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Category: Hindfoot; Ankle Introduction/Purpose: Weight Bearing CT (WBCT) has been proven to be effective in hindfoot alignment assessment. However, we have noted that in both WBCT examination and evaluation, positioning of the foot has not been sufficiently prioritized. We hypothesized that changing the foot orientation will significantly affect the measurement of the hindfoot, which will in turn affect further clinical decision making. Methods: WBCT scans of ten feet without any foot and ankle deformity were loaded in CubeVue software. The foot was aligned to a neutral (0°) position based on the 2nd ray and the heel, and was then rotated 5°, 10°, 15° and 20° both externally and internally to simulate malposition. The 'semi' three dimensional hindfoot Moment Arm (HMA) was evaluated with the foot in these different positions. For measured parameters, varus alignment was recorded as a negative value, and valgus alignment was recorded as a positive value. Each measurement was repeated twice to minimize bias. A linear regression model was used to analyze the relationship of the HMA value and the rotation angles. An intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliability. Statistical analysis was completed using SAS 9.4. Results: When rotating the foot from external 20° to internal 20°, the HMA demonstrated a linear change in hindfoot alignment from varus to valgus. A 1° increase in the rotation angle caused 0.52 (±0.03) mm increase in the HMA value (Figure 1). The HMA measurements had excellent inter- and intra-observer reliability (ICC >= 0.9) (Table 1). Both CT images and measured values confirmed that internal rotation changed a neutral into a valgus hindfoot, and external rotation changed a neutral hindfoot into varus (Figure 2). Conclusion: When using current two or 'semi' three-dimensional methods to evaluate hindfoot alignment on WBCT scans, positioning the foot in the correct orientation is critical. Malrotation and malposition of the foot will cause significant impact on measurements and generate false data as well as misdiagnoses. This study was performed on normal feet but is clinically relevant when applied to deformities, particularly those associated with abduction or adduction of the midfoot and forefoot while current knowledge about deformed foot positioning is limited. This is an important topic for future investigation.

Category: Hindfoot; Other Introduction/Purpose: Radiographic characteristics of Müller-Weiss disease (MWD) include compression and flattening of the lateral one-third of the tarsal navicular, lateral and inferior the shift of the talar head, followed by a varus hindfoot which produces a paradoxical planovarus. The radiographic Stage of the disease has no direct correlation with symptoms and therefore X-ray and CT have limitations in the surgical decision making for treatment. This study aimed to determine the predictive value of the use of SPECT-CT in surgical decision making. We hypothesized that SPECT-CT will highlight the specific joints actively involved in the disease process, and with the correct selective arthrodeses as well as intraoperative correction of malalignment of the hind and midfoot, improved clinical outcomes can be achieved. Methods: This was an IRB approved prospective study with 24 MWD patients (25 feet) enrolled. All patients failed conservative treatment and agreed to undergo SPECT-CT examination for further diagnostic purposes. The SPECT-CT scans were evaluated to identify the joints that were actively involved. Weightbearing X-rays (WBXR) and weightbearing CT scans (WBCT) were performed to assess the pre and postoperative midfoot and hindfoot alignment, including the talo-first metatarsal angle (TFMA), talonavicular coverage angle (TNCA), talocalcaneal angle (TCA), the Tomeno-Méary angle (TMA) and calcaneal pitch angle (CPA), and the hindfoot alignment angle (HAA). The surgical plan was based on the SPECT-CT and included guided arthrodesis, correction of hindfoot varus, talonavicular subluxation, and restoration of the medial arch. The AOFAS midfoot scale, visual analog scale (VAS), Foot and Ankle Ability Measure (FAAM) Sports subscale, and the 36-Item Short Form Health Survey (SF-36) were used pre and postoperatively to evaluate the clinical outcomes. Results: There were 20 females and 4 males with a mean age of 57.2 years and a mean duration of symptoms of 5.24 years. According to the Maceira staging system, there were 2 stage II, 8 stage III, 13 stage IV and 2 stage V. Three feet received isolated talonavicular arthrodesis, a talonavicular-cuneiform arthrodesis (10), triple arthrodesis (9), and triple plus navicular-cuneiform arthrodesis (3). The median follow-up time was 53.5 (range, 20-91) months. There were statistically significant improvements in the midfoot and hindfoot alignments (TNCA, TMA, CPA, HAA) and patient reported outcome measure scores (AOFAS, VAS, SF- 36 PF, SF-36 BP). Six patients required additional surgery (3 for hardware removal, and 3 for nonunion). No patient required revision surgery for arthritic pain in adjacent joints. Conclusion: SPECT-CT guided selective arthrodesis and correction of midfoot and hindfoot alignment can achieve both satisfactory clinical and radiographic outcomes in treating different stages of MWD. SPECT-CT is a very helpful tool to identify actively involved joints with arthritis secondary to the malalignment associated with this disease process, and avoids unnecessary arthrodesis of joints not actively involved in the disease process.

Category: Hindfoot; Ankle Introduction/Purpose: The Hindfoot Moment Arm (HMA) has been used to evaluate the hindfoot alignment with the Saltzman weightbearing XRay images (1), and was recently introduced into the field of weightbearing CT (WBCT) by Saltzman et al (2). The authors of this study have noticed that when using the Saltzman WBCT HMA technique, it is very difficult to determine the specific 'one' image in coronal plane scans with the widest tibial diaphyseal to draw the long axis of the tibia. The purpose of this study was to introduce a modified technique of measuring HMA in WBCT scans and compare the inter and intra-observer reliabilities between the modified and the Saltzman WBCT HMA techniques. Methods: WBCT scans of ten healthy limbs were loaded in CubeVue software. The foot was aligned in the correct orientation in the transverse plane based on the 2nd ray and the heel and the HMA was evaluated using the modified and Saltzman techniques. Using the modified technique, the sagittal plane thickness of one scan cut was increased to include the full width and length of the tibia and the axis of the distal tibia was identified by connecting two circles tangential to both cortices of the tibia. The weightbearing point of the calcaneus was located and the HMA was evaluated by measuring the perpendicular distance of the calcaneus weightbearing point to the axis of the distal tibia with varus a negative and valgus alignment a positive value. Intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliability of the two HMA techniques in SAS 9.4. Results: Both techniques had excellent intra- and interobserver reliability (Saltzman WBCT HMA intra-observer ICC=0.97, Saltzman WBCT HMA inter-observer ICC=0.94, the modified WBCT HMA intra-observer ICC=0.99, the modified WBCT HMA inter-observer ICC=0.91) (Table 1). Conclusion: The modified WBCT HMA was equivalent to the Saltzman technique in both inter and intra-observer reliabilities. The authors found that the modified technique was easier and less time consuming to perform in identifying the axis of the tibia since the modified technique uses multiple cuts to restore the full thickness of tibia, which not only reduces potential error, but also saves time during measurements. Compared with a relatively shorter tibia in one cut, the reconstructed tibia provides a longer and clearer shaft to work with, which allows both proximal and distal circles to be drawn with higher precision (Figure 1). 1. Saltzman, C. L., & El-Khoury, G. Y. (1995). The hindfoot alignment view. Foot & Ankle International, 16(9), 572-576. 2. Arena, C. B., Sripanich, Y., Leake, R., Saltzman, C. L., & Barg, A. (2021). Assessment of hindfoot alignment comparing weightbearing radiography to weightbearing computed tomography. Foot & Ankle International, 42(11), 1482-1490.

Category: Hindfoot; Other Introduction/Purpose: When the hindfoot is in varus the tarsal canal becomes visible on a lateral Xray (XR) and has been referred to as a 'target sign'. However, the sinus tarsi (ST) and tarsal canal (TC) are not easily visible radiographically when associated with a flatfoot. The dimensions of both the ST and TC in normal and flatfeet are unknown, but if understood, could help with the design and implantation of an arthroereisis, a commonly performed procedure for correction of pediatric flatfoot deformity. Knowing the size of the TC will also reduce postoperative complications of arthroereisis such as stiffness, resulting from too large an implant. The aim of this study was to take three-dimensional (3D) measurements of the TC in pediatric flatfeet under weightbearing (WB) conditions. Methods: This was a prospective IRB approved study in pediatric patients with flexible flatfeet and asymptomatic children without flatfeet who were reviewed and analyzed. Using 3D computer-aided design (CAD) models from weightbearing CT (WBCT) scans, the following parameters were measured: the widest diameter of the posteromedial tarsal canal (WDPTC), the narrowest supero- inferior diameter of the tarsal canal (NSDTC), the length of the tarsal sinus, (LTS), the length of the tarsal canal (LTC) and the tarsal sinus and canal volume (TSCV). Correlations between patient age, Meary's angle, foot and ankle offset (FAO), and each of the above measured parameters were investigated. Both weight bearing and non-weight bearing CT scans were used for study to investigate the effect of bearing weight on the above-mentioned parameters. (Figures 1, 2). Results: Twenty-two children with flexible flatfeet (age range 9-14) and fourteen children with no foot deformity (age 9-15) were included for study. With the WBCT the TSCV decreased by 20% in comparison with non-weightbearing evaluation. The TSCV, the widest diameter of the anterolateral tarsal sinus (WDATS) and LTC decreased in flatfeet both under WB and NWB conditions compared with the control group. A positive linear correlation was found between the TSCV and patient age (r = 0.7307, P < 0.0001), while negative linear correlations were found between the TSCV and FAO (r = -0.5188, P < 0.0001) and Meary's angle (r = -0.3132, P = 0.0019). The tarsal sinus and tarsal canal volume significantly decreased in the flatfoot group during weight bearing, while the volume of the tarsal canal remained unchanged. Older age was not associated with either a wider tarsal canal or its orientation. Conclusion: Although the tarsal sinus and canal volume was positively associated with patient age, there was a negative correlation with both the FAO and Meary's angle. These findings may be very relevant in future study of the subtalar joint in both children and adults, and clearly have an implication for treatment of the pediatric flatfoot with arthroereisis.

Category: Hindfoot; Ankle; Midfoot/Forefoot Introduction/Purpose: The foot and ankle offset (FAO) was developed as a 3D biometric tool to measure hindfoot alignment on weightbearing CT (WBCT) scans. It corresponds to the offset between the hindfoot-to-forefoot midline and the talus and is reported as a percentage of foot-length. (1) Recently, with increased availability of WBCT in both research and clinical practice, the FAO has been widely used for hindfoot alignment assessment. (2) However, after extensive review of WBCT scans the authors of this study have noticed that FAO has a high false negative rate. This study aimed to demonstrate why FAO is inadequate in assessing 3D hindfoot alignment using both case examples and mathematical algorithms. Methods: This was a retrospective study including a cohort of 31 cases with various clinical diagnoses selected from a data base of WBCT in 260 patients. The deformities included valgus or varus ankle deformities, hindfoot deformities combined with sagittal plane deformities of the foot and ankle, rocker bottom foot deformity, ankle equinus, metatarsus primus elevatus, and first metatarsal plantarflexion. All of the latter deformities caused one or more parts of the triangular base for FAO evaluation (the 1st metatarsal, the 5th metatarsal and the calcaneus) to remain off the floor. The medical charts and WBCT scans of each patient were reviewed to evaluate the deformities in more detail. The FAO was measured by two fellowship trained foot and ankle surgeons separately. The clinical and radiographic diagnoses were compared with the FAO value to determine the accuracy and utility of the latter measurement. Limitations of FAO as a semi 3D tool using the tripod theory in assessing the hindfoot alignment were also demonstrated mathematically. Results: For each of these 31 cases examined, the hindfoot alignment information reflected by the FAO value was vastly different from the clinical and imaging study findings. (Table 1). Using the reference value for FAO (Normal 2.3% ± 2.9%, Varus −11.6%± 6.9%, and Valgus 11.4% ± 5.7%), 24 out of 31 cases in the cohort had a normal FAO value, however, among them there were 7 with a valgus ankle or distal tibia plus a normal or cavovarus hindfoot, 2 varus ankles with a normal hindfoot, 1 varus ankle with a valgus hindfoot, 3 cavovarus feet, 1 clubfoot, 1 equinus ankle with cavovarus foot, 2 equinus ankle with severe valgus hindfoot, 4 severe valgus hindfoot and 1 varus hindfoot with sagittal plane deformities, 2 Muller Weiss Disease; 5 out of 31 cases had a varus FAO value, but they all had a valgus ankle with either a varus hindfoot or sagittal plane deformities; 2 out of 31 cases had a valgus FAO value, however both cases had a valgus ankle with a varus hindfoot. Thorough algorithm and geometric evidence were provided. Conclusion: FAO has a very limited capacity to reflect hindfoot deformities, understandable when analyzing how the FAO is designed and measured mathematically. It is not a 3D tool. It does not include the level of the ankle nor the tibia, therefore it is not appropriate nor capable to be used as a hindfoot alignment evaluation tool. The tripod and talus projection theories cannot reflect sagittal plane deformities or coronal plane rotation, and false results are inevitably generated. Reference: 1. Lintz F, Barton T, Millet M, Harries WJ, Hepple S, Winson IG. Ground reaction force calcaneal offset: a new measurement of hindfoot alignment. Foot Ankle Surg. 2012;18(1):9-14. 2. de Cesar Netto C, Day J, Godoy-Santos AL, Roney A, Barbachan Mansur NS, Lintz F, Ellis SJ, Demetracopoulos CA. The use of three-dimensional biometric Foot and Ankle Offset to predict additional realignment procedures in total ankle replacement. Foot Ankle Surg. 2022 Feb 16:S1268-7731(22)00036-4.

Category: Trauma Introduction/Purpose: The first tarsometatarsal (TMT) joint is very crucial for midfoot stability. To address its importance, retrospective analyses of treatment for the first TMT joint dislocation with Lisfranc injury was performed in a multi-center manner. Comparison of open reduction internal fixation (ORIF) and primary arthrodesis was conducted for the injury. Methods: This multi-center study was involved ten clinical institutions in different area of China. .From January 2003 to June 2015, 126 Lisfranc injuries with first TMT joint dislocation underwent surgical intervention. Of this group, forty one (32.5%) feet were first TMT joint dislocation only. Eighty five feet were first TMT joint dislocation and fractures. They were 76 males (60.3%) and 50 females (39.7%) with a mean age of 45.5 (range, 20-87) years. The duration from injury to surgery is 11.7 (range, 4-26) days. Two groups were divided by surgery methods as open reduction internal fixation (ORIF) group and primary arthrodesis group. Ninety two patients were performed by ORIF, while primary arthrodesis group including 34 cases. Outcome measures included clinical examination, radiographs, AOFAS ankle-hindfoot scores, visual analogue scale (VAS) and SF-36 scores. Complications and revision rate were analyzed as well. Results: 126 patients were followed up for 29.5 months. At 1.5 years postoperatively, the AOFAS score was 79 and 85 in ORIF group and arthrodesis group.The VAS score was 3.1 separately in two groups.The mean Physical Functioning sores of SF-36 was 80.3 points and 83.5• points. The Bodily Pain score of SF-36 was 76.1 points and 84.6• points.Redislocation of first tarsometarsal joint were observed in 16 cases among ORIF group.36 patients in ORIF group had pain in midfoot, eight of them had persistent pain with the development of deformity or osteoarthrosis.No redislocation and no hardware failure was identified in arthrodesis group Conclusion: Primary stable arthrodesis of the first ray gives a better short and medium term outcome than open reduction and internal fixation for Lisfranc injury with the first ray dislocation. Possible complication and revision could be avoided by primary arthrodesis for dislocated first ray injuries.

Category: Midfoot/Forefoot Introduction/Purpose: Müller-Weiss disease is an uncommon osteonecrosis of the tarsal navicular of unknown etiology. Most of them could be treated by non-surgical methods. But some severe deformity and fail to conserved methods. In those cases, surgery may be a reasonable approach. Methods: From January 2005 to Septermber 2016, we treated 69 patients suffering from Müller-Weiss disease, using the surgical arthrodesis of the talonavicular joint and naviculocuneiform joint with tricortical autologous iliac crest block fixed by screws and plate. Results: All Maceira grades were included. We reviewed the medical records of the patients and took the radiological preoperative and postoperative evaluation. The preoperative and postoperative clinical functions were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot Scale. To treat Müller-Weiss disease, we introduced a surgical arthrodesis of the talonavicular joint and naviculocuneiform joint with tricortical autologous iliac crest bone block fixed by screws and plate. The median follow up was 26 months. All the feet fused solidly. The median time for complete fusion was 13 weeks. The median AOFAS ankle-hindfoot score improved from 45 points preoperatively to 86 points at last follow-up. Conclusion: The results of this series demonstrate the arthrodesis of the TNJ and NCJ with tricortical autologous iliac crest graft is a reasonable way for treatment of Müller -Weiss disease. Based on our experience with the patients, we believe that emphasis of the restoration of the length and alignment of the medial column could achieve a good outcome.

Category: Hindfoot Introduction/Purpose: The goal of this study was to discuss the outcomes of treating calcaneal fracture malunion by restoring the subtalar joint with a reconstructive osteotomy. Methods: From May 2005 to November 2016, 85 patients (88 feet) with calcaneal malunions after a displaced intraarticular calcaneal fracture were treated by osteotomy and autogenous bone graft. The subtalar joint was preserved. The mean time from initial injury to reconstructive operation was 8.9 months (95% confidence interval, 4.5-11.6 months). The displaced posterior facet was restored through a reconstructive osteotomy, whereas the bone defect in the calcaneus after reduction was filled with the lateral exostosis that had been removed, iliac bone graft was used if necessary. All patients were evaluated clinically and radiographically at a minimum of 24 months. Sixty two patients (63 feet) were followed for a mean of 45.4 months (29.0-52.3 months). Results: According to American Orthopaedic Foot & Ankle Society (AOFAS) ankle and hindfoot score, the average score was 81.6 points (95% confidence interval, 78.5-90.4 points), which was significantly higher than the preoperative assessment. Radiographs showed that Böhler’s angle, Gissane’s angle, talus declination angle, and width and height of calcaneus were improved to a great extent. Eight patients had wound edge necrosis, and 4 had superficial infection. Two patient required a subtalar fusion for subtalar arthritis at 2 years after surgery. Conclusion: Restoring the subtalar joint with a reconstructive osteotomy and autogenous bone graft was an effective treatment method for selected calcaneal fracture malunions. It reconstructed calcaneal morphology and preserved the subtalar joint.

Category: Trauma Introduction/Purpose: It is controversial for operative repair of deltoid ligament in acute ankle fractures. To investigate the indication for surgical interference and the clinical outcome about repair whole deltoid ligament rupture associating with ankle fractures. Methods: We performed multiple-center study in 4 clinical centers in 4 cities of China. From January 2006 to December 2011, of 1533 ankle fractures operated, 131 deltoid ligament rupture were identified and repaired operatively. They were 74 males and 57 females with a mean age of 37.2 years (range, 15-83 years). Clinical examination, radiographs, AOFAS ankle-hindfoot scores and visual analogue scale were used for outcome measurement. Results: All incision healed primarily. 106 patients were followed up for 12 to 72 months with the mean follow-up of 27 months. The mean time of fracture union was 14.5 weeks (range, 9-16 weeks). The mean AOFAS ankle-hindfoot score at last follow-up was 91.4 points (range, 83-100 points). The mean score of VAS was 1.2 points (range, 0-6 points). The mean score of SF-36 was 91.2 points (range, 80-96 points). There was no ankle instability and post-trauma osteoarthritis. Conclusion: This multiple-center study demonstrated that deltoid ligament repair can benefit patients with unstable ankle after fracture fixation. A reasonable clinical evaluation and surgical repair could be done, choosing an appropriate repair technique according to the site of deltoid ligament rupture.

Category: Lesser Toes Introduction/Purpose: The purpose of this study was to evaluate the clinical outcomes using a double stemmed flexible silicone prosthesis for the treatment of Freiberg disease in its late stages. Methods: The subjects consisted of 13 feet from 13 cases suffering from Freiberg disease in their late stages. They underwent double stemmed flexible silicone prosthesis replacement for metatarsophalangeal joints. The average age was 63.8 (range 30~88) years. The average follow up period was 26 (range 18–42) months. The investigation was carried out using the range of motion (ROM), visual analog scale (VAS), AOFAS and Maryland metatarsophalangeal joints scale before surgery and at the latest follow-up. Results: The average ROM of dorsal flexion improved from 39.3±6.1° before surgery to 75.4±8.6° at latest follow-up (p

Category: Midfoot/Forefoot Introduction/Purpose: To characterize clinical treatment of the malunion after midfoot injury. Methods: 22 cases of malunion following complex midfoot injury from 2004 to 2012. They were 19 men and 3 women with mean age of 37.8. The foot deformity was categorized into 3 types and 3 subtypes, with type? indicating normal foot arch (type ?a forefoot abduction, ?b forefoot adduction and Ic forefoot normal), type? Cavus deformity (subtype is same as?), and type ? flatfoot deformity (subtype is same as?) . There were 2 cases of type?a, 4 cases of type?c, 9 cases of type?a, 4 cases of type ?a, 3 cases of type ?c in our cohort. According to the malunion typing, osteotomy, joint arthrodesis, or realignment was used to correct deformity. Clinical outcomes were evaluated by AOFAS score and VAS. Results: All the patients were followed up for average 34.7 months.The mean VAS score was 2.0 points (0-6) and mean AOFAS score was 83.9±2.3 points (73-94) at the last follow-up, giving an excellent to good rate of 81.8%. All cases obtained favorable functional outcomes without bone nonunion, except one patient who still suffered from midfoot walking discomfort 3 years after operation. Conclusion: Operative management of malunion following midfoot injury is effective and good results can only be obtained by stabilizing injured joint, realignment and recover foot arch.Our typing of the midfoot malunion is helpful in the operative treatment.

Category: Ankle Introduction/Purpose: The purpose of current study was to retrospectively analyze the clinical outcomes of buttress plate treatment of posterior pilon fractures. Methods: Between January 2005 and December 2016, 58 patients with posterior pilon fractures underwent buttress plate fixation. There were 32 males and 26 females and the mean age was 40.2years (range, 23 to 73 years). Preoperative radiographs, CT scans and three dimensional reconstructions were used to evaluate the fracture patterns. On the basis of the extension of the fracture lines presented on the CT scans, a posterolateral approach or a combination of both posterolateral and posteromedial approaches were used to reduce and fixate the posterior malleolar fragments. Clinical and radiographic examinations were used for postoperative follow-up. The American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and the Visual Analogue Scale (VAS) were used to evaluate the functional outcomes. Results: According to the CT scan images, the posterior pilon fractures were classified into 3 types. 51 patients were available for follow-up. The mean time of follow-up was 44.8 months. The mean AOFAS score was 84.3 points, and the mean VAS score was 1.6 points. One patient was found with ankle joint swelling and long term walking discomfort at 2-year follow-up. Other patients received favorable functional outcomes. No hardware failure occurred. Conclusion: The clinical outcomes of buttress plate treatment of posterior pilon fractures were satisfactory. Buttress plating availed the patients to return to earlier weight-bearing and functional exercises.