Keywords
foot deformities - orthopedic procedures - osteogenesis, distraction - metatarsal
bones
Introduction
Brachymetatarsia is a rare congenital deformity, predominant in females (92.5%),[1] in which the metatarsus of the foot is shortened by ≥ 5 mm in relation to the transverse
arch of the foot. [2] It mainly affects the fourth metatarsal, but the pathology can occur in any metatarsal
bone. In addition to aesthetic insecurity, the deformity can impair the support mechanism
of the foot, causing pain to walk. Surgical treatment is an alternative in the search
for a satisfactory aesthetic and functional result.[3]
[4]
The etiology of the pathology is not yet fully understood. The main cause is premature
closure of the metatarsal growth plate, resulting from hereditary, post-traumatic
or postsurgical factors.[5] It may be associated with diseases such as Down syndrome, Apert syndrome, Albright
osteoarthritis, sickle cell anemia, diastrophic anomaly, poliomyelitis, endocrinopathies,
and Turner syndrome.[1] Other secondary causes described in the literature include infections, tumors, and
radiation exposure.[6]
Brachymetatarsia is typically detected between 1 and 5 years of age, may affect ≥
1 metatarsi, and may be unilateral or bilateral. The incidence of bilateralism occurs
in > 50% of the cases described in the literature.[7] The complaints of the patients include metatarsalgia, calluses, irritation in the
use of footwear, and soft tissue contractures. However, aesthetic appearance is the
main complaint in young women, resulting from the shortening of the affected radius
or associated deformities of the other toes, including the deviation of normal rays
to fill the gap formed by the compromised metatarsus, generating varsity deformities
in the medially located and varus fingers in the laterally located fingers.[8]
Surgical treatment of brachymetatarsia includes techniques that use acute stretching
using interpositional bone graft or gradual stretching by osteogenic distraction (with
or without graft), associated or not with a procedure in adjacent phalanges.[5]
[9]
[10] Distraction osteogenesis using external fasteners is a widely used technique, especially
when stretching > 1 cm is required.[11] Although the long duration of treatment and the understanding and cooperation of
the patient may seem unfavorable in the choice of this technique,[8] some important advantages of the use of gradual distraction include increased construction
stability, possibilities of longer stretching, greater control of stretching, shorter
surgical time, and absence of the need for bone graft (which can generate pain and
discomfort in the donor area, in addition to the risk of graft absorption).[1]
The aim of the present study was to describe the profile of the patients and the results
obtained with the use of external fixator for metatarsal stretching in brachymetatarsia
in an orthopedics and traumatology service.
Material and Methods
The present retrospective study with analysis of medical records was approved by the
Research Ethics Committee of the proposing institution with the CAEE number 34810920.2.0000.0033.
The collected data were evaluated in Microsoft Excel 2007 (Microsoft Corporation,
Redmond, WA, USA) and in SPSS Statistics for Windows version 17.0 (SPSS Inc., Chicago,
IL, USA).The present study included 6 patients diagnosed with brachymetatarsia treated
between January 2018 and April 2020 and a total of 8 feet and 12 metatarsi.
The following epidemiological variables were evaluated: age, gender, reason for consultation
(aesthetic deformity, metatarsalgia, difficulty to put on shoes), affected side, affected
metatarsal, presence of pain or callosity (before and after surgery), time of distraction
of the fixator, stretching obtained (in mm), time of use of fixator, complications,
and postsurgical satisfaction.
Radiographs ([Figure 1]) were used in the anteroposterior and profile incidences for evaluation of the parameters
of stretching (length gain) and of the callogenesis of bone regenerated. The desired
clinical aspect in the correction of the deformity determined the stretching period
to be performed by the patient via outpatient care.
Fig. 1 Radiograph in anteroposterior incidence of the feet with load demonstrating the evolution
of a patient with bilateral brachymetatarsia in the 3rd and 4th metatarsi submitted to osteogenic distraction. (A) preoperative radiography, (B)
postoperative radiography of the right side, (C) postoperative radiography of the
left side; and (D) result after 12 weeks of treatment.
The inclusion criteria were patients submitted to osteogenic distraction with external
fixator for metatarsal elongation in brachymetatarsia. Participants who underwent
any surgical procedure for metatarsal stretching other than osteogenic distraction
with monolateral external fixator were excluded from the sample.
The surgical technique used followed the following standardization: patient in the
supine position with a lateral inclination of 45° on the side to be operated, using
a pneumatic garrote inflated at 300 mmHg. Under fluoroscopy guidance, two Schanz pins
are inserted into the proximal mephemis and two in the distal mephemis. The pins are
positioned in an inclination of 45° in relation to the axis of the metatarsus to be
elongated, after skin incision with scalpel, blade number 15, dissection of soft parts
with delicate hemostatic clam for the removal of tendons, and broaling with punch
with rotational control. When the metatarsal to be lengthened is very shortened, the
placement of a pin on the corresponding cuneiform bone is accepted. After installation
and locking of the two heads of the minifixator, a skin incision is made with dissection
by planes, diaphysis exposure, and multiple perforations with a delicate drill to
aid in corticotomy. Corticotomy is performed with delicate osteotomy, direct subvisualization,
and fluoroscopy was conferenced intraoperatively. Next, the metatarsus-phalange joint
is fixated with a Kirschner wire 1.5 ([Figure 2]) to avoid deformity in phalanx flexion during distraction stretching. After that,
the skin incision is closed at the site of corticotomy with nylon 4.0 thread and bandages
on the pins. When there it is necessary to place more than one external fixator, the
procedure is performed in the same way by carefully observing the distance between
the assemblies so as not to hinder distraction and stretching.
Fig. 2 Monolateral external fixator installed for bone distraction at 45° inclination and
intramedullary Kirschnner wires.
The patients in the present study were discharged from the hospital in 48 hours. They
were instructed on when to start and on how to perform bone distraction, 0.25mm every
12 hours, with weekly radiographs and partial load with rigid sole. The removal of
the external fixator was performed in all patients in the 12th postoperative week, under sedation.
Results
In the period from 2018 to 2020, 6 patients were surgically treated, totaling 8 feet
and 13 metatarsi ([Table 1]) submitted to osteogenic distraction with external fixator. The mean age was 28
years old ( ± 14.62; 95% confidence interval [CI]: 16.31–39.69), ranging from 15 to
48 years old. All patients (100%; n = 06) were female, with congenital brachymetatarsia and motivated to seek orthopedic
service due to aesthetic deformity. Only one patient complained of presurgical pain.
Table 1
|
Data
|
Values
|
|
Number of participants (n)
|
6
|
|
Number of metatarsi (n)
|
13
|
|
Number of feet (n)
|
8
|
|
Female (n)
|
6
|
|
Age ( ± standard deviation)
|
28 ± 14.62 years old
|
|
Laterality (n)
|
−
|
|
Bilateral
|
2 patients
|
|
Right
|
2 patients
|
|
Left
|
2 patients
|
|
Patients with aesthetic dissatisfaction
|
6 (100%)
|
The involvement was bilateral in two patients and unilateral in four patients. The
mean stretching time was 22 days ( ± 7.15; 95%CI: 19.04–26.81) and the total mean
length of elongation was 11.46 mm ( ± 3.57; 95%CI: 9.52–13.40); the mean was higher
in the right foot (25.43 ± 9.07 days) than in the left (20.00 ± 2.19 days; p < 0.05). Regardless of the affected side, the frequency of deformity is higher in
the fourth metatarsus, in which all patients had deformity ([Figure 3]).
Fig. 3 Frequency of brachymetatarsia according to the side and metatarsus affected in patients
using a monolateral external fixator for stretching.
[Table 2] shows the individual data referring to the stretching time (in days), the length
obtained (in mm), and the follow-up time (in months) of the patients treated using
an external fixator separated according to the affected side and metatarsus. The metatarsi
on the right side presented the highest means of stretching time and length obtained.
For the fourth metatarsi on the right side, the elongation lasted on average 28.76
days, and the average length obtained was 14.33 mm. For the fourth metatarsus on the
left side, the mean was 22 days, and the length was 11 mm. The third metatarsus followed
the same trend, with a mean elongation time on the right side of 24.67 days and an
average length of 12.33 mm, which were higher than those of the left side, of 18 days
and 9 mm. The stretching speed was 0.5 mm/day and the patients were instructed to
lengthen the fixator daily. The mean follow-up period was 18 months, ranging from
6 to 48 months.
Table 2
|
Side
|
Right
|
Left
|
FT
(months)
|
|
Metatarsus*
|
Third
|
Room
|
Third
|
Room
|
|
Patient
|
T (days)
|
L (mm)
|
T (days)
|
L (mm)
|
T (days)
|
L (mm)
|
T (days)
|
L (mm)
|
|
1
|
−
|
−
|
−
|
−
|
−
|
−
|
20
|
10
|
24
|
|
2
|
−
|
−
|
18
|
9
|
−
|
−
|
−
|
−
|
48
|
|
3
|
−
|
−
|
−
|
−
|
−
|
−
|
20
|
10
|
12
|
|
4
|
18
|
9
|
20
|
10
|
18
|
9
|
20
|
10
|
8
|
|
5
|
20
|
10
|
26
|
13
|
18
|
9
|
24
|
12
|
12
|
|
6
|
36
|
18
|
40
|
20
|
−
|
−
|
−
|
−
|
6
|
|
Average ± SD
|
24.67 ± 9.87
|
12.33 ± 4.93
|
28.67 ± 9.93
|
14.33 ± 4.97
|
18.00 ± 0.00
|
9.00 ± 0.00
|
22.00 ± 2.00
|
11.00 ± 1.00
|
18.3 ± 15.8
|
According to the data from the medical records, 50% (n = 03) of the patients had local infection of the pins and were treated with antibiotics;
the others did not report any postsurgical complications. All patients denied pain
or callosity after the surgical procedure and reported being satisfied with the results
obtained.
Discussion
The main complaint of patients seeking treatment for brachymetatarsia is associated
with aesthetic deformity or functional difficulty.[2]
[6] These patients are generally excluded from social and sports activities due to the
appearance of the foot.[12] In the present study, aesthetic appearance was the main complaint reported by patients
undergoing surgical treatment. About 25% of primary weight support stress is absorbed
by the metatarsi. The shortening of any of them leads to overload and laxity of the
transverse ligament, causing inadequate forefoot contact, excessive pressure, and
impaired muscle function, resulting in pain and fatigue in the leg and the foot.[13] Pain is considered the second most common indication for the surgical treatment
of brachymetatarsia.[14] None of the patients in the present study reported significant pain complaints.
Most of the cases described in the literature[3]
[4]
[8]
[9] and all cases evaluated in the present study are female. Brachymetatarsia is a rare
congenital deformity (its incidence in the population ranges from 0.02 to 0.05%),
with a higher frequency in females, at the ratio of 25:1 when compared with males.[12]
The greatest demand for surgical treatment of brachymetatarsia occurs in the adolescence,
due to aesthetic dissatisfaction.[2] However, in the present study, half of the sample was composed of adolescents and
the other half was of young adults (50%; n = 3). The mean age of the operated patients was 28 years old, close to that observed
by Giannini et al.[8] (mean of 27 years old, ranging from 12 to 42 years old) when evaluating 29 patients
operated for correction of brachymetatarsia in an Italian hospital for 10 years. These
same authors[8] suggest that surgery be performed after 12 years of age, as bone growth should be
expected to be completed, in addition to the difficulty of management after surgery
in younger children. Lee et al.[15] report a lower rate of complications in operated adolescents when compared with
adults in relation to bone regenerated consolidation.
Lamm[11] suggests that for a gain of 20 mm in metatarsal elongation, the time required would
be ∼ 45 days, with 5 days of latency and 40 days of distraction at a speed of 0.5 mm/day.
In the present study, the distraction speed was 0.5 mm/day (0.25 mm every 12 hours)
and the mean elongation time was 22 days. Stretching speeds > 1 mm/day may result
in pain, in excessive soft tissue tension, and in joint dislocation[16] Gradual stretching in a single stage reduces the risk of neurovascular involvement,
as it generates lower soft tissue tension. When the need for stretching is > 10 mm,
the risk of neurovascular involvement is the main limitation of acute treatment with
stretching, bone grafting, and internal fixation.[11]
When evaluating 48 cases of brachymetatarsia, Peña-Martínez et al.[16] observed that the fourth metatarsus was the most affected, representing 98% of the
cases, with the third metatarsus representing the other 2%. In the present study,
61.5% (n = 8) of the deformities were in the fourth metatarsus, and 38.5% (n = 5) were in the third metatarsus ([Figure 3]). The chosen technique used a monolateral external fixator associated with the use
of Kirschner wires ([Figures 2] and [4]), promoting stability in the metatarsophalangeal joint and avoiding deformity in
metatarsus flexion during bone stretching.
Fig. 4 Postoperative of a patient with a 3rd and 4th metatarsi deformity of the left foot submitted to bone stretching with monolateral
external fixator.
Osteogenic distraction is the most accepted and most successful treatment performed
by foot and ankle surgeons for metatarsus stretching.[17] The advantages of gradual stretching are the ability to obtain a longer length compared
with that obtained by the use of an interim bone graft, allowing immediate weight
support and preserving the movement of the metatarsal-phalangic joint, and the fact
that it does not present the need for bone graft, which can generate discomfort in
the donor area.[11] These advantages make the technique of gradual distraction the most used method
when seeking a stretching > 15 mm or > 25% of the initial size of the metatarsus.[1]
Osteogenic distraction has as a disadvantage the need for regular adjustment of the
external fixator for stretching, the possibility of insufficient bone formation, and
the risk of local infection. To stimulate adequate bone formation, a careful osteotomy
should be performed with minimal damage to soft tissue and vascular tissue.[11]
[18]
In stretching by osteogenic distraction in 2 stages, distraction is performed more
quickly (∼ 2 mm per day), and after reaching the desired length, the placement of
bone graft in the regenerated and the replacement of external fixation by the internal
fixation, in the absence of infection of the pins, are performed to reduce the time
of the external fixator and joint stiffness.[14]
Masada et al.[19] report a higher number of postoperative complications when stretching is > 40% of
the original length of the metatarsus, citing excessive stretching, joint stiffness,
loss of alignment, delayed consolidation, and fracture of the regenerated.
In all analyzed patients, the elongation achieved was obtained without loosening the
pins, with a good bone regenerated without the need for graft use in a second moment
or for another surgical procedure in addition to the removal of the external fixator
and of the Kirschner wire via outpatient care. Consolidation was obtained in 100%
of the patients within the period of 8 to 12 weeks. At the end of the treatment, all
patients presented good surgical correction, good aesthetic aspect ([Figure 5]), high degree of satisfaction with the surgery, and no degree of stiffness or of
mobility deficit in the joints of the third and fourth toes.
Fig. 5 Preoperative (A) and postoperative (B) clinical aspects of a patient with bilateral
brachymetatarsia in the 3rd and 4th metatarsi submitted to osteogenic distraction using a monolateral fixator.
In the scientific literature, it is well-established that external fixation restores
the length of the metatarsus, the position of the toes, the function of the foot and
toes, improves cosmesis, and reduces pain.[20] The results obtained in the present study were comparable to those of other studies
in terms of demographic characteristics, amount of surgical correction, and clinical
results.[9]
[20]
[21] The present study also presents some limitations due to its retrospective nature,
besides having a relatively small sample and a short follow-up time in the postoperative
period.
Conclusion
All patients were female and sought surgery for brachymetatarsia for aesthetic reasons.
Gradual osteogenic distraction at a rate of 0.5 mm/day using an external fixator and
fixation of the metatarsophary joint with Kirschner wire resulted in successful stretching
of the metatarsus, with good aesthetic and functional results. Despite the limitations
of the present study, the good clinical results and the high satisfaction of the patients
make the use of a monolateral external fixator for metatarsus elongation in brachymetatarsia
a good option.
