Proximal radius exposure may be acquired by either the dorsal or volar approach depending on surgical requirements. The dorsal approach is traditionally recommended for fracture fixation of the proximal radius because of theoretically improved exposure and because the dorsal aspect of the bone is the tensile surface. The posterior interosseous nerve can be visualized and protected using this approach. The volar approach is preferred for biceps repair and boasts a distal extensile approach with adequate soft tissue coverage. Impingement on the bicipital tuberosity and biceps tendon, in addition to positioning on the compression side of the bone, makes the anterior or anterolateral position for plate placement less desirable.
The goal of this study was to quantify and compare in a cadaver model the area of bone exposed using both approaches. We hypothesized that equivalent exposures can be obtained and the posterior interosseous nerve can be identified with either the Thompson or Henry approach. Standard dorsal and volar approaches were performed on 10 fresh-frozen adult cadaveric upper-limb specimens. Cross-sectional area of exposure was quantified from digital photographs using software. The 2 approaches did not result in a significant difference in area exposed. Depending on case requirements, either the dorsal or volar approach will provide adequate exposure to the proximal radius.
Exposure of the proximal radius may be accomplished by either the volar or dorsal approach. Approaches to the proximal radius are necessary for a variety of reasons, including fracture fixation, treatment of nonunion or delayed union, tumor biopsy and treatment, osteomyelitis treatment, repair of bicipital tuberosity, nerve exploration, and radial osteotomy.1 Proximal forearm fractures represent 5% of fractures yearly.2 Diaphyseal fractures of the radius occur in 50% of proximal forearm fractures or 2.5% of all fractures yearly.2
The posterior or dorsal approach to the proximal radius was first described by Thompson3 in 1918. This approach is traditionally recommended for fracture fixation of the proximal radius because of theoretically improved exposure and because the dorsal aspect of the bone is the tensile surface.1 The posterior interosseous nerve can be visualized and protected using this approach; however, it is at risk, as proximal posterior plate placement may be irritating to the nerve. In the event that plate removal becomes necessary, it may be difficult to sufficiently isolate and protect the posterior interosseous nerve through scar.4 Furthermore, Spinner5 reported that the posterior interosseous nerve is located directly adjacent to the radial neck in 25% of patients, putting the nerve at risk of entrapment under a plate if fracture fixation requires proximal plate positioning. The interval between the extensor carpi radialus brevis and the extensor digitorum communis may also be technically difficult to develop proximally.4
The anterior or volar approach to the proximal radius was first described by Henry6 in 1927. It is preferred for biceps repair and boasts a distal extensile approach with adequate soft tissue coverage. Impingement on the bicipital tuberosity and biceps tendon, in addition to positioning on the compression side of the bone, makes the anterior or anterolateral position for plate placement less desirable.6 The posterior interosseous nerve may be at risk during this approach, and tension on the nerve during retraction of the supinator may cause a neuropraxia. In the quarter of the population where the nerve lies posteriorly juxtaposed to the radial neck, retractor placement during the anterior approach can compress the nerve against the bone.1
The surgeon must understand the advantages and disadvantages of each approach to ensure proper exposure (Table 1). While the Thompson approach has traditionally been recommended to provide the most adequate exposure, there may be times when it is advantageous to perform the Henry approach instead. The goal of this study was to quantify and compare area and identify pertinent anatomical landmarks of both approaches to the proximal radius using a cadaver model. We hypothesized that equivalent exposures can be obtained and the posterior interosseous nerve can be identified with either the Thompson or Henry approach. To our knowledge, quantitative studies of surface area of bone exposed for these approaches have not yet been described in the literature.
Materials and Methods
Following protocol approved by our Institutional Review Board, 20 exposures to the proximal radius were performed in 10 fresh-frozen adult cadaveric upper-limb specimens. None of the specimens had evidence of previous surgery or trauma about the elbow or forearm. Dorsal and volar approaches were performed sequentially so that there were 10 specimens in each exposure group, and each specimen served as its own control. All procedures were performed by a board-certified orthopedic surgeon (A.E.J.) or under his direct supervision by 1 of the co-authors (J.D.C., J.A.W.). All dissections were limited to 8 cm distal to the radiocapitellar joint, which represented roughly the broad pronator teres origin. Approaches were performed on each specimen in the following manner.
The Thompson Approach
The arm specimen was placed in the prone position. An incision was made starting anterior to the lateral epicondyle extending to Listers tubercle. The deep facia was then incised between the extensor carpi radialis brevis and the extensor digitorum communis. Next, the posterior interosseous nerve was identified exiting the supinator between its superficial and deep heads. The posterior interosseous nerve was then dissected out proximal to distal, identifying and preserving the motor branches. The arm was then supinated and the supinator muscle detached from the anterior aspect of the radius. The distance was measured from the radiocapitellar joint to the point where the posterior interosseous nerve crossed the center of the radius from the surgeons view (Figures 1, 2).
|Figure 1: Dissection of the Thompson approach. Abbreviations: ECRB, extensor carpi radialis brevis; EDC, extensor digitorum communis; PIN, posterior interosseous nerve. |
|Figure 2: The interval for the Thompson exposure is between the extensor carpi radialis brevis and the extensor digitorum communis. The posterior interosseous nerve can be identified exiting the supinator between its superficial and deep heads. Abbreviations: ECRB, extensor carpi radialis brevis; EDC, extensor digitorum communis; PIN, posterior interosseous nerve. |
The Henry Approach
The arm specimen was placed in the supine position. An incision was made from the styloid process of radius to the lateral epicondyle of the humerus. The internervous plane between the brachioradialis and the pronator teres was developed. The superficial radial nerve was identified and retracted radially with the brachioradialis. Lateral to the biceps tendon, the supinator was located with the posterior interosseous nerve within the muscle. The supinator insertion was then incised off the anterior aspect of the radius subperiosteally for adequate visualization of the field. The distance was measured from the radiocapitellar joint to the point where the posterior interosseous nerve crossed the center of the radius from the surgeons view (Figures 3, 4).
|Figure 3: Dissection of the Henry approach. Abbreviation: FCR, flexor carpi radialis. |
|Figure 4: The interval for the Henry approach is between the brachioradialis and the pronator teres. The posterior interosseous nerve lies within the supinator and can be protected by incising the muscle off the anterior aspect of the radius subperiosteally for adequate visualization of the field. Abbreviation: FCR, flexor carpi radialis. |
Dissection was carried to the radiocapitellar joint, and 1 end of a hand-held caliper was placed into the center of the joint. The posterior interosseous nerve was identified at the point where it crosses the mid-portion of bone from the surgeons perspective. The caliper then measured the distance along the radius from the center of the radiocapitaller joint to the posterior interosseous nerve. The posterior interosseous nerve was then dissected out to verify location either adjacent to the proximal radius or within the supinator muscle after each approach.
Standard surgical retractors were used to demonstrate maximal exposure of the radius. Digital pictures were taken perpendicular to the dissection and analyzed using the computer software program ImageJ (National Institutes of Health, Bethesda, Maryland). This computer program compared a known distance (ie, a metric ruler in each image) to the actual number of pixels to calculate the square area of exposed proximal radius. Data for each approach were analyzed and compared for average square area and average distances from the radiocapitaller joint to the posterior interosseous nerve using paired t tests and Bland-Altmon plots. Correlations between the measurements and the specimen demographics were sought using paired t tests.
Average specimen age was 73.3 years (range, 57-86 years). Average donor body mass index (BMI) was 24.1 kg/m2 (range, 19-32 kg/m2) (Table 2). There were 9 right and 1 left upper extremities. The average square area exposed by the Thompson approach was 7.31±1.54 cm2. The average square area exposed by the Henry approach was 6.37±1.29 cm2. There was no statistical difference between the average exposed areas (P=.173) (Table 3).
In all 20 approaches, the posterior interosseous nerve and radiocapitellar joint were easily identified. During the Thompson approach, the posterior interosseous nerve was located on average 3.3±1.49 cm from the radiocapitellar joint, and the shortest distance measured with the forearm in neutral rotation was 0.6 cm. During the Henry approach, the posterior interosseous nerve was located on average 2.8±1.54 cm from the center of the radiocapitellar joint, and the shortest distance measured with the forearm in neutral rotation was also 0.6 cm. The distance of the posterior interosseous nerve from the radiocapitellar joint in either dissection was not statistically significant (P=.409). The posterior interosseous nerve was adjacent to the proximal radius in 2 of the 10 specimens. We also easily identified the lateral epicondyle during the Thompson approach and the biceps tendon during the Henry approach.
Neither the length of the specimen nor the height of the donor correlated with the distance measured from the radiocapitellar joint to the posterior interosseous nerve. Likewise, the area exposed for each approach did not correlate with the donors sex, BMI, or height (P>.05).
For internal fixation, safe access to the proximal radius is accomplished by appropriate knowledge of the advantages and disadvantages of each approach. Our study demonstrates that one may confidently perform a dorsal or volar approach and be assured that the same amount of proximal radius exposure as well as visualization of the posterior interosseous nerve is possible.
Some authors have recommended 1 approach over the other in certain circumstances. With preexisting wrist extensor injury, the Thompson approach may not be desired due to potential extensor digitorum communis paralysis. This injury causes a sign of horns deformity due to inability to extend middle and ring fingers.7
Mekhail et al8 suggested that the Henry approach is the safest and recommended lateral plating from this approach to avoid impingement on the biceps tendon. They also warned against plate removal through the posterior approach due to the risk of prior scar making posterior interosseous nerve identification difficult.8 Tornetta et al9 advised that plate placement on the proximal radius does not require an extensile approach anteriorly or posteriorly because nerve entrapment is unlikely; however, nerve traction could occur with any approach.
Other authors have focused on how best to protect the posterior interosseous nerve using either approach. Elgafy et al10 identified and mapped the 6 branches of the posterior interosseous nerve to safely navigate the Thompson approach. The patterns of innervation described by Elgafy et al10 are consistent with the observations in our study. Strauch et al11 and Tubbs et al12 have suggested the use of more superficial anatomical landmarks to help predict the deep location of the posterior interosseous nerve, using the bicipital tuberosity and the lateral epicondyle, respectively.
Our data are consistent with the observations of posterior interosseous nerve location versus the radial tuberosity reported by Strauch et al.11 Elgafy et al,13 in another report, emphasized how best to protect the posterior interosseous nerve during dissection posteriorly. The observations in that study located the posterior interosseous nerve a longer distance from the radiocapitellar joint than in our study; however, our measurements reflect the nerves position as it crosses the surgical field on the bone rather than the nerves emergence from the supinator, a point more distal. These reports are important guides for decreasing iatrogenic injury during fracture fixation and prudent exposure.
Our study validates previous studies that measured the distance of the posterior interosseous nerve from other anatomical landmarks.9,13 We also demonstrated a similar frequency of the posterior interosseous nerve lying directly adjacent to the radial neck, originally described as occurring 25% of the time.5 However, our data represent the first comparative quantification of exposure afforded by the Thompson and Henry approaches to the proximal radius. We also verified that both exposures allow other important landmarks such as the biceps tendon insertion to be easily visualized. Because many surgeons are more familiar with the Henry approach, we recommend this approach if it meets the needs of the specific case. Our study validates that this approach can be performed safely with regard to the posterior interosseous nerve and that exposure of the proximal radius is adequate.
Our study has several limitations. The relatively small number of cadavers available may not have allowed us to demonstrate a difference in exposure area due to being underpowered. Although this study uses advanced digital imaging software, it is limited by the fact that a 2-dimentional image is attempting to represent a 3-dimentional surface. Our images were taken from the perspective of the surgeons view, directly perpendicular to the exposure. While the surgeons view may be a weakness of the study, it may also underestimate the true surface area exposed since simple manipulation of retractors may provide even more surface exposure.
Area of exposed bone and distance of the posterior interosseous nerve from the radiocapitellar joint are not statistically different when the proximal radius is exposed using either the Thompson approach or the Henry approach. Therefore, either approach is sufficient and should be chosen based on thorough knowledge of the posterior interosseous nerve anatomy and the surgeons need for best addressing the patients injury.
- Hoppenfeld S, deBoer P, Buckley R. The forearm. In: Surgical Exposures in Orthopaedics: the Anatomic Approach. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:147-181.
- Court-Brown CM, Caesar B. Epidemiology of adult fractures: a review [published online ahead of print June 30, 2006]. Injury. 2006; 37(8):691-697.
- Thompson JE. Anatomical methods of approach in operations on the long bones or extremities. Ann Surg. 1918; 68(3):309-329.
- 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.
- Spinner M. Injuries to the Major Branches of Peripheral Nerves of the Forearm. 2nd ed. Philadelphia, PA: WB Saunders; 1978.
- Henry AK. Complete exposure of the radius. In: Exposures of Long Bones and Other Surgical Methods. Bristol, England: John Wright & Sons Ltd; 1927:9-12.
- Spinner RJ, Berger RA, Carmichael SW, Dyck PJ, Nunley JA. Isolated paralysis of the extensor digitorum communis associated with the posterior (Thompson) approach to the proximal radius. J Hand Surg Am. 1998; 23(1):135-141.
- Mekhail AO, Ebraheim NA, Jackson WT, Yeasting RA. Anatomic considerations for the anterior exposure of the proximal portion of the radius. J Hand Surg Am. 1996; 21(5):794-801.
- Tornetta P III, Hochwald N, Bono C, Grossman M. Anatomy of the posterior interosseous nerve in relation to fixation of the radial head. Clin Orthop Relat Res. 1997; (345):215-218.
- Elgafy H, Ebraheim NA, Rezcallah AT, Yeasting RA. Posterior interosseous nerve terminal branches. Clin Orthop Relat Res. 2000; (376):242-251.
- Strauch RJ, Rosenwasser MP, Glazer PA. Surgical exposure of the dorsal proximal third of the radius: how vulnerable is the posterior interosseous nerve? J Shoulder Elbow Surg. 1996; 5(5):342-346.
- Tubbs RS, Salter EG, Wellons JC III, Blount JP, Oakes WJ. Superficial surgical landmarks for identifying the posterior interosseous nerve. J Neurosurg. 2006; 104(5):796-799.
- Elgafy H, Ebraheim NA, Yeasting RA. Extensile posterior approach to the radius. Clin Orthop Relat Res. 2000; (373):252-258.
Drs Cross, White, Johnson, Blair, and Hsu are from Brooke Army Medical Center, Fort Sam Houston, Texas.
Drs Cross, White, Johnson, Blair, and Hsu have no relevant financial relationships to disclose.
This study was conducted under a research protocol approved by the US Army Institute of Surgical Research and Brooke Army Medical Center Institutional Review Board.
The views expressed in this article are those of the authors and should not be construed as official policy of the Department of the Army, the Department of Defense, or the United States government.
Correspondence should be addressed to: Jessica D. Cross, MD, 3851 Roger Brooke Dr, Fort Sam Houston, TX 78234 (email@example.com).