Growth Modulation for the Treatment of Juvenile Hallux Valgus: A Systematic Review of Literature

INTRODUCTION

Hallux valgus (HV) is a complex deformity of the forefoot involving the first ray; it is characterised by valgus deviation of the proximal phalanx and varus deviation of the metatarsal producing an apex of deformity at the first metatarsophalangeal joint. Hallux valgus in children, also known as juvenile hallux valgus (JHV), is a relatively uncommon deformity that may cause progressively worsening pain.¹ The exact pathophysiology of JHV is not well understood, but a strong hereditary component has been demonstrated in the literature.^2,3

Treatment for JHV is controversial due to limited data supporting any specific intervention. There are no studies which compare surgical or non-surgical treatment. The surgical options are often pursued in symptomatic patients when conservative management fails. Osteotomies in skeletally immature patients showed unacceptable rates of recurrence of the deformity and unsatisfactory outcomes.^2,4–8 Alternatively, various techniques of growth modulation have been described, including, but not limited to, temporary screw lateral hemiepiphysiodesis, lateral drilling hemiepiphysiodesis and lateral hemiepiphyseal stapling.

Lateral hemiepiphysiodesis of the first metatarsal is emerging as a good option for treating symptomatic patients with HV who have not yet reached skeletal maturity. The described techniques are relatively simple and have low complication rates.⁹ The principle was first described in 1951 by Ellis.¹⁰ Since then, the principle of growth modulation has been utilised variously in treating JHV. Despite the favourable outcomes reported in some studies, the sample sizes are small and lack long-term outcome measurements.^11–14 The objective of this study was to perform a systematic review of the literature for JHV treated with growth modulation techniques.

MATERIALS AND METHODS

Two authors (MA and JPP) performed independent PubMed and EMBASE database searches for articles on growth modulation for the treatment of JHV, published on or before December 1, 2021. The following subject headings and related key terms were used: “juvenile hallux valgus” or “pediatric (paediatric) hallux valgus”, “growth modulation”, “hemiepiphysiodesis” or “hemiepiphysiodesis”, “epiphysiodesis” or “epiphysiodesis”. The exact search strategy was as follows: (((juvenile) OR (pediatric) OR (paediatric)) AND ((Hallux Valgus) OR (bunion))) AND ((Screw) OR (growth modulation) OR (hemiepiphysiodesis) OR (epiphysiodesis) OR (epiphysiodesis) OR (hemiepiphysiodesis)).

Inclusion criteria for the systematic review consisted of: (i) all levels of evidence, (ii) skeletally immature patients, (iii) hallux valgus treated with growth modulation and (iv) English language of publication. Exclusion criteria included: (i) review articles, (ii) conference abstracts, (iii) articles available in abstract format only (full-text not available online) and (iv) JHV treated with methods other than growth modulation (e.g., metatarsal osteotomy).

The titles and abstracts were screened by the two authors independently for their eligibility for inclusion. Articles considered to meet the criteria were reviewed in full by the same two authors independently. Subsequently, pertinent information from the included articles were retrieved and entered into a Microsoft Excel spreadsheet (Microsoft Excel for Mac, Version 16.4, Microsoft, Redmond, WA, USA). These included article information (author, year of publication, study design, level of evidence and sample size), patient demographics and clinical characteristics (age, pre-operative hallux valgus angle (HVA)), pre-operative intermetatarsal angle (IMA), method of growth modulation and post-operative follow-up data (duration of follow-up, degree of correction of HVA, degree of correction of IMA, complications, revision rate and functional outcome measures). All studies performed HVA and IMA measurements on pre-operative and post-operative plain radiographs.

The primary outcomes sought were the degree of correction of HVA and IMA whereas secondary outcomes included complications, revision rate and functional outcome measures. Due to the small number of articles available in literature and significant heterogeneity in the method of growth modulation utilised in the articles, a meta-analysis was not feasible; instead, a qualitative assessment of the identified articles was performed.

RESULTS

DISCUSSION

Hemiepiphysiodesis of the first metatarsal was described as a procedure that takes advantage of the residual growth potential to correct the deformity slowly. Several techniques, either by permanent or temporary fixation of the lateral physis, have been used since the principle was first described in 1951. The outcomes of these techniques are favourable in treating HV in skeletally immature patients despite the variability in the surgical technique used.

Objective assessment of severity of JHV was done by measuring the HVA and IMA on plain radiographs. Regardless of the surgical technique used for growth modulation of the first metatarsal, there is significant correction of both HVA and IMA. However, correlation between the degree of correction and functional outcome measures was lacking.

High recurrence rates of HV deformity have been reported in patients who were treated by osteotomy before skeletal maturity;^2,4–8 however, there are no studies comparing the outcomes of hemiepiphysiodesis and osteotomy procedures. Moreover, the distal metatarsal articular angle (DMAA), if measured to be 10° or more on plain radiographs, is considered pathologic and may be seen in more severe cases of JHV.² Nevertheless, it is unclear whether hemiepiphysiodesis of the first metatarsal helps to correct this deformity. If found to be not correctable by hemiepiphysiodesis, an increased DMAA may be a contributing factor for persistent deformity or recurrence or both. Although the angular correction may not be clinically significant, this might make future correction osteotomies less complex.

The optimum timing for surgical intervention is uncertain. This is due to the unknown natural history of JHV and the unique growth potential of the metatarsals making an estimate of remaining growth unclear.^19,20 In fact, Greene et al. showed that the overall plot of the foot multiplier curve for estimating the remaining growth in the foot is vastly different from other body regions.¹⁹ Except for one case report,¹⁵ the mean age of the patients in all studies was between 10 and 12 years. Owing to the progressive deformity in JHV and the uncertain natural history of the condition, some studies advocate for surgical intervention after skeletal maturity.^2,7,21,22 However, the impact of pain and activity limitations in severe cases of JHV make conservative management, reportedly with suboptimal outcomes, an unsuitable option for treatment.

The correlation between age and the degree of correction achieved was highlighted in three studies where greater correction was observed of the HVA in younger patients.^13,17,18 This may be due to a larger remaining growth potential in these patients which compensates for the slow rate of correction with hemiepiphysiodesis. The metatarsal growth rate slows down and was found to decrease markedly in children as they approach skeletal maturity; therefore, more correction can be achieved with hemiepiphysiodesis at a younger age.^23,24 Interestingly, AlFarii et al.¹⁷ observed worsening of the HV deformity in three patients with comorbidities (periventricular leukomalacia, down syndrome and tight heel cord) despite surgical intervention. Chiang et al.¹⁸ were the only ones who reported on the gender ratio and ages of interventions; they included 9 male (mean age 13.0 years, SD 1.1) and 12 female (mean age 11.2 years, SD 0.9). Documented skeletal maturity at follow-up was only reported by Davids et al.¹¹ Neither of these studies performed subgroup analyses on the impact of these variables on the results or the final outcome. Further studies investigating the correlation between bone age and comorbidities to the degree of correction are needed.

The presence or absence of complications after surgical intervention were reported in six papers. There were no complications in three, while another three had low rates, including screw migration in 5% and one case of fracture of the base of the first metatarsal. Late complications included pain from symptomatic hardware, as was reported by Schlickewei et al.¹³ in 7.7% of cases, while AlFarii et al.¹⁷ reported symptomatic residual deformity in 17.3% of the cases. Regardless of the technique used, complications were relatively uncommon and were likely due to the minimally invasive approach of the technique as compared to the other surgical methods of treating JHV.^11,13,14,18

In all the studies, a significant correction of HVA and IMA on the follow-up radiographs was observed regardless of the surgical technique used. Although this may support using growth modulation for treating HV deformity in skeletally immature patients, several limitations have to be taken into consideration. Firstly, the duration of follow-up may not be sufficient to evaluate patient outcomes objectively, given that a significant proportion of participants in the studies had yet to reach skeletal maturity. Secondly, six studies were retrospective case series or cohort studies, and two studies were case reports. The relatively small number of study participants in each study, the significant heterogeneity in the utilised techniques and the lack of objective functional outcome measures prevent the drawing of any conclusions to advocate for one specific technique of growth modulation over another. A well-designed randomised controlled trial with sufficient statistical power will be helpful to determine the optimal method of growth modulation for the treatment of JHV.

CONCLUSION

Growth modulation for HV in skeletally immature patients via lateral hemiepiphysiodesis with minimally invasive techniques showed favourable radiologic outcomes with some evidence of clinical improvement. Although the radiologic change is relatively small, this may ease future correction osteotomies of HV deformity. Larger prospective studies with objective clinical outcome measures may further determine the place of this surgical approach as a means to treating this deformity.

ORCID

Yousef Marwan https://orcid.org/0000-0001-5450-523X

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