623 (Figure 1 4-7 Anatomy radial and ulnar sagittalcrosses bands as it the(MP) joint. The metacarpophalangeal sagittalfrom bands the arise EDCtravel tendon dorsally transversely and to insert on the and Table 1). The threecontribute muscles that to thenism of extensor the mecha- digitorum are communis thelumbrical, extensor (EDC), and theseous. the The dorsal EDC is interos- stabilized by the An understanding ofand the mechanics anatomy mechanism of the of finger ismanagement crucial the to ofswan extensor boutonnière neck deformities and a hyperextension injuryjoint. Patients of present to hand theclinics surgery with a PIP broad spectrum ofchronic, acute, supple, and fixed boutonnière andswanneckdeformitiesthat requirearangeoftreatment. described 3 described a swan 2 in 1923, and is discussed in 1 osttraumatic boutonnièreswan neck and deformities are com- A consists of posttraumatic boutonnière and swan neck deformities. Abstract Boutonnière and swan neck deformities of theof finger trauma. can be The the complex result anatomyfinger of makes the understanding extensor the mechanismdeformities pathomechanics of challenging. of the These these posttraumatic deformitiesbe should confused not with thosebecause associated the with treatment inflammatory options areclinical often assessment very is different. essential Antreatment for accurate method. selecting Physical the examination, appropriate intrinsic-plus including tests, Elson and and plaindiagnosis. radiography A are variety important of tools nonsurgicalcan and for surgical be treatment used modalities tointerphalangeal restore joints the and motion rebalance ofAn the the understanding forces proximal of across and the these distal options, anatomy, joints. and clinical expected presentation, outcomes treatment is crucial for optimal treatment of Review Article aswanneckdeformitycausedby neck deformitya that chronic resulted disruptiontendon of from insertion the at the terminal distal(ie, phalanx ). Portis plex clinical problems that arepoorly often understood. Adeformity consists boutonnière of flexionproximal interphalangeal of (PIP) the joint and hyperextensioninterphalangeal of (DIP) theanatomy distal joint. andthis pathophysiology The deformity of Hauck was described by detail here. hyperextension of theflexion of PIP the DIP joint. joint Although swan and neck deformity was firstthe described setting in of inflammatoryposttraumatic arthritis, swan neckhas been deformity recognized fortury. nearly Watson-Jones a cen- P Posttraumatic Boutonnière and Swan Neck Deformities ’ 2015;23: the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. ª Copyright Academy of Orthopaedic Surgeons. subject of this article. J Am Acad Orthop Surg 623-632 http://dx.doi.org/10.5435/ JAAOS-D-14-00272 Copyright 2015 by the American Orthopaedic Surgeons and the American Society for SurgeryHand. of Neither the Dr. McKeonimmediate nor family any member has received anything of value from orstock has or stock optionsa held commercial in company orrelated institution directly or indirectly to the member is a memberbureau of or a has speakers madepresentations paid on behalf of,a serves paid as consultant to, and hasresearch received or institutional supportBiomet; from and serves asmember, a owner, board officer, ormember committee of the American Academy of From the Andrews Sportsand Medicine Orthopaedic Center, Birmingham, AL (Dr. McKeon) andOrthopedic the Institute, Vanderbilt Nashville, TN (Dr. Lee). Dr. Lee or an immediate family October 2015, Vol 23, No 10 Kathleen E. McKeon, MD Donald H. Lee, MD

Downloaded from https://journals.lww.com/jaaos by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3svV2EAJi1904VYKalCY5HmVgiBE4jGZlcbhU4LiAArY= on 11/22/2019 Downloaded from https://journals.lww.com/jaaos by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3svV2EAJi1904VYKalCY5HmVgiBE4jGZlcbhU4LiAArY= on 11/22/2019 Posttraumatic Boutonnière and Swan Neck Deformities

Figure 1

Illustrations of the radial (A) and dorsal (B) views of the finger demonstrating the anatomy of the extensor mechanism. A = common extensor tendon, B = sagittal band, C = transverse fibers, D = oblique fibers, E = conjoint lateral band, F = terminal tendon, G = flexor digitorum profundus tendon, H = dorsal interosseous muscle belly, I = lumbrical muscle belly, J = flexor digitorum superficialis tendon, K = medial tendon of the superficial head of the interosseous muscle, L = lateral tendon of the deep head of the interosseous muscle, M = flexor pulley, N = oblique retinacular ligament, O = transverse retinacular ligament, P = medial band of oblique fibers, Q = central slip, R = lateral slips, S = triangular ligament volar plate of the MP joint and the oblique fibers overlying the distal medial tendon abducts the digit. The volar periosteum of the proximal aspect of the P1. The oblique fibers deep head gives rise to the lateral phalanx (P1). In addition to stabi- join the medial bands of the inter- tendon, which passes superficial to lizing the EDC tendon, the sagittal osseous and, with the central slip, the sagittal band. Distally, the lateral bands help to extend the MP joint extend the PIP joint. The lumbrical tendon gives off contributions to the through a lasso effect. tendon terminates in the conjoint transverse fibers over the middle After crossing the MP joint, the lateral band. aspect of P1, which flex the MP joint. EDC tendon trifurcates into a central The dorsal interosseous contribu- Distal to the transverse fibers, the slip and two lateral slips. The central tion to the extensor mechanism is lateral tendon gives off contributions slip inserts onto the dorsal base of the arguably the most complex of the to the oblique fibers and the medial middle phalanx (P2) and extends the three muscles that contribute to the band of the interosseous, which PIP joint. The two lateral slips travel extensor mechanism.4-7 The anat- extend the PIP joint. The lateral radially and ulnarly to join their omy of first dorsal interosseous tendon then joins with the lateral slip respective conjoint lateral bands. muscle varies slightly from that of of the EDC and the lumbrical tendon The lumbrical muscle originates on other interosseous muscles1 but, in to form the conjoint lateral band. the flexor digitorum profundus ten- general, the dorsal interosseous Distal to the PIP joint, the radial don and is located on the radial aspect muscles are divided into two muscle and ulnar conjoint lateral bands are of the finger only. The lumbrical bellies, the superficial and the deep anchored dorsally by the triangular tendon passes volar to the deep in- heads.8 The superficial head gives ligament and volarly by the termetacarpal ligament at the level of rises to the medial tendon, which transverse retinacular ligament, the MP joint. Distally, the lumbrical passes deep to the sagittal band and preventing volar and dorsal sub- tendon gives off contributions to the inserts on the base of the P1. The luxation of the conjoint lateral

624 Journal of the American Academy of Orthopaedic Surgeons

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Kathleen E. McKeon, MD, and Donald H. Lee, MD

Table 1 Extensor Mechanism Anatomy Structure Origin Insertion Action

Common extensor tendon EDC muscle belly Central slip and lateral slip MP extension, PIP extension Sagittal band EDC tendon Volar plate of MP joint MP extension, stabilizes EDC tendon Transverse fibers Lateral tendon of deep head of EDC tendon MP flexion interosseous Oblique fibers Lateral tendon of deep head of Medial band of oblique PIP extension interosseous and lumbrical fibers tendon Conjoint lateral band Confluence of lateral tendon of Terminal tendon DIP extension deep head of the interosseous, lumbrical tendon, lateral slips Terminal tendon Conjoint lateral bands Distal phalanx DIP extension FDP tendon FDP muscle belly Distal phalanx DIP flexion Dorsal interosseous muscle Metacarpal Medial and lateral tendons MP flexion and abduction belly Lumbrical muscle belly FDP tendon Oblique fibers, radial lateral PIP and DIP extension band FDS tendon FDS muscle belly Middle phalanx PIP flexion Medial tendon of superficial Superficial head of Lateral tubercle of base of MP abduction head of interosseous interosseous proximal phalanx Lateral tendon of deep head of Deep head of interosseous Transverse fibers MP flexion interosseous Flexor pulley Volar metacarpal, phalanges, Volar metacarpal, Prevents bowstringing, allows volar plates phalanges, volar plates smooth gliding Oblique retinacular ligament Flexor sheath Terminal tendon Links PIP and DIP motion Transverse retinacular Flexor sheath Conjoint lateral bands Prevents dorsal subluxation of ligament conjoint lateral bands Medial band of oblique fibers Oblique fibers Dorsolateral tubercle of PIP extension middle phalanx Central slip EDC tendon Dorsal base of middle PIP extension phalanx Lateral slips EDC tendon Conjoint lateral bands DIP extension Triangular ligament Central slip (proximally), Terminal tendon (at apex) Prevents volar subluxation of conjoint lateral bands lateral bands (laterally)

DIP = distal interphalangeal, EDC = extensor digitorum communis, FDP = flexor digitorum profundus, FDS = flexor digitorum superficialis, MP = metacarpophalangeal, PIP = proximal interphalangeal

bands, respectively. Overlying the to the flexor sheath proximally and distal aspect of the P2, the radial and the terminal tendon distally.4-7 It Boutonnière Deformity ulnar conjoint lateral bands come passes dorsal to the axis of the DIP together to form the terminal ten- joint and volar to the axis of the PIP Pathomechanics don. The terminal tendon inserts joint, linking the action of the DIP As mentioned earlier, a boutonnière into the base of the distal phalanx and PIP joints. As the PIP joint deformity is a flexion deformity at and extends the DIP joint. extends, the oblique retinacular the PIP joint and a hyperextension The oblique retinacular ligament ligament tightens and transmits deformity at the DIP joint (Figure 2). is a controversial structure, but force across the terminal tendon, It is the result of a disruption of the most studies report that it attaches resulting in DIP extension. central slip and triangular ligament

October 2015, Vol 23, No 10 625

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Posttraumatic Boutonnière and Swan Neck Deformities

Figure 2 Figure 3 lateral bands as they are held distally by their attachments to the central slip. The patient is unable to generate any extension power at the DIP joint. With a boutonnière injury, flexion of the PIP joint does not advance the lateral bands distally secondary to disruption of the central slip. Ten- sion is generated in the terminal tendon because of the disrupted Photograph of the central slip. Therefore, the patient is demonstrating a boutonnière able to generate an abnormal deformity of the long finger. amount of active extension at the DIP joint with the PIP joint held in flexion (Figure 3). It may be neces- on the dorsum of the finger. Com- sary to perform a digital block before mon mechanisms of injury include the Elson test is done to allow an blunt trauma, an open laceration, or Photograph of the hand accurate assessment. a volar dislocation of the PIP demonstrating the Elson test. The Another useful clinical maneuver is joint.9,10 clinician holds the proximal the Boyes test, which is used to assess An injury to the central slip and interphalangeal joint in 90° of flexion ’ as the patient tries to extend the the patient s ability to actively flex triangular ligament allows the con- distal interphalangeal joint. the DIP joint with the PIP joint held joint lateral bands to subluxate in extension. Patients with an intact volarly with PIP flexion. Over time, extensor mechanism should be able a PIP joint extension lag develops. extensor mechanism. Although they to fully and actively flex the DIP Without prompt treatment, the PIP both have a similar clinical pre- joint. Patients with contracted lateral extension lag becomes a fixed flexion sentation, distinguishing between bands will have decreased active deformity, causing the lateral bands these two entities by using clinical flexion at the DIP joint when the PIP to become permanently subluxated examination tests, including the El- joint is held in extension. This test volarly. The injury to the central slip son and Boyes tests, is important may not be positive in an acute and triangular ligament also allows because the appropriate treatment setting.17 the lateral bands to migrate proxi- options are different for a pseudo Plain radiographs of the finger mally because of the loss of the teth- deformity. Treatment of a pseudo should be obtained in patients with ering effect of the central slip. As the deformity involves early, aggressive an injury to the PIP joint. Radiogra- lateral bands subluxate volarly, they motion, whereas treatment of a true phy may demonstrate subtle DIP migrate further proximally second- boutonnière deformity involves hyperextension that can be difficult ary to the pull of the lumbrical and a period of immobilization. to detect with a clinical examination interosseous muscles. This leads to alone. Central slip avulsions may increased tension on the terminal involve a bony fragment, which can Clinical Evaluation and tendon and hyperextension at the alter treatment. In general, advanced DIP joint. Classification imaging modalities are not needed for A true boutonnière deformity Several signs can lead the examiner to diagnosis of boutonnière deformity. should not be confused with suspect an injury to the extensor Chronic boutonnière deformities a pseudo deformity, in which mechanism in a patient with an injury are categorized using the Burton a hyperextension injury to the PIP to the PIP joint. The Elson test is the classification (Table 2).18 This clas- joint leads to a PIP flexion contrac- most reliable maneuver for diagnosis sification system is based on clinical ture.11-14 In a pseudo deformity, the of an acute boutonnière injury.15,16 examination findings and the radi- central slip and triangular ligament The examiner holds the PIP joint in ographic appearance of the PIP joint. remain competent, and the DIP joint 90° of flexion and instructs the retains full mobility. The flexion patient to actively extend the DIP is caused by scarring of joint. With an intact extensor Nonsurgical Management the volar plate and joint capsule mechanism, holding the PIP joint in For patients who present with an rather than by a derangement of the 90° of flexion causes slack in the acute, closed boutonnière injury

626 Journal of the American Academy of Orthopaedic Surgeons

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Kathleen E. McKeon, MD, and Donald H. Lee, MD

(Burton stage I), nonsurgical man- Table 2 agement is generally recommended; Burton Classification of Boutonnière Deformity18 this consists of splinting the PIP joint in extension for 4 to 8 weeks to allow Stage Description the central slip to heal. Active DIP I Supple, passively correctable deformity flexion exercises are performed II Fixed contracture, contracted lateral bands, no joint involvement multiple times daily to pull the lateral III Volar plate and collateral ligament , intra-articular bands dorsally and to counteract the fibrosis proximal migration of the lateral IV Volar plate and collateral ligament contractures, intra-articular bands. After 4 to 8 weeks of full-time fibrosis plus proximal interphalangeal joint arthritis splinting, PIP flexion exercises are introduced, but the PIP extension splint is worn at night for an addi- tional 4 to 6 weeks.10 Table 3 Chronic, fixed boutonnière de- ’ 18 formities (Burton stage II) are often Burton s Principles for Treatment of Chronic Boutonnière Deformity amenable to nonsurgical manage- Surgical treatment of boutonnière deformities should be done only by ment, as long as full passive PIP experienced hand surgeons. extension can be achieved with Surgical treatment is rarely necessary for supple boutonnière deformities. a therapy protocol. Full passive PIP Preoperative and postoperative therapy programs are an essential part of extension is achieved with serial surgical treatment. casting or dynamic splinting over Tendon procedures should be done after full passive PIP joint extension has been achieved. Procedures may need to be staged, with tendon rebalancing a period of 6 to 12 weeks. Active DIP following a PIP contracture release. flexion exercises are a critical part of If arthritic change is present, tendon rebalancing should be combined with the therapy protocol in this situation, implant arthroplasty or arthrodesis. as well. Once full passive PIP Flexor function should not be jeopardized in an attempt to achieve full extension. extension is achieved, it is main- All procedures involve rebalancing the extensor mechanism to divert force from tained with extension splinting for 6 the DIP joint to the PIP joint. to 12 weeks, followed by a protocol to gradually resume PIP flexion. DIP = distal interphalangeal, PIP = proximal interphalangeal

Surgical Management débridement, a primary repair of the nonsurgically is best left to an Acute Boutonnière Deformity central slip can be performed or the experienced hand surgeon. Surgical intervention is occasionally slip can be reattached to the base of necessary for boutonnière defor- the P2 with a bone anchor or Chronic Boutonnière Deformity mities. In patients with acute, closed through bone tunnels. After repair of Surgical management of chronic injuries (Burton stage I) that are not the central slip, the PIP joint is pin- boutonnière deformities should be amenable to full-time PIP extension ned in extension for 6 weeks to approached with caution. Seven splinting, pinning of the PIP joint protect the repair. principles for management of may be beneficial. The PIP joint is Bony avulsions of the central slip a chronic boutonnière deformity extended, effectively reducing the may also warrant surgical manage- described by Burton18 are outlined in lateral bands, and a 0.045-inch ment in the acute setting. Although Table 3. Patients with a boutonnière Kirschner wire is placed across the patients with small bony fragments deformity generally retain full flexion joint. The wire is left in place for 4 to may be managed nonsurgically as and grip strength and have few 6 weeks and then removed, followed described earlier, larger bony frag- functional limitations. Surgical inter- by initiation of PIP flexion ments require fixation to the base of vention may lead to extension con- exercises.10 the P2 with Kirschner wires or tractures of the PIP joint and poor Patients with acute, open bouton- screws. Other factors, such as chro- functional outcomes. Prior to under- nière injuries often have joint nicity, displacement, and patient taking any surgical reconstruction, it involvement and may benefit from compliance, should also be consid- is imperative to thoroughly discuss irrigation and débridement in the ered. The decision to treat a bony the risks and expected outcomes with operating room. At the time of boutonnière injury surgically or the patient.

October 2015, Vol 23, No 10 627

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Posttraumatic Boutonnière and Swan Neck Deformities

Table 4 Figure 4 Etiology of Posttraumatic Boutonnière and Swan Neck Deformities Deformity Etiology

Boutonnière Disruption of central slip and triangular ligament Swan neck Extrinsic Disruption of terminal tendon (mallet) Wrist or MP joint flexion contracture Intrinsic Chronic MP volar subluxation Ischemic contracture Tendon adhesion Articular Photograph of the ring finger Volar plate/capsule injury demonstrating a swan neck (hyperextension) deformity in the setting of a chronic Disruption of FDS mallet deformity.

FDS = flexor digitorum superficialis, MP = metacarpophalangeal central slip is attenuated and a reconstructive procedure, such as a turndown procedure, is required. If a patient wishes to proceed with and sutured together in the midline, Finally, for patients with arthritic surgical correction of a chronic distal to the PIP joint. This effectively change and pain at the PIP joint boutonnière deformity, the first step diverts all active extension power associated with a long-standing is to achieve full passive PIP joint (extrinsic and intrinsic) to the PIP boutonnière deformity, an arthrod- extension with a preoperative ther- joint, while maintaining DIP exten- esis is the procedure of choice. apy program that includes splinting sion through the action of the pre- or casting, a dynamic external fix- served oblique retinacular ligament. ator, or an open joint contracture Curtis et al22 described a staged Swan Neck Deformity release. Once full passive PIP joint reconstruction performed with local extension has been achieved, several anesthesia to allow accurate assess- Etiology tendon rebalancing procedures can ment of active motion intra- Unlike a boutonnière deformity, be used. operatively. In the first stage, an which is the result of an injury to the The simplest tendon rebalancing extensor tenolysis is performed central slip and triangular ligament, procedure is a terminal tendon te- through a dorsal incision. If full a posttraumatic swan neck deformity notomy (ie, distal Fowler or Dolphin active extension is present at this can result from a variety of initial in- tenotomy).19,20 By dividing the ter- point, the procedure is complete. If juries.24-26 Zancolli26 classified these minal tendon, the hyperextension an extensor lag remains, then the injuries into three categories: extrinsic, force on the DIP joint is removed. transverse retinacular ligaments are intrinsic, and articular (Table 4). The extensor mechanism retracts, transected, allowing the lateral Extrinsic causes of swan neck de- allowing for more force to be bands to swing dorsally. Active formities are the result of excessive transmitted to the PIP joint and extension is reassessed. If full active extension force on the P2. In the set- decreasing the PIP extensor lag. extension is present, then the pro- ting of a flexible PIP joint, hyperex- Postoperatively, a DIP extension cedure is complete. If an extensor lag tension develops over time, with splint is worn at all times for 6 to 8 ,20° remains, then a Fowler tenot- chronic extension force. For exam- weeks, except during range-of- omy is performed. If an extensor lag ple, disruption of the terminal tendon motion (ROM) exercises. .20° remains after the transverse (eg, a mallet finger injury) allows the The tendon rebalancing technique retinacular ligaments are transected, lateral bands to migrate proximally, developed by Littler and Eaton21 can then the central tendon is dissected increasing the extension force on the also be used. Through a dorsal free and advanced 4 to 6 mm into P2 (Figure 4). Posttraumatic wrist or incision, the lateral bands are a drill hole at the base of the P2.23 MP joint flexion contractures also sharply released from the lumbrical The slackened lateral bands can then increase the tension on the EDC muscle contribution and the oblique be loosely sutured dorsally to the tendon, increasing the extensor force retinacular ligament. The lateral central tendon to augment the ten- on the P2 and leading to deformity bands are then mobilized dorsally don advancement. Occasionally, the over time.

628 Journal of the American Academy of Orthopaedic Surgeons

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Kathleen E. McKeon, MD, and Donald H. Lee, MD

The intrinsic causes of swan neck Table 5 deformities are related to tightness of Classification System for Swan Neck Deformity the intrinsic muscles, or an intrinsic- plus finger. Chronic volar sub- Type Characteristics luxation of the MP joint (either I Full range of motion, no intrinsic tightness, no functional limitations posttraumatic or the result of II Intrinsic tightness inflammatory arthritis) can lead to III Stiff PIP in all positions of the MP joint, joint space preserved tightening of the intrinsic muscles IV Severe arthritic change over time. Other mechanisms include ischemic contractures that develop MP = metacarpophalangeal, PIP = proximal interphalangeal after compartment syndrome of the hand and intrinsic tendon adhesions. Articular causes of swan neck deformity include injury to or recommendations for a posttraumatic fragment is large enough to undergo degeneration of the volar structures swan neck deformity are significantly open reduction and internal fixation. of the PIP joint. This can be the result different than those for a swan neck The presence of arthritis will change of a posttraumatic injury, inflamma- deformity associated with autoim- the treatment recommendations, as tory arthritis, or generalized hyper- mune synovitis. If signs of inflamma- well. Advanced imaging (eg, MRI, laxity. Hyperextension injury to the tory arthritis are present, a referral to CT) is rarely indicated. PIP joint can lead to disruption of the a rheumatologist is indicated. The The classification of swan neck de- volar plate and volar capsule, which flexibility of the DIP, PIP, and MP formities is based on the ROM of the can lead to chronic insufficiency of joints should be assessed with active PIP joint and radiographic findings. the volar structures if not appropri- and passive motion. The integrity of This classification system can serve as ately treated. The flexor digitorum the FDS tendon should be assessed, as the basis for treatment recom- 10 superficialis (FDS) tendon also serves well. mendations (Tables 5 and 6). as a palmar stabilizer of the PIP joint; The Bunnell test can be used to therefore FDS disruptions can also assess the flexibility and tightness of Nonsurgical Management the intrinsic muscles.27 Because the lead to PIP hyperextension deformity For patients with mild swan neck intrinsic tendons pass volar to the over time. deformities and full active flexion of MP joint axis of rotation, they are the PIP joint, nonsurgical manage- relaxed and tensioned with MP joint ment is often indicated. These pa- Clinical Evaluation and flexion and extension, respectively. tients often report difficulty initiating Classification Conversely, because the intrinsic flexion from the hyperextended pos- tendons pass dorsal to the PIP joint A careful history and physical exam- ture. They may also report snapping axis of rotation, they are relaxed ination can help the clinician deter- of the lateral bands, which occurs with PIP joint extension and ten- mine the etiology of the swan neck when the dorsally subluxated lateral sioned with PIP joint flexion. If the deformity. A history of prior injuries bands reduce volarly as the finger intrinsic muscles are excessively (eg, mallet injury, FDS tendon lacer- moves from hyperextension to flex- tight, holding the MP joint in ation, PIP joint hyperextension ion. A silver ring splint or other extension will tighten the intrinsic injury) makes determining the etiol- functional splint that limits PIP tendons even further and increase the ogy straightforward. In the absence hyperextension while allowing full extension force across the PIP joint. of a known injury, physical exami- flexion can limit these symptoms. Therefore, a patient with intrinsic nation and imaging can aid in These splints are low profile, easy to muscle tightness will have a decrease diagnosis. Some persons with liga- wear, and aesthetically pleasing28 mentous laxity are able to hold their in passive and active flexion of the (Figure 5). fingers in a swan neck posture natu- PIP joint with the MP joint held in rally, but they rarely have any func- extension. tional limitations. Radiography is an important part of Surgical Management The physical examination should the clinical assessment of swan neck For patients with mild deformity who start by assessing the patient for signs deformity. The presence of fractures do not wish to wear a splint or those of inflammatory arthritis, such as the (eg, bony mallet, avulsion fracture of with more severe deformity, surgery involvement of multiple joints in the the PIP volar plate) may change the is indicated. The choice of procedure hands and wrists because the treatment treatment plan, particularly if the is based on the severity of the

October 2015, Vol 23, No 10 629

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Posttraumatic Boutonnière and Swan Neck Deformities

Table 6 Management Options for Swan Neck Deformity Type Metacarpophalangeal Joint Proximal Interphalangeal Joint Distal Interphalangeal Joint

I None Splint, a procedure to limit hyperextension, Nonsurgical management, including FDS tenodesis, oblique arthrodesis retinacular ligament reconstruction, lateral band translocation, dermadesis, volar plate repair (if the etiology is a volar plate injury) II Intrinsic release, reconstruction Procedure to limit hyperextension Nonsurgical management, as needed (see type I) arthrodesis III Intrinsic release, Stepwise approach beginning with PIP Nonsurgical management, reconstruction as needed joint manipulation and then a skin release arthrodesis or lateral band mobilization, if needed. At the conclusion of procedure, flexor tendon gliding is checked. Once full PIP motion present, a procedure to limit hyperextension (see type I) can be performed. IV Intrinsic release, Arthroplasty combined with procedure to Nonsurgical management, reconstruction as needed limit hyperextension (see type I), arthrodesis arthrodesis

FDS = flexor digitorum superficialis, PIP = proximal interphalangeal

the flexor sheath on either side of the sutured to the flexor tendon sheath, Figure 5 A3 pulley. One slip of FDS is incised with the PIP joint held in 30° of approximately 1.5 cm from its flexion. In theory, this reconstruc- insertion, leaving the distal attach- tion should correct the PIP hyper- ment intact. The PIP joint is flexed extension by providing a static tether 20° to 30°, and the detached FDS slip as well as increasing the extension is fixed proximally to the bone with force on the DIP joint to correct the an anchor, or it is sutured to the distal DIP flexion deformity. In practice, edge of the A2 pulley, forming a static however, the terminal tendon is tether to PIP hyperextension. Post- often attenuated and incompetent, so Photograph of a silver ring splint operatively, the joint is splinted in 30° the DIP joint deformity is rarely used for management of swan neck of flexion for 3 weeks. At 3 weeks, completely corrected with this deformity. active flexion is initiated, but exten- method. Alternatively, the oblique sion block splinting is continued to retinacular ligament can be re- deformity. For patients with type I prevent hyperextension for at least an constructed using an autologous deformities and full ROM of the PIP additional 3 weeks. tendon graft.33 joint, soft-tissue procedures are indi- Oblique retinacular ligament When a disruption of the volar cated to limit hyperextension of the reconstruction is another technique plate was the initial injury that led to PIP joint. These procedures can be used to address hyperextension of the the swan neck deformity, a direct 30-32 combined with an arthrodesis of the PIP joint. The ulnar lateral band repair of the volar plate is indi- DIP joint if the flexion contracture of is freed from the extensor mecha- cated.34-36 Volar plate repair can be the DIP joint is severe. nism and incised proximally, leaving done through a volar incision, using Several soft-tissue procedures have the distal insertion intact. The lateral bone anchors or drill holes in the been used to limit hyperextension of band is then transposed volar to the base of the P2. the PIP joint. The most widely used Cleland ligaments to bring it volar to Lateral band translocation and technique is the FDS tenodesis, or FDS the axis of rotation of the PIP joint. dermadesis have also been used to sling technique.29 Through a volar The lateral band is passed to the manage mild swan neck defor- zig-zag incision, a window is made in opposite side of the finger and mities.26,37 These procedures can be

630 Journal of the American Academy of Orthopaedic Surgeons

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Kathleen E. McKeon, MD, and Donald H. Lee, MD done alone or in conjunction with of the previously described proce- 2. Watson-Jones R: Fractures and Joint Injuries, ed 3. Baltimore, MD, Williams and one of the procedures described dures to address PIP hyperextension Wilkins Co, 1943, p 592. earlier. can be performed. Typically, an 3. Portis RB: Hyperextensibility of the For patients with a type II swan intrinsic release is necessary. proximal interphalangeal joint of the finger neck deformity with intrinsic tight- For patients with a type IV swan following trauma. J Bone Joint Surg Am ness, an intrinsic release should be neck deformity, the PIP joint should 1954;36(6):1141-1146. combined with one of the procedures be addressed with arthroplasty or 4. Smith RJ: Balance and kinetics of the fingers described earlier to address PIP arthrodesis. If arthroplasty is per- under normal and pathological conditions. Clin Orthop Relat Res 1974;104:92-111. hyperextension. An intrinsic release formed, it is necessary to address the is performed through a dorsoulnar soft-tissue balancing around the joint 5. Smith RJ: Intrinsic muscles of the fingers: Function, dysfunction, and surgical longitudinal incision over the P1. The with a procedure to limit PIP hyper- reconstruction. AAOS Instructional Course structures of the extensor mechanism extension. The decision between ar- Lectures Volume 26, Rosemont, IL, American Academy of Orthopaedic are identified. The lateral band and throplasty and arthrodesis depends Surgeons, 1975, pp 200-220. oblique fibers are incised at the level on many variables and should be 6. Landsmeer JM: The anatomy of the dorsal of the distal half of the P1, with care made on a case-by-case basis for each aponeurosis of the human finger and its taken to leave intact the central slip, patient. functional significance. Anat Rec 1949;104 the lateral slips of the extensor ten- (1):31-44. don, and the transverse fibers.38,39 7. Tubiana R, Valentin P: The physiology of Summary For patients with a type III swan the extension of the fingers. Surg Clin North Am 1964;44:909-918. neck deformity, full passive ROM of Determining the appropriate course the PIP joint must be restored before 8. Masquelet AC, Salama J, Outrequin G, of treatment for each patient with Serrault M, Chevrel JP: Morphology and addressing the deformity. This can be a posttraumatic boutonnière or swan functional anatomy of the first dorsal done with a stepwise approach, interosseous muscle of the hand. Surg neck deformity requires the clinician Radiol Anat 1986;8(1):19-28. starting with a closed gentle manip- to have a thorough understanding of 9. Souter WA: The problem of boutonniere ulation of the PIP joint, with the goal the anatomy of the extensor mech- of achieving 80° to 90° of flexion. If deformity. Clin Orthop Relat Res 1974; anism, the etiology of the deformity, 104:116-133. motion is restored, but the dorsal the available nonsurgical manage- skin is blanched and at risk of 10. Strauch RJ: Extensor tendon injury, in ment modalities, and the techniques Wolfe SW, Hotchkiss RN, Pederson WC, ’ necrosis, a skin release can be done. for surgical correction. The clinician Kozin SH, eds: Green s Operative Hand The skin release is performed distal Surgery, ed 6. Philadelphia, PA, Elsevier, should work with the patient to 2011, vol 1, pp 159-188. to the joint, with an oblique incision elucidate any functional limitations made over the P2. The skin is al- 11. McCue FC, Honner R, Gieck JH, and to ensure that he or she main- Andrews J, Hakala M: A pseudo- lowed to heal by secondary inten- tains realistic expectations. . Hand 1975;7(2): tion. If a closed manipulation does 166-170. not restore adequate motion, an 12. Rothwell AG: The pseudo-boutonniere open release of the lateral bands is References deformity. NZMedJ1979;89(628):51-54. performed by making two parallel 13. McCue FC, Honner R, Johnson MC, incisions on either side of the central Evidence-based Medicine: Levels of Gieck JH: Athletic injuries of the proximal evidence are described in the table of interphalangeal joint requiring surgical slip, allowing the lateral bands to treatment. J Bone Joint Surg Am 1970;52 move volarly.24 contents. In this article, reference 28 (5):937-956. is a level II study. References 11, 13, After passive PIP flexion is restored 14. Bowers WH: The proximal interphalangeal with any of these methods, flexor 14, 16, 19, 20, 22, 23, 29-33, and joint volar plate: II. A clinical study of tendon gliding should be assessed to 35-38 are level IV studies. References hyperextension injury. J Hand Surg Am 1981;6(1):77-81. ensure that no secondary adhesions 3, 8, 12, 16, 21, 27, 30, and 34 are of the flexor tendons are present. This level V expert opinion. 15. Rubin J, Bozentka DJ, Bora FW: Diagnosis of closed central slip injuries: A cadaveric can be done by assessing active References printed in bold type are analysis of non-invasive tests. J Hand Surg motion if the surgery is performed those published within the past 5 Br 1996;21(5):614-616. under local anesthesia or by making years. 16. Elson RA: Rupture of the central slip of the an incision in the palm and pulling extensor hood of the finger: A test for early 1. Hauck G: Die Ruptur der diagnosis. J Bone Joint Surg Br 1986;68(2): direct traction on the flexor tendons. Dorsalaponeurose am ersten 229-231. Once adequate PIP joint motion has Interphalangealgelenk, zugleich ein Beitrag zur Anatomic und Physiologie der 17. Boyes JH: Bunnell’s Surgery of the Hand, been achieved and smooth flexor Dorsalaponeurose. Arch Klin Chirurgie ed 5. Philadelphia, PA, Lippincott, 1970, tendon gliding has been ensured, any 1923;123:197-232. p 393.

October 2015, Vol 23, No 10 631

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited. Posttraumatic Boutonnière and Swan Neck Deformities

18. Burton RI: Extensor tendons-late 25. Dreyfus JN, Schnitzer TJ: Pathogenesis and chronic mallet finger deformity. J Hand reconstruction, in Green DP, ed: differential diagnosis of the swan-neck Surg Am 1984;9(3):399-404. Operative Hand Surgery. New York, NY, deformity. Semin Arthritis Rheum 1983;13 ChurchillLivingstone,1988,pp (2):200-211. 33. Thompson JS, Littler JW, Upton J: The 2073-2116. spiral oblique retinacular ligament (SORL). 26. Zancolli E: Structural and Dynamic Bases J Hand Surg Am 1978;3(5):482-487. 19. Meadows SE, Schneider LH, Sherwyn JH: of Hand Surgery, ed 2. Philadelphia, PA, Treatment of the chronic boutonniere Lippincott, 1979, pp 64-79, 92-103. 34. Onishi Y, Fujioka H, Doita M: Treatment deformity by extensor tenotomy. Hand Clin of chronic post-traumatic hyperextension 1995;11(3):441-447. 27. Bunnell S: Ischaemic contracture, local, in deformity of proximal interphalangeal joint the hand. J Bone Joint Surg Am 1953;35(1): using the suture anchor: A case report. 20. Stern PJ: Extensor tenotomy: A technique 88-101. Hand Surg 2007;12(1):47-49. for correction of posttraumatic distal interphalangeal joint hyperextension 28. van der Giesen FJ, Nelissen RG, van 35. Wollstein R, Watson HK, Carlson L: A deformity. J Hand Surg Am 1989;14(3): Lankveld WJ, et al: Swan neck deformities technique for the repair of chronic volar 546-549. in : A qualitative study plate avulsion of the proximal on the patients’ perspectives on hand interphalangeal joint: A review of 54 cases. 21. Littler JW, Eaton RG: Redistribution of function problems and finger splints. Plast Reconstr Surg 2006;117(4): forces in the correction of Boutonniere Musculoskeletal Care 2010;8(4):179-188. 1239-1245. deformity. J Bone Joint Surg Am 1967;49 (7):1267-1274. 29. Catalano LW III, Skarparis AC, Glickel SZ, 36. Melone CP Jr, Polatsch DB, Beldner S, et al: Treatment of chronic, traumatic Khorsandi M: Volar plate repair for 22. Curtis RM, Reid RL, Provost JM: A staged hyperextension deformities of the proximal posttraumatic hyperextension deformity of technique for the repair of the traumatic interphalangeal joint with flexor digitorum the proximal interphalangeal joint. Am J boutonniere deformity. J Hand Surg Am superficialis tenodesis. J Hand Surg Am Orthop (Belle Mead NJ) 2010;39(4): 1983;8(2):167-171. 2003;28(3):448-452. 190-194.

23. Caroli A, Zanasi S, Squarzina PB, 30. Ahmed HA, Goldie BS: Proximal 37. Tonkin MA, Hughes J, Smith KL: Lateral Guerra M, Pancaldi G: Operative treatment interphalangeal joint instability: A dynamic band translocation for swan-neck deformity. of the post-traumatic boutonnière technique for stabilization. J Hand Surg Br JHandSurgAm1992;17(2):260-267. deformity: A modification of the direct 2002;27(4):354-355. anatomical repair technique. J Hand Surg 38. Harris C Jr, Riordan DC: Intrinsic Br 1990;15(4):410-415. 31. Ko JH, Kalainov DM, Hsu LP, Fang RC, contracture in the hand and its surgical Mastey RD: Double lateral band transfer treatment. J Bone Joint Surg Am 1954;36 24. Feldon P, Terrono AL, Nalebuff EA, for treatment of traumatic hyperextension (1):10-20. Millender LH: Rheumatoid arthritis and instability of the proximal interphalangeal other connective tissue disease, in joint: A report of two cases. Hand (N Y) 39. Shin AY, Amadio PC: The stiff finger, in Wolfe SW, Hotchkiss RN, Pederson WC, 2012;7(1):108-113. Wolfe SW, Hotchkiss RN, Pederson WC, Kozin SH, eds: Green’s Operative Hand Kozin SH, eds: Green’s Operative Hand Surgery, ed 6. Philadelphia, PA, Elsevier, 32. Kleinman WB, Petersen DP: Oblique Surgery, ed 6. Philadelphia, PA, Elsevier, 2011, vol 2, pp 1993-2066. retinacular ligament reconstruction for 2011, vol 1, pp 355-387.

632 Journal of the American Academy of Orthopaedic Surgeons

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited.