Hammer Toe Correction
DEFINITION
Hammer toe deformity is one of the most common lesser toe disorders. Its severity can range the gamut from asymptomatic to disabling.
Appropriate treatment of lesser toe disorders begins with determination of the exact joints involved and the plane of the primary and secondary deformities.
Sagittal plane deformities of the lesser toes are generally classified as hammer toes (FIG 1), claw toes (FIG 2), and mallet toes (FIG 3).
Specifically, a hammer toe is a lesser toe deformity in which a sagittal plane, flexion contracture of the proximal interphalangeal (PIP) joint, is the primary deformity.
A secondary, slight extension deformity of the metatarsophalangeal (MTP) joint may be present with a hammer toe, but this deformity is secondary and does not represent the primary deformity.
The primary deformity being at the level of the PIP joint differentiates a hammer toe from a mallet toe or claw toe, in which case the primary deformity is located at the distal interphalangeal joint or the MTP joint, respectively.
Hammer toe deformities are further classified as flexible or fixed depending on whether they completely correct with gentle, passive manipulation.
ANATOMY
The lesser toes comprise three articulating phalanges (distal, middle, and proximal) that, at the proximal phalanx, articulate with the metatarsal head. The only exception to this pattern is the fifth toe, which in about 15% of individuals comprises just two phalanges (distal and proximal).
The interphalangeal joints and their corresponding ligaments normally allow flexion but not extension past neutral, whereas the MTP joint complex allows both flexion and extension.
 |
FIG 1 • Hammer toe. The primary deformity is at the PIP joint.
 |
FIG 2 • Claw toe. The primary deformity is at the MTP joint.
Active motion of the toe and dynamic stability of the toe are achieved by both extrinsic muscles (originating in the leg) and intrinsic muscles (originating in the foot) (FIG 4).
The extensor digitorum longus and flexor digitorum longus are the extrinsic muscles.
The extensor digitorum longus invests the extensor hood over the proximal phalanx as well as inserting on the dorsal aspect of both the middle and distal phalanx (FIG 5), whereas the flexor digitorum longus inserts only on the distal phalanx.
The intrinsic muscles of the toes include seven interosseous muscles, four lumbricals, the abductor digiti minimi, the flexor digitorum brevis, and the extensor digitorum brevis.
PATHOGENESIS
Although the etiology of lesser toe deformities is multifactorial and includes neurologic, congenital, traumatic, and arthritic causes, the usual culprit for hammer toe deformity
72
is restrictive shoe wear that does not provide sufficient room for the toes.
 |
FIG 3 • Mallet toe. The primary deformity is at the distal interphalangeal joint.
 |
 |
FIG 4 • Cross-sectional anatomy of the lesser toe at the level of the metatarsal head.
Crowding of the toes in a shoe's toe box can be the result of poor shoe design, poor shoe fit, or a foot condition such as a hallux valgus deformity (and to a lesser degree, bunionette deformity) that crowds the toe box so that pressure is applied to the tips of the lesser toes and causes them to be passively flexed within the shoe for prolonged periods.
As the extensor digitorum longus, the primary extensor of the PIP joint, simultaneously inserts on the middle and distal phalanx, the flexion of the PIP joint by the pressure of the toe box is reinforced by the inability of the extensor digitorum longus tendon to extend the PIP joint when the proximal phalanx is not neutrally aligned (ie, the MTP joint is dorsiflexed).
This passive dorsiflexion at the MTP joint can occur from the pressure of the toe box on the toe as well as from elevation of the heel (eg, high-heeled shoe wear).
As flexible hammer toe deformity is generally well tolerated, the patient does not usually seek treatment during the initial development of a hammer toe.
With time, unless the factors that are stressing the toe are eliminated, the hammer toe will progress to a symptomatic fixed deformity.
NATURAL HISTORY
Hammer toe deformity generally worsens with time if the causative factors are not mitigated. Over time, the PIP joint flexion deformity will tend to increase and the toe will eventually progress from a flexible to a fixed deformity.
PATIENT HISTORY AND PHYSICAL FINDINGS
The most important information to elicit from the patient's history is whether the patient's complaints are solely
resulting from the hammer toe deformity or whether other sources of pain are present.
Occasionally, patients will present requesting surgery, having already made the diagnosis on their own. They experience pain in the foot and because the hammer toe deformity is the only abnormality they can see, they may conclude, sometimes mistakenly, that the hammer toe is the source of their pain.
 |
 |
FIG 5 • Dorsal view of a right lesser toe.
A good patient history includes the conservative treatment measures that have been tried, the types of shoes the patient wants to wear, the sorts of shoes the patient needs to wear for his or her occupation (ie, steel-toed shoes), and other patient factors that might be relative contraindications for surgery (eg, peripheral vascular disease) or would encourage you to pursue operative intervention (eg, history of ulceration).
Typically, patients with a hammer toe deformity present with a complaint of pain centered over the PIP joint that is relieved with removal of their shoes.
The degree of deformity generally corresponds to the degree of symptoms.
Symptoms of numbness and tingling in the foot, diffuse pain, pain that occurs at night, or pain that does not
improve with removal of shoes or shoe modifications raises concerns that the pain may be nonmechanical or emanating from a source other than the hammer toe.
Attempts by the patient to try different toe pads or different shoes should be noted in the history, as improvements in the patient's pain with more reasonable shoe wear helps to clarify the diagnosis as well as direct efforts for nonoperative care.
A history of neuropathy, peripheral vascular disease, systemic arthritides, and diabetes is important to elicit to assess for operative risk as well as to screen for other confounding sources of foot and toe pain.
Finally, a history of ulceration or infection needs to be elicited, as this may indicate a need for more urgent operative correction of the deformity to prevent recurrence.
The physical examination for hammer toe deformity, as with all foot and ankle examinations, begins with inspection of foot posture. Calluses, scars, and previous surgical incisions should be noted, as should the degree of the toe deformity.
Hallux valgus deformity and bunionette deformity need to be assessed as to their contribution to the crowding of the toe box.
73
With the patient standing, there must be enough room for the hammer toe to lie in the corrected position if surgically corrected. If a coexistent hallux valgus deformity prevents the hammer toe from being fully corrected, then the bunion must be surgically addressed at the same time as the hammer toe to avoid recurrence of the lesser toe deformity.
Palpation of the foot and toes should reveal a point of maximal tenderness over the PIP joint, and the ability or inability to passively correct the hammer toe to neutral should be recorded.
Finally, as with all foot examinations, pulses and foot sensation area are assessed. Methods for examining the hammer toe deformity include the following:
Palpation of the distal interphalangeal, PIP, and MTP joints for points of maximal tenderness. The PIP joint should be the area of maximal tenderness, but the tip of the toe may be painful as well.
Gentle manual straightening of the toe to assess the ability of the toe to correct to neutral. If the toe completely corrects to neutral, it is considered a flexible deformity. If the toe does not completely correct, it is considered a fixed deformity. A flexible deformity can be addressed with a soft tissue procedure such as a flexor to extensor tendon transfer, but a fixed deformity will require bone resection for surgical correction.
Push-up test: With the patient seated and knee flexed, the examiner dorsiflexes the ankle to neutral by applying pressure under the metatarsal heads. The correction of the toe deformity with this maneuver is noted. This will determine whether the deformity is fixed versus flexible and is also useful in the operating room to assess residual MTP joint contracture after the hammer toe has been corrected at the PIP joint. Residual MTP joint contracture necessitates additional surgical correction at the MTP joint such as extensor tendon lengthening, capsular release, or collateral ligament release.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Standing radiographs of the foot (anteroposterior [AP] standing, lateral standing, and an oblique view) are helpful to assess alignment of the toes as well as to rule out arthritis of the various toe joints.
Vascular studies of the lower extremity (transcutaneous PO2 readings and arterial Doppler studies with waveforms and toe pressures) are essential if surgical intervention is contemplated and there is any question
of vascular compromise.
DIFFERENTIAL DIAGNOSIS
Claw toe Mallet toe
Crossover toe deformity Degenerative joint disease Morton neuroma Neuropathy Radiculopathy
Vascular insufficiency Metatarsal stress fracture
MTP joint instability or synovitis
NONOPERATIVE MANAGEMENT
Ultimately, the treatment of a hammer toe deformity involves “making the shoe fit the foot, or the foot fit the shoe.”
Conservative treatment for a symptomatic hammer toe involves accommodating the deformity with a shoe the patient finds acceptable. Generally, an athletic-type shoe with a soft toe box will accommodate many mild deformities, whereas a prescription extra-depth shoe with an extra wide toe box will be needed to accommodate others.
Occasionally, softening of the leather upper of a shoe and stretching of the shoe over the area of the deformity will allow several millimeters of extra room for the toe, and in extreme cases, a “bubble patch” or cutout and elevation of a portion of the shoe toe box can give relief.
Silicone toe sleeves or toe pads can help relieve symptoms in mild deformities, but they are not usually successful for the treatment of fixed deformities as they tend to “stuff” the already crowded toe box and make the deformity more symptomatic.
SURGICAL MANAGEMENT
The primary indication for surgical correction of a hammer toe is a symptomatic (painful or preulcerative lesion) in a patient with adequate vascularity and realistic expectations who has failed to respond to conservative care.
Generally, patients with these problems tend to present having already attempted some type of conservative treatment or change in shoe wear. If they have not, it is worthwhile to educate the patient concerning the nature of the problem and conservative treatment options.
Generally, the most important determinant of postoperative patient satisfaction is a realistic preoperative expectation. When considering surgery, the patient should be told that by choosing surgery, he or she is electing to trade a painful, thin, deformed toe with some voluntary motion for a less painful (ideally pain free), short, scarred, possibly numb, swollen toe with little volitional control. The patient should not make the decision for surgery based on whether he or she wants a “normal” toe.
If the patient's preoperative expectations are too high, he or she should be advised to maximize conservative care and avoid surgery, as most likely he or she would be disappointed with the surgical outcome.
Preoperatively, the patient's shoe wear goals should be discussed, stressing that the goal of the operation is to allow the patient to wear “reasonable” shoes.
A patient with a coexistent hallux valgus deformity that does not allow adequate space for the lesser toe to move down onto the floor with surgical correction will have to have the hallux valgus deformity corrected at the time of the lesser toe surgery to avoid recurrence of the hammer toe.
In this situation, the hallux valgus deformity will have to be corrected even if it is asymptomatic. The patient needs to be counseled that correction of an asymptomatic hallux valgus deformity, to provide space for the hammer toe, may lead to a painful or numb great toe. (“It is difficult to make something that does not hurt better.”) Patients need to be aware of this possibility before electing surgery and consider it in their decision to have surgery.
74
With the decision made to proceed with fixed hammer toe deformity correction, there are primarily two surgical options: PIP joint resection arthroplasty and PIP joint arthrodesis.
With either option, the fixed nature of the hammer toe deformity requires resection of bone to shorten the toe so that, as it is straightened, the contracted, plantar neurovascular structures are not injured, which would occur with simply forcibly straightening the toe and pinning it without bone resection.
PIP joint resection arthroplasty involves resecting the distal condyles of the proximal phalanx, which relieves the deformity and often retains a small amount of motion at the PIP joint. This procedure has almost universally good results and is generally regarded as the gold standard for the correction of the majority of hammer toe deformities.
When it is desirable to have permanent, multiplanar stability at the PIP joint or to perform the procedure without the use of a postoperative stabilizing Kirschner wire, arthrodesis at the PIP joint may be a better option.
PIP joint arthrodesis involves preparation of the adjacent middle and proximal phalanx articular surfaces and some type of fixation to create stability at the fusion site. Several methods of fixation have been advocated, including Kirschner wire fixation and preparing the bone so that it interdigitates, such as in a peg and dowel
fusion,1 intramedullary screw fixation,3 or an interphalangeal implant such as the StayFuse implant (Tornier, Inc., Stafford, TX)2 (FIG 6).
The StayFuse implant is designed for PIP joint arthrodesis. It is composed of two matching titanium components that are individually inserted into the prepared middle and proximal phalanxes and then interlocked, creating stable PIP joint fixation.
 |
 |
 |
 |
FIG 6 • A. StayFuse implant. B. StayFuse Interdigital Fusion System: autoclavable case with (from top to bottom), 6-mm double-ended gray piloting bit, 1/8-inch chuck adapter, 5-mm double-ended gray piloting bit, universal driver handle, transfer template, double-ended blue piloting bit, large driver bit, and small driver bit. (From Briggs LC. Proximal interphalangeal joint arthrodesis using the StayFuse implant. Tech Foot Ankle Surg 2004;3:77-84.)
Table 1 Proximal Interphalangeal Joint Resection Arthroplasty versus Arthrodesis
The gold standard. The procedure of choice unless there is a special circumstance.
Arthrodesis indications
Arthroplasty indications
Situations with expected high recurrence rates (severe deformities and revision hammer toe surgery) Unacceptable elevated infection risk with external pin (diabetes, rheumatoid arthritis, or anticipated noncompliance)
Need for multiplanar stability (crossover toe deformity)
Arthrodesis is beneficial for patients for whom recurrence of deformity is likely, such as in severe deformity or revision hammer toe surgery. Situations in which a pin extending from the toe may pose an unacceptable infection risk, such as in a patient with diabetes mellitus, rheumatoid arthritis, or compliance issues, may benefit from arthrodesis with an implant spanning the PIP joint.
Fusion is also useful for crossover toe deformity correction, when destabilizing the PIP joint with a resection arthroplasty may result in a symptomatic angular deformity at the PIP joint, as crossover toe deformity invariably recurs with time.
Table 1 compares PIP joint resection arthroplasty and arthrodesis.
Preoperative Planning
With any toe surgery, adequate vascularity must be ensured before proceeding with surgery.
With lesser toe surgery, especially in the revision situation or if the patient has systemic conditions that might impair toe circulation, vascular injury to the toe and loss of the toe are possibilities and need to be discussed with the patient before the surgery.
For PIP joint arthrodesis with use of the StayFuse implant, a preoperative AP radiograph of the foot is useful to template the size of the implant. The proximal phalanx is templated first, keeping in mind that the bone will be a millimeter or two shorter after the bone resection and that the ideal implant fit would be to just engage the cortex of the phalanx.
The proximal phalanx and middle phalanx are each individually templated to assess the size of the canal and the appropriate implant width and length (Table 2). This, in turn, determines the size of the hand drill bit, which is color-coded gray or blue.
The goal is to find an implant that will fill the canal, but it is generally better to err on the side of a smaller and shorter
implant to avoid breaking the phalanx cortex and decreasing fusion site stability.
Table 2 StayFuse Implant Sizes
75
Middle Phalanx Size
Proximal Phalanx Size
2.8 × 11 mm (blue)
3.3 × 14 mm or 3.8 × 14 mm (gray)
3.8 × 6 mm or 4.3 × 6 mm (blue)
3.8 × 6 mm (gray)
4.3 × 6 mm (gray)
5.0 × 5 mm (gray)
5.0 × 6 mm (gray)
Positioning
Positioning of the patient is supine, with the patient's heel resting at the end of the operating table. A small, padded bump may be placed under the ipsilateral greater trochanter of the hip to internally rotate the foot to give better access to the dorsum of the foot.
The procedure can be easily performed with an ankle block or forefoot block with or without a tourniquet.
We generally prefer an ankle block and use an ankle Esmarch tourniquet if there are no vascular issues with regard to the toes; otherwise, we perform the procedure without a tourniquet.
Approach
PIP joint resection arthroplasty and PIP joint arthrodesis are both performed through a dorsal approach to the PIP joint. We usually mark out a curvilinear incision over the MTP joint as well, in case the extensor tendon or MTP joint capsule needs to be approached after the hammer toe correction to address any residual extension deformity at the MTP joint (FIG 7).
 |
 |
 |
FIG 7 • Skin markings for hammer toe surgery.
TECHNIQUES
-
Proximal Interphalangeal Joint Arthroplasty
Exposure
Make a straight longitudinal dorsal approach through the skin overlying the PIP joint, exposing the extensor tendon overlying the joint. The incision is about 1.5 cm long.
 |
 |
 |
 |
TECH FIG 1 • A. Dorsal approach for PIP joint arthroplasty exposing the extensor digitorum longus tendon. B. Releasing the collateral ligaments from the proximal phalanx with retraction of the extensor digitorum longus tendon. C. Releasing the plantar plate and exposing the proximal condyles. D. The proximal phalanx is cut at right angles while protecting the plantar soft tissues.
Generally, for hammer toe surgery, I use a longitudinal incision, but a transverse incision can be used (TECH FIG 1A). With the toe flexed, remove a transverse-oriented ellipse of skin over the dorsum of the PIP joint. The size of the ellipse depends on the amount of redundant skin but is generally about 3 mm wide.
This incision has the benefit of removing some of the redundant tissue overlying the PIP joint and may be more cosmetic, but it can make the hammer toe correction more
76
difficult if the incision is not placed directly over the proximal phalanx condyles.
With either initial incision, the remainder of the procedure for PIP joint arthroplasty is the same.
Retract the skin, and expose the extensor tendon and cut it transversely over the joint as the toe is slightly flexed.
Introduce a no. 15 blade into the joint between the collateral ligament and the underlying condyle of the proximal phalanx, releasing one side and then the other (TECH FIG 1B).
Direct the knife blade proximally, staying along the bone and not penetrating below the level of the plantar plate. Progressively flexing the toe to keep the collateral ligaments under tension helps make them easier to cut.
With the collateral ligaments released and the toe flexed, bluntly dissect the plantar plate off the neck of the proximal phalanx with a periosteal elevator to completely expose the proximal phalanx condyles (TECH FIG 1C).
Bone Resection
Resect the condyles using a sagittal saw oriented at a 90-degree angle to the axis of the proximal phalanx in both the coronal and sagittal planes at the metaphyseal-epiphyseal junction. A Freer elevator is placed under the proximal phalanx condyles to aid exposure and protect the underlying soft tissues while the bone is being cut (TECH FIG 1D).
At this point, if one is attempting to achieve more of an arthrodesis as opposed to a “true” arthroplasty, I will use a small osteotome to remove the cartilage on the base of the middle phalanx so that the subchondral bone is exposed.
Extend the toe to see if adequate bone has been resected. Ideally, gentle extension of the toe should bring the toe to neutral but not hyperextension. If the toe does not extend completely, if more than gentle extension is needed to do so, or if the toe seems to want to “spring back” to a more flexed position, additional bone can be resected, preferably a millimeter or two at a time until the toe is properly tensioned.
The goal is to remove enough bone so that the toe straightens completely without residual tension on the plantar soft tissues so that the deformity is corrected and the soft tissues are balanced.
Excessive resection of the bone can lead to postcorrection hyperextension at the PIP joint, which can make the patient symptomatic at the poorly padded plantar aspect of the PIP joint.
In addition, excessive shortening of the bone will result in varus-valgus instability of the toe, especially as the proximal phalanx resection moves from the metaphysis into the shaft of the proximal phalanx.
With adequate bone removed from the proximal phalanx, palpate the dorsal aspect of both the middle and proximal phalanges and smooth any bony prominences with a rongeur if necessary.
Kirschner Wire Insertion
Place a 0.045-inch Kirschner wire (a 0.062-inch Kirschner wire is used if the MTP joint is to be pinned) in the center of the articular surface of the middle phalanx and pass it across the middle phalanx through the distal phalanx and out the tip of the toe.
 |
TECH FIG 2 • Completed PIP joint resection arthroplasty hammer toe deformity correction. (After Briggs LC. Proximal interphalangeal joint arthrodesis using the StayFuse implant. Tech Foot Ankle Surg 2004;3:77-84.)
If one is trying to achieve an arthrodesis of the toe as opposed to a true arthroplasty and the cartilage has been removed from the base of the middle phalanx, I will use the Kirschner wire to create 2-mm deep perforations in the subchondral bone of the middle phalanx in 3-mm increments to increase the likelihood
of fusion, prior to placing the Kirschner wire centrally in the middle phalanx and advancing it out the tip of the toe.
Advance the Kirschner wire through the toe until it extends only a millimeter or two from the surface of the middle phalanx. Reduce the PIP joint to its neutral position and then drive the Kirschner wire back through the proximal phalanx shy of the MTP joint.
The pin position can be assessed with an AP fluoroscopic view (TECH FIG 2).
Perform a push-up test and assess the corrected position of the toe at the MTP joint. If the MTP joint corrects to neutral, proceed to closure; but if there appears to be extension at the MTP joint, that is addressed with an MTP joint soft tissue release.
Metatarsophalangeal Joint Soft Tissue Release
Make a curvilinear incision over the MTP joint about 2.5 cm long. Identify and lengthen the extensor digitorum longus tendon in a Z-fashion (TECH FIG 3).
I lengthen the extensor digitorum longus tendon by dissecting out the tendon and placing a sterile tongue depressor under the tendon to both protect the underlying soft tissues and assure myself that an adequate length of tendon has been exposed (about 2 cm).
Divide the tendon first longitudinally in halves and then cut it proximally and distally to create a Z-pattern cut.
 |
 |
TECH FIG 3 • Exposure of the extensor digitorum longus and brevis over the MTP joint.
77
Isolate the extensor digitorum brevis tendon, which travels lateral to the extensor digitorum longus tendon, and tenotomize it to further relieve any dorsiflexion contracture.
Perform the push-up test again, and if additional extension of the proximal phalanx at the MTP joint
remains, cut the capsule of the MTP joint transversely and release the dorsal third of the collateral ligaments on both sides of the metatarsal head in a similar fashion to how the PIP joint collateral ligaments were released in the initial part of the procedure (TECH FIG 4).
If the MTP joint has to be addressed, use a 0.062-inch Kirschner wire, instead of the 0.045-inch Kirschner wire, to pin the PIP joint and the MTP joint. The wire is usually placed 2 cm or more into the metatarsal, across the MTP joint to stabilize the joint. Pin the MTP joint while the ankle is held in neutral flexion and the toe is held in 5 degrees of flexion at the MTP joint.
 |
 |
TECH FIG 4 • Release of the dorsal portion of the collateral ligaments of the MTP joint after the extensor digitorum brevis has been tenotomized, the extensor digitorum longus Z-lengthened, and the MTP joint capsule released.
Closure
Close the PIP joint using a 4-0 plain suture to close the extensor tendon in one layer; then close the skin with simple 4-0 plain suture. If there is significant redundancy of the extensor tendon, a portion of it can be removed still allowing a loose closure over the PIP joint.
Close the extensor tendon at the MTP joint with a 2-0 nonabsorbable suture, followed by a 4-0 absorbable subcuticular closure and 4-0 nylon skin closure.
-
Proximal Interphalangeal Joint Arthrodesis
The surgical technique for the arthrodesis is identical to that for the arthroplasty with regard to joint exposure.
Bone Resection
After exposing the proximal phalanx condyles, use a sagittal saw to resect the proximal phalanx at the junction of the metaphyseal-epiphyseal junction as described previously.
In addition to exposing the proximal phalanx, arthrodesis requires exposure of the middle phalanx. This is exposed using sharp dissection to remove the soft tissue for a millimeter or two along the dorsal, medial, and lateral aspects of the middle phalanx (TECH FIG 5).
With the middle phalanx exposed, use a narrow sagittal saw blade to resect the articular cartilage and a millimeter or so of the subchondral bone. Be careful not to leave bony fragments or ledges in the depths of the wound, as these may later be prominent when the toe is fused.
With both the proximal phalanx and the middle phalanx exposed, bring the toe into extension to see if the bony surfaces adequately align and if overall toe alignment is acceptable.
Additional bony resection can be performed at this time.
Make sure enough bone has been removed to avoid excessive tension on the contracted plantar neurovascular bundles once the toe is realigned. Once the implant is engaged, it is difficult to remove it if the toe does not “pink up” after the removal of the tourniquet.
Although adequate bony resection is necessary, excessive bony resection should be avoided as it will lead to a cosmetically displeasing short toe.
Implant Site Preparation
After the bone resection, place a 0.062-in Kirschner wire down the center of the proximal phalanx to find the central axis of the bone. Use an AP fluoroscopic picture to confirm that the Kirschner wire is centrally placed and perpendicular to the cut surface.
Remove the Kirschner wire and use the hand drill to create a channel for the implant in the proximal phalanx (TECH FIG 6). Select the appropriate size implant as determined preoperatively.
 |
 |
 |
TECH FIG 5 • Preparation of the middle phalanx with sagittal saw.
78
 |
 |
TECH FIG 6 • Middle phalanx is prepared with the hand drill. (After Briggs LC. Proximal interphalangeal joint arthrodesis using the Stay-Fuse implant. Tech Foot Ankle Surg 2004;3:77-84.)
After making the channel in the proximal phalanx, place a double-sided punch (transfer template) in the channel. Reduce the cut surface of the middle phalanx and press it onto the exposed side of the double-sided punch (TECH FIG 7A). This scores the middle phalanx and indicates the proper insertion point for the middle phalanx implant.
Pay special attention to assessing the mediolateral translation of the middle phalanx on the proximal phalanx when scoring the middle phalanx. Ideally, the medial and lateral cortices of the adjacent phalanges should align to avoid symptomatic bony prominences once the joint is fused.
 |
 |
 |
 |
TECH FIG 7 • A. Transfer template is used to line up middle and proximal phalanx drill starting points. B.
Channel made in the middle phalanx.
After the middle phalanx has been scored, use the hand drill to prepare the implant channel for the middle phalanx (TECH FIG 7B).
Implant Insertion
With both sides prepared, insert the proximal phalanx implant first to avoid interference with its placement by the protruding flutes of the middle phalanx implant once it is inserted (TECH FIG 8A). Insert the proximal phalanx implant flush with the cut surface. The driver bit, which is used to insert the implant, is designed to disengage once the implant is flush with the level of the bone cut (TECH FIG 8B,C).
 |
 |
TECH FIG 8 • A. Insertion of the proximal phalanx implant. B. Fully inserted implant C. Seating of the implant flush with the cut bony surface. (After Briggs LC. Proximal interphalangeal joint arthrodesis using the StayFuse implant. Tech Foot Ankle Surg 2004;3:77-84.)
79
 |
 |
TECH FIG 9 • A. Both the proximal and middle phalanx implants are seated. The space between the flutes is oriented in the sagittal plane. B. The two implants are engaged with axial compression rather than levering the implants together. This avoids bending the implant. (After Briggs LC. Proximal interphalangeal joint arthrodesis using the StayFuse implant. Tech Foot Ankle Surg 2004;3:77-84.)
Place the middle phalanx implant with the body of the implant flush with the cut surface of the bone and the flutes of the implant exposed. The slot between the tines should be oriented in the sagittal plane as opposed to the horizontal plane to reduce the chance of the flutes bending as the implants are engaged (TECH FIG 9A).
The implants are then ready to be engaged. They are distracted and brought together, engaging the two components as horizontally as possible to avoid bending the flutes of the middle phalanx implant (TECH FIG 9B).
It is important not to lever the two components together, as this can lead to bending the implants, which can make it impossible to engage the two components. It is recommended to grasp the toe with
a 4 × 4 dressing sponge to give better hold of the toe as you manipulate it.9
As the flutes of the one implant engage the other, a ratcheting sound will be audible. Once the middle phalanx is sufficiently engaged in the proximal phalanx, the hexagonal base of the fluted component will attempt to engage the proximal phalanx component. Slight gentle rotation of the tip of the toe may be necessary to subtly rotate the middle phalanx implant and allow the hexagonal portions of the implants to engage (TECH FIG 10A).
If some twisting of the toe is necessary, after the hexagonal portions of the implants first engage, “derotate” the toe before the final compression is achieved so that the final compression of the toe is in the properly aligned position.
As the implant is fully interdigitated, the ends of the bones should visually come to rest together and the implant should fully engage, as evident on an AP fluoroscopic view (TECH FIG 10B).
A C-arm is usually used to confirm that the component is properly engaged and the toe is well aligned (TECH FIG 10C).
If the implants engage, but not fully, as long as a portion of the hexagonal section of the implant is engaged, this is acceptable. If there is only a slight gap at the bone fusion site, this is acceptable as well,
but I usually place some bone graft from the resected condyles to fill the gap.
With the toe implant inserted, palpate the bony dorsal surface of the toe to make sure that there are no protrusions; remove any bony prominences with a rongeur to create a smooth surface.
The remainder of the arthrodesis procedure is identical to the PIP joint arthroplasty, with the exception being that if the MTP joint must be addressed, it is done so without fixing it with a Kirschner wire, as the StayFuse implant will not allow the Kirschner wire to pass down the toe. In these cases, I extend the dressing sponges or abdominal (ABD) pads out over the toe with the dressing to provide a block to dorsiflexion of the toe. In the immediate postoperative period, I initiate taping of the toe in neutral position at the first postoperative visit and continue it for up to 3 months.
 |
 |
TECH FIG 10 • A. Toe with implant properly seated. (continued)
80
 |
 |
TECH FIG 10 • (continued) B. Implant securely engaged. C. AP radiograph of the second toe demonstrating proper implant engagement and good apposition of the bony surfaces. (After Briggs LC. Proximal interphalangeal joint arthrodesis using the StayFuse implant. Tech Foot Ankle Surg 2004;3:77-84.)
|
PEARLS AND PITFALLS |
||
|
|
Avoid ▪ Assess the circulation preoperatively. vascular ▪ Keep all dissection around the phalanxes subperiosteal. compromise ▪ Make sure there is adequate resection of bone at the PIP joint. The implant or Kirschner wire should only hold the correction that was obtained with the bone resection.
Avoid ▪ Do not lever the implant together, but distract, engage, and then bring the implant bending the together with it axially aligned. It is critical to position the middle phalanx implant's implant (PIP flutes so that the space between them is oriented in the sagittal plane. This will |
|
|
|
joint help keep the implant from bending as it is initially engaged. arthrodesis)
Selecting ▪ When using the radiographic template, remember to take into account the bone the proper- resection. Preoperatively, make sure the implant will not be too large for the toes. sized Although we have occasionally used the StayFuse implant for the fifth toe, most of implant (PIP the fifth toe phalanxes are too small for an implant. joint arthrodesis)
Avoid ▪ Make sure the base of the middle phalanx implant and the proximal phalanx incomplete implant are flush with the bone cut. The insertion device is designed to disengage engagement once the implant is at the proper depth, but occasionally, it will bury the implant too of the deeply. StayFuse ▪ If the implant only partially engages, but a portion of the hexagonal interface is implant (PIP engaged, this is acceptable if the bone has been brought into proper apposition. joint arthrodesis) |
|
|
|
||
81
POSTOPERATIVE CARE
Immediately postoperatively, the patient is advised to heel weight bear in a postoperative shoe.
For the first 2 days, activity is limited as the patient is advised to spend the majority of time with the foot up and elevated above the heart (23 out of the 24 hours).
After this, activity and elevation should be guided by swelling.
Sutures are removed at 2 to 3 weeks and any pins are removed at 3 weeks.
At 3 weeks, the patient can attempt to get into a loose tennis shoe but should be encouraged to wear the postoperative shoe as needed for comfort.
At 6 weeks, the patient can resume vigorous activity as tolerated.
In the case of an arthrodesis with an implant, radiographs are obtained at the first postoperative visit and at 6 weeks. If the patient is asymptomatic at that time and radiographs do not show signs of arthrodesis, further radiographs are probably unnecessary.
If the MTP joint has been addressed, we will strap the toe in a neutral position with cloth tape or a Budin splint for up to 12 weeks. We start this after the pin has been removed at week 3 or at the first postoperative visit if a pin has not been used.
OUTCOMES
Large, long-term studies4,8 on resection PIP joint arthroplasty and nonimplant arthrodesis have shown high satisfaction rates, in the range of 80% to 90%, with rare complications of infection, recurrent deformity, and problems inherent to Kirschner wire fixation.
Studies involving the use of the StayFuse implant have also shown equally high patient satisfaction rates.
The largest study of 150 implants in 140 patients reported a 95% patient satisfaction rate, 73% fusion rate, with a 3.3% revision rate at 18-month follow-up.6 Another StayFuse study of 38 implants reported
similar findings.5 A third study of only 28 implants reported significantly higher problems with implant failure both intraoperatively and postoperatively suggesting that use of the StayFuse implant is
technically more difficult to perform than traditional hammer toe resection arthroplasty.7
Review of the current StayFuse literature would suggest that strict adherence to proper technique is important and although the union rate is high, as with any fusion surgery, there is a risk of nonunion. In the case of the StayFuse implant, a majority of the nonunions will be asymptomatic, but a few will go on to demonstrate implant failure which may have symptoms sufficient to require further surgery.
When selecting PIP joint arthroplasty or nonimplant arthrodesis versus a StayFuse or implant arthroplasty, the surgeon must weigh the risks and benefits of the two procedures both of which have overall good results. PIP joint arthroplasty and nonimplant arthrodesis is technically easier to perform but carries the potential for complications inherent with Kirschner wire fixation and loss of deformity correction. PIP joint implant arthroplasty such as with the StayFuse implant while being more technically demanding has the advantage of more inherent stability at the fusion site but carries the disadvantage of the additional risk of implant failure as well as a significant expense for the implant itself.
COMPLICATIONS
Neurovascular compromise Prolonged recovery
Loss of volitional control Swelling
Recurrence of deformity Toe “too straight” Infection
Transfer lesion Nonunion Implant failure
REFERENCES
-
Alvine FG, Garvin KL. Peg and dowel fusion of the proximal interphalangeal joint. Foot Ankle Int 1980;1:90-94.
-
Briggs LC. Proximal interphalangeal joint arthrodesis using the StayFuse implant. Tech Foot Ankle Surg 2004;3:77-84.
-
Caterini R, Farsetti P, Tarantino U, et al. Arthrodesis of the toe joints with intramedullary cannulated screw for correction of hammer toe deformity. Foot Ankle Int 2004;25:256-261.
-
Coughlin MJ, Dorris J, Polk E. Operative repair of fixed hammer toe deformity. Foot Ankle Int 2000;21:94-
104.
-
Ellington MA, Anderson RB, Davis WH, et al. Radiographic analysis of proximal interphalangeal joint arthrodesis with an intramedullary fusion device for lesser toe deformities. Foot Ankle Int 2010;31: 372-376.
-
Fazal MA, James L, Williams RL. StayFuse for proximal interphalangeal joint fusion. Foot Ankle Int 2013;34:1274-1278.
-
Khan M, Walter RP, Loxdale P, et al. Early results of lesser toe proximal interphalangeal joint arthrodesis using an intramedullary device [abstract]. Bone Joint J 2013;95-B(suppl 9):10.
-
O'Kane C, Kilmartin T. Review of proximal interphalangeal joint excisional arthroplasty for the correction of second toe hammer toe deformity in 100 cases. Foot Ankle Int 2005;26:320-325.