Dynamic Plantar Pressure Analysis and Midterm Outcomes in Percutaneous Correction for Mild Hallux Valgus

Transcription

1 Dynamic Plantar Pressure Analysis and Midterm Outcomes in Percutaneous Correction for Mild Hallux Valgus Alfonso Martínez-Nova, 1 Raquel Sánchez-Rodríguez, 1 Alejo Leal-Muro, 2 Juan Diego Pedrera-Zamorano 1 1 Departamento de Enfermería, Centro Universitario de Plasencia, Avenida Virgen del Puerto 2, Plasencia, Spain, 2 Clínica ALEJO-LEAL, Avenida Ruta de la Plata 13, Cáceres, Spain Received 5 February 2011; accepted 19 April 2011 Published online 5 May 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI /jor ABSTRACT: Mild hallux valgus (HV), which can lead to alteration of the plantar pressure pattern with an overpressure under the hallux, can be repaired percutaneously. Our goals were to determine whether the percutaneous distal soft tissue release (DSTR)-Akin procedure restores the loading pattern and to evaluate which are the determinants of the measures of post-operative outcome. Seventynine percutaneous DSTR-Akin procedures were performed in the same number of patients. The plantar pressure patterns were evaluated using the BioFoot/IBV 1 in-shoe system and compared with measurements from 98 controls. The clinical and radiological outcome parameters measured were the pre- and post-operative AOFAS scores, and the first intermetatarsal, hallux abductus, and first metatarsal hallux declination angles (FIMA, HAA, FMHDA) in weight-bearing radiographs. The mean follow-up was 28.1 (range 24 33) months. The plantar pressure analysis showed a significant decrease ( kpa, p ¼ 0.001) in the mean pressure under the hallux. Significant improvements occurred in the AOFAS scores, and angular deviations were reduced. The post-operative HAA correlated with the mean pressure under the 1st toe (r 2 ¼ 0.132, p < 0.001). The DSTR-Akin percutaneous technique in mild HV restores physiological patterns of pressure on the hallux and achieves significant correction of radiographic angles and commensurate improvement in clinical status. ß 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: , 2011 Keywords: hallux valgus; plantar pressures; Biofoot/IBV 1 ; percutaneous surgery Hallux valgus (HV) is a common disorder of the first ray that causes clinically significant alterations in the distribution of plantar pressures. 1 Radiographically, the normal value of the hallux abductus angle (HAA) is up to 158, while should be considered a mild deformity, a moderate deformity, and >408 a severe deformity. 2 In mild HV, increased pressure occurs under the hallux, 3 while moderate or severe cases show increased pressures under the central or lateral metatarsal heads (MTHs). 4 In recent years, various percutaneous or minimal incision surgical techniques have emerged for the treatment of HV, with the potential advantages that they can be performed without directly exposing the surgical planes. 5 However, little specific literature exists on percutaneous techniques for mild HV that also evaluate the medium- to long-term functional outcome. The combination of a distal soft-tissue release (DSTR) procedure and Akin osteotomy of the proximal phalanx corrects the main pathological deformities in mild HV and can be performed percutaneously. 6 We hypothesized that the correction obtained by the percutaneous DSTR- Akin procedure for mild HV restores the pathological overpressures on the hallux to physiological values. Our aims were: to elucidate whether a difference existed in the forefoot dynamic plantar pressure distribution after surgery (when compared with an agematched healthy control group); and to establish which clinical, radiological, and anthropometric factors determine the post-operative plantar pressures values. Correspondence to: Alfonso Martínez-Nova (T: þ (Ext ); F: þ ; podoalf@unex.es) ß 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. MATERIALS AND METHODS Subjects Inclusion criteria were: pain over the medial eminence while shod; mild HV (158 < HAA 308); FIMA 138; no evidence of osteoarthritis; metatarsus adductus measurements < 148; all data and pre- and post-operative radiographs available; and patient available for a minimum follow-up of 24 months. A total of 79 female patients, with unilateral bunion, met these criteria (79 cases: 43 right and 36 left feet). Control Group A control group was chosen to compare the post-operative plantar pressures with non-pathological feet. It consisted of 98 healthy age-matched women, who were screened by interview and physical examination to rule out obvious foot or gait abnormalities during the 12 months previous to the study. To avoid unnecessary ionizing radiation exposure, only plantar pressure measurements were made. The study was approved by the Human Research Committee of the University (Id:102), and written consent was obtained from all participants after verbal and written explanation of the project. Table 1 summarizes demographic and anthropometric data of patients and control group. Clinical and X-Ray Examination First ray function was assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) hallux metatarsophalangeal interphalangeal clinical rating scale. 7 Standardized weightbearing AP and lateral X-rays were taken, and FIMA, HAA in the frontal plane, and first metatarsal hallux declination angle (FMHDA) in the sagittal plane were made using AutoCAD (Autodesk, Inc., San Rafael, CA) software. 8 Plantar Pressure Equipment and Procedure Plantar pressure measurements were made with the Biofoot/ IBV 1 (IBV, Valencia, Spain) in-shoe system, which has a reliability of 7% between sessions 9 and a sensor measurement accuracy of 2% in the full-scale error. 10 This system 1700

2 DYNAMIC PLANTAR PRESSURE ANALYSIS 1701 Table 1. Mean (SD) Values of Age, Weight, and Body Mass Index for Patients and Controls Age (year) Weight (kg) BMI (kg/m 2 ) Patients (n ¼ 79) Controls (n ¼ 98) BMI, body mass index. consists of a pair of thin (0.7 mm), flexible, polyester insoles each with 64 piezoelectric sensors of 0.5 mm thickness and 5 mm diameter (Fig. 1A). To avoid differences in footwear, all subjects used the same type of shoes during data collection (Fig. 1B). The insoles were calibrated weekly during the study according to manufacturer s instructions. Data were logged in a single 20 s trial at a rate of 100 Hz the optimal for walking measurements 11 when the subjects were halfway along a long (40 m) corridor and had reached a preselected cadence ( steps/min), which is known to show low variability of plantar pressure values. 12 A total of steps were logged, sufficient to provide a high coefficient of reliability. 13 For quality control, a check was made of each pre- and post-measurement by superposing pressure plots of all sensors to allow errors to be detected. If the plots were correct (Fig. 2), the trial was accepted. Surgical Technique All operations were performed from January 2006 to June 2007 by the same surgeon (3rd author) with patients under ankle block anesthesia and without hemostasis. The procedures were monitored via a surgical fluoroscope. A Beaver 64 MIS blade was used to approach the 1st MTPJ through a 3-mm incision in the plantar-medial side of the metatarsal head (MTH), and the joint capsule was dissected using a Freer elevator. The medial eminence was removed using a 4.1 rotatory wedge burr by means of proximal-to-distal movements (Fig. 3A). Through a second incision at the distal first metatarsal space, the adductor hallucis tendon was identified and released from the lateral sesamoid and the base of the proximal phalanx (Fig. 3B). The Akin procedure was performed through a third incision on the medial aspect of the base of the proximal phalanx of the hallux. Using a long Isham-Shannon burr, an osteotomy was Figure 1. (A) Insole with 64 piezoelectric sensors. (B) Insole in place in the medical shoe. performed from the dorsal to plantar cortex, parallel to the base of the phalanx (Fig. 3C). Under fluoroscopic observation, the lateral cortex at the base was left intact. The results of the osteotomy and the metatarsophalangeal alignment were confirmed (Fig. 3D). To repair the capsule, the incision beneath the 1st MTPJ was closed (both skin and capsule; 000 polyglycolic acid). The other incisions were closed with 0000 silk sutures. An abductor and stabilizer bandage was applied to compress the Akin osteotomy. Walking was permitted with a post-operative shoe. Bandages were renewed every 4 days until 4 weeks post-surgery. The first follow-up (until surgical discharge) showed complications (infections, 7 cases; hematomas, 11 cases; and anesthesia of the dorsal cutaneous nerve, 3 cases) that were resolved by physical treatment and medication. The final clinical, plantar pressure, and radiographic examinations were done at a minimum follow-up of 2 years (mean 28.1 months; range months) with no loss at follow-up. The final follow-up complications were two cases of transfer metatarsalgia at the 2nd MTH, and one case at the 3rd MTH. There were no failed procedures, hallux varus, dorsiflexion of the hallux or new bone formation in the medial soft tissues (Fig. 4). Data Collection and Statistical Analysis To analyze the pressure distribution, the software divided the forefoot into seven areas corresponding to the 1st to 5th MTH, the hallux, and the lesser toes. Whole foot contact time (CT), cadence, and mean pressures (MP) in kpa were calculated for each subject. A paired Student s t-test was used to compare the clinical, radiological, and plantar pressure parameters between pre- and post-operative conditions. An unpaired Student s t-test was used to compare outcomes between post-operative and control groups. Significant changes in the parameters of the AOFAS clinical scale were determined using frequency tables and a chi-squared (x 2 ) test. Relationships between plantar pressures and the clinical outcome and radiological measurements were examined using Pearson s correlation coefficient. The determinants of the post-operative parameter values were analyzed by multiple regression ( stepwise backward method). The HAA, FIMA, FMHDA, CT, weight, body mass index, cadence, and age were used as independent variables in a multiple regression analysis to predict the mean pressures (dependent variables). All analyses were performed using SPSS software v (SPSS, Chicago, IL). The significance level was taken to be p RESULTS Plantar Pressure Measurements In the HV group, the cadence was steps/ min pre-operatively and steps/min postoperatively, and the whole foot CT was s pre-operatively and s post-operatively. These differences were not significant (p ¼ and p ¼ 0.283, respectively). Pre-operatively, the 2nd MTH presented the highest pressure (421 kpa), followed by the 3rd and 1st MTHs. The mean pressure beneath the hallux was 328 kpa the 4th-ranked value of the 7 measured. Post-operatively, the greatest pressures continued to be on the 2nd, 3rd, and 1st MTHs (Table 2), while the hallux pressure dropped in rank to the 6th of the 7 analyzed with a value of 152 kpa. The

3 1702 MARTÍNEZ-NOVA ET AL. Figure 2. Verification that the trial was correctly logged: superposition of the pressure plots of all the sensors. paired-sample t-tests showed significant differences in the mean pressures for the hallux, the 4th and 5th MTHs, and the lesser toes (Table 2). In the control group, the greatest mean pressures (MP) were under the 2nd MTH ( kpa), followed by the 3rd and 1st MTHs. The hallux pressure was kpa (Table 2). The cadence and CT were steps/min and s, respectively. No significant differences were found in these parameters compared with the HV group (p > 0.05). The post-operative plantar pressures showed significantly lower 4th and 5th MTH pressures in the controls than the post-operative values. No significant differences occurred in the hallux pressures. Radiological and Clinical Outcomes Pre-operatively, the patients had a FIMA of and an HAA of (Table 3). Their post-operative values were significantly lower (p < 0.001): FIMA of and HAA of No significant changes were found on the FMHDA (Table 3). The pre-operative mean of the AOFAS scale Figure 3. Surgical technique. (A) Exostectomy of the medial eminence; (B) adductor hallucis release; (C) Akin osteotomy, lateral cortex remains intact; (D) fluoroscopic confirmation of the correct osteotomy and MTP alignment. Figure 4. Pre and post-operative radiograph. No new bone formation in the medial soft tissues was observed.

4 DYNAMIC PLANTAR PRESSURE ANALYSIS 1703 Table 2. Plantar Pressures (kpa) in Mild Hallux Valgus: Comparison of Pre- and Post-Operative Values, and the Post-Operative Values with Controls Mean SD (n ¼ 79) Mean SD (n ¼ 98) Zone Pre-Operative Post-Operative p Controls p 1st MTH nd MTH rd MTH th MTH th MTH Hallux Lesser toes SD, standard deviation; MTH, metatarsal head; pre post, paired t-test; post controls, independent t-test. was points. It had increased significantly (p < 0.001) to points by the end of the follow-up period (Table 3). Of the 79 feet, 66 were completely free of pain at the end of follow-up (Fig. 5), and the other 13 were reported with mild or occasional pain around the 1st MTH in recreational activities. Pre-operatively, 52 feet presented painful calluses beneath the hallux, which disappeared in 45 patients post-operatively. The differences were significant (p < 0.001) in all elements of the AOFAS scale (Table 4). Correlations Pre-operatively, the AOFAS scale was negatively correlated with the FIMA and the HAA and with the mean pressure under the hallux (r ¼ 0.222, p ¼ 0.026). The HAA was positively correlated with the mean pressure under the hallux (r ¼ 0.490, p < 0.001) and with the FIMA (Table 5). Postoperatively, the AOFAS scale was correlated negatively with the HAA and with the mean pressure under the hallux (r ¼ 0.503, p < 0.001), and positively with the mean pressure under the 4th and 5th MTHs (Table 5). The only correlation between the pressures and angles was a positive correlation (r ¼ 0.363, p < 0.001) between the HAA and the mean pressure under the hallux (Table 5). No significant correlations were found between FMHDA and any clinical or plantar pressure variable. Plantar Pressure Determinants Post-operatively, weight and cadence together accounted for 11.4% of the variance in a model of mean pressure under the 1st MTH (r 2 ¼ 0.114, p < 0.001, Table 6). Weight was weakly associated with the mean pressure under the 3rd, 4th, and 5th MTHs, and the lesser toes. There was also a weak relationship (8.2%) between contact time and mean 2nd MTH pressure. The HAA showed a relationship Table 3. Radiological and Clinical Pre- and Post-Operative Comparison Mean SD, Pre-Operative (n ¼ 79) Mean SD, Post-Operative (n ¼ 79) p FIMA HAA <0.001 FMHDA AOFAS score <0.001 FIMA, first intermetatarsal angle; HAA, hallux abductus angle; FMHDA, first metatarsal hallux declination angle. Paired t-test. Figure 5. (A) Pre-operative mild HV; (B) clinical aspect after 27 months, with forefoot tightening and correct MTP alignment.

5 1704 MARTÍNEZ-NOVA ET AL. Table 4. Variable The AOFAS Scores Pre-Operative (n ¼ 79) Post-Operative (n ¼ 79) p Table 5. Post-Operative Correlations between AOFAS Score, Radiological Parameters, and Mean Pressures Pre-Operative Post-Operative Pain None Mild Moderate 18 0 Activity No limit <0.001 Daily Recreational 9 0 Shoes Any shoe <0.001 Comfort Modified 4 0 Total 1st MTPJ > < < Hallux IPJ motion No restriction <0.001 Restriction 11 4 Hallux MTPJ þ IPJ stability Stable <0.001 Unstable Callus (MTPJ, IPJ) No < st MTPJ 11 2 IPJ 52 7 Hallux alignment Good <0.001 Fair MTPJ, metatarsophalangeal joint; IPJ, interphalangeal joint. x 2 test. with the mean 1st toe pressure (r 2 ¼ 0.132, p < 0.001). Age was not associated with mean pressures in any of the seven zones. DISCUSSION Pre- and post-operative studies of the treatment and correction of first ray deformity have usually been based on subjective assessments such as clinical function together with the objective measurements of radiographic variables. The developments of in-shoe pressure measurements have made it possible to objectively evaluate the outcome of the procedures on the basis of the pre- and post-operative dynamic plantar pressures. 14 In our case series, the women with mild HV had significantly greater pressures under the hallux than the controls. The negative correlation with the AOFAS score indicates that this increased pressure is pathological. In the pathomechanics of HV, the hallux is deviated laterally. The positive correlation found between the HAA and the pressure under the hallux shows that HAA deviation causes incorrect lift-off with a concomitant increase in pressure. The post-operative Variables r p r p AOFAS 1st IMA NS HAA < AOFAS MP 4th MTH NS MP 5th MTH NS MP hallux < st IMA HAA < <0.001 HAA MP hallux < <0.001 IMA, intermetatarsal angle; HAA, hallux abductus angle; MP, mean pressure; MTH, metatarsal head; NS, not significant. decrease in pressure beneath the hallux is due to the Akin osteotomy (see below), which normalizes the position of the hallux, aligning it relative to the 1st metatarsal, thus allowing normal lift-off from the zone of the tip of the toe and reducing plantar pressure under the hallux. 6 Also, improved muscle-tendon balance distends the soft tissues and allows better positioning of the 1st ray, which could help to preserve the cartilage of the first MTP joint. 15 Comparing the post-operative values with the control group, one observes that the pattern of pressures under the hallux was restored. The percutaneous DSTR-Akin technique achieves a plantar pressure result similar to those of the McBride, 16 Chevron, 1 Lindgren, 17 or Austin 18 open techniques. Since the most important determinant of post-operative pressure values was found to be the HAA (which explained 13.2% of the variance in mean pressure), the reduction of pressure under the hallux seems to be related to the Akin osteotomy. This would be consistent with Deenik et al., 19 who concluded that HAA is the best predictor of surgical correction of HV. Other factors that could explain the other 87.8% of the variance would be foot posture, length of the 1st metatarsal and hallux, relative metatarsal protrusion, and kinetic variables such as stride length. 20 In our study, we would describe the reduction in pressure under the hallux as an improvement given the post-operative correlation between the AOFAS scale and the hallux pressure (patients with less pressure scored higher on the clinical scale). Indeed, the painful callus at the interphalangeal joint of the hallux disappeared in 45 of the 52 feet in which it had been present. The percutaneous surgery also induced changes in the 4th and 5th MTH plantar pressures. These were moderately higher following the intervention, and significantly higher than in the control group. Although

6 DYNAMIC PLANTAR PRESSURE ANALYSIS 1705 Table 6. Post-Operative Multivariate Regression Analyses for Mean Forefoot Pressures (n ¼ 79) Dependent Variable Independent Variable b Coefficient r r 2 p Mean pressure 1st MTH Weight Post-cadence nd MTH Post-CT rd MTH Weight th MTH Weight th MTH Weight Hallux Post-HAA <0.001 Lesser toes Weight MTH, metatarsal head; CT, contact time; HAA, hallux abductus angle. All of the variables were entered into the model using a stepwise backward elimination method. increased plantar pressures under the 2nd and/or 3rd MTHs have been associated with HV surgery, 21 it is infrequent to find increased pressure under the 4th and/or 5th MTHs. Bryant et al., 18 in a control group, found decreased pressure under the 4th and 5th MTHs after 24 months, without any procedure having been performed. Although some differences in walking speeds between the two studies might bias the comparison, the indication seems to be that plantar pressures under the lateral forefoot (4th and 5th MTHs) vary greatly. Although the increase in pressures under the 4th and 5th MTHs observed in our study was associated with higher AOFAS scores, there does not seem to be any clear explanation for this change, which therefore requires further observation and clinical monitoring. The AOFAS scores improved significantly postoperatively from 68.5 to 86.6 points. According to Cancilleri et al., 1 AOFAS values >85 points are considered very satisfactory. Our results for the post-operative AOFAS values parallel those achieved with the open McBride 16 and Chevron 17 techniques, and with other percutaneous techniques such as distal 22 and Reverdin-Isham 23 percutaneous osteotomies. The DSTR- Akin percutaneous technique achieves an appropriate correction of the deformity, which is radiographically similar to its open surgery counterpart. 24 Although this procedure does not correct the redundancy of the medial capsule not allowing correction of the deformity via medial capsulorrhaphy, this was performed by the Akin osteotomy, which restores the alignment of the digit in the transverse plane. Furthermore, this redundancy was not a problem on the medial side of the bunion during the postoperative follow-up. However, MTH osteotomies are more effective in reducing the FIMA. 5,23 While the Reverdin-Isham percutaneous metatarsal osteotomy achieves a 158 correction of the HAA, 23 the postoperative outcome parallels that attained in our study. Our series of cases involved only mild HV, with a mean FIMA less than that of other studies. Since the primary goal of the DSTR-Akin percutaneous technique is to reduce the misalignment of the hallux, one would indeed expect it to lead to a smaller reduction of the FIMA. Post-operatively, weight was a poor determinant of the pressures under the 3rd, 4th, and 5th MTHs and the lesser toes, and, together with the walking cadence, was only a moderate determinant for the 1st MTH pressure. Indeed, although weight is a powerful predictor of static plantar pressure distributions, 25 it does not have the same effect on the dynamic distribution in which other determinants are involved, such as walking cadence. 12 Age also did not emerge as an independent predictor of the mean post-operative pressure in any of the zones. This agrees with the finding of Milnes et al. 26 that age has no direct influence on the range of motion of the first metatarsophalangeal joint or on the AOFAS score. Although Kadakia et al. 8 reported poor results of a percutaneous distal metatarsal osteotomy, our series showed no non-union, osteonecrosis, or early recurrence, and the three cases of transfer metatarsalgia were resolved by orthotics. Our results show that, using the correct indications, this technique provides good radiographic and plantar pressures outcomes, with improvement in the patient s quality of life. There are limitations in our study. First, the follow-up was at mid-term with a mean of 28.1 months. A longer-term follow up (of 5 years) will be required to increase the reliability of the results and conclusions. Also, all patients were women. Although HV is present in up to 58% of women, 27 and they demand surgery more frequently than men, it would be interesting to determine the results in a population of men. In conclusion, the percutaneous DSTR-Akin technique for mild HV modifies the interaction of the foot with the ground during walking, restoring the physiological pattern of pressures on the first ray, and achieves a significant correction of angular alterations, especially of the HAA. This procedure achieves

7 1706 MARTÍNEZ-NOVA ET AL. improvement of the clinical status as reflected in the reduction of pain around the 1st MTP joint, in the improved alignment, and in the reduced pressure under the 1st toe, which also contributes to the disappearance of the interphalangeal joint calluses. REFERENCES 1. Cancilleri F, Marinozzi A, Martinelli N, et al Comparison of plantar pressure, clinical, and radiographic changes of the forefoot after biplanar austin osteotomy and triplanar Boc osteotomy in patients with mild hallux valgus. Foot Ankle Int 29(8): Garrow AP, Papageorgiou A, Silman AJ, et al The grading of hallux valgus: the Manchester Scale. J Am Podiatr Med Assoc 91(2): Martinez-Nova A, Sanchez-Rodriguez R, Perez-Soriano P, et al Plantar pressures determinants in mild hallux valgus. Gait Posture 32(3): Lipscombe S, Molloy A, Sirikonda S, et al Scarf osteotomy for the correction of hallux valgus: midterm clinical outcome. J Foot Ankle Surg 47(4): Magnan B, Pezze L, Rossi N, et al Percutaneous distal metatarsal osteotomy for correction of hallux valgus. J Bone Joint Surg Am 87(6): Martinez-Nova A, Sanchez-Rodriguez R, Leal-Muro A, et al Percutaneous distal soft tissue release-akin procedure, clinical and podobarometric assessment with the biofoot inshoe system: a preliminary report. Foot Ankle Spec 1(4): Kitaoka HB, Alexander IJ, Adelaar RS, et al Clinical rating systems for the ankle-hindfoot, midfoot, hallux, and lesser toes. Foot Ankle Int 15(7): Kadakia AR, Smerek JP, Myerson MS Radiographic results after percutaneous distal metatarsal osteotomy for correction of hallux valgus deformity. Foot Ankle Int 28(2): Martínez-Nova A, Cuevas-García JC, Sánchez-Rodríguez R, et al Biofoot 1 in-shoe system: normal values and assessment of the reliability and repeatability. Foot 17(4): Martínez-Assucena A, Sánchez-Ruiz MD, Barrés-Carsí M, et al Un nuevo método de evaluación diagnóstica y terapéutica de las patologías del pie basado en las plantillas instrumentadas Biofoot/IBV. Rehabilitación (Madr) 37(5): Orlin MN, McPoil TG Plantar pressure assessment. Phys Ther 80(4): Martinez-Nova A, Pascual Huerta J, Sanchez-Rodriguez R Cadence, age, and weight as determinants of forefoot plantar pressures using the Biofoot in-shoe system. J Am Podiatr Med Assoc 98(4): Kernozek TW, LaMott EE, Dancisak MJ Reliability of an in-shoe pressure measurement system during treadmill walking. Foot Ankle Int 17(4): Zammit GV, Menz HB, Munteanu SE, et al Plantar pressure distribution in older people with osteoarthritis of the first metatarsophalangeal joint (hallux limitus/rigidus). J Orthop Res 26(12): Bock P, Kristen KH, Kroner A, et al Hallux valgus and cartilage degeneration in the first metatarsophalangeal joint. J Bone Joint Surg Br 86(5): Mittal D, Raja S, Geary NPJ The modified McBride procedure: clinical, radiological, and pedobarographic evaluations. J Foot Ankle Surg 45(4): Saro C, Andren B, Fellander-Tsai L, et al Plantar pressure distribution and pain after distal osteotomy for hallux valgus: a prospective study of 22 patients with 12-month follow-up. Foot 17(2): Bryant AR, Tinley P, Cole JH Plantar pressure and radiographic changes to the forefoot after the Austin bunionectomy. J Am Podiatr Med Assoc 95(4): Deenik AR, de Visser E, Louwerens JW, et al Hallux valgus angle as main predictor for correction of hallux valgus. BMC Musculoskelet Disord 9: Canseco K, Rankine L, Long J, et al Motion of the multisegmental foot in hallux valgus. Foot Ankle Int 31(2): Toth K, Huszanyik I, Kellermann P, et al The effect of first ray shortening in the development of metatarsalgia in the second through fourth rays after metatarsal osteotomy. Foot Ankle Int 28(1): Magnan B, Samaila E, Viola G, et al Minimally invasive retrocapital osteotomy of the first metatarsal in hallux valgus deformity. Oper Orthop Traumatol 20(1): Bauer T, Biau D, Lortat-Jacob A, et al Percutaneous hallux valgus correction using the Reverdin-Isham osteotomy. Orthop Traumatol Surg Res 96(4): Basile A, Battaglia A, Campi A Comparison of Chevron-Akin osteotomy and distal soft tissue reconstruction- Akin osteotomy for correction of mild hallux valgus. Foot Ankle Surg 6(3): Gravante G, Russo G, Pomara F, et al Comparison of ground reaction forces between obese and control young adults during quiet standing on a baropodometric platform. Clin Biomech 18(8): Milnes HL, Kilmartin TE, Dunlop G A pilot study to explore if the age that women undergo hallux valgus surgery influences the post-operative range of motion and level of satisfaction. Foot (Edinb) 20(4): Nguyen US, Hillstrom HJ, Li W, et al Factors associated with hallux valgus in a population-based study of older women and men: the MOBILIZE Boston Study. Osteoarthritis Cartilage 18(1):41 46.