Grey Giddins
DEFINITION
Proximal interphalangeal (PIP) joint bone injuries may affect the convex side of the joint (end of the proximal phalanx) or the concave side of the joint (base of the middle phalanx).
Convex-side injuries are typically simple (two-fragment) injuries best treated with open reduction and internal fixation if surgery is required.
Concave-side injuries tend to be comminuted (multifragmented), presenting either as fracture-subluxations or dislocations or a pilon fracture.
Fracture subluxations-dislocations typically involve dorsal displacement of the main (dorsal) fragment of the middle phalanx (FIG 1A), although volar and lateral subluxations and dislocations are less common (FIG 1B,C).
Dorsal fracture-dislocations typically occur after a hyperextension injury of the PIP joint.
Pilon fractures are compression fractures of the base of the middle phalanx (rarely the distal phalanx) and are characterized by depression of the central articular component and splaying of the articular margins.
This may be associated with longitudinal fracture extension that may reach most of the length of the middle phalanx.
There is typically marked comminution of the base of the middle phalanx (FIG 1D,E).
The fracture typically occurs due to a longitudinal (end-on) force, crushing the base of the middle phalanx (rarely the distal phalanx or thumb proximal phalanx). This may occur due to a fall or miscatching a ball (eg, at cricket or baseball).
ANATOMY
The distal end of the proximal phalanx is a convex surface made up of two condyles. The proximal end of the middle phalanx is a concave surface (FIG 2A).
FIG 1 • A. A typical (more severe) dorsal fracture-dislocation with involvement of about 65% of the volar articular surface. B,C. Proximal interphalangeal joint volar dislocation. D,E. Proximal interphalangeal joint pilon fracture.
FIG 2 • A. The distal end of the proximal phalanx is a convex surface made up of two condyles. The proximal end of the middle phalanx is a concave surface. The two are linked by ligaments. B. The strongest is the volar plate and the volar part of the lateral collateral ligaments. These resist dorsal subluxation of the proximal interphalangeal joint when loaded.
The two bones are linked and stabilized by ligaments (FIG 2B).
These structures resist dorsal subluxation of the PIP joint when loaded:
Volar plate
Collateral ligaments (radial and ulnar)
PATHOGENESIS
The tendon attachments are dorsal proximal and weak through the central slip and volar distal and strong through the flexor digitorum superficialis tendon slips. Thus, the flexor forces dominate the extensor forces.
The shape of the joint and the soft tissue restraints allow a powerful lever arm to work for flexion. If, however, the volar restraint fails (particularly in a dorsal fracture-dislocation), the resultant forces lead to dorsal subluxation and proximal migration of the main dorsal fracture fragment of the middle phalanx (FIG 3A).
Research work and clinical experience have shown that the joint will be stable if up to 42% of the volar half of the middle phalanx articular surface is damaged as measured on a lateral radiograph (FIG 3B).
In practice, subluxation can occur with as little as 10% to 15% of joint surface loss, but that is uncommon.
For pilon fractures, the condyles of the proximal phalanx are driven up into the base of the middle phalanx, displacing the central part of the articular surface distally and splaying the dorsal-volar and lateral margins of the middle phalanx joint surface. This injury is longitudinally unstable and results in proximal migration and diminution or obliteration of the joint space, usually with significant articular incongruity.
PATIENT HISTORY AND PHYSICAL FINDINGS
Most patients present within a few days, although later presenters (up to 2 to 3 weeks) are common and some very late presenters (after 6 weeks) are also seen.
The delays are usually due to underestimation of the severity of the injury either by the patient (who thinks he or she has a sprain and it will resolve) or medical/paramedical staff (who fail to perform or interpret properly an adequate radiograph).
The finger will be swollen and tender, centered around the PIP joint.
An angular deformity may be evident.
Subluxation of the joint may be clinically evident, visually or by palpation.
There will be reduced range of movement throughout the finger and particularly in the PIP joint.
Fracture-Dislocation Involving the Proximal Interphalangeal Joint
Most are mild injuries with limited volar plate avulsion that reduce either spontaneously or with assistance, usually under local anesthesia (FIG 4A–D). Radiographs may reveal a small volar bone avulsion from the base of the middle phalanx. These injuries are longitudinally stable.
The examiner must test for stability through a full arc of motion.
If there is a tendency for subluxation, the position of the joint that allows this instability is recorded.
More severe injuries (ie, involving a greater part of the volar lip) may be longitudinally unstable, resulting in persistent subluxation of the PIP joint with attendant clinical findings as described above.
FIG 3 • A. Diagram of fracture-dislocation. B. Diagram showing volar loss, which may lead to instability.
FIG 4 • A. Dorsal lateral fracturedislocation with a small avulsion fragment before (A,B) and after (C,D) reduction. E. Dorsal fracture-subluxation with joint incongruity and a classic V-sign (see HA-36 FIG 4B).
Subluxation and dislocation are best visualized on the lateral radiograph and may be quite subtle, appearing as joint incongruity at the dorsum of the joint (the triangle sign, due to dorsal overhang of the base of the middle phalanx) (FIG 4E).
IMAGING AND OTHER DIAGNOSTIC STUDIES
The key investigation is plain radiology.
Often only radiographs of the hand are taken in the emergency department. These are not adequate. Posteroanterior and lateral radiographs need to be taken, centered on the PIP joint of the injured finger (FIG 5).
The key information obtained from the radiographs (supplemented by physical examination) can be used to differentiate stable from unstable injuries, either of fracture-subluxations or dislocations or pilon fractures.
Fluoroscopy can be of great value in assessing the injury and joint stability.
DIFFERENTIAL DIAGNOSIS
Soft tissue
Volar plate injury
Collateral ligament injury
Central slip injury
Bone
Proximal phalanx condylar injury
Proximal phalanx distal diaphyseal injury
Middle phalanx proximal diaphyseal injury
NONOPERATIVE MANAGEMENT
If the injury is stable, early protected mobilization can start within 1 week of injury.
Fracture-Dislocation
A stable injury (the majority of cases) can be treated with early mobilization concentrating on regaining extension, which is commonly lost.
Only if there is significant pre-existing volar plate laxity (often occurs in young women) is there a need for an extension block splint for up to 6 weeks.
Most patients regain full or nearly full movement but may be left with minor swelling and stiffness and mild cold discomfort.
Heavy activity may cause discomfort.
In approximately 5% of patients the joint remains significantly swollen and uncomfortable beyond 6 weeks. This is probably due to persistent joint synovitis, which usually resolves with a steroid injection.
If the joint is unstable but there is limited volar joint damage (less than about 30 degrees), it may reduce when held in flexion with a dorsal block splint.
FIG 5 • Hand radiographs are interpretable only with a true lateral radiograph of the proximal interphalangeal joint.
Joint reduction and congruity must be documented radiologically and should not require more than about 50 degrees of joint flexion, or unacceptable PIP joint stiffness may result.
Patients should be encouraged to flex and extend to the splint. They should be seen weekly for 4 weeks. Flexion of the splint is reduced by about 10 degrees each week. At each increase in extension, the reduction needs to be precisely checked radiologically.
A reasonable range of movement with only a mild flexion contracture and loss of flexion is anticipated.
Pilon Fractures
The minority of pilon fractures have minimal displacement (less than 1 mm) and a reasonable joint space (FIG 6). These are usually stable injuries but must be carefully assessed clinically.
Most of these patients can achieve a range of movement from 10 to 20 degrees short of full extension to 70 to 80 degrees of flexion with only mild discomfort.
Patients can start early gentle mobilization with part-time protection in a splint at night and outdoors for 4 weeks.
Patients treated with early, protected mobilization need clinical and radiologic review weekly for at least 2 to 3 weeks.
Most patients will achieve a nearly full range of motion with minimal pain, stiffness, or swelling.
If there is greater displacement, then surgery is almost always needed to achieve longitudinal stability and early movement.
SURGICAL MANAGEMENT
Preoperative Planning
The proximal wire is always placed at or near the center of rotation of the injured joint.
Distal wire placement needs to be planned.
For fractures localized to the base of the middle phalanx, the distal wire can be anywhere from the midpart of the middle phalanx or more distal. In fact, the middle phalanx is narrowest at this point, so the wire is more easily placed distally.
FIG 6 • Pilon fracture that was sufficiently congruent and comfortable to respond to early mobilization with a good longterm result. This could not have been predicted radiologically, and all cases require clinical assessment.
If the fracture extends distally, as can easily occur with pilon fractures, the distal wire should be distal to that extension to ensure adequate fixation and stability. The distal wire can be placed as far distal as the head of the middle phalanx.
I have never had a fracture so distal that the distal wire could not gain adequate fixation.
The procedure is best performed under local anesthesia. This allows the patient to participate during the operation. The patients also understands what has happened and is often clearer about the postoperative regimen.
At least 10 mL of plain 0.5% bupivacaine is injected at the midmetacarpal level. Bupivacaine works more slowly than lidocaine, but if given before skin preparation, it usually works completely by the time surgery starts. It then provides prolonged anesthesia for 12 to 36 hours. This helps reduce postoperative pain.
Positioning
Informed consent is needed, with a discussion of the risks and benefits of the various conservative (nonoperative) and surgical options.
Risks include infection, nerve injury, stiffness, scar tenderness, nonunion, malunion, the need for revision procedures, and the risk associated with any operation (ie, making the patient worse).
The digit needs to be marked very clearly, especially if the patient is receiving general anesthesia (the minority of patients).
Typically 1.5 g of cefuroxime is administered preoperatively. There is no need for postoperative antibiotics.
The patient lies supine with the affected hand out on an armboard at 90 degrees to the table (ie, standard position for hand surgery).
A proximal arm tourniquet is applied as a backup to the digital tourniquet.
The skin is prepared with chlorhexidine in an alcohol solution with a pink dye to ensure that all the fingers have been fully painted. If the finger has had adhesive dressings on it or has not been well cleaned, the anesthetized finger is scrubbed before skin preparation.
The operated arm is draped sterilely.
Approach
The operation is performed closed with insertion of percutaneous wires.
TECHNIQUES
INSERTING THE WIRES
I use 1.1-mm K-wires: 0.9-mm wires are too flexible and 1.6-mm wires are too rigid. I know that 1.2-mm wires have been used successfully. I suspect that wires from 1.0 to 1.3 mm are fine, but I recommend 1.1-mm wires.
Identify the level of the center of rotation of the PIP joint with the image intensifier and mark this level on the skin (TECH FIG 1A,B).
Insert the wire partially through the proximal phalanx and check carefully on the image intensifier with true posteroanterior and lateral projections (TECH FIG 1C).
Aim 1 to 2 mm proximal rather than distal to remain extracapsular (the capsule of the joint reflects proximally). A distal wire may risk a joint infection if pin track sepsis develops.
TECH FIG 1 • A,B. Checking the position for the first wire at the level of the center of rotation of the proximal interphalangeal joint with the image intensifier and marking it on the skin. C. Wire inserted across the head of the proximal phalanx and confirmed on the image intensifier before advancing further. (continued)
TECH FIG 1 • (continued) D,E. Finding and marking the position of the distal wire as for the proximal wire. This placement is more distal in the head of the middle phalanx than average because the distal interphalangeal joint was also injured. F,G. Inserting the distal wire and confirming its position on the image intensifier.
Placing this wire too far proximal of the construct will restrict full joint movement. This is the most important step in the whole procedure.
Identify an appropriate level in the distal half to two thirds of the middle phalanx, distal to any fracture extension in the shaft of the middle phalanx, with the image intensifier.
Mark this level on the skin.
This wire may be inserted near the center of rotation of the distal interphalangeal (DIP) joint, in the distal middle phalanx. This is acceptable because the bone is wider and provides more margin for error (TECH FIG 1D,E).
Insert the wire partially through the middle phalanx and check carefully (posteroanterior and lateral) on the image intensifier (TECH FIG 1F,G).
Aim to be perpendicular to the long axis of the finger and parallel to both the plane of rotation and the first wire (which should also be in the plane of rotation).
Insert the wire so equal lengths are present on either side of the finger (by doing this for the proximal wire, where it is less important, you will have a guide for the distal wire). This helps in the wire bending. If one end is too short it can become difficult to bend, especially in patients with long fingers.
BENDING THE WIRE
Wire bending is the more technically demanding part of the procedure. It is important to understand and follow the steps carefully.
One may create the construct in reverse of that described below, but this results in motion on the proximal wire rather than the distal wire, which in theory increases the risk of pin track and PIP joint sepsis.
To ensure enough but not too much clearance from the finger, the wire is held with a medium needle holder against the skin, then manually bent past a right angle (because there is spring in the wire).
Bend the opposite half of the wire to the same degree and in the same direction.
Bend the distal wire on each side through 90 degrees (TECH FIG 2A,B).
Bend each half of the distal wires to make the linkage between the wires (TECH FIG 2C,D).
It is critical that this bend is sufficiently distal in the wire (proximal relative to the finger) to ensure that the construct is long enough and provides adequate joint distraction.
If the bend is not distal enough, it is difficult to salvage, and you will probably need to remove the distal wire and insert a new wire.
Grip the distal wires with the medium needle holder just after the second bend and bend the distal end back up about 135 degrees, creating a Z shape (TECH FIG 2E).
The proximal wire will sit in the distal narrow angle of the Z.
It important to put the Zs at the same level, although the construct can tolerate some mismatch.
If the Zs are at different levels, careful unbending or further bending of the wires should help.
The proximal wire is flicked into place in the distal angle of the Z (TECH FIG 2F).
It should bow, showing that tension has been applied across the construct and thus traction across the joint.
Improved fracture and joint alignment can be visualized on the image intensifier.
TECH FIG 2 • A,B. Grasping the distal wire with the needle holder and making the first bend. C,D. Start and completion of the second wire bend. E. Third wire bend shown on a freestanding wire. F. The properly bent distal wire is placed around the proximal wire distracting the joint.
TIDYING UP AND ENSURING THE CONSTRUCT DOES NOT DISENGAGE
Proximal Wire
Bend the proximal wire down. Place the medium needle holder on the wire, pushing the Z construct of the distal wire against the skin (TECH FIG 3A,B).
This ensures that the construct is neither too bulky nor too close to the finger, allowing for some swelling.
A distance of about 3 to 4 mm is effective.
Bend the proximal wire down about 135 degrees (TECH FIG 3C).
Cut the proximal wire with wire cutters about 3 mm after the bend and crimp the cut ends (TECH FIG 3D,E).
If too short, it cannot be bent; if too long, it will abut the finger.
TECH FIG 3 • A,B. Grasping the proximal wire and making the first bend on the proximal wire shown on a patient. C. Bend the wire approximately 135 deegrees. D. Cut the proximal wire 3 mm after the bend. E. Crimping cut ends of proximal wires.
Distal Wire
Crimp the distal point of the wire and the part of the proximal wire just outside the skin down together with the medium needle holders (TECH FIG 4A).
Do not crimp too far or the middle phalanx wire will be gripped and not allow full rotation.
The wire has to be bent enough to ensure that the construct cannot disengage.
Bend the distal tail of each Z over to ensure that the proximal wire cannot disengage (TECH FIG 4B).
This process leaves slightly irregular cut wire ends. These need to be kept close to the construct and typically do not cause problems, but if they do they can be covered postoperatively.
Check the final fracture position on the image intensifier (TECH FIG 4C,D).
At the end of the operation, if the patient is under local anesthesia, ask him or her to watch the injured digit while extending the PIP joint to neutral and flexing to at least 90 degrees.
This method of educating the patient is painless and gives him or her greater confidence in the postoperative period.
Force Couple
Some surgeons advocate a force couple—that is, a third wire in the proximal end of the middle phalanx that hooks under the bent distal middle phalanx wire to force the middle phalanx volar and improve dorsal joint subluxation (TECH FIG 5).
We have not needed a force couple, nor is there any evidence as yet to support its use.
TECH FIG 4 • A,B. Distal wire bends completed. The fourth bend is just to prevent disengagement of the construct. C,D. The position of the final construct on a patient on whom, for the only time in my practice, I used a double fixator on one finger. The proximal interphalangeal joint had a pilon fracture, which is well but not perfectly reduced. The distal interphalangeal joint had a fracture-dislocation that is also well but not perfectly reduced.
TECH FIG 5 • Drawing of a Suzuki frame showing a third (middle) wire in position, where it can act as a force couple.
POSTOPERATIVE CARE
The construct should not disimpact if made properly. If it does, it can usually be adjusted in clinic with further wire bending. Local anesthesia may be needed.
The hand is elevated maximally for 3 to 5 days and movement is started once the patient is comfortable.
The use of a long-acting local anesthetic means the patient can go home and start taking simple oral analgesics (eg, ibuprofen and diclofenac, paracetamol and codeine, or both).
Opiate analgesics are rarely required, and almost no patient complains of significant pain.
The analgesics should continue for at least 24 hours but not longer than 1 week.
Long slow stretches both into extension and into flexion are emphasized. They should be performed hourly.
The stretches should be held for 5 minutes at a time. They should not be painful, although they need to be at least on the edge of discomfort or in the mildly uncomfortable range. Painful stretches will lead to more swelling, increase the risk of complex regional pain syndrome type I, and discourage the patient from performing exercises.
Formal therapy visits begin the second postoperative week. In addition to PIP motion, DIP motion is emphasized. The therapist works with these patients at least weekly.
The patient is checked after 5 to 7 days.
The dressing is removed and radiographs are performed to ensure that the reduction has been maintained.
The dressings are left off and the patient is instructed in pin track care (see below), care of the sharp wire points (ie, covering them with tape if necessary), and stretching exercises, supported by a hand therapist.
The pins are cleaned and dried as one would for their hand day to day.
Assuming the pin tracks stay dry, nothing more needs to be done.
If the pin tracks start oozing, clean with preboiled water four times a day.
If the pin sites do not improve within 24 hours, I advise the patient to seek medical help for antibiotics.
The redness and oozing should resolve within 2 to 3 days. If not, the patient may require intravenous antibiotics and early pin removal, but this is extremely rare.
The patient is checked again about 2 weeks postoperatively.
At this stage the finger will still be mildly swollen.
There should be minimal or no pain except with stretches.
The pin tracks should be clean and dry.
The range of movement should be in the PIP joint a fixed flexion deformity of no more than 10 degrees and flexion to at least 50 degrees, and in the DIP joint full extension and flexion to at least 50 degrees.
If this has been achieved, the patient returns to the office 4 to 5 weeks postoperatively for wire removal. There appears no good reason to leave the wires in longer, and the incidence of pin track sepsis increases after 4 weeks.
Final review takes place 10 to 12 weeks after surgery.
OUTCOMES
The finger will still be mildly swollen; this will never resolve fully.
The final range of movement will have been achieved; it should be about 10 to 90 degrees in the PIP joint and full (0 to 70 degrees) in the DIP joint. There should be no rest pain but there will probably be some achiness with heavy use. The pin tracks should have healed with minimal if any tenderness or cosmetic abnormality.
Pilon fractures typically reduce only in part, with at least one impacted fragment remaining impacted in the middle phalanx.
Because the concave side of the joint seems to tolerate some incongruity well, this fragment is not routinely disimpacted.
Fracture-dislocations also tend to reduce incompletely, with some mild residual dorsal subluxation of the joint surface (ie, widening of the joint on the lateral view). If mild, this too is well tolerated.
Traction devices generally give reliable results, with range of motion of about 89 degrees and only 2% poor results; open reduction and internal fixation gives range of motion of 79 degrees and 10% to 12% poor results.
COMPLICATIONS
Complications are uncommon but recovery is never full, as indicated above.
Pin track infection is the most common risk, but if the wires are removed between 4 and 5 weeks it is uncommon (less than 10% of cases). It typically resolves with cleaning, elevation, and 2 to 3 days of oral antibiotics (typically flucloxacillin 500 mg four times a day and amoxicillin 500 mg three times a day).
Mild malunion is accepted and well tolerated.
Nonunion has not occurred as a functional problem, although radiographs may show odd ununited peripheral fragments of bone.
Nerve injury may occur.
Significant poor results and persistent rest pain occur in only about 3% to 5% of patients.
REFERENCES
1. Agee JM. Unstable fracture dislocation of the proximal interphalangeal joint. Clin Orthop Relat Res 1987;214:101–112.
2. Aladin A, Davis TR. Dorsal fracture-dislocation of the proximal interphalangeal joint: a comparative study of percutaneous Kirschner wire fixation versus open reduction and internal fixation. J Hand Surg Br 2005;30B:120–128.
3. Allison DM. Fractures of the base of the middle phalanx treated by dynamic external fixation. J Hand Surg Br 1996;21B:305–310.
4. Badia A, Riano F, Ravikoff J, et al. Dynamic intradigital external fixation for proximal interphalangeal joint fracture dislocations. J Hand Surg Am 2005;30A:154–160.
5. Deitch M, Kiefhaber T, Rodney Comisar B, et al. Dorsal fracture dislocations of the proximal interphalangeal joint: surgical complications and long-term results. J Hand Surg Am 1999;24A:914–923.
6. Deshmukh SC, Kumar D, Mathur K, et al. Complex fracture-dislocation of the proximal interphalangeal joint of the hand: results of a modified pins and rubbers traction system. J Bone Joint Surg 2004; 86B:406–412.
7. De Smet L, Boone P. Treatment of fracture-dislocation of the proximal interphalangeal joint using the Suzuki external fixator. J Orthop Trauma 2002;16(9):668–671.
8. de Soras X, de Mourgues P, Guinard D, et al. Pins and rubbers traction system. J Hand Surg Br 1997;22B:730–735.
9. Duteille F, Pasquier P, Lim A, et al. Treatment of complex interphalangeal joint fractures with dynamic external traction: a series of 20 cases. Plast Reconstr Surg 2003;15:1623–1629.
10. Fahmy NRM. The Stockport serpentine spring system for the treatment of displaced comminuted intra-articular phalangeal fractures. J Hand Surg Br 1990;15B:303–311.
11. Grant I, Berger AC, Tham SK. Internal fixation of unstable fracture dislocations of the proximal interphalangeal joint. J Hand Surg Br 2005;30B:492–498.
12. Hamilton SC, Stern PJ, Fassler PR, et al. Mini-screw fixation for the treatment of proximal interphalangeal joint dorsal fracture-dislocations. J Hand Surg Am 2006;31A:1349–1354.
13. Hastings H, Carroll C. Treatment of closed articular fractures of the metacarpophalangeal and proximal interphalangeal joints. Hand Clin 1988;4(3):503–527.
14. Inanami H, Ninomiya S, Okutsu I, et al. Dynamic external finger fixator for fracture dislocation of the proximal interphalangeal joint. J Hand Surg Am 1993;18A:160–164.
15. Kiefhaber T, Stern PJ. Fracture-dislocations of the proximal interphalangeal joint. J Hand Surg Am 1998;23A:368–380.
16. Krakauer JD, Stern PJ. Hinged device for fractures involving the proximal interphalangeal joint. Clin Orthop Relat Res 1996;327:29–37.
17. Schenk RR. The dynamic traction method: combined movement and traction for interarticular fractures of the phalanges. Hand Clin 1994; 10:187–198.
18. Seno N, Hashizume H, Inoue H, et al. Fractures of the base of the middle phalanx of the finger: classification, management and longterm results. J Bone Joint Surg Br 1997;79B:758–763.
19. Weiss AP. Cerclage fixation for fracture dislocation of the proximal interphalangeal joint. Clin Orthop Relat Res 1996;327:21–28.