Benha M. J.. Vol. 26 No 1 Jan. 2009 MODIFIED EXTENSION BLOCK PINNING FOR LARGE MALLET FRACTURES Abdel-Salam A. Ahmed MD and Islam H. Hegazy MD Department oj Orthopedic Surgery. BenhaJaculty ojmedicine. Benha. Egypt Abstract Treatment of a mallet finger due to an intra-articular jracture of the distal phalanx involving one-third or more of the articular sulface is controversial. Twenty one malletjractures involving more than 33% ofthe articular surface and fractures associated with subluxation of the distal phalanx that could not be corrected by closed reduction are treated with an extension block pin and transarticular fixation of the distal interphalangeal joint. The average patient age was 26.8 years and the average fracture size was 40.5% ofthe joint sulface. The average delay after uyury was 5.6 days (range, 0-14 days) Average time to fracture union was 32 days. The average active flexion of the distal interphalangeal joint was 81.2 and the average extensor lag was 1.4. There were no major complications. Using the established outcome criteria for mallet uyuries, 95.2% had excellent or good results. This surgical technique resulted in rapid fracture union with only minor complications and has excellent functional outcome. Introduction an extended DIP joint, producing Mallet finger involves disrup detachment of the terminal extention of the extensor mechanism at sor mechanism or an avulsion the level of the distal interphalan fracture of the base of the distal geal (DIP) joint, is commonly re phalanx (Garberman et al.. 1994) ferred to as a mallet, baseball, or and (Okafor et al., 1997). The drop finger (Brzezienski and most frequently involved digits Schneider, 1995) and (Doyle. are the long. ring, and small fin 1999). The injury is now known to gers of the dominant hand (Brzeoccur in association. with any ac zienski and Schneider, 1995). The tivity leading to forced flexion of lesion is often seen in young to 407 "
Abdel-Salam A. Ahmed and Islam H. Hegazy --------- middle-aged males; women with this injury tend to be older. The classification scheme developed by Doyle (1999): divides mallet injuries into four types (Table 1). Type IV lesions present as mallet fractures and are subclassified into three types. Management strategies for the different subtypes of mallet fractures remain controversial (Anup et al., 2005). Nonsurgical treatment of displaced mallet fractures has been extensively reported and includes continuous rigid aluminum splinting, plaster casting. prefabricated splints. and custommade orthosis (Lester et al.. 2000) and (Hofmiester et ai., 2003). These treatments are not entirely benign. Complications, including joint stiffness, skin maceration. necrosis, loss of extension, and hyperextension deformity have been reported (Rayan and Mullins, 1987). Complications often are exacerbated by poor patient compliance, which results in extensor lag of greater than 10, swan neck deformity. and early osteoarthritic changes (Garberman et ai., 1994) and (Brzezienski and Schneider, 1995). Various suggested methods of surgical treatment include open reduction and use of a pullout wire to stabilize the fracture, open reduction and internal fixation (Stark et ai.. 1987). DIP joint pinning (Auchincloss, 1982), tension band wiring (Damron et ai.. 1993), (Damron and Engber. 1994) and (Bischoff et ai., 1994), extension block pinning (Ishiguro et al., 1997) and (Darder-Parts et al.. I 98). and compression pinning (Yamanaka and Sasaki, 1999). In 1988, Ishiguro described a method for closed reduction of mallet fr.j.ctures. This extension block Kirschner wire (K wire) technique minimizes complications of surgical treatment. Tetik and Gudemez (2002) modified the technique in 2002. The purpose of this study is to evaluate this technique for fixation of displaced mallet fractures with respect to outcome, associated complications, time to union. range of motion. and patient satisfaction. Patients and Methods Between 2006 and 2008. 21 patients with a mallet fracture in 21 patients - were treated in 2 centers. King Abd el-aziz central 408
Benha M. J. Vol. 26 No 1 Jan. 2009 hospital, Jeddah and King Fahad central hospital, Madinah. KSA, by Tetik and Gudemez modification of the extension block Kirschner wire technique. The study included closed, displaced mallet fracture with minimum fracture fragment on radiograph that was greater than 1/3 of the articular surface or a fracture associated with DIP joint subluxation. There were 16 men and 5 women. The average age of the patient was 26.8 years (range, 20-42 years), and the average delay after injury was 5.6 days (range. 0-14 days). The operation was performed within 1 week after injury in 11 patients and between the first and the second week in 10. The involved digits were 9 small fingers. 8 middle nngers. 3 ring fingers and one index finger. Seventeen injuries occurred in the dominant hand. About two thirds of the injuries occurred during athletic activities. (Fig. 1). The fractures involved a mean 40.5% of the articular surface (range. 33%-60%). Four fractures (19%) were associated with volar subluxation of the distal phalanx. Patients were followed 'up every 2 weeks with physical examination and radiographs. Fracture union was defined as a nontender DIP joint and bridging trabaculae on radiographs. Functional outcomes were determined by using the Crawford criteria (1984) (Table 2). Operative Technique : The procedure generally was done under digital block anesthesia and C-arm image intensifier control. While the distal phalanx was in the 0 extension position with reduction of subluxation if it exists, a K wire was inserted dorsally just proximal to the fractured fragment in a 45 proximal A true lateral radiograph of the to distal and dorsovolar direction, injured digit is used for determining the size and displacement of (Fig 2-A). For most adults, we pre aiming distally under the fragment the fracture fragment as well as,ferred to use la-mm (0.045- inch) the presence or absence of volar K-wiJ::eS, and for patients with subluxation of the distal phalanx small hands, we used 0.9-mm 409.,
Abdel-Salam A. Ahmed and Islam H. Hegazy (0.035-inch) K-wires. When the tip of the wire touched the head of the middle 'phalanx. the outside end of the wire was tilted 90 distally. With this maneuver. the fragment was pushed toward the fracture surface and reduced in the distal phalanx (Fig 2-B). When the reduction was verified by image intensifier control. the K wire was inserted through the head of the middle phalanx using a power drill. Then a second K wire was inserted (obliquely or longitudinally) from the tip of the distal phalanx into the middle phalanx to fix the distal interphalangeal joint (Fig 2-C). Congruity of the articular surface and reduction of the subluxation of the distal phalanx were verified. The wires were cut and a soft dressing was applied. A removable postoperative extension volar splint was placed to protect the pins and to block DIP motion; however. frequent removal of the splint for hygiene was encouraged. The patient was advised to keep the digit dry, and pin care was maintained. Patients were followed up at approximately 10 days and F as needed during the' next 4 weeks. The pins were removed in the outpatient clinic when bridging trabeculae were present and the fracture site was nontender., Immediately after pin removal. extension exercises of the DIP joint were done, and a volar DIP splint was placed to protect the joint for an additional 2 to 3 weeks. Progressive flexion was allowed during the ensuing weeks. Table 1: Doyle's Classification of Mallet Finger Injuries (1999) TYPE I II III Description Closed injury. with or without small dorsal avulsion fracture Open injury (laceration) Open injury (deep abrasion involving skin and tendon substance) IV Mallet fracture Fi{ A Distal phalanx physeal injury (pediatric) A, B- Frare fragment involving 20% to'50% of articular surface (adult) fra C- t=racture fragment >50% of articular surface (adult) Kil se Te 410
4 BenhaM.J. Vol. 26 No 1 Jan. 200Q /\ ci-<ifis n :t _..._=.. _ A -.:..."-':.t:,... -:,:. 1; --:: te I. P IS d d n - d. - t t r Fracture siz& = Displacement _.-- D...!!- (%) A+B --2-- (%) A... e.joint subluxallon --:;::;:e (%) Figure 1: 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 fraglllent displacement, D =the distance between the midaxial lines of the middle and distal phalanges. (Adapted from Wehe and Schneider, 1984 ). Table 2. Crawford Classification Classlncatlon extension Loss Flexion Pain Excellent None Full None Good 0" to 10' Full None Fair 10 to 25" Any loss of flexion None - Poor > 25" Any loss of flexion Persistent pain... A..... --<'.. a c Figure 2: 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 from Tetlk and GUdemez_ 411
BenhaM. J. Vol. 26 No 1 Jan. 200Q pplied. A ci Ftacture slz.. = B (%) A+S xtension... L o protect motion; al of the ouraged. to keep care was. followed t_:=':.' ;:""'!t Displacement 0 (%) K. A _... ""i:.,.\.-;' A+B Joint subluxation c -;;::;:s (%0) ays and Figure 1.: Calculations for determining fracture fragment size, fragment displacement. and next 4 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 oved in of fracture fragljlent displacement, D =the distance between the midaxial n bjidg lines of the middle and distal phalanges. (Adapted from Wehbe and ent and Schneider, 1984 ).. )ntender. Table 2, Crawford Classification OYal, ex DIP joint Classification Extension Loss Flexion Pain IP splint Excellent None Full None Good 0" to 10' Full joint for None eks. Pro Fair 10' to 25' Any 105S of flexion None i1i7ed dur- Poor >25' Any loss of flexion Persistent pain...) A. A. "...;..-.. c ' " _., I Figure 2: Extension block pinning technique: 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 from Tetik and Gudemez 411 \