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Techniques in Foot & Ankle Surgery 7(1):31–40, 2008
Ó 2008 Lippincott Williams & Wilkins, Philadelphia
S P E C I A L F O C U S
j
j
Resurfacing of the First Metatarsal Head in the
Treatment of Hallux Rigidus
Carl T. Hasselman, MD
University of Pittsburgh Medical Center
Pittsburgh, PA
Naomi Shields, MD
University of Kansas
Wichita, KS
| ABSTRACT
Surgical techniques for the treatment of hallux rigidus
have evolved during the past decade. Previously, main
treatments were cheilectomy for earlier stages of hallux
rigidus and resection arthroplasty or arthrodesis for advanced stages. Although arthrodesis has been considered
the ‘‘gold standard’’ for advanced hallux rigidus, in
younger and more active patients, activity, functional,
and shoe wear limitations are undesirable outcomes of
this procedure. Alternative surgical procedures have
been developed for advanced hallux rigidus, with varying outcomes and complications. Endoprosthetic replacement, which has been well described in the past and
revisited recently, has higher complication rates than
more traditional approaches. Hemiarthroplasty using various prosthetic resurfacings of the phalangeal base has
been reported with variable success rates as well. Soft
tissue interpositional arthroplasty has been shown to
have inconsistent results and significant stiffness. The
Arthrosurface HemiCAP prosthesis has been described
for the treatment of full-thickness chondral and osteochondral defects of the shoulder, hip, and knee with
high success rates to date. More recently, the technology
was expanded to allow for metallic resurfacing of the
first metatarsal head as an alternative technique with
the potential to maintain motion and function. By using
this implant alone or combined with soft tissue interpositional arthroplasty, or proximal phalanx osteotomies,
even severe forms of hallux rigidus can be treated. During the past 30 months, the authors have treated more
than 100 patients with hemiarthroplasty of the first metatarsophalangeal joint using the HemiCAP prosthesis
(Arthrosurface Inc, Franklin, Mass). To date, there have
been 2 failures, one from infection and the other from a
Address correspondence and reprint requests to Carl T. Hasselman,
MD, University of Pittsburgh Medical Center, Pittsburgh, PA 15215.
E-mail: hasselmanct@upmc.edu.
related procedure. Twenty-five of the first 30 patients
with stage II or III hallux rigidus consented to participate in a follow-up study. The mean age of these patients
was 51 years. Mean follow-up was 20 months. The mean
postoperative increase in range of motion of the joint
was 42 degrees (baseline, 23 degrees; postoperative, 65
degrees). The mean American Orthopaedic Foot and
Ankle Society and 36-item Short-Form Health Survey
Questionnaire scores were 82.1 and 96.1, respectively.
All patients were very satisfied with their results and
said that they would have the procedure performed
again. Although long-term follow-up is still needed, the
short-term results are very promising. In addition, future
treatment options are maintained because of minimal
bone resection at the time of HemiCAP implantation,
and conversion to arthrodesis or resection arthroplasty
can be performed should the need arise.
Keywords: hallux rigidus, first MTP joint, endoprosthesis, HemiCAP, Arthrosurface, hallux limitus, resurfacing,
hemiarthroplasty, arthritic bunion
H
allux rigidus is a progressive arthritic process of
the first metatarsophalangeal (MTP) joint that
causes pain, stiffness, and enlargement of the joint.1,2 A
multitude of surgical procedures has been described to
address the pain and stiffness associated with this disease,
including cheilectomy, 3,4 osteotomies, 5,6 resection
arthroplasty,7,8 interpositional arthroplasty,9Y11 hemiarthroplasty, 1 2 , 1 3 total joint arthroplasty, 1 4 , 1 5 and
arthrodesis.16Y18 Although cheilectomy and osteotomies
may be suitable for stages I and II hallux rigidus, these
procedures are not effective for the treatment of more advanced stages.19 Because resection arthroplasty has been
associated with transfer metatarsalgia, postoperative deformities, and loss of push-off strength, its use has been
recommended only for elderly and sedentary patients.20
Interpositional arthroplasties have recently been gaining
popularity. However, long-term follow-up studies are
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Special Focus: Hasselman and Shields
lacking for the newer techniques. Hemiarthroplasties
that resurface the proximal phalangeal base have
shown promise as well, but stiffness, continued pain,
and prosthetic loosening are still limiting factors associated with these procedures. Total joint arthroplasties
have been fraught with complications in the younger
and more active patients with loosening and malalignment common in endoprosthetic replacement.14,21 Arthrodesis has been considered the ‘‘gold standard’’ for
treating advanced hallux rigidus. However, limitations
in shoe wear, permanent activity modifications, complications of malunion or nonunion, and transfer metatarsalgia have made this procedure less attractive to the
younger active patient.22Y25 A treatment alternative
that can reliably relieve pain, maintain motion without
affecting strength or stability, while maintaining future
treatment options is greatly needed for this patient
population.
In advanced stages of hallux rigidus, the metatarsal
head is severely denuded of its articular cartilage; however, the sesamoid articulations are usually spared
except in the most extreme cases. Quite often, the metatarsal head is the more damaged side of the joint. The
use of acellular human tissue has recently been described
to resurface the metatarsal head with good immediate
results10; however, the short- and long-term wear on
such a graft is still in question. A metallic implant to resurface the metatarsal head with minimal bone resection and without altering the sesamoid articulation was
needed. The implant should also not interfere with the
normal balance of the flexor-extensors, plantar plate, or
adductor-abductor mechanisms. The HemiCAP System
(Arthrosurface Inc, Franklin, Mass) was introduced several years ago to resurface damaged articular surfaces
and restore the patient’s own unique joint geometry
with minimal bone resection. The implant is composed
of a cobalt-chromium alloy for the articular portion,
which attaches to a titanium alloy taper post (fixation
component) via a Morse taper (Fig. 1). Earliest uses
were in the shoulder, hip, and knee, with encouraging
clinical outcomes.26Y29 Thirty months ago, the device
was approved and introduced for resurfacing of the
metatarsal head in hallux rigidus. We present our early
experience with this new technique on inlay resurfacing
of the metatarsal head.
| INDICATIONS AND
assessed to determine his or her desired outcome from
the procedure. The ideal patient for this procedure
demonstrates signs and symptoms of advanced hallux
rigidus and expects to remain active and maintain motion. This patient opposes permanent limitations in
shoe wear and physical activities and fears the limited
weight bearing associated with the immediate postoperative care.
Absolute contraindications for this procedure include significant bone demineralization or inadequate
bone stock, neuropathic changes of the foot, metal sensitivity, and a history of osteomyelitis or persistent infection. Relative contraindications include infections at
remote sites that may spread to the implant, osteoporosis, chronic instability of the MTP joint, and vascular
disease that would impair wound healing. Gout and inflammatory arthritis may be relative contraindications;
however, the authors have used the HemiCAP in a
small number of these patients. These patients typically
have less postoperative range of motion than most, but
their motion has been adequate for activities of daily
living. Although a previous failed osteotomy and/or
cheilectomy is not a contraindication, the soft tissues
should be adequate to allow for wound coverage and
healing before performing this procedure. The patient
should also be counseled that this technique is relatively
new, and although early results are promising,30 longterm outcomes are still lacking.
| PREOPERATIVE PLANNING
CONTRAINDICATIONS
HemiCAP implantation is indicated in patients with
stages II to IV hallux rigidus who have failed conservative treatment, including activity limitations, shoe
wear modifications, and nonsteroidal anti-inflammatory
medications. 1 Each patient should be individually
32
FIGURE 1. The HemiCAP implant: titanium alloy fixation
component connected via Morse taper to the cobalt
chromium alloy articular contoured component.
A full preoperative assessment of the patient includes
general health, comorbid conditions, and physical examination of the entire lower extremity to ensure optimal
outcome. However, there are no age limitations for this
implant, and preoperative range of motion has not been
found to have any effect on postoperative results. Dorsal
Techniques in Foot & Ankle Surgery
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Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus
| TECHNIQUE
FIGURE 2. Anteroposterior and lateral radiographs of
young female and avid runner who developed avascular
necrosis and subsequent arthrosis of the metatarsal head
after a distal chevron osteotomy for hallux valgus.
pain of the first MTP joint with increased activities,
barefoot walking, or soft sole shoe wear are the classic
complaints. The sesamoid articulation should be assessed by direct palpation while manually dorsiflexing
the toe to ensure that this articular surface is not a
major source of the patient’s symptoms. If the sesamoids
seem to be involved in the arthritic process, then other
procedures along with the HemiCAP or arthrodesis
should be planned; however, sesamoid involvement
with the arthritic process is not a contraindication to
this technique. Preoperative weight bearing anteroposterior, oblique, and lateral radiographs should be
taken to evaluate the joint and rule out other causes
of pain (Fig. 2). Evaluation of joint alignment is important. If there is an increased intrametatarsal angle
or halgus valgus deformity, alignment correction of the
joint must be done either in conjunction with or before
the cheilectomy or HemiCAP arthroplasty. Intraoperative assessment of the metatarsal articular surface will
further guide the surgical management plan: if less
than 50% of the metatarsal head is involved and good
articular surface remains plantarly, a cheilectomy should
be performed; whereas HemiCAP implantation is indicated in patients with advanced loss of articular cartilage. Although the HemiCAP implant is available in
12- and 15-mm-diameter sizes to accommodate most
metatarsal head dimensions, it has been our experience
that the 15-mm size has been used predominantly. The
12-mm implant works best in cases of an isolated central osteochondral defect of the metatarsal head. In addition, a smaller fixation component in combination
with the 12-mm implant has been successfully used in
the treatment of Freiberg’s disease of the second metatarsal head.
The patient is placed supine on the operating table, with
the operative extremity in a well-padded position. The
procedure can be done with either a regional popliteal
block and a calf tourniquet or an ankle block with an
Esmarch bandage wrapped around the ankle. A dorsal
incision is made centered over the MTP joint and slightly medial to the extensor hallucis tendon. The subcutaneous tissues are spread gently to expose the dorsal joint
capsule, with care being taken to protect the dorsomedial
cutaneous nerve. The extensor hallucis longus tendon is
freed from the capsule and retracted laterally to keep the
tendon within its sheath (Fig. 3). A longitudinal arthrotomy is made along the medial border of the joint, and the
capsule is elevated off the bone. A complete release of the
collateral ligaments, sesamoidal suspension ligaments,
and capsule should be made so that the entire joint, including the sesamoids, is easily visualized (Fig. 4). It is very
important to visualize the articular edge of the sesamoid
Christi on the metatarsal head because this is the landmark
for placement and sizing of the implant. In advanced hallux rigidus, the sesamoids and flexor hallucis brevis will
have fibrotic adhesions to the metatarsal head that will
limit dorsiflexion postoperatively. A curved osteotome,
freer or McGlammary elevator can be used to release
these plantar adhesions. Care should be taken to avoid
damage to the metatarsal-sesamoid articulation. A cheilectomy is not performed at this time to avoid overresection of bone.
Once the joint is exposed, HemiCAP implantation is
performed after the stepwise arrangement of the instrument set from left to right in the system tray.
A cannulated drill guide is used to establish perpendicular access to the joint surface and to place a guide
wire into the center of the metatarsal head (Fig. 5).
FIGURE 3. Intraoperative photograph showing incision
placement, capsular exposure, and retraction of the
extensor hallucis longus.
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Special Focus: Hasselman and Shields
FIGURE 4. Complete release of the soft tissues to
expose the entire joint. The collateral and plantar
ligaments should be completely released.
FIGURE 6. The guide wire is viewed dorsally to ensure
that the wire is centered in the metatarsal shaft in the
medial/lateral plane.
Once the guidewire is inserted, obtain fluoroscopic anteroposterior and lateral views to ensure that it is centered
within the shaft in both the dorsal-plantar and mediallateral directions (Fig. 6). A cannulated double-step
drill is inserted over the guide wire, and the metatarsal
head is drilled until the proximal shoulder of the drill
is flush with the plantar articular surface of the metatarsal head (Fig. 7). In most cases, the only normal articular surface remaining is the plantar cartilage, and this
surface is used as the reference for depth determination.
The drill is removed, and a cannulated tap is inserted
over the guide wire. The hole is tapped until the etched
depth mark on the tap is flush with the plantar articular
surface of the metatarsal head. The tap is removed, and
the taper post is inserted over the guide wire. The taper
post is inserted until the etched line on the driver is flush
with the articular surface of the metatarsal head (Fig. 8).
The apex height of the final implant relative to the native articular surface can be checked at this time by
using a trial cap provided with the taper post.
With the taper post in place at the desired depth,
3-dimensional mapping of the metatarsal head determines the curvatures of the native surface geometry. A
centering shaft is fully seated in the cleaned taper of
the fixation component. The contact probe is placed
over the centering shaft, and the probe tip is used to
map the normal articular surface of the metatarsal head
(Fig. 9). Although the technique manual refers to 4 contact areas (dorsal, plantar, medial, and lateral) in most
cases of hallux rigidus, only 2 surfaces still have healthy
articular cartilage, the plantar surface and either the
medial or lateral side of the joint. Measurements of
the joint offsets in the inferior and medial/lateral surfaces are now made. Using a sizing card provided
with the implants, the appropriate shaped implant and
FIGURE 5. Intraoperative photograph showing the drill
guide firmly seated against the metatarsal head in the
position desired for implant placement.
34
FIGURE 7. The drill is driven until seen flush against the
articular surface as shown.
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Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus
FIGURE 8. The taper post is placed. Note that the post is
advanced until the line on the driver is flush with the
articular surface.
FIGURE 10. The sizing card with offset measurements
showing that a size 1.5-mm 3.5-mm implant should be
used. The reamer size is based on the largest offset of the
implant chosen.
corresponding reamer are now chosen (Fig. 10). The
centering shaft and contact probe are removed, the
guide pin is reinserted into the taper post, the corresponding reamer (based on the offset measurements) is
placed over the guide pin, and the implant bed is prepared in the metatarsal head (Fig. 11). The reamer is
attached to a high speed drill and should be running
at full speed before contact with the metatarsal head to
avoid shearing or shattering of the bone or remaining
articular surface. The reamer can be very aggressive,
so gentle pressure should be exerted while slowly advancing the reamer over the guide pin. Care should be
taken to maintain a proper axis and not bend the guide
pin while reaming. The reaming will stop upon contact with the top of the taper post. The guide pin and
reamer are now removed, and the taper is cleaned. All
reamings are removed from the wound, and frayed
edges of the articular surface are cleaned (Fig. 12). A
sizing trial that matches the offset profile of the chosen
implant is now seated into the taper post to ensure
proper orientation and fit of the implant. The fit of
the sizing trial is confirmed by ensuring that it is congruent with the edges of the surrounding articular surface. Again, in most cases, this will be the plantar and
medial/lateral surfaces.
Although it is not necessary in most cases, decompression of the joint is possible by altering the joint
line and driving the taper post deeper into the metatarsal
head. The taper post driver is placed back onto the taper
post and turned clockwise. For every quarter turn of the
driver, the taper post advances 1 mm deeper. It is not
recommended to decompress the joint more than 2 or
3 mm to avoid altering the sesamoid articulation. Once
the taper post has been advanced, it is necessary to repeat the reaming step to ensure that the articular component is properly seated in the taper post and implant bed.
FIGURE 9. The centering post is inserted into the taper
post with the contact probe measuring the offset of the
plantar surface.
FIGURE 11. Reaming of the metatarsal head over the
guide wire.
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Special Focus: Hasselman and Shields
FIGURE 12. The reamed metatarsal head and taper post
are cleared of all debris before seating the implant.
FIGURE 14. The implant is seated in the taper post
before cheilectomy.
Once the sizing trial confirms proper fit of the implant, the trial is removed, and the area is cleaned once
again, with focus on the taper to ensure proper seating
of the final implant. At this time, a full cheilectomy of
the metatarsal head is performed over the sizing trial,
thereby avoiding any damage to the actual implant.
The articular component is placed in the appropriate
medial/lateral and dorsal/plantar orientation using the
suction-holding device provided with the instrument set
(Fig. 13). An impactor is used on the implant with gentle taps to ensure that the implant is fully seated on the
taper post and bone bed (Fig. 14). The cheilectomy is
checked with the implant in place to ensure an adequate
resection of bone (Fig. 15). Bone wax can be placed on
the resected surface of the metatarsal to minimize postoperative hematoma formation (Fig. 16).
At this time, attention is turned to the phalangeal side
of the joint. Many different approaches can be taken to
address phalangeal pathology. Some surgeons perform
a cheilectomy of the proximal phalanx. This is usually
successful if less than 50% of the articular cartilage is
damaged. Other surgeons have combined a Moberg
proximal phalangeal osteotomy 5 with the HemiCAP
technique to improve postoperative range of motion.
If more than 50% of the proximal phalanx surface is
involved, we combine the HemiCAP implant with a soft
tissue resurfacing of the proximal phalanx. A saw is used
to remove the dorsal osteophyte, similar to what has
been described by others (Fig. 17).9Y11 Do not resect
the plantar cortex to avoid disrupting the flexor attachment. A portion of dorsal capsule large enough to
cover the proximal phalanx base is completely excised
(Fig. 18) and sutured to the base of the proximal phalanx
(Fig. 19). Suture anchors placed centrally or drill holes
in the corners are used to secure the capsule in place
with sutures. Previously, metallic suture anchors were
FIGURE 13. The implant is being held by the suction
holding device. The orientation of the implant is imprinted
on the inside to allow verification of proper alignment.
FIGURE 15. A lateral view of the metatarsal showing the
appearance after a full cheilectomy is performed to
remove any osteophytes or nonarticular cartilage that
contacts the implant.
36
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Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus
FIGURE 16. Dorsal view of the metatarsal after cheilectomy and application of bone wax to the cut surfaces.
used, but because of a rare experience with metallosis caused by the anchors contacting the implant,
bioabsorbable anchors are now recommended. If the
capsule is inadequate to cover the phalangeal base because of previous surgical interventions, an acellular
dermal allograft (Graft Jacket, Wright Medical) or xenograft (Zimmer Patch, Zimmer Inc or Surgimend, TEI
Biosciences) can be used as a soft tissue interposition.
In several cases of severe sesamoid involvement, the
technique of Berlet et al10 was added to the HemiCAP
procedure to provide soft tissue interposition for the
sesamoids. However, it remains unclear if this provides
any long-term benefits.9
Once the phalangeal side has been addressed, the
joint is taken through a range of motion. Intraoperatively,
90 degrees of dorsiflexion between the metatarsal and
phalanx should be achieved. The wound is now copiously irrigated and closed in layers. In most cases where the
FIGURE 17. Resection of the dorsal osteophytes of the
phalangeal base. Note that articular cartilage persists on
the plantar 25% of the base.
FIGURE 18. The dorsal capsule is cut to the size of the
phalangeal base. Hemostats are placed in each corner
to prevent the graft from rolling up once it has been prepared. Suture anchors have been placed into the proximal phalanx base to secure the graft.
capsule has been removed for phalangeal resurfacing,
there is still adequate capsule for closure because of the
redundancy of the capsule after the cheilectomy has
been done. A compressive, but not bulky (to allow free
dorsiflexion), dressing is applied, and the patient is encouraged to fully weight bear postoperatively.
| POSTOPERATIVE COURSE
A stiff-soled shoe is provided for comfort and outside
ambulation, but full weight bearing without a shoe in
the household is encouraged immediately to prevent
joint stiffness. The patient is encouraged to use a heel
to toe gait and not walk on the side of their foot. The
patient is instructed in passive dorsiflexion of the joint
preoperatively, and these instructions are repeated
FIGURE 19. The graft is laid on the base and sutured into
place. The hemostats are not removed until the graft is
secured.
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Special Focus: Hasselman and Shields
immediately postoperatively. Passive and active dorsiflexion and plantarflexion of the joint is encouraged immediately postoperatively. This early joint mobilization
has not interfered with normal wound healing, and few
wound complications have been seen by early mobilization of the joint. The skin suture is a running subcuticular absorbable stitch, and therefore suture removal is not
needed. The patient is seen 2 weeks postoperatively, and
formal physical therapy is prescribed for range of motion and strengthening as needed. No bracing is used
for the hallux postoperatively to maintain alignment,
and no postoperative deformities have been seen by
the authors. Weight-bearing postoperative radiographs
of the foot are taken at 6 weeks to ensure appropriate
alignment (Fig. 20). In the study patients, postoperative
radiographs are repeated at intervals according to the
study protocol.
| COMPLICATIONS
As with any surgical procedure involving a joint, the
potential complications include infection, stiffness, persistent pain, and neurological injury. With this particular
technique, the most common complication has been loss
of intraoperative dorsiflexion; however, the range of
motion seen postoperatively even in these patients has
been adequate and without activity limitation. Other
complications have been local wound infections that
have resolved with oral antibiotics and local wound
care. A rare complication previously mentioned is the
use of metallic suture anchors with the HemiCAP implant. The suture anchors contacted the implant, and a
metallosis reaction occurred that required removal of
FIGURE 21. Postoperative lateral fluoroscopic view
showing passive dorsiflexion of the first MTP joint with
the HemiCAP in place. Note that the sesamoids glide over
the implant, and dorsiflexion is at least 90 degrees in this
patient.
the implant and arthrodesis. Since then, bioabsorbable
suture anchors have been used. Some patients complained of mild to moderate plantar pain felt to be related to sesamoid pain or flexor tendonitis that resolved
after 2 to 3 months. No loosening of any implants has
been observed since the introduction of this new technique 30 months ago.
Should this implant fail because of persistent pain,
swelling, or other reasons, then surgical options include
either Keller resection arthroplasty or arthrodesis. The
latter could be done by either shortening the hallux and
primary bone apposition using conical reamers or using a
bone block interposition to maintain hallux length.
| RESULTS
FIGURE 20. Postoperative anteroposterior and lateral
radiographs of the patient seen in Figure 2. Note that the
implant has resurfaced the damaged metatarsal head.
Alignment is restored. This patient has returned to normal
activities. The metallic suture anchors are no longer used
for the interposition graft.
38
During the past 30 months, more than 100 patients have
undergone hemiarthroplasty of the first MTP joint using
the HemiCAP prosthesis at our institutions. Conditions
treated included hallux rigidus, arthritic hallux valgus,
failed previous osteotomies and cheilectomies, and avascular necrosis of the metatarsal head and failed fusion
caused by increased pressure on the proximal phalanx.
To date, in more than 100 patients, there have been 2
failures, one from infection and the other from metallosis. Twenty-five of the first 30 patients with stage II or
III hallux rigidus consented to participate in a followup study. The mean age of the patients was 51 years.
Occupations included carpenters, housewives, physicians, executives, and manual laborers. Patient assessment was conducted with the American Orthopaedic
Foot and Ankle Society and 36-item Short-Form Health
Survey Questionnaire outcome measures, physical examination, and radiographic evaluation performed preoperatively and at 1, 3, and 6 months, and 1 and 2
Techniques in Foot & Ankle Surgery
Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus
years postoperatively. Mean follow-up was 20 months.
All patients are very satisfied with their results and said
that they would have the procedure performed again.
The mean postoperative increase in range of motion of
the joint was 42 degrees (baseline, 23 degrees; postoperative, 65 degrees). The mean American Orthopaedic
Foot and Ankle Society and 36-item Short-Form Health
Survey Questionnaire scores were 82.1 and 96.1, respectively. These results suggest that short-term outcomes
with this technique are as good as or better than other
joint-sparing techniques.
| CONSIDERATIONS AND
FUTURE DIRECTION
The HemiCAP prosthesis, as the first metatarsal head
resurfacing implant, is a novel approach to the treatment of arthritis of the first MTP joint. All other hemiarthroplasty implants have resurfaced the phalangeal
base. Quite often, pain and stiffness, although lessened,
still persist with proximal phalanx implants.12,13 Our
experience with the HemiCAP implant to date revealed
superior postoperative range of motion and pain reduction when compared with the other implant hemiarthroplasties (Fig. 21). One possible explanation is that
hallux rigidus pathology and cartilage loss is primarily found on the metatarsal head, and by resurfacing
this side, the damaged cartilage is removed and a
smooth and congruent new joint surface is created. Furthermore, impaction of the proximal phalanx on the
metatarsal head is thought to be a major etiologic factor in the development of hallux rigidus. Hemiarthroplasty techniques that resurface the proximal phalanx
base still leave damaged metatarsal cartilage. The impaction of the implant onto the remaining damaged
metatarsal head could be a leading cause for persistent
pain with those implants. Metatarsal head resurfacing
may therefore explain further improvement in postoperative pain relief.
There have been no reports of implant loosening or
osteolysis around the HemiCAP implant to date. In contrast, studies on phalangeal-sided hemiarthroplasty report
loosening of the implant as a significant problem even
with short-term follow-up.12,13 It is possible that the
shear stresses seen in the proximal phalanx with repetitive dorsiflexion cause the implant to loosen or prevent
proper bony ingrowth early on. Historically, the phalangeal component of metallic implants that resurface both
sides of the joint has been prone to loosen. The metatarsal side does not see the shear stresses on the boneimplant interface, which may explain improved fixation
and osseous integration. Further studies are needed to
explore this possibility. In addition, the high-pitched
screw fixation component may provide a stronger con-
struct than traditional keeled or pegged cementing techniques. It is because of this novel implant design that we
think this implant works well even in the conditions of
repetitive stresses. Some patients have been recreational
runners. Although no professional athletes have been
done, to our knowledge, we feel that this implant could
withstand the impact and repetitive stresses of a professional football player.
The treatment focus of Berlet et al10 is similar to
that of HemiCAP implantation by targeting metatarsal
head pathology. In both techniques, preliminary results
demonstrate similar postoperative range of motion, pain
relief, and patient satisfaction while avoiding postoperative deformities, transfer metatarsalgia, or push-off
weakness. It seems that addressing the metatarsal surface may provide better results when treating hallux
rigidus. Although it should be remembered that both
techniques have only preliminary results, and longer follow-up is needed to determine the durability of each
treatment option.
The HemiCAP technique is minimally invasive, with
only subchondral bone resection needed for its implantation. Viable bone stock is therefore preserved, and future
treatment options including joint fusion are maintained
should the condition require further intervention.
In summary, the use of the HemiCAP implant to resurface the metatarsal head in hallux rigidus has shown
very promising short-term results. Longer follow-up is
needed to determine the durability of this implant and
long-term functional outcomes. Future studies to determine the optimal technique for addressing coexisting
phalangeal involvement are also needed.
| REFERENCES
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2. Gianini S, Ceccarelli F, Faldini C, et al. What’s new in
surgical options for hallux rigidus? J Bone Joint Surg Am.
2004;86A:72Y83.
3. Mann RA, Clanton TO. Hallux rigidus: treatment by
cheilectomy. J Bone Joint Surg Am. 1988;70A:400Y406.
4. Mulier T, Steenwerckx A, Thienpont E, et al. Results after
cheilectomy in athletes with hallux rigidus. Foot Ankle Int.
1999;20:232Y237.
5. Moberg E. A simple operation for hallux rigidus. Clin
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