Home Research PapersPainful intermetatarsal angle (IMA) with a smaller, less prominent

Painful intermetatarsal angle (IMA) with a smaller, less prominent

Painful juvenile hallux
abducto valgus (HAV) is initially treated conservatively. Whether it be
altering shoe gear, using orthotics or incorporating other modifications, conservative
treatment options are usually exhausted before the consideration of more
invasive procedures. If symptoms persist, surgical intervention options can be
explored. A major concern for operating on young patients is the possibility of
recurrence of the HAV deformity due to the progressive nature of this
condition. Though there are common surgeries performed currently, exploring
other techniques may prove to be beneficial, especially when preoperatively
taking care to plan for adequate correction of the deformity and prevent
recurrence, while aiming to completely relieve the pain.

Introduction

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Hallux valgus was first
introduced by Carl Heuter in 1871, who described lateral angulation of the
first metatarsophalangeal joint, associated with lateral deviation of the
sesamoids.22 Juvenile HAV deformity has several interchangeable
names commonly used, such as, juvenile or adolescent bunion, hallux valgus and
metatarsus primus adductus.6 Juvenile HAV is often bilateral and is
more prevalent in females affecting 22-26% of adolescents.8, 15
However, it is seldom the cause of pain, when compared to adult HAV.19

Compared to adults,
juvenile HAV commonly has a larger intermetatarsal angle (IMA) with a smaller,
less prominent medial eminence. Often, juvenile patients with an HAV deformity
can also present with other conditions such as metatarsus adductus, pes planus
and equinus. If present, these deformities must also be addressed.21
Banks et al found that 66.7% of cases reviewed, demonstrated that patients with
juvenile HAV had a metatarsus adductus angle of greater than 15 degrees.  Many
studies have shown a high incidence of recurrence after surgical intervention,
which is believed to be due to inadequate correction of the IMA.21

Generally, conservative
therapy is the initial treatment option for juvenile HAV. These include
modified shoe gear with a wider toe box, splinting, and toe wedges.17, 20
Occasionally, orthotics may be helpful in certain situations if the deformity
is biomechanical in etiology, and if the deformity is not severe nor
significantly painful.14, 20 However, these treatment options only
serve to treat the symptoms, while further progression of the deformity is
inevitable.23 If conservative treatment options fail, surgical
intervention should be considered as the next line of treatment, especially if
the deformity is severe and painful.

Surgical options need to
be thoroughly explored in order to prevent recurrence and avoid the need for additional
surgery.10 Popular procedures include the chevron or double first
metatarsal osteotomy for HAV in children, however, other techniques should be
considered based on the deformity and pathogenesis to prevent recurrence.4,
13 Though there is no optimal age or accepted criteria for surgical
treatment in juvenile HAV deformity as each case differs, the following modified
procedures may bring light to different techniques that could possibly achieve
better results.18

Surgical intervention of
juvenile HAV is not commonly favorable due to the high recurrence rate of
30-40%.1 When considering surgical correction of juvenile HAV, care
must be taken to consider the etiology of the deformity, the timing of the
surgery in regard to bone growth, and the severity of the deformity.1, 6
Generally, mild or moderate deformities can be corrected with a distal
osteotomy of the first metatarsal, while more severe deformities may require a
base osteotomy for greater correction. Surgical technique generally depends on
the severity of the deformity, and thus surgical planning of procedures must
carefully be considered.

Radiographic findings

The IMA can be measured
by the intersection of the longitudinal axis of the first metatarsal with the longitudinal
axis of the adjacent metatarsal. An angle of 10 degrees or greater is often
indicative of pathology.19 A hallux valgus angle of greater than 16
degrees is also indicative of pathology. This angle can be measured by the
intersection of the long axis of the proximal phalanx with the long axis of the
first metatarsal. Lateral displacement of the sesamoids is often correlated
with the severity of a hallux valgus deformity. Any degree of hallux valgus
deformity will rotate the sesamoids along the long axis of the metatarsal,
altering their position.19 The proximal articular set angle (PASA) can
also be measured to assess the relationship between the long axis of the first
metatarsal with the articular surface of the hallux.5 Together,
these angles are useful in determining the severity of a hallux valgus
deformity.

Scarf-Akin osteotomy

Agrawal et. al describes
a procedure in which a Scarf osteotomy is combined with an Akin osteotomy in
the treatment of juvenile HAV. The Scarf procedure is a tricut osteotomy that
is used to correct moderate to severe deformities, correcting an abnormal IMA, an
abnormal PASA, and an abnormal hallux interphalangeus angle, especially when
combined with an Akin osteotomy. A Scarf osteotomy allows for considerable
translation of the metatarsal without any shortening of the first ray, and in
turn, allows for significant correction. Adding an Akin osteotomy, a closing
wedge osteotomy of the proximal phalanx, further corrects any additional
abnormalities. An Akin osteotomy is generally performed to correct an abnormal
articular set angle.25 When paired with a Scarf osteotomy, these two
procedures prove to be powerful in providing the greatest correction.1

Of the 47 feet reported
by Agrawal et al who underwent Scarf-Akin osteotomies for moderate to severe HAV,
only 14 feet reported a recurrence of hallux valgus. Agrawal et al observed a recurrence
rate of 29.8%, with 21.3% of patients symptomatic enough to require surgical
revision. The reasons for recurrence were unclear, and may be due to the
patient’s young age or to a more marked deformity. Together, the Scarf and Akin
osteotomies are strong surgical procedures when considered for the management
of HAV. However, the high recurrence rate of 29.6% should be considered and
surgical intervention utilizing this method should be reserved for adolescent
patients with a significantly painful and severe HAV deformity.1

Percutaneous Osteotomy

Gicquel et al
retrospectively reviewed 33 percutaneous hallux valgus procedures in female
patients at an average age of 12.5 years.  The IM and distal metatarsal
articular (DMAA) angles were measured on weight-bearing radiographs to
determine the hallux valgus angle (HVA). Abnormal values were as follows: IMA
greater than 10 degrees, DMAA greater than 8 degrees and HVA greater than 15. A
Reverdin-Isham distal metatarsal osteotomy was used in combination with a
bunionectomy (only if the first metatarsal head was prominent), release of the
first metatarsophalangeal joint and a wedge osteotomy of the proximal first
phalanx. In patients with an IMA greater than 18 degrees, they performed a
lateral wedge osteotomy at the base of the first metatarsal.12

            In
place of internal fixation, a bandage was used to hold the first ray in an overcorrected
position for six weeks postoperatively, followed by a toe spacer for six
months. Averages for the preoperative IMA, DMAA and HVA were 13.61, 15.97 and
28.6 degrees, respectively. Postoperative averages of IMA, DMAA and HVA were
12.74, 8.97 and 19.45 degrees, respectively. Of the 33 cases, 20 had a postoperative
HVA greater than 16 degrees and after 31.5 months, all 20 cases demonstrated under
correction. Having a high preoperative IMA and insufficient DMAA correction
were risk factors correlated with under correction. The results from the
percutaneous osteotomy showed under correction which was inversely related to a
high-rated patient satisfaction. Since this study had a relatively small sample
size, and a short-term follow-up, there is not sufficient data to determine
whether the procedure could be effective amongst a larger population.12

            Crespo
Romero and colleagues performed a percutaneous forefoot surgery (PFS) on 108
patients having a recurrence of medial first metatarsal head pain in 22 cases.
Though their patients had a low postoperative pain level, their results showed
insufficient HVA correction, as well.9

Proximal Abduction-Supination Osteotomy

In 2013, Okuda et al
published a preliminary report on a technique combining a proximal
abduction-supination osteotomy of the first metatarsal with a distal
soft-tissue procedure for the surgical treatment of adolescent hallux valgus. A
total of 11 symptomatic female patients (12 feet) underwent the procedure. The
average age at the time of surgery was 17 years old. The surgical technique
consisted of a few steps after initially releasing the distal soft tissues. The
medial eminence was minimally excised to preserve the distal articular surface
of the first metatarsal head. The adductor hallucis tendon was then dissected from
its insertion site, while also releasing the transverse metatarsal ligament. At
1.5 cm distal to the metatarsocuneiform joint, a proximal crescentic osteotomy
was performed on the first metatarsal.22

Once the proximal
fragment was moved medially, the distal fragment of the first metatarsal was
abducted, and then manually supinated. Once the desired correction was achieved,
1.5 mm Kirschner wires were used to stabilize and secure the osteotomy site.
This technique reduced the hallux valgus angle to less than or equal to 17
degrees, and the IMA to less than 10 degrees. The preoperative hallux valgus
and IMA averaged 32.3 and 14 degrees, respectively.22

In this study, Okuda et
al used the Japanese Society for Surgery of the Foot (JSSF) standard rating
system which incorporates pain, function and alignment to a numerical value of
100 points maximum. Preoperatively the JSSF score was 62.0 points and
postoperatively the score increased to 99.2 points. All patients were pleased
with their results postoperatively and there were no recurrences of hallux
valgus.22

Surgical techniques for HAV
in juveniles tends to steer clear of the proximal aspect of the first
metatarsal in order to avoid the growth plate, which may be why there have been
more literature on the distal metatarsal osteotomies.24, 26 Though
this study advocates for more proximal osteotomies in adolescents, one caveat
is all the patients had closed first metatarsal epiphyses and were therefore
skeletally mature for this type of procedure. Depending on the age of the
patient, this procedure may not be an option for the adolescent with painful hallux
valgus.22

Conclusion

            Treating
a juvenile hallux abducto valgus deformity is challenging. Considerations such
as the growth plate at the first metatarsal base and allowing the young and
active adolescent to weight bear needs to be taken into account when choosing
an appropriate procedure.11, 16
Though there is no criteria when deciding a particular procedure and
no single technique to address all HAV deformities, modifications of previously
documented osteotomies can benefit the growing patient.27 The
purpose of analyzing the Scarf and Akin osteotomies, percutaneous osteotomy,
and proximal abduction-supination osteotomy are in hopes of further advancement
of modified osteotomies in juvenile bunions.

Surgical treatment for
hallux abducto valgus deformity in juveniles are typically avoided when
possible due to the limited number of studies. In skeletally immature patients,
the risk of recurrence after surgery appears to be higher.2 Many
studies recommend waiting until the patient has reached skeletal maturity
before proceeding with surgical intervention due to the high recurrence rate,
related to the presence of an open metaphysis.7, 11

Acknowledgements

            We
gratefully acknowledge the support of Dr. Thomas Merrill at Barry University
School of Podiatric Medicine for mentoring and inspiring this literature
review. 

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