Ninety-degree chevron osteotomy for correction of hallux valgus deformity: clinical data and finite element analysis.
ABSTRACT Hallux valgus is a very common foot disorder, with its prevalence estimated at 33% in adult shoe-wearing populations. Conservative management is the initial treatment of choice for this condition, but surgery is sometimes needed. The 60(0) angle Chevron osteotomy is an accepted method for correction of mild to moderate hallux valgus in adults less than 60 years old. A modified 90(0) angle Chevron osteotomy has also been described; this modified technique can confer some advantages compared to the 60(0) angle method, and reported results are good. In the current work we present clinical data from a cohort of fifty-one female patients who had surgery for sixty-two hallux valgus deformities. In addition, in order to get a better physical insight and study the mechanical stresses along the two osteotomies, Finite Element Analysis (FEA) was also conducted. FEA indicated enhanced mechanical bonding with the modified 90(0) Chevron osteotomy, because the compressive stresses that keep the two bone parts together are stronger, and the shearing stresses that tend to slide the two bone parts apart are weaker, compared to the typical 60(0) technique. Follow-up data on our patient cohort show good or excellent long-term clinical results with the modified 90(0) angle technique. These results are consistent with the FEA-based hypothesis that a 90(0) Chevron osteotomy confers certain mechanical advantages compared to the typical 60(0) procedure.
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ABSTRACT: We report a prospective study of seven patients (eight feet) who underwent a soft tissue correction of hallux valgus using a web approach. All were female patients with an average of 50 years (range, 17–77 years). The average duration of follow-up was 20 months (range, 6–28 months). The metatarso-phalangeal angle was corrected by an average of 9.5° and the intermetatarsal angle by an average of 2° after the procedure. No patient complained of pain or joint stiffness after surgery and all of them could wear normal footwear. All patients thought cosmesis was good. The overall subjective assessment was excellent in seven and good in one case. We recommend first webplasty as a simple and effective procedure in moderate cases of hallux valgus.The Foot 01/2004; 14(2):92-95.
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ABSTRACT: Seventy-six chevron osteotomies with follow-up periods ranging from six months to eight years were reviewed. The majority of patients had pain over the bunion prior to operation, and 27 also presented with second metatarsalgia. After surgery there was a marked decrease of pain in the first metatarsophalangeal joint, and in 18 feet the second metatarsalgia was either eliminated or markedly decreased. Most patients were pleased with the appearance of the feet after surgery, but almost one-third of the women complained of difficulty in wearing high heels. The surgical technique is straightforward, but careful attention to detail is necessary to obtain a consistent and satisfactory result.Clinical Orthopaedics and Related Research 04/1984; · 2.79 Impact Factor
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ABSTRACT: The purpose of this study was to compare the results of the Chevron osteotomy to the DuVries' modification of the McBride procedure using identical criteria in two groups of patients. Thirty-two patients (48 feet) that had a Chevron osteotomy and 10 patients (17 feet) who had a modified McBride bunionectomy without metatarsal osteotomy for treatment of mild to moderate hallux valgus were retrospectively reviewed using subjective and objective criteria. Both groups were matched according to age, severity of deformity, and length of follow-up. Ninety-two percent of patients in the Chevron group and 88% of patients in the McBride group responded that they were either totally satisfied or improved regarding pain relief and appearance of the foot following surgery. Chevron osteotomy resulted in a statistically significant greater correction of the intermetatarsal 1-2 angle than did the McBride bunionectomy. Postoperative metatarsophalangeal joint range of motion was not significantly different for the two groups. Following Chevron osteotomy, five (10%) metatarsal heads exhibited radiographic changes of cyst formation and/or increased osteodensity and three (6%) of the osteotomies healed in a malunited position. One of the three metatarsal head malunions occurred in a patient that also had a lateral capsular release, however, none of the five cases that developed radiographic changes in the first metatarsal head was associated with a lateral capsular release. Lateral capsular release with the Chevron osteotomy did not improve the amount of correction of the hallux valgus deformity and it may be a contributing factor to instability at the osteotomy site leading to a valgus malunion.Foot & ankle 11/1991; 12(2):61-8.
152 The Open Orthopaedics Journal, 2010, 4, 152-156
1874-3250/10 2010 Bentham Open
Ninety-Degree Chevron Osteotomy for Correction of Hallux Valgus
Deformity: Clinical Data and Finite Element Analysis
Charalambos Matzaroglou1, Panagiotis Bougas1, Elias Panagiotopoulos1, Alkis Saridis1,
Menelaos Karanikolas*,2 and Dimitris Kouzoudis3
1Department of Orthopaedic Surgery, University of Patras, Greece
2Department of Anaesthesiology and Critical Care, University of Patras, Greece
3Engineering Sciences Department, University of Patras, Greece
Abstract: Hallux valgus is a very common foot disorder, with its prevalence estimated at 33% in adult shoe-wearing
populations. Conservative management is the initial treatment of choice for this condition, but surgery is sometimes
needed. The 600 angle Chevron osteotomy is an accepted method for correction of mild to moderate hallux valgus in
adults less than 60 years old. A modified 900 angle Chevron osteotomy has also been described; this modified technique
can confer some advantages compared to the 600 angle method, and reported results are good. In the current work we
present clinical data from a cohort of fifty-one female patients who had surgery for sixty-two hallux valgus deformities. In
addition, in order to get a better physical insight and study the mechanical stresses along the two osteotomies, Finite
Element Analysis (FEA) was also conducted. FEA indicated enhanced mechanical bonding with the modified 900
Chevron osteotomy, because the compressive stresses that keep the two bone parts together are stronger, and the shearing
stresses that tend to slide the two bone parts apart are weaker, compared to the typical 600 technique. Follow-up data on
our patient cohort show good or excellent long-term clinical results with the modified 900 angle technique. These results
are consistent with the FEA-based hypothesis that a 900 Chevron osteotomy confers certain mechanical advantages
compared to the typical 600 procedure.
Keywords: Osteotomy, hallux valgus, finite element analysis.
in civilized populations , with an estimated 33% of adults
in shoe-wearing populations having some degree of this
condition . Hallux valgus can be treated conservatively or
operatively, but the non-operative approach is considered as
the first-line option .
Hallux valgus is one of the most common foot disorders
for hallux valgus treatment . Distal metatarsal Chevron
osteotomy is indicated for correction of mild to moderate
hallux valgus (if the hallux valgus angle is less than 300 and
the intermetatarsal angle is less than 150 with a congruent
metatarsophalangeal joint). The typical Chevron osteotomy
(depicted as BCB’ in Fig. 1) has a simple 600 angle and is
very popular, because it provides stability, rapid healing and
minimal shortening with a low complication rate [4-10].
Even though this is a successful technique for hallux valgus,
more than a hundred versions of distal osteotomy have been
described ; the large number of proposed techniques
indicates that none of these techniques is entirely
satisfactory, and there is certainly room for improvement.
More than 150 surgical procedures have been described
that is often used for structural analysis of mechanical
*Address correspondence to this author at the Department of
Anaesthesiology and Critical Care, University of Patras, Rion, 26500,
Greece; Tel: +30-6977964148;
E-mails: firstname.lastname@example.org; email@example.com
Finite element analysis (FEA) is a computational tool
Fig. (1). Two dimensional side views of two Chevron osteotomies
applied at the metatarsal bone of the first ray in the human foot:
Points BCB’ depict the classic 600 osteotomy, whereas points
ACA’ depict the proposed 900 osteotomy. Point C indicates the
center of the circle circumscribed to the bone head.
systems . In recent years, FEA is increasingly used in the
biomedical sciences, with several applications of this
methodology recently published, especially in dentistry 
and in orthopaedic surgery [13, 14]. In the current work we
present clinical data and FEA results for a 900 Chevron
osteotomy (depicted as ACA’ in Fig. 1). FEA results predict
strong mechanical bonding for the 90o osteotomy, with
Modified Chevron Osteotomy for Hallux Valgus The Open Orthopaedics Journal, 2010, Volume 4 153
enhanced compressive stresses that keep the two bones
together, and reduced shearing stresses that tend to slide the
two bones apart, compared to the 60o method. As our clinical
data are very encouraging, and consistent with FEA results,
we hope this new technique will contribute to improved
patient comfort and quality of life.
MATERIALS AND METHODOLOGY
Patient Population and Procedure
fifty-one female patients with sixty-two hallux valgus
deformities, who had the modified 900 chevron osteotomy in
our institution between 1997 and 2003. As this is an
observational cohort study, there was no control group and
no blinding. The research protocol was approved by the
University of Patras Ethics Committee, and all patients gave
written informed consent before enrolling in the study. All
procedures were carried out by the same two orthopaedic
surgeons under general endotracheal anesthesia, and a
tourniquet was used in all cases. The procedure started with
a medial slightly curved longitudinal incision, followed by a
Y-shaped capsulotomy, and exposure of the medial
prominence. The exostosis was then removed, and all
patients had a modified 900 Chevron osteotomy (Fig. 2)
fixed with a Hebert screw. The capsule was closed and
placation of the medial capsule was performed. Any lesser
toe abnormalities were also corrected during the operation.
This was a prospective observational cohort study on
Fig. (2). Photograph taken during a 90o distal metatarsal osteotomy.
The actual 90o osteotomy looks like an “L” shape, as marked by the
arrows and circle.
mean length of follow-up was 32.7 months (range 24-54
months). On their last follow-up visit, patients were
interviewed and had clinical and radiologic evaluation,
including weight-bearing antero-posterior and lateral
radiographs, intermetatarsal angle (IMA) and hallux valgus
angle (HVA) measurement,
preoperative films. All patients were examined according to
the AOFAS Hallux Metatarsophalangeal-Interphalangeal
Scale . They were questioned about pain, function,
activity limitations, and footwear requirements and
Mean patient age was 54.9 years (range 17-70 years) and
and comparison with
examined to assess alignment, metatarsophalangeal joint
motion, interphalangeal joint motion and callus formation.
According to this scale, scores between 93 and 100 points
indicate an excellent result, 83 to 92 points indicate a good
result, 66 to 82 points indicate a fair result and scores less
than 65 points are evidence of a poor result.
Finite Element Analysis
consequences of the modified procedure and, hopefully,
predict clinical results, Finite Element Analysis (FEA) was
used to calculate the distribution of stresses on the first ray
of a human foot bone model. According to FEA a
mechanical model of a body is divided into numerous finite
geometrical elements; then the equations of the theory of
elasticity are applied to these elements. Due to the finite size
of these elements, the differential equations can be
approximated by equations of difference which can be
solved algebraically by numerical methods. In order to
improve consistency, we used two different standard FEA
software packages: ANSYS WorkbenchTM 10.0 (ANSYS,
Inc. Southpointe, 275 Technology Drive, Canonsburg, PA
15317, USA), which is a commercial software package, and
OOF2, which is an open-code freeware from the National
Institute of Standards and Technology (http://www.nist.gov/
index.html). The acronyms “ANSYS” and “OOF” are used
in this work when referring to these two packages
respectively. As shown in Fig. (3), a metatarsal bone model
was constructed by extruding the x-y profile of Fig. (1)
normal to the profile plane. This model is only a rough
approximation of the real bone, but it greatly simplifies
analysis and interpretation. This simplification is justified
because forces acting on the bone lie almost entirely in the
sagittal plane, and bone movement is restricted to this plane
only. Using a more realistic 3-D bone model would not add
significant correction to the 2-D model; consequently, we
chose to use the 2-D model, in order to reduce complexity
and time-consuming computation.
In an attempt to better understand the physical
Fig. (3). Forces on the metatarsal bone model used for Finite
Element Analysis. Values are calculated, based on Reference 6
(Jacob, Clin Biomed, 2001), assuming a body weight of 100 kg.
the 2001 Jacob study  where all the forces are expressed
in % body weight, which was set arbitrarily to 100 kg for
Anthropometric data and forces (Fig. 3) were taken from
154 The Open Orthopaedics Journal, 2010, Volume 4 Matzaroglou et al.
this analysis (forces on the joints had to be slightly rotated in
order to get equilibrium conditions). Table 1 contains the x-y
force components in Newtons. More specifically, F2 is the
external ground force, Fh equals Fhl + Fhb where Fhl and Fhb
are the forces acting along the tendons of the flexor hallucic
longus and flexor hallucic brevis muscles respectively; Fpl is
the xy-component of the peroneus longus force, and R4 and
R2 are equilibrium forces on the tarsometatarsal and
metatarsophalangeal joints from the neighboring bones. In
order to calculate the maximum stresses on the cuts, the bone
is drawn with a 350 angle to the floor (Fig. 1), which is the
angle the bone takes  during the push-off phase (second
force peak during stance).
Table 1. Forces (in Newtons) at the Metatarsal Bone Model
Presented in Fig. (3)
Symbol x-Value y-Value Origin
F2 0 290 External ground force
Fhl -475 221 Flexor hallucis longus muscle
Fhb -329 133 Flexor hallucis brevis muscle
Fpl -371 0 Peroneus longus force
R2 -62.1 145 Tarsometatarsal joint
1237 -789 Metatarsophalangeal joint
in total, with 8300 nodes on the xy plane, whereas the OOF
bone model was divided in 8000 elements with 8000 nodes
on the xy plane. Bone dimensions were 66 ? 37 ? 10mm and
bone volume was 12.8 cm3. The following bone material
constants were used : Elastic modulus 20 GPa, Poisson’s
ratio 0.3, density 1.94g/cm3 (average values). Calculated
bone mass was 24.3 g.
The ANSYS bone model was divided in 14000 elements
method were collected an average 32.7 months after the
operation (Table 2). Mean preoperative HVA was 34.1
degrees (range, 22 to 56 degrees) and mean preoperative
IMA was 15.5 degrees (range, 10 to 29 degrees). At the last
follow-up examination, mean postoperative HVA angle was
14.2 degrees (range, 0 to 28 degrees), mean postoperative
IMA angle was 8.1 degrees (range, 6 to 22 degrees), and
mean AOFAS score was 94.3 (range 67 to 100). Results
were rated as excellent in fifty feet (80.64%), good in 8 feet
(12.9%) and fair in 4 feet (6.45%). All osteotomies were
fused and there were no cases of non-union, loosening,
avascular metatarsal head necrosis or wound infection. Two
patients with fair results experienced late recurrence of the
deformity, but this was not clinically significant, and they
refused any further treatment.
Followup data from clinical application of this new
linear static structural FEA calculations and their outputs
consist of sets of stress vector components along specific
coordinate axes on each node of the model. Both data sets
can be found as supplementary info at the web links listed in
the Appendix [16, 17]. From these values, the average
Both software packages (ANSYS and OOF) performed
Table 2. Results of the Modified Chevron Osteotomy and
Herbert Screw Fixation at Follow-Up (Mean Follow-
Up Time 32.7 Months, Range 24-54 Months)
Age - yr* 54.9 (17-70)†
Female (%) 100
Hallux valgus angle (degrees) 14.2 (0-28)
Intermetatarsal angle (degrees) 8.1 (6-22)
AOFAS score (%)
*At time of operation.
†Numbers in parentheses indicate ranges.
normal and average shear stress was calculated on the nodes
of the 600 and the 900 osteotomies (Figs. 4, 5). In general,
normal compressive (positive) stresses along an interface
tend to keep the two parts together, while shear stresses tend
to slide the two parts apart. Therefore better bonding is
expected where the normal-to-shear stress ratio ? is positive
and greater than 1. Table 3 shows the average ? produced by
the two methods along the segments AC, CA’, BC and CB’
(Fig. 1) of the two osteotomies. For ease of comparison, all
ratios are normalized in the 0 to 1 range. In general, FEA
methods are complex and their results include some degree
of uncertainty; however, in the present work we only
attempted qualitative analysis, with no emphasis on detailed
numerical data. In this qualitative fashion, results obtained
with the ANSYS and OOF methods agree reasonably well.
In particular, both methods predict that the largest ? occurs
along the CA segment of the ACA’ (Fig. 1) osteotomy and it
is 2 to 3 times larger than the second largest ? which occurs
along the CB’ segment of the BCB’ osteotomy. Therefore a
stronger bonding is expected for the 900 ACA’ osteotomy
compared to the classical 600 Chevron osteotomy BCB’, and
this finding may explain our excellent clinical results.
However, the CA’ and the BC segments should also be taken
into account, and both methods predict low normal stresses
on these segments (Table 3). These interfaces will also
influence healing time, but we believe that the strong
bonding of the CA segment is the prevailing factor.
Our results indicate that the 900 angle may be a good
choice for Chevron osteotomy. Good clinical results have
been reported in 80-90% of patients having the typical 600
osteotomy [4, 6, 9] with recurrences or under-corrections
occurring in 10-14% of cases [5, 7, 8]. However, a recent
study by Torkki et al.  reported inferior results, probably
due to the number of different surgeons (including trainees)
who performed these operations and the unselected study
model seem to explain the good clinical results observed in
our patient cohort. These results are easier to explain
Data obtained from applying FEA analysis to a bone
Modified Chevron Osteotomy for Hallux Valgus The Open Orthopaedics Journal, 2010, Volume 4 155
Fig. (4). A plane x-y view of the bone model shown in Fig. (3),
with Finite Element Analysis nodes (tiny dots) created by the
ANSYS software while evaluating normal and shear stresses with
the 60o and 90o osteotomies. Due to the discrete nature of the
analysis, the two osteotomies cannot be represented by exact
straight segments. Filled triangles indicate the nodes chosen to
represent the 900 osteotomy, whereas filled circles indicate the
nodes chosen to represent the 600 osteotomy. Point C (arrow) is the
center of the circle shown in Fig. (1).
Fig. (5). A plane x-y view of the bone model shown in Fig. (3),
with Finite Element Analysis nodes (tiny dots) created by the OOF
software while evaluating normal and shear stresses with the 60o
and 90o osteotomies. Due to the discrete nature of the analysis, the
two osteotomies cannot be represented by exact straight segments.
Filled triangles indicate the nodes chosen to represent the 900
osteotomy, whereas filled circles indicate the nodes chosen to
represent the 600osteotomy. Point C (arrow) is the center of the
circle shown in Fig. (1).
Table 3. Normalized
Calculated by the Two FEA Packages for the Two
Osteotomies of Fig. (1)
Normal-to-Shear Stress Ratio
Section ANSYS OOF
AC 1.00 1.00
CA 0.20 0.08
BC 0.32 0.03
CB 0.35 0.47
physically if the bone is approximated by a straight long
beam under longitudinal compression. This is a well known
example in the theory of elasticity, with maximum and zero
normal stress along the directions of 00 and ± 900 with
respect to the beam axis, and maximum shear stress at ± 450.
In the case of the metatarsal bone, all forces in Fig. (3)
(except F2) are almost parallel to the long axis of the bone.
Because the metatarsal bone has an elongated shape, this
bone can be approximated by a beam, and this crude
approximation can help us understand the distribution of
stresses along the bone. As the ± 300 BCB’ osteotomy (Fig.
1) is close to the ± 450 case, a large shear stress is to be
expected. In contrast, as the AC and CA segments resemble
the 900 and 00 cases, normal stresses are expected to be
maximum and zero respectively.
degree Chevron osteotomy on a patient cohort of 51 women
who had surgery for 62 Hallux Valgus deformities, and we
also present results of Finite Element Analysis (FEA) of the
90o Chevron osteotomy. Compared to the 60o method, FEA
predicts enhanced mechanical bonding, with stronger
compressive stresses and weaker shearing stresses with the
900 Chevron osteotomy. Our good long-term clinical results,
together with results of Finite Element Analysis, suggest that
the 900 angle Chevron osteotomy is a good alternative to the
classic 60o method in patients with mild to moderate Hallux
Valgus who need surgery.
In this manuscript we present our experience with the 90-
collected data and drafted manuscript.
Charalambos Matzaroglou, performed many operations,
Panagiotis Bougas, assisted with most operations and
directed patient care and revised manuscript.
Elias Panagiotopoulos, supervised most operations,
and revised manuscript.
Alkis Saridis performed many operations, collected data
procedures, organized, revised and submitted manuscript.
Menelaos Karanikolas provided anesthesia for many
Element Analysis, and revised manuscript.
Dimitris Kouzoudis provided data, conducted Finite
CONFLICT OF INTEREST
All authors declare that they have no conflict of interest to
This work was supported solely by Department Funds.
University of Macedonia, Greece, for his invaluable
assistance on installing and configuring the OOF2 package
on a Linux system.
The authors would like to thank Vassilis Stefanidis,
sets of stress vector components along specific coordinate
axes which can be found at the web links
The outputs of two packages ANSYS and OOF consist of
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Received: December 7, 2009
Revised: December 21, 2009 Accepted: February 25, 2010
© Matzaroglou et al.; Licensee Bentham Open.
This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-
nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.