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Extensile Surgical Exposures of the Radius: A Comparative Anatomic Study
SCIENTIFIC ARTICLE
Extensile Surgical Exposures of the Radius: A Comparative Anatomic Study Christopher R. Jockel, MD, Dan A. Zlotolow, MD, R. Bryan Butler, MD, Edward H. Becker, MD
Purpose To evaluate and compare exposures of the radius using 3 surgical approaches. Our hypotheses were that the anterior flexor carpi radialis approach allows greater exposure of the distal radius than does the volar-ulnar approach, and the extensile flexor carpi radialis approach allows comparable proximal and midshaft exposure of the radius compared with the dorsal Thompson approach. Methods We performed anterior and dorsal exposures of the radius on 10 matched pairs of cadavers (20 forearms) randomly assigned to 1 anterior and 1 dorsal approach. We measured and compared the anatomic features and limits of the anterior flexor carpi radialis approach, volar-ulnar approach to the distal radius, and the dorsal Thompson approach. Results The anterior flexor carpi radialis approach exposed 3.3 cm of distal radius width, was convertible to an extensile approach proximally, required sacrifice of 3 arterial branches, and was limited by the junction of the radial and ulnar arteries. This approach provided 79% of radius exposure and ended 4.7 cm distal to the radiocapitellar joint. The volar-ulnar approach to the distal radius exposed 3.1 cm of distal radius width. The dorsal Thompson approach sacrificed no arterial branches, provided 69% of radius exposure, was limited by the first compartment distally and the posterior interosseous nerve proximally, and ended within 2.6 cm of the radiocapitellar joint. The posterior interosseous nerve coursed 19, 14, and 6 mm dorsolateral to the distal, middle, and proximal margins, respectively, of the supinator insertion on the radius. Conclusions The volar-ulnar approach provided less access to the radial styloid and was not as extensile as the flexor carpi radialis approach. The Thompson approach provided more proximal exposure than the flexor carpi radialis approach. Clinical relevance Improved knowledge of the anatomy, limits of exposure, and comparison of features between approaches to the radius may facilitate surgical planning and exposure. (J Hand Surg 2013;38A:745–752. Copyright © 2013 by the American Society for Surgery of the Hand. All rights reserved.) Key words Radius, anterior flexor carpi radialis approach, volar-ulnar distal radius approach, dorsal Thompson approach. ULTIPLE SURGICAL APPROACHES have been described for exposure of the radius. In 1918, Thompson1 described an extensile dorsal approach to the radius using the interval between the wrist
M
From the Colorado Permanente Medical Group, Denver, CO; Shriners Hospital for Children, Philadelphia, PA; the Ohio State University Upper Extremity Service, Columbus, OH; and the Department of Orthopaedics, University of Maryland, Baltimore, MD. Received for publication September 26, 2012; accepted in revised form December 14, 2012. The authors thank Dori Kelly, MA, University of Maryland School of Medicine, for expert assistance with the manuscript.
extensors and the finger extensors. Subsequently, Henry2 described an extensile anterior approach to the radius using the interval between the pronator teres and brachioradialis proximally and the flexor carpi radialis D.A. Z. is a paid consultant or receives royalties from Osteomed, Arthrex Inc, and Elsevier. Corresponding author: Christopher R. Jockel, MD, Colorado Permanente Medical Group, 2045 Franklin Street, Denver, CO 80205; e-mail: [email protected]. 0363-5023/13/38A04-0017$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2012.12.029
© ASSH 䉬 Published by Elsevier, Inc. All rights reserved. 䉬 745
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FIGURE 1: Anterior ulna-sided distal radius approach. Access to the distal radioulnar joint, the pronator quadratus (PQ), and the retracted flexor pollicis longus (FPL) can be seen.
and brachioradialis distally. A volar-ulnar approach to the distal radius can also be used for exposure, using the interval between the finger flexors and the ulnar neurovascular bundle and flexor carpi ulnaris. Recently, the anterior flexor carpi radialis approach for fractures of the distal radius has been popularized by Orbay et al.3 This approach is similar to the volar Henry approach but uses the floor of the flexor carpi radialis tendon sheath as the interval for deep dissection rather than the interval between the radial artery and brachioradialis. With the flexor carpi radialis approach, the radial artery is therefore retracted radially, whereas the Henry approach mobilizes the radial artery ulnarly. This distinction between exposures is important to consider when choosing the most appropriate extensile surgical approach to the radius. Whereas the classic Henry approach can be extended proximally to the elbow if the radial artery is mobilized ulnarly and the recurrent leash is sacrificed, the extensile flexor carpi radialis approach is limited by the junction of the radial and ulnar arteries in the proximal forearm. The purpose of this study was to evaluate exposures of the radius by comparing the flexor carpi radialis, Thompson, and volar-ulnar approaches. Our goal was to define the relevant surgical anatomy, quantify limits of exposure, and compare features of each approach. We hypothesized that the flexor carpi radialis approach allows greater exposure of the distal radius than does the volar-ulnar approach, and that the extensile flexor carpi radialis approach allows equivalent proximal and mid-shaft exposure of the radius compared with the dorsal Thompson approach.
MATERIALS AND METHODS We dissected 10 matched pairs of cadaveric upper limbs (20 forearms) to evaluate exposure of the radius using 3 surgical approaches. In 1 randomly selected forearm from each pair, we performed an anterior flexor carpi radialis approach, an extensile flexor carpi radialis approach, and a dorsal Thompson approach to the radius. In the matched forearm, we performed a volarulnar approach to the distal radius and a dorsal Thompson approach to the radius. We obtained measurements using a digital caliper to assess the extent of surgical exposure and quantify the location of anatomic landmarks during each approach. To evaluate exposure of the distal radius using the anterior flexor carpi radialis and volar-ulnar approaches, we measured the width of the distal radius exposed and the distance from the radiocarpal joint line at the scapholunate interval to the distal aspect of the flexor pollicis longus origin without elevating the muscle (Fig. 1). We also measured the distance from the joint line to the proximal edge of the pronator quadratus. We then assessed exposure of the radius throughout the length of the forearm using the extensile flexor carpi radialis approach and the dorsal Thompson approach. For the extensile flexor carpi radialis approach, we measured the distance from the radiocarpal joint line to the insertion of the pronator teres, to the insertion of the supinator, and recorded the number of arterial branches sacrificed during proximal exposure. We also measured the distance from the radiocarpal joint line to the junction of the radial and ulnar arteries that limits the
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FIGURE 2: Exposed radius from an extensile anterior flexor carpi radialis approach. Elevation of the pronator quadratus (PQ), flexor pollicis longus (FPL) and flexor digitorum superficialis (FDS), pronator teres (PT), and supinator (Sup) muscles can be seen. Also shown are the ulnar artery (U ART), radial artery (R ART), and watershed line (WS).
FIGURE 3: Exposed radius from a dorsal Thompson approach. The first extensor compartment containing the abductor pollicis longus (APL) and extensor pollicis brevis (EPB), the wrist extensors extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL), the insertion of the pronator teres (PT), the footprint of the supinator (Sup) elevated dorsolaterally, and the posterior interosseous nerve (PIN) are shown.
exposure of the radius proximally through the extensile flexor carpi radialis approach (Fig. 2). For the dorsal Thompson approach to the forearm, we measured the distance from the radiocarpal joint line to the first extensor compartment (abductor pollicis longus, extensor pollicis brevis), to the pronator teres insertion, to the supinator insertion, and to the proximal extent of the exposure where the posterior interosseous nerve courses across the radial neck. We further measured the location of the posterior interosseous nerve within the supinator at the proximal, middle, and distal portions of the muscle perpendicular to the anterior margin where it is elevated from the radius. We then measured the total exposure of the radius in 2 ways. First, we measured the distance from the radiocarpal
joint line to the posterior interosseous nerve proximally. Second, we determined the distance between the proximal aspect of the first extensor compartment and the posterior interosseous nerve, considering that during surgery the first compartment would not be routinely sacrificed or have hardware placed deep to it because of concerns of potential tendon irritation, adhesion, or attritional injury (Fig. 3). We also noted the number of arterial branches that were sacrificed. We measured the total length of each radius from the radiocarpal joint line at the scapholunate interval to the radiocapitellar joint. The distance of each noted structure from the radiocarpal joint was further expressed as a percentage of the entire length of the radius.
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We compared the approaches and the exposures of the radius using the means, standard deviations, and a paired Student t-test to quantify the relevant anatomical features. Statistical significance was set at P ⬍ .050. Anterior flexor carpi radialis and extensile flexor carpi radialis approaches We made an 8-cm longitudinal incision from the wrist flexion crease extending proximally along the radial edge of the flexor carpi radialis tendon. Dissection was carried down to the floor of the flexor carpi radialis tendon sheath, which was incised on the radial margin to avoid injuring the palmar cutaneous branch of the median nerve. We then bluntly developed the space of Parona between the pronator quadratus and the finger flexors with the radial artery retracted radially. The pronator quadratus insertion was reflected from its radial margin to expose the radius. For the extensile approach, we continued the skin incision proximally toward the radial tuberosity. Dissection was carried down between the pronator teres and the brachioradialis superficially and the supinator deeply as in the classic anterior Henry approach. We then mobilized the supinator laterally to expose the radius. The radius was exposed up to the junction of the radial and ulnar arteries proximally. Volar-ulnar distal radius approach We made an 8-cm longitudinal skin incision ulnar to the palmaris longus and continued dissection down to the pronator quadratus in the interval between the finger flexors and the flexor carpi ulnaris and ulnar neurovascular bundle. We then divided the pronator quadratus over the radial aspect of the distal radius and elevated it subperiosteally as for the flexor carpi radialis approach.4 Dorsal Thompson approach Distally, we extended a midline dorsal longitudinal incision just ulnar to the Lister tubercle proximally toward the lateral epicondyle. Dissection was continued down to the extensor retinaculum with care taken to preserve dorsal veins. We achieved radius exposure by releasing the third extensor compartment, mobilizing the extensor pollicis longus, and incising the floor of the compartment. The fourth compartment was elevated subperiosteally without compromising the origin of the dorsal radiocarpal ligament and the dorsal capsule. The second extensor compartment can also be elevated subperiosteally if more radial exposure is needed. Proximally, dissection proceeded between the extensor carpi radialis brevis and extensor digitorum com-
munis tendons. We identified the interval just proximal to the crossing abductor pollicis longus and extensor pollicis brevis with distinct fascial planes. The muscle fibers of the extensor digitorum communis partially originate from the fascia of the mobile wad and must be released to continue the dissection proximally. Deep dissection to the radius involves releasing the fibers of the supinator muscle from the radius lateral to the posterior interosseous nerve with the forearm in supination. RESULTS The volar-ulnar approach exposed a mean length of 6.5 ⫾ 0.6 cm and the flexor carpi radialis approach exposed a mean length of 6.7 ⫾ 1 cm of the distal radius up to the flexor pollicis longus origin, respectively. These amounts represented 27% and 28% of the mean total length of the radius, which measured 24.4 cm. The flexor carpi radialis approach allowed more exposure of the width of the distal radius at the watershed line (3.3 ⫾ 0.3 cm) compared with the anterior ulna-sided distal radius approach (3.1 ⫾ 0.3 cm) (P ⫽ .019) (Fig. 4). Both approaches allowed access to the volar-ulnar corner of the radius, whereas the flexor carpi radialis approach provided additional exposure of the radial column. The flexor carpi radialis approach could be extended proximally, sacrificing a mean of 2.9 ⫾ 1 branches of the radial artery. This extensile approach was limited proximally by the junction of the radial and ulnar arteries and provided a mean of 19.2 ⫾ 1.4 cm (79%) of total radius exposure. The junction of the radial and ulnar arteries was on average 4.7 ⫾ 1.7 cm distal to the radiocapitellar joint (Fig. 5). The dorsal Thompson approach provided a mean total exposure of 21.9 ⫾ 1.9 cm (90%) of the radius measured from the radiocarpal joint line to the posterior interosseous nerve, and a mean of 16.9 ⫾ 1.8 cm (69%) of radius exposure from the proximal aspect of the first extensor compartment to the posterior interosseous nerve. No arterial branches were sacrificed during this approach. The posterior interosseous nerve was located a mean of 2.6 ⫾ 0.8 cm distal to the radiocapitellar joint and was the limit to proximal exposure (Fig. 6). The posterior interosseous nerve coursed dorsolaterally in the supinator a mean of 19.3 ⫾ 2.8, 14.2 ⫾ 1.9, and 5.8 ⫾ 1.5 mm perpendicular to the anterior margin of the muscle at the distal, middle, and proximal insertion, respectively, on the radius (Fig. 7). With the extensile flexor carpi radialis approach, the distance from the radiocarpal joint line
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FIGURE 4: Difference in width of exposure of the distal radius (3.3 versus 3.1 cm for the flexor carpi radialis and the ulnar approaches, respectively), distance from the joint line of the proximal margin of the pronator quadratus (5.1 cm), and distal aspect of the flexor pollicis longus origin (6.6 cm). Courtesy of Dan A. Zlotolow, MD.
FIGURE 5: Limit of exposure of the extensile flexor carpi radialis approach. The approach provides 19.2 cm (79%) of the length of the radius, extending proximally to within 4.7 cm of the radiocapitellar joint at the junction of the radial and ulnar arteries. Courtesy of Dan A. Zlotolow, MD.
FIGURE 6: Clinically relevant limit of exposure of the dorsal Thompson approach from the first extensor compartment to the posterior interosseous nerve, providing 16.9 cm (69%) of the length of the radius. Courtesy of Dan A. Zlotolow, MD.
to the flexor pollicis longus, pronator teres, and supinator were on average 27%, 62%, and 71%, respectively, of the total length of the radius. All muscles required elevation from the volar radius to obtain proximal exposure. With the dorsal Thompson approach, the pronator teres and supinator were encountered at a mean of 49% and 56% of the length of the radius. This approach required no muscle elevation until reaching the distal aspect of
the supinator, because the broad tendinous portion of the pronator teres did not need to be released from the radius to obtain proximal exposure (Figs. 8, 9). DISCUSSION In this study, we compared exposures of the radius using the flexor carpi radialis, Thompson, and volar-
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FIGURE 7: Distances of the posterior interosseous nerve (PIN) from the leading edge of the supinator at the arcade of Frohse proximally (Prox.), middle of the supinator (Mid.), and distal margin. The posterior interosseous nerve diverges from the leading edge as it courses dorsoradially through the supinator.
FIGURE 8: Where the pronator quadratus (21%), flexor pollicis longus (27%), pronator teres (62%), and supinator (71%) are encountered during the extensile flexor carpi radialis approach, expressed as a percentage of the entire length of the radius. Courtesy of Dan A. Zlotolow, MD.
FIGURE 9: Where the pronator teres (49%) and supinator (56%) are encountered during the dorsal Thompson approach, expressed as a percentage of the entire length of the radius. Courtesy of Dan A. Zlotolow, MD.
ulnar approaches. Our goal was to define the relevant surgical anatomy, quantify limits of exposure, and compare features of each approach. Knowledge of these components is essential for planning the most appropriate surgical exposure.
There are limited studies comparing surgical approaches and exposures of the radius. Cross et al5 compared anterior and dorsal approaches to the proximal radius and found no significant difference in area exposed using the Thompson and Henry approaches.
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Several authors have advocated for the volar-ulnar approach to the distal radius. Bain et al4 describe this approach as “universal,” allowing access to the median nerve, ulnar nerve, carpus, flexor tendons, distal radioulnar joint, and distal radius. Nana et al6 also advocated for this approach but cautioned about the inability to address the radial column of the radius. Our findings agree with this report because the volar-ulnar approach exposed significantly less width of the distal radius at the watershed line compared with the flexor carpi radialis approach and provided limited exposure to the radial styloid. Therefore, if access to the distal radioulnar joint, central column of the radius, or ulna is needed during an approach to the distal radius, the volar-ulnar approach is a reasonable option. The flexor carpi radialis approach to the radius has become increasingly popular for addressing surgical issues of the distal radius and forearm.7,8 The limits and extensibility of this approach have not been previously defined. In our study, the flexor carpi radialis approach allowed exposure of the full width of the distal radius including the volar-ulnar corner with retraction of the flexor tendons and median nerve. It also provided access to 79% of the length of the radius. A mean of 3 arterial branches were sacrificed along with elevation of the volar musculature. The flexor carpi radialis approach is therefore an acceptable extensile exposure for visualizing the radius from the radiocarpal joint distally to within 4.7 cm of the radiocapitellar joint. The Thompson approach to the radius provides extensile dorsal exposure and is limited proximally by the posterior interosseous nerve.9 –11 Our data correlate with those presented by Elgafy et al9 and Mekhail et al,10 who found that the posterior interosseous nerve is located approximately 3 cm from the radiocapitellar joint. Pronation and supination of the radius, however, changes the location of the nerve within the surgical field and alters the safe zone of exposure.12 In our study, we measured the perpendicular distance of the posterior interosseous nerve from the anterior insertion of the supinator where it is released from the radius. This value should not change during rotation of the forearm and provides a constant reference for safely mobilizing the supinator. Our data complement those presented in other studies that show the posterior interosseous nerve exiting the supinator 67 mm from the radial head, 15 mm from the radial margin of the radius, and 3.8 cm distal to proximal margin of the supinator.13,14 With the posterior interosseous nerve 14 to 19 mm away, the surgeon should have confidence that the supinator insertion can be safely elevated from the
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radius to further extend this approach’s exposure with a low risk of direct injury to the nerve. Comparison of the flexor carpi radialis and Thompson approaches reveals the benefits and limitations of each exposure. In terms of technical difficulty, the Thompson approach required the sacrifice of no arterial branches and did not require the elevation of forearm musculature until reaching the distal supinator, and the radius remained relatively superficial throughout the exposure. Nevertheless, this approach requires the surgeon to protect the posterior interosseous nerve. In contrast, the extensile flexor carpi radialis approach requires the sacrifice of 3 arterial branches and elevation of volar musculature throughout the length of the forearm, and the radius rests deeper in the forearm musculature with proximal exposure. We do not believe that sacrificing these branches of the radial artery is clinically meaningful during the volar approach. As measured from the radiocarpal joint line, the dorsal Thompson approach allowed potentially greater mean total exposure of the radius (90%) compared with the extended flexor carpi radialis approach (79%). When measuring the exposure from the first extensor compartment to the posterior interosseous nerve proximally, however, the relevant exposure using the Thompson approach was 69% of the total length of the radius. The extensile flexor carpi radialis approach therefore exposed a functional length 2.3 cm (10%) more of the total radius than did the Thompson approach by allowing greater distal extension. In contrast, however, the Thompson approach allowed a mean of 2.1 cm more proximal exposure toward the radiocapitellar joint than the extensile anterior flexor carpi radialis approach (Figs. 5, 6). Knowledge of these features should assist with choosing the most appropriate surgical approach. There are several limitations to this cadaveric study. In randomly selecting the right or left forearm for either the flexor carpi radialis or the volar-ulnar approach to the distal radius, there were 4 left and 6 right forearms with the flexor carpi radialis approach, and 6 left and 4 right forearms with the volar-ulnar approach. We were also unaware of the hand dominance of the cadavers. These side-to-side differences between right and left forearms could contribute to subtle discrepancies in data. To standardize the surgical approaches to the distal radius, we limited the length of the skin incision to 8 cm for the flexor carpi radialis and the volar-ulnar approaches. Furthermore, we attempted to use retractors without excess tension on the median nerve while measuring the width of distal radius exposure. We realize
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that the operating surgeon may choose to obtain additional exposure of the radius by extending the incision, further releasing deep structures, and by vigilant use of retractors. REFERENCES 1. Thompson JE. Anatomical methods of approach in operations on the long bones of the extremities. Ann Surg. 1918;68(3):309 –329. 2. Henry AK. Complete exposure of the radius. Br J Surg. 1926;13(51): 506 –508. 3. Orbay JL, Badia A, Indriago IR, et al. The extended flexor carpi radialis approach: a new perspective for the distal radius fracture. Tech Hand Up Extrem Surg. 2001;5(4):204 –211. 4. Bain GI, Pourgiezis N, Roth JH. Surgical approaches to the distal radioulnar joint. Tech Hand Up Extrem Surg. 2007;11(1):51–56. 5. Cross JD, White JA, Johnson AE, Blair JA, Hsu JR. Comparison of dorsal and volar approaches to the proximal radius. Orthopedics. 2011;34(2):93. 6. Nana AD, Joshi A, Lichtman DA. Plating of the distal radius. J Am Acad Orthop Surg. 2005;13(3):159 –171. 7. Lattman T, Dietrich M, Meier C, Kilgus M, Platz A. Comparison of 2 surgical approaches for volar locking plate osteosynthesis of the distal radius. J Hand Surg Am. 2008;33(7):1135–1143.
8. Wijffels MM, Orbay JL, Infriago I, Ring D. The extended flexor carpi radialis approach for partially healed malaligned fractures of the distal radius. Injury. 2012;43(7):1204 –1208. 9. Elgafy H, Ebraheim NA, Yeasting RA. Extensile posterior approach to the radius. Clin Orthop Relat Res. 2000;(373):252– 258. 10. Mekhail AO, Ebraheim NA, Jackson WT, Yeasting RA. Vulnerability of the posterior interosseous nerve during proximal radius exposures. Clin Orthop Relat Res. 1995;(315):199 –208. 11. Schimizzi A, MacLennan A, Meier KM, Chia B, Catalano LW III, Glickel SZ. Defining a safe zone of dissection during the extensor digitorum communis splitting approach to the proximal radius and forearm: an anatomic study. J Hand Surg Am. 2009;34(7):1252– 1255. 12. Diliberti T, Botte MJ, Abrams RA. Anatomical considerations regarding the posterior interosseous nerve during posterolateral approaches to the proximal part of the radius. J Bone Joint Surg Am. 2000;82(6):809 – 813. 13. Thomas SJ, Yakin DE, Parry BR, Lubahn JD. The anatomical relationship between the posterior interosseous nerve and the supinator muscle. J Hand Surg Am. 2000;25(5):936 –941. 14. Ebraheim NA, Jin F, Pulisetti D, Yeasting RA. Quantitative anatomical study of the posterior interosseous nerve. Am J Orthop. 2000; 29(9):702–704.
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Extensile Surgical Exposures of the Radius: A Comparative Anatomic Study Christopher R. Jockel, MD, Dan A. Zlotolow, MD, R. Bryan Butler, MD, Edward H. Becker, MD
Purpose To evaluate and compare exposures of the radius using 3 surgical approaches. Our hypotheses were that the anterior flexor carpi radialis approach allows greater exposure of the distal radius than does the volar-ulnar approach, and the extensile flexor carpi radialis approach allows comparable proximal and midshaft exposure of the radius compared with the dorsal Thompson approach. Methods We performed anterior and dorsal exposures of the radius on 10 matched pairs of cadavers (20 forearms) randomly assigned to 1 anterior and 1 dorsal approach. We measured and compared the anatomic features and limits of the anterior flexor carpi radialis approach, volar-ulnar approach to the distal radius, and the dorsal Thompson approach. Results The anterior flexor carpi radialis approach exposed 3.3 cm of distal radius width, was convertible to an extensile approach proximally, required sacrifice of 3 arterial branches, and was limited by the junction of the radial and ulnar arteries. This approach provided 79% of radius exposure and ended 4.7 cm distal to the radiocapitellar joint. The volar-ulnar approach to the distal radius exposed 3.1 cm of distal radius width. The dorsal Thompson approach sacrificed no arterial branches, provided 69% of radius exposure, was limited by the first compartment distally and the posterior interosseous nerve proximally, and ended within 2.6 cm of the radiocapitellar joint. The posterior interosseous nerve coursed 19, 14, and 6 mm dorsolateral to the distal, middle, and proximal margins, respectively, of the supinator insertion on the radius. Conclusions The volar-ulnar approach provided less access to the radial styloid and was not as extensile as the flexor carpi radialis approach. The Thompson approach provided more proximal exposure than the flexor carpi radialis approach. Clinical relevance Improved knowledge of the anatomy, limits of exposure, and comparison of features between approaches to the radius may facilitate surgical planning and exposure. (J Hand Surg 2013;38A:745–752. Copyright © 2013 by the American Society for Surgery of the Hand. All rights reserved.) Key words Radius, anterior flexor carpi radialis approach, volar-ulnar distal radius approach, dorsal Thompson approach. ULTIPLE SURGICAL APPROACHES have been described for exposure of the radius. In 1918, Thompson1 described an extensile dorsal approach to the radius using the interval between the wrist
M
From the Colorado Permanente Medical Group, Denver, CO; Shriners Hospital for Children, Philadelphia, PA; the Ohio State University Upper Extremity Service, Columbus, OH; and the Department of Orthopaedics, University of Maryland, Baltimore, MD. Received for publication September 26, 2012; accepted in revised form December 14, 2012. The authors thank Dori Kelly, MA, University of Maryland School of Medicine, for expert assistance with the manuscript.
extensors and the finger extensors. Subsequently, Henry2 described an extensile anterior approach to the radius using the interval between the pronator teres and brachioradialis proximally and the flexor carpi radialis D.A. Z. is a paid consultant or receives royalties from Osteomed, Arthrex Inc, and Elsevier. Corresponding author: Christopher R. Jockel, MD, Colorado Permanente Medical Group, 2045 Franklin Street, Denver, CO 80205; e-mail: [email protected]. 0363-5023/13/38A04-0017$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2012.12.029
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FIGURE 1: Anterior ulna-sided distal radius approach. Access to the distal radioulnar joint, the pronator quadratus (PQ), and the retracted flexor pollicis longus (FPL) can be seen.
and brachioradialis distally. A volar-ulnar approach to the distal radius can also be used for exposure, using the interval between the finger flexors and the ulnar neurovascular bundle and flexor carpi ulnaris. Recently, the anterior flexor carpi radialis approach for fractures of the distal radius has been popularized by Orbay et al.3 This approach is similar to the volar Henry approach but uses the floor of the flexor carpi radialis tendon sheath as the interval for deep dissection rather than the interval between the radial artery and brachioradialis. With the flexor carpi radialis approach, the radial artery is therefore retracted radially, whereas the Henry approach mobilizes the radial artery ulnarly. This distinction between exposures is important to consider when choosing the most appropriate extensile surgical approach to the radius. Whereas the classic Henry approach can be extended proximally to the elbow if the radial artery is mobilized ulnarly and the recurrent leash is sacrificed, the extensile flexor carpi radialis approach is limited by the junction of the radial and ulnar arteries in the proximal forearm. The purpose of this study was to evaluate exposures of the radius by comparing the flexor carpi radialis, Thompson, and volar-ulnar approaches. Our goal was to define the relevant surgical anatomy, quantify limits of exposure, and compare features of each approach. We hypothesized that the flexor carpi radialis approach allows greater exposure of the distal radius than does the volar-ulnar approach, and that the extensile flexor carpi radialis approach allows equivalent proximal and mid-shaft exposure of the radius compared with the dorsal Thompson approach.
MATERIALS AND METHODS We dissected 10 matched pairs of cadaveric upper limbs (20 forearms) to evaluate exposure of the radius using 3 surgical approaches. In 1 randomly selected forearm from each pair, we performed an anterior flexor carpi radialis approach, an extensile flexor carpi radialis approach, and a dorsal Thompson approach to the radius. In the matched forearm, we performed a volarulnar approach to the distal radius and a dorsal Thompson approach to the radius. We obtained measurements using a digital caliper to assess the extent of surgical exposure and quantify the location of anatomic landmarks during each approach. To evaluate exposure of the distal radius using the anterior flexor carpi radialis and volar-ulnar approaches, we measured the width of the distal radius exposed and the distance from the radiocarpal joint line at the scapholunate interval to the distal aspect of the flexor pollicis longus origin without elevating the muscle (Fig. 1). We also measured the distance from the joint line to the proximal edge of the pronator quadratus. We then assessed exposure of the radius throughout the length of the forearm using the extensile flexor carpi radialis approach and the dorsal Thompson approach. For the extensile flexor carpi radialis approach, we measured the distance from the radiocarpal joint line to the insertion of the pronator teres, to the insertion of the supinator, and recorded the number of arterial branches sacrificed during proximal exposure. We also measured the distance from the radiocarpal joint line to the junction of the radial and ulnar arteries that limits the
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FIGURE 2: Exposed radius from an extensile anterior flexor carpi radialis approach. Elevation of the pronator quadratus (PQ), flexor pollicis longus (FPL) and flexor digitorum superficialis (FDS), pronator teres (PT), and supinator (Sup) muscles can be seen. Also shown are the ulnar artery (U ART), radial artery (R ART), and watershed line (WS).
FIGURE 3: Exposed radius from a dorsal Thompson approach. The first extensor compartment containing the abductor pollicis longus (APL) and extensor pollicis brevis (EPB), the wrist extensors extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL), the insertion of the pronator teres (PT), the footprint of the supinator (Sup) elevated dorsolaterally, and the posterior interosseous nerve (PIN) are shown.
exposure of the radius proximally through the extensile flexor carpi radialis approach (Fig. 2). For the dorsal Thompson approach to the forearm, we measured the distance from the radiocarpal joint line to the first extensor compartment (abductor pollicis longus, extensor pollicis brevis), to the pronator teres insertion, to the supinator insertion, and to the proximal extent of the exposure where the posterior interosseous nerve courses across the radial neck. We further measured the location of the posterior interosseous nerve within the supinator at the proximal, middle, and distal portions of the muscle perpendicular to the anterior margin where it is elevated from the radius. We then measured the total exposure of the radius in 2 ways. First, we measured the distance from the radiocarpal
joint line to the posterior interosseous nerve proximally. Second, we determined the distance between the proximal aspect of the first extensor compartment and the posterior interosseous nerve, considering that during surgery the first compartment would not be routinely sacrificed or have hardware placed deep to it because of concerns of potential tendon irritation, adhesion, or attritional injury (Fig. 3). We also noted the number of arterial branches that were sacrificed. We measured the total length of each radius from the radiocarpal joint line at the scapholunate interval to the radiocapitellar joint. The distance of each noted structure from the radiocarpal joint was further expressed as a percentage of the entire length of the radius.
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We compared the approaches and the exposures of the radius using the means, standard deviations, and a paired Student t-test to quantify the relevant anatomical features. Statistical significance was set at P ⬍ .050. Anterior flexor carpi radialis and extensile flexor carpi radialis approaches We made an 8-cm longitudinal incision from the wrist flexion crease extending proximally along the radial edge of the flexor carpi radialis tendon. Dissection was carried down to the floor of the flexor carpi radialis tendon sheath, which was incised on the radial margin to avoid injuring the palmar cutaneous branch of the median nerve. We then bluntly developed the space of Parona between the pronator quadratus and the finger flexors with the radial artery retracted radially. The pronator quadratus insertion was reflected from its radial margin to expose the radius. For the extensile approach, we continued the skin incision proximally toward the radial tuberosity. Dissection was carried down between the pronator teres and the brachioradialis superficially and the supinator deeply as in the classic anterior Henry approach. We then mobilized the supinator laterally to expose the radius. The radius was exposed up to the junction of the radial and ulnar arteries proximally. Volar-ulnar distal radius approach We made an 8-cm longitudinal skin incision ulnar to the palmaris longus and continued dissection down to the pronator quadratus in the interval between the finger flexors and the flexor carpi ulnaris and ulnar neurovascular bundle. We then divided the pronator quadratus over the radial aspect of the distal radius and elevated it subperiosteally as for the flexor carpi radialis approach.4 Dorsal Thompson approach Distally, we extended a midline dorsal longitudinal incision just ulnar to the Lister tubercle proximally toward the lateral epicondyle. Dissection was continued down to the extensor retinaculum with care taken to preserve dorsal veins. We achieved radius exposure by releasing the third extensor compartment, mobilizing the extensor pollicis longus, and incising the floor of the compartment. The fourth compartment was elevated subperiosteally without compromising the origin of the dorsal radiocarpal ligament and the dorsal capsule. The second extensor compartment can also be elevated subperiosteally if more radial exposure is needed. Proximally, dissection proceeded between the extensor carpi radialis brevis and extensor digitorum com-
munis tendons. We identified the interval just proximal to the crossing abductor pollicis longus and extensor pollicis brevis with distinct fascial planes. The muscle fibers of the extensor digitorum communis partially originate from the fascia of the mobile wad and must be released to continue the dissection proximally. Deep dissection to the radius involves releasing the fibers of the supinator muscle from the radius lateral to the posterior interosseous nerve with the forearm in supination. RESULTS The volar-ulnar approach exposed a mean length of 6.5 ⫾ 0.6 cm and the flexor carpi radialis approach exposed a mean length of 6.7 ⫾ 1 cm of the distal radius up to the flexor pollicis longus origin, respectively. These amounts represented 27% and 28% of the mean total length of the radius, which measured 24.4 cm. The flexor carpi radialis approach allowed more exposure of the width of the distal radius at the watershed line (3.3 ⫾ 0.3 cm) compared with the anterior ulna-sided distal radius approach (3.1 ⫾ 0.3 cm) (P ⫽ .019) (Fig. 4). Both approaches allowed access to the volar-ulnar corner of the radius, whereas the flexor carpi radialis approach provided additional exposure of the radial column. The flexor carpi radialis approach could be extended proximally, sacrificing a mean of 2.9 ⫾ 1 branches of the radial artery. This extensile approach was limited proximally by the junction of the radial and ulnar arteries and provided a mean of 19.2 ⫾ 1.4 cm (79%) of total radius exposure. The junction of the radial and ulnar arteries was on average 4.7 ⫾ 1.7 cm distal to the radiocapitellar joint (Fig. 5). The dorsal Thompson approach provided a mean total exposure of 21.9 ⫾ 1.9 cm (90%) of the radius measured from the radiocarpal joint line to the posterior interosseous nerve, and a mean of 16.9 ⫾ 1.8 cm (69%) of radius exposure from the proximal aspect of the first extensor compartment to the posterior interosseous nerve. No arterial branches were sacrificed during this approach. The posterior interosseous nerve was located a mean of 2.6 ⫾ 0.8 cm distal to the radiocapitellar joint and was the limit to proximal exposure (Fig. 6). The posterior interosseous nerve coursed dorsolaterally in the supinator a mean of 19.3 ⫾ 2.8, 14.2 ⫾ 1.9, and 5.8 ⫾ 1.5 mm perpendicular to the anterior margin of the muscle at the distal, middle, and proximal insertion, respectively, on the radius (Fig. 7). With the extensile flexor carpi radialis approach, the distance from the radiocarpal joint line
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FIGURE 4: Difference in width of exposure of the distal radius (3.3 versus 3.1 cm for the flexor carpi radialis and the ulnar approaches, respectively), distance from the joint line of the proximal margin of the pronator quadratus (5.1 cm), and distal aspect of the flexor pollicis longus origin (6.6 cm). Courtesy of Dan A. Zlotolow, MD.
FIGURE 5: Limit of exposure of the extensile flexor carpi radialis approach. The approach provides 19.2 cm (79%) of the length of the radius, extending proximally to within 4.7 cm of the radiocapitellar joint at the junction of the radial and ulnar arteries. Courtesy of Dan A. Zlotolow, MD.
FIGURE 6: Clinically relevant limit of exposure of the dorsal Thompson approach from the first extensor compartment to the posterior interosseous nerve, providing 16.9 cm (69%) of the length of the radius. Courtesy of Dan A. Zlotolow, MD.
to the flexor pollicis longus, pronator teres, and supinator were on average 27%, 62%, and 71%, respectively, of the total length of the radius. All muscles required elevation from the volar radius to obtain proximal exposure. With the dorsal Thompson approach, the pronator teres and supinator were encountered at a mean of 49% and 56% of the length of the radius. This approach required no muscle elevation until reaching the distal aspect of
the supinator, because the broad tendinous portion of the pronator teres did not need to be released from the radius to obtain proximal exposure (Figs. 8, 9). DISCUSSION In this study, we compared exposures of the radius using the flexor carpi radialis, Thompson, and volar-
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FIGURE 7: Distances of the posterior interosseous nerve (PIN) from the leading edge of the supinator at the arcade of Frohse proximally (Prox.), middle of the supinator (Mid.), and distal margin. The posterior interosseous nerve diverges from the leading edge as it courses dorsoradially through the supinator.
FIGURE 8: Where the pronator quadratus (21%), flexor pollicis longus (27%), pronator teres (62%), and supinator (71%) are encountered during the extensile flexor carpi radialis approach, expressed as a percentage of the entire length of the radius. Courtesy of Dan A. Zlotolow, MD.
FIGURE 9: Where the pronator teres (49%) and supinator (56%) are encountered during the dorsal Thompson approach, expressed as a percentage of the entire length of the radius. Courtesy of Dan A. Zlotolow, MD.
ulnar approaches. Our goal was to define the relevant surgical anatomy, quantify limits of exposure, and compare features of each approach. Knowledge of these components is essential for planning the most appropriate surgical exposure.
There are limited studies comparing surgical approaches and exposures of the radius. Cross et al5 compared anterior and dorsal approaches to the proximal radius and found no significant difference in area exposed using the Thompson and Henry approaches.
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Several authors have advocated for the volar-ulnar approach to the distal radius. Bain et al4 describe this approach as “universal,” allowing access to the median nerve, ulnar nerve, carpus, flexor tendons, distal radioulnar joint, and distal radius. Nana et al6 also advocated for this approach but cautioned about the inability to address the radial column of the radius. Our findings agree with this report because the volar-ulnar approach exposed significantly less width of the distal radius at the watershed line compared with the flexor carpi radialis approach and provided limited exposure to the radial styloid. Therefore, if access to the distal radioulnar joint, central column of the radius, or ulna is needed during an approach to the distal radius, the volar-ulnar approach is a reasonable option. The flexor carpi radialis approach to the radius has become increasingly popular for addressing surgical issues of the distal radius and forearm.7,8 The limits and extensibility of this approach have not been previously defined. In our study, the flexor carpi radialis approach allowed exposure of the full width of the distal radius including the volar-ulnar corner with retraction of the flexor tendons and median nerve. It also provided access to 79% of the length of the radius. A mean of 3 arterial branches were sacrificed along with elevation of the volar musculature. The flexor carpi radialis approach is therefore an acceptable extensile exposure for visualizing the radius from the radiocarpal joint distally to within 4.7 cm of the radiocapitellar joint. The Thompson approach to the radius provides extensile dorsal exposure and is limited proximally by the posterior interosseous nerve.9 –11 Our data correlate with those presented by Elgafy et al9 and Mekhail et al,10 who found that the posterior interosseous nerve is located approximately 3 cm from the radiocapitellar joint. Pronation and supination of the radius, however, changes the location of the nerve within the surgical field and alters the safe zone of exposure.12 In our study, we measured the perpendicular distance of the posterior interosseous nerve from the anterior insertion of the supinator where it is released from the radius. This value should not change during rotation of the forearm and provides a constant reference for safely mobilizing the supinator. Our data complement those presented in other studies that show the posterior interosseous nerve exiting the supinator 67 mm from the radial head, 15 mm from the radial margin of the radius, and 3.8 cm distal to proximal margin of the supinator.13,14 With the posterior interosseous nerve 14 to 19 mm away, the surgeon should have confidence that the supinator insertion can be safely elevated from the
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radius to further extend this approach’s exposure with a low risk of direct injury to the nerve. Comparison of the flexor carpi radialis and Thompson approaches reveals the benefits and limitations of each exposure. In terms of technical difficulty, the Thompson approach required the sacrifice of no arterial branches and did not require the elevation of forearm musculature until reaching the distal supinator, and the radius remained relatively superficial throughout the exposure. Nevertheless, this approach requires the surgeon to protect the posterior interosseous nerve. In contrast, the extensile flexor carpi radialis approach requires the sacrifice of 3 arterial branches and elevation of volar musculature throughout the length of the forearm, and the radius rests deeper in the forearm musculature with proximal exposure. We do not believe that sacrificing these branches of the radial artery is clinically meaningful during the volar approach. As measured from the radiocarpal joint line, the dorsal Thompson approach allowed potentially greater mean total exposure of the radius (90%) compared with the extended flexor carpi radialis approach (79%). When measuring the exposure from the first extensor compartment to the posterior interosseous nerve proximally, however, the relevant exposure using the Thompson approach was 69% of the total length of the radius. The extensile flexor carpi radialis approach therefore exposed a functional length 2.3 cm (10%) more of the total radius than did the Thompson approach by allowing greater distal extension. In contrast, however, the Thompson approach allowed a mean of 2.1 cm more proximal exposure toward the radiocapitellar joint than the extensile anterior flexor carpi radialis approach (Figs. 5, 6). Knowledge of these features should assist with choosing the most appropriate surgical approach. There are several limitations to this cadaveric study. In randomly selecting the right or left forearm for either the flexor carpi radialis or the volar-ulnar approach to the distal radius, there were 4 left and 6 right forearms with the flexor carpi radialis approach, and 6 left and 4 right forearms with the volar-ulnar approach. We were also unaware of the hand dominance of the cadavers. These side-to-side differences between right and left forearms could contribute to subtle discrepancies in data. To standardize the surgical approaches to the distal radius, we limited the length of the skin incision to 8 cm for the flexor carpi radialis and the volar-ulnar approaches. Furthermore, we attempted to use retractors without excess tension on the median nerve while measuring the width of distal radius exposure. We realize
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that the operating surgeon may choose to obtain additional exposure of the radius by extending the incision, further releasing deep structures, and by vigilant use of retractors. REFERENCES 1. Thompson JE. Anatomical methods of approach in operations on the long bones of the extremities. Ann Surg. 1918;68(3):309 –329. 2. Henry AK. Complete exposure of the radius. Br J Surg. 1926;13(51): 506 –508. 3. Orbay JL, Badia A, Indriago IR, et al. The extended flexor carpi radialis approach: a new perspective for the distal radius fracture. Tech Hand Up Extrem Surg. 2001;5(4):204 –211. 4. Bain GI, Pourgiezis N, Roth JH. Surgical approaches to the distal radioulnar joint. Tech Hand Up Extrem Surg. 2007;11(1):51–56. 5. Cross JD, White JA, Johnson AE, Blair JA, Hsu JR. Comparison of dorsal and volar approaches to the proximal radius. Orthopedics. 2011;34(2):93. 6. Nana AD, Joshi A, Lichtman DA. Plating of the distal radius. J Am Acad Orthop Surg. 2005;13(3):159 –171. 7. Lattman T, Dietrich M, Meier C, Kilgus M, Platz A. Comparison of 2 surgical approaches for volar locking plate osteosynthesis of the distal radius. J Hand Surg Am. 2008;33(7):1135–1143.
8. Wijffels MM, Orbay JL, Infriago I, Ring D. The extended flexor carpi radialis approach for partially healed malaligned fractures of the distal radius. Injury. 2012;43(7):1204 –1208. 9. Elgafy H, Ebraheim NA, Yeasting RA. Extensile posterior approach to the radius. Clin Orthop Relat Res. 2000;(373):252– 258. 10. Mekhail AO, Ebraheim NA, Jackson WT, Yeasting RA. Vulnerability of the posterior interosseous nerve during proximal radius exposures. Clin Orthop Relat Res. 1995;(315):199 –208. 11. Schimizzi A, MacLennan A, Meier KM, Chia B, Catalano LW III, Glickel SZ. Defining a safe zone of dissection during the extensor digitorum communis splitting approach to the proximal radius and forearm: an anatomic study. J Hand Surg Am. 2009;34(7):1252– 1255. 12. Diliberti T, Botte MJ, Abrams RA. Anatomical considerations regarding the posterior interosseous nerve during posterolateral approaches to the proximal part of the radius. J Bone Joint Surg Am. 2000;82(6):809 – 813. 13. Thomas SJ, Yakin DE, Parry BR, Lubahn JD. The anatomical relationship between the posterior interosseous nerve and the supinator muscle. J Hand Surg Am. 2000;25(5):936 –941. 14. Ebraheim NA, Jin F, Pulisetti D, Yeasting RA. Quantitative anatomical study of the posterior interosseous nerve. Am J Orthop. 2000; 29(9):702–704.
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