Clinical Perspective Fracture Dislocations of the Proximal Interphalangeal Ioint

Thomas R. Kiefhaber, MD, Peter I. Stern, MD, Cincinnati, OH

The unprotected position and long moment arm of modalities be matched to fracture patterns? We ad- the proximal interphalangeal (PIP) joint make it vul- dress each of these issues below. nerable to injury. Some injuries are purely ligamentous, while others result in an intra-articular fracture Fracture Patterns with or without subluxation or dislocation. Unfortu- nately, clinicians and coaches often relegate PIP in- Proximal interphalangeal joint fracture disloca- juries to "nuisance status" and treat them with tions occasionally result from a pure extension or alarming casualness. As a result, patients are fre- flexion force; however, the majority occur when there is some component of longitudinal load. As an quently surprised and frustrated by suboptimal out- example, a bungled ball catch, a frequent cause of comes and persistent impairment. Permanent swell- PIP joint fracture dislocations, transmits a rapidly ing, pain, and variable degrees of stiffness often applied load containing substantial longitudinal force complicate adequate treatment of PIP joint injuries, vectors and strong angulatory moments. The applied and poorly designed or executed treatment frequently load direction and magnitude determine the fracture leads to marked stiffness, angulation, and degenera- location and pattern. Middle phalangeal articular tive changes. A thorough understanding of the forces fractures at the PIP joint occur in 3 anatomic loca- acting on the injured PIP joint, the desired treatment tions, including dorsal lip fractures, palmar lip frac- goals, and available treatment options allows the tures, and central articular disruptions (Fig. 1). There design of a therapeutic program that maximizes long- are 2 fracture mechanisms: avulsion and impaction term function. shear. Previous reports have addressed treatment of PIP Middle phalanx palmar lip fractures are the most joint fracture dislocation, but several theoretical and frequently encountered form of osseous injury asso- practical issues remain unresolved. Is complete cor- ciated with PIP joint fracture dislocations. Pure PIP rection of joint subluxation necessary? Must the frac- joint hyperextension nearly always disrupts the pal- tured joint surface be anatomically restored? What is mar plate either at its distal insertion or by creating a the role of early motion? How can diverse treatment tension fracture at the palmar lip of the middle phalanx. These avulsion fractures range in size from tiny bony flecks to fragments comprising one third of the From Cincinnati Hand Surgery Specialists, Cincinnati, OH; and the Department of Orthopaedic Surgery, University of Cincinnati, College joint surface. Displacement may be substantial, but of Medicine, Cincinnati, OH. avulsion fragments exhibit little comminution. In No benefits in any form have been received or will be received from contrast, a longitudinal load applied to the flexed 1 a commercial party related directly or indirectly to the subject of this article. PIP joint drives the proximal phalanx head into the Received for publication December 2, 1997; accepted in revised middle phalangeal base, shearing apart the articular form February 9, 1998. surface and then impacting fragments into the under- Reprint requests: Thomas R. Kiefhaber, MD, 2800 Winslow Ave, lying metaphyseal bone. Comminution of up to 80% Suite 401, Cincinnati, OH 45206. Copyright 1998 by the American Society for Surgery of the Hand. of the articular surface is common in these impaction 0363-5023/98/23A03-000253.00/0 shear injuries (Fig. 1A). Dorsal lip fractures also

368 The Journal of Hand Surgery The Journal of Hand Surgery/Vol. 23A No. 3 May 1998 369

Figure 1. Proximal interphalangeal joint fracture dislocation patterns. (A) Palmar lip fracture with dorsal subluxation. Palmar lip fractures can be of the avulsion or impaction shear type. In the impaction shear injury depicted here, the palmar 50% of the articular surface is damaged. The palmar plate remains attached to the anterior lip of the middle phalanx and there is impaction of articular cartilage into the underlying metaphyseal bone. Subtle dorsal subluxation is appreciated by observing a V-shaped gap between the articular surfaces of the head of the proximal phalanx and the undamaged portion of the middle phalanx base. (B) Dorsal lip fracture with palmar subluxation. Dorsal lip fractures can be of the avulsion or impaction shear type. Loss of middle phalangeal articular surface contour, as depicted in this impaction shear injury, accentuates palmar translation of the middle phalanx. (C) Pilon fracture.* By definition, pilon fractures include disruption of both the dorsal and palmar cortical margins. The central articular fragments are often comminuted and impacted into the underlying metaphyseal bone. (*Adapted from Kiefhaber TR. Phalangeal dislocations/periarticular trauma. In: Peimer CA, ed. Surgery of the hand and upper extremity. Vol. 1. New York: McGraw-Hill, 1996:963, with permission of The McGraw-Hill Companies.) 370 Kiefhaber and Stern / PIP Joint Fracture Dislocations occur by avulsion or impaction shear mechanisms. palmar plate arthroplasty 22-27 recommend the proce- Forced PIP joint hyperflexion results in central ten- dure as an excellent method of restoring joint con- don failure through its substance or at its bony at- gruency. tachment. Longitudinal load combined with PIP joint Finally, established investigators28'29 draw conclu- extension I creates a dorsal lip impaction shear frac- sions regarding correction of subluxation based on ture with characteristics similar to palmar injuries, a their clinical experience. Hastings and Carroll 19 re - rare fracture pattern in our experience (Fig. 1B). viewed 48 palmar lip fractures and summarized, A large, straightforward, longitudinal load crush- "Results parallel the accuracy of joint reduction- ing the middle phalangeal base is a pattern that Stern ... subtle incongruities in the matching articular et al.2 termed a "pilon" fracture. By definition, pilon surface of the proximal phalanx and the remaining fractures disrupt both the dorsal and palmar middle dorsal articular surface of middle phalanx lead to phalangeal cortical margins. Articular surface com- failure." In discussing dorsal subluxation associated minution is extensive, and the central fragments im- with PIP joint fracture dislocations, Bowers 3~ states, pact into the underlying metaphyseal bone (Fig. 1C). "A dorsally subluxed PIP joint cannot be expected to work properly, and it never will." Despite a few Is Joint Reduction Necessary? anecdotal reports of functional but subluxated PIP joints, 19'31 the preponderance of the literature sup- Middle phalangeal translation on the proximal ports anatomic PIP joint reduction. phalangeal head (i.e., PIP joint subluxation or dislo- In contrast to most other investigators, Schenck's3a cation) can be observed with dorsal or palmar lip report of the results of PIP joint fracture dislocations fractures. Is restoration of PIP joint congruency a treated with traction and early motion does not stress prerequisite for an acceptable clinical outcome? De- the importance of dorsal subluxation correction. His finitive studies comparing reduced and persistently traction method prevents collateral ligament contrac- subluxed PIP joint fracture dislocations are lacking, tures and allows middle phalanx articular surface re- but several investigators 3-s report poor results with modeling that leads to "good articular symmetry." We persistent subluxation. Hamer and Quinton3 reported believe that traction keeps the capsular structures dis- 27 PIP joint fracture dislocations treated with exten- tracted, allowing the middle phalanx to glide around the sion block splinting and noted a "less favorable proximal phalangeal head instead of hinging at the outcome" in 4 of the 5 joints that healed with slight fracture margin. A lateral radiograph in extension may dorsal subluxation. In a series of 7 PIP joint fracture reveal slight dorsal subluxation, but a second x-ray dislocations treated with a dynamic external fixator, obtained with the joint positioned in flexion demon- Inanami et al. 4 reported that the only patient experi- strates that the middle phalanx reduces and congruently encing posttreatment pain had persistent dorsal sub- glides around the proximal phalangeal head. Palmar luxation. Krakauer and Sterns reported 12 PIP frac- fragment consolidation restores stability and prevents ture dislocations treated with a dynamic hinged recurrent subluxation. external fixator. Three developed recurrent subluxa- Based on the literature and our experience, we tion, 1 progressed to bony ankylosis, and 2 exhibited conclude that successful PIP joint fracture disloca- advanced radiographic degenerative changes, lead- tion treatment restores the natural middle phalangeal ing to the conclusion that satisfactory outcome is glide around the proximal phalanx head and prevents predicated on first obtaining, and then maintaining, a hinging at the fracture margin. Proximal interphalan- congruously reduced joint. geal joint subluxation precludes a normal gliding Investigators favoring procedures or devices de- flexion arc and must be corrected (Fig. 2). signed to obtain reduction provide indirect evidence supporting congruous PIP joint reduction. Many Is Anatomic Reduction of the Joint methods of preventing recurrent subluxation or dis- Surface Necessary? location by limiting PIP joint extension have been described and include extension limiting splint- In theory, long-term PIP joint function should be ing, 3'6'7 extension block pinning, 8-1~ external fixa- enhanced by minimizing articular surface gaps or tion devices, 4"5'11-16 and skeletal traction. 16"17 Re- step off. Clinical experience supports anatomic re- searchers reporting open reduction and internal duction of intra-articular fractures in weight-bearing fixation techniques 18-21 include joint subluxation as joints such as the hip or knee. Knirk and Jupiter 33 their primary surgical indication, and proponents of and Bradway et al. 34 report a substantial reduction in The Journal of Hand Surgery / Vol. 23A No. 3 May 1998 371

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Figure 2. Proximal interphalangeal flexion/glide versus hinging. (A) Restoration of the normal glide of the middle phalanx around the head of the proximal phalanx requires complete elimination of middle phalangeal dorsal subluxation. (B) Hinging of the middle phalanx (depicted here) portends an unacceptable clinical result.

radiographically apparent posttraumatic degenerative studies lack comparison to joints allowed to heal changes when distal radius articular surface step offs with incompletely reduced articular surfaces. In a or separations are limited to -<2 mm. Should similar review of 16 PIP joint fracture dislocations treated guidelines be applied to PIP joint fracture disloca- with extension block splinting, Hamer and Quinton 3 tions? blame 5 cases with poor results on the presence of a Surprisingly, few investigators recommend ana- depressed middle phalanx central fragment; how- tomic joint surface reduction. Proponents of open ever, they also note that these joints exhibited dorsal reduction and internal fixation 18a9'21 report good re- subluxation, thus leaving in doubt whether the unac- suits after anatomic surface reconstruction, but these ceptable outcome resulted from articular irregularity 372 Kiefhaber and Stern / PIP Joint Fracture Dislocations

or persistent PIP joint subluxation. Proponents of the a phenomenon also observed by others.l~ ,36 Morgan palmar plate arthroplasty note that this procedure et al. 16 treated 5 pilon fractures with skeletal traction allows resurfacing of irregular, fractured articular and early range of motion; 4 became pain free and 1 cartilage with the smooth palmar plate. 23-25 Malerich had activity related mild discomfort. Two of and Eaton 22 state, "Incongruities or irregularities of Schenck' s 32 10 PIP joint fracture dislocations treated these surfaces inevitably lead to decreasing motion with skeletal traction demonstrated 100% articular and pain," but their statement is not supported by surface involvement and fit the definition of a pilon clinical data. fracture. Both did well even though there was lack of Most laboratory and clinical reports support the anatomic joint surface reduction. We conclude that concept that anatomic surface restoration is unnec- anatomic joint surface restoration is unnecessary if essary if subluxation is corrected and motion is in- subluxation is fully corrected and early motion is stituted shortly after injury. Salter's 35 laboratory instituted. studies demonstrate that continuous passive motion has a profoundly positive effect on cartilage healing. Treatment Guidelines The practical applicability of Salter's work to PIP We have established the following guidelines in joint fracture dislocations is demonstrated by numer- our treatment of PIP fracture dislocations: ous clinical reports illustrating good outcomes obtained by accepting incomplete articular reduction 1. Restoration of the middle phalangeal glide around the and instituting early motion. Agee 15 reported that 7 proximal phalangeal head during the flexion arc is of 16 patients treated with a force couple and imme- paramount. Hinging at the fracture site must be diate motion had an excellent outcome in spite of avoided. To accomplish this goal, the surgeon must unreduced central fragments. Schenck32 reported 10 eliminate joint subluxation and then re-establish joint stability to prevent recurrent subluxation. PIP joint fracture dislocations treated with traction 2. Early motion should be initiated whenever possible. and passive motion, and illustrated 2 joints that re- This enhances cartilage and soft tissue healing and gained a nearly full arc of pain-free motion despite minimizes adhesions or contractures. persistent articular surface irregularities. Morgan et 3. Anatomic restoration of the fractured joint surface is al. 16 reported 14 comminuted PIP joint fracture dis- a desirable but much less important treatment goal. locations treated with traction and immediate motion, and noted that persistent central fragment Classification depression did not adversely affect outcome. Addi- tional evidence is found in several articles that illus- A useful classification should help select the sim- trate cases depicting successful treatment of PIP plest treatment that restores a concentric stable joint, joint fracture dislocation despite persistently de- initiates early motion, and obtains the best, most pressed middle phalangeal joint surface frag- practical joint surface reconstitution. Understanding ments.3,4,7,8,10,11,17,31 the forces acting on the injured joint allows injury Reports of pilon fractures provide the most com- classification based on stability and the selection of pelling evidence against the necessity of anatomic treatment that neutralizes the deforming forces. We joint surface reduction. Stem et al. 2 compared the have divided PIP joint fracture dislocations into 3 results of pilon fractures treated with splint immobi- broad categories based on the location of the middle lization, open reduction and internal fixation, or trac- phalanx articular fracture: dorsal lip, palmar lip, and tion. Of 4 splinted fractures, all experienced major pilon fractures. Each category is subdivided based on residual pain, 2 severe enough to warrant arthrodesis. the fracture pattern's postreduction stability (Table Seven of the 9 fractures treated with open reduction 1). Fractures within each subcategory are subjected and internal fixation resulted in persistent pain, 1 to identical biomechanical forces and require the requiring arthrodesis. Traction provided the best out- application of similar treatment principles to achieve come even though anatomic joint surface reduction an acceptable outcome. was not obtained. Four of the 7 pilon fractures treated with traction were pain free, none required Joint Stability additional surgery, and all recovered an acceptable Biomechanical studies 37 establish the palmar plate range of motion. Stern et al. also noted that the as the primary PIP joint palmar stabilizer; however, middle phalanx base remodeled, assuming a widened recurrent dorsal dislocation after palmar plate arthro- shape that matched the head of the proximal phalanx, plasty is a recognized complication that occasionally The Journal of Hand Surgery / Vol. 23A No. 3 May 1998 373

tionship 5'18'2~176 and predict dorsal instability Table 1. Stability-Based Classification of Proximal Interphalangeal Joint Fracture Dislocations when palmar lip involvement reaches 30% 43 or 40% 5"18"21"23"44"45 of the middle phalanx. Palmar lip fracture Does the palmar plate and ligamentous insuffi- Stable (<30% articular surface, reduced in extension) No PIP hyperextension ciency accompanying large fractures cause PIP joint Hyperextensible PIP (swan neck) instability or is the bony architectural alteration to Tenuous (30% to 50% articular surface and reduction blame? Wilson and Rowland 4~ and Zemel et al.46 maintained with <30 ~ flexion) advocated the use of osteotomy and bone grafting of Unstable (>50% articular surface or 30% to 50% requiring >30 ~ of flexion to maintain reduction) malunited palmar lip fractures to reestablish the cup- Dorsal lip fracture shaped middle phalanx articular contour to restore Stable (in extension) joint stability. Wilson and Rowland 4~ stated, "In Unstable (palmar translation of middle phalanx) Pilon fracture most fracture dislocations of this joint, however, the buttressing effect of the palmar lip must be restored PIP, proximal interphalangeal. before joint stability is assured." In summarizing the biomechanical importance of the middle phalanx palmar lip, Hastings and Car- roll 19 noted several factors that were responsible for occurs even when theprocedural details and postop- dorsal subluxation of the middle phalanx. When the erative immobilization protocol are accurately exe- cup-shaped middle phalanx articular surface is al- cuted. Eaton and Malerich 23 reported redislocation in tered by a palmar lip fracture, the dorsal-proximal to 1 case despite 3.5 weeks of immobilization. Hastings distal-palmar orientation of the remaining articular and Carroll 19 re-explored a re-dislocated palmar surface allows the central tendon to lift the middle plate arthroplasty and found the palmar plate firmly phalanx up and over the proximal phalanx head. The attached to the fracture bed, but the head of the middle phalangeal flexor digitorum superficialis in- proximal phalanx displaced into the underlying me- sertion site accentuates the joint's tendency to hinge taphyseal defect, allowing recurrent dorsal subluxa- at the fracture edge and further destabilizes palmar tion. At the 1992 American Society for Surgery of lip fractures (Fig. 3). This biomechanical model the Hand Annual Meeting, we reported 3 palmar combined with the available clinical evidence leads plate arthroplasties that re-dislocated after removal to 2 conclusions: a direct relationship exists between of the postoperative transarticular Kirschner wire palmar lip fragment size and dorsal instability, and (K-wire). In each case, the bony defect left by the restoration of stability requires reconstruction of an fracture was wider than the thickness of the palmar adequate middle phalanx palmar buttress. plate and settling was observed. We concluded that Fracture size and pattern are excellent predictors palmar plate reattachment per se does not restore of instability, but actual subluxation proclivity is best stability to PIP joint fracture dislocations. confirmed by physical examination. The surgeon can In his 1971 classification of PIP joint dislocations, test "unstressed instability ''27 of the PIP joint by Eaton as postulated stability loss when the "critical asking the patient to actively move the joint, follow- corner," the combined lateral collateral ligament and ing digital block anesthesia, through an arc of palmar plate insertion, separated from the middle motion, observing for clinical dislocation or sub- phalanx by avulsion or fracture. In a 1982 reclassi- luxation. Stability is confirmed by obtaining a post- fication, Eaton and Dray 39 recognized that fractures reduction lateral radiograph in full PIP joint exten- involving more than 40% of the middle phalanx sion. When subluxation is identified, the surgeon palmar joint surface are "unstable" and prone to determines the degree of flexion required to maintain recurrent dorsal subluxation. These investigators reduction, applies the chosen treatment method, and postulated that smaller, "stable" fractures are stabi- obtains a second radiograph to confirm reduction. lized by the few collateral ligament fibers that re- mained attached to the middle phalanx. The dorsal- Palmar Lip Fracture Classification palmar stability imparted by the collateral ligaments Previous classification systems quantify fracture is arguable, but Eaton's classification establishes a size and subluxation 47 or group PIP joint fracture direct relationship between the size of the middle dislocations into anatomic patterns. 48 Since our goal phalanx palmar lip fracture and postreduction sta- is to design a classification system that relates post- bility. Several other authors acknowledge this rela- reduction stability to treatment methods, we must go 374 Kiefhaber and Stern / PIP Joint Fracture Dislocations

Figure 3. Forces acting on palmar lip fractures. The extensor apparatus lifts the middle phalanx over the head of the proximal phalanx, a motion that is accentuated by the slope of the remaining undamaged middle phalangeal articular surface. Dorsal displacement is further accentuated by the distal lever arm of the flexor digitorum superficialis tendon. The only factors resisting dorsal migration of the middle phalanx are the palmar plate and the cup-shaped geometry of the middle phalanx base, stabilizers that are disrupted by palmar lip fractures. (Adapted from Kiefhaber TR. Phalangeal dislocations/periarticular trauma. In: Peimer CA, ed. Surgery of the hand and upper extremity. Vol. 1. New York: McGraw-Hill, 1996:957, with permission of The McGraw-Hill Companies.)

beyond fracture description alone and quantify functional stability. McElfresh et al. 6 and Hastings and Carroll 19 provide the foundation for our stability- based classification by stratifying PIP joint fracture dislocations according to the percentage of middle phalanx articular surface disrupted: 30% or less is presumed to be stable; 30% to 50% has tenuous stability; and more than 50% is an unstable joint (Fig. 4). We combine physical examination with Figure 4. Palmar lip fracture classification. Stable frac- fracture site quantification to functionally group PIP tures involve less than 30% of the articular surface and joint palmar lip fractures into 3 categories: stable, demonstrate no tendency to subluxate, even when the tenuous, and unstable. proximal interphalangeal (PIP) joint is fully extended. Stable. Stable fracture dislocations involve less that Tenuous fractures involve 30% to 50% of the middle 30% of the middle phalanx palmar lip and are stabile in phalangeal articular surface but remain reduced when the full PIP joint extension. Because the rare, small palmar joint is flexed to --<30~ . All PIP joint fractures involving -->50% of the joint surface are categorized as unstable. lip fracture allows dorsal subluxation, ~8'2~ stability Fractures involving 30% to 50% of the middle phalangeal should be confirmed by radiographically demonstrating base that require more than 30 ~ of flexion to maintain congruent reduction with the PIP joint in full extension. reduction are also classified as unstable. (Adapted from Stable palmar lip fractures are subdivided into 2 groups, Kiefhaber TR. Phalangeal dislocations/periarticular those in which the PIP joint actively hyperextends trauma. In: Peimer CA, ed. Surgery of the hand and upper (swan-neck deformity) and those that extend only to extremity. Vol. 1. New York: McGraw-Hill, 1996:958, neutral. with permission of The McGraw-Hill Companies.) The Journal of Hand Surgery / Vol. 23A No. 3 May 1998 375

Tenuous. When 30% to 50% of the middle pha- on the observation that dorsal subluxation usually lanx joint surface is fractured, stability is tenuous and corrects with PIP joint flexion. A short arm cast with can only be determined by clinical testing. Joints that a dorsal extension block outrigger allows full active reduce with --<30~ of flexion remain in the tenuous PIP joint flexion but blocks extension, thus maintain- group. Joints requiring more than 30 ~ of flexion are ing the joint in a reduced position. Other investiga- assigned to the unstable category. tors have modified the splint design, 3'5~ but did not Unstable. All PIP joint fractures involving ->50% change the principles of maintaining reduction with of the joint surface are categorized and treated as PIP joint flexion and allowing early motion. Others unstable, as well as 30% to 50% fractures that re- use the same concept, but provide the extension quire more than 30 ~ of flexion to maintain reduction. block with a K-wire protruding from the proximal phalanx head. 3'8"9 Dorsal Lip Fracture Classification The stability-based palmar lip classification and Longitudinal Traction Devices treatment principles also apply to dorsal lip fractures. Robertson et al. 17 designed a 3-pin traction device The joint must be reduced and the middle phalanx that applies PIP joint distraction through a middle articular contour restored to attain stability. Addi- phalanx pin, while 2 additional pins, 1 through the tionally, central tendon continuity must be reestab- proximal phalanx neck and the other through the lished, a task that usually requires immobilization in middle phalanx base, correct dorsal subluxation. extension. Because dorsal lip fractures are either Agee 14'15 proposed a force couple that maintains stable or unstable in full extension, the tenuous cat- joint reduction through a palmarly directed force egory is eliminated. applied to the middle phalanx while simultaneously Stable. Stable dorsal lip fractures are those in allowing active motion. Schenck 32 and Morgan et which the PIP joint is positioned in full PIP extension al.16 capitalize on the benefits of early motion by and there is no palmar subluxation. The fracture using traction devices that allow both longitudinal pattern may be of the avulsion or impaction shear distraction and passive PIP joint motion. Other ex- type and involve up to 50% of the joint surface; but ternal devices provide static immobilization, 3~ apply a lateral radiograph in full extension demonstrates a longitudinal force alone, 11 or combine traction with that the middle phalanx palmar articular surface re- a subluxation controlling palmarly directed force. 4 mains in congruous contact with the proximal pha- Dynamic external fixators designed by Hastings and lanx head. Ernst44 and Kasparyn and Hotchkiss 51 allow imme- Unstable. All fractures that allow middle phalan- diate active motion while maintaining longitudinal geal palmar translation when the PIP joint is in traction and subluxation correction. extension are classified as unstable, regardless of size or comminution. Open Reduction and Internal Fixation Treatment Options Open reduction and internal fixation has limited Proximal interphalangeal joint fracture dislocation applicability. It can be used to fix a noncomminuted treatment methods are grouped into 5 broad catego- fragment that is sufficiently large to stabilize with small lag screws or K-wires. 2~176 Pull-out su- ries: static immobilization, dorsal extension block splinting, longitudinal traction, open reduction and tures, 18'4~ tension banding, 52 or a combination of internal fixation, and palmar plate arthroplasty. techniques secure the more commonly encountered small comminuted fragments. Elevation of impacted Static Immobilization fragments often leaves a metaphyseal void that can Splint 49 or transarticular K-wire 19'3~ static immo- be filled with cancellous bone graft. 5'18"2~ bilization is simple but must be used judiciously. Palmar Plate Arthroplasty Articular reduction must be serially monitored by x-ray, and immobilization for more than 3 weeks Malerich and Eaton 22'23 designed and others have may result in permanent stiffness. used 24'25 an ingenious procedure for the treatment of dorsal fracture dislocations. The palmar plate is ad- Dorsal Extension Block Splints vanced into the middle phalanx fracture defect, si- McElfresh and collegues 6'7 proposed a PIP joint multaneously restoring stability and resurfacing the dorsal fracture dislocation treatment program based damaged articular surface. Hastings and col- 376 Kiefhaberand Stern / PIP Joint Fracture Dislocations leagues, 19"44 Kiefhaber, 53 and Krakauer and Stern 5 stores the middle phalanx palmar buttress. This can advocate replacing the originally proposed postoper- be accomplished in a number of ways. Static immo- ative K-wire immobilization with a dynamic external bilization with splint or transarticular wire predict- fixator to realize the benefits of early motion. ably restores stability, but deprives the joint and surrounding soft tissues of the benefits of early mo- Treatment of Palmar Lip Fractures tion. Open reduction and internal fixation, external If the hypothesis is accepted that restoring the fixation, and traction all require surgical intervention normal gliding motion of the middle phalanx around with possible complications. We avoid complex the proximal phalangeal head is a prerequisite to an treatments and recommend extension block splint- acceptable clinical outcome, then obtaining and ing. Regardless of the splint design, congruous joint maintaining a concentric joint reduction becomes the reduction must be assured by obtaining lateral radio- primary treatment goal. The classification system graphs with the joint extended to the limit allowed by outlined above groups palmar lip fractures based on the splint. Any dorsal subluxation of the middle predicted stability and allows selection of the sim- phalanx is unacceptable and must be corrected by plest treatment modality that restores stability and increasing the flexion angle. allows maximum motion. If 30 ~ of flexion fails to restore reduction, the injury must be reclassified as unstable and an appro- Stable Palmar Lip Fractures priate treatment method selected. The treatment program should be monitored carefully with serial lat- Stable palmar lip fractures do not cause PIP joint eral radiographs and physical examinations to assure subluxation and are treated by programs that maxi- patient compliance and reduction maintenance. After mize motion. The minority of stable palmar lip frac- 3 weeks, allowed extension is increased weekly in tures permit PIP joint hyperextension, which, if un- 10 ~ increments and reduction is confirmed radio- corrected, may lead to a swan neck deformity. To graphically. Splinting is discontinued when full ex- promote palmar plate healing, hyperextensible pal- tension is achieved, usually 6 to 8 weeks after injury. mar lip fractures can be treated with an extension block splint. A figure-of-8 splint 53 can be fabricated Unstable Palmar Lip Fractures to prevent terminal extension but allow full flexion. The primary treatment goal for unstable palmar lip Alternatively, the double aluminafoam splint method fractures is to obtain and maintain reduction so that of Strong 5~ can be used to maintain 20 ~ of PIP joint PIP joint flexion is accomplished by the normal flexion for 3 weeks and then adjusted to 10 ~ of middle phalangeal glide around the proximal phalan- additional extension over the next 2 weeks. geal head and not by hinging at the fracture edge. Nonhyperextensible stable palmar lip fractures are Accomplishing this goal requires reconstructing the best treated with early motion protected by taping the stability enhancing middle phalanx palmar lip. A finger to the adjacent digit. Fracture size or displace- large, single fragment may be fixed with Kirschner ment are unimportant as long as the joint shows no pins or lag screws, but the more commonly encoun- tendency to hyperextend or subluxate. Phair et al., 54 tered small, comminuted, and impacted fragments conducting a study of 74 stable palmar lip fractures require either traction, dynamic external fixation, or treated with a variety of techniques, reported frag- palmar plate arthroplasty. Traction or dynamic ex- ment displacement in 68% and eventual nonunion in ternal fixation are appropriate for unstable PIP joint 30%, but noted that excessive immobilization was fracture dislocations only when the joint reduces the only factor leading to an unacceptable outcome. congruently and the fracture fragments align, restor- Splint immobilization for stable palmar lip fractures ing middle phalangeal geometry. is not recommended because it can lead to stiffness Palmar plate arthroplasty is our preferred form of and persistent flexion contractures. treatment for unstable PIP fracture dislocations. This procedure reconstructs the middle phalanx palmar Tenuous Palmar Lip Fractures buttress and restores palmar plate continuity in a Tenuous palmar lip fracture dislocations involve single procedure. Postoperative redislocation is 30% to 50% of the palmar articular surface of the avoided by assuring that the palmar plate is thor- proximal phalanx and concentrically reduce with less oughly buttressed. The palmar plate, which has been than 30 ~ of flexion. Treatment must maintain joint advanced to the articular base of the middle phalanx, reduction until palmar fragment consolidation re- may not entirely fill the fracture void. In such cases, The Journal of Hand Surgery / Vol. 23A No. 3 May 1998 377

any gap between the palmar plate and middle pha- Treatment of Dorsal Lip Fractures langeal cortex is filled with fragments of excised bone, cancellous bone graft, or a superficialis tendon Successful treatment of PIP joint dorsal lip frac- slip. With increasing frequency, we are abandoning ture dislocations requires accomplishing all of the K-wire fixation and using a dynamic external fix- goals stated for palmar lip fractures in addition to ator 53 to keep the middle phalanx reduced while re-establishing central tendon continuity. At least 1 collateral ligament must rupture for dorsal lip frac- allowing immediate active and passive motion. tures to be associated with middle phalangeal palmar subluxation. 59 The continuity of the collateral liga- Treatment of Chronic Dorsal Fracture ments are evaluated by performing a lateral stress Dislocations test. Lateral instability of greater than 20 ~ indicates complete collateral ligament disruption 6~ and exten- Chronic dorsal dislocation of the PIP joint allows sive soft tissue damage that must be considered when the proximal phalanx head to sink into the middle designing treatment strategies. 6~ phalangeal fracture site. Limited flexion occurs by hinging as opposed to gliding, and articular erosion Stable Fractures develops at the contact point. When determining whether reduction is practical, the surgeon should Stable fractures do not palmarly subluxate, and the assess the condition of the intact articular cartilage primary treatment objective is to re-establish central by inspecting the lateral radiograph. Irregularities or tendon continuity. Most stable fractures are mini- erosions in the nonarticulated surfaces suggest a poor mally comminuted and range in size from a small prognosis and arthrodesis or arthroplasty should be fleck to a large fragment. Like mallet fractures, mod- considered. Joint reduction often is possible, even in erately separated lip fragments proceed to osseous or longstanding, chronic dislocations. Reduction brings stable fibrous union. There is debate as to the amount the undamaged surfaces into contact and allows a of fragment separation that compromises central ten- useful flexion arc. don function. Isani 43 suggested that restoration of Obtaining and maintaining reduction in longstand- central slip function required anatomic reduction, but ing subluxations is difficult. Donaldson and Mil- we have achieved acceptable results by accepting up lender 36 stressed the importance of surgically releas- to 2 mm separation. ing all extensor adhesion and clearing scar tissue Stable dorsal lip fractures with -<2 mm of frag- from the proximal phalangeal retrocondylar recess. ment displacement should be immobilized in full PIP Theys investigators restored stability by temporarily joint extension for 4 weeks with a splint or transar- pinning the joint in 90 ~ of flexion while the palmar ticular K-wire; the distal interphalangeal joint should structures consolidate. Patel and Joshi 42 applied an not be immobilized, and hourly active and passive external fixator to gradually stretch contracted tissues terminal phalangeal joint motion should be encour- followed by joint flexion to obtain reduction and aged. At 4 weeks, the PIP joint should be placed in encourage palmar structure contraction. a dynamic extension splint that allows active flexion, Several surgeons recommend a soft tissue restraint and at 6 weeks, passive flexion and strengthening should be instituted. to PIP joint dorsal translation with 155,56 or both 57 Fragments with greater than 2 mm of displacement flexor digitorum superficialis tendon slips or a pal- lead to an excessive extensor deficit and warrant maris longus tendon graft, 58 but predictably, re-es- open reduction and internal fixation. Whenever pos- tablishing stability requires restoration of the cup- sible, stable fixation that allows immediate postop- shaped geometry of the middle phalanx by corrective erative motion is achieved by using lag screws, 2~ osteotomy or palmar plate arthroplasty. 4~ We pre- pins coupled with a tension band wire, ~9 a pull-out fer palmar plate arthroplasty because it resurfaces the suture, or 2 K-wires. palmar surface of the middle phalanx, tightens the palmar plate, and restores the middle phalanx palmar Unstable Fractures buttress in a single procedure. Since extensor tenol- ysis and dorsal PIP capsulotomy require mobilization The goals of joint reduction, stability restoration, in the immediate postoperative period, use of a dy- and central tendon repair are accomplished by open namic external fixator should be considered to main- reduction and internal fixation of large, noncommi- tain reduction and allow early postoperative motion. nuted dorsal fragments, but highly comminuted and 378 Kiefhaber and Stern / PIP Joint Fracture Dislocations impacted fractures present difficult technical chal- untreated, portends unacceptable angulation. A sec- lenges. If the overall cup-shaped geometry of the ond indication for limited open reduction and inter- dorsal lip is restored when the joint is reduced, the nal fixation is failure of the fracture fragments of the PIP joint is pinned in full extension, thus allowing middle phalanx to assume a stable cup-shaped posi- the dorsal fragments and the central tendon insertion tion. The method of fixation chosen by the surgeon to consolidate. Dorsal lip surgical reconstruction be- should allow immediate mobilization. Traction is comes necessary when the middle phalanx cup- discontinued at 6 weeks and an aggressive range of shaped geometry is not restored following joint re- motion program is maintained. These treatment duction. Fragment elevation and bone grafting ~9 or guidelines usually result in an acceptable motion arc, central tendon suturing into the fracture bed z8 are minimal pain, and long-term remodeling. options, but significant postoperative stiffness fre- Successful treatment of PIP fracture dislocations is quently complicates both methods. The tendon ad- dependent on adherence to basic treatment princi- hesions and joint contractions may be limited by ples. It is of paramount importance that treatment applying a hinged fixator to neutralize palmar trans- re-establish the normal flexion glide of the middle location forces and allow early motion, s'44 In a novel phalanx around the proximal phalanx head. Accom- departure from the routine treatment protocol, Mor- plishing this goal requires obtaining joint reduction gan et al. j6 treated 2 palmar fracture dislocations and re-establishing stability by reconstructing the with traction and immediate motion without protect- middle phalanx cup-shaped geometry. Finally, early ing the central tendon. Both patients had excellent motion is more important than anatomic joint surface results and less than 5 ~ of extensor lag. This method reduction in obtaining acceptable clinical outcome. may provide an acceptable treatment alternative when the dorsal lip fragment moves with the middle References phalanx and separates less than 2 ram. 1. Akagi T, Hashizume H, Inoue H, Ogura T, Nagayarna N. Computer simulation analysis of fracture dislocation of the Treatment of Pilon Fractures proximal interphalangeal joint using the finite element method. Acta Med Okayama 1994;48:263-270. Good results can be obtained when all 3 PIP joint 2. Stem P J, Roman R J, Kiefhaber TR, McDonough JJ. Pilon fracture dislocation treatment principles are applied fractures of the proximal interphalangeal joint. J Hand to pilon fractures. Foremost, the normal middle pha- Surg 1991;16A:844-850. langeal glide around the proximal phalangeal head 3. Hamer DW, Quinton DN. Dorsal fracture subluxation of the proximal interphalangeal joints treated by extension must be restored. Accomplishing this requires re- block splintage. J Hand Surg 1992;17B:586-590. establishment of proximal and middle phalanx colin- 4. Inanami H, Ninomiya S, Okutsu I, Tarui T. Dynamic earity. Stability of the PIP joint is restored by frag- external finger fixator for fracture dislocation of the prox- ment realignment that reapproximates the middle imal interphalangeal joint. J Hand Surg 1993;18A: 160- phalanx cup-shaped geometry, including the all-im- 164. portant palmar buttress. Immediate motion compen- 5. Krakauer JD, Stern PJ. Hinged device for fractures involving the proximal interphalangeal joint. Clin Orthop 1996; sates for less than anatomic joint surface reduction. 327:29-37. Stern et al., 2 Morgan et al., 16 and Schenck32 have 6. McElfresh EC, Dobyns JH, O'Brien ET. Management of clinically demonstrated the efficacy of traction in fracture-dislocation of the proximal interphalangeal joints accomplishing these goals. by extension-block splinting. J Bone Joint Surg 1972;54A: The surgeon should place pilon fractures in trac- 1705-1711. tion and begin active or passive motion, as soon as 7. Dobyns JH, McElfresh EC. Extension block splinting. Hand Clin 1994; 10:229-237. possible. The traction method chosen is not as im- 8. Viegas SF. Extension block pinning for proximal interpha- portant as the surgeon's experience with the device langeal joint fracture dislocations: preliminary report of a and adherence to postoperative management details. new technique. J Hand Surg 1992;17A:896-901. The biplanar radiographs in traction should be care- 9. Inoue G, Tamura Y. Treatment of fracture-dislocation of fully assessed to determine proximal and middle the proximal interphalangeal joint using extension-block phalanx colinearity, angulation in the frontal plane, Kirschner wire. Ann Chir Main Memb Super 1991;10: 564 -568. and overall fragment alignment. Occasionally, it may 10. Twyman RS, David HG. The doorstop procedure. A tech- be necessary to perform percutaneous pinning or nique for treating unstable fracture dislocations of the limited open reduction and internal fixation to ele- proximal interphalangeal joint. J Hand Surg 1993;18B: vate asymmetric fragment depression, which, if left 714-715. The Journal of Hand Surgery / Vol. 23A No. 3 May 1998 379

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