Functional and radiographic outcomes of hallux valgus correction by mini-invasive surgery with Reverdin-Isham and Akin percutaneous osteotomies: a longitudinal prospective study with a 48-month follow-up

Hallux valgus (HV) is a common, complex and progressive deformity of the forefoot with multiple clinical symptoms and a multifactorial aetiology [1]. Painful HV is more frequent in women between 40 and 60 years old, although it can appear in younger people because of biomechanical influence, hind and midfoot pathologies or sports activities, which might cause an overload on the first ray [2, 3]. For its correction, a wide variety of bony procedures are described, associated or not with soft tissue release, including osteotomies at the level of the head, midshaft and base of the first metatarsal, as well as arthrodesis of the first metatarso-cuneiform joint [4‐7]. This demonstrates the complexity of the disease and the lack of a unique and most appropriate treatment, the choice of which continues to generate controversy [8].

At present, minimally invasive surgery (MIS) performed with minimal skin incisions (1–3 mm), an intraoperative image intensificator and without internal fixation [9] represents one of the most innovative approaches in forefoot surgery. This percutaneous dynamic management combines different procedures, most arising from the traditional open distal metatarsal osteotomy, in a mixed surgical strategy, according to the complexity of the deformity to be corrected [10‐14]. These methods are rapidly becoming popular, as they are quick to perform, allow 1-day hospitalization, decrease post-operative morbidity as well as recovery and rehabilitation times, and chiefly because they are better accepted by patients [9, 15].

Although the most commonly performed percutaneous procedures have already been well described, providing equal effectiveness, sometimes superior, to traditional open surgery [16], their use is not equally accepted and their outcomes still remain a matter of discussion in the orthopaedic community, particularly in cases where no internal fixation is used [17, 18]. The Reverdin-Isham percutaneous osteotomy was described as a novel intra-articular medial closing wedge osteotomy of the distal metatarsal, in combination with an Akin osteotomy, both performed without fixation, to align the first ray by medial rotation of the first metatarsal head and distal metatarsal articular angle (DMAA) correction [15, 19‐26]. Reverdin-Isham is not a complete osteotomy, as the MTT-1 lateral cortex is preserved; the closing wedge ensures contact of the metatarsal head with the metaphysis, and a special bandage is applied after surgery. In this way, no internal fixation is necessary. This allows the osteotomy to heal with the toe in its proper position, due to early weight bearing.

Since the end of the last century, MIS became widespread first in Spain and then in Europe by M. De Prado and P.L. Ripoll through their surgical practices and international theoretical-cadaveric courses, supported by the anatomical studies of Pau Golanó [20]. In 2002, the group GRECMIP (Groupe de Recherche et d'Enseignement en Chirurgie Mini-Invasive du Pied) began a project to develop and promote this new surgical treatment [26]. However, to the best of our knowledge, no previous study has evaluated the long-term results of this technique. Thus, the aim of this prospective study was to evaluate the radiographic and clinical outcomes of patients with mild-to-severe HV treated by MIS with Reverdin-Isham and Akin percutaneous osteotomy, following exostosectomy and lateral soft-tissue release.

Between May 2010 and May 2012, a consecutive series of 80 Caucasian patients with diagnosis of mild-to-severe HV were enrolled in this prospective study at our institution and underwent the Reverdin-Isham percutaneous osteotomy, following percutaneous Akin osteotomy and percutaneous lateral soft-tissue release. All of these operative procedures were performed by a single surgeon, the senior author (C.B.), who followed and checked the patients personally during the post-operative period. All subjects participating in this prospective study received a thorough explanation of the risks and benefits of inclusion and gave their oral and written informed consent to publish the data. Approval from the General Clinical Directorate of our institution was obtained to introduce the novel technique before starting the operations. The study was performed in accordance with the ethical standards of the 1964 Declaration of Helsinki as revised in 2000 and those of Good Clinical Practice.

Eighty feet, 43 right and 37 left, of 80 consecutively enrolled patients, met the inclusion criteria and were considered in the analyses. The median patient age at the time of the surgery was 51 ± 15.5 years (range 26–78). There were 75 women (93.4%) and 5 men (6.6%). None of the patients was lost during the different follow-ups.

Although in the last few years, the number of studies regarding the effectiveness of MIS in HV correction has increased [35‐37], to the best of our knowledge, this is the first prospective, single-centre study reporting outcomes of Reverdin-Isham percutaneous osteotomy in a consecutive, single surgeon, large patient series with a median follow-up of 48 months. Furthermore, no other report in the literature has assessed the results of this procedure at three different follow-ups. The study was designed to evaluate, on the basis of clinical and computer-assisted radiographic data, the validity and reliability of this percutaneous techniques for correction of mild to severe HV deformity.

In our cohort, the mean AOFAS score improved significantly until the last follow-up (Tables 1 and 2). An increase of 18.1 points 3 months after surgery was seen, further 6.7 points at 12 months and 33 points at the last follow-up. Moreover, more than half of the patients scored more than 90 points, while the median, statistically the more “powerful indicator,” was 91 points, in contrast to 52 points in the preoperative period. This clinical improvement was also evident in all patient sub-groups, almost in the same way, maintaining unaltered the gradient correlated to the degree of the deformity. In the sub-groups, the mean AOFAS score at the last follow-up was 87.1 points (Δ = +32.1) in the mild HV group, 86.6 (Δ = +32.7) in the moderate HV group and 83.7 (Δ = +30.2) in the severe one. Overall, the AOFAS score found in our study was comparable to those reported by different authors not only using minimally invasive techniques [10, 12, 13, 25, 26, 38], with or without osteosynthesis, but also with series of open surgical procedures using Chevron, Scarf or proximal metatarsal osteotomies [10, 13, 19, 39, 40]. In particular, our data was similar for patient demographic aspects and complications, including stiffness; however, our group of patients had a larger sample size and follow-up duration [10, 13, 19, 39]. At the last follow-up, only seven patients reported daily pain, compared to 63 cases (78.5%) of the preoperative period, while most of the subjects (73 cases; 91.5%) reported no pain or only mild occasional pain (Table 2). These percentages are similar to those of other studies [10, 24, 25]. Despite the anti-edema prophylaxis adopted, 40% of our subjects complained of swelling of the foot and ankle, which remained for more than a month after the operation. Apparently, the causes of both prolonged pain and swelling in these cases were related to the delayed formation of bone callus until the complete healing of the osteotomies seen at 3-month follow-up.

According to the AOFAS scale, the alignment was considered good in 55 cases (69%), discrete in 19 cases (23.5%) and poor in 6 (7.5%). Overall, in 92.5% of our cases, there was improvement, which is comparable with that reported in the literature [10, 25, 35, 38‐44] (Figs. 5 and 6).

One of the possible side effects of Reverdin-Isham percutaneous osteotomy, as it is an intra-articular medial closing wedge osteotomy, is the stiffness of the first metatarso-phalangeal joint [45, 46], which was noticed also in our cohort. Before the operation, 66 cases (82.5%) presented with preserved range of motion and the other 14 cases (17.5%) with slight limitation. After surgery, the joint movement was completely normal in 49 cases (61%) and was slightly reduced in another 30 cases (37.5%), while severe limitation to the flexion-extension was present only in an elderly patient. In accordance with Bauer et al., the potential cause could be the remains of bony fragments in the joint and the capsular tissues, produced during the extensive exostosectomy and the lack of accurate cleaning of the work area with rasps and irrigation with normal saline solution [35].

There were three intraoperative complications, which had resolved spontaneously by the final follow-up: one neuritis of a cutaneous sensory dorsal branch and two skin burns around the portal. Several studies have been reported in the literature [47, 48] comparing the complication rate between diathermy and scalpel for skin incision, without showing any significant differences. However, to the best of our knowledge, no study has examined the complication rate of surgical burr in MIS. In our experience, it is a fundamental surgical aspect to avoid putting too much manual pressure on the burr during the performance of osteotomies, rather accompanying it gently with the fingers during the entire process; otherwise, the resistant bone can push the burr to the edges of the portal, causing skin burn.

With regard to radiographic analysis (Table 3), all correction angular values obtained in our cohort were statistically significant (p < 0.0001). Although the distal closing wedge osteotomy has been described without resulting in any lateral translation of the metatarsal head, the IMA decreased from a mean value of 12.9° at preoperative examination to a mean value of 9.0° at the final follow-up, with a difference of 3.9° and an efficacy of 30.5% in angular value correction. In agreement with Bauer et al. [10, 21, 35], the Reverdin-Isham osteotomy has a slight impact on this angle, reporting an IMA mean improvement of about just 3°, again a better mean correction of about 8° and 15° for the DMAA and HVA, respectively. According to our experience, the efficacy in IMA correction is probably explained by the combined action between the three different surgical steps of the procedure. First, during the application of manual force to perform the lateral cortex osteoclasis at the step of the wedge closing, a minimum translation of the metatarsal head occurs (Fig. 6 B1–E1). It is known that distal osteotomies allow achieving proximally 1° of IMA correction for each millimetre of metatarsal head lateral translation [49, 50]. Second, the tenotomy of the adductor hallucis tendon and lateral capsulotomy contributes to the lateral movement of the first metatarsal axis, further decreasing its varus. Third, Isham in his original paper of 1991, stated that the average reduction of the IMA is especially noted when the procedure is performed in association with Akin osteotomy [19].

For the HVA, the effectiveness in angular value correction was 47.4%, with a preoperative mean value of 26.4° and 13.9° at the last follow-up, respectively. One of the objectives of distal osteotomies is to reduce the DMAA by a medial rotation of the metatarsal head. In the analysed sample, average correction efficacy was 46.1%; the mean preoperative angular value was 10.2° and 5.4° at the final follow-up. According to Coughlin [29], it is very important to correct DMAA, since a stable recovery can be achieved only by setting up the bone structure, re-orienting articular surfaces and re-equilibrating muscle forces of the first ray, avoiding the retraction of soft tissue and peri-articular adhesions. As reported in the literature [10, 24, 35, 39, 42], confirmation of the re-orientation of the forces on the muscle-ligamentous compartment was seen as restoration of the articular congruency and sesamoid compartment alignment.

Reverdin-Isham percutaneous osteotomy was a reliable procedure in correcting the different radiological parameters considered in this analysis, and our data are comparable with the reported angular corrections obtained with other percutaneous or open distal metatarsal osteotomies [13, 39, 42, 51]. Derotation of the metatarsal head (DMAA), and the anatomical reduction of the tibial sesamoid, necessary to prevent the recurrence of valgus [52], were all maintained until the last follow-up (Table 3). However, the results obtained in the correction of the HV severe deformities were less encouraging. In fact, the correction efficacy of the different single angles analysed, although high, was in some cases not sufficient to report them as in the normal range (Table 4). The six major complications of our series occurred in the severe forms, with an IMA greater than 15°. Hence, in accordance with Bauer et al. [10], we believe this is the angular value limit, beyond which the use of only Reverdin-Isham osteotomy as described is not recommended.

The first strength of this study is its nature: a prospective evaluation of a consistent group of 80 patients with the same fixed follow-up points. A 48-month follow-up can be considered a long follow-up period compared with previous published studies. Further, all operations and the post-operative controls were always performed in the same way by the same surgeon (C.B.). All clinical and radiographic data were collected and analysed separately by the same two independent investigators, who were not involved in the patients’ treatment and one not belonging to our unit. The main limitation of this study is the lack of a control group, which would be useful to compare the results of this percutaneous technique. However, as reported by several authors [15, 42, 44, 53], MIS includes different techniques, and the heterogeneity of the groups examined in various reports does not permit at present an effective comparison and clear conclusions. For these reasons, we believe that long-term follow-up with multicentre studies and randomized controlled clinical trials comparing Reverdin-Isham osteotomy outcomes to those of other percutaneous methods would provide useful information for the validity and reliability of MIS in the treatment of forefoot deformities.

Based on our experience in MIS with the first cohort of patients described in this report, we conclude that Reverdin-Isham and Akin percutaneous osteotomy in combination with previous exostosectomy and following lateral soft-tissue release is a safe, effective and reliable procedure for correction of mild-to-moderate symptomatic HV. Good results remained consistent at the midterm follow-up point. The most important aspects that should encourage the use of this percutaneous technique are its minimally invasive nature, the low number of complications, the absence of osteosynthesis, distal ankle block anaesthetic technique, early weight bearing and good cosmetic results with minimal surgical scars.