Resultados preliminares da correção de metatarso aduto associado a hálux valgo grave Preliminary results of the correction of metatarsus adductus associated with severe hallux valgus

Objective : Although hallux valgus is a common diagnosis and there are different well-described techniques for its correction, the presence of this deformity associated with a diagnosis of metatarsus adductus is relatively uncommon, and there is no consensus regarding surgical treatment. The objective of this study was to evaluate the preliminary radiographic results of angular corrections obtained in a series of cases of the surgical treatment of severe hallux valgus associated with adduction of the metatarsal bones, following the technique proposed herein. Methods : Retrospective data were collected from the medical records and pre- and postoperative radiographs of patients subjected to Lapidus arthrodesis combined with lateral rotation osteotomy at the bases of the second and third metatarsals. The following angular measurements were performed before and after surgery: hallux valgus angle, intermetatarsal angle, and the degree of adduction of metatarsal bones (measured by Sgarlato’s and Engel’s angles). The mean follow-up period was 18 months (16-24 months). Results: The mean hallux valgus correction angle was 31° (19-53°), and the mean intermetatarsal correction angle was 5.771° (2-9°). Regarding the forefoot adduction, the mean correction angle measured by the Sgarlato technique was 15.57° (12-21°) and by the Engel technique was 15.71° (10-22°). All of the measured angles decreased significantly in the postoperative assessment. Conclusion : Lapidus arthrodesis combined with rotational osteotomy at the bases of the second and third metatarsals proved to be effective for correcting the adduction of the metatarsals, allowing for the alignment of the first metatarsal and consequent correction of the deformity. Level of Evidence IV; Therapeutic Studies; Case Series.


INTRODUCTION
Hallux valgus is one of the most common foot deformities.The prevalence of this pathology is estimated at 23% among individuals aged 18 to 65 years and 35.7% among individuals over 65 years of age.The pathogenesis of hallux valgus deformity is complex, and surgical treatment plays a central role in its treatment, with more than 100 different surgical techniques having been described (1) .
Correction of the hallux valgus angle can be achieved through proximal, intermediate, and distal osteotomies of the first metatarsal, with lateralization of the distal fragment and consequent reduction of the hallux valgus angle and intermetatarsal angle (2) .
The presence of metatarsus adductus may be a risk factor for the development of hallux valgus (3) .A study conducted in 2014 analyzed 230 weight-bearing radiographs of the feet of patients diagnosed with hallux valgus and found a 35% incidence of metatarsus adductus.The data from that study suggest that patients with metatarsus adductus are 3.5 times more likely to develop hallux valgus (4) .
The identification of metatarsus adductus deformity is of great importance in the evaluation and surgical planning of hallux valgus.Adduction of the metatarsals is related both to the development of hallux valgus and to the postoperative recurrence of this deformity, especially when addressed alone (5,6,7) .
The presence of metatarsus adductus reduces the interval between the first and second metatarsals, a feature that can be verified by the low intermetatarsal angle, despite the severe hallux valgus.Thus, the area for the lateral displacement of the first metatarsal head is reduced, which precludes the surgical treatment of hallux valgus by traditional methods (6,8) .
Although hallux valgus is a common diagnosis and there are different well-described techniques for its correction, the presence of this deformity associated with a diagnosis of metatarsus adductus is relatively uncommon, and there is no consensus regarding surgical treatment in this case (7) .
The objective of this study was to evaluate the angular corrections obtained in a series of cases of severe hallux valgus associated with metatarsus adductus that were surgically treated through Lapidus arthrodesis combined with lateral rotation osteotomy at the bases of the second and third metatarsals, following the technique proposed herein.

METHODS
This study was approved by the Research Ethics Committee with registration in the Brazil Platform under CAAE number: 89703118.9.0000.5505.
The included data were collected from the medical records of patients who underwent surgical treatment of severe hallux valgus that was associated with metatarsus adductus by Lapidus arthrodesis combined with lateral rotation osteotomy at the bases of the second and third metatarsals between October 2016 and May 2017.
The full weight-bearing anteroposterior radiographs were taken of both feet simultaneously, with the X-ray beam centered between the feet in the first metatarsophalangeal joint and with a cephalic inclination of 10 to 15°.The radiographs were taken before and 3 months after surgery.

Materials:
The study included 7 patients who were operated on using the technique described below.All patients were female, with a mean age of 63.42 years (52-72 years).The sample comprised five right feet and two left feet.The first is represented by the axis of the 2nd metatarsus, while the midfoot axis is defined as the perpendicular line between the line connecting (c) the midpoint of the medial border (d) and the lateral border (e) of the midfoot.The medial border extends from the medial ends of the talonavicular joints to the first tarsometatarsal joint; the lateral border extends from the lateral ends of the calcaneocuboid joints to the cuboid (5th metatarsal) joints 8 .Source: author's personal archive.Table 1 shows the preoperative severity of the hallux valgus deformity according to the classification proposed by Mann (11) .Table 2 classifies the preoperative severity of the adduction of the metatarsals (11) as explained above.
Statistical analysis: Student's t-test for paired data was used to compare the preoperative angle values with those measured on the postoperative follow-up.A p-value <0.05 was considered statistically significant.The analyses were performed using SPSS 22.0.

Surgical technique
For the treatment of severe hallux valgus associated with metatarsus adductus, arthrodesis of the first tarsometatarsal joint (lapidus) associated with rotational osteo-tomy at the bases of the second and third metatarsals were performed according to the following steps: The surgery was performed under spinal anesthesia, starting with a lateral incision in the first interdigital space to release the sesamoid-metatarsal ligament and tenotomy Next, Lapidus arthrodesis was reduced so that the first metatarsal remained aligned with the medial cuneiform and was provisionally fixed with two 2.0-mm Kirschner wires.Due to this maneuver, the lateral rays rotated laterally.The Lapidus arthrodesis was fixed with two 3-mm cannulated screws and a 2.8-mm plate, and the lateral metatarsals were fixed with two 2-mm screws after fluoroscopic position confirmation.
After realignment of the metatarsals, we observed an imbalance of the parabola of the forefoot due to shortening of the first ray.Thus, Weil osteotomy was performed in the second and third metatarsals, with shortening and small lateral translation of the metatarsal head, in addition to release of the lateral collateral ligament to correct the abduction of the smaller toes.In 2 cases, the patients had irreducible deformities on the fourth toe, and thus, we performed the same procedure in this ray.The Weil osteotomy was fixed with one 2.0-mm screw.
In patients with alterations in the distal metatarsal articular angle (>6°), we performed biplanar chevron osteotomy to correct the deformity.In addition, patients with an altered interphalangeal angle (>14 o ) were corrected with Akin osteotomy.
In the postoperative period, the patients were immobilized with an orthotic boot and restricted from weightbearing on the operated limb for 6 weeks.The suture was removed 3 weeks after surgery, at which point motor physical therapy was started.Progressive partial weight-bearing was initiated on the 6th week, and the patient used the orthotic boot until the 8th week.
Patients were released to return to activities of daily living after being comfortable with the use of shoes with hard soles, around the 12th postoperative week.

RESULTS
The mean follow-up period was 18 months (16-24 months).The hallux valgus angle decreased on average by 31° (19-53°), decreasing from a mean of 42.9° before surgery to a mean of 12.9° after surgery.Using Student's t-test for paired data, we found that the mean valgus values in the postoperative period were significantly lower than the mean values in the preoperative period (p=0.001)(Table 3).
The intermetatarsal angle showed an average correction of 5.71° (2-9°), decreasing from a mean of 13.11° to 7.44° in the postoperative period.Using Student's t-test for paired data, we found a significant decrease in the values after surgery (p=0.001)..Source: Prepared by the author based on the results of the research.
of the adductor hallucis.We then initiated medial access at the height of the first metatarsophalangeal joint to perform capsular reconstruction and medial exostectomy.
The next step was the preparation for arthrodesis of the first tarsometatarsal joint.The joint was completely exposed, and the entire articular cartilage was removed.At this time, it was still not possible to correct the varus deformity of the first metatarsal because there was no space for lateral translation due to the adduction of the lateral metatarsals.
The metatarsals of the central column were approached through a dorsal incision between the bases of the second and third metatarsals.After bone exposure, osteotomy was performed with a sagittal saw under fluoroscopic guidance.We began the osteotomy 1cm distal to the midfoot joint with 45° inclination, in the proximal-to-distal and dorsalto-plantar directions, which made it possible to use screws perpendicular to the focus of the osteotomy for fixation.The main difficulty of this surgical step was to perform the osteotomy such that lateral rotation occurred without flexion or extension of the distal fragment.
Table 4 shows the angular correction obtained with the proposed treatment for the 7 cases included in the study.Figure 3 illustrates one of the cases, showing the weight-bearing radiographs taken of the patient before and after surgery.
The main postoperative complaints were diffuse swelling in the forefoot and difficulty moving the hallux and small toes in the first 6 weeks.No recurrence was diagnosed until the last assessment, and there have been no complications to date.

DISCUSSION
Although we found several studies on the prevalence and radiographic methods for evaluating hallux valgus associated with metatarsus adductus, there are few studies on the combined management of these pathologies.There is only one study available that proposes a protocol to be followed for the correction of both deformities (7) , but it is based on a series of only four cases.In that study, the authors present a surgical protocol similar to that used in our study, but Sharma and Aydogan added a calcaneal osteotomy as one of the initial steps of surgery.The results of the angular corrections were quite satisfactory in the previous study, as was also found in our investigation.
In addition to the severity of hallux valgus, several other factors should be considered for the surgical planning of hallux valgus associated with metatarsus adductus, such as the adduction angle of the metatarsals, deformities of the small toes, metatarsalgia, alteration of the distal metatarsal articular angle, and interphalangeal valgus (14) .Such evalua tions are important because they are related to patient satisfaction (7) and the possibility of recurrence (4,16,17) , as was demonstrated in the present study because there has been no recurrence to date.HVA: hallux valgus angle; IMA: intermetatarsal angle; Sgarlato: adduction angle of the forefoot measured by the Sgarlato technique (12) ; Engel: adduction angle of the forefoot measured by the Engel technique (13) ; SD: standard deviation; p: p-value.Source: Prepared by the author based on the results of the research.HVA: hallux valgus angle; IMA: intermetatarsal angle; Sgarlato: adduction angle of the forefoot measured by the Sgarlato technique (12) ; Engel: adduction angle of the forefoot measured by the Engel technique (13) .Source: Prepared by the author based on the results of the research.For the diagnosis of adduction of the metatarsals, the Sgarlato technique is the most widely accepted and used.The Engel technique was popularized due to its simplicity and ease of measurement when compared to the more traditional technique of Sgarlato et al. (15) .As there is no consensus in the literature on the best way to measure metatarsal adduction, we chose to perform this assessment using the two angles mentioned above.
In 2015, Aiyer et al. confirmed that the postoperative recurrence of hallux valgus was substantially higher in patients who had an associated diagnosis of metatarsus adductus compared to the group without this deformity, when only the first ray was addressed (16) .This finding supports the hypothesis, supported by other studies (4,17) , that the adduction of metatarsal muscles increases the risk of recurrence and suggests that the association of hallux valgus with metatarsus adductus should be addressed jointly, addressing the lateral rays to allow correction of the first ray.This fact was demonstrated in our study by the significant postoperative improvement of the hallux valgus angle, without recurrence of the deformity in the postoperative follow-up period.
Due to the adduction of the lateral rays, there is a restricted space for lateral translation of the first metatarsal head, which limits the power of correction of any isolated osteotomy of the first metatarsal (16) .This reduction of the intermetatarsal angle requires that we approach the lateral metatarsals to make room for correcting the varus of the first metatarsal; otherwise, it becomes impossible to align the first metatarsal with the medial cuneiform.This correction was evidenced in the present study by the significant decrease in the forefoot adduction angles.
In a retrospective study with 19 patients diagnosed with severe metatarsus adductus treated with different techniques, the authors concluded that modified Lapidus arthrodesis led to a lower rate of recurrence of hallux valgus compared to isolated distal osteotomies of the first metatarsal, but only when performed together with realignment arthrodesis of the proximal joints of the second and third metatarsals and distal metatarsal osteotomies (18) .In our study, we chose to perform osteotomy at the base of the metatarsals of the central column due to the larger amount of metaphyseal bone and for maintaining mobility in the midfoot joints.Thus, we were able to abduct the approached rays, allowing the alignment of the first metatarsal with the medial cuneiform and the consequent significant improvement of the angular measurements.
The present study has some limitations, such as the small number of patients, the absence of a comparison group, and a short follow-up time.However, the findings indicate a possible treatment for hallux valgus when it is associated with metatarsus adductus, given the observed improvement of the hallux valgus angle and adduction angle of the metatarsals achieved following the proposed method.

CONCLUSION
The results show that Lapidus arthrodesis combined with rotational osteotomy at the bases of the second and third metatarsals allowed correcting the metatarsus adductus deformity associated with severe hallux valgus, leading to a significant improvement in the hallux valgus angle and the adduction angle of the metatarsals.

Figure 1 .
Figure 1.Sgarlato's angle: traditionally defined as the angle between the longitudinal axis of the forefoot (a) and the longitudinal axis of the midfoot (b).The first is represented by the axis of the 2nd metatarsus, while the midfoot axis is defined as the perpendicular line between the line connecting (c) the midpoint of the medial border (d) and the lateral border (e) of the midfoot.The medial border extends from the medial ends of the talonavicular joints to the first tarsometatarsal joint; the lateral border extends from the lateral ends of the calcaneocuboid joints to the cuboid (5th metatarsal) joints8 .Source: author's personal archive.

Figure 2 .
Figure 2. Engel's angle is the angle formed between the longitudinal axis of the intermediate cuneiform (a) and the axis of the second metatarsal (b)9 .Source: author's personal archive.

1 .
Release of the distal lateral contracture of the hallux 2. Medial exostectomy 3. Preparation of the first tarsometatarsal joint for arthrodesis 4. Oblique osteotomy at the bases of the second and third metatarsals to correct the adduction of the metatarsals 5. Reduction of the first tarsometatarsal joint and arthrodesis with correction of the varus deformity of the first metatarsal 6. Fixation of the oblique osteotomies of the second and third metatarsals after lateral rotation 7. Weil osteotomy with release of the lateral collateral ligament of the second and third toes to correct the metatarsophalangeal subluxation of the small toes

Figure 3 .
Figure 3. Weight-bearing anteroposterior radiograph of the foot of one of the patients showing the preoperative deformity and postoperative deformity correction.Source: author's personal archive.

Table 3 .
Comparison of preoperative and postoperative angular measurements

Table 4 .
Pre-and postoperative values of the angular measurements of the foot