Abstract
Background:
The surgical management of brachymetatarsia remains controversial, and choice is based on potential complications. We report a classification of complications based on severity, and we hypothesized that use of a semicircular external fixator would minimize severe complications in lateral metatarsal lengthening.
Methods:
We retrospectively reviewed 30 patients (10 to 46 years old) with single or multiple brachymetatarsia and performed 54 metatarsal lengthenings with a mean follow-up of 7 months.
Results:
The mean gain in length was 15 mm (33.7%), and the mean healing index was 67 d/cm. No further procedure was performed. No dislocations or subluxations were reported, but 26 complications (48.1%) occurred, classified as 1 severe (1.8% of the metatarsals), 5 intermediate (9.3%), and 20 benign (37%): 4 incomplete osteotomies, 8 adjacent metatarsal osteotomies, 2 involuntary adjacent metatarsal fixations due to the lack of fluoroscopy use, 6 early consolidations, 2 metatarsal fractures, 2 skin complications, 1 superficial infection, and 1 metatarsophalangeal clinodactyly.
Conclusion:
A classification of complications based on severity was developed. Gradual lengthening of the lateral metatarsals by semicircular external fixation reduced the risk of severe complications because of stability without donor site morbidity. Thin wires were an advantage in the pediatric population.
Level of Evidence:
Level IV, retrospective case series.
Keywords
Congenital brachymetatarsia is bilateral in more than 50% of cases with a likely underestimated incidence (0.02% to 0.05%) and a female preponderance (25:1).17,24,31,32 Brachymetacarpia is commonly associated with systemic disease.5,7,8 The fourth metatarsal is the most frequently involved, followed by the third. Several rays can be involved, resulting in a cosmetic issue.9,21,23,25,28 Pain by abnormal distribution of the plantar pressure with formation of calluses is common.2,5,6,10,19,30,32 The dorsal position of the toe above the corresponding commissure may lead to skin irritation in shoes. 6
Several operative procedures have been described to restore a normal metatarsal head parabola with good results, but many complications were reported.2,4,17,28 The most widely used procedures are 1-stage metatarsal lengthening (OL) by bone graft interposition, with or without shortening of the adjacent metatarsals, or gradual lengthening (GL) by external fixation. The main advantage of OL is a decreased period of bone healing. Disadvantages are the donor site morbidity and the relative inability of the surrounding soft tissues to stretch with a smaller gain in length. The GL method—usually described with a unilateral fixator because of its small size and its simplicity of use—mitigates these limits.3,29 Nevertheless, Ilizarov described the importance of frame stability and the advantages of the circular fixator in bone lengthening to avoid severe complications, such as malalignment, joint subluxation, frame breakage, and failure of lengthening as described with the unilateral external fixator.11-14,19,21,26,28
We hypothesized that the use of a stable semicircular external fixator would reduce the risk of severe complications in metatarsal lengthenings. The technique, advantages, and complications are discussed, including a literature review and a classification of the complications according to severity.
Methods
Patients included those with congenital brachymetatarsia without previous surgery who were operated on by 1 of the 5 surgeons at the Russian Ilizarov Scientific Center, Kurgan, Russia, between February 2002 and June 2013. Shortenings were excluded if they were less than 5 mm as compared with the Lelièvre parabola that harmoniously connects the metatarsal heads on an anteroposterior foot X-ray.5,16,22 This study was performed in accordance with national ethical guidelines from the Committee for Clinical Research in Humans and the 1975 Declaration of Helsinki revised in 2000. Age and reason for consultation were recorded, including cosmetic or functional problems (foot pain and plantar hyperkeratosis, footwear difficulties). Data recorded preoperatively and at the last follow-up included the following: metatarsal length (distance between proximal and distal joint surfaces at the crossing points with the mechanical axis of the segment), Lelièvre parabola, and length required to restore this parabola. Postoperative data included distraction period, fixation period, distraction rate, and complications (fracture, infection, early consolidation, nonunion, subluxation, malalignment)
Epidemiologic Data
This series included 54 metatarsals (46 feet) in 30 patients, all female, operated for functional issues in 19 cases (Table 1). The mean age was 20.5 ± 9 years (range, 10 to 46), including 6 children, defined by radiologic open growth plate (14 metatarsals, 25.9%) with functional issues. The mean follow-up period was 187 ± 203 days (range, 62 to 884). Both feet were affected in 16 cases and multiple rays in 8 cases, operated in only 1 operation. In 4 cases, the metatarsal lengthening surgery was associated with another process that modified the global design of the frame without variation in the metatarsal lengthening protocol.
Details of the Epidemiologic Data of the Series. a
Abbreviations: AD, adult population; M1, first metatarsal head; M2, second metatarsal head; M3, third metatarsal head; M4, fourth metatarsal head; PED, pediatric population.
Values presented as No.
Per foot.
Data analysis included the following:
Achieved gain: difference between post- and preoperative metatarsal lengths
Desired gain: distance between the distal end of the metatarsal head and its normal position with a harmonious metatarsal parabola restored on the first radiograph
Percentage of gain in length: ratio between achieved gain and initial length
Healing index: ratio between healing time (number of days from operation to frame removal) and achieved gain
All complications were recorded according to the classification proposed by Lascombes related to long bone lengthening and extended here to metatarsal bones. 18 We adapted this classification in 3 groups of severity:
Benign complications: types I and II of Lascombes classification—namely, lengthening with desired gain obtained, respected previous function, and respect of the calculated deadline based on the mean healing index of the literature in the same indication (67 d/cm)
Intermediary complications: type III with desired gain obtained or not, respected function, but healing index higher than the literature
Severe complications: other complications
Technique Description
A GL was performed for 1 or more metatarsals using a semicircular external fixator according to a standardized protocol without tourniquet under regional or general anesthesia (Figures 1, 2). A half-ring used as a stable base was fixed at the midfoot using 2 or 3 K-wires between the tarsometatarsal and transverse tarsal joints and on the metatarsal bases. One threaded rod per metatarsal was fixed to this single proximal half-ring and attached distally to the metatarsal shaft by 3 or 4 wires, taking care to avoid any damage to the extensor digitorum longus tendon. The rod position was parallel to the plantar foot surface in the sagittal plane and just between the 2 adjacent metatarsal heads in the transversal plane. The first phalanx base was fixed to the rod by 2 wires for metatarsophalangeal (MTP) joint immobilization. A temporary intramedullary arthrorisis wire fixed to the rod bridged the interphalangeal (IP) joints only. A second rod connected the first to the ring to increase stability. A longitudinal incision (0.5 to 1 cm) on the dorsum of the affected metatarsal was followed by an extracapsular osteotomy using an osteotome on the base of the metatarsal without preperforation, to avoid injury of the surrounding structures and thermal damage. The frame was extended to the hindfoot when tibial or hindfoot correction was indicated for another pathology.
A, This is an example of a brachymetatarsia of the fourth metatarsal. B, This method uses exclusively thin wires. A half-ring is fixed at the midfoot. It is connected to the concerned metatarsals by threaded rod attached distally to the metatarsal shaft by 3 or 4 wires. To avoid any joint complication, phalanges are temporarily attached to the rod by 2 wires on the base of the first phalanx and an arthrorisis wire bridging the interphalangeal joints. A second threated rod improves the stability. The percutaneous osteotomy uses an osteotome by a very small skin incision. This frame can be used for several brachymetatarsia and extended to other segments if another pathology dictates. C, The distraction step begins on day 6. D, Frontal view on fixation step, after removal of the arthrorisis wire. E and F, Lateral views on fixation step.
Bilateral multiple third- and fourth-ray brachymetatarsia can be managed by Ilizarov method. A1, Before surgery, the dorsal position of the fourth ray can be a painful issue. A2, The preoperative plantar picture shows calluses on the fifth metatarsal head by abnormal plantar pressure distribution. A3, X-rays confirm the diagnosis: drawing the Lelièvre parabola, there is a shortening of more than 5 mm of the third and fourth metatarsal bones of both feet. B1, Unique or multiple brachymetatarsia are treated by the same protocol with the Ilizarov method. Phalanxes are free during the fixation step on the left foot and fixed during the distraction step on the right foot. B2, The patient is allowed to walk during both steps. B3, The regenerate is monitored by X-ray. C1, C2, The frame is removed without anesthesia when the length is considered adequate as confirmed clinically and/or by X-ray (C3).
Postoperative care included dressing change around the wires with antiseptic solution on day 1 and then every 10 days. Ankle mobilization and weight bearing begun as tolerated from day 1 using a dedicated foam sole without anticoagulation.
Distraction started from day 6 ± 2 with a rate of 0.25 mm 2 to 4 times per day depending on the initial clinical and radiologic data (diastasis created during surgery, tolerance, radiographic regenerate findings). When the length, assessed every week by X-rays, was appropriate, the fixation period began, and the arthrorisis wire was removed.
Frame removal was carried out after assessing the strength of the regenerate with radiologic and manual testing for the absence of motion of this area after frame unlocking. Full weight bearing was recovered progressively using 1 crutch after frame removal or 2 crutches with a thermoformed posterior leg splint for 20 days in cases of both feet surgery. Sports were allowed 3 months after frame removal for all patients.
Results
Lengthening Features
The mean obtained gain was 15 mm (range, 7 to 27), 35% of the initial length (range, 15% to 100%; Table 2). The mean time to removal of the arthrorisis wire was 65 days (range, 26 to 111). The mean time to frame removal was 91 days (range, 62 to 152), and the mean healing index was 67 d/cm (range, 36 to 127).
Results of the Metatarsal Lengthenings of this Series. a
Data are shown as No. or mean ± SD (range).
Complications
No frame breakage, subluxation/dislocation, joint stiffness felt by patient, and further procedure (eg, plantar capsulotomy, tendon lengthening) were reported (Table 3). Twenty-six complications (48.1% of the metatarsals) occurred in 20 feet. Sixteen complications (62% of the complications) were the consequences of technical errors (incomplete osteotomy, osteotomy or fixation of the adjacent metatarsal). Concerning the remaining 10 complications, there were 2 cutaneous wounds (by the wire during lengthening period in one case and by a fixator too close to the skin in the other), 1 superficial pin track infection, 6 early consolidations requiring a new surgery for osteotomy in 5 cases, and 1 clinodactyly of the toe due to a malposition of the IP arthrorisis wire, which resolved with stretching. Finally, 10 metatarsals (18.5%) required a secondary surgery.
Complications of the Lateral Metatarsal Lengthenings in This Series Based on Severity and Adapted From Lascombes Classification (n = 26). 18
Gain, timing, and function respected.
Gain, timing, and function respected, with need of new anesthesia before end distraction time.
Secondary surgery required.
Gain and function respected. Healing index more than 67 d/cm (mean value in the literature).
Function respected, gain less than 75% of the desired gain. Healing index more than 67 d/cm (mean value in the literature).
Affected function, gain less than 75% of the desired gain.
All complications were classified according to Lascombes classification: 14 level I, 6 level II, 4 level IIIa, 1 level IIIb, 1 level IVa. According to the criteria previously described, 1 severe complication occurred (1.8% of the metatarsals; Figure 3), 5 intermediary complications (9.3%), and 20 benign complications (37%).
Brachymetatarsia of the fourth ray. The only one severe complication of the series: deformity by synostosis between the third and fourth rays. A, Before surgery, the dorsal position of the fourth ray can lead painful and cosmetic issues. B, The preoperative radiograph confirmed diagnosis. C, The postoperative radiograph showed an involuntary complete osteotomy of the adjacent third metatarsal not noticed during the surgery due to the absence of fluoroscopy use. D, The synostosis and the deformity observed after removal of the frame are a severe complication.
Radiologic Analysis
In 89.1% of the feet (41 of 46), Lelièvre parabola was restored with less than 5 mm of tolerance, the threshold value defining the brachymetatarsia.
Discussion
Surgical management remains controversial between acute lengthening and GL in brachymetatarsia. OL reduces healing time and patient discomfort with a smaller gain due to resistance of the soft tissues and multiple scars from bone graft use with possible skin necrosis or recurrences due to shortening by graft resorption. Shortening of the adjacent metatarsal has been described, and it transforms a unisegmental surgery into a complex surgery with increased nonunion risk.1,4,16,17,20,21 Studies of GL using unilateral external fixator relate malalignments and joint subluxations. Only a few studies (Table 4) have reported large series. We reported on 54 metatarsal lengthenings with a stable external fixator to minimize severe complications and previously described complications. Our results are similar to those based on series of more than 10 patients from the international literature (Table 4): mean gain, 35% (OL: 26%, GL: 32%); mean healing index, 67 d/cm (OL: 58 d/cm, GL: 67 d/cm). Our mean complications rate was 48.1%, compared with 59.3% in the GL literature. The severity of complications must be distinguished. We used the Lascombes classification to stratify the complications. We reported only 1 severe complication (3.8% of the complications) and a majority of benign complications (77%).
Comparison of Lateral Metatarsal Lengthening Between the series of More Than 10 Patients From the International Literature and the Results of the 54 Lengthenings of This Series.
Calculated values on the basis of the corresponding article reading.
Including 2 first rays.
Including 1 first ray.
See Table 3.
On the basis of our series, we recommend the use of fluoroscopy. Indeed, most of our complications could have been avoided by its use, which was not a common practice; typically, it included unrecognized incomplete osteotomy or fixation of the adjacent metatarsal, which were found only during the distraction step by increasing MTP diastasis and in the absence of regeneration zone diastasis.
Moreover, our 6 early consolidations, all in children, point out the need for careful regenerate monitoring and probably an increase in the initial rate of distraction in children. No frame breakage, dislocation, subluxation, or ischemic complications were observed. One case of final deformity (Figure 3) was due to an involuntary complete osteotomy of the adjacent metatarsal (without fluoroscopy use) inducing a synostosis of the metatarsals.
Masada and Takakura suggested that more than 40% of elongation increases the risk of malalignment.25,29 As also reported by Shim and Park, our 9 lengthenings with more than 40% gain (40.1% to 100%) were not associated with increased complications. 27 Assuming that a high percentage lengthening can cause MTP subluxation, Beak and Chung used an intramedullary wire through the IP and MTP joints.2,15 In our technique, a semicircular base, an IP arthrorisis wire, and the fixation of the phalanges on the threated rod stabilized the joint complex, which was subjected to strong constrains without MTP damage. The intramedullary wire removal during fixation allowed early rehabilitation and reduced stiffness.
The small diameter of wires used was an advantage over unilateral external fixators, which typically use 2- to 3-mm pins with intraoperative fractures having been described. 27 This technique is suitable for small bones, especially in children and in cases of multiple brachymetatarsia, where multiple unilateral devices have a lack of space. 4
Our study has some limitations. Our 6.7 months of follow-up can be criticized. Nevertheless, all metatarsal bones were consolidated, so there was no risk of resorption due to the absence of graft use. We do not have long-term clinical data. However, some authors have demonstrated the effectiveness of GL in this pathology; our series provides a new concept of classification in GL and a technical variant to limit severe complications inherent in the relative instability of the unilateral fixators.2,4,19,21,26,30
Conclusion
GL of the lateral metatarsal bones by semicircular external fixator is one method of management of brachymetatarsia. A classification of complications based on severity is proposed here for lengthening evaluation. This technique reduced the risk of severe complications, such as malunion, malalignment, and MTP or IP dislocation because of better stability of the frame as compared with other external fixation methods. The use of thin wire made it easy for implementation in children. This technique allowed, without donor site morbidity, a greater gain than that of OL techniques and immediate weight bearing. This procedure should always be done with fluoroscopy.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.