Effect of First Tarsometatarsal Joint Derotational Arthrodesis on First Ray Dynamic Stability Compared to Distal Chevron Osteotomy

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1 706153FAIXXX / Foot & Ankle InternationalKlemola et al research-article2017 Article Effect of First Tarsometatarsal Joint Derotational Arthrodesis on First Ray Dynamic Stability Compared to Distal Chevron Osteotomy Foot & Ankle International 2017, Vol. 38(8) The Author(s) 2017 Reprints and permissions: sagepub.com/journalspermissions.nav DOI: journals.sagepub.com/home/fai Tero Klemola, MD 1, Juhana Leppilahti, MD, Prof. of Orthop. 1, Vesa Laine, MSc 1,2, Ilkka Pentikäinen, MD, PhD 1, Risto Ojala, MD, PhD 3, Pasi Ohtonen, MSc 4, and Olli Savola, MD, PhD 5 Abstract Background: Hallux valgus alters gait, compromising first ray stability and function of the windlass mechanism at the late stance. Hallux valgus correction should restore the stability of the first metatarsal. Comparative studies reporting the impact of different hallux valgus correction methods on gait are rare. We report the results of a case-control study between distal chevron osteotomy and first tarsometatarsal joint derotational arthrodesis (FTJDA). Methods: Two previously studied hallux valgus cohorts were matched: distal chevron osteotomy and FTJDA. Seventyseven feet that underwent distal chevron osteotomy (chevron group) and 76 feet that underwent FTJDA (FTJDA group) were available for follow-up, with a mean of 7.9 years (range, years) and 5.1 years (range, years), respectively. Matching criteria were the hallux valgus angle (HVA) and a follow-up time difference of a maximum 24 months. Two matches were made: according to the preoperative HVA and the HVA at late follow-up. Matching provided 30 and 31 pairs, respectively. Relative impulses (%) of the first toe (T1) and metatarsal heads 1 to 5 (MTH1-5), weightbearing radiographs, and American Orthopaedic Foot & Ankle Society (AOFAS) (hallux metatarsophalangeal-interphalangeal [MTP-IP]) scores were studied. Results: The relative impulse of MTH1 was higher in the FTJDA group, whereas a central dynamic loading pattern was seen in the chevron group. This result remained when relative impulses were analyzed according to the postoperative HVA. The mean difference in the HVA at follow-up was 6.2 degrees (95% confidence interval, ; P =.001) in favor of the FTJDA group. Conclusion: The dynamic loading capacity of MTH1 was higher in the FTJDA group in comparison to the chevron group. The follow-up HVA remained better in the FTJDA group. Level of Evidence: Level III, case-control study. Keywords: hallux valgus, gait, first tarsometatarsal joint derotational arthrodesis, chevron Hallux valgus has an impact on gait. 5,23 Even mild hallux valgus alters gait to an apropulsive pattern, overloading the central metatarsals. 4 There have been several studies that reported postoperative plantar loading measurements after hallux valgus surgery, 2,3,16,29 but there are a limited number of studies comparing the dynamic plantar loading patterns of the different operative methods after midterm or long-term follow-up. 4 The first metatarsal head (MTH1) supports 29% of the body weight at the late stance during normal gait. 15 Hallux valgus impairs the windlass mechanism, and functional stability of the first ray is compromised. 4,13,28 When first ray mobility increases, the body weight is transferred to the lesser metatarsals. 11,13,30 Increased mobility of the first metatarsal may predispose to metatarsalgia symptoms in patients with hallux valgus. 4,11,14 A generally accepted idea is that hallux valgus correction should restore the loading properties of the first ray. Distal chevron osteotomy is a widely accepted procedure for hallux valgus correction. 1 It is recommended for mild to moderate hallux valgus (hallux valgus angle [HVA] 1 Division of Orthopaedic and Trauma Surgery, Department of Surgery, Oulu University Hospital, Medical Research Center Oulu, University of Oulu, Finland 2 Department of Physical and Rehabilitation Medicine, Oulu University Hospital, Medical Research Center Oulu, University of Oulu, Finland 3 Department of Radiology, Terveystalo Oulu, Oulu, Finland 4 Division of Operative Care, Oulu University Hospital, Medical Research Center Oulu, University of Oulu, Finland 5 Pohjola Sairaala, Helsinki, Finland Corresponding Author: Tero Klemola, MD, Division of Orthopaedic and Trauma Surgery, Department of Surgery, Oulu University Hospital, Medical Research Center Oulu, University of Oulu, PL 21, OYS, Oulu, Finland tero.klemola@ppshp.fi

2 848 Foot & Ankle International 38(8) <40 degrees), but it has also been used for the correction of severe hallux valgus. 9,25,26 The advantage of distal chevron osteotomy is that it is technically less demanding than comparable correction methods, such as scarf osteotomy. 9 First tarsometatarsal joint derotational arthrodesis (FTJDA) is a novel operative method indicated for flexible hallux valgus, despite the severity of hallux valgus deformities. 18,19 With FTJDA, frontal plane correction of the first metatarsal to eversion, relative to the midline of the body, is performed in addition to axial correction of the intermetatarsal angle between the first and second metatarsals (IMA1-2). 18,19 A major difference of FTJDA in comparison to a classic Lapidus 20,21 procedure is that in FTJDA, the first metatarsophalangeal joint is left intact (video available in the online version of the journal). To our knowledge, no previous study has compared distal chevron osteotomy to FTJDA. We hypothesized that FTJDA would restore the first metatarsal loading properties better than distal chevron osteotomy. Methods Matching of the pairs was performed between 2 previously operated hallux valgus cohorts. Both of these earlier studies were previously approved by the local ethics committee. There were no conflicts of interest in either of those studies or the current study. No external financial support was received. Chevron Group The chevron group consisted of participants in a prospective randomized controlled trial comparing 2 distal chevron osteotomy techniques (no osteotomy fixation vs bioabsorbable rod fixation) and 2 postoperative regimens (soft cast vs elastic bandage). One hundred patients with 100 feet were operated on between 1998 and 2002 at the university hospital. All the feet (100%) in the chevron group were operated on by the same surgeon (I.P.). Inclusion criteria for radiographic analysis were age between 20 and 50 years, presence of painful bunions with an HVA of 50 degrees or less, and IMA1-2 of 21 degrees or less. The exclusion criteria were previous bunion surgery, limitation of range of motion of the first metatarsophalangeal joint, flat foot, rheumatoid disease, and pregnancy. The distal metatarsal head was shifted laterally 3 to 4 mm. Lateral capsular release was not performed. Distal soft-tissue realignment was performed with medial capsular tightening in all the operated feet. Seventy-seven of 100 patients participated at a mean long-term follow-up of 7.9 years (range, years). 25,26 There were no adjunctive procedures in the chevron group. Limitation of passive ankle joint dorsiflexion was not examined or treated in the chevron group, as awareness of ankle equinus in hallux valgus was still limited at the time that this study was conducted. FTJDA Group Between 2003 and 2009, 70 consecutive patients (88 feet) with flexible hallux valgus underwent FTJDA at the same university hospital as the chevron group. The indication for the operative procedure was flexible hallux valgus reducible with the peroneus longus activation test. 18,19 In peroneus longus activation test, the patient was standing, lifted the toes off the floor, and increased floor contact under the first metatarsal head at the same time. In this manner peroneus longus activity was increased and long toe flexor activity was decreased. If hallux valgus was reduced both axially and rotationally with this test, the deformity was considered as a good candidate for FTJDA. 18,19 Contraindications were limitations in the preoperative reduction of hallux valgus deformities, indicating degeneration of the first metatarsophalangeal joint, 10 and no previous Keller resection. First tarsometatarsal joint resection was performed with a laterally opening wedge to correct IMA1-2. The amount of eversion correction applied to the first metatarsal was limited by the second metatarsal base. Due to this, the amount of applied rotation varied according to the individual s anatomy. Osteosynthesis was performed with a single, headless, variable pitch compression screw in all FTJDA cases. The first metatarsophalangeal joint, or surrounding soft tissue, was not touched. Sixty-six consecutive patients with 84 feet were enrolled in a retrospective radiological analysis. Fiftyeight patients with 76 feet were evaluated at a mean later follow-up of 5.1 years (range, years). Gastrocnemius elongation was performed as an adjunctive procedure (57/84 feet, 68%) if limitations of passive ankle joint dorsiflexion after a stretching program were present preoperatively. Other adjunctive procedures included flexor digitorum longus transposition for mallet toes (16/84 feet, 19%) and Weil osteotomy for subluxation of metatarsophalangeal joints (9/84 feet, 11%). 18,19 Matching of Case-Control Pairs Two separate matches (matching I and II) were made. In matching I, the chevron and FTJDA groups (77 and 76 feet, respectively) were matched according to the preoperative HVA and a follow-up time difference of a maximum 24 months (Table 1). The 2-year difference between follow-up times was considered clinically acceptable, considering the duration of the mean follow-up times (7.9 years [range, years] and 5.1 years [range, years], respectively). Matching criteria offered 39 pairs initially, but in the chevron group, 9 patients lacked plantar loading measurements, which resulted in 30 matched pairs included in this study. Matching II was performed to examine the effect of residual hallux valgus on dynamic forefoot loading between the groups. The matching criteria were the postoperative HVA at the latest follow-up and a follow-up time difference

3 Klemola et al 849 Table 1. Demographic Data of Paired Groups According to Preoperative HVA (n = 30). FTJDA Chevron Mean Difference (95% CI) Preoperative HVA, deg 29.3 ± ± ( 0.3 to 0.5) Follow-up time, mo 72.4 ± ± (10.2 to 17.2) Age, y 51.3 ± ± (8.8 to 18.6) Female/male sex, n (% female) 29/1 (96.7) 30/0 (100) Notes: Values are shown as mean ± standard deviation unless otherwise indicated. The secondary criterion for matching was follow-up time (difference of less than or equal to 24 months). Abbreviations: CI, confidence interval; FTJDA, first tarsometatarsal joint derotational arthrodesis; HVA, hallux valgus angle. Table 2. Demographic Data of Paired Groups According to Postoperative HVA (n = 31). FTJDA Chevron Mean Difference (95% CI) Postoperative HVA, deg 16.9 ± ± ( 0.2 to 0.3) Follow-up time, mo 74.1 ± ± (10.2 to 17.2) Age, y 51.2 ± ± (8.8 to 18.6) Female/male sex, n (% female) 31/0 (100) 31/0 (100) Notes: Values are shown as mean ± standard deviation unless otherwise indicated. The secondary criterion for matching was follow-up time (difference of less than or equal to 24 months). Abbreviations: CI, confidence interval; FTJDA, first tarsometatarsal joint derotational arthrodesis; HVA, hallux valgus angle. of a maximum 24 months (Table 2). Thirty-one pairs were matched accordingly. Only relative impulses were analyzed from matching II. Radiological Measurements Both groups underwent radiological measurements. The measurements were supervised by the senior radiologist (R.O.) who did not participate in the clinical examination or the treatment of the patients. The HVA (angle between the longitudinal axes of the first metatarsal and proximal phalanx of the first toe [T1]) and IMA1-2 (angle between the longitudinal axes of the first and second metatarsals) were measured from anteroposterior images according to the guidelines of the American Orthopaedic Foot & Ankle Society (AOFAS) ad hoc committee on angular measurements. 8 The calcaneal pitch angle and Meary angle (angle between the longitudinal axes of the talus and the first metatarsal) were measured from lateral weightbearing radiographs. 7 The tibial sesamoid position was evaluated using the LaPorta classification (1-7). 22,24 Radiological analysis was conducted according to matching I (preoperative HVA and follow-up time difference of a maximum 24 months). Clinical Outcome Measurements Both groups were evaluated with AOFAS (hallux metatarsophalangeal-interphalangeal [MTP-IP]) scores. 17 Due to the retrospective nature of the FTJDA group, the AOFAS (MTP-IP) scores were acquired only at the latest follow-up. Plantar Loading Measurements The participants walked barefoot at their most comfortable speed for about 10 minutes without breaks, and a gait analysis was performed throughout using the Footscan D gait scientific 2m system (RSscan, International NV, Olen, Belgium), avoiding acceleration and deceleration phases during data collection. The patients took a few minutes to familiarize themselves by walking over the plate before the recording was started. During the walk, the pressure and impulse screens were viewed, and the recording was started after walking seemed comfortable. All the measurements and analyses were performed by one examiner (V.L.). The system measured both the time-based gait symmetry characteristics, including velocity, and the loading parameters such as plantar pressures, forces, and impulses (force time integral) using the pressure sensor plate. The measured area was 33 cm 195 cm, and foot loading was measured by conductive polymer sensors with a size of 5 mm 7 mm and sensitivity of 0.27 to 127 N/cm 2. The measurements were made at the recording speed of 125 Hz. The weight calibration measurement was made daily before the measurement sessions using the calibration screen of the program. Every step was checked before analysis, and the automatic zone selection was corrected manually, where needed. The forefoot impulse (force time integral, Ns) distribution was investigated in this study. The relative impulse distribution was calculated so that the distal metatarsals (MTH1-5) and T1 together equaled 100%. The gait analysis results of each foot were the mean of 10 steps. Plantar

4 850 Foot & Ankle International 38(8) Table 3. Relative Loading Distribution of MTH1-5 and T1 According to Preoperative HVA. FTJDA Chevron Mean Difference (95% CI) P Value a MTH ± ± (4.2 to 12.3) <.001 MTH ± ± ( 3.2 to 2.6).839 MTH ± ± ( 6.9 to 1.8).001 MTH ± ± ( 6.0 to 0.5).022 MTH5 9.0 ± ± ( 0.5 to 4.2).124 T1 5.4 ± ± ( 4.5 to 0.1).055 Notes: Values are shown as mean ± standard deviation unless otherwise indicated as a percentage of total loading (100%). Force time integral (impulse) was measured during leveled gait. Pairs (n = 30) were matched according to the preoperative HVA and a follow-up time difference of less than or equal to 24 months. Abbreviations: CI, confidence interval; FTJDA, first tarsometatarsal joint derotational arthrodesis; HVA, hallux valgus angle; MTH1, first metatarsal head; MTH2, second metatarsal head; MTH3, third metatarsal head; MTH4, fourth metatarsal head; MTH5, fifth metatarsal head; T1, first toe. a Significance, reported as 2-tailed P value. loading measurements and analyses were performed blinded, as the examiner (V.L.) did not know the matching results of the groups. Statistical Methods Summary statistics are presented as mean ± standard deviation. Comparisons between matched pairs were performed using a paired-samples t test. Three different subgroups were created according to adjunctive procedures for the FTJDA group, and subgroup analyses were performed: (1) gastrocnemius elongation versus no elongation, (2) mallet toe correction (with or without Weil osteotomy) versus no lesser toe procedure, and (3) either of the previous adjunctive procedures versus no adjunctive procedures. Student s t-test was used for subgroup comparisons. Two-tailed P values are presented, and all analyses were performed using SPSS for Windows (Version 21.0; IBM Corp, Armonk, NY, USA). Results In matching I (preoperative HVA), the FTJDA group had higher relative impulses in MTH1 (8.2%; P <.001), whereas the chevron group had higher relative impulses in MTH3 (4.3%; P =.001) and MTH4 (3.2%; P =.022) (Table 3 and Figure 1). In matching II (postoperative HVA), the FTJDA group had higher relative impulses in MTH1 (10.6%; P <.001) and MTH5 (2.6%; P =.049), whereas the chevron group had higher impulses in MTH3, MTH4, and T1 (4.8% [P =.005], 3.7% [P =.018], and 3.7% [P =.001], respectively) (Table 4 and Figure 2). The operative procedure improved the mean HVA by 6.6 ± 5.6 degrees in the chevron group and by 12.9 ± 7.0 degrees in the FTJDA group in matching I. The mean difference at the latest follow-up was 6.2 degrees (95% confidence interval, ; P =.001) (Table 5). Figure 1. Relative impulse (%) distribution in the forefoot area between the chevron group (shaded) and FTJDA group (white). Pairs were matched according to the preoperative hallux valgus angle and a follow-up time difference of a maximum 24 months. The latest follow-up results for IMA1-2 (P =.964), the Meary angle (P =.750), the calcaneal pitch angle (P =.467), and the LaPorta classification (P =.662) did not differ significantly between the groups. However, the difference in the change of the achieved correction (preoperative vs latest follow-up) between the groups for the calcaneal pitch angle (P <.001) and Meary angle (P <.001) was statistically significant. The mean AOFAS (MTP-IP) scores were 81 ± 7 in the chevron group and 86 ± 16 in the FTJDA group at the latest follow-up (P =.128). According to subgroup analyses in the FTJDA group, feet with lesser toe procedures had a significantly lower relative impulse in MTH2 in both matching I and II (22.6% ± 6.5% vs 28.3% ± 5.3%, respectively [P =.025], and 21.7% ± 6.4% vs

5 Klemola et al 851 Table 4. Relative Loading Distribution of MTH1-5 and T1 According to Postoperative HVA. FTJDA Chevron Mean Difference (95% CI) P Value a MTH ± ± (6.0 to 15.2) <.001 MTH ± ± ( 3.8 to 1.6).427 MTH ± ± ( 8.0 to 1.5).005 MTH ± ± ( 6.7 to 0.7).018 MTH5 9.4 ± ± (0.0 to 5.1).049 T1 5.2 ± ± ( 5.7 to 1.6).001 Notes: Values are shown as mean ± standard deviation unless otherwise indicated as a percentage of total loading (100%). Relative impulse (relative force time integral, %) was measured during the contact phase of gait. Pairs (n = 31) were matched according to the postoperative HVA (late followup) and a follow-up time difference of less than or equal to 24 months. Abbreviations: CI, confidence interval; FTJDA, first tarsometatarsal joint derotational arthrodesis; HVA, hallux valgus angle; MTH1, first metatarsal head; MTH2, second metatarsal head; MTH3, third metatarsal head; MTH4, fourth metatarsal head; MTH5, fifth metatarsal head; T1, first toe. a Significance, reported as 2-tailed P value. Figure 2. Relative impulse (%) distribution in the forefoot area between the chevron group (shaded) and FTJDA group (white). Pairs were matched according to the postoperative hallux valgus angle (late follow-up) and a follow-up time difference of a maximum 24 months. 28.3% ± 5.5%, respectively [P =.009]). Furthermore, feet with either of the adjunctive procedures had a higher relative impulse in MTH5 in matching I (11.4% ± 6.2% vs 5.8% ± 3.2%, respectively; P =.012). In the FTJDA group, the relative impulse distribution did not differ significantly between gastrocnemius elongation versus no elongation (data not shown). Discussion In the FTJDA group, the dynamic forefoot loading distribution (relative impulse, %) showed a higher loading capacity of MTH1 during the contact phase of gait compared to the chevron group (Figure 1). This result was preserved when the effect of the late postoperative HVA (matching II) on the dynamic forefoot loading distribution was examined between the groups. In matching II, there was a higher relative impulse of MTH5 in the FTJDA group (P =.049). However, the relative impulse value diminished gradually from the second metatarsal to lateral metatarsals in the FTJDA group. For this reason, the higher relative impulse in MTH5 was not considered as an indicator for the lateral loading pattern but as a result of more evenly distributed forefoot loading compared to the chevron group. The results of matching II suggest that if recurrence of hallux valgus develops, FTJDA is still capable of maintaining better first ray dynamic stability compared to distal chevron osteotomy (Figure 2). The relative impulse (relative force time integral, %) distribution of the forefoot region (T1, MTH1-5) was chosen as the gait parameter in this study, as impulse shows total loading instead of momentary pressures or force peaks. The relative impulse distribution describes the cumulative dynamic properties of the forefoot during gait. The forefoot region was chosen as a special area of interest because hallux valgus has been shown to produce apropulsive loading patterns. 4 Glasoe et al 13 concluded that patients with hallux valgus had significantly more dorsal mobility of the first ray compared to normal controls. Thus, stability of the first ray may be considered as an important goal in hallux valgus surgery. The results of the relative impulse distribution indicate inferior dynamic stability of the first metatarsal (central loading pattern) in the chevron group compared to the FTJDA group (Figure 1). This result is in agreement with the findings of King et al, 16 who reported a central loading pattern after distal chevron osteotomy in comparison to the Lapidus procedure. Cancilleri et al 4 also reported a central loading pattern after distal chevron osteotomy. Brodsky et al 2 reported that proximal crescentic osteotomy produces increased central plantar loading patterns postoperatively, even if the first metatarsal had been plantarly displaced during surgery and the metatarsal length had been preserved.

6 852 Foot & Ankle International 38(8) Table 5. Radiological Results for Groups Matched by Follow-up Time and Preoperative HVA. Preoperative Follow-up Mean Difference (95% CI) P Value HVA, deg FTJDA 29.3 ± ± ( 9.5 to 3.0).001 a Chevron 29.2 ± ± (3.2 to 9.3) <.001 b IMA1-2, deg FTJDA 12.9 ± ± ( 1.6 to 2.0).86 a Chevron 13.0 ± ± ( 1.7 to 1.8) >.90 b Meary angle, deg FTJDA 4.8 ± ± ( 3.6 to 2.6).75 a Chevron 4.0 ± ± ( 9.8 to 4.5) <.001 b Calcaneal pitch angle, deg FTJDA 20.0 ± ± ( 1.5 to 3.3).47 a Chevron 21.4 ± ± ( 3.5 to 1.4) <.001 b LaPorta classification (1-7) FTJDA 5.1 ± ± ( 0.5 to 0.75).66 a Chevron 4.5 ± ± ( 0.1 to 1.2).087 b Note: Values are shown as mean ± standard deviation unless otherwise indicated. Abbreviations: CI, confidence interval; FTJDA, first tarsometatarsal joint derotational arthrodesis; HVA, hallux valgus angle; IMA1-2, intermetatarsal angle between first and second metatarsals. a P value for the mean difference at follow-up. b P value for the mean difference for the change (from preoperative to follow-up results) between the matched pairs. On the other hand, Coughlin and Jones 6 concluded that distal soft-tissue realignment combined with proximal crescentic osteotomy increased the stability of the first ray without the need for FTJDA. According to Faber et al, 12 the Hohmann distal metatarsal osteotomy and Lapidus procedures produced similar long-term results, and the presence or absence of hypermobility in the first tarsometatarsal joint made no difference on the outcomes. The radiological results (change in the Meary angle and calcaneal pitch angle between the groups) and the dynamic loading measurements of the current study do not support the findings of Coughlin and Jones 6 and Faber et al. 12 However, the impact of different osteotomy techniques (distal chevron osteotomy, proximal crescentic osteotomy, and Hohmann procedure) used in these studies should be noted. 6,12,26 In their biomechanical study, Faber et al 11 concluded that the relative contribution of first tarsometatarsal joint mobility to total first ray mobility was greater in the medial than in the dorsal direction in hallux valgus. They also concluded that peroneus longus function has a significant stabilizing effect against dorsal angular displacement. 11 Considering this, the eversion correction of FTJDA may explain the higher relative impulse of MTH1 in comparison to distal chevron osteotomy. 18,19 In their cadaveric study, Perez et al 27 described the stabilizing effect of the eversion locking mechanism to dorsal mobility of the first metatarsal. In FTJDA, the first tarsometatarsal joint eversion locking mechanism fully benefits from first metatarsal eversion correction. 18,19 Considering this, FTJDA may produce better first ray sagittal stability than the modified Lapidus procedure in which stability is based on first tarsometatarsal joint fusion and realignment. The classic version of the modified Lapidus procedure does not address the rotation. When the modified Lapidus procedure is considered, we recommend testing the flexibility of hallux valgus preoperatively with the peroneus longus activation test. 18,19 If hallux valgus turns out to be flexible, we recommend proceeding with FTJDA instead of the modified Lapidus procedure. In FTJDA, there is no need for medial capsular tightening when hallux valgus is flexible, despite medial capsular attenuation. 18,19 In the Lapidus procedure, first ray instability is often used as the determining factor for the procedure. However, estimating clinically relevant first ray instability may be difficult in practice due to, for example, generalized joint laxity. In FTJDA, the flexibility of hallux valgus is the determining factor for the use of the procedure. The concept of flexible hallux valgus also includes possible instability of the first ray. Flexor hallucis longus force resists dorsal angular displacement but also increases medial angular displacement of the first tarsometatarsal joint (metatarsus primus varus), making it a potential factor in the recurrence of hallux valgus. 11 In FTJDA, the adverse foot widening effect is efficiently prevented with the fusion of the first tarsometatarsal joint. In distal chevron osteotomy, postoperative medial angular displacement of the first tarsometatarsal joint is possible due to, for example, flexor hallucis longus overuse. This may compromise the windlass mechanism and the mechanical properties of the first ray and increase the risk

7 Klemola et al 853 of recurrence of hallux valgus. Our results support this theory because in the chevron group, the relative impulse was higher in T1 relative to MTH1 than in the FTJDA group. Flexor hallucis longus overuse could be a compensatory mechanism to insufficient first metatarsal dynamic stability. According to Jacob, 15 in a normal foot, one third of the body weight should be borne by MTH1 during early heel rise. In principle, this demand may also be fulfilled with osteotomy correction. On the other hand, the central dynamic forefoot loading distribution seen in the chevron group may be considered as a risk factor to overload symptoms, such as lesser toe metatarsalgia and painful plantar callosities. 4 With a weightbearing radiograph, sesamoid coverage is partly based on the stability of the first ray. The more stable the first ray is, the better it can resist overall pronation of the foot and thus the better the metatarsal head seems to be placed on the sesamoid relative to the floor. However, medial arch stability is not based only on stability of the first tarsometatarsal joint. If overall pronation of the foot is increased due to any reason (ankle equinus, hindfoot valgus, forefoot varus, etc), the sesamoids seem to be located laterally on an anteroposterior weightbearing view, even if metatarsosesamoid joints could be congruent. This type of lateralization cannot be prevented with local distal soft-tissue procedures but with better overall function of the windlass mechanism, in our opinion. Weightbearing radiographs also suggest better stability of the medial longitudinal arch in the FTJDA group compared to the chevron group. The difference in achieved hallux valgus correction at the latest follow-up was significantly (P <.001) in favor of FTJDA. The differences in the achieved correction (preoperative vs latest follow-up) for the calcaneal pitch angle (P <.001) and Meary angle (P <.001) were also higher in the FTJDA group. Radiological results suggest better mechanical function of the windlass mechanism and improved stability of the first ray during propulsion. The strengths of this study were exact matching of the HVAs (mean difference of both preoperative and postoperative HVA matches was 0.1 degrees), a good number of matched pairs (30 and 31 pairs), and relatively long followup times in both groups (mean of 5.1 years in the FTJDA group and 7.9 years in the chevron group). In both groups, the operative procedures were mostly performed by a single surgeon (88% and 100%, respectively). The gait was analyzed in the same unit by the same examiner, who did not know the matching results of this case-control study. Our subgroup analyses showed that there is some evidence of a different relative impulse distribution between operated feet, with and without adjunctive procedures, in the FTJDA group. However, we lacked statistical power to fully investigate this finding. One limitation of this study is that gait analysis data were collected only at the latest follow-up. Another limitation is the retrospective nature of the FTJDA group. Due to this fact, the preoperative outcome scores were not obtained. The clinical examination protocol also differed between the groups: in the chevron group, ankle equinus was not examined or treated. In the FTJDA group, hallux valgus deformities were flexible, which was not specifically tested in the chevron group. 18,19,25,26 In conclusion, FTJDA produced a better postoperative dynamic loading capacity of the first ray when compared to distal chevron osteotomy. According to weightbearing radiographs, the difference in the follow-up HVA was significantly better in the FTJDA group. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article. Supplemental Material Supplementary video is available online with this article. References 1. Austin DW, Leventen EO. A new osteotomy for hallux valgus: a horizontally directed V displacement osteotomy of the metatarsal head for hallux valgus and primus varus. Clin Orthop Relat Res. 1981;157: Brodsky JW, Beischer AD, Robinson AH, et al. Surgery for hallux valgus with proximal crescentic osteotomy causes variable postoperative pressure patterns. Clin Orthop Relat Res. 2006;443: Bryant AR, Tinley P, Cole JH. 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