SCIENTIFIC ARTICLE

Dorsal Surgical Approaches to the Proximal Interphalangeal Joint: A Comparative Anatomic Study David H. Wei, MD, MS, Robert J. Strauch, MD

Purpose Adequate exposure of the articular surface of the head of the proximal phalanx is essential for reduction of intra-articular fractures of the proximal interphalangeal (PIP) joint. We compared the articular exposure obtained by a dorsal extensoretendon splitting (Swanson), an extensor tendonereflecting (Chamay), and an extensor mechanismesparing approach. Methods The PIP joints of 24 digits from 6 fresh-frozen cadaveric specimens were randomly assigned to 1 of 3 dorsal surgical exposures: an extensor tendonesplitting, extensor tendone reflecting, or extensor mechanismesparing approach. The exposed surface was painted with methylene blue and the PIP joints were disarticulated to reveal the distal articular surface of the proximal phalanx. Using 3-dimensional digital mapping, we calculated the percentage of the exposed dyed surface area to the total surface area and compared the 3 approaches. Results The mean percent exposed joint surface area for the extensor tendonesplitting, extensor tendonereflecting, and extensor mechanismesparing approaches were 41%, 52%, and 16%, respectively. Each approach provided a significantly different percentage of articular PIP joint surface area from the other 2. Conclusions The amount of articular surface visualized using 3 dorsal approaches to the PIP joint must be weighed against the amount of extensor mechanism violated. Exposure of the articular surface by the extensor mechanismesparing approach to the PIP joint allowed nearly a third of the exposure gained by the extensor tendonereflecting exposure. Although the extensor tendonereflecting technique revealed the greatest amount of surface, nearly 50% of the proximal phalanx articular surface remained inaccessible as long as the collateral ligaments were intact. Clinical relevance Understanding the limitations inherent in dorsal exposure of the PIP joint may help guide the surgical approach for the individual patient. (J Hand Surg Am. 2014;-:-e-. Copyright Ó 2014 by the American Society for Surgery of the Hand. All rights reserved.) Key words Proximal interphalangeal joint, surgical approach, articular exposure.

From the Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY. Received for publication October 7, 2013; accepted in revised form February 4, 2014. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Robert J. Strauch, MD, College of Physicians and Surgeons, Columbia University, 622 West 168th Street, PH-11-1119, New York, NY 10032; e-mail: [email protected]. 0363-5023/14/---0001$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2014.02.004

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visualization of the distal articular surface of the proximal phalanx are essential to facilitating anatomic reduction of articular fractures and proximal interphalangeal (PIP) joint fracture-dislocations. The ideal approach to the PIP joint would allow adequate visualization with complete preservation of the stabilizers to the joint and minimal violation of the traversing tendons. Many surgeons favor dorsal approaches because they spare the volar plate and collateral ligaments while DEQUATE EXPOSURE AND DIRECT

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avoiding dissection of the neurovascular bundles. Preservation of the central slip attachment is helpful in dorsal exposures to minimize postoperative PIP joint extensor lag and boutonniere deformity. We studied 3 dorsal surgical approaches that all preserve the central slip attachment: an extensor tendonesplitting approach proposed by Swanson,1 a dorsal extensor tendone reflecting approach recommended by Chamay,2 and an extensor mechanismesparing approach. We quantitatively compared each of these approaches by measuring the amount of articular cartilage exposed on the distal end of the proximal phalanx. Moreover, we hypothesized that visualization of the articular cartilage of the proximal phalangeal head is possible with the extensor mechanismesparing approach and that the volar articular cartilage remains hidden no matter the chosen dorsal approach when the collateral ligaments are intact. MATERIALS AND METHODS We studied 6 fresh-frozen adult cadaveric hand specimens: 3 right and 3 left hands. Each hand specimen was intact distal to the forearm and did not have apparent trauma, deformity, severe joint degeneration, or prior dissection. The individual PIP joints of the 24 available digits (excluding thumbs) were randomly assigned to 1 of 3 surgical approaches: extensor tendon splitting, extensor tendon reflecting, or extensor mechanism sparing. We used a stratified block randomization process such that each surgical approach would be performed an equal number of times. All exposures were performed through a longitudinal straight midline skin incision centered over the PIP joint, approximately 5 cm in length. Skin flaps were raised radially and ulnarly and retracted for complete exposure of the extensor mechanism. Each of the 24 PIP joints was then surgically approached as assigned in the manner originally described. The extensor tendonesplitting approach was performed by incising the central extensor tendon in the midline longitudinally from its insertion on the base of the middle phalanx to the midproximal phalanx level1 (Fig. 1). Although Swanson1 originally described releasing the central tendon completely from the base of the middle phalanx, for the purposes of our study, we did not release the central tendon from its insertion. Instead, the extensor tendon was simply split and allowed to subluxate laterally while the PIP joint was flexed to expose the distal articular surface of the proximal phalanx. The extensor tendon reflecting approach described by Chamay2 was performed by creating a V-shaped J Hand Surg Am.

FIGURE 1: Extensor tendonesplitting approach. A midline longitudinal incision is made through the extensor tendon without disruption of the insertion onto the base of the middle phalanx. The PIP joint is then maximally flexed, and the extensor tendon is allowed to subluxate laterally to expose the articular surface.

incision in the extensor mechanism with the base located distally to include the insertion of the central slip on the middle phalanx (Fig. 2). The length of the V-shaped incision was designed such that the acute point of the triangle was located at the junction of the proximal one third and distal two thirds of the proximal phalanx. Upon reflection of the distally based triangular flap, the lateral bands were allowed to subluxate palmarward to expose the PIP joint. The extensor mechanismesparing approach raises skin flaps to expose the lateral bands on either side of the PIP joint. The transverse retinacular ligament was then identified (Fig. 3) and incised on both sides of the extensor mechanism. This allowed the lateral bands to be elevated dorsally with the central tendon on either or both sides of the proximal phalanx such that the periosteum of the shaft was exposed along with the capsuloligamentous structures of the PIP joint. The extensor mechanism was left fully intact along with the insertion of the central slip, and the collateral ligaments were spared. Visualization of the head of the proximal phalanx was performed with radial and ulnar retraction and simultaneous elevation of the extensor mechanism. r

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FIGURE 3: Extensor mechanismesparing approach. The transverse retinacular ligament is A identified and B incised on either side of the extensor mechanism, just volar to the lateral bands. C The extensor mechanism is then elevated off the proximal phalanx, leaving the central slip intact and exposing the PIP joint. We completely removed the skin for illustrative purposes; this digit was not used for testing.

FIGURE 2: Extensor tendonereflecting approach. A A distally based tendinous triangular flap is created and B is reflected distally to reveal the articular surface with the PIP joint maximally flexed.

After each approach was performed, the articular surface of the head of the proximal phalanx was stained with methylene blue. This was accomplished by manipulating the PIP joint in flexion and extension to expose the greatest surface area. We then applied the dye to the exposed articular surface using a 0.05-mm tipped straight applicator that allowed accurate and precise coloration of all visible cartilage. The painted specimens were allowed to dry for 5 minutes. The PIP joints were then disarticulated, and the proximal phalanx was completely stripped of soft tissue. The articular surface of the proximal phalanx was then digitally mapped using a 3-dimensional digitizer (Microscribe 2GX; Solution Technologies, Oella, MD). Three-dimensional computer software (Rhino 3D; McNeel North America, Seattle, WA) was used to analyze and calculate surface areas of each specimen (Fig. 4). Each dyed and undyed area of each specimen was measured 3 times to ensure high precision and reproducibility. Statistical comparisons were performed using 3-way analysis of variance and paired Student t tests with Bonferroni correction. The P value was set at less than .050 for statistical significance.

and extensor mechanismesparing approaches were 41%, 52%, and 16%, respectively (Fig. 5). Each approach provided a significantly different percentage of articular PIP joint surface area from the other 2 (P < .050 for all comparisons). The total articular surface area of each digit was also calculated, with the index finger averaging 147 mm2, the middle finger, 148 mm2, the ring, 125 mm2, and the little finger, 94 mm2. Comparisons of total articular surface area among digits revealed 2 pairs of statistically significant differences. The surface areas of the distal end of the proximal phalanx of the index and middle fingers were both approximately 1.5 times as large as the little fingers (P ¼ .020 and P ¼ .008, respectively). DISCUSSION Adequate exposure and direct visualization of the articular surface are critical to the successful anatomic reduction and treatment of intra-articular condylar fractures of the proximal phalanx. We studied 3 dorsal approaches to the PIP joint that spare incision of the central slip and collateral ligaments, and thus avoid any need for reattachment of these structures. This minimizes postoperative imbalance and the vulnerability to adhesion formation. Although dorsal

RESULTS The mean percent exposed joint surface area for extensor tendonesplitting, extensor tendonereflecting, J Hand Surg Am.

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FIGURE 4: Three-dimensional digitization of one sample specimen. Four views of the articular surface are shown from a specimen that underwent Chamay extensor tendonereflecting exposure. The blue mesh represents the dyed visible surface. The black mesh represents the undyed and unexposed articular surface.

approaches are often used for fractures of the proximal phalanx, both extensor tendonesplitting and Chamay techniques are also often used in the setting of PIP joint arthroplasty.1e7 Swanson1 described a dorsal extensor tendone splitting approach in 1972 for PIP joint arthroplasty. In the current study, we sought to examine how much articular surface could be exposed through a tendon split only, to expose the maximum articular surface without detaching the central slip. In addition, assessment of the amount of exposure of the small articular J Hand Surg Am.

surface of the base of the middle phalanx was not a goal of the current study, but it could be addressed in future studies. In 1988, Chamay2 proposed a surgical exposure involving a distally based triangular tendinous flap through the extensor mechanism that is reattached at the end of the procedure. Chamay demonstrated this technique on a PIP joint arthroplasty, a tumor excision involving the ulnar condyle of the proximal phalanx, and an intra-articular unicondylar fracture of the proximal phalanx. Chamay immobilized the joint r

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FIGURE 5: Representative specimens from each dorsal surgical approach. Coronal end-on and volar aspects of the proximal phalangeal head are shown.

for 3 to 4 days and cautioned that extension could be limited and tenolysis might be necessary. Proponents of other approaches have criticized the Chamay approach for its tendency to form extensor tendon adhesions and scarring, impaired PIP joint mobility, and possible attenuation leading to extensor lag.3,8 The dorsal extensoresparing technique used in this study incised the transverse retinacular ligament on both sides, allowing the central slip and lateral bands to be elevated together. Although only 16% of the articular surface was visualized with this approach, it preserved the anatomy of the central slip insertion and left the extensor tendon intact. Lee and Teoh9 used this approach for 12 fingers with dorsal fracture-dislocations of the PIP joint, with good to excellent results. They started active flexion on the second postoperative day and light passive stretching exercises after 2 weeks.

reoperation owing to loss of motion, in part attributable to poor flexor tendon excursion. The volar approach to the PIP joint for PIP joint arthroplasty was advocated by Schneider.15 He cited its simplicity and facility for starting motion immediately. Some authors have adopted the volar approach as their standard approach for PIP joint arthroplasty because it spares the extensor mechanism and requires simpler postoperative therapy.8 However, this approach has been complicated by flexion contractures from flexor tendon scarring, bowstringing from incision of tendon pulleys, and swan neck deformities.5 Several authors prefer a lateral midaxial approach for fractures of the proximal phalanx because they found that the dorsal extensor tendonesplitting approach produced more scarring and increased the likelihood of tendon adherence.12,16 Those authors noted that excellent exposure of the fracture site was attainable through a midaxial incision, and excision of the lateral bands allowed for visualization of more proximal fractures. The lateral approach for PIP joint arthroplasty, as described by Lipscomb17 in 1967, requires detachment of the collateral ligaments and incision of the volar plate to just beyond the midline of the finger. Although it is used much less frequently than dorsal or volar approaches for PIP joint arthroplasty,

Alternative approaches to the PIP joint Volar and lateral surgical approaches to the PIP joint have been described for proximal phalangeal fracture fixation and PIP joint arthroplasty.3,7,8,10e14 Cheah and colleagues14 successfully treated unstable dorsal PIP joint fracture-dislocations through a volar approach. However, they cautioned that this approach can lead to J Hand Surg Am.

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REFERENCES

some authors think that the lateral approach leads to better range of motion and more rapid recovery.11 Because of the detachment of the collateral ligaments, volar plate, and dorsal capsule, the lateral approach has been criticized for its more extensive soft tissue disruption for both PIP joint arthroplasty and fracture treatment.10,18

1. Swanson AB. Flexible implant resection arthroplasty. Hand. 1972;4(2):119e134. 2. Chamay A. A distally based dorsal and triangular tendinous flap for direct access to the proximal interphalangeal joint. Ann Chir Main. 1988;7(2):179e183. 3. Afifi AM, Richards A, Medoro A, Mercer D, Moneim M. The extensor tendon splitting approach to the proximal interphalangeal joint: do we need to reinsert the central slip? J Hand Surg Br. 2010;35(3):188e191. 4. Bickel K. The dorsal approach to silicone implant arthroplasty of the proximal interphalangeal joint. J Hand Surg Am. 2007;32(6):8e11. 5. Bravo C, Rizzo M. Pyrolytic carbon proximal interphalangeal joint arthroplasty: results with minimum two-year follow-up evaluation. J Hand Surg Am. 2007;32(1):1e11. 6. Fahmy NR, Lavender A, Brew C. A conservative approach for proximal interphalangeal joint arthroplasty. J Hand Surg Br. 2001;26(3):235e237. 7. Linscheid RL, Murray PM, Vidal MA, Beckenbaugh RD. Development of a surface replacement arthroplasty for proximal interphalangeal joints. J Hand Surg Am. 1997;22(2):286e298. 8. Duncan SFM, Merritt MV, Kakinoki R. The volar approach to proximal interphalangeal joint arthroplasty. Tech Hand Up Extrem Surg. 2009;13(1):47e53. 9. Lee JYL, Teoh LC. Dorsal fracture dislocations of the proximal interphalangeal joint treated by open reduction and interfragmentary screw fixation: indications, approaches and results. J Hand Surg Br. 2006;31(2):138e146. 10. Stoecklein HH, Garg R, Wolfe SW. Surface replacement arthroplasty of the proximal interphalangeal joint using a volar approach: case series. J Hand Surg Am. 2011;36(6):1015e1021. 11. Segalman KA. Lateral approach to proximal interphalangeal joint implant arthroplasty. J Hand Surg Am. 2007;32(6):905e908. 12. Posner MA. Injuries to the hand and wrist in athletes. Orthop Clin North Am. 1977;8(3):593e618. 13. Pratt D. Exposing fractures of the proximal phalanx of the finger longitudinally through the dorsal extensor apparatus. Clin Orthop. 1959;15:22e26. 14. Cheah AEJ, Tan DMK, Chong AKS, Chew WYC. Volar plating for unstable proximal interphalangeal joint dorsal fracture-dislocations. J Hand Surg Am. 2012;37(1):28e33. 15. Schneider LH. Proximal interphalangeal joint arthroplasty: the volar approach. Semin Arthroplasty. 1991;2(2):139e147. 16. Field L, Freeland A, Jabaley M. Midaxial approach to the proximal phalanx for fracture fixation. Contemp Orthop. 1992;25:133e137. 17. Lipscomb PR. Synovectomy of the distal two joints of the thumb and fingers in rheumatoid arthritis. J Bone Joint Surg Am. 1967;49(6): 1135e1140. 18. Weiss A-PC, Hastings H. Distal unicondylar fractures of the proximal phalanx. J Hand Surg Am. 1993;18(4):594e599.

Clinical application of results Our findings have several implications for treatment of intra-articular proximal phalangeal fractures. Visualization of the articular surfaces of the PIP joint is often gained at the expense of incising or transecting obstructing structures, and the amount of articular surface visualized must be weighed against the amount of extensor mechanism violated. For fractures with proximal extension into the shaft, elevation of the extensor mechanism off the dorsum of the proximal phalanx may be required. Unlike the extensor tendonesplitting or Chamay approaches, access to the shaft of the proximal phalanx using the extensor tendonesparing approach can be easily achieved without disruption of the extensor mechanism. Only Weiss-Hasting Class 4 fractures that have a coronal plane unicondylar fracture that exits along the volar aspect of the articular surface may be difficult to anatomically reduce through the extensor tendonesparing approach.18 However, even the technique of Chamay,2 which exposes the most surface of all 3 dorsal surgical approaches, does not expose the anterior 50% of the proximal phalangeal head. Thus, if exposure of the anterior articular surface of the proximal phalanx is required, either the collateral ligaments must be incised or an alternative approach should be used. An understanding of the limitations inherent in each of the dorsal exposures of the PIP joint may help guide the appropriate surgical approach for the individual patient.

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Dorsal surgical approaches to the proximal interphalangeal joint: a comparative anatomic study.

Adequate exposure of the articular surface of the head of the proximal phalanx is essential for reduction of intra-articular fractures of the proximal...
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