Mallet Figer dnbid lecture 2012

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Mallet Finger

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Mallet Finger :

Mallet Finger dnbid

PowerPoint Presentation:

Loss of extensor tendon continuity at the distal interphalangeal joint (DIPJ) causes the joint to rest in an abnormally flexed position, as shown below. This occurs with a laceration to the dorsum of the digit near the DIPJ. Mallet finger describes the condition in which the skin remains closed and the extensor tendon is either forcibly stretched or avulsed from the distal phalanx.

PowerPoint Presentation:

Despite active extension effort, the distal interphalangeal joint of the index finger rests in flexion, characteristic of a mallet finger.

Problem :

Problem The terminal portion of the extensor mechanism that crosses the distal interphalangeal joint (DIPJ) in the midline dorsally is responsible for active extension of the distal joint. A flexion force on the tip of the extended finger jolts the DIPJ into flexion. This may result in a stretching or tearing of the tendon substance or an avulsion of the tendon's insertion on the dorsal lip of the distal phalanx base. In either instance, active extension power of the DIPJ is lost, and the joint rests in an abnormally flexed position (mallet finger), as shown below.

PowerPoint Presentation:

Despite active extension effort, the distal interphalangeal joint of the index finger rests in flexion, characteristic of a mallet finger.

Epidemiology :

Epidemiology Frequency Several different athletic injuries can occur at the interphalangeal joints. The most common injury is a sprain of the proximal interphalangeal joint (PIPJ), the so-called jammed finger . Mallet fingers are less common than PIPJ sprains, but they are more common than PIP fractures or fracture dislocations. Similar injuries to the extensor mechanism at the interphalangeal joint of the thumb occur, although infrequently.

Etiology :

Etiology Any forced flexion of the finger while it is held in an extended position risks the integrity of the extensor mechanism at the distal interphalangeal joint (DIPJ). The classic mechanism of injury is a finger held rigidly in extension or nearly full extension when the finger is struck on the tip by a softball, volleyball, or basketball. Other common mechanisms of injury include forcefully tucking in a bedspread or slipcover or pushing off a sock with extended fingers.

Pathophysiology :

Pathophysiology From experimental studies, the rate of loading determines whether a tendon (or ligament) ruptures in mid substance or is avulsed from its bony attachment. Rapid loading rates are more likely to cause a tear in the tendon itself. Lower loading rates are more likely to cause a bony avulsion. This occurs because the bone is relatively more viscoelastic than the tendon.

Presentation :

Presentation Following a forced distal interphalangeal joint (DIPJ) flexion injury, the patient notices the inability to actively extend the distal joint, although full passive extension remains intact. The dorsum of the joint may be slightly tender and swollen, but often the injury is painless or nearly painless. Patients may think that the joint is only sprained. They continue playing sports and notice loss of active extension after 1 or more days.

PowerPoint Presentation:

Patients may not present to the orthopedist with mallet finger for weeks or even months, perhaps having received no treatment or ineffective treatment. Bony injuries heal within weeks; thus, an old bony injury without functional deficit is best left untreated. A tendinous injury generally can be improved by extension splinting up to 6 months from the time of injury. The period of splinting for such an old injury is extended because the area becomes less inflamed as time passes. Therefore, fibroplasia and wound contraction occur more slowly and less completely.

Indications :

Indications Attempted open reduction and internal fixation (ORIF) of a mallet injury (mallet finger), either tendinous or bony, often results in a stiff, infected, or painful finger. When a large, bony fragment is observed, the surgeon instinctively wants to anatomically reconstruct the articular surface. Remember, however, this is a non-weight-bearing joint, and articular incongruity, which would not be tolerated in the ankle or knee, is well tolerated in the distal interphalangeal joint (DIPJ).

PowerPoint Presentation:

This joint has been demonstrated to remodel beautifully over time, even in the presence of volar subluxation of the distal phalanx. Late osteoarthritis at the DIPJ after an untreated mallet finger or a mallet finger that is treated without anatomic reduction of the fracture is rare, if not nonexistent. The risk of poor outcome from ill-advised open treatment far outweighs any risk of early dysfunction or late arthritis from splint treatment.

Contraindications :

Contraindications In most instances, the surgeon should resist any urge to treat these injuries surgically. (See the reasons listed in Indications.)

PowerPoint Presentation:

Imaging Studies Posteroanterior (PA) and lateral radiographs centered at the distal interphalangeal joint (DIPJ) of the affected finger are required, as shown below.

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This x-ray depicts a large, dorsal-lip avulsion fracture from the distal phalanx, a bony mallet injury.

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These radiographs are used to differentiate between a bony injury, as shown above, and a tendinous mallet injury, as well as reveal any associated metaphyseal , shaft, or tuft fractures of the distal phalanx. Perhaps most importantly, lateral radiographs reveal the presence of volar subluxation of the distal phalanx. These radiographic views also reveal rare condylar fractures of the middle phalanx. Radiographs of the whole hand do not suffice in evaluation of the mallet finger, as parallax of the x-ray beams creates an uninterpretable oblique view of the DIPJ. No other imaging studies are indicated.

Medical Therapy :

Medical Therapy Mallet injuries, whether bony or tendinous, should have closed treatment. [2, 3] This injured area is constrained tightly by adjacent unpadded skin dorsally, a tightly constrained hinge joint volarly , and the germinal matrix of the nail distally. Splinting of the distal interphalangeal joint (DIPJ) in full extension allows for healing of the injured structure and for restoration of excellent function and appearance, as shown below. [4]

PowerPoint Presentation:

A skin-tight plaster cast can effectively hold the distal interphalangeal joint extended and the proximal interphalangeal joint (PIP) flexed when a mallet deformity is accompanied by a hyperextensible PIP. Not immobilizing the PIP in partial flexion risks the development of a swan-neck deformity.

PowerPoint Presentation:

A stack splint is widely used for treatment of mallet finger.

PowerPoint Presentation:

Patient education and compliance are keys to good results. Once extension splinting has been initiated, it should be maintained without even a momentary lapse for the prescribed treatment period. Tendinous injuries require 6-8 weeks of splinting, and bony injuries require 4-5 weeks.

PowerPoint Presentation:

The time that is spent educating the patient regarding the necessity for nonstop protection in extension and techniques for maintaining joint extension (even when cleaning the finger and changing the splint) will be rewarded with favorable results.

PowerPoint Presentation:

The DIPJ should be immobilized in full extension so that the finger is straight. Sustained hyperextension of the DIPJ may cause ischemia to the skin over the dorsum of the joint and contribute to the development of pressure sores, as shown in the image below, which are occasionally observed as a result of tight splinting, especially in hyperextension. [5]

PowerPoint Presentation:

Pressure-sore formation can result from a splint that is applied too tightly, especially if the joint is maintained in a hyperextended position rather than a position of neutral extension.

PowerPoint Presentation:

Various means are available for holding the DIPJ in extension. Splinting can be isolated to the distal joint if the PIPJ is not lax and does not hyperextend. Splinting the proximal interphalangeal joint (PIPJ) in partial flexion for the first half of treatment is appropriate if the untreated finger assumes a swan-neck posture.

PowerPoint Presentation:

Small strips of aluminum with foam-rubber backing are commonly used. The foam backing should be of the closed-pore variety so that the foam does not absorb moisture. The open-pore form retains water in its interstices and harbors various microorganisms that hamper proper hygiene. Closed-pore foam aluminum strips are available from various orthopedic supply houses.

PowerPoint Presentation:

The aluminum strip can be applied either dorsally or volarly . Applied dorsally, the aluminum strip requires 2 strips of tape — one around the mid portion of the middle phalanx and one around the mid portion of the distal phalanx — for the splint to achieve 3-point fixation and maintain the distal joint in an extended position.

PowerPoint Presentation:

Dorsal splinting allows the digital pulp to be partially exposed for keyboarding and other daily activities. In addition, dorsal splints are more effective at maintaining the joint in full extension. Volar splinting requires only one band of tape around the finger at the level of the distal joint to achieve 3-point fixation. As such, the volar splint and single strip of tape are slightly easier to apply and maintain, but the aluminum precludes any tactile feedback from the digital pulp for light activities.

PowerPoint Presentation:

Other rigid materials can be used for makeshift splints. A large paper clip can be padded with adhesive tape and then used as a splint. Also, some patients have improvised temporary splints with plastic disposable spoons or sections of wooden ice-cream sticks.

PowerPoint Presentation:

Premolded plastic splints are available commercially; however, they often do not fit the finger sufficiently closely to maintain the joint in full extension. These splints have the added disadvantages of entirely covering and blinding the pulp from tactile sensation and preventing evaporation of moisture from the enclosed skin.

PowerPoint Presentation:

Having witnessed the shortcomings of the various splints as noted above, the author devised a simple, custom-molded plastic splint, as shown below. This splint leaves the pulp relatively exposed for functional activities, adheres closely to the contour of the digit without the need for tape, and is of sufficiently low profile to allow for evaporation of moisture from between the splint and the skin.

PowerPoint Presentation:

Blanks can be made from various thermoplastic materials that are routinely used by hand therapists or can be purchased commercially. The technique for applying this splint is demonstrated in a short video, below. (Contact George Tiemann & Co [25 Plant Ave, Hauppauge, NY, 11788; phone:   800-843-6266] to request more information or to purchase the Meals Custom Malleable Mallet Mender splint.)

PowerPoint Presentation:

(a) This photo demonstrates a thermoplastic blank for a custom-molded mallet finger splint and an oblique view of the molded splint in place. (b) Dorsal view of the custom-molded thermoplastic splint in place. (c) Volar view of the thermoplastic splint in place.

PowerPoint Presentation:

Regardless of the splinting method that is used, patients should have a follow-up appointment 1 week following the initiation of splinting to ensure that the joint is being properly maintained in extension and will continue as such. An adjustment in splint size may be necessary if any surrounding edema has subsided.

PowerPoint Presentation:

At the end of treatment (4-5 wk for bony injuries and 6-8 wk for tendinous injuries), the DIPJ should be stiff in full extension. Full-time splinting in extension for an additional 2-4 weeks is advised if an extensor lag is noted. If no extension lag is present and strength against resistance can be demonstrated, the patient should begin a slow weaning of the splint over the next 1-2 weeks. At that point, the splint should be used for 2-4 more weeks at night and with activities that put the joint at risk. The patient may then resume full activity. Specific finger exercises to regain flexion are very rarely required.

Surgical Therapy :

Surgical Therapy Many surgeons choose to operatively treat mallet injuries that are accompanied by volar subluxation of the distal phalanx; the belief is that restoring joint alignment and the balance between flexor and extensor forces is needed to obtain an adequate functional result in these patients. In general, the joint is reduced and a transarticular Kirschner wire (K-wire) is placed. If the fracture fragment cannot be held in reasonably close approximation to its insertion site, it may be stabilized with another K-wire or a pull-out suture technique. [6, 7, 8, 9, 10, 11, 12]

PowerPoint Presentation:

Occasionally, certain patients ( eg , surgeons, dentists) may be unable to wear splints for the required 6-8 weeks for vocational reasons. With a digital block, a .035-inch diameter K-wire can be inserted across the joint to serve as a temporary internal splint. Although the wire may help to maintain the reduction of a bony fragment, its primary purpose is to maintain extension of the joint. It can be difficult to get a K-wire to engage in the distal phalangeal tuft for a retrograde pinning.

PowerPoint Presentation:

Another option is to insert an oblique, antegrade K-wire by starting at the mid portion of the middle phalanx and placing the K-wire obliquely into the main body of the distal phalanx. By starting on the ulnar side of the digit, the wire can be clipped off just below the surface of the skin. The K-wire stabilization should be protected with an external splint when patients are not engaged in critical portions of their occupation. The K-wire can be retrieved and extracted under local anesthesia at the end of treatment.

Complications :

Complications The most bothersome complication from closed management of a mallet finger is a dorsal pressure sore over the distal interphalangeal joint (DIPJ). [2, 5] This results from excessive pressure of the splint or tape at that site and is probably potentiated by a hyperextension posture of the joint. This is not an instance in which if extension is good, hyperextension is better. Notice that the skin dorsally over the DIPJ blanches when the joint is held in a hyperextended position. [5]

PowerPoint Presentation:

Complications from open surgical management abound. Often, the small bony fragment is more comminuted than it appears on an x-ray, or it becomes comminuted during the effort at anatomic reduction and internal fixation. [2] Mobilization of the fragment in an effort to obtain an anatomic reduction can further devitalize the fragment and risk avascular necrosis . Infection, stiffness in extension, nail-bed damage, and chronic tenderness all are well-known problems of open treatment. [13]

Outcome and Prognosis :

Outcome and Prognosis An untreated mallet finger is rarely of functional consequence unless a secondary swan-neck deformity occurs. Even in those cases, patients rarely request surgical reconstruction, choosing instead to "live with it." With this in mind, treatment of a mallet finger should not be worse than the disease. An untreated mallet finger may be of some cosmetic consequence, but a finger of improved appearance with diminished function is not a wonderful outcome.

PowerPoint Presentation:

A functionally and cosmetically normal finger can be obtained with conservative treatment, as long as the patient understands the concept of nonstop extension splinting and is compliant with the care. [3] It may take several months following completion of splinting for local swelling and erythema to subside, but thereafter, appearance and motion are excellent.

PowerPoint Presentation:

Frequently, a faint residual extension lag is present, in the range of 5-10°, and is observable only on close scrutiny. Beware of the patient with naturally hyperextensible interphalangeal joints. Caution these patients at the outset that the best they can hope for is restoration of extension to neutral. They should not expect the degree of active hyperextension observed in their adjacent digits. This loss of complete extension is of no functional consequence and is of trivial cosmetic consequence.

PowerPoint Presentation:

Future and Controversies Although controversy exists regarding whether management of bony mallet injuries should be closed or open, especially when the dorsal avulsion fragment is large and the substance of the distal phalanx is subluxed anteriorly, the literature supports the concept of nonoperative treatment even in these cases. Better splints may be devised that allow more comfort and function while maintaining the affected distal joint in the necessary extension.

Ref::

Ref: http://emedicine.medscape.com/article/1242305-overview

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