Bilateral Staged Distraction Osteogenesis of the Fourth Metatarsal With Biplanar First Metatarsal Osteotomies in an Adolescent Athletic Patient: A Case Report

Introduction

Brachymetatarsia is defined as an abnormally short metatarsal due to a variety of either acquired or congenital causes.^1,2 The fourth metatarsal is the most affected. The finding has an incidence up to 0.05% of the population and is more frequently found in female patients with up to 72% cases describing bilateral findings.^1,3 Hallux valgus is identified as lateral deviation of the hallux and medial deviation of the first metatarsal.^4,5 In this case, the patient presented with juvenile hallux valgus, characterized by a congruent first metatarsophalangeal (MTP) joint articular surface despite the angular deformity. It likely arises primarily from genetic predisposition and altered first-ray biomechanics.^4,5 Hallux valgus is more commonly presented bilaterally. ⁶ Coexistence of bilateral fourth-ray brachymetatarsia and bilateral hallux valgus presents biomechanical and cosmetic concerns, as shortening of the fourth ray alters the metatarsal alignment and increases medial loading of the foot through the first ray.^1,7 Distraction osteogenesis offers a gradual and quantifiable means to restore the metatarsal length while allowing for soft-tissue adaptation.^8,9 Distraction osteogenesis, however, requires patient education and close postoperative monitoring to identify and manage complications.^10,11 Although there is literature on outcomes of metatarsal distraction and juvenile hallux valgus correction, there is limited literature describing the combined staged use of these techniques in an adolescent patient presenting with these symptoms bilaterally.^1,8,9 The present case documents the surgical steps and management that enabled positive outcomes in an active adolescent patient and is notable given the rarity of concurrent bilateral hallux valgus and fourth-ray brachymetatarsia. To our knowledge, no prior reports describe a staged combined approach of first-ray realignment and metatarsal distraction osteogenesis for coexisting bilateral hallux valgus and fourth-ray brachymetatarsia in an adolescent and demonstrated that previously described distraction techniques with an external fixator may allow for concomitant procedures to be performed.

Materials and Methods

An otherwise healthy 15-year-old female patient presented with a 3-year history of progressive bilateral forefoot pain exacerbated by increased exertion and use of tight footwear. Physical examination revealed bilateral hallux valgus with medial prominence of the first metatarsal heads as well as short fourth toes (Figure 1). Weight-bearing radiographs displayed increased intermetatarsal angles of 13° bilaterally, hallux valgus angles of 36° on the right and 32° on the left, and evidence of bilateral fourth-ray brachymetatarsia (Figures 2 and 3). The patient and family were educated regarding alternatives, including acute lengthening and nonoperative measures. Activity limitations were the primary motivating factors for operative alternatives. In addition, she had previously tried extensive shoe wear modifications without meaningful relief and reported daily pain in closed-toe footwear, as well as a complete inability to tolerate cleats for sports participation, ultimately forcing cessation of athletic activities. Due to these grievances, in addition to persistent pain and functional limitation, the patient and guardians elected staged operative plans to restore a comfortable forefoot alignment.^4,8

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Figure 1.

Preoperative clinical image showcasing gross appearance of bilateral fourth-ray brachymetatarsia and bilateral hallux valgus.

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Figure 2.

Preoperative radiograph of right foot showcasing fourth-ray brachymetatarsia and display of hallux valgus angle of 36°.

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Figure 3.

Preoperative radiograph of left foot showcasing fourth-ray brachymetatarsia and display of hallux valgus angle of 32°.

Initial operation was conducted on the right lower extremity per patient preference. Operatively, a biplanar distal first metatarsal chevron osteotomy was performed to correct juvenile hallux valgus. The dorsal limb of the chevron included a closing wedge osteotomy to correct the distal metatarsal metaphyseal angle. The distal fragment was medialized and stabilized with percutaneous Kirschner wire (K-wire) fixation. For the fourth metatarsal, a percutaneous proximal osteotomy of the fourth metatarsal was then created and stabilized with a MiniRail external fixator (OrthoPediatrics, Warsaw, Indiana) with the intention of allowing distraction osteogenesis (Figure 4). Postoperatively, the patient was educated and given a metatarsal lengthening protocol consisting of one fourth turn 3 times daily, which equaled 0.175 mm lengthening per one fourth turn or roughly 0.525 mm lengthening per day. Preoperative templating suggested a goal of approximately 13.5 mm of lengthening. ⁹ Following osteotomy, a 7-day latent phase was observed to allow inflammatory markers to dissipate; the patient maintained nonweight-bearing in a controlled ankle motion boot during a 7-week distraction phase with serial radiographs for monitoring length and regeneration formation. Once radiographic and clinical exam demonstrated appropriate length, distraction was stopped, allowing the regenerate to consolidate over the course of 12 weeks. After appropriate consolidation, the MiniRail was removed in the clinical setting. During this time, the first metatarsal biplanar osteotomy had gone on to uneventful healing and K-wire removal in the clinic. After functional recovery of the right side, the contralateral foot was treated with a similar approach, resulting in a 7-day latency phase, 4-week active distraction phase, and 12-week consolidation phase, with successful deformity correction and healing without operative incident. Prophylactic systemic antibiotics were not routinely prescribed for pin-site infection prophylaxis, and a structured pin care protocol consisting of daily cleansing of pin sites with antiseptic solution and maintenance of dry sterile dressings was followed.

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Figure 4.

Intraoperative image of right foot showcasing gross appearance of fourth-ray osteotomy stabilized with a MiniRail external fixator (OrthoPediatrics, Warsaw, Indiana) for allowing distraction osteogenesis.

Transient dorsal subluxations of the fourth MTP joint were identified. This was managed nonoperatively with external fixator adjustment. No additional operative procedures were required. The subluxation resolved with continued controlled distraction and restoration of metatarsal length, with maintained joint congruity at final follow-up.

Results

At 13 months following the initial right foot procedure and 5 months following the contralateral procedure, the patient demonstrated healed osteotomies, maintained alignment of the first rays, and successful consolidation of the bilateral fourth metatarsals, with restoration of forefoot alignment^8,12 (Figure 5). The patient-reported resolution of preoperative pain, tolerated standard footwear, and had returned to baseline activity. At the latest follow-up, the fourth MTP joints bilaterally demonstrated congruent alignment without subluxation, and range of motion was functionally preserved with mild residual stiffness early in recovery that improved with rehabilitation and did not limit activity. The patient returned to full unrestricted daily activities with progressive return to running and recreational athletic participation without pain or functional limitation. No complications or recurrence of deformities were noted at this time. This staged strategy resulted in a favorable radiographic (Figures 6 and 7) and clinical outcome in an adolescent patient with bilateral combined hallux valgus and brachymetatarsia.

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Figure 5.

Clinical image demonstrating gross appearance of restoration of bilateral fourth-ray length and bilateral corrected hallux valgus deformity following staged biplanar first metatarsal chevron osteotomy and distraction osteogenesis.

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Figure 6.

Postoperative radiograph of the right foot demonstrating restoration of fourth-ray length and corrected hallux valgus deformity following staged biplanar first metatarsal chevron osteotomy and distraction osteogenesis.

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Figure 7.

Postoperative radiograph of the left foot demonstrating restoration of fourth-ray length and corrected hallux valgus deformity following staged biplanar first metatarsal chevron osteotomy and distraction osteogenesis.

Discussion

Brachymetatarsia of the fourth ray and juvenile hallux valgus represent 2 interrelated disturbances of forefoot form and function. Shortening of the metatarsals alters the forefoot alignment and plantar load distribution, and malalignment of the first-ray concentrates pressure medially and contributes to footwear intolerance, pain, and activity limitation.^1,3-5 Brachymetatarsia often results in a dorsally positioned toe. Hallux valgus is characterized by a large medial prominence. Both pathologies potentially cause discomfort and complicate closed-toe shoe wear. Brachymetatarsia and hallux valgus may arise independently, but literature suggests a biomechanical relationship. Thomas et al ¹³ found a 30% prevalence of hallux valgus in feet with brachymetatarsia which exceeds the general population prevalence. Fourth-ray shortening disrupts the metatarsal parabola and redistributes plantar loading medially, which may promote first-ray malalignment in predisposed individuals. ¹³ In this case, bilateral coexistence of both deformities in a young patient without other identifiable risk factors could support a contributory relationship. Nonoperative management, including shoe modification, orthotics, activity modification, anti-inflammatory regimens, and targeted physical therapy, should be pursued first. These may provide symptomatic relief. Nonoperative treatments may be insufficient for patients whose athletic participation is limited by pain or mechanical dysfunction in comparison to less active adolescents.^1,8 In this case, an extensive trial of nonoperative modalities was exhausted without appropriate symptomatic relief.

Surgical strategies to address brachymetatarsia broadly divide into acute lengthening with structural bone grafting and gradual lengthening with distraction osteogenesis. Given the need for controlled-length restoration and soft-tissue accommodation, gradual distraction osteogenesis was selected over acute lengthening.^8-10 Recent pediatric literature supports the safety and effectiveness of gradual metatarsal lengthening using small-rail external systems in appropriately selected patients.^8,9

Distraction protocols employing daily rates near 0.5 mm will balance the biologic requirement for new bone formation against soft-tissue tolerance with the risk of regenerate failure; such rates have been reported to achieve clinically meaningful length gains of 10 to 15 mm or more with acceptable consolidation times in multiple series.^7,9 The choice of rate, device alignment, osteotomy level, and early follow-up cadence are parameters critical for consideration.

Complications with distraction osteogenesis in the foot are well documented and can be frequent, particularly when aggressive lengthening is attempted or when MTP joint stability is compromised.^7,10,11 Reported complication rates vary widely across series, with some reviews describing complication incidences that range broadly and emphasizing issues such as MTP joint stiffness, subluxation, pin-site infection, skin tethering, and delayed consolidation.^{9 -11} Furthermore, misalignment of the distractor axis or unrecognized cortical tethers can induce angular deformity or device failure. Inadequate pin care or excessive mechanical insult raises the risk of pin-site complications.^10,11 Early clinical detection and management of complications arising is key.

Several factors likely contributed to the absence of complications in this case. A conservative distraction rate of approximately 0.5 mm/day was employed, consistent with protocols associated with favorable outcomes in fourth metatarsal lengthening.^7,9 Serial radiographic monitoring during active distraction allowed assessment of regenerate quality and early detection of malalignment. Thorough preoperative education and a structured pin-site care protocol promoted patient compliance, which is a recognized determinant of outcome in distraction osteogenesis.^8,10 The staged bilateral approach additionally allowed the patient to gain familiarity with the distraction protocol before the contralateral procedure. The lengthening target of approximately 13.5 mm was determined by preoperative radiographic templating to restore the fourth metatarsal within the normal metatarsal parabola. Reported complications, particularly MTP joint subluxation and stiffness, were concentrated in metatarsals lengthened more than 40% of their original length, which reinforces the importance of conservative and parabola-guided length endpoints rather than purely cosmetic ones. ¹⁴

These risks argue for conservative planning, including limiting percentage-length increases, meticulous pin-site protocols, early and frequent clinic monitoring during the active distraction phase, and proactive rehabilitation to preserve joint range of motion.^1,10,11 Several investigators have warned that excessive lengthening correlates with higher complication rates. This is often quantified as a percentage gain relative to native metatarsal length. This suggests practical limits to safe distraction in small metatarsals and reinforces the need to quantify final length endpoints toward functional rather than purely cosmetic.^8,10,11

When hallux valgus coexists with brachymetatarsia, addressing the first ray concurrently or in a staged fashion is important to restore the alignment of the forefoot. Outcomes for juvenile hallux valgus surgery are generally favorable in contemporary series when deformity correction is appropriate for skeletal maturity and technique, with many patients reporting good or excellent functional results. Nonetheless, recurrence and residual symptoms may persist, requiring individualized preoperative planning and extensive patient counseling.^4,12 When considered separately, the literature supports distraction osteogenesis as an effective option for metatarsal lengthening and the use of biplanar chevron osteotomies for juvenile hallux valgus in the adolescent population.^1,8-11 The present case contributes a practical example for the concomitant use of the procedures

Limitations include being a single-case report that includes the absence of standardized and validated patient-reported outcome instruments and objective biomechanical testing, such as gait analysis or plantar pressure mapping, in the available follow-up.^5,15

The significant of this case is particularly notable for demonstrating the combined use of biplanar first metatarsal osteotomy and distraction osteogenesis of the fourth metatarsal in an adolescent bilaterally. While hallux valgus and brachymetatarsia are each independently challenging to manage in adolescents, their coexistence amplifies both the functional and cosmetic concerns; this is especially true when found bilaterally.^1,4 In young active patients, uncorrected deformity can impair footwear tolerance, exacerbate forefoot pain, and limit sport participation. By employing this approach that prioritizes function and patient engagement, this case illustrates the feasibility of addressing both deformities in a manner that restored functional forefoot alignment and facilitated safe return to activity.^4,8,12

Conclusion

In summary, we present the case of an adolescent patient with bilateral juvenile hallux valgus and congenital fourth-ray brachymetatarsia treated successfully with biplanar first metatarsal chevron osteotomies and distraction osteogenesis of the fourth metatarsals. The bilateral coexistence of both deformities, consistent with the elevated prevalence of hallux valgus reported in brachymetatarsia supports a biomechanical relationship that warranted concurrent correction. The patient achieved restoration of forefoot alignment and resolution of activity-limiting pain. She returned to her baseline activity. We believe that this case highlights the feasibility and therapeutic potential of combining hallux realignment with metatarsal lengthening in adolescents and supports further exploration of this strategy as a reproducible treatment pathway for complex bilateral forefoot deformities in adolescents.^1,4,8,9,12