Thomas R. Kiefhaber, Rafael M. M. Williams, and Soma I. Lilly
DEFINITION
Proximal interphalangeal (PIP) joint fracture-dislocations occur with the following fracture patterns9 :
Palmar lip fracture-dislocations: Fracture of the middle phalanx palmar lip with dorsal subluxation of the middle phalanx on the head of the proximal phalanx
Dorsal lip fracture-dislocations: Fracture of the dorsal lip of the middle phalanx with palmar subluxation of the middle phalanx
Pilon fractures: Pilon fractures include a loss of continuity of both the dorsal and palmar cortical margins of the middle phalangeal articular surface. The base of the middle phalanx usually is highly comminuted, and the articular fragments may be significantly impacted.
PIP fractures are further classified as “stable” or “unstable.”
Stable fractures maintain concentric joint reduction throughout the range of motion (ROM).
Unstable fractures sublux or dislocate during parts of the motion arc.
Dorsal lip fracture treatment is complicated by the need to re-establish continuity of the extensor tendon insertion onto the middle phalanx.
Pilon fractures are best treated with some form of traction and early motion.
Unstable palmar lip fractures are amenable to treatment with hemi-hamate autograft and are the focus of this chapter.
ANATOMY
The PIP joint is a complex hinge articulation that provides more than 95 degrees of flexion while maintaining stable, concentric reduction of the joint surfaces.
Several forces encourage dorsal migration of the middle phalanx: the extensor tendon lifts the middle phalanx and the mid-middle phalanx superficialis insertion levers the middle phalanx dorsally5 (FIG 1A).
The only restraints on middle phalangeal dorsal translation are the palmar plate and the cup-shaped geometry of the middle phalanx articular surface. The middle phalangeal palmar lip wraps around the proximal phalanx head and acts as a hook, preventing dorsal translation.
Palmar lip fractures disrupt both of the restraints to dorsal subluxation. The palmar plate is no longer attached, and the middle phalangeal palmar lip is disrupted. The slope of the remaining middle phalangeal articular surface encourages the middle phalanx to travel up and over the proximal phalangeal head.
A direct relation exists between the amount of palmar articular surface disrupted and stability (FIG 1B).
Hastings6 has shown that when 42% of the palmar articular surface is damaged, the joint always exhibits dorsal instability.
In the clinical setting, fractures with as little as 30% articular surface involvement can be unstable.
FIG 1 • A. Unstable PIP fracture-dislocation. The upward pull of the central tendon insertion and the distal superficialis insertion pull and push the middle phalanx up and over the proximal phalangeal head. The only forces preventing dorsal subluxation are the middle phalanx palmar lip and the palmar plate, both of which are lost in an unstable PIP palmar lip fracture. B. PIP instability after a fracture. A direct relation exists between the amount of middle phalanx palmar lip destroyed by the fracture and the resultant PIP joint stability. Articular damage in excess of 50% of the joint surface always renders the joint unstable, whereas fractures involving less than 30% usually are stable. Tenuous fractures (ie, those with articular damage of 30% to 50% of the joint surface), must be assessed with lateral radiographs. If the joint will not stay reduced with less than 30 degrees of flexion, it must be classified as “unstable.”
Hemi-hamate arthroplasty restores stability by rebuilding the cup-shaped geometry of the middle phalangeal base and restoring the palmar plate attachment.
PATHOGENESIS
The middle phalangeal palmar lip fracture that is associated with unstable dorsal PIP fracture-dislocations is created by either avulsion of the fracture fragment or an impaction shear mechanism.
Avulsion fractures result from PIP joint hyperextension and traction through the palmar plate attachment (FIG 2A).
The fracture fragment is not comminuted and represents less than 30% of the articular surface.
These injuries usually are stable and rarely require surgical intervention. If the joint is unstable, osteosynthesis with lag screws often is possible because of the lack of comminution and the substantial size of the fragment.
Impaction shear PIP fracture-dislocations result from a longitudinally applied load to the tip of the finger with the PIP joint slightly flexed, such as in a mishandled ball catch. The force drives the middle phalanx into and over the proximal phalanx head, resulting in a middle phalangeal palmar lip fracture that is highly comminuted (FIG 2B).
Up to 80% of the joint surface can be involved, and the articular fragments are often deeply impacted into the soft metaphyseal bone.
Disruption of the terminal extensor tendon (mallet finger) often occurs in association with unstable dorsal PIP fracturedislocations.
NATURAL HISTORY
The long-term prognosis for PIP fracture-dislocations is theoretically affected by the quality of the joint surface restoration and the maintenance of concentric reduction of the middle phalanx on the proximal phalangeal head.
The PIP joint seems to tolerate less than perfect restoration of a smooth joint surface. As long as motion is initiated quickly, small gaps and step-offs seem to be tolerated. Long-term, some remodeling occurs, and most patients do not need to be treated for symptomatic posttraumatic degenerative arthritis.
Joint reduction that is less than perfect is not well tolerated. When the middle phalanx rides dorsally on the proximal phalangeal head, PIP flexion occurs by “hinging” at the fracture margin.9 The joint pivots on the palmar edge of the fracture, and the proximal phalanx falls into the fracture defect at the palmar base of the middle phalanx. The proximal phalangeal articular cartilage suffers accelerated wear, while the remaining undamaged middle phalangeal articular surface remains unused throughout the motion arc (FIG 3).
Treatment of unstable PIP palmar lip fractures is directed toward re-establishing joint stability so that flexion occurs by “gliding” of the remaining middle phalangeal articular cartilage on the head of the proximal phalanx.
PATIENT HISTORY AND PHYSICAL FINDINGS
Assess alignment in the coronal plane. Lateral deviation suggests asymmetric compression of articular fragments.
FIG 2 • Fracture types. A. Avulsion fracture. Avulsion fractures usually are caused by a forced PIP joint hyperextension. The fragment is not comminuted and involves less than 30% of the joint surface. The PIP joint is most often stable. B. Impaction shear fracture. This type of PIP fracture-dislocation is caused by a longitudinal load to the joint. The fracture fragments are comminuted and impacted into the middle phalanx. The joint reduction often is unstable.
FIG 3 • Gliding or hinging. A. Normal PIP flexion occurs as the middle phalanx glides around the proximal phalanx head. B. When the middle phalanx palmar lip is lost, PIP flexion can occur by hinging at the fracture margin. Treatment of unstable PIP fracture-dislocations must rebuild the cup-shaped middle phalanx base and restore a normal gliding motion.
Assess alignment in the sagittal plane. Lack of colinearity of the middle and proximal phalanx suggests persistent joint subluxation or dislocation.
Associated mallet injuries must be treated concurrently with a DIP extension splint.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs in the posteroanterior (PA) and lateral planes provide the mainstay of radiographic evaluation of PIP fracture-dislocations.
Inspect the lateral radiograph to determine the percentage of joint surface fractured and the quality of the reduction.
If the joint is not concentrically reduced with less than 30 degrees of flexion, the joint is classified as unstable and must be treated appropriately (see FIG 1B).
On every lateral radiograph taken throughout the treatment course, carefully scrutinize the quality of the reduction. The remaining articular cartilage on the middle phalanx base must be in full contact with the proximal phalanx head. Any dorsal gap between the two surfaces—a “V” sign—indicates persistent instability and must be corrected (FIG 4).
The percentage of the middle phalanx articular surface consumed by the fracture can be used to predict joint reduction stability5,6,9 (see Fig 1B):
Less than 30%: The reduction usually is stable. The middle phalanx almost always remains concentrically reduced on the head of the proximal phalanx throughout a full ROM.
30% to 50%: The reduction is tenuous. The middle phalanx may or may not subluxate dorsally when the PIP joint is extended. If any subluxation is noted on the lateral radiograph with the PIP joint fully extended, flex the joint to 30 degrees and repeat the lateral radiograph.
If concentric reduction is achieved and the palmar fragments are sitting where they will reconstitute a palmar lip, some form of extension block treatment may be employed.
If the joint will not stay reduced with less than 30 degrees of flexion, the joint is unstable and must be treated accordingly.
Over 50%: The PIP joint is unstable, and surgical intervention usually is required to rebuild the cup-shaped geometry of the middle phalanx base and to reattach the palmar plate.
Inspect the PA view to determine asymmetric compression of middle phalanx articular fragments leading to varus or valgus angulation.
CT or MRI evaluation rarely is necessary.
FIG 4 • Unstable PIP palmar lip fracture-dislocation. Extensive damage has occurred to the palmar lip of the middle phalanx, but the dorsal cortical margin and a small amount of dorsal articular cartilage remain intact. Even slight dorsal subluxation can be detected by looking for a V-shaped gap between the middle and proximal phalanges.
DIFFERENTIAL DIAGNOSIS
In patients with a history of recent trauma and radiographic confirmation of a large PIP palmar lip fracture associated with dorsal subluxation, the diagnosis of an unstable PIP dorsal fracture-dislocation is obvious.
Dorsal dislocation and disruption of the middle phalanx palmar lip also may be seen in chronic PIP fracturedislocations and occasionally in association with various forms of arthritis.
NONOPERATIVE MANAGEMENT
Unstable PIP fracture-dislocations rarely can be managed nonoperatively. When over 50% of the middle phalanx articular surface is consumed by fracture, all restraints to dorsal subluxation are lost. The cup-shaped geometry of the middle phalanx base must be restored and the palmar plate reattached. Both goals can be accomplished with osteosynthesis of a single large fragment,2,3,8 palmar plate arthroplasty,1or a hemi-hamate osteochondral autograft.4,15,16
Stable PIP fracture-dislocations are treated nonoperatively. If the joint does not hyperextend and the lateral radiograph in full extension confirms concentric reduction, buddy tape the fingers and allow early ROM. If the joint hyperextends, some flexion must be maintained for 3 weeks while the fracture fragments consolidate enough to restore functional palmar plate continuity. Apply a dorsal blocking splint that prevents PIP hyperextension but allows full active flexion.
Nonoperative treatment of tenuous PIP fracture-dislocations requires careful thought, patient cooperation, and meticulous follow-up.
The primary treatment goal is to maintain joint reduction while the middle phalanx palmar fragments consoidate and restore the cup-shaped geometry of the middle phalanx base. Joint reduction must be achievable with less than 30 degrees of flexion, and the palmar fragments must fall into a position that will restore the middle phalanx palmar lip.
A secondary goal is to provide immediate active ROM. Any treatment method that prevents extension past 30 degrees and allows full flexion can be employed. Options range from simple extension block splints11 or pins14 to external traction12,13 or complex frame constructions.7,10
SURGICAL MANAGEMENT
Hemi-hamate osteochondral autograft is indicated for the treatment of unstable PIP fracture-dislocations. The middle phalanx dorsal cortex must be intact.
Hemi-hamate arthroplasty is a valuable salvage procedure for treatment that has failed with traction, external fixation devices, extension block splinting, or palmar plate arthroplasty.
Chronic PIP dorsal dislocations also are amenable to treatment with hemi-hamate autograft if enough intact cartilage remains on both sides of the joint. Undamaged cartilage must be present on the palmar 50% of the proximal phalanx head and on at least a small rim of the middle phalanx dorsal articular surface.
Preoperative Planning
Review the radiographs to determine the extent of articular surface damaged by the fracture, joint stability, and the quality of the remaining articular surface.
Patients with extensive pre-existing degenerative arthritis may be better served with a PIP arthrodesis or total joint arthroplasty than with hemi-hamate arthroplasty.
Assess the finger for radial or ulnar deviation. If coronal plane angulation is observed, it will be necessary to level the middle phalangeal joint surface during fracture site preparation and graft placement.
Examine the patient for a mallet finger. If the terminal extensor tendon has been damaged, plan to include a mallet splint in the postoperative regimen.
Positioning
Position the patient supine with the arm extended onto a radiolucent hand table.
A mini C-arm is required for the procedure.
Either regional or general anesthesia may be used, depending on the patient’s or surgeon’s preference.
Perioperative antibiotics are provided.
An upper arm tourniquet is applied. This is preferred over a forearm tourniquet, which puts pressure on the flexor muscles and causes excessive finger flexion.
If necessary, the dorsum of the hand is shaved at the fourth and fifth carpometacarpal (CMC) joints to facilitate harvesting of the graft.
Approach
We recommend performing the PIP portion of the procedure through a Brunner incision, because this incision provides excellent visualization of the fracture, the pulley system, and the neurovascular bundles.
The hamate graft is harvested through a transverse incision at the level of the fourth and fifth CMC joints.
TECHNIQUES
FRACTURE SITE PREPARATION
Use a lead hand to position the hand palm up with the fingers extended. It will be necessary to remove the lead hand intermittently to facilitate use of fluoroscopy.
Make a Brunner incision from the base of the finger to the DIP flexor crease (TECH FIG 1A)
Coagulate intervening vessels with bipolar cautery as the full-thickness flaps are elevated.
Identify the neurovascular bundles proximally and mobilize them away from the flexor sheath throughout the length of the dissection.
Divide Cleland’s ligaments dorsal to the neurovascular bundles. This allows full visualization of the collateral ligaments and facilitates retraction of the neurovascular bundles without excessive traction.
Retract skin flaps with 5-0 nylon suture.
Open the flexor tendon sheath from the distal end of the A2 pulley to the proximal edge of the A4 pulley. Start the dissection with a longitudinal incision along the edge of the flexor tendon sheath that is closest to the surgeon.
Create a flexor tendon sheath flap by making transverse incisions at the proximal end of A4 and the distal margin of A2. Elevate the flexor tendon sheath flap away from the surgeon (TECH FIG 1B).
Take care to prevent superficial damage to the flexor tendons while incising the flexor sheath.
With the flexor tendons retracted away from the midline, make longitudinal incisions down the lateral margins of the palmar plate to separate the palmar plate from the accessory collateral ligaments. The distal attachment of the palmar plate will already be detached (ie, avulsed) as a result of the injury, but it still may need to be gently mobilized. Leave any remaining bone fragments attached to the distal edge of the palmar plate.
If the fragments are large enough to accept interfragmentary screws, consider open reduction and internal fixation instead of proceeding with the hemi-hamate autograft.
Release the collateral ligaments distally. Leave a small stump on the middle phalanx to facilitate repair at the end of the procedure.
“Shotgun” the joint open (TECH FIG 1C).
Retract the flexor tendons away from the midline.
Hyperextend the PIP joint to expose the base of the middle phalanx and the head of the proximal phalanx.
If necessary, use a Freer elevator to prevent impingement of the intact dorsal base of the middle phalanx against the head of the proximal phalanx.
Caution: forceful hyperextension may lead to fracture of the dorsal articular fragment.
Only if absolutely necessary, release 1 to 2 mm of the A4 pulley to facilitate adequate mobilization of the flexor tendons. The A4 pulley is essential for finger function and must not be released completely.
Assess the damage to the articular surfaces of the middle phalanx and the head of the proximal phalanx.
Prepare the middle phalanx to receive the autograft (see TECH FIG 1C).
Elevate and excise impacted fragments of articular cartilage.
Use an oscillating saw to level the surface of the bony defect and to remove sufficient bone to allow graft placement. Make the cuts parallel to the dorsal margin of the articular surface and the long axis of the phalangeal shaft. Make the height of the intact articular surfaces equal at both the radial and ulnar margins. Limit thermal osteonecrosis with liberal use of irrigation.
The proximal to distal length of the cut usually is only about 5 to 7 mm. Take care to avoid notching the dorsal or distal portion of the cut, because this may weaken the shaft.
Carefully measure the defect in the middle phalanx base to determine the appropriate graft size. Make notes of the dimensions on a drawing created on the back table (TECH FIG 1D).
TECH FIG 1 • A. A Brunner incision, as depicted in this cadaver dissection, provides excellent visualization of the neurovascular structures, the flexor tendons, and the fracture site. B. Creating a flexor tendon sheath flap. Elevate a flap of the flexor tendon sheath from the distal end of the A2 pulley to the proximal edge of the A4 pulley. Preserve the flap so that it may be used to cover the palmar plate and the graft during closure. C. “Shotgun” the joint and prepare the fracture site. The PIP joint has been hyperextended 180 degrees to expose the fracture site. Note the palmar plate (A), the collateral ligaments (B) and the fracture defect (C). The fracture defect must be prepared so that it is of equal height and thickness on the radial and ulnar sides of the middle phalanx. D. Measuring graft dimensions. Measure the fracture defect to determine the medial-to-lateral width (A), proximal-to-distal depth (B). and anterior-to-posterior height (C) of the needed graft. Transfer these measurements to the dorsal surface of the hamate.
A : Width of the fracture defect. Measure the distance from the radial margin to the ulnar margin of the fracture defect. The graft must be centered on the central ridge of the proximal phalanx. Prepare the fracture site so that radial and ulnar extent of the fracture defect are equal.
B : The proximal-to-distal size of the defect. To avoid creating an uneven joint surface that causes angulation in the coronal plane, the proximal-to-distal defect size should be equal on the radial and ulnar margins or the middle phalanx.
C : Height of articular surface at the central ridge. Measure the distance from the dorsal aspect of the fracture defect to what would be the most palmar extent of the middle phalanx palmar lip. It will be necessary to estimate this based on a lateral view of the proximal phalanx and from the preoperative radiographs (percentage of joint involvement).
Return the joint to neutral and place a moist sponge on the finger incision while the graft is harvested.
HARVESTING THE HAMATE GRAFT
Identify the distal articular margin of the hamate with fluoroscopy and mark the skin with a transverse line.
Make a transverse 2-cm incision just proximal to the articular line.
Bluntly dissect to mobilize the subcutaneous nerves, vessels, and extensor tendons.
Longitudinally incise the hamate-CMC joint capsule, and then subperiosteally elevate the flaps to provide adequate visualization of the articular surfaces and the dorsum of the hamate (TECH FIG 2A)
The apex of the distal articular surface between the fourth and fifth metacarpal articular surfaces will become the new central ridge of the middle phalangeal base once the graft is transferred.
A 12-mm segment is trimmed from the flexible plastic ruler that accompanies the marking pen. A fine-tipped marker is preferred, because it will not bleed as much on the bone. Less soft tissue on the dorsum of the hamate also helps prevent the ink from bleeding.
Using a fine-tip marker and ruler, mark the dimensions of the graft on the hamate. To ensure stability of the CMC joints, leave at least 2 mm of the radial edge of the fourth metacarpal–hamate articulation and 2 mm of the ulnar edge of the fifth metacarpal–hamate surface.
Harvest a graft that is of adequate height to fill the middle phalanx defect, but do not fracture the dorsal cortex of the hamate.
Use an oscillating saw to make the cuts in the hamate very carefully. Alternatively, define the graft dimensions with a series of holes made with a K-wire, and then make the cuts with an osteotome (TECH FIG 2B).
To ensure that the graft is not too small, make the osteotomies on the outside of the measured lines.
Protect the articular surfaces at the base of the fourth and fifth metacarpals with a Freer elevator.
Estimate the depth of the cuts by marking the saw blade or osteotome and measuring how deeply it penetrates the hamate.
Create a notch in the hamate cortex proximal to the most proximal cut using a rongeur or by making an angled cut from proximal to distal with the saw. The notch is necessary to allow the final coronal cut to be made with a curved osteotome (TECH FIG 2C).
Using extreme care, make the final cut in the hamate and complete the graft harvest.
Gently advance an angled osteotome from proximal to distal, aiming to complete the cut through the distal hamate articular surface at the predetermined depth.
Protect the metacarpal articular surfaces with an elevator.
Take slightly more bone than needed. It is easier to trim excess than to deal with a graft that is too small.
Keep the graft protected in a moist saline sponge during wound closure.
After the wound is irrigated, securely close the capsule over the fourth and fifth CMC joints with a 4-0 braided, nonabsorbable suture. Close the skin in layers.
TECH FIG 2 • A. Exposure of the fourth and fifth metacarpal–hamate joints. Through a transverse skin incision and longitudinal capsular incision, as demonstrated in this cadaver dissection, expose the distal hamate articular surface and mark the graft dimensions. B. Use an oscillating saw or, as depicted in this cadaver dissection, K-wire holes and an osteotome, to make the cortical cuts in the dorsal surface of the hamate. C. Making the final hamate cut. A curved osteotome is used to make the final coronal cut that separates the graft from the hamate. It is necessary to make a back cut in the proximal hamate cortex to allow the osteotome to approach the cut at the proper angle. (A–C: wrist is to the left and fingers are to the right.)
GRAFT FIXATION
“Shotgun” the PIP joint open to expose the fracture site.
Carefully trim the graft with a rongeur or oscillating saw so that it fits precisely into the prepared defect at the middle phalanx base.
It is very important to tailor the graft so that it restores the cup-shaped contour of the middle phalanx base. Joint stability will be restored only by restoring a concave middle phalanx articular surface that includes a stout palmar lip (TECH FIG 3A–C).
A common error is to set the graft at an angle that creates a dorsal–proximal to palmar–distal slope. This carpentry error fails to restore joint stability and encourages the dorsal migration of the middle phalanx on the proximal phalangeal head (TECH FIG 3D,E).
Temporarily fix the graft with a centrally placed 0.028inch K-wire.
Lag 1.0 or 1.3-mm screws on either side of the provisional K-wire.
If the graft is large enough, augment the fixation with a third screw placed into the hole that remains once the Kwire is removed (TECH FIG 3F).
Relocate the middle phalanx on the proximal phalanx, and assess the joint for stability and alignment.
The joint should remain in position throughout a full ROM. Dorsal subluxation suggests that the graft has been set too flat, failing to restore a concave articular surface.
The joint should exhibit neutral alignment. Varus or valgus angulation suggests that the graft has not been set perpendicular to the long axis of the middle phalanx.
Assess screw length and graft placement with fluoroscopy. The hamate articular cartilage is thicker than the middle phalanx cartilage. This discrepancy creates the illusion that the hamate has not been set flush with the middle phalanx, but a lack of step-off already has been confirmed by direct inspection of the joint surface (TECH FIG 3G).
Often, the distal edge of the graft protrudes beyond the volar cortex of the middle phalanx fracture defect. Shave the graft edge to smooth the transition from graft to middle phalanx. PIP joint
TECH FIG 3 • A. This lateral preoperative radiograph demonstrates a chronic, unstable PIP fracture-dislocation in a 19-yearold woman. Joint flexion occurs as the middle phalanx hinges at the palmar fracture margin and the proximal phalanx falls into the fracture defect. B. The graft has been inset to recreate a middle phalanx articular surface that is concave and matches the curvature of the proximal phalanx head. C. The graft must be contoured and set into the middle phalanx in a manner that restores the cup-shaped geometry of the middle phalanx base. Failure to restore a concave joint surface creates a flat surface (D) that encourages dorsal subluxation of the middle phalanx (E). F. Relocation of the joint. The joint has been relocated and stability confirmed by taking the joint through a full range of motion and ensuring that subluxation does not occur. Note how nicely the hamate graft recreates the palmar lip of the middle phalanx. G. Lateral radiograph of the graft. The lateral radiograph gives the false appearance that a step-off exists between the graft and the remaining middle phalangeal articular cartilage.
CLOSURE
Repair the palmar plate and palmar margin of the middle phalanx. It may be necessary to secure the sutures through small drill holes.
Repair the collateral ligaments to the stumps that were left on the middle phalanx during the approach.
Interpose the flexor tendon sheath flap under the flexor tendons and over the PIP joint.
Obtain hemostasis after the tourniquet is deflated.
Close the skin.
Apply a bulky dressing and splint holding the PIP joint in slight flexion.
POSTOPERATIVE CARE
The goal of hemi-hamate arthroplasty is to operatively restore osseous PIP stability. Assuming that this goal has been attained and confirmed with lateral radiographs in extension that demonstrate concentric reduction, ROM is begun within the first week.
Apply a postoperative dressing that controls edema and supports the PIP joint in a slightly flexed posture.
Within the first week, begin active PIP flexion within an extension block splint that prevents extension past 20 degrees. The therapists may choose to fabricate a hand-based dorsal extension block splint if swelling is excessive, but a figureeight splint is preferable.
Encourage full active and passive motion at the MP and DIP. If a concomitant mallet injury is being treated, splint the DIP joint in full extension, but do not inhibit motion at the other joints.
If the radiographs at 3 weeks show concentric joint reduction and solid graft fixation, begin gentle active assisted ROM.
At 6 weeks postoperatively, again confirm solid graft fixation and concentric joint reduction radiographically, discontinue figure-eight splinting, and then begin passive ROM into flexion and correction of an excessive PIP flexion contracture with dynamic extension splinting.
OUTCOMES
We have previously reported the outcome of 13 patients with unstable PIP dorsal fracture-dislocations treated with hemi-hamate autograft.16 The original results were extremely encouraging, and our long-term results have not dampened our enthusiasm for the procedure.
Eleven of the 13 patients returned for examination and final radiographs, one patient’s results were assessed by chart review, and one patient was lost to follow-up.
Pain
Pain in the injured digit was minimal, and was rated at an average of 1.3. Two patients had regular pain, and six noted occasional aching discomfort.
Graft donor site aching discomfort was noted only rarely in three patients. The remaining patients were asymptomatic.
Motion
ROM in the PIP averaged 85 degrees (range 65 degrees to 100 degrees).
Most patients had a slight PIP flexion contracture that averaged 9 degrees (range 0 degrees to 25 degrees).
The ROM of the MP joint averaged 90 degrees (range 75 degrees to 100 degrees), and the motion at the DIP joint averaged 60 degrees (range 35 degrees to 80 degrees).
Stability
Two of 12 patients demonstrated slight dorsal subluxation on the lateral radiograph, but neither patient had symptoms or functional problems.
One of the two patients with dorsal subluxation also demonstrated 20 degrees of ulnar instability, but she was not symptomatic from this abnormality.
Radiographs
An apparent articular surface step-off between the graft and native middle phalanx cartilage commonly is observed. This phenomenon is caused by the greater thickness of the cartilage on the graft compared to the middle phalanx cartilage.
All grafts united, as demonstrated by bridging trabeculae.
None of the grafts demonstrated sclerosis that suggested osteonecrosis.
Graft reabsorption was not observed.
Long-term outcome
Our experience with PIP hemi-hamate arthroplasty is too short to definitively determine the ultimate fate of the transferred articular cartilage.
Early results do not suggest that autograft will lead to excessive rates of cartilage degeneration causing symptomatic posttraumatic changes.
COMPLICATIONS
The complication rate in our original patient cohort was low.16
No patients developed infection, and no patients required subsequent surgery.
Dorsal subluxation was noted in 2 of 12 patients. One was believed to have been caused by an incompetent palmar plate. The other case of dorsal subluxation was attributed to a graft that was not appropriately contoured to restore the cup-shaped geometry of the middle phalanx base.
Donor site morbidity has not occurred. To date, no patient has had instability or significant pain at the fourth or fifth CMC joints.
We have maintained an acceptably low complication rate in our subsequent experience.
REFERENCES
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