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Mallet Finger Abstract Mallet finger involves loss of continuity of the extensor tendon over the distal interphalangeal joint. This common hand injury results in a flexion deformity of the distal finger joint and may lead to an imbalance between flexion and extension forces more proximally in the digit. Mallet injuries can be classified into four types, based on skin integrity and the presence or absence of bony involvement. Although various treatment protocols have been proposed, splinting of the distal interphalangeal joint for 6 to 8 weeks has yielded good results while minimizing morbidity in the majority of patients. Surgical management may be considered for acute and chronic mallet lesions in patients who have failed nonsurgical treatment, are unable to work with the splint in position, or have a fracture involving more than one third of the joint surface. F ingertip injuries are among the most common traumatic problems encountered by hand surgeons. One such injury, which involves disruption of the extensor mechanism at the level of the distal interphalangeal (DIP) joint, is commonly re- ferred to as a mallet, baseball, or drop finger. 1,2 The term mallet finger originated during the late nineteenth century, in reference to a frequently seen sports-related flexion defor mity of the fingertip. 3 The injury is now known to occur in association with any activity leading to forced flexion of the DIP joint. Recognition and diagnosis of a mallet finger are relatively straight- forward. Treatment requires careful attention to detail by the surgeon and diligent patient compliance to restore function and avoid complications. Knowledge of the complex anatomy of the extensor mechanism of the finger is essential, as is a thor- ough understanding of how a disruption at the DIP joint level can upset the delicate balance of extension and flexion forces more proximally. Al- though most mallet injuries can be successfully managed nonsurgically, surgery is occasionally recommended for treatment of either an acute or a chronic mallet finger or for salvage of failed prior treatment. Epidemiology Mallet finger injuries usually occur in the work environment or during sports participation. 2 The most frequently involved digits are the long, ring, and small fingers of the domi- nant hand. 1 The lesion is often seen in young to middle-aged males; women with this injury tend to be older. Although most mallet fingers are caused by a traumatic event, Jones and Peterson 4 found an unusu- ally high incidence in a three- generation family, with 85% of the lesions developing spontaneously or after minimal trauma. The authors proposed a possible genetic predispo- sition toward mallet finger deformity in certain individuals. Anup A. Bendre, MD, Brian J. Hartigan, MD, and David M. Kalainov, MD Dr. Bendre is Orthopaedic Surgeon, OAD Orthopaedics, Warrenville, IL. Dr. Hartigan is Assistant Professor of Clinical Orthopaedic Surgery, Department of Orthopaedic Surgery, Northwestern University, Feinberg School of Medicine, Northwestern Center for Orthopedics, Chicago, IL. Dr. Kalainov is Assistant Professor of Clinical Orthopaedic Surgery, Department of Orthopaedic Surgery, Northwestern University, Feinberg School of Medicine, Northwestern Center for Orthopedics. None of the following authors or the departments with which they are affiliated has received anything of value from or owns stock in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Bendre, Dr. Hartigan, and Dr. Kalainov. Reprint requests: Dr. Bendre, OAD Orthopaedics, 27650 Ferry Road, Warrenville, IL 60555-3 845. J Am Acad Orthop Surg 2005;13:336- 344 Copyright 2005 by the American Academy of Orthopaedic Surgeons. 336 Journal of the American Academy of Orthopaedic Surgeons Anatomy The anatomy of the extensor tendon of the finger has been well described 1,2,5-7 (Fig. 1). The extrinsic extensor tendon originates in the forearm and courses over the finger metacarpophalangeal (MCP) joint. The extrinsic extensor tendon has an indirect attachment to the proximal phalanx, such that the primary extensor force across the MCP joint is transmitted through the sagittal band connections to the volar plate. The extrinsic tendon continues distally and trifurcates over the proximal phalanx. The central continua- tion of the extensor tendon (ie, the central slip) attaches to the dorsal base of the middle phalanx, exerting an extensor force across the proximal interphalangeal (PIP) joint. The interosseous and lumbrical muscles provide the intrinsic contri- bution to the extensor mechanism. These muscle-tendon units form a lateral band on each side of the digit, passing volar to the MCP joint. The lateral bands join with the lateral slips of the extrinsic extensor tendon at the level of the PIP joint to form the conjoined lateral bands. The two conjoined lateral bands then converge dorsally and insert at the base of the distal phalanx as the terminal extensor tendon. The other components of the extensor apparatus stabilize the extensor hood and coordinate joint move- ment. The triangular ligament is a thin tissue connecting the conjoined lateral bands over the middle phalanx. This structure prevents separa- tion and volar migration of the lateral bands when the PIP joint is flexed. The transverse retinacular ligaments originate from each side of the PIP joint volar plate, inserting dorsally into the adjacent conjoined lateral band. These ligaments stabilize and limit dorsal migration of the lateral bands during PIP joint extension. The oblique retinacular ligaments arise from the flexor tendon sheath and volar aspect of the proximal phalanx. They course distally to inser t onto the dorsal base of the distal phalanx with the terminal extensor tendon, thus linking and coordinat- ing PIP and DIP joint motion. Mechanism of Injury and Pathoanatomy Mallet finger most commonly is caused by sudden forced flexion of the extended fingertip, resulting in either stretching or tearing of the extensor tendon substance or avulsion of the tendon insertion from the dorsum of the distal phalanx, with or without a fragment of bone. Open injuries are caused by a laceration, crush, or deep abrasion. A less frequent mechanism of injury involves Figure 1 Finger extensor mechanism anatomy. A, Lateral view. B, Dorsal view. DIP = distal interphalangeal joint, MCP = metacarpophalangeal joint, ORL = oblique retinacular ligament, PIP = proximal interphalangeal joint, TRL = transverse retinacular ligament. (Adapted with permission from Coons MS, Green SM: Boutonniere deformity. Hand Clin 1995;11:387-402.) Anup A. Bendre, MD, et al Volume 13, Number 5, September 2005 337 forced hyperextension of the DIP joint with a resultant fracture at the dorsal base of the distal phalanx. 2 The functional anatomy of the finger represents a well-balanced system between intrinsic and extrinsic tendons, and between flexion and extension forces across each finger interphalangeal (IP) joint. Kaplan 5 recognized that any injury causing a flexion or extension deformity in one IP joint can lead to tendon imbalance, creating an opposite deformity in the adjacent IP joint (Fig. 2). At the DIP joint, the flexor digitorum profundus flexion force is counterbalanced by the terminal extensor tendon. At the level of the PIP joint, the flexion forces of the flexor digitorum profundus and superficia- lis tendons are counterbalanced by the extension forces of the conjoined lateral bands and the central slip of the extensor apparatus. With a mallet injury, the delicate balance between flexion and extension forces is disrupted. The discon- tinuity of the terminal extensor tendon allows the extensor apparatus to migrate proximally, thus increasing extensor tone at the PIP joint rela- tive to the DIP joint. The resulting imbalance can lead to an early or late swan neck deformity (hyperextension of the PIP joint with concomi- tant flexion of the DIP joint). Classification Acute mallet deformities have been arbitrarily defined as those occurring within 4 weeks of injury; chronic deformities are those presenting later than 4 weeks from injury. 8,9 The classification scheme developed by Doyle 2 divides mallet injuries into four types (Table 1). Type I lesions involve closed trauma to the fingertip, with or without a small avulsion fracture at the dorsal base of the distal phalanx, resulting in loss of terminal extensor tendon continuity. Type II injuries are open tendon injuries caused by laceration at or around the DIP joint. Type III lesions are also open injuries; they occur from a deep soft-tissue abrasion with loss of skin and tendon substance. Type IV lesions present as mallet fractures and are subclassified into three types. Type IVA lesions are distal phalanx physeal injuries in children. Type IVB lesions are distal phalanx fractures in adults involving 20% to 50% of the joint surface. Type IVC injuries are caused by hyperextension, resulting in a fracture fragment measuring >50% of the distal phalanx articular surface; they are associated with DIP joint volar subluxation. This subclassification of mallet fractures corresponds to the categorization scheme proposed by Damron and Engber. 10 Wehbé and Schneider 11 developed their own classification system for type IV injuries based on fracture size and presence or absence of DIP joint subluxation. Clinical Evaluation Diagnosis of a mallet finger is relatively uncomplicated. Patients present with pain, deformity, and/or difficulty using the affected finger. 1 Posteroanterior, oblique, and lateral radiographs of the digit are recommended to assess for bone injury and joint alignment. The examination begins with an inspection of the soft tissues as well as measurements of finger MCP and PIP joint motion. In acute injuries, tenderness is elicited with palpation over the dorsal mar- gin of the DIP joint. Although most patients develop an extensor lag at the DIP joint immediately after injury, the deformity may be delayed by a few hours or even days. Concur- rent hyperextension of the PIP joint (ie, swan neck posture) may be noted with active finger extension. Management of Acute Mallet Finger Injuries Several options are available for managing acute mallet finger inju- Figure 2 Lateral view demonstrating the balance between flexion and extension forces at the finger joints. The single dots represent the axes of flexion-extension at each joint. The double dots represent the areas of action of the corresponding tendons at each joint. (Adapted with permission from Kaplan EB: Anatomy, injuries and treatment of the extensor apparatus of the hand and digits. Clin Orthop 1959;13:24-41.) Doyle’s Classification of Mallet Finger Injuries 2 Type Description I Closed injury, with or without small dorsal avulsion fracture II Open injury (laceration) III Open injury (deep abrasion involving skin and tendon substance) IV Mallet fracture A Distal phalanx physeal injury (pediatric) B Fracture fragment involving 20% to 50% of articular surface (adult) C Fracture fragment >50% of articular surface (adult) Table 1 Mallet Finger 338 Journal of the American Academy of Orthopaedic Surgeons ries, including reassurance, observation, splint immobilization, and surgery. Although there are no clearly established criteria for an acceptable result, Geyman et al 3 defined a satis- factory outcome as one in which the DIP joint exhibits a residual extensor lag ≤20°, the DIP flexion arc is ≥50°, and the patient reports minimal or no pain. Neglecting mallet injury often results in permanent stiff- ness and deformity at the DIP joint level. Although many splint config- urations and surgical techniques have been described over the last century, the optimal treatment of each type of mallet finger injury remains controversial. Nonsurgical Management Nonsurgical management has been the standard of care for type I mallet injuries as well as for closed mallet fractures involving less than one third of the articular surface with no associated DIP joint subluxation. However, differences of opin- ion exist regarding both the style of splint and the duration of immobilization necessary to achieve an acceptable outcome. Immobilization of both the PIP and DIP joints was previously thought to be necessary to relax the extensor hood and intrinsic muscu- lature during terminal extensor tendon healing. Katzman et al 12 performed a cadaveric study to deter- mine whether PIP joint motion would cause a tendon gap at the immobilized DIP joint. They demon- strated that gapping of a disrupted terminal extensor tendon occurred as a result of excursion of the distal tendon stump during DIP joint flexion, not because of retraction of the proximal portion of the tendon with simulated PIP joint extension. They concluded that only the DIP joint need be immobilized in extension to allow healing of the mallet injury. Most authors cur rently advocate immobilization of the DIP joint alone. 2,11,13 In the presence of a swan neck deformity , however, Wehbé and Schneider 11 and Evans and Weight- man 14 have suggested temporary inclusion of the PIP joint in flexion. Combined PIP and DIP joint splinting has not been conclusively proved to restore tendon balance in a swan neck deformity. Splinting Numerous splints have been devised for managing mallet finger injuries. 1-3 Common examples include the stack splint, the perforated thermoplastic splint, and the aluminum foam splint (Fig. 3). Wilson and Khoo 15 have reported their experi- ence with a novel splint design, which they termed the Mexican hat splint. This splint incorporates a “buckle” over the DIP joint to alle- viate undue pressure on the healing terminal extensor tendon. A steril- ized aluminum splint secured with sterile tape strips has been proposed to treat mallet injuries in operating room personnel. 16 Despite the many splints available, the principles of treatment remain constant. The involved digit is immobilized in full extension or slight hyperextension across the DIP joint. Excessive extension should be avoided because dorsal skin vascular compromise can occur when the joint is immobilized in more than 50% of the normal range for passive DIP joint hyperextension. 15 Patients are instructed on how to change the splint for periodic cleaning and examination of the skin without allowing the DIP joint to flex. Contin- uous immobilization is maintained for 6 to 8 weeks, followed by an ad- ditional 2-week period of nighttime splint use. A new full-length course of immobilization is recommended when the DIP joint is inadvertently flexed during treatment. Frequent physician assessment and patient compliance are fundamental for suc- cessful nonsurgical treatment. Two recent studies have provided information on the medium-term results of splint treatment of mallet injuries. 17,18 Okafor et al 17 used a stack splint to treat 31 patients with either a soft-tissue mallet injury or a mallet fracture. At 5-year follow-up, they noted a 90% patient satisfaction rate, with an average DIP joint extension deficit of only 8.3°. They concluded that a small residual extensor lag and radiographic evidence of DIP joint os- Figure 3 Three different mallet finger splints. A, Stack splint (Stax Finger Splint, Sammons Preston Rolyan, Bolingbrook, IL). B, Perforated thermoplastic splint (Aquaplast Splinting Material, Sammons Preston Rolyan). C, Aluminum foam splint. Anup A. Bendre, MD, et al Volume 13, Number 5, September 2005 339 teoarthritis did not preclude a suc- cessful treatment result. Foucher et al 18 advocated the use of a dorsal DIP joint extension splint made of perforated thermoplastic material. They assessed 78 patients at a mean of 5 years postinjury and noted a mean extensor lag of 5° and a mean active DIP joint flexion of 61°. The authors reported no skin complications, continued splint treatment, and reported no need for surgery in their study group. Casting In 1937, Smillie described casting of both IP joints to manage acute mallet finger injuries. 2 The plaster cast was applied with the PIP joint in 60° of flexion and the DIP joint in slight hyperextension. Inclusion of the PIP joint in flexion subsequently has been advocated as a means of preventing a tubular cast from inadvertently fall- ing off the finger. 19 Although this technique is infrequently used, casting may be beneficial in children and in individuals who are deemed non- compliant with splint treatment. Surgical Management Type I Injury Although splinting is the treatment of choice for most type I mallet finger injuries, surgery may be ad- vantageous for individuals who are unable to comply with a splinting regimen or for patients who would have difficulty performing their jobs with an external splint (eg, surgeons, dentists, musicians). 1,20 To immobilize the DIP joint in extension, a transarticular Kirschner wire (K- wire) is driven longitudinally or ob- liquely across the DIP joint, with the tip buried in the middle phalanx. The distal end of the wire is either capped or cut beneath the skin surface. The K-wire is removed after 6 to 8 weeks, followed by 2 weeks of nighttime extension splinting. Open Injuries (Types II and III) There are few published reports regarding the management of acute open mallet injuries. Nakamura and Nanjyo 20 described three patients who sustained lacerations over the DIP joint leading to permanent extensor lag measuring between 45° and 60°. They hypothesized that the large DIP joint extension deficits were caused by disruption of both the terminal extensor tendon and contiguous oblique retinacular ligaments. Allowing the extensor mechanism to heal by bridging the scar with splinting was thought to pre- dispose the digit to a DIP joint extensor lag and secondary swan neck deformity. Open surgical repair was recommended, using a wire secured around the DIP joint and a transarticular pin. Doyle 2 suggested a com- bination of surgical repair and splinting for acute tendon lacerations overlying the DIP joint. His technique involves a running suture to reapproximate both skin and tendon, followed by application of an extension splint. The suture is removed after 10 to 12 days, with splinting continued for 6 weeks. Type III mallet deformities, which involve loss of skin, subcuta- neous tissues, and tendon substance, are caused by deep abrasions, crush injuries, and degloving accidents. These lesions are often difficult to treat because of exposure of both bone and articular car tilage. Staged reconstructive surgery may be considered with the goal of providing early skin coverage, followed by restoration of extensor tendon function with insertion of a free tendon graft. 2 In severe cases, arthrodesis of the DIP joint with bone shortening or fingertip amputation may be more appropriate. Mallet Fracture (Type IV) Management strategies for the different subtypes of mallet fractures remain controversial. Treatment al- ternatives include observation with reassurance, extension splinting, closed and open reduction with internal fixation, and DIP joint arthrodesis. 2,11,21 A true lateral radiograph of the injured digit is valuable for determining the size and displacement of the fracture fragment as well as Figure 4 Calculations for determining fracture fragment size, fragment displacement, and distal interphalangeal joint subluxation. A and B = the length of the involved bone segments at the articular surface of the distal phalanx, C = the amount of fracture fragment displacement, D = the distance between the midaxial lines of the middle and distal phalanges. (Adapted with permission from Wehbé MA, Schneider LH: Mallet fractures. J Bone Joint Surg Am 1984;66:658-669.) Mallet Finger 340 Journal of the American Academy of Orthopaedic Surgeons the presence or absence of volar subluxation of the distal phalanx (Fig. 4). Most authorities agree that closed mallet fracture injuries involving less than one third of the articular surface and without DIP joint subluxation can be reliably treated with extension splinting alone. Wehbé and Schneider 11 and Schneider 19 advocated nonsurgical management of nearly all mallet fractures, regardless of the size or displacement of the fracture fragment or the presence of volar subluxation of the distal phalanx. They retrospec- tively reviewed 21 mallet finger fractures managed with either splinting alone or internal fixation of the fracture fragment using pins and a pullout wire. 11 Surgical treatment was technically demanding, with a higher complication rate than nonsurgical management. The only consistent complication in the nonsurgical group involved a dorsal prominence overlying the DIP joint; this same deformity was seen in the surgically treated patients. The authors also noted remarkable remodeling potential in the distal phalanx articular surface (Fig. 5). Additionally, the radiographic appearance of the DIP joint did not correlate with pain or finger function at final assessment. Many surgeons advocate surgical intervention for mallet fractures involving more than one third of the articular surface or for fractures with associated DIP joint subluxation. Various techniques have been described, including transarticular pinning of the DIP joint with or without fracture fragment fixation, tension- band constructs, 10,21,22 compression pinning, 23 and extension block pinning 24,25 (Fig. 6). All of these techniques involve placement of at least one K-wire to immobilize the DIP joint in extension. Proponents of open reduction think that associated complications can be minimized by using meticulous surgical technique. Closed reduction with percu- taneous pinning has been advocated by surgeons who are concerned about complications with open management. They cite problems related to reducing the small articular fragment, the inability to accurately assess DIP joint congruency, and the potential for injury to the tenuous soft-tissue envelope. 24,25 Management of Chronic Mallet Finger Injuries Patients who present for treatment more than 4 weeks after injury typically report pain, dissatisfaction with the appearance of the digit, and interference with use of the finger for normal work and recreational activ- ities. As with acute mallet injuries, both nonsurgical and surgical treatment measures have been advocated. Ten patients with chronic (4 to 18 weeks old) mallet finger injuries without swan neck deformity were treated with continuous extension splinting of the DIP joint for 10 weeks. 8 Extensor lag was corrected to <10° in all but one case. The only complication was a recurrent mallet posture in two patients after discon- tinuation of splint treatment, and both patients had an excellent result after reapplying the splint for 8 weeks. Patel et al 8 concluded that splinting should be considered as an alternative to surgery for a chronic mallet finger deformity. Garberman et al 9 found no differences in outcome between patients splinted early (<2 weeks after injury) and late (>4 weeks after injury). They recommended DIP joint extension splinting for closed mallet injuries regardless of chronicity, including fractures involving less than one Figure 5 Lateral radiograph of a remodeled mallet fracture. The arrows indicate the old fracture line. The distal interphalangeal joint remains congruent. Figure 6 Extension block pinning technique. A, With the distal phalanx extended, a Kirschner wire is inserted proximal to the fractured fragment. B, The fracture is reduced manually by directing the exposed end of the Kirschner wire distally. C, The wire is drilled into the head of the middle phalanx, and a second wire is passed retrograde across the distal interphalangeal joint. (Adapted with permission from Tetik C, Gudemez E: Modification of the extension block Kirschner wire technique for mallet fractures. Clin Orthop 2002;404:284-290.) Anup A. Bendre, MD, et al Volume 13, Number 5, September 2005 341 third of the joint surface. Brzezien- ski and Schneider 1 advocated splinting for all chronic mallet deformities resulting from either neglect or pre- vious failed treatment. Proponents of surgery argue that chronic mallet finger may develop pathologic features that interfere with treatment results. 13 A static contracture of the extensor mechanism can develop over time, making it difficult to achieve apposition of the tendon ends with simple extension splinting. Surgical procedures for chronic mallet finger deformities are intended to stabilize the DIP joint and improve active DIP joint extension. 20 Examples include terminal extensor tendon shortening, tenodermodesis, oblique retinacular ligament reconstruction, and Fow- ler’s central slip tenotomy. Lind and Hansen 26 described the abbreviato operation, in which the extensor tendon is transected near the DIP joint and repaired directly, without overlapping and without ex- cision of damaged tendon tissue. Scar contraction at the repair site is thought to cor rect the flexion deformity. The authors recommended performing the procedure within 3 months of injury in patients with marked ligamentous laxity to avoid progression to a swan neck deformity. However, the procedure is not recommended before 6 months to allow potential spontaneous correction of the extensor lag. Their technique includes using a transarticular pin to immobilize the DIP joint in extension for 6 weeks. Tenodermodesis, originally described by Iselin et al, 27 has been used to manage chronic mallet finger deformities in both adults and children. 28 This procedure involves resection of an elliptical wedge of skin, tendon, and scar tissue with re- approximation of the skin and tendon as a single unit with sutures (Fig. 7). Similar to the abbreviato operation, a temporary K-wire is used to maintain the DIP joint in full extension during the healing process. The spiral oblique retinacular ligament reconstruction procedure was devised to address the imbalance of flexion and extension forces contrib- uting to a chronic mallet deformity. This procedure, which restores the dynamic tenodesis effect of the oblique retinacular ligaments in coor- dinating PIP and DIP joint extension, was originally reported by Thompson et al 29 and was later mod- ified by Kleinman and Petersen. 30 A free tendon graft is harvested and secured distally to the dorsal base of the distal phalanx. The graft is passed volarward in a spiral fashion around the radial aspect of the middle phalanx and is secured proximally to the ulnar side of the flexor tendon sheath at the level of the proximal phalanx or directly to bone (Fig. 8). The PIP and DIP joints are temporarily immobilized with K-wires before initiating finger motion exercises. Fowler’ s central slip tenotomy cor- rects for increased extensor tone at the PIP joint resulting from retraction of the extensor apparatus (Fig. 9). Houpt et al 31 recommended delaying the operation until at least 3 months after injury to allow restoration of terminal extensor tendon continuity by scar tissue. To prevent boutonnière deformity, the triangular ligament bridging the two conjoined lateral bands must be preserved when cut- ting the extensor mechanism. 32 Un- like the other corrective procedures, active finger motion is permitted immediately after surgery. Arthrodesis is the primar y salvage procedure for patients with painful mallet finger injuries secondary to arthritis, deformity, infection, and/or failed prior surgery. Arthro- Figure 7 Tenodermodesis procedure in which a 3- to 4-mm elliptical wedge of skin, subcuta- neous tissue, and tendon/scar is resected. A, The full-thickness defect is repaired with nonabsorbable sutures. B, Before securing the sutures, the distal interphalangeal joint is immobilized in extension with a Kirschner wire. Mallet Finger 342 Journal of the American Academy of Orthopaedic Surgeons desis of the DIP joint can be effec- tively performed with K-wires, tension band wiring, or intramedullary screw fixation 33 (Fig. 10). The DIP joint is positioned between neutral and 10° of flexion. Arthrodesis pro- vides reliable pain relief and early PIP joint finger motion. Complications Stern and Kastrup 34 reported complications with nonsurgical and surgical management in 123 mallet finger injuries. They noted a 45% complication rate in the digits treated with extension splinting and a 53% complication rate in the digits treated surgically. Most of the complications from splinting were transient and resolved with adjustment of the splint or after completion of treatment. Complications included skin maceration and ulceration, tape al- lergy, transverse nail plate grooves, and splint-related pain. The only long-term splint complication was a transverse nail plate groove in one Figure 9 Dorsal (A) and lateral (B) views of Fowler’s central slip tenotomy. The central slip is transected immediately proximal to its insertion on the base of the middle phalanx. The lateral bands and triangular ligament are preserved. Figure 8 Spiral oblique retinacular ligament reconstruction. A, Lateral view. The tendon graft is secured to the dorsum of the distal phalanx with a pullout suture or wire. The graft is passed along the radial border of the middle phalanx, deep to the neurovas- cular bundle and volar to the flexor tendon sheath. B, Volar view. The graft is then sutured to the ulnar edge of the flexor tendon sheath at the level of the proximal phalanx. (Adapted with permission from Kleinman WB, Petersen DP: Oblique retinacular ligament reconstruction for chronic mallet finger deformity. J Hand Surg [Am] 1984;9:399-404.) Figure 10 Posteroanterior (A) and lateral (B) radiographs of a distal interphalangeal joint arthrodesis. Fixation was achieved with a headless differential-pitch compression screw. (Courtesy of Acutrak Headless Compression Screw System, Acumed, Hillsboro, OR.) Anup A. Bendre, MD, et al Volume 13, Number 5, September 2005 343 patient present after 2 years. In con- trast to the transient nature of the splint complications, 76% of the complications associated with surgical treatment were long-term. Re- ported problems included infection, nail plate deformity, joint incongru- ity, hardware failure, DIP joint prominence, and DIP joint deformity. Five surgically treated patients eventually underwent a second operation for pain. There were four DIP joint arthrodesis procedures and one fingertip amputation. Summary Mallet finger injuries are common and involve disruption of the terminal extensor mechanism overlying the DIP joint. Nonsurgical management with immobilization of the DIP joint in extension is the treatment of choice in the vast majority of cases. Management strategies for mallet fractures involving more than one third of the articular surface and/or fractures with volar subluxation of the distal phalanx remain controversial. Some authors have reported good functional results with nonsurgical management; others have proposed various surgical procedures to improve fracture and joint alignment. Although splint treatment is simple and associated complications typically are transient and benign, patient education, with careful attention to detail, is necessary to ensure an optimal outcome. Sur- gical correction of a mallet deformity may be elected based on the expe- rience of the treating surgeon with failure of nonsurgical management. Patients should be informed of the potential for a residual DIP extensor lag and swan neck finger deformity with all methods of treatment. References 1. Brzezienski MA, Schneider LH: Ex- tensor tendon injuries at the distal interphalangeal joint. Hand Clin 1995; 11:373-386. 2. Doyle JR: Extensor tendons—acute injuries, in Green DP, Hotchkiss RN, Pederson WC (eds): Green’s Operative Hand Surgery, ed 4. New York, NY: Churchill Livingstone, 1999, pp 1962- 1987. 3. Geyman JP, Fink K, Sullivan SD: Con- servative versus surgical treatment of mallet finger: A pooled quantitative literature evaluation. J Am Board Fam Pract 1998;11:382-390. 4. 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Stern PJ, Kastrup JJ: Complications and prognosis of treatment of mallet finger. J Hand Surg [Am] 1988;13:329-334. Mallet Finger 344 Journal of the American Academy of Orthopaedic Surgeons . lacerations over the DIP joint leading to permanent extensor lag measuring between 45° and 60°. They hypothesized that the large DIP joint extension deficits were caused by disruption of both the terminal. deformity was seen in the surgically treated patients. The authors also noted remarkable remodeling potential in the distal phalanx articular surface (Fig. 5). Additionally, the radiographic appearance. the small articular fragment, the inability to accurately assess DIP joint congruency, and the potential for injury to the tenuous soft-tissue envelope. 24,25 Management of Chronic Mallet Finger Injuries Patients