33: Correction of Swan-Neck Deformity in the Rheumatoid Hand

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Procedure 33 Correction of Swan-Neck Deformity in the Rheumatoid Hand

Yoshitaka Minamikawa, Akio Minami

imageSee Video 25: Lateral Band Release for Rheumatoid Swan-Neck Deformity

Indications

image Treatment of swan-neck deformity is based on the flexibility of the proximal interphalangeal (PIP) joint and condition of the joint cartilage.

image The Nalebuff classification is the most widely accepted and useful method for surgical decision-making.

• Type 1: PIP joint is flexible in all positions of the metacarpophalangeal (MCP) joint.
• Type 2: PIP joint flexion is limited in certain positions of the MCP joint.
• Type 3: PIP joint flexion is limited irrespective of position of the MCP joint.
• Type 4: PIP joints are stiff and have a poor radiographic appearance.

image Type I deformities need a procedure to limit PIP hyperextension (e.g., splint, dermodesis, flexor digitorum superficialis [FDS] tenodesis) and restore distal interphalangeal (DIP) extension (e.g., tenodermodesis, fusion).

image Type II deformities require an intrinsic release and/or MCP joint arthroplasty in addition to the procedure for type I.

image Type III deformities require restoration of flexion of the PIP joint by manipulation, lateral band mobilization, and lengthening of the central slip depending on the severity of soft tissue contracture.

image Arthrodesis of the PIP joint is often recommended for type IV deformities with joint destruction; however, implant arthroplasty is always an option.

Examination/Imaging

Clinical Examination

image Active and passive range of motion of the PIP joint is tested with the MCP joint in extension and flexion. This is to evaluate whether the intrinsic muscles are contributing to the restricted PIP joint motion. Restriction in radial and ulnar deviation is also tested with the MCP joint in extension to evaluate which of the intrinsic muscles is responsible for the PIP joint tightness.

image When active motion of the PIP is not nearly equal to passive motion, adhesions of the flexor tendons must be suspected.

image When the PIP joint is flexible regardless of the metacarpophalangeal (MCP) joint position (type I), a PIP extension block splint may correct the deformity while restoring full flexion (Fig. 33-1A).

image When flexion of the PIP joint is restricted with the MCP joint in extension and radial deviation, ulnar intrinsic muscle tightness exists.

image When passive flexion of the PIP is limited with the MCP joint in flexion, the pathology is the stiff PIP joint (type III) (Fig. 33-1B).

image The typical swan-neck deformity is associated with flexion contracture of the MCP joint, hyperextension of the PIP joints, and dorsally displaced lateral bands (Fig. 33-2).

image

FIGURE 33-1

image

FIGURE 33-2

Imaging

image A radiograph of the hand is useful to assess the condition of the PIP joint and the MCP joint.

Surgical Anatomy

image A swan-neck deformity can occur as a result of abnormalities at the wrist, MCP joint, PIP joint, or DIP joint (Fig. 33-3).

image Synovitis within the PIP joint leads to stretching, weakening, and eventually destruction of the volar plate and collateral ligaments and the insertion of the FDS, resulting in the loss of palmar restraint at the PIP joint. This loss allows the normal extensor forces to cause abnormal hyperextension of the PIP joint.

image Synovitis of the MCP joint causes attenuation of the volar plate, resulting in volar subluxation of the MCP joint. Over time, volar subluxation results in shortening of the intrinsic muscles, leading to PIP joint hyperextension and ultimately swan-neck deformity.

image DIP joint synovitis can cause weakening and rupture of the terminal extensor tendon insertion, leading to the development of a mallet deformity. The proximal migration of the terminal extensor insertion causes the lateral bands to become lax. All the power of the common extrinsic extensor is now directed toward the central slip that inserts into the middle phalanx. Over time, the volar supporting structures of the PIP joint are weakened, and the PIP joint is forced into hyperextension, resulting in a swan-neck deformity.

image Synovitis at the wrist joint can lead to carpal collapse, carpal supination, and ulnar translation. Carpal collapse leads to a relative lengthening (relaxation) of the long flexor and extensor tendons. The interosseous muscle can then overpower the action of the extrinsic muscles and lead to MCP joint flexion and PIP joint extension, which over a prolonged period causes a physiologic shortening of the intrinsic muscles.

image

FIGURE 33-3

Procedures to Prevent Hyperextension of the PIP Joint (for Types 1 to 3)

Bone Anchor Repair of the Volar Plate

Step 1

image A zigzag incision is made over the long finger crease (Fig. 33-4A).

image

FIGURE 33-4

Step 1 Pitfalls

Care must be taken not to injure the digital nerve at the tip of the flap. The nerve is just beneath the skin (Fig. 33-4B). The other digital nerve is identified at the base of the flap and protected (Fig. 33-4C).

Step 2

image The accessory collateral ligament is identified and incised (Fig. 33-5A and B). The volar plate with the entire flexor sheath is retracted laterally to expose the head of the proximal phalanx (Fig. 33-5C).

image

FIGURE 33-5

Step 3

image A drill hole is made in the center of the palmar surface of the proximal phalanx about 5 to 7 mm proximal to the joint line (Fig. 33-6A).

image A bone anchor (Mitek Mini, Mitek Surgical Products Inc., Norwood, Mass) is placed in the hole (Fig. 33-6B).

image

FIGURE 33-6

Step 3 Pitfalls

It is important to visually confirm that the anchor has gone all the way into the drill hole before removing the instrument (Fig. 33-6C).

Step 4

image The bone anchor typically has two needles with sutures. One needle is passed from the dorsolateral aspect of the volar plate (Fig. 33-7A) to emerge at the central portion of the volar plate (Fig. 33-7B). It is then passed through the edge of the previously divided accessory collateral ligament (Fig. 33-7C).

image

FIGURE 33-7

Step 5

image The sutures are tied to each other, aiming to maintain the PIP joint in about 10 degrees of flexion (Fig. 33-8A).

image The other needle is passed in a similar fashion on the other side. After the second suture is tied, the PIP joint should be positioned in about 15 to 20 degrees of flexion. The first suture loop needs to shift medially to develop sufficient tension in the second suture loop (Fig. 33-8B and C).

image

FIGURE 33-8

FDS Tenodesis

Step 1

image One of the slips of the FDS is divided proximal to A2 pulley (Fig. 33-9A and B).

image

FIGURE 33-9

Step 2

image A hole is made in the distal third of the proximal phalanx from the volar to lateral surface. The FDS slip is passed through this hole from volar to lateral and is sutured with the PIP joint in slight flexion (Fig. 33-9C).

Step 2 Pearls

A single slip of FDS is usually too large to pass through the hole. It is better to use half of the slip instead. Another option would be to pass the entire slip through the A2 pulley.

Retinacular Ligament Reconstruction

Step 1

image The ulnar lateral band is divided at the midproximal phalanx (Fig. 33-10A).

image

FIGURE 33-10

Step 2

image The divided lateral band is dissected distally and passed below the Cleland ligament so that the ulnar lateral band is now volar to the axis to the PIP joint to maintain the PIP joint in flexion. The lateral band is sutured to the A2 pulley or into the bone of the proximal phalanx to maintain the PIP joint in 15 to 20 degrees of flexion (Fig. 33-10B and C).

Step 2 Pearls

An extension block pin must be used to protect the reconstructed retinacular ligament.

Procedures to Correct DIP Joint Deformity (for Types 1 to 4)

Dorsal Tenodermodesis of the DIP Joint

Step 1

image An ellipse of skin is excised from the dorsum of the DIP joint (Fig. 33-11A).

image

FIGURE 33-11

Step 2

image A 3-0 nylon horizontal mattress suture is passed such that it holds a good bite of both the skin and the underlying extensor tendon (Fig. 33-11B).

Step 3

image The DIP joint is held in extension, and the 3-0 nylon suture is tied (Fig. 33-11C).

Step 4

image An oblique K-wire is inserted to maintain the DIP joint in extension and is cut off beneath the skin (Fig. 33-11D).

Step 4 Pearls

Although soft tissue reconstruction for DIP joint extension is often discouraged and arthrodesis is recommended, tenodermodesis combined with pinning the DIP joint (>2 months) creates a stiff DIP joint that will also allow slight motion.

Procedures to Correct a Stiff Swan-Neck Deformity (Type 3)

Lateral Band Mobilization

Step 1

image The extensor apparatus is exposed by a dorsal curved incision. The lateral bands are dorsally displaced and adherent to the central slip. They do not move laterally or palmar, which causes the extension contracture (Fig. 33-12A).

image

FIGURE 33-12

Step 2

image The lateral bands are separated from the central slip from distal to proximal by sharp dissection (Fig. 33-12B).

Step 2 Pearls

Try to preserve a wide central slip. Occasionally, the demarcation between the central slip and the lateral bands is unclear. A wider central slip can better resist accidental rupture during joint manipulation and is easier to lengthen.

Step 3

image The PIP joint is gently flexed to enable the lateral band to move laterally and palmar (Fig. 33-12C).

Step 3 Pearls

The dorsal capsule and the dorsal portions of the collateral ligaments may need to be released to obtain good flexion at the PIP joint.

Step 3 Pitfalls

Tension of the central slip should be monitored carefully during manipulation to prevent rupture.

Step-Cut (Z) Lengthening of the Central Slip

Step 1

image A step-cut lengthening of the central slip should be considered if shortening of the central slip restricts PIP joint flexion after manipulation of the PIP joint and mobilization of the lateral bands has been attempted.

image A Z-incision of the central slip is made beginning 3 to 4 mm proximal to the insertion at the middle phalanx (marked as black dot on figures) and extended 1 to 1.5 cm proximally (depending on the severity of the deformity) (Fig. 33-13A).

image

FIGURE 33-13

Step 2

image A dorsal joint release including the capsule and dorsal part of the collateral ligaments is carried out (Fig. 33-13B).

Step 3

image The PIP joint is positioned in slight flexion, and the lengthened central slip is repaired using multiple horizontal mattress sutures (Fig. 33-13C).

Step 3 Pitfalls

An extension deficit of the PIP joint often develops after step-cut lengthening of the central slip. To prevent rupture of the repair and facilitate early mobilization, the length of the step cut should allow at least three or four sutures.

Postoperative Care and Expected Outcomes

image Active motion should be encouraged as early as the second postoperative day.

image A dorsal extension block splint is used for 2 weeks until the surgical wounds have healed. This is followed by a thermoplastic figure-of-eight splint for an additional 8 weeks.

image After manipulation of the PIP joint or mobilization of lateral bands for a type III deformity, the PIP joint should be kept in flexion with a splint for 1 or 2 weeks to stretch the dorsal soft tissue. Patients should continue active flexion except in cases that also required central slip lengthening. These patients should be immobilized for 3 to 4 weeks.

image The results of surgery are unpredictable for advanced swan-neck deformity, and the percentage of good results is small. However, even if motion is lost, the flexed position of the PIP joint is functionally much better than the hyperextended position. Therefore, one must not hesitate to perform surgery for advanced swan-neck deformity as long as PIP joint hyperextension can be prevented.

image Figure 33-14 shows the appearance of the patient in Figure 33-2 one year after surgery. The patient underwent release of the ulnar intrinsic muscle, manipulation of the PIP joints, tenodermodesis of the DIP joint of the index and small fingers, and lateral band mobilization and volar plate reconstruction using bone anchors for the long and ring fingers. The swan-neck deformity was corrected, and all fingers had reasonable flexion except the small finger where the deformity recurred.

image Figure 33-15 shows a stiff swan-neck deformity with MP flexion-contractures of all fingers in a 49-year-old woman. She underwent intrinsic muscle release and lateral band mobilization of all fingers. In addition, lengthening of the central slip was done for the long and ring fingers. An extension block pin was inserted into the head of the proximal phalanx to protect the central slip repair, and the distal wounds were left open. Excellent flexion of the PIP joint in 6 months (Fig. 33-15C) and at the10-year follow-up showed that the correction of the deformity was maintained (Fig. 33-15D and 33-15E).

image

FIGURE 33-14

image

FIGURE 33-15

Acknowledgment

We would like to thank Shimpei Ono, MD, for use of Figure 33-3.

Evidence

de Bruin M, van Vliet DC, Smeulders MJ, Kreulen M. Long-term results of lateral band translocation for the correction of swan neck deformity in cerebral palsy. J Pediatr Orthop. 2010;30:67-70.

The authors treated 62 fingers with lateral band translocation and reported a 84% success rate at 1 year, which declined to 60% at 5 years. The authors concluded that lateral band translocation should not be considered a long-lasting procedure in the treatment of cerebral palsy. (Level IV evidence)

Kiefhaber TR, Stricland JW. Soft tissue reconstruction for rheumatoid swan-neck and boutonniere deformities: long term results. J Hand Surg [Am]. 1993;18:984-989.

Ninety-two swan-neck deformities in rheumatoid patients were treated with dorsal capsulotomy and lateral band mobilization. The authors concluded that the results were unpredictable, and PIP motion deteriorated over time. (Level IV evidence)

Ozturk S, Zor F, Sengezar M, Isik S. Correction of bilateral congenital swan-neck deformity by use of Mitek mini anchor: a new technique. Br J Plast Surg. 2005;56:822-825.

Four congenital swan-neck deformities were successfully treated with reinforcement of the volar plate using the Mitek Mini anchor system. Two sutures of the anchor system crossed the PIP joint in a V fashion; the anchor was inserted into the volar surface of the proximal phalanx, and two sutures were passed through two holes created at the palmar proximal aspect of the middle phalanx. The sutures were tied to each other with the PIP joint in 20 degrees flexion. (Level IV evidence)

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