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The anatomical basis of the vascularized pronator quadratus pedicled bone graft
T H E A N A T O M I C A L B A S I S OF T H E V A S C U L A R I Z E D PRONATOR QUADRATUS PEDICLED BONE GRAFT J. C-H. LEE, J. LIM and P. B. CHACHA
From the Toa Payoh Hospital, Singapore The vascular supply of the pronator quadratus was studied in 25 cadaveric dissections following coloured latex injections. This showed that the main blood supply of the pronator quadratus came from the anterior interosseous artery. There was, however, a rich anastomosis between the branches of the anterior interosseous artery and those of the radial and ulnar arteries. It was possible to raise a corticocancellous bone graft from the anterior surface of the radial styloid on a pedicle of the lower fibres of the pronator quadratus muscle. This muscle pedicle had a constant branch of the anterior interosseous artery which vascularized the bone graft. Such a vascularized pedicled bone graft may be useful in the treatment of non-union of the scaphoid and Kienb6ck's disease.
Journal of Hand Surgery (British and European Volume, 1997) 22B: 5:644-646 The pronator quadratus pedicled bone graft harvested from the flexor surface of the most distal part of the radial styloid process was independently designed and described by Braun (1983) and Chacha (1984) for nonunion of the scaphoid and avascular necrosis of the lunate. Since then, further modification of the grafting technique has been reported by Kawai and Yamamoto (1988) who used this graft successfully in clinical cases. Leung and Hung (1990) described a similar vascularized bone graft based on a pedicle of the pronator quadratus but raised from the ulnar border of the radius. Brash (1955) noted that the blood supply of the pronator quadratus was from the anterior interosseous artery. Braun (1983) confirmed this finding and also noted the numerous microvascular connections within the muscle substance. The presence of these microvascular connections led Braun (1983) and Chacha (1984), in independent studies, to raise a pedicled bone graft based on the pronator quadratus muscle. The aim of this study was to determine whether, in addition to these microvascular connections, there was a constant vessel in this pedicle to maintain viability.
separate the graft and a subperiosteal dissection was carried out to ensure that the graft was not detached from the pronator quadratus pedicle. The muscle was dissected proximally and diagonally towards the ulna to ensure a pedicle width of at least 2 cm distally and 4 cm proximally at its base (Fig 1). The blood supply to the pronator quadratus and the pedicle supplying the graft was noted and documented by photography. The graft was then removed for microscopic examination to demonstrate the presence of dye in the bone. In four specimens, we tried to elevate the bone graft as described above and then cannulate, in sequential specimens, either the brachial, or the radial, or the ulnar or the anterior interosseous arteries. Coloured latex was then injected to try to demonstrate the blood supply to the bone graft. These attempts failed due to the copious leaking of the dye and soiling of the whole dissection field. These four specimens were excluded, thus leaving a total of 21 specimens for the study.
METHODS AND MATERIALS
Twenty-five fresh cadaveric upper limbs were used for the study, in ten specimens, the brachial artery was cannulated and injected with coloured latex after flushing with 10% formalin. Overflow into the venous system was prevented by making incisions in the finger tips. The specimens were then stored and refrigerated for 4 to 7 days. They were then thawed and dissected to identify the main vessels and their branches supplying the pronator quadratus and the distal end of the radius. In another 11 specimens, the brachial artery was similarly cannulated and injected with coloured latex after flushing with 10% formalin. In these specimens, the pronator quadratus was dissected with its vascular supply intact. A bone graft measuring 1.5 x 1.0 x 1.0 cm was raised from the anterior cortex of the radial styloid. The intended size of the graft was first marked with fine drill holes. A narrow sharp osteotome was then used to
Fig 1
644
The bone graft raised on the pedicle of the pronator quadratus. The anterior interosseous artery is shown by the arrow labelled "INTEROSSEOUS". The black arrow marked "a" shows the constant branch arising from the anterior interosseous artery traversing the pedicle (marked between the red arrows) and piercing the bone graft.
PRONATOR QUADRATUS PEDICLED BONE GRAFT
645
RESULTS Dye studies In all the 21 specimens, the studies showed that the pronator quadratus received its blood supply mainly from the anterior interosseous artery (Fig 2). There were contributions from the radial and ulnar arteries and these three arteries formed a very rich anastomotic network. At the distal one-third of the radius in 13 specimens, the radial artery gave off five branches perpendicular to its longitudinal axis to the pronator quadratus muscle. In eight specimens, it gave off six such branches (Fig 2). These branches had an average length of 14 mm and were given off at 1 cm intervals. After they pierced the pronator quadratus muscle, they anastomosed with the branches of the ulnar and the anterior interosseous arteries. In three specimens, the most distal branch was noted to pass transversely through the pronator quadratus and send branches to the wrist joint capsule before anastomosing with a branch from the ulnar artery. In one specimen, there was a direct anastomosis between the third branch and a branch of the anterior interosseous artery. In 15 specimens, the ulnar artery gave off one branch perpendicular to its longitudinal axis and bifurcated 1 cm distally into the proximal limb which pierced the muscle to anastomose directly with a branch of the anterior interosseous artery forming a loop (Fig 2). In the other six specimens more than one branch came off at irregular intervals and anastomosed with the branches of the anterior interosseous artery within the substance of the pronator quadratus. In all the 21 injected specimens, as the anterior interosseous artery passed into the substance of the pronator quadratus, it gave off tree-like branches about 1 to 2 cm from the proximal edge of the muscle. On average, 12 branches were given off before it ended at the level of the wrist joint (Fig 2). Each of the 12 branches divided several times into other branches and anastomosed richly with the branches of the radial and ulnar arteries. The bone graft raised on the pronator quadratus pedicle was found to receive its blood supply from a constant branch arising from the anterior interosseous artery. This branch was given off about 2 cm from the proximal edge of the pronator quadratus muscle. In all the 11 specimens in which the graft was raised on its pronator quadratus pedicle, this branch arising from the anterior interosseous artery could be seen travelling within the substance of the pronator quadratus muscle before finally piercing into the periosteum of the bone graft (Figs 1 and 3).
Microscopic studies Histological section of the bone graft was performed in seven specimens, stained with haematoxylin and eosin and examined under 10 x magnification. The vessels in
Fig 2
The three main arteries supplying the pronator quadratus muscle. The black arrow marked "a" shows one of the branches given perpendicularly from the radial artery. The black arrow marked "b" shows a branch of the ulnar artery before it bifurcates into further branches. The white arrow marked "c" shows the anterior interosseous artery.
the marrow spaces were stained with the dye (Fig 4). It would appear that the constant branch from the anterior interosseous artery was responsible for maintaining the blood flow into the bone graft. DISCUSSION Vascularized live bone grafts have been used as viable osteogenic tissue to revascularize non-unions and avascular necrosis since 1884 (Chacha, 1984). In the wrist, problems of scaphoid non-union and Kienb6ck's disease are common in clinical practice. Conventional methods of bone grafting for non-union of the scaphoid have a success rate of about 80 to 90% (Carrozzella et al, 1989; Cooney et al, 1980; Russe, 1960). In failed cases, the gradual and inevitable progression towards radiocarpal and intercarpal arthritis has led to the search for a live
Fig 3
The bone graft raised on the pedicle (arrow marked "p") seen end-on at lOx magnification. The three black arrows show the stained vessels in the bone graft. The constant branch of the anterior interosseous artery is seen to pierce the periosteum of the bone graft marked by arrow "a".
THE JOURNAL OF HAND SURGERY VOL. 22B No. 5 OCTOBER 1997
646
In clinical practice, the limitation of such a bone graft raised on a pedicle is the mobility of the graft which is dependent on the length of the pedicle. Chacha (1984) and Braun (1983) facilitated the rotation of the pedicle by removing the fascia overlying the pronator quadratus and then flexing the wrist to 30° and pronating the forearm to 45 °. Kawai and Yamamoto (1988) further improved the mobility by dissecting the ulnar origin of the pronator quadratus subperiosteally from the ulna and then doing a release. If by these above measures the pedicle cannot be rotated without excessive tension, perhaps a shallow trough made in the anterior cortex of the distal radius may help to accommodate the pedicle and increase its excursion. Fig 4
Vessels (arrows m a r k e d "v") s t a i n e d w i t h dye in the m a r r o w spaces o f the b o n e graft ( H a e m a t o x y l i n a n d eosin, x l 0 ) .
bone graft raised on a pedicle of the pronator quadratus muscle to revascularize the scaphoid and promote union. Although a rich network of vessels from the anterior interosseous, radial and ulnar arteries was found to supply the pronator quadratus, our studies showed that there is a constant branch from the anterior interosseous artery which traverses and supplies the pronator quadratus muscle before piercing the flexor surface of the radial styloid process from where the pedicled graft is raised. Although it was not possible to cannulate and inject the dye in the anterior interosseous artery after raising the pedicled graft to prove that the constant branch of the artery was the main source of blood supply to the bone graft, microscopic studies showed the presence of the dye staining the vascular channels in the graft. It is thus possible that the bone graft received its blood supply from this constant branch arising from the anterior interosseous artery. Based on this evidence, careful preservation of this constant branch from the anterior interosseous artery in the pedicle of the graft during the operation would be important to maintain the viability of the graft. Whether the microscopic blood flow into the graft remains uninterrupted after the operation in clinical cases has yet to be proved.
Acknowledgements We wish to express our sincere appreciation to Mr Robert Ng and Ms IC Song at the Experimental Surgery Unit, Singapore General Hospital for their invaluable and tireless assistance in the conduct of this study. We would also like to thank Professor Chao Tzee Cheng of the Department of Forensic Pathology and Professor Tan Set Kiat, Head of the Experimental Surgery Unit, Singapore General Hospital for their help and for access to the cadaver studies.
References Brash J C. Neurovascular hila of limb muscles. Edinburgh, E & S Livingstone, 1955: 21. Braun R M (1983). Pronator quadratus pedicle bone grafting in the forearm and proximal carpal row. Journal of Hand Surgery, 8: 612-613. Carrozzella J C, Stern P J, Murdock P A (1989). The fate of failed bone graft surgery for scaphoid non-unions. Journal of Hand Surgery, 14A: 800-806. Chacha P B (1984). Vascularised pedicular bone grafts. International Orthopaedics (SICOT), 8:117~138. Cooney W P, Dobyns J H, Linscheid R L (1980). Non-union of the scaphoid: Analysis of the results from bone grafting. Journal of Hand Surgery, 5: 343 354. Kawai H, Yamamoto K (1988). Pronator quadratus pedicled bone graft for old scaphoid fractures. Journal of Bone and Joint Surgery, 70B: 829-831. Leung P C, Hung L K (1990). Use of the pronator quadratus bone flap in bony reconstruction around the wrist. Journal of Hand Surgery, 15A: 637 640. Russe O (1960). Fracture of the carpal navicular: diagnosis, non-operative treatment and operative treatment. Journal of Bone and Joint Surgery, 42A: 759-768. Received:24 August 1995 Accepted after revision: 17 February 1997 Dr J. C-H. Lee,Toa Payoh Hospital, Toa Payoh Rise, Singapore1129. © 1997The British Societyfor Surgeryof the Hand
From the Toa Payoh Hospital, Singapore The vascular supply of the pronator quadratus was studied in 25 cadaveric dissections following coloured latex injections. This showed that the main blood supply of the pronator quadratus came from the anterior interosseous artery. There was, however, a rich anastomosis between the branches of the anterior interosseous artery and those of the radial and ulnar arteries. It was possible to raise a corticocancellous bone graft from the anterior surface of the radial styloid on a pedicle of the lower fibres of the pronator quadratus muscle. This muscle pedicle had a constant branch of the anterior interosseous artery which vascularized the bone graft. Such a vascularized pedicled bone graft may be useful in the treatment of non-union of the scaphoid and Kienb6ck's disease.
Journal of Hand Surgery (British and European Volume, 1997) 22B: 5:644-646 The pronator quadratus pedicled bone graft harvested from the flexor surface of the most distal part of the radial styloid process was independently designed and described by Braun (1983) and Chacha (1984) for nonunion of the scaphoid and avascular necrosis of the lunate. Since then, further modification of the grafting technique has been reported by Kawai and Yamamoto (1988) who used this graft successfully in clinical cases. Leung and Hung (1990) described a similar vascularized bone graft based on a pedicle of the pronator quadratus but raised from the ulnar border of the radius. Brash (1955) noted that the blood supply of the pronator quadratus was from the anterior interosseous artery. Braun (1983) confirmed this finding and also noted the numerous microvascular connections within the muscle substance. The presence of these microvascular connections led Braun (1983) and Chacha (1984), in independent studies, to raise a pedicled bone graft based on the pronator quadratus muscle. The aim of this study was to determine whether, in addition to these microvascular connections, there was a constant vessel in this pedicle to maintain viability.
separate the graft and a subperiosteal dissection was carried out to ensure that the graft was not detached from the pronator quadratus pedicle. The muscle was dissected proximally and diagonally towards the ulna to ensure a pedicle width of at least 2 cm distally and 4 cm proximally at its base (Fig 1). The blood supply to the pronator quadratus and the pedicle supplying the graft was noted and documented by photography. The graft was then removed for microscopic examination to demonstrate the presence of dye in the bone. In four specimens, we tried to elevate the bone graft as described above and then cannulate, in sequential specimens, either the brachial, or the radial, or the ulnar or the anterior interosseous arteries. Coloured latex was then injected to try to demonstrate the blood supply to the bone graft. These attempts failed due to the copious leaking of the dye and soiling of the whole dissection field. These four specimens were excluded, thus leaving a total of 21 specimens for the study.
METHODS AND MATERIALS
Twenty-five fresh cadaveric upper limbs were used for the study, in ten specimens, the brachial artery was cannulated and injected with coloured latex after flushing with 10% formalin. Overflow into the venous system was prevented by making incisions in the finger tips. The specimens were then stored and refrigerated for 4 to 7 days. They were then thawed and dissected to identify the main vessels and their branches supplying the pronator quadratus and the distal end of the radius. In another 11 specimens, the brachial artery was similarly cannulated and injected with coloured latex after flushing with 10% formalin. In these specimens, the pronator quadratus was dissected with its vascular supply intact. A bone graft measuring 1.5 x 1.0 x 1.0 cm was raised from the anterior cortex of the radial styloid. The intended size of the graft was first marked with fine drill holes. A narrow sharp osteotome was then used to
Fig 1
644
The bone graft raised on the pedicle of the pronator quadratus. The anterior interosseous artery is shown by the arrow labelled "INTEROSSEOUS". The black arrow marked "a" shows the constant branch arising from the anterior interosseous artery traversing the pedicle (marked between the red arrows) and piercing the bone graft.
PRONATOR QUADRATUS PEDICLED BONE GRAFT
645
RESULTS Dye studies In all the 21 specimens, the studies showed that the pronator quadratus received its blood supply mainly from the anterior interosseous artery (Fig 2). There were contributions from the radial and ulnar arteries and these three arteries formed a very rich anastomotic network. At the distal one-third of the radius in 13 specimens, the radial artery gave off five branches perpendicular to its longitudinal axis to the pronator quadratus muscle. In eight specimens, it gave off six such branches (Fig 2). These branches had an average length of 14 mm and were given off at 1 cm intervals. After they pierced the pronator quadratus muscle, they anastomosed with the branches of the ulnar and the anterior interosseous arteries. In three specimens, the most distal branch was noted to pass transversely through the pronator quadratus and send branches to the wrist joint capsule before anastomosing with a branch from the ulnar artery. In one specimen, there was a direct anastomosis between the third branch and a branch of the anterior interosseous artery. In 15 specimens, the ulnar artery gave off one branch perpendicular to its longitudinal axis and bifurcated 1 cm distally into the proximal limb which pierced the muscle to anastomose directly with a branch of the anterior interosseous artery forming a loop (Fig 2). In the other six specimens more than one branch came off at irregular intervals and anastomosed with the branches of the anterior interosseous artery within the substance of the pronator quadratus. In all the 21 injected specimens, as the anterior interosseous artery passed into the substance of the pronator quadratus, it gave off tree-like branches about 1 to 2 cm from the proximal edge of the muscle. On average, 12 branches were given off before it ended at the level of the wrist joint (Fig 2). Each of the 12 branches divided several times into other branches and anastomosed richly with the branches of the radial and ulnar arteries. The bone graft raised on the pronator quadratus pedicle was found to receive its blood supply from a constant branch arising from the anterior interosseous artery. This branch was given off about 2 cm from the proximal edge of the pronator quadratus muscle. In all the 11 specimens in which the graft was raised on its pronator quadratus pedicle, this branch arising from the anterior interosseous artery could be seen travelling within the substance of the pronator quadratus muscle before finally piercing into the periosteum of the bone graft (Figs 1 and 3).
Microscopic studies Histological section of the bone graft was performed in seven specimens, stained with haematoxylin and eosin and examined under 10 x magnification. The vessels in
Fig 2
The three main arteries supplying the pronator quadratus muscle. The black arrow marked "a" shows one of the branches given perpendicularly from the radial artery. The black arrow marked "b" shows a branch of the ulnar artery before it bifurcates into further branches. The white arrow marked "c" shows the anterior interosseous artery.
the marrow spaces were stained with the dye (Fig 4). It would appear that the constant branch from the anterior interosseous artery was responsible for maintaining the blood flow into the bone graft. DISCUSSION Vascularized live bone grafts have been used as viable osteogenic tissue to revascularize non-unions and avascular necrosis since 1884 (Chacha, 1984). In the wrist, problems of scaphoid non-union and Kienb6ck's disease are common in clinical practice. Conventional methods of bone grafting for non-union of the scaphoid have a success rate of about 80 to 90% (Carrozzella et al, 1989; Cooney et al, 1980; Russe, 1960). In failed cases, the gradual and inevitable progression towards radiocarpal and intercarpal arthritis has led to the search for a live
Fig 3
The bone graft raised on the pedicle (arrow marked "p") seen end-on at lOx magnification. The three black arrows show the stained vessels in the bone graft. The constant branch of the anterior interosseous artery is seen to pierce the periosteum of the bone graft marked by arrow "a".
THE JOURNAL OF HAND SURGERY VOL. 22B No. 5 OCTOBER 1997
646
In clinical practice, the limitation of such a bone graft raised on a pedicle is the mobility of the graft which is dependent on the length of the pedicle. Chacha (1984) and Braun (1983) facilitated the rotation of the pedicle by removing the fascia overlying the pronator quadratus and then flexing the wrist to 30° and pronating the forearm to 45 °. Kawai and Yamamoto (1988) further improved the mobility by dissecting the ulnar origin of the pronator quadratus subperiosteally from the ulna and then doing a release. If by these above measures the pedicle cannot be rotated without excessive tension, perhaps a shallow trough made in the anterior cortex of the distal radius may help to accommodate the pedicle and increase its excursion. Fig 4
Vessels (arrows m a r k e d "v") s t a i n e d w i t h dye in the m a r r o w spaces o f the b o n e graft ( H a e m a t o x y l i n a n d eosin, x l 0 ) .
bone graft raised on a pedicle of the pronator quadratus muscle to revascularize the scaphoid and promote union. Although a rich network of vessels from the anterior interosseous, radial and ulnar arteries was found to supply the pronator quadratus, our studies showed that there is a constant branch from the anterior interosseous artery which traverses and supplies the pronator quadratus muscle before piercing the flexor surface of the radial styloid process from where the pedicled graft is raised. Although it was not possible to cannulate and inject the dye in the anterior interosseous artery after raising the pedicled graft to prove that the constant branch of the artery was the main source of blood supply to the bone graft, microscopic studies showed the presence of the dye staining the vascular channels in the graft. It is thus possible that the bone graft received its blood supply from this constant branch arising from the anterior interosseous artery. Based on this evidence, careful preservation of this constant branch from the anterior interosseous artery in the pedicle of the graft during the operation would be important to maintain the viability of the graft. Whether the microscopic blood flow into the graft remains uninterrupted after the operation in clinical cases has yet to be proved.
Acknowledgements We wish to express our sincere appreciation to Mr Robert Ng and Ms IC Song at the Experimental Surgery Unit, Singapore General Hospital for their invaluable and tireless assistance in the conduct of this study. We would also like to thank Professor Chao Tzee Cheng of the Department of Forensic Pathology and Professor Tan Set Kiat, Head of the Experimental Surgery Unit, Singapore General Hospital for their help and for access to the cadaver studies.
References Brash J C. Neurovascular hila of limb muscles. Edinburgh, E & S Livingstone, 1955: 21. Braun R M (1983). Pronator quadratus pedicle bone grafting in the forearm and proximal carpal row. Journal of Hand Surgery, 8: 612-613. Carrozzella J C, Stern P J, Murdock P A (1989). The fate of failed bone graft surgery for scaphoid non-unions. Journal of Hand Surgery, 14A: 800-806. Chacha P B (1984). Vascularised pedicular bone grafts. International Orthopaedics (SICOT), 8:117~138. Cooney W P, Dobyns J H, Linscheid R L (1980). Non-union of the scaphoid: Analysis of the results from bone grafting. Journal of Hand Surgery, 5: 343 354. Kawai H, Yamamoto K (1988). Pronator quadratus pedicled bone graft for old scaphoid fractures. Journal of Bone and Joint Surgery, 70B: 829-831. Leung P C, Hung L K (1990). Use of the pronator quadratus bone flap in bony reconstruction around the wrist. Journal of Hand Surgery, 15A: 637 640. Russe O (1960). Fracture of the carpal navicular: diagnosis, non-operative treatment and operative treatment. Journal of Bone and Joint Surgery, 42A: 759-768. Received:24 August 1995 Accepted after revision: 17 February 1997 Dr J. C-H. Lee,Toa Payoh Hospital, Toa Payoh Rise, Singapore1129. © 1997The British Societyfor Surgeryof the Hand