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The central slip attachment fracture
THE CENTRAL
SLIP ATTACHMENT
FRACTURE
J. IMATAMI, H. HASHIZUME, H. WAKE, Y. MORITO and H. INOUE
From the Department of Orthopaedic Surgery, Okayama Saiseikai GeneralHospital and Okayama University Medical School, Okayama, Japan Eight displaced central slip attachment fractures were treated by open reduction and internal fixation to avoid boutonniere deformity, to reduce the fracture anatomically and to allow early mobilization of the joint. This injury should be recognized as a ~sruption of the dynamic extensor mechanism associated with an intraarticular fracture, fracture-dislocation or soft tissue injury of the PIP joint. We have grouped central slip attachment fractures into three types according to the mechanism of injury, with suggested methods of treatment.
Journal of Hand Surgery (British and European Volume, 1997) 22B: 1." 107-109 The central slip attachment fracture (CAF) has been recognized in association with a palmar (anterior) fracture-dislocation of the PIP joint (Spinner and Choi, 1970). But a traction force on the attachment of the central slip of the middle phalanx can also produce CAF without dislocation of the PIP joint. The fracture area is the attachment of the central slip which acts as the dynamic extensor mechanism. This fracture may be associated with an intraarticular fracture or fracturedislocation, or soft tissue injuries of the PIP joint. It reduces the effectiveness of the central slip mechanism and includes the so-called dorsal plate injury of the PIP joint (Slattery, 1990). The serious and disabling soft tissue injuries associated with this injury are not commonly recognized, thereby resulting in casual or inadequate treatment. The paucity of reports has resulted in few guidelines for treatment in such cases. This study reviews the classification of CAF according to the mechanism of injury, and the most appropriate methods of treatment.
Classification and operative procedure
Using clinical and X-ray findings, and mechanism of injury, we classified CAF into three types: type 1 (avulsion), type 2 (split), type 3 (split-depression) (Fig 1). Type 1 is an avulsion of the attachment of the central slip of the middle phalanx (Fig 2). In these cases, two or three K-wires were used for internal fixation (Fig 3). Type 2 is a split which has a longitudinal triangularlyshaped fragment attached to the central slip, without any depression of the articular surface. This fragment is fixed by one or two K-wires. Type 3 has a split depressed fracture which requires open reduction, bone graft from the radial styloid and internal fixation with two or three K-wires. RESULTS
The joints of all patients were stable and pain free through their range of active motion after treatment. The minimum arc of PIP joint movement was 55 ° and the maximum 70 ° (Table 1). None of the patients regained their pre-injury joint motion, and none have sought further care for complaints of discomfort, muscle weakness or deformity.
PATIENTS A N D M E T H O D S
X-rays of eight patients who sustained a closed CAF of the little finger which required surgery between 1985 to 1995 were reviewed. The patients' ages ranged from 16 to 77 with an average of 39 years. All patients were seen within 13 days of injury. Six patients were male and two were female. Three injured the dominant hand. The patients were followed for 4 to 12 months from the start of treatment with an average follow-up of 6 months (Table 1).
DISCUSSION Very little is to be found in the literature regarding this uncommon injury (Spinner and Choi, 1970; Peimer et al, 1984; Hastings and Carroll, 1988). A force great enough to produce a palmar dislocation can cause a
Table 1--Central slip attachment fractures
Case 1 2 3 4 5 6 7 8
Age(years)/sex 55/M 19/M 39/M 29/M 77/F 45/M 33/F 16/M
Hand/digit L(ND)/little L(ND)/little R(D)/little R(D)/little L(ND)/little R (D)/little R(D)/little R ( D)/little
Mechanism of injury
Type of"lesion
Fall Sports Sports Fall Fall Fall Fall Sports
1 2 3 3 3 3 1 3
107
PostoperativePIP motion
Follow-up(months)
10-80 ° 15-70 ° 15-70 ° 10 65 ° 10-80 ° 15-75 ° 10 80 ° 0-70 °
6 12 4 4 6 4 5 9
108
T H E J O U R N A L OF H A N D SURGERY VOL. 22B No. 1 FEBRUARY 1997
Fig 2
Intraoperative photograph showing a central slip attachment fracture.
Fig 3
Lateral X-ray: (a) preoperative (b) postoperative.
Fig 1 Classification and clinical appearence of central slip attachment fractures: (a) type 1 (avulsion), (b) type 2 (split), (c) type 3 (split depression). C A F or disrupt the central slip. But a lesser traction force to the attachment of the central slip of the middle phalanx can produce C A F without dislocation of the PIP joint. The fracture site is the attachment of the central slip which acts as the dynamic extensor mechanism, and this lesion m a y be associated with an intraarticular fracture or dislocation, or soft tissue injuries of the PIP joint, especially the dorsal plate. Restoration of function to the dorsal plate stabilizes the PIP joint and the extensor tendon and increases the moment arm of the extensor tendon (Slattery, 1990). A type 1 injury is apparently caused by a combination of an anteriorly directed force which displaces the base of the middle phalanx forward on its dorsal part and a
109
CENTRAL SLIP ATTACHMENT FRACTURE
traction force on the central slip of the extensor mechanism. Type 2 is caused by an initial force applied to the PIP joint from a distal and dorsal direction with two effects: longitudinal shearing force and forward displacement of the base of the middle phalanx. If these forces combine with a lateral force on the base of the middle phalanx, the PIP joint dislocates laterally. Finally, axial loads can compress and shear the articular surface of the PIP joint (type 3). The central articular surface is depressed, and the dorsal articular rim with the central slip separates suddenly. Near the neutral position, axial forces cause split-depression fractures and impacted forces in the completely neutral position may produce pilon type fractures of the base of the middle phalanx (Stern et al, 1991). If these forces combine with a lateral force on the base of the middle phalanx, the PIP joint dislocates palmarly. The extent of the damage and the type of injury may be determined largely by the amount, direction and location of forces, the flexion angle of the PIP joint and the tension in the intrinsic ligaments and extrinsic muscles (Akagi et al, 1994; Hashizume et al, 1991). The undisplaced CAF is best managed conservatively. It is our belief that prompt reduction and internal fixation of the displaced fracture to avoid a boutonnibre deformity and retain the functions of the dynamic extensor mechanism can also be expected to produce
satisfactory results. In the displaced split type, open reduction and internal fixation is recommended to allow immediate active range of motion. Finally, the displaced split-depression type should be openly reduced, bone grafted, and internally fixed to reduce the articular surface of the middle phalangeal base anatomically and mobilize the joint at an early stage. References
,:
AKAGI T, HASHIZUME H, INOUE H, OGURA T and NAGAYAMA N ( t 991 ). Computer simulation analysis of fracture dislocation of the proximal interphalangeal joint using the finite element method. Acta Medica Okayama, 48:263 270. HASHIZUME H, NAGASAWA F, WAKE H, HARA S and AKAHORI O (t991). Study of middle phalangeal base fracture. Journal of the Japanese Society for Surgery of Hand, 8: 709-713. HASTINGS H and CARROLL C (1988). Treatment of closed articular fractures of the metacarpopfialangeal and proximal interphalangeal joints. Hand Clinics, 4: 503-527. PEIMER C A, SULLIVAN D J and WILD D R (1984). Palrnar dislocation of the proximal interphalangeal joint. Journal of Hand Surgery, 9A: 39-48. SLATTERY P G (1990). The dorsal plate of the proximal interphalangeal joint. Journal of Hand Surgery, 15B: 68-73. SPINNER M and CHOI B Y (1970). Anterior dislocation of the proximal interphalangeal joint. Journal of Bone and Joint Surgery, 52A: 1329-1336. STERN P J, ROMAN R J, KIEEHABER T J and McDONOUGH J J (1991). Pilon fractures of the proximal interphalangeal joint. Journal of Hand Surgery, 16A: 844-850.
Received: 18 April 1996 Accepted after revision: 7 June 1996 Dr H. Hashizume, Department of Orthopaedic Surgery, Okayama, UniversityMedical School 2-5-1 Shikata-cho, Okayama, Japan 700. © 1997 The British Societyfor Surgery of the Hand
SLIP ATTACHMENT
FRACTURE
J. IMATAMI, H. HASHIZUME, H. WAKE, Y. MORITO and H. INOUE
From the Department of Orthopaedic Surgery, Okayama Saiseikai GeneralHospital and Okayama University Medical School, Okayama, Japan Eight displaced central slip attachment fractures were treated by open reduction and internal fixation to avoid boutonniere deformity, to reduce the fracture anatomically and to allow early mobilization of the joint. This injury should be recognized as a ~sruption of the dynamic extensor mechanism associated with an intraarticular fracture, fracture-dislocation or soft tissue injury of the PIP joint. We have grouped central slip attachment fractures into three types according to the mechanism of injury, with suggested methods of treatment.
Journal of Hand Surgery (British and European Volume, 1997) 22B: 1." 107-109 The central slip attachment fracture (CAF) has been recognized in association with a palmar (anterior) fracture-dislocation of the PIP joint (Spinner and Choi, 1970). But a traction force on the attachment of the central slip of the middle phalanx can also produce CAF without dislocation of the PIP joint. The fracture area is the attachment of the central slip which acts as the dynamic extensor mechanism. This fracture may be associated with an intraarticular fracture or fracturedislocation, or soft tissue injuries of the PIP joint. It reduces the effectiveness of the central slip mechanism and includes the so-called dorsal plate injury of the PIP joint (Slattery, 1990). The serious and disabling soft tissue injuries associated with this injury are not commonly recognized, thereby resulting in casual or inadequate treatment. The paucity of reports has resulted in few guidelines for treatment in such cases. This study reviews the classification of CAF according to the mechanism of injury, and the most appropriate methods of treatment.
Classification and operative procedure
Using clinical and X-ray findings, and mechanism of injury, we classified CAF into three types: type 1 (avulsion), type 2 (split), type 3 (split-depression) (Fig 1). Type 1 is an avulsion of the attachment of the central slip of the middle phalanx (Fig 2). In these cases, two or three K-wires were used for internal fixation (Fig 3). Type 2 is a split which has a longitudinal triangularlyshaped fragment attached to the central slip, without any depression of the articular surface. This fragment is fixed by one or two K-wires. Type 3 has a split depressed fracture which requires open reduction, bone graft from the radial styloid and internal fixation with two or three K-wires. RESULTS
The joints of all patients were stable and pain free through their range of active motion after treatment. The minimum arc of PIP joint movement was 55 ° and the maximum 70 ° (Table 1). None of the patients regained their pre-injury joint motion, and none have sought further care for complaints of discomfort, muscle weakness or deformity.
PATIENTS A N D M E T H O D S
X-rays of eight patients who sustained a closed CAF of the little finger which required surgery between 1985 to 1995 were reviewed. The patients' ages ranged from 16 to 77 with an average of 39 years. All patients were seen within 13 days of injury. Six patients were male and two were female. Three injured the dominant hand. The patients were followed for 4 to 12 months from the start of treatment with an average follow-up of 6 months (Table 1).
DISCUSSION Very little is to be found in the literature regarding this uncommon injury (Spinner and Choi, 1970; Peimer et al, 1984; Hastings and Carroll, 1988). A force great enough to produce a palmar dislocation can cause a
Table 1--Central slip attachment fractures
Case 1 2 3 4 5 6 7 8
Age(years)/sex 55/M 19/M 39/M 29/M 77/F 45/M 33/F 16/M
Hand/digit L(ND)/little L(ND)/little R(D)/little R(D)/little L(ND)/little R (D)/little R(D)/little R ( D)/little
Mechanism of injury
Type of"lesion
Fall Sports Sports Fall Fall Fall Fall Sports
1 2 3 3 3 3 1 3
107
PostoperativePIP motion
Follow-up(months)
10-80 ° 15-70 ° 15-70 ° 10 65 ° 10-80 ° 15-75 ° 10 80 ° 0-70 °
6 12 4 4 6 4 5 9
108
T H E J O U R N A L OF H A N D SURGERY VOL. 22B No. 1 FEBRUARY 1997
Fig 2
Intraoperative photograph showing a central slip attachment fracture.
Fig 3
Lateral X-ray: (a) preoperative (b) postoperative.
Fig 1 Classification and clinical appearence of central slip attachment fractures: (a) type 1 (avulsion), (b) type 2 (split), (c) type 3 (split depression). C A F or disrupt the central slip. But a lesser traction force to the attachment of the central slip of the middle phalanx can produce C A F without dislocation of the PIP joint. The fracture site is the attachment of the central slip which acts as the dynamic extensor mechanism, and this lesion m a y be associated with an intraarticular fracture or dislocation, or soft tissue injuries of the PIP joint, especially the dorsal plate. Restoration of function to the dorsal plate stabilizes the PIP joint and the extensor tendon and increases the moment arm of the extensor tendon (Slattery, 1990). A type 1 injury is apparently caused by a combination of an anteriorly directed force which displaces the base of the middle phalanx forward on its dorsal part and a
109
CENTRAL SLIP ATTACHMENT FRACTURE
traction force on the central slip of the extensor mechanism. Type 2 is caused by an initial force applied to the PIP joint from a distal and dorsal direction with two effects: longitudinal shearing force and forward displacement of the base of the middle phalanx. If these forces combine with a lateral force on the base of the middle phalanx, the PIP joint dislocates laterally. Finally, axial loads can compress and shear the articular surface of the PIP joint (type 3). The central articular surface is depressed, and the dorsal articular rim with the central slip separates suddenly. Near the neutral position, axial forces cause split-depression fractures and impacted forces in the completely neutral position may produce pilon type fractures of the base of the middle phalanx (Stern et al, 1991). If these forces combine with a lateral force on the base of the middle phalanx, the PIP joint dislocates palmarly. The extent of the damage and the type of injury may be determined largely by the amount, direction and location of forces, the flexion angle of the PIP joint and the tension in the intrinsic ligaments and extrinsic muscles (Akagi et al, 1994; Hashizume et al, 1991). The undisplaced CAF is best managed conservatively. It is our belief that prompt reduction and internal fixation of the displaced fracture to avoid a boutonnibre deformity and retain the functions of the dynamic extensor mechanism can also be expected to produce
satisfactory results. In the displaced split type, open reduction and internal fixation is recommended to allow immediate active range of motion. Finally, the displaced split-depression type should be openly reduced, bone grafted, and internally fixed to reduce the articular surface of the middle phalangeal base anatomically and mobilize the joint at an early stage. References
,:
AKAGI T, HASHIZUME H, INOUE H, OGURA T and NAGAYAMA N ( t 991 ). Computer simulation analysis of fracture dislocation of the proximal interphalangeal joint using the finite element method. Acta Medica Okayama, 48:263 270. HASHIZUME H, NAGASAWA F, WAKE H, HARA S and AKAHORI O (t991). Study of middle phalangeal base fracture. Journal of the Japanese Society for Surgery of Hand, 8: 709-713. HASTINGS H and CARROLL C (1988). Treatment of closed articular fractures of the metacarpopfialangeal and proximal interphalangeal joints. Hand Clinics, 4: 503-527. PEIMER C A, SULLIVAN D J and WILD D R (1984). Palrnar dislocation of the proximal interphalangeal joint. Journal of Hand Surgery, 9A: 39-48. SLATTERY P G (1990). The dorsal plate of the proximal interphalangeal joint. Journal of Hand Surgery, 15B: 68-73. SPINNER M and CHOI B Y (1970). Anterior dislocation of the proximal interphalangeal joint. Journal of Bone and Joint Surgery, 52A: 1329-1336. STERN P J, ROMAN R J, KIEEHABER T J and McDONOUGH J J (1991). Pilon fractures of the proximal interphalangeal joint. Journal of Hand Surgery, 16A: 844-850.
Received: 18 April 1996 Accepted after revision: 7 June 1996 Dr H. Hashizume, Department of Orthopaedic Surgery, Okayama, UniversityMedical School 2-5-1 Shikata-cho, Okayama, Japan 700. © 1997 The British Societyfor Surgery of the Hand