Interventional procedure overview of minimally invasive percutaneous surgical techniques with internal fixation for correcting hallux valgus
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Evidence summary
Population and studies description
This interventional procedures overview is based on 1,975 patients from 2 meta-analyses, 3 RCTs and 3 retrospective cohort studies (1 with propensity score matching) and 3 case series. Of these 1,975 patients, 680 patients had the minimally invasive percutaneous surgical technique with internal fixation (636 MIS Chevron osteotomy procedures, 44 fourth generation MIS transverse osteotomy Akin procedures, 47 Lapidus tarsometatarsal [TMT] fusion), and 303 had open osteotomy procedures (163 with open scarf Akin osteotomy, 140 with open Chevron osteotomy), 44 open Lapidus TMT fusion and 901 had MIS Reverdin Isham osteotomy (with no fixation). This is a rapid review of the literature, and a flow chart of the complete selection process is shown in figure 1. This overview presents 11 studies as the key evidence in table 2 and table 3, and lists 39 other relevant studies in table 5.
The countries where the procedures were carried out include Romania, Helsinki, Australia, Singapore, China, Austria, Switzerland, and the UK. The population is comprised of patients above 18 years with hallux valgus deformity:
mild deformity: HVA 15° to 20° or IMA 9° to 14°, or both
moderate deformity: HVA 20° to 40° or IMA 14° to 20°, or both
severe deformity: HVA 40° or above, or IMA 20° or above, or both.
The study designs include systematic review and meta-analyses, RCTs, retrospective cohort studies and case series. The follow up periods range from 1 to 5 years.
The meta-analysis comparing third generation PECA osteotomy with open scarf akin osteotomy (traditional open surgery) included only 3 studies (1 RCT and 2 cohort studies) with short term follow up (Ferreira 2021). Another meta-analysis compared 2 MIS techniques, MIS distal Chevron-Akin osteotomy (1 study) with MIS Reverdin-Isham osteotomy (no fixation, 14 studies). The quality of the included studies on MIS Reverdin-Isham osteotomy were low and only 7 studies were used in the meta-analysis. The MIS distal Chevron-Akin osteotomy was done by a single surgeon in 1 centre (Kaufmann 2021).
Two small RCTs (Dragosloveanu 2022, Kaufmann 2019 and 2022) compared third generation percutaneous MICA and open approaches for Chevron osteotomy (another traditional open surgery). Follow up in these studies ranged from 1 year (Dragosloveanu 2022) to 5 years (Kaufmann 2019 and 2022). All surgeries in both RCTs were done by a single foot and ankle surgeon. 17% (8/47) of patients dropped out of 1 RCT (2 were lost to follow up and 6 declined continuing in the study; Kaufmann 2019 and 2022). Another small RCT compared MIS scarf osteotomy with open scarf osteotomy. All procedures were done by a single foot and ankle surgeon in both groups. Lesser toe deformities were also treated in 50% of patients in both groups (Torrent 2021).
Two small retrospective cohort studies (Guo 2021, Tay 2022) compared percutaneous MICA and open chevron osteotomy. One of the small retrospective cohort studies compared percutaneous oblique osteotomy and internal fixation with open chevron osteotomy (Guo 2021) in 112 people. The retrospective propensity matched cohort study of 60 patients compared MICA with open scarf-akin osteotomy (Tay 2022).
Two case series (1 retrospective and 1 prospective study) assessed third generation MIS procedures (MICA and PECA). The retrospective study of 92 patients (126 consecutive feet) had more than 60 months follow up. The study was adequately powered and validated clinical outcome measures were used. But it lacked validated preoperative clinical PROMS. A 40% loss to follow up for radiographs at final follow up was reported (Lewis 2023a). The prospective case series was large (230 patients [333 feet]) and had 2 years follow up. All procedures were done by a single surgeon and validated measures were used to assess PROMs. In-depth analysis of adverse events were reported. There was a lack of long-term radiographic follow up (Lewis 2021).
One small prospective case series of 50 patients with a wide range of HV deformities reported on a fourth generation (META) MIS technique with short follow-up period. All procedures were done by a single surgeon (Lewis 2023b).
A retrospective study compared MIS TMT fusion (Lapidus procedure) with the open Lapidus procedure in a single-surgeon practice. The follow-up period was shorter in the MIS group compared with the open procedure (Vieira Cardoso 2022).
Half of the studies are observational studies with some source of bias. Non-validated outcome measure tools, such as the AOFAS and VAS were used in most studies.
Table 2 presents study details.
Study no. | First author, date country | Patients and sex (female: male) or gender (women: men) as reported by the study | Age | Study design | Inclusion criteria | Intervention | Follow up |
|---|---|---|---|---|---|---|---|
1 | Ferreira GF, 2020 Australia, Singapore, and Switzerland | N=235 feet with hallux valgus PECA group n=102 (89:13) Open SA osteotomy group n=133 (120:13) | PECA Mean 48 to 54 years open SA osteotomy mean 48 to 54 years | Systematic Review and meta-analysis (n=3 studies including 2 cohort studies and 1 RCT) | Hallux valgus diagnosis and surgical treatment by the open SA osteotomy and PECA techniques. | PECA osteotomy and open SA osteotomy | 6 months |
2 | Kaufmann G, 2021 Austria | N=950 patients MIS/percutaneous chevron osteotomy: 49 patients (57 feet) (52:5) MIS Reverdin-Isham osteotomy: 901 patients (1033 feet) (774: 60; 4 studies did not report). | MIS chevron osteotomy Mean 53 years MIS Reverdin-Isham group range from 12.5 to 61.5 years | Systematic review and meta-analysis 14 studies (7 included in meta-analysis). | Articles in English or Spanish, assessing MIS/percutaneous chevron distal /oblique osteotomy, MIS Reverdin-Isham method, with a minimum follow up of 6 months and presenting results in terms of clinical or radiological data were included. | MIS distal chevron osteotomy (1 case series of 49 patients-57 feet with mild to moderate HV deformity) 45 feet had phalangeal Akin osteotomy compared with MIS Reverdin-Isham method. | MIS chevron osteotomy mean follow up 58.9 (range 39.0 to 85.4) months. MIS Reverdin-Isham method minimum 6 to 60 months. |
3 | Dragosloveanu S, 2022 Romania/Helsinki | N=50 patients with moderate hallux valgus Percutaneous MIS chevron osteotomy group n=24 (24:0) OC osteotomy group n=26 (24:2) | MIS chevron osteotomy: 49±15 years OC osteotomy: 55±15 years | RCT | Patients older than 20 years old, when conservative treatment had failed, with moderate valgus deformity (HVA between 20 and 40 degrees and an IMA between 11 and 16 degrees) | Percutaneous MIS chevron osteotomy (MIS group) compared with OC osteotomy (OC group) | 1 year |
4 | Kaufmann G, 2019, 2020 Austria | N=47 patients with hallux valgus MIS chevron osteotomy n=25 feet (21:4) OC n=22 feet (19:3) | MIS chevron: 54±15.2 years OC: 47±14.3 years | RCT | Adults with hallux valgus who were scheduled to have distal chevron osteotomy between January 2012 and August 2013. In all nonoperative treatment had failed before surgery. | Percutaneous/MIS chevron osteotomy compared with OC osteotomy | 9 months (mean, 67.1 ± 6.1 months): 47 feet 5 years: 39 feet |
5 | Tay A, 2022 Singapore | N=60 patients with symptomatic hallux valgus MICA osteotomy group n=30 (21:9) Open SA osteotomy n=30 (26:4) | MICA: mean 51.7 years Open SA osteotomy: mean 52.7 years | Retrospective propensity score matched cohort Study | Patients who had primary, unilateral MICA osteotomy for symptomatic hallux valgus between 2016 and 2018 for persistent painful bunion with or without metatarsalgia after conservative treatment for at least 3 months. | MICA osteotomy screw compared with open SA osteotomy (control) Other concomitant procedures were also done in a few cases. | 24 months |
6 | Guo CJ, 2021 China | N=112 feet (99 patients with hallux valgus) MIS percutaneous oblique osteotomy (POO) group n=48 feet (41 patients; 45:3) OC osteotomy group n=64 feet (58 patients; 61:3) | MIS (POO) group: mean 60.9±12.2 years OC group: mean 60.6±9.69 years | Retrospective cohort study | Patients above 18 years with painful HV and failed conservative treatment; and HV correction had operative treatment via POO or open chevron osteotomy techniques. | Intervention: percutaneous oblique osteotomy (POO) and Control: OC osteotomy Akin osteotomy done in 50 (15 in POO and 35 in OC group) Weil osteotomy in 39 (16 in POO and 23 in OC group). | 2 years |
7 | Lewis T, 2023a Australia, 3 centres | N=92 patients with hallux valgus deformity (126 feet) (87:5) Included for analysis (n=53, 78 feet [51:2]) | Mean age: 60.4±11.5 | Retrospective observational study | People aged over 16 presenting with a painful hallux valgus deformity (HVA more than 15 degrees) who had isolated primary third-generation PECA with at least 60 months' follow up. | PECA by a single surgeon. No additional concomitant procedures were done. | Mean follow-up was 66.8±5.9 (range 60 to 88) months |
8 | Lewis T 2023b UK 2 centres | N=44 patients with hallux valgus deformity (n=47 feet [38:6]) | Mean 55.4±15.7 years | Prospective case series | People aged 16 and over, who had primary correction of hallux valgus, of all radiological severities and congruent and incongruent deformities, with first TMT joint instability or a diagnosis of generalised hyper-mobility, who had additional forefoot procedures. | Fourth-generation MIS only in 40% patients 60% had additional concomitant procedures (23 lesser toe proximal and distal interphalangeal joint deformity corrections, 3 bunionette corrections at little toe, 1 K-wire fixation for dislocated second toe, and 1 case of lesser metatarsal distal osteotomies for metatarsalgia in rheumatoid arthritis). | Mean 1.3±0.4 years (range 1.0 to 2.3). |
9 | Lewis T (2021) | N=230 patients (333 feet with hallux valgus deformity [214:16]) Mild: HVA 15 to less than 20 degrees and IMA 9 to 14 degrees 7.8% (n=25) Moderate: HVA 20 to less than 40 degrees and IMA 14 to less than 20 degrees 65.5% (n=209) Severe HVA 40 degrees or more and IMA 20 degrees or more 26.6% (n=85) | Mean age 55 years (range, 23.5 to 84.9 years) | Prospective case series | Patients over 16 who had primary correction of hallux valgus (of any deformity severity) were included. Patients who had additional forefoot procedures (such as hammer-toe correction or distal metaphyseal metatarsal osteotomy) were included. | Third-generation MICA by a single surgeon. 69 patients (138 feet) had bilateral procedures on same day. | Mean follow up was 2.5 years (range, 2.0 to 5.5 years) |
10 | Torrent J, 2021 Spain | N=58 patients MIS SA osteotomy group n=30 (28:2) Open SA osteotomy group n=28 (28:2) | MIS SA osteotomy: mean 60.7 years Open SA osteotomy: mean 64.2 years | RCT | Indication of scarf osteotomy as the treatment for HV deformity, failed conservative treatment for at least 6 months. | Minimally invasive scarf osteotomy compared with open scarf osteotomy | 21 (range, 12 to 38) months |
11 | Vieira Cardoso D 2022 Switzerland | N=91 patients MIS Lapidus procedure N=47 (43:4) Open Lapidus procedure N=44 (38:6) | MIS group mean 58 years Open group mean 62 years | Retrospective cohort study | Patients over 18 who had MIS (between 2018 to 2019) or open first TMT fusion surgical procedure (between 2015 to 2017) to treat moderate to severe hallux valgus deformities were reviewed. | MIS TMT fusion (Lapidus procedure) compared with open TMT fusion (Lapidus procedure) | MIS group mean 29 (range, 14 to 47) months Open group mean 82 (range, 31 to 82) months |
Procedure technique
All studies detailed their procedure technique with variations in surgical technique, implants placed and additional surgery. The most common approach used in 6 studies (Dragosloveanu 2022, Kaufmann 2019 and 2021, Guo 2021, Tay 2022, Lewis 2023a) was the third generation MIS percutaneous distal chevron osteotomy (also known as MICA/PECA techniques). It is an extra-articular metatarsal osteotomy that involves sliding manoeuvre of the first metatarsal head and internal fixation with at least 1 or 2 screws. Different screws were used in studies (such as headless cannulated screws with flat and square ends, and fully threaded MICA screws with a chamfered head design). MICA procedure with a new generation MICA screw was used in 1 of the studies (Tay 2022). Different fixation methods in different zones (such as dorsal-to-plantar) were used in studies. POO was used in 1 study to avoid excessive shortening of the first metatarsal and provide intrinsic stability (Guo 2021).
A fourth generation MIS surgery with a distal metaphyseal extra-articular transverse and akin osteotomy (META), combined with 3D reduction manoeuvre and fixed using 2 screws for early weightbearing and biomechanical stability was used in 1 study (Lewis 2023b).
MIS scarf osteotomy is another third generation extra-articular osteotomy used in 2 studies (Ferreira 2021, Torrent 2021), in which the osteotomy is fixed with 1 or 2 headless screws introduced through a dorsal percutaneous approach. The procedure was done under a midfoot nerve block and no tourniquet with the use of intraoperative fluoroscopy.
MIS Reverdin Isham osteotomy is another specific MIS hallux valgus correction technique used in 1 study as a comparator (Kaufmann 2021). This procedure involves an intra-articular medial based closing wedge osteotomy of the metatarsal head without addressing the IMA and without any internal fixation.
Two main traditional techniques assessed as comparators in included studies were OC osteotomy and open SA osteotomy. In OC osteotomy, a V shaped osteotomy was done through a 4 to 5 cm incision. In open SA osteotomy a Z-shaped diaphyseal osteotomy of the first metatarsal was usually done and needs fixation with 2 screws.
Another technique, the Lapidus procedure either as a MIS or open procedure was reported in 1 study. This involves removing the cartilage from the first tarsometatarsal joint (TMT) and the medial cuneiform, correcting the deformity and fusing of the bones by hardware.
In most of the studies, some patients had additional adjunct procedures such as Akin or Weil osteotomy together with hallux valgus correction.
Efficacy
Functional improvement
Five studies on MIS techniques (PECA or MICA) compared with open SA or OC osteotomy showed similar functional improvement at follow up, which ranged from 6 months to 5 years.
MICA or PECA compared with OC osteotomy
The RCT of 47 patients reported that the functional AOFAS score improved from baseline for both the MIS and OC osteotomy groups. The median score improved from 65 at baseline to 95 at 5 years in the MIS group, and from 66.5 to 95 in the OC osteotomy group. The difference between the groups was not statistically significant at any of the follow-up intervals (Kaufmann 2019, 2020).
The retrospective cohort study of 112 feet (99 patients) reported that the AOFAS HMI scores improved significantly in POO and OC osteotomy groups postoperatively (p<0.001). There was no statistically significant difference between the groups at 1 year (86.5 ± 10.7 for POO and 88.2 ± 10.8 for OC, p=0.40) and 2 years follow up (85.2 ± 13.8 for POO and 79.5 ± 23.7 for OC, p=0.66; Guo 2021).
The systematic review of 3 studies (n=235 feet) comparing PECA with open SA osteotomy reported that the mean difference in the AOFAS score between the groups was small (4.97 points 95% CI 3.55 to 6.39, p=0.14, I2=48%) at 6 months follow up (Ferreira 2021).
The RCT of 50 patients reported improvements in the AOFAS score for both MIS and OC osteotomy groups. There were no statistically significant differences between the groups, either before surgery (MIS group 65.7 ± 3.8 compared with OC group 61.4 ± 4.5; p=0.134), or at 6 months follow up (MIS group 85.6 ± 4.1 compared with OC group 79.4 ± 3.6 p=0.125; Dragosloveanu 2022).
MIS scarf osteotomy compared with open scarf osteotomy
The RCT of 58 patients compared MIS scarf osteotomy (n=30) with open scarf osteotomy (n=28). It reported that in both groups the AOFAS scores showed a significant improvement at final follow up (mean 21 months) compared with preoperative scores (MIS scarf group from 41 to 84 and open scarf group from 39 to 82, p<0.001) without significant differences between groups (Torrent 2021).
Pain improvement
Six studies on MIS techniques (PECA or MICA) compared with open SA or OC osteotomy showed similar improvement in pain at follow up, which ranged from 6 months to more than 5 years.
MICA or PECA compared with OC osteotomy
The RCT of 47 patients reported that VAS pain score improved from baseline for both the MIS and OC osteotomy groups but was not significantly different between the groups at any of the follow-up intervals (6 weeks [p=0.95], 12 weeks [p=0.14], 9 months [0.74]), and 5 years (p=0.32) follow up (Kaufmann 2019 and 2020).
In the retrospective observational study of 92 patients (126 feet) who had treatment with PECA, an analysis of data in 53 patients (78 feet) reported a mean postoperative VAS pain score (ranging from 0 to 10, where 0 is the best possible score) of 6.3 SD 14.9 at more than 60-month follow up (Lewis 2023a).
In the prospective case series of 233 patients (333 feet), the quality-of-life PROMs analysed in 200 patients (n=292 feet) reported that the VAS pain score improved from 31.4 SD 22.7 preoperatively to 8.4 SD 16.4 at 24 months follow up (p<0.001; Lewis 2021).
The propensity matched cohort study of 60 patients compared MICA with open SA osteotomy. It reported that the first 24-hour postoperative VAS score was significantly lower in the MICA group compared with the open SA group (2.0 SD 2.0 compared with 3.4 SD 2.6, p=0.029). But there was no significant difference in clinical or radiological outcomes between the groups at 6 months (p=0.990) and 24 months (p=0.290; Tay 2022).
The retrospective cohort study of 112 feet (99 patients) reported that the VAS scores in the POO group during the follow-up period were 2.00 SD 0.98 at 2 weeks, 2.00 SD 0.99 at 1 year and 1.55 SD 1.11 at 2 years. In the OC group the VAS scores were 5.51 SD 1.45 at 2 weeks, 2.56 SD 2.88 at 1 year and 2.56 SD 2.88 at 2 years. The VAS scores between POO and open groups showed no statistically significant difference at 1-year (p=0.53) and 2-year (0.37) follow up. But the POO group showed statistically significantly lower VAS scores 2 weeks after surgery (p<0.001; Guo 2021).
The RCT of 50 patients found significant improvements in the VAS scores for MIS and OC osteotomy groups. The VAS showed significantly better postoperative results for the MIS group at discharge (2.5 SD 0.8 compared with 4.5 SD 1.4, p<0.001), 3 weeks (1.4 SD 0.5 compared with 2.8 SD 0.9, p<0.001), 6 weeks (0.4 SD 1 compared with 2.0 SD 0.8, p<0.001), and 6 months (0.2 SD 0.8 compared with 0.8 SD 0.6, p=0.004). At 12 months, the pain level was comparable between both groups (0.2 SD 0.6 compared with 0.4 SD 0.7, p=0.285; Dragosloveanu 2022).
The systematic review of 3 studies (n=235 feet) compared PECA with open SA osteotomy. It reported that the mean difference in the VAS pain scale (ranging from 1 to 10) between the groups was -1.68 points (95% CI -2.09 to -1.27, p<0.01, I2=87%; 2 studies) 1 day after surgery. The mean difference at last clinical visit decreased between the groups (SMD-0.14 points, 95% CI -0.49 to 0.20, p=0.81, I2=0%; 3 studies; Ferreira 2021).
MIS scarf osteotomy compared with open scarf osteotomy
The RCT of 58 patients comparing MIS scarf osteotomy (n=30) with open scarf osteotomy (n=28) reported that the mean postoperative VAS for pain at 24 hours was significantly lower in the MIS scarf group compared with the open scarf group (2.3 compared with 3.6, p=0.03; Torrent 2021).
Range of motion
The RCT of 47 patients reported no significant differences in range of motion of the first metatarsophalangeal joint (categorised into 3 classes: less than 30 degrees, 30 to 70 degrees, and more than 75 degrees) between the MIS and OC osteotomy groups at all follow-up periods (6 weeks, p=0.075; 12 weeks, p=0.653; 9 months, p=0.910; and 5 years, p=0.496; Kaufmann 2019 and 2020).
Quality of life
Two studies on MIS techniques (MICA or POO) compared with open SA or OC osteotomy showed similar improvement in quality of life at follow up.
A retrospective cohort study of 112 feet (99 patients) compared POO and OC osteotomy. It reported that the clinical foot-specific postoperative MOXFQ scores in all domains (walking or standing, social interaction and pain) significantly improved in both groups. But there was no significant difference in the improvement of any domain between POO and open groups at 2-year follow up (Guo 2021).
The propensity matched cohort study of 60 patients compared MICA and open SA osteotomy. It reported improvement in both the mean SF-36 PCS scores (from 40.9 SD 9.3 to 50.6 SD 9.1, p<0.001) and the mean SF-36 MCS scores (from 56.8 SD 10.6 to 56.0 ± 10.7, p<0.001) at 24 months follow up in the MICA group. The scores also improved for the scarf osteotomy group (mean SF-36 PCS from 43.9 SD 9.7 to 51.9 SD 7.1, p<0.001; and mean SF-36 MCS from 54.8 SD 10.3 to 55.2 SD 11.1, p<0.001). But the scores were not significantly different between the groups (PCS p=0.538, MCS p=0.756; Tay 2022).
In the retrospective observational study of 92 patients (126 feet) who had treatment with PECA, an analysis of data in 53 patients (78 feet) reported that the clinical foot-specific mean MOXFQ index score (where 0 is the best possible score) at more than 60-month follow-up was 10.1. The mean general health-related quality of life PROM (assessed using EuroQoL-5D-5L: EQ-VAS, where 100 is the best possible score) at more than 60 month follow-up was 92.0 (Lewis 2023).
In the prospective case series of 233 patients (333 feet), the quality-of-life PROMs was analysed in 200 patients (n=292 feet). It reported significant improvement in MOFXQ scores in each domain (reduced from 44.5 SD 21.0 preoperatively to 9.4 SD 15.8 at 24 months for pain (p<0.001), from 38.7 SD 23.4 to 6.5 SD 14.6 for walking and standing (p<0.001), and from 48.0 SD 22.3 to 6.6 SD 13.5 for social interaction (p<0.001); EQ-5D-5L score improved from preoperative mean 0.75 SD 0.14 to 0.90 SD 0.13 at 24 months (p<0.001) with the exception of the EQ-VAS (from preoperative score mean 83.5 SD 14.9 to 84.2 SD 16.9 at 24 months, p=0.563; Lewis 2021).
In the prospective case series of 50 patients who had fourth generation MIS with metaphyseal extraarticular transverse and akin osteotomy (META) there was a significant improvement in all MOXFQ domain scores, with the index domain improving from 53.4 to 13.1 (p<0.001). There was also a statistically significant improvement in general health-related quality of life EQ-5D-5L index and EQ-VAS scores (p<0.001; Lewis 2023).
Patient satisfaction
Two studies on MIS techniques (MICA or POO) compared with open SA or OC osteotomy showed similar patient satisfaction rates at follow up.
In the RCT of 47 patients, patient satisfaction (measured using a scale ranging from very satisfied to not satisfied) was comparable in both MIS and OC osteotomy groups at 9 months follow up (very satisfied: 62.5% compared with 70%, p=0.736). At 5 years, 89% of the patients in the MIS and 70% in the OC osteotomy group were very satisfied. Two patients in OC osteotomy group, reported poor satisfaction. One of these patients had developed partial osteonecrosis of the lateral metatarsal head, and 1 had a recurrence of hallux valgus (Kaufmann 2019 and 2020).
The propensity matched cohort study of 60 patients comparing MICA and open SA osteotomy reported that satisfaction rates were similar at 6 months (MICA group 87% [26/30]) compared with the open SA group 73% [22/30], p=0.197) and 24 months follow up (MICA group 80% [24/30] compared with the open SA group 87% [26/30], p=0.488; Tay 2022).
In the retrospective observational study of 92 patients (126 feet) who had treatment with PECA, an analysis of data in 53 patients (78 feet) reported that at more than 60 months follow up, 77% patients were highly satisfied and 23% patients were satisfied with the procedure (Lewis 2023).
Recurrence
In the RCT of 37 patients comparing MIS chevron osteotomy with OC osteotomy, 8% (2/25) of patients in the MIS group (25) and 9% (2/22) of patients in the OC group had recurrence of hallux valgus with an HVA of less than 25 degrees. One patient in the OC group had recurrence of hallux valgus with an HVA of more than 30 degrees (Kaufmann 2019 and 2021).
The prospective case series of 230 patients (333 feet) reported symptomatic recurrent HV after the procedure in 3 feet (0.9%). Two of these were because of under-correction by the chevron osteotomy and failure of the akin osteotomy screw because of cutout. The third was because of soft tissue stretching over a prolonged time (Lewis 2021).
In the retrospective observational study of 92 patients (126 feet) who had treatment with PECA, an analysis of data in 53 patients (78 feet) reported a radiographic recurrence rate (defined as HVA more than 15 degrees) of 8% (6/78 feet) at more than 60 months follow up. Of these, only 1 foot had an HVA more than 20 degrees and 3 of the 6 feet had a severe preoperative deformity (HVA more than 40 degrees; Lewis 2023).
Recurrences of HVA (no revision surgery) was reported in 7% (2/30) of patients in the MIS scarf osteotomy group in the RCT of 58 patients (Torrent 2021).
In the retrospective cohort study of 91 patients who had TMT Lapidus procedure, deformity recurrence (needing revision) was reported in 2 patients in the MIS group and 3 patients in the open group (p=0.617; Vieira Cardoso 2022).
Hallux joint angle correction
There are normal for X-ray measurements: HVA less than 15 degrees; IMA less than 9 degrees; and DMAA less than 10 degrees.
Nine studies on MIS techniques (MICA/PECA/META) reported statistically significant improvement in HVA, IMA and DMAA from preoperative values at follow up. Six of these studies compared MIS techniques (PECA or MICA) with open SA or OC osteotomy and showed similar radiographic correction.
MICA or PECA compared with OC osteotomy
A systematic review of 3 studies (n=235 feet) compared PECA osteotomy (n=102) with open SA osteotomy (n=133). It reported that the final mean difference in the HVA was 0.80 degrees (95% CI -1.07 to -0.52, p=0.03, I2=70%) and the mean difference in the IMA was 0.53 (95% CI -0.93 to -0.13, p<0.01, I2=93%), at the last radiographic evaluation (Ferreira 2021).
A RCT of 50 patients comparing percutaneous MIS chevron osteotomy (n=26) with OC osteotomy (n=26) reported improvements in both groups regarding the IMA and HVA at 12 months follow up. But, it did not find any statistically significant differences between the groups (IMA: 7.2 SD 1.8 compared with 6.4 SD 1.5; p=0.093; HVA: 8.8 SD 3.1 compared with 8.9 SD 2.3; p= 0.896; Dragosloveanu 2022).
A RCT of 47 patients comparing MIS chevron osteotomy (n=25) with OC osteotomy (n=22) reported statistically significant correction of the hallux deformity using both techniques. The IMA improved from 14 to 6.8 degrees in the MIS group and from 15.1 to 5.8 degrees in the OC group. The HVA improved from 26.4 to 6.9 degrees in the MIS group and from 28.3 to 8.5 degrees in the OC group. No statistically significant differences were seen between the groups at all follow-up periods (6 weeks, 12 weeks, 9 months and at 5 years; Kaufmann 2019 and 2020).
A propensity matched cohort study of 60 patients comparing MIS chevron akin osteotomy (MICA) with open SA osteotomy reported that HVA improved from 23.5 to 7.7 degrees postoperatively, and IMA improved from 13.5 to 7.5 degrees postoperatively for the MICA group. For the open SA osteotomy group, HVA improved from 23.7 to 9.3 degrees postoperatively, and IMA improved from 13.6 to 7.8 degrees postoperatively. There was no statistically significant difference between the groups (Tay 2022).
A retrospective cohort study of 112 feet (99 patients) compared percutaneous oblique osteotomy (POO) and OC osteotomy. It reported that the HVA in the POO group reduced from 35.9 SD 10.0 degrees preoperatively to 12.5 SD 2.22 degrees at 1 year (p<0.05) and to 17.9 SD 9.31 degrees at 2 years follow up (p<0.05). In the OC group, HVA decreased from 34.3 SD 8.85 degrees preoperatively to 14.1 SD 6.78 degrees at 1 year (p<0.05) and 14.8 SD 7.83 degrees at 2 years follow up (p<0.05). Similar results were reported for IMA at follow-up periods (p<0.05). When comparing both groups, HVA (at 1 year, p=0.12 and 2 years, p=0.06) and IMA (at 1 year, p=0.14 and 2 years, p=0.95) showed similar results (Guo 2021).
In a retrospective observational study of 92 patients (126 feet) who had treatment with PECA, an analysis of data in 53 patients (78 feet) reported a change in HVA from mean 28.2 degrees preoperatively to 7.8 degrees at more than 60 months follow up (mean change −20.3 SD 7.0; p<0.001) and change in the IMA from mean 12.8 degrees preoperatively to 6.0 degrees at more than 60 months follow up (mean change −6.8 SD 3.0, p<0.001; Lewis 2023).
In a prospective case series of 233 patients (333 feet), radiographic outcomes analysed in 200 patients (n=319 feet) reported significant reduction in the IMA (from mean preoperative 15.3 SD 3.6 to 5.7 SD 3.2 degrees at 6 weeks, p<0.001) and HVA (from mean preoperative 32.9 SD 10.2 to 8.7 SD 5.2 at 6 weeks, p<0.001; Lewis 2021).
In a prospective case series of 50 patients who had fourth generation MIS with metaphyseal extraarticular transverse and akin osteotomy (META) there was a significant improvement in HVA (32.7 to 7.9 degrees, p<0.001), IMA (14.0 to 4.2 degrees, p<0.001) and DMAA (18.5 to 5.6 degrees, p<0.001) at mean follow up of 1.53 SD 0.51 years (Lewis 2023).
MIS scarf osteotomy compared with open scarf osteotomy
A RCT of 58 patients comparing MIS scarf osteotomy (n=30) with open scarf osteotomy (n=28) reported that radiologic measurements were similar in both groups at final follow-up (mean 21 months: HVA p=0.08, IMA p=0.79, and DMAA p=0.80) but showed significant improvement from preoperative measures (Torrent 2021).
MIS distal chevron osteotomy compared with MIS Reverdin-Isham osteotomy
A systematic review and meta-analysis comparing MIS distal chevron osteotomy with MIS Reverdin-Isham osteotomy reported that radiographic outcomes were significantly better in the MIS chevron osteotomy group (IMA p<0.05, HVA and DMAA p<0.05; Kaufmann 2021).
MIS Lapidus procedure compared with open Lapidus procedure
A retrospective cohort study of 91 patients comparing first tarsometatarsal (TMT) fusion (Lapidus procedure) using MIS (n=47) and open (n=44) techniques reported that radiographic outcomes (IMA, HVA, DMAA) significantly improved from preoperative measures at postoperative follow up (mean 29 months for MIS and 82 months for open group). When compared between both the groups, the IMA was significantly lower in the open group (4.8 SD 3.6 degrees compared with 6.4 SD 3.2 degrees, p<0.05; Vieira Cardoso 2022).
Safety
Complications
The systematic review of 3 studies (n=235 feet) comparing PECA with open SA osteotomy reported a higher rate of complications in the PECA group (RR 1.51, 95% CI 0.80 to 2.86, p=0.36, I2=3%). Complications with the screws were reported in the PECA group, some of which were removed (actual number not reported). Complications in the open SA group included metatarsalgia and wound complications (Ferreira 2021).
The propensity matched cohort study of 60 patients comparing MICA and open SA osteotomy reported that there were no complications in either group. All cases achieved complete fusion of the osteotomy at the last radiological evaluation (Tay 2022).
The retrospective case study of 112 feet (99 patients) reported there was no statistical significance between the POO and OC osteotomy group in terms of complications rates (8.3% [4/48] compared with 12.5% [8/64], p=0.48; Guo 2021).
The prospective case series of 230 patients (n=333 feet) reported an overall complication rate of 21% at 24 months follow up. Grade 3 complications needing intervention or hospital admission were reported in 7.8% (n=26) of patients. These include hardware problems (prominent screws in 8, bone screw interface failure [fracture/screw cutout] in 6), delayed union or malunion, or no union, in 4, prominent bone in 4, deep infection in 4 cases. Grade 2 complications needing no additional intervention or hospital admission were reported in 6% (n=20) of patients. These include additional intraoperative fixation in 6, intraoperative conversion to open surgery in 2, symptomatic osteotomy site displacement in 1, symptomatic delayed union in 1, transfer metatarsalgia in 3, and recurrence in 3 cases (Lewis 2021).
The RCT of 58 patients comparing MIS scarf osteotomy with open scarf osteotomy reported that there were no major complications in either group (Torrent 2021).
The retrospective study of 91 patients who had first TMT fusion (Lapidus procedure) using MIS or open techniques reported that overall complications were higher in the open group compared with the MIS group, but this was not significantly different (5 in MIS group compared with 12 in the open group, p=0.42; Vieira Cardoso 2022).
Metatarsalgia
Metatarsalgia after 6 months was reported in 1 patient in the OC osteotomy group (n=26) in the RCT of 50 patients. Shortening of the first metatarsal during the osteotomy could be the reason for this complication (Dragosloveanu 2022). Two cases of second metatarsalgia were also reported in the OC osteotomy group (n=64 feet) in the retrospective cohort study of 99 patients (with 112 feet; Guo 2021).
Reoperations and hardware removal
Soft tissue irritation and pain caused by screw prominence (needing hardware removal after 3 months) was reported in 13% (3/24) of patients in the MIS osteotomy group compared with 1 patient in the OC osteotomy group (n=26) in the RCT of 50 patients. Authors state that the reason for tissue irritation could be the oblique insertion and slight protrusion of the screw head (Dragosloveanu 2022).
In the RCT of 47 patients, substantial soft-tissue irritation caused by the Kirschner wire needing removal was reported in 64% (16/25) of patients in the MIS group, whereas screw removal was needed in 18% (4/22) of patients in the OC osteotomy group. In response to these results, authors recommended using a cannulated oblique-headed compression screw for fixation during MIS chevron osteotomy (Kaufmann 2019 and 2020). Screw removal because of irritation after 3 months was reported in 1 patient in the POO group (n=41 patients, 48 feet) in the retrospective cohort study of 99 patients (Guo 2021).
Screw removal because of irritation and screw prominence or dorsal protrusion was reported in 1 patient in the MIS scarf osteotomy group (n=30) in the RCT of 58 patients (Torrent 2021).
Reoperations for removal of prominent screws were reported in 4% (5/126) of patients at more than 60 months follow up in the retrospective observational study of 92 patients (126 feet) who had treatment with PECA (Lewis 2023a). The all-cause screw-removal rate needing revision was 6.3% (n=21 feet) in the case series of 230 patients (n=333 feet) at 2 years follow up (Lewis 2021).
One patient in the POO group (n=41) had a revision surgery at day 6 because of screw displacement after initial weight-bearing on the first day after surgery in the retrospective cohort study of 99 patients (Guo 2021).
Surgery for hardware removal was reported in 6 patients in the MIS group (at mean 33.5 months) and 3 patients in the open group (at mean 85 months, p=0.487) in the retrospective study of 91 patients who had the TMT Lapidus procedure (Vieira Cardoso 2022).
Wound complications and non-union
Wound healing and non-union rates were higher in the open group compared with the MIS group in the retrospective study of 91 patients who had the TMT Lapidus procedure (wound healing: 0 in the MIS group compared with 4 in the open group, p=0.051; non-union (needing revision): 0 in MIS group compared with 4 in the open group, p=0.051; Vieira Cardoso 2022).
Exposure to radiation
The systematic review of 3 studies (n=235 feet) compared the percutaneous chevron akin (PECA) with open SA osteotomy. It reported that exposure to radiation during the surgical procedure was higher in the PECA group, with a mean of 35.53 seconds (95% CI 31.75 to 35.31, p<0.01, I2=87%; Ferreira 2021).
The RCT of 50 patients reported that the average radiological screen time was significantly longer for the MIS group (15.5 SD 5.6 seconds) compared with the OC osteotomy group (1.8 SD 3.8 seconds; p<0.001; Dragosloveanu 2022).
The RCT of 58 patients comparing MIS scarf osteotomy with open scarf osteotomy reported that radiation exposure was 14 times higher in the MIS scarf group compared with the open scarf group (mean 34 mGy/cm2 compared with 2.4 mGy/cm2, p<0.001; Torrent 2021).
Other events
Other events such as paraesthesia of the medial of first metatarsal (n=1), stiffness of the first MTP joint (n=1), flexor hallucis longus (FHL) tendon injury (n=5), superficial cellulitis (n=15), delayed wound healing (n=2) and transient neurapraxia (n=3) were reported in the MIS groups in the included studies. Neurovascular complications and hardware-related pain were reported in both the MIS and open technique groups in the retrospective study of 91 patients who had first TMT Lapidus procedure (Vieira Cardoso 2022). One of the patients in the OC osteotomy group had developed partial osteonecrosis of the lateral metatarsal head (Kaufmann 2019 and 2021).
Anecdotal and theoretical adverse events
Expert advice was sought from consultants who have been nominated or ratified by their professional society or royal college. They were asked if they knew of any other adverse events for this procedure that they had heard about (anecdotal), which were not reported in the literature. They were also asked if they thought there were other adverse events that might possibly occur, even if they had never happened (theoretical).
They listed the following anecdotal adverse events:
patient dissatisfaction because of recurrent deformity.
They listed the following theoretical adverse events:
avascular necrosis of the metatarsal head
non-union due to the large corrections
tendon damage
complex regional pain syndrome.
Five professional expert questionnaires for this procedure were submitted. Find full details of what the professional experts said about the procedure in the specialist advice questionnaires for this procedure.
Validity and generalisability
Studies on percutaneous techniques with internal fixation only have been considered in this overview of evidence. Variation in osteotomy techniques, hardware/cutting tools, insertion aids, fixing devices (screws, wires, sutures) were reported as they have been changed with time. Studies compared different MIS procedures to different conventional open surgical procedures. Few small RCTs performed compared different surgical procedures.
Follow-up in studies ranged from 1 to 5 years.
In all studies correction was indicated after failure of conservative treatment with progressive deformity.
Studies included patients with mild (HVA 15 to less than 20 degrees, IMA 9 to 14 degrees), moderate (HVA 20 to less than 40 degrees, IMA 14 to less than 20 degrees) and severe (HVA 40 degrees or more or IMA 20 degrees or more) hallux valgus deformity. Small case series for correction of severe hallux valgus deformity also demonstrated deformity correction and significant improvements in clinical outcomes 3 years following surgery (these studies are included in table 5).
There is a learning curve with percutaneous hallux valgus surgery. There is some published evidence suggesting that adequate training and experience is required (these studies are in table 5).
Procedures were done only by consultant trauma and orthopaedic surgeons sub-specialising in foot and ankle surgery.
Patients who have this procedure should be entered into the national BOFAS Registry via the Adult Foot and Ankle pathway. This dataset collects PROMS on both open and MIS techniques for hallux valgus correction. One specialist adviser stated that 18% (137/766) of procedures logged onto the database were minimally invasive metatarsal osteotomies.
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