliac crest graft. This study demonstrates the successful application of bone S P E C T scintigraphy for purposes of noninvasively evaluating the long-term viability of vascularized iliac crest grafts used for mandibular reconstruction. Furthermore, it appears that such grafts maintain an enhanced level of metabolic activity on a long-term basis, making this graft suitable for implant osseointegration and functional mandibular reconstruction utilizing a fixed osteodental unit. Such findings were observed in those patients who featured a "hostile" environment secondary to preoperative radiotherapy to the recipient mandibular bed, in addition to those patients who were never treated with radiotherapy. Finally, bone SPECT scintigraphy may be useful in identifying select patients who have not experienced the
deleterious effects of radiotherapy to the vascularized bone graft. Such patients may ultimately prove to be suitable candidates for the mandibular graft stresses associated with a fixed osteo-dental prosthesis and thereby benefit from a truly functional masticatory process.
REFERENCES 1. Taylor GI. Reconstruction of the mandible with free composite iliac bone grafts. Ann Plast Surg 1982; 9: 361-76. 2. Lukash FN, Sachs SA. Functional mandibular reconstruction: prevention of the oral invalid. Plast Reconstr Surg 1989; 84: 22733. 3. Lukash RN, Sachs SA, Fischman B, Attie JN. Osseointegrated denture in a vascularized bone transfer: functional jaw reconstruction. Ann Plast Surg 1987; 19: 538-44. 4. Arata MA, Wood MB, Cooney WP IlL Revascularizedsegmental diaphysealbone transfers in the canine: an analysisof viability. J Reconstr Microsurg 1984; 1: 11-9. 5. Bos KE. Bone scintigraphy of experimental composite bone grafts revascularizedby microvascularanastomoses.Plast Reconstr Surg 1979; 64: 353-60. 6. Berggren A, Weiland A J, Ostrup LT. Bone scintigraphy in evaluating the viability of composite bone grafts revascularized by microvascular anastomoses, conventional autogenous bone grafts, and free non-revascularized periosteal grafts. J Bone Joint Surg 1982; 64: 799-809. 7. Yaremchuk M J, May JW. Correspondence. J Bone Joint Surg 1983; 65: 279-80. 8. Myers M J, Fazio F. The case for emission computed tomography with a rotating gamma camera. Appl Radiol 1981; 10:127-34. 9. MoskowitzGW, Lukash FN. Evaluation of bone graft viability. Semin Nucl Med 1988; 18: 246-54.
THE AMERICAN JOURNAL OFSURGERY
VOLUME 160 OCTOBER 1990 401