Gender differences in early functional recovery after minimally invasive distal transverse metatarsal osteotomy - Akin Osteotomy (MITA) for hallux valgus: a propensity-matched study of 300 cases

Abstract

Background

Evidence regarding sex-based differences in outcomes after minimally invasive distal transverse metatarsal osteotomy - Akin osteotomy (MITA) for hallux valgus remains limited. This study compared clinical and radiographic outcomes and complication rates between male and female feet using a propensity score–matched cohort.

Methods

This retrospective study included 300 feet (150 male and 150 female) that underwent MITA. Male and female feet were matched using propensity scores based on age, preoperative hallux valgus angle (HVA), and preoperative intermetatarsal angle (IMA). Clinical outcomes were assessed using the visual analog scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, and Manchester–Oxford Foot Questionnaire (MOXFQ). Radiographic outcomes included HVA, IMA, and bony foot width. Assessments were performed preoperatively, at 3 months postoperatively, and at 1 year.

Results

After propensity matching, baseline age (53.6 vs. 53.8 years), HVA (31.2° vs. 31.1°), and IMA (14.2° vs. 14.2°) were comparable between groups. Preoperatively, male feet showed worse clinical status, with lower AOFAS scores (66.6 ± 13.5 vs. 69.7 ± 10.7; p = 0.03), despite similar radiographic deformity. At 3 months postoperatively, male feet showed better early clinical outcomes, including lower VAS pain scores (0.2 ± 0.4 vs. 0.5 ± 0.8; p < 0.001), higher AOFAS scores (91.2 ± 2.0 vs. 90.3 ± 3.0; p = 0.002), and lower MOXFQ pain scores (12.0 ± 6.0 vs. 16.0 ± 10.1; p < 0.001). At 1 year, clinical outcomes were comparable between groups. Radiographic correction of HVA and IMA was similar between groups at both 3 months and 1 year. Complication rates were low and comparable between groups.

Conclusions

Male feet undergoing MITA present with worse baseline functional impairment but show greater early functional recovery, with clinical and radiographic outcomes comparable to those of female feet at 1 year. These findings suggest that sex may influence early recovery patterns, whereas 1-year clinical and radiographic outcomes appear comparable between male and female feet.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-026-10023-8.

Background

Hallux valgus is a common forefoot deformity characterized by lateral deviation of the hallux and medial deviation of the first metatarsal, often leading to pain, functional impairment, and difficulty with footwear. Epidemiologic studies and systematic reviews have consistently demonstrated that hallux valgus is more than twice as prevalent in women as in men, with reported pooled prevalence estimates of approximately 23%–30% in women and 11%–13% in men [1, 2]. Large population-based data further suggest that female sex is independently associated not only with higher prevalence but also with greater radiographic severity of deformity [3].

Despite this clear sex disparity in prevalence, evidence regarding sex-based differences after hallux valgus surgery remains limited. Most surgical outcome studies have predominantly included female patients, and previous studies evaluating the effect of sex on hallux valgus surgery have reported inconsistent findings. Some studies have suggested inferior clinical outcomes or higher complication rates in male patients, whereas others have found no clinically meaningful sex-related differences after adjustment for baseline deformity severity and patient characteristics [4, 5].

Since the early percutaneous distal metatarsal osteotomy described by Isham, minimally invasive surgery (MIS) for hallux valgus has evolved with improved fixation and biomechanical stability [6]. Recent meta-analytic evidence suggests that MIS can achieve clinical and radiographic outcomes comparable to those of open procedures [7]. Minimally invasive distal transverse metatarsal osteotomy–Akin osteotomy (MITA) is a fourth-generation MIS technique that emphasizes multiplanar correction through a distal transverse osteotomy stabilized with rigid screw fixation. Similar transverse osteotomy-based MIS techniques, including minimally invasive transverse distal metatarsal osteotomy (MITO) and metaphyseal extra-articular transverse and Akin osteotomy (META), have demonstrated favorable early clinical and radiographic outcomes [8, 9]. However, previous reports, including our large-cohort MITA study, primarily evaluated overall outcomes and did not specifically address whether patient sex influences postoperative results [10].

Therefore, this study aimed to compare clinical outcomes, radiographic correction, and complication profiles between male and female feet following MITA using a propensity score–matched, foot-based cohort, with particular attention to changes over predefined postoperative time points. We hypothesized that when baseline deformity severity is adequately matched, postoperative outcomes after MITA would not differ significantly between male and female patients.

Methods

This retrospective cohort study included consecutive feet that underwent minimally invasive distal transverse metatarsal osteotomy–Akin osteotomy (MITA) for symptomatic hallux valgus between March 23, 2020, and October 18, 2024. During the study period, a total of 2,710 feet underwent MITA, including 318 male and 2,392 female feet.

For outcome analysis, feet were included if preoperative and postoperative clinical and radiographic data were available and the minimum follow-up duration was 1 year. Feet with incomplete clinical or radiographic data, follow-up shorter than 1 year, revision hallux valgus surgery, or severe hallux rigidus requiring additional first metatarsophalangeal joint procedures were excluded. After applying the minimum follow-up and data availability criteria, 1,415 feet were available for outcome analysis, comprising 150 male and 1,265 female feet.

Inflammatory arthritis was not used as a predefined exclusion criterion in the original cohort. Patients with rheumatoid arthritis were included when MITA was performed for symptomatic hallux valgus as the primary surgical indication. Lesser-toe deformities or other associated forefoot pathologies were not considered absolute exclusion criteria when MITA was performed as the primary corrective procedure for hallux valgus. Concomitant forefoot procedures, including Weil osteotomy for metatarsalgia or claw toe correction, were performed when clinically indicated; however, these procedures were not used as selection criteria and were not separately stratified in the present analysis.

Because of the marked imbalance in sex distribution, a matched cohort was created for comparative analysis. Propensity score matching was performed using a nearest-neighbor approach without replacement. Matching variables included age, preoperative hallux valgus angle, and preoperative intermetatarsal angle. From the 1,265 female feet available for outcome analysis, 150 female feet were selected to match the 150 male feet, resulting in a final study cohort of 300 feet. The overall process of patient selection, exclusion, and propensity score matching is summarized in Fig. 1. Covariate balance before and after propensity score matching was assessed using standardized mean differences (SMDs) for all matched covariates. An absolute SMD of less than 0.1 was considered to indicate adequate balance.

Fig. 1.

Flow diagram of patient selection and study cohort formation. After applying the inclusion/exclusion criteria and propensity score matching based on age, preoperative HVA, and preoperative IMA, 300 feet, including 150 male and 150 female feet, were included in the final matched cohort. MITA, minimally invasive distal transverse metatarsal osteotomy–Akin osteotomy; HVA, hallux valgus angle; IMA, intermetatarsal angle; HV, hallux valgus; RA, rheumatoid arthritis

All procedures were performed by two foot and ankle surgeons under C-arm fluoroscopic guidance using the same standardized minimally invasive distal transverse metatarsal osteotomy–Akin osteotomy (MITA) technique, as previously described [11]. Through a small medial stab incision, a distal transverse osteotomy of the neck of the first metatarsal was created using a Shannon burr after subperiosteal dissection. The distal fragment was translated laterally and rotationally corrected under fluoroscopic control, followed by percutaneous fixation with two 3.5-mm cannulated screws. Resection of the medial eminence was then performed using a powered rasp system, and an Akin osteotomy of the proximal phalanx was subsequently performed through a separate medial stab incision and fixed with a single 3.0-mm screw to optimize hallux alignment. Percutaneous lateral soft-tissue release was not routinely performed. It was performed only selectively in rare cases when adequate hallux alignment could not be achieved after osteotomy-based correction alone, and was not separately analyzed in this study.

Postoperatively, immediate weight-bearing as tolerated was permitted for all operated feet using a postoperative shoe with a rigid outsole for four weeks. After wound healing, typically at approximately two weeks postoperatively, a corrective soft orthosis was applied and maintained until six weeks after surgery. Planned implant removal was generally performed at approximately 3 months postoperatively according to our institutional protocol. Clinical and radiographic healing was assessed before implant removal, and removal was postponed in cases with delayed union or insufficient radiographic consolidation. The same surgical technique and postoperative management protocol were applied to all cases regardless of sex.

Radiographic evaluations were performed preoperatively, at three months postoperatively, and at final follow-up of approximately one year (Fig. 2). Radiographic parameters included the hallux valgus angle (HVA) and intermetatarsal angle (IMA), which were measured on standardized weight-bearing anteroposterior foot radiographs according to the angular measurement guideline of the American Orthopaedic Foot & Ankle Society [12]. The HVA was defined as the angle between the longitudinal axis of the first metatarsal and the longitudinal axis of the proximal phalanx, and the IMA was defined as the angle between the longitudinal axes of the first and second metatarsals. Bony foot width was defined as the maximal transverse distance between the medial cortex of the first metatarsal head and the lateral cortex of the fifth metatarsal head on standardized weight-bearing anteroposterior radiographs, as previously described, and was measured in millimeters (Fig. 3) [13].

Fig. 2.

Serial weight-bearing anteroposterior radiographs of the foot in a 59-year-old male patient showing A preoperative, B postoperative at 3 months prior to screw removal, and C postoperative at 19 months after surgery

Fig. 3.

Radiographic measurements of the foot: A Hallux valgus angle, B Intermetatarsal angle, and C Bony foot width. Reproduced from Lee et al. [10] under the terms of the Creative Commons Attribution License

Clinical outcomes were assessed using the visual analog scale for pain [14], the American Orthopaedic Foot and Ankle Society hallux metatarsophalangeal–interphalangeal score [15], and the Manchester–Oxford Foot Questionnaire, including the pain, walking, and social interaction subscales [16]. Clinical and radiographic assessments were performed at the same postoperative time points.

Underlying diseases, including hypertension, diabetes mellitus, dyslipidemia, and rheumatoid arthritis, were recorded on a patient-based basis. Postoperative complications and outcomes were analyzed on a foot-based basis, and bilateral cases were included when both feet met the eligibility criteria. Although radiographic outcomes and pain-related scores were assessed for each operated foot, functional patient-reported domains, particularly MOXFQ walking and social interaction, may have been influenced by bilateral symptoms or patient-level factors.

Postoperative complications were identified through chart review and graded using a Clavien–Dindo–based framework adapted for orthopaedic and foot-and-ankle surgery. Complications were categorized into three grades according to the level of treatment required: Grade 1 events did not result in any deviation from routine postoperative follow-up, Grade 2 events required additional treatment but did not require further surgical intervention or unplanned hospital admission, and Grade 3 events required surgical intervention and/or unplanned hospital admission [17–19]. To ensure transparent reporting and comparability, complication definitions and event lists were organized with reference to prior orthopaedic reliability work and the foot-and-ankle–specific reporting recommendations, and were harmonized with those used in our prior large-cohort MITA report [10].

Continuous variables were expressed as means with standard deviations and categorical variables as frequencies and percentages. Between-group comparisons were performed using the independent-samples t-test or the chi-square test, or Fisher’s exact test as appropriate.

To complement p-values, effect sizes for between-sex comparisons were calculated using Cohen’s d and presented as absolute values. Cohen’s d values of approximately 0.2, 0.5, and 0.8 were interpreted as small, moderate, and large effects, respectively. Clinical relevance was assessed by comparing changes from baseline with previously reported minimal clinically important difference (MCID) thresholds for VAS, AOFAS, and MOXFQ scores, when available.

Because this was a retrospective propensity-matched study based on available cases, an a priori sample size calculation was not performed. However, based on the final matched sample of 150 feet per group, the study was estimated to have approximately 80% power to detect a standardized between-sex difference of Cohen’s d ≈ 0.32 or greater at a two-sided α level of 0.05. Therefore, non-significant findings at 1 year were interpreted in conjunction with observed effect sizes and MCID thresholds rather than p-values alone.

All analyses were conducted using R software (R Foundation for Statistical Computing, Vienna, Austria), with statistical significance set at p < 0.05.

Results

A total of 300 feet (150 male and 150 female) were included in the final analysis. Baseline demographic characteristics and preoperative clinical and radiographic parameters are summarized in Table 1. There were no significant differences between male and female groups in age (53.6 ± 17.3 vs. 53.8 ± 14.6 years, p = 0.937) or follow-up duration (16.7 ± 7.8 vs. 17.6 ± 8.8 months, p = 0.322). Male patients were significantly taller and heavier and had a higher body mass index than female patients (all p < 0.001). All matched covariates showed adequate balance after propensity score matching, with absolute SMDs below 0.1 for age, preoperative HVA, and preoperative IMA (Supplementary Table 1).

Table 1.

Baseline demographic, clinical, and radiographic characteristics of the matched cohort

Variable	Male (n = 150)	Female (n = 150)	p-value
Age (years)	53.6 ± 17.3	53.8 ± 14.6	0.937
Height (cm)	171.1 ± 6.3	157.7 ± 5.4	< 0.001
Weight (kg)	72.8 ± 10.0	56.9 ± 7.9	< 0.001
BMI (kg/m²)	24.8 ± 2.7	22.9 ± 3.0	< 0.001
Follow-up (months)	16.7 ± 7.8	17.6 ± 8.8	0.322
Preop. HVA (°)	31.2 ± 8.2	31.1 ± 8.6	0.905
Preop. IMA (°)	14.2 ± 2.7	14.2 ± 3.1	0.904
Preop. Bony foot width, mm	108.3 ± 6.0	97.7 ± 6.0	< 0.001
Preop. VAS	3.2 ± 1.1	3.1 ± 1.0	0.366
Preop. AOFAS	66.6 ± 13.5	69.7 ± 10.7	0.03
Preop. MOXFQ pain	47.5 ± 14.0	45.1 ± 11.9	0.114
Preop. MOXFQ walking	40.0 ± 11.4	37.2 ± 9.4	0.021
Preop. MOXFQ social	45.7 ± 15.9	40.8 ± 14.8	0.006
HTN, n (%)	44 (29.3%)	22 (14.7%)	0.002
DM, n (%)	12 (8.0%)	5 (3.3%)	0.08
Dyslipidemia, n (%)	36 (24.0%)	33 (22.0%)	0.681
RA, n (%)	0 (0.0%)	3 (2.0%)	0.247
Site: Right, n (%)	74 (49.3%)	75 (50.0%)	0.908

Preoperatively, hallux valgus angle (HVA) and intermetatarsal angle (IMA) were comparable between the two groups. Baseline clinical outcomes differed by sex, with male patients showing lower AOFAS scores and higher MOXFQ walking and social subscores than female patients. Preoperative bony foot width was greater in male patients than in female patients (108.3 ± 6.0 vs. 97.7 ± 6.0 mm, p < 0.001).

Postoperative radiographic and clinical outcomes at 3 months are summarized in Table 2. At 3 months postoperatively, radiographic correction was comparable between male and female patients. Mean HVA improved to 1.1 ± 6.8° in males and 1.5 ± 6.4° in females (p = 0.606), and mean IMA improved to 4.3 ± 2.3° and 4.7 ± 2.2°, respectively (p = 0.156), with small between-sex effect sizes. Bony foot width remained significantly greater in male patients than in female patients (97.5 ± 5.5 vs. 88.2 ± 5.0 mm, p < 0.001), reflecting persistent sex-related differences in absolute skeletal dimensions. Clinically, male patients showed better early postoperative scores, including lower VAS scores, higher AOFAS scores, and lower MOXFQ pain and walking subscores than female patients. The corresponding effect sizes for these early clinical differences were small to moderate.

Table 2.

Radiographic and clinical outcomes at 3 months postoperatively according to sex

Outcome	Male 3mo	Female 3mo	p (3mo)	Cohen’s d
HVA (°)	1.1 ± 6.8	1.5 ± 6.4	0.606	0.06
IMA (°)	4.3 ± 2.3	4.7 ± 2.2	0.156	0.18
Bony foot width, mm	97.5 ± 5.5	88.2 ± 5.0	< 0.001	1.77
VAS	0.2 ± 0.4	0.5 ± 0.8	< 0.001	0.47
AOFAS	91.2 ± 2.0	90.3 ± 3.0	0.002	0.35
MOXFQ pain	12.0 ± 6.0	16.0 ± 10.1	< 0.001	0.48
MOXFQ walking	9.4 ± 4.6	11.2 ± 7.1	0.009	0.3
MOXFQ social	10.3 ± 6.8	11.8 ± 8.0	0.092	0.2

Postoperative radiographic and clinical outcomes at 1 year are summarized in Table 3. At 1 year postoperatively, HVA and IMA correction remained well maintained in both groups, with no significant between-sex differences in HVA or IMA. Mean HVA was 2.3 ± 6.6° in males and 1.8 ± 6.2° in females (p = 0.495), and mean IMA was 4.8 ± 2.7° and 4.7 ± 2.4°, respectively (p = 0.878). Although absolute bony foot width continued to be greater in male patients than in female patients (96.8 ± 5.9 vs. 87.4 ± 5.1 mm, p < 0.001), this difference was consistent with baseline sex-related skeletal size differences. In contrast to the early postoperative findings, clinical outcomes at 1 year were comparable between male and female patients. VAS, AOFAS, and all MOXFQ subscores showed no significant between-sex differences, and the between-group effect sizes were small. Temporal changes in VAS, AOFAS, MOXFQ pain, walking, and social subscores are illustrated in Fig. 4 (A–E).

Table 3.

Radiographic and clinical outcomes at 1 year postoperatively according to sex

Outcome	Male 1 year	Female 1 year	p (1 year)	Cohen’s d
HVA (°)	2.3 ± 6.6	1.8 ± 6.2	0.495	0.08
IMA (°)	4.8 ± 2.7	4.7 ± 2.4	0.878	0.04
Bony foot width, mm	96.8 ± 5.9	87.4 ± 5.1	< 0.001	1.72
VAS	0.1 ± 0.4	0.2 ± 0.5	0.193	0.22
AOFAS	93.9 ± 4.1	93.6 ± 4.4	0.532	0.07
MOXFQ pain	11.2 ± 5.6	12.3 ± 6.9	0.129	0.18
MOXFQ walking	7.3 ± 3.6	7.9 ± 4.6	0.221	0.15
MOXFQ social	8.3 ± 4.9	8.9 ± 5.6	0.359	0.11

Fig. 4.

Clinical outcome scores over time according to sex. A VAS pain score, B AOFAS score, C MOXFQ pain, D MOXFQ walking, and E MOXFQ social scores are shown at the preoperative assessment, 3 months postoperatively, and 1 year postoperatively. Both male and female groups demonstrated marked improvement across all clinical domains with similar temporal trends

Changes in radiographic and clinical outcomes from baseline to 3 months and 1 year postoperatively are summarized in Tables 4 and 5, respectively, as mean changes with 95% confidence intervals. Male patients showed greater improvement in several clinical outcome measures from baseline to 3 months postoperatively, and some change scores remained statistically greater at 1 year. However, both groups exceeded the available MCID thresholds, and absolute clinical outcomes at 1 year were comparable between sexes. Thus, these differences likely reflect baseline functional differences and recovery trajectory rather than clinically superior final outcomes in male patients. Although the absolute reduction in bony foot width was greater in male feet, the percentage reduction from baseline was comparable between groups at both 3 months and 1 year postoperatively.

Table 4.

Changes from baseline to 3 months postoperatively in radiographic and clinical outcomes according to sex

Outcome	Male change	Female change	p-value	MCID
HVA (°)	−30.1 (− 31.5 to − 28.7)	−29.6 (− 31.1 to − 28.1)	0.621	—
IMA (°)	−9.9 (− 10.4 to − 9.4)	−9.5 (− 10.0 to − 9.0)	0.257	—
Bony foot width, mm	−10.8 (− 11.5 to − 10.1)	−9.5 (− 10.1 to − 8.9)	0.003	—
Bony foot width, %	−9.9 (− 10.5 to − 9.3)	−9.6 (− 10.2 to − 9.0)	0.417	—
VAS	−3.0 (− 3.2 to − 2.8)	−2.6 (− 2.8 to − 2.4)	0.002	≥ 1.8
AOFAS	24.5 (22.3 to 26.7)	20.6 (18.9 to 22.3)	0.004	≥ 7.9
MOXFQ pain	−35.6 (− 38.0 to − 33.2)	−29.1 (− 31.6 to − 26.6)	< 0.001	12
MOXFQ walking	−30.6 (− 32.6 to − 28.6)	−26.0 (− 27.8 to − 24.2)	< 0.001	16
MOXFQ social	−35.4 (− 38.1 to − 32.7)	−29.1 (− 31.5 to − 26.7)	< 0.001	24

Values are presented as mean change from baseline with 95% confidence intervals. Percentage change in bony foot width was calculated as follows: (3-month postoperative value − preoperative value) / preoperative value × 100. MCID thresholds are shown for clinical outcome measures where available. Negative values indicate decreases from baseline, whereas positive values indicate increases from baseline. CI confidence interval, MCID minimal clinically important difference

Table 5.

Changes from baseline to 1 year postoperatively in radiographic and clinical outcomes according to sex

Outcome	Male change	Female change	p-value	MCID
HVA (°)	−28.9 (− 30.3 to − 27.5)	−29.3 (− 30.7 to − 27.9)	0.700	—
IMA (°)	−9.5 (− 10.0 to − 9.0)	−9.5 (− 10.0 to − 9.0)	0.990	—
Bony foot width, mm	−11.5 (− 12.3 to − 10.7)	−10.3 (− 11.0 to − 9.6)	0.027	—
Bony foot width, %	−10.5 (− 11.2 to − 9.9)	−10.4 (− 11.1 to − 9.8)	0.858	—
VAS	−3.0 (− 3.2 to − 2.8)	−2.8 (− 3.0 to − 2.6)	0.170	≥ 1.8
AOFAS	27.2 (25.2 to 29.2)	23.9 (22.4 to 25.4)	0.007	≥ 7.9
MOXFQ pain	−36.3 (− 38.7 to − 33.9)	−32.8 (− 34.9 to − 30.7)	0.034	12
MOXFQ walking	−32.7 (− 34.6 to − 30.8)	−29.4 (− 31.0 to − 27.8)	0.007	16
MOXFQ social	−37.4 (− 40.0 to − 34.8)	−31.9 (− 34.3 to − 29.5)	0.003	24

Values are presented as mean change from baseline with 95% confidence intervals. Percentage change in bony foot width was calculated as follows: (1-year postoperative value − preoperative value) / preoperative value × 100. MCID thresholds are shown for clinical outcome measures where available. Negative values indicate decreases from baseline, whereas positive values indicate increases from baseline. CI confidence interval, MCID minimal clinically important difference

Postoperative complications are summarized in Table 6, with 95% confidence intervals provided for the overall complication rates by grade. Overall complication profiles were comparable between male and female groups. Grade 1 complications occurred in 4.7% of male feet and 8.7% of female feet (p = 0.165), with transient neurapraxia being the most common event in both groups. Other Grade 1 complications, including delayed wound healing and superficial cellulitis, were rare. Grade 2 complications were observed in 8.0% of male feet and 5.3% of female feet (p = 0.355). The most frequent Grade 2 events included transfer metatarsalgia in male patients and symptomatic delayed union in female patients, although the incidence of individual complications did not differ significantly between groups. Because the number of Grade 2 events was small and bone-quality parameters were not systematically assessed, we could not determine whether these complications were related to omitted additional hallux valgus–related procedures or underlying bone quality. Grade 3 complications occurred in 15.3% of male feet and 10.0% of female feet (p = 0.165). Common Grade 3 complications included prominent bone, hallux varus, and postoperative stiffness. No cases of deep infection requiring surgery or conversion to open surgery were observed in either group. Overall, no significant differences in complication rates or severity were identified between male and female patients.

Table 6.

Postoperative complications stratified by Clavien–Dindo grade according to sex [17–19]

Complication	Male (n = 150)	Female (n = 150)	p-value
Any Grade 1 complication	7 (4.7%; 95% CI, 1.9–9.4)	13 (8.7%; 95% CI, 4.7–14.4)	0.1650
Delayed wound healing	1 (0.7%)	2 (1.3%)	1.0000
Superficial cellulitis	1 (0.7%)	0 (0.0%)	1.0000
Transient neurapraxia	6 (4.0%)	11 (7.3%)	0.2120
FHL tendon injury	0 (0.0%)	0 (0.0%)	1.0000
Any Grade 2 complication	12 (8.0%; 95% CI, 4.2–13.6)	8 (5.3%; 95% CI, 2.3–10.2)	0.3550
Additional intraoperative fixation	0 (0.0%)	1 (0.7%)	1.0000
Symptomatic delayed union	2 (1.3%)	6 (4.0%)	0.2820
Symptomatic displacement	0 (0.0%)	0 (0.0%)	1.0000
Transfer metatarsalgia	6 (4.0%)	2 (1.3%)	0.2820
Conversion to open surgery	0 (0.0%)	0 (0.0%)	1.0000
Symptomatic recurrence	4 (2.7%)	1 (0.7%)	0.3710
Any Grade 3 complication	23 (15.3%; 95% CI, 10.0–22.1)	15 (10.0%; 95% CI, 5.7–16.0)	0.1650
Screw failure/fracture/cutout/prominence	2 (1.3%)	1 (0.7%)	1.0000
Scar revision	1 (0.7%)	1 (0.7%)	1.0000
Prominent bone	12 (8.0%)	6 (4.0%)	0.1450
Deep infection requiring surgery	0 (0.0%)	0 (0.0%)	1.0000
Hallux varus	5 (3.3%)	5 (3.3%)	1.0000
1st MTP osteoarthritis	1 (0.7%)	1 (0.7%)	1.0000
Stiffness	5 (3.3%)	4 (2.7%)	1.0000

Values are presented as number (%). The 95% confidence intervals for overall complication rates by grade were calculated using the exact binomial method. CI confidence interval, FHL flexor hallucis longus, MTP metatarsophalangeal

Discussion

The most important finding of the present study is that sex-related differences after MITA were most evident during the early postoperative recovery phase, whereas clinical and radiographic outcomes at 1 year were comparable between male and female patients. Male patients presented with worse baseline clinical function despite similar preoperative radiographic deformity, but showed greater early postoperative improvement at 3 months. However, these early differences did not persist at 1 year, suggesting that sex may influence the early recovery trajectory after MITA, whereas absolute clinical and radiographic outcomes at 1 year appear comparable between sexes.

Hallux valgus is more prevalent in women, and most surgical outcome studies have been based predominantly on female cohorts, limiting the understanding of sex-related differences in presentation and recovery [3, 20]. In the present propensity-matched cohort, preoperative HVA and IMA were comparable between sexes, but male patients showed worse baseline clinical function, including lower AOFAS scores and higher MOXFQ walking and social subscores. Because the AOFAS score and MOXFQ are established clinical outcome measures in hallux valgus surgery, this finding may reflect clinically relevant functional impairment rather than radiographic severity alone [21, 22]. However, because factors such as symptom perception, activity-related burden, footwear habits, and treatment-seeking behavior were not directly assessed in this study, these should be regarded only as possible explanations rather than definitive mechanisms. The clinically relevant point is that male patients may present with greater functional impairment even when radiographic deformity is similar to that of female patients.

Male patients demonstrated greater improvement in several clinical outcomes during the early postoperative period. This should be interpreted as a difference in recovery trajectory rather than evidence of superior long-term results in male patients. By 1 year postoperatively, VAS, AOFAS, and MOXFQ scores were comparable between sexes, and the corresponding between-group effect sizes were small. Moreover, improvements from baseline exceeded the available MCID thresholds for VAS, AOFAS, and MOXFQ domains in both groups, supporting the clinical relevance of postoperative recovery regardless of sex [23–25]. These findings are consistent with previous sex-comparative studies showing broadly comparable postoperative outcomes between male and female patients after hallux valgus surgery [4, 5]. The present study extends previous evidence by demonstrating that, in a propensity score–matched MITA cohort with comparable baseline radiographic severity, sex-related differences were reflected mainly in baseline functional status and early recovery trajectory rather than in 1-year clinical or radiographic outcomes.

Radiographic correction was also maintained similarly in both groups. HVA and IMA improved substantially after surgery and showed no significant sex-related differences at either 3 months or 1 year. This is consistent with previous large-cohort MITA data showing reliable radiographic correction through 1 year [10]. Male patients had greater absolute bony foot width at all time points, consistent with known sex-related differences in skeletal morphology [26]. However, the degree of postoperative reduction in bony foot width was comparable between sexes, indicating that the transverse-plane corrective effect of MITA was consistent despite differences in baseline skeletal dimensions. Therefore, larger bony foot width in male patients should not be considered a limiting factor for successful correction with MITA.

Complication profiles were also comparable between male and female patients. Overall complication rates were low, and no significant sex-related differences were observed in complication severity or in the incidence of individual complications. This finding is in line with previous large-cohort MITA data reporting a generally favorable complication profile [10], and suggests that the observed early differences in clinical recovery were unlikely to be explained by differences in postoperative adverse events.

The present findings have practical implications for patient counseling. Surgeons should recognize that male patients may present with greater baseline functional impairment despite comparable radiographic deformity, whereas female patients may show a relatively more gradual early recovery. Nevertheless, both male and female patients can expect comparable clinical and radiographic outcomes by 1 year after MITA. This counseling point may be particularly relevant because previous matched-cohort evidence suggested potential sex-related differences in expectation fulfillment despite similar objective outcomes [5]. Therefore, sex should not be considered a limiting factor for achieving favorable short-term outcomes after MITA, but sex-related differences in baseline function and early recovery may be useful when setting postoperative expectations.

This study has several limitations. First, its retrospective design introduces the potential for selection bias, although propensity score matching was used to reduce baseline imbalances between male and female feet. Second, outcomes were analyzed on a per-foot basis, and bilateral cases were included when both feet met the eligibility criteria. Although radiographic outcomes and pain-related scores were assessed for each operated foot, within-patient correlation and bilateral symptoms may have influenced patient-reported functional domains, particularly the MOXFQ walking and social interaction subscores. Third, follow-up was limited to 1 year, precluding evaluation of longer-term outcomes such as recurrence, progressive degenerative changes, or late hardware-related symptoms. Fourth, inflammatory arthritis was not used as a predefined exclusion criterion, and a small number of patients with rheumatoid arthritis were included when MITA was performed for symptomatic hallux valgus. Finally, some cases required additional concomitant forefoot procedures, such as Weil osteotomy for metatarsalgia or claw toe correction, which were not analyzed separately and may have influenced clinical outcome measures. These limitations should be considered when interpreting the study findings.

Conclusions

Male patients undergoing MITA for hallux valgus presented with worse baseline functional impairment than female patients despite comparable radiographic deformity, but achieved clinically meaningful improvement and clinical and radiographic outcomes comparable to those of female patients at 1 year postoperatively. These findings suggest that sex may influence baseline functional status and the early postoperative recovery trajectory, but should not be considered a limiting factor for favorable 1-year outcomes after MITA. For surgeons, sex-related differences may be useful when counseling patients regarding preoperative symptom burden and early recovery expectations, while both male and female patients can be advised that comparable short-term outcomes are achievable after MITA.

Abbreviations

MITA

minimally invasive distal transverse metatarsal osteotomy–Akin osteotomy

HVA

hallux valgus angle

IMA

intermetatarsal angle

VAS

visual analog scale

AOFAS

American Orthopaedic Foot & Ankle Society

MOXFQ

Manchester–Oxford Foot Questionnaire

Authors’ contributions

S.G.S. proposed the research topic, designed the study protocol, performed surgical procedures for patients included in this study, and supervised the overall conduct of the study as the corresponding author. T.B.K. was responsible for data organization and analysis, conducted the statistical analyses, reviewed the relevant literature, and drafted the manuscript, including preparation of all figures and tables. J.H.L. collected the clinical and radiographic data, performed radiographic measurements and clinical score extraction through medical record review, conducted the anonymization process, and provided the de-identified dataset to the study investigator; he also contributed to study design and IRB-related procedures. D.O.L. also performed surgical procedures for patients included in this study and contributed to clinical interpretation, appraisal, and discussion of the study findings. K.J.C. provided general clinical input and participated in manuscript discussions. All authors reviewed and approved the final manuscript.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The datasets generated and analyzed during this study are not publicly available due to institutional policy and privacy considerations, but are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This retrospective study was reviewed by the Public Institutional Bioethics Committee designated by the Ministry of Health and Welfare, Republic of Korea, and confirmed to be exempt from ethics review by the Korea National Institute for Bioethics Policy (KoNIBP) (Exemption No. P01-202602-01-046). Because this study was based on anonymized data, informed consent to participate was deemed unnecessary by the committee. The study was conducted in accordance with the Declaration of Helsinki and relevant guidelines and regulations.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.