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Background: The spring (calcaneonavicular) ligament provides one of the main static supports of the medial arch of the foot. The purpose of this study was to retrospectively assess the results of patients having undergone reconstruction of the spring ligament using a peroneus longus tendon autograft left at its distal atttachment and passed through the navicular followed by either a calcaneal or tibial drill hole, a technique not previously reported. Materials and Methods: Thirteen consecutive patients (14 feet) (mean age, 63.5 ± 12.3 years) undergoing flatfoot surgery with spring ligament reconstruc tion for cases in which lateral column lengthening failed to correct talonvavicular defonnity were reviewed. The AOFAS, FAOS, and SF-36 were assessed along with standard weight bearing radiographs at a followup visit at a mean of 8.9 ± 1.8 years after surgery. Hindfoot alignment and eversion strength were measured. Results: The AOFAS ankle-hindfoot subdiscore increased from 43,1 to 90.3 (P:5 0.001), The postoperative FAOS pain subscale and overall SF-36 were 83.7 (range, 67.9 to 100), and 77,3 (range 37.8 to 95.6) respectively, The AP first tarsometatarsal angle (P = 0.015), talonavicular coverage angle (P = O.(H)3), lateral calcaneal pitch (P = O.(H)2), and lateral talonavicular augle (P =0.017) improved significantly and were within nonnal ranges postoperatively. The mean hindfoot alignment measured 2.7 degrees of valgus. All but one patient had normal (5/5) eversion strength. Conclusion: Reconstruction of the spring ligament resulted in few complications and might be considered as an alternative to arthrodesis in patients with ruptures of the spring ligament and deformity that does not correct fully with bony procedures alone. [ABSTRACT FROM AUTHOR]

BACKGROUND: Procedures utilized to address the flatfoot in this study included medializing calcaneal osteotomy, posterior tibial tendon reconstruction with flexor digitorum longus tendon transfer, and in patients with more severe deformity, lateral column lengthening. We evaluated patients age 50 and less at the time of surgery, who underwent surgical reconstruction for Stage 2 posterior tibial tendon dysfunction. Pre- and postoperative activity levels were evaluated to assess the effect of surgical reconstruction in the younger patient. MATERIALS AND METHOD: Thirty-four feet in 30 patients (11 male, 19 female) with an average age of 41.2 (range, 17 to 50) years had surgery between 1997 and 2004. All feet were examined at an average followup of 44.5 (range, 24 to 65) months and were evaluated with the American-Orthopaedic-Foot and Ankle Society (AOFAS) Hindfoot-Score and SF-36 score. RESULTS: The average preoperative AOFAS-Score was 53.1 +/- 14.5 points and 83.2 +/- 12.2 points at final postoperative followup. The mean improvement was 29.5. The difference between the preoperative and postoperative AOFAS score was significant (p < 0.0001) using a two-tailed t-test. The difference in the AOFAS pain and alignment subscales was also significant (p < 0.0001). The function subscale improvement was also significant (p = 0.018). The mean physical function component of the postoperative SF-36 score was 79.2. A correlation was found between the SF-36 physical component score and the post operative AOFAS score (r(2) = 0.754). CONCLUSION: While some lateral discomfort or pain occurred in patients with or without a lateral column lengthening, the posterior tibial tendon reconstruction utilizing medial calcaneal displacement osteotomy with flexor digitorum longus transfer and a lateral column lengthening with more deformity was successful in the higher-functioning, younger patients. [ABSTRACT FROM AUTHOR]

Background: The talus is more internally rotated within the ankle mortise in progressive collapsing foot deformity (PCFD) patients. However, no studies have investigated the change in talar axial rotation (AR) in PCFD postoperatively. The primary aim was to investigate the change in talar AR following PCFD reconstruction. Secondary aims were to determine whether talar AR changes were associated with other radiographic measurements or specific procedures, and whether postoperative talar AR was associated with 2-year patient-reported outcome scores., Methods: Twenty-seven patients older than 18 years who underwent flexible PCFD reconstruction with preoperative and at least 5-month postoperative weightbearing computed tomographic (WBCT) scans and radiographs and had preoperative and at least 2-year postoperative PROMIS scores were included. Patients with talonavicular fusions were excluded. Talar AR was the angle between the transmalleolar axis and talar axis on WBCT scans, with smaller angles representing more internal rotation as described by Kim et al. Hindfoot moment arm, Meary angle, fibulocalcaneal and talocalcaneal distance, subtalar middle facet uncoverage, and talonavicular angle were measured on radiographs., Results: Postoperative talar AR was 49.7 degrees (IQR, 45.9, 57.3), which was more externally rotated than preoperative AR by a median of 8.3 degrees (IQR, 2.2, 15.7) ( P  > .001). The change in talar AR was not associated with changes in any radiographic parameter. Increasing external talar AR was associated with an increase in postoperative PROMIS pain intensity ( r s  = 0.38, 95% CI 0.00, 0.67). Lateral column lengthening and subtalar fusion procedures were not associated with changes in talar AR ( P  > .10)., Conclusion: PCFD reconstruction results in external rotation of the talus within the ankle mortise. Kim et al found that control patients had approximately 40 to 60 degrees of talar AR, which is similar to this study's corrected position of the talus. However, increasing talar external rotation resulted in worse postoperative PROMIS pain intensity, suggesting the possibility of overcorrecting the internal AR deformity., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: Isolated subtalar and talonavicular joint arthrodeses have been associated with adjacent joint arthritis and altered hindfoot kinematics during simplified loading scenarios. However, the effect on kinematics during dynamic activity is unknown. This study assessed changes in subtalar and talonavicular kinematics after isolated talonavicular (TN iso ) and subtalar (ST iso ) arthrodesis, respectively, during stance simulations., Methods: Fourteen midtibia specimens received either a TN iso or ST iso arthrodesis, with 7 randomized to each group. A 6-degree-of-freedom robot sequentially simulated the stance phase for the intact and arthrodesis conditions. Bootstrapped bias-corrected 95% CIs of the talonavicular and subtalar joint kinematics were calculated and compared between conditions., Results: The TN iso decreased subtalar inversion, adduction, and plantarflexion in late stance ( P  < .05). The subtalar range of motion in the sagittal and coronal planes decreased by 40% ( P  = .009) and 46% ( P  = .002), respectively. No significant changes in talonavicular joint kinematics were observed after isolated subtalar arthrodesis; however, the range of motion was reduced by 61% ( P  = .007) and 50% ( P  = .003) in the coronal and axial planes, respectively., Conclusion: In this model for arthrodesis, changes in subtalar kinematics and motion restriction were observed after isolated talonavicular arthrodesis, and motion restriction was observed after isolated subtalar arthrodesis. Surprisingly, talonavicular kinematics did not appear to change after isolated subtalar arthrodesis., Clinical Relevance: Both joint fusions substantially decrease the motion of the reciprocal adjacent joint. Surgeons should be aware that the collateral costs with talonavicular fusion appear higher, and it has a significant effect on subtalar kinematics during the toe-off phase of gait., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors report support for the present manuscript from a Paragon 28 research grant contract; Paragon 28 provided screws to perform the arthrodesis conditions and complete the original study that this short report expands on. Disclosure forms for all authors are available online.

Background: Although operative treatment of the flexible progressive collapsing foot deformity (PCFD) remains controversial, correction of residual forefoot varus and stabilization of the medial column are important components of reconstruction. A peroneus brevis (PB) to peroneus longus (PL) tendon transfer has been proposed to address these deformities. The aim of our study was to determine the effect of an isolated PB-to-PL transfer on medial column kinematics and plantar pressures in a simulated PCFD (sPCFD) cadaveric model., Methods: The stance phase of level walking was simulated in 10 midtibia cadaveric specimens using a validated 6-degree of freedom robot. Bone motions and plantar pressure were collected in 3 conditions: intact, sPCFD, and after PB-to-PL transfer. The PB-to-PL transfer was performed by transecting the PB and advancing the proximal stump 1 cm into the PL. Outcome measures included the change in joint rotation of the talonavicular, first naviculocuneiform, and first tarsometatarsal joints between conditions. Plantar pressure outcome measures included the maximum force, peak pressure under the first metatarsal, and the lateral-to-medial forefoot average pressure ratio., Results: Compared to the sPCFD condition, the PB-to-PL transfer resulted in significant increases in talonavicular plantarflexion and adduction of 68% and 72%, respectively, during simulated late stance phase. Talonavicular eversion also decreased in simulated late stance by 53%. Relative to the sPCFD condition, the PB-to-PL transfer also resulted in a 17% increase ( P  = .045) in maximum force and a 45-kPa increase ( P  = .038) in peak pressure under the first metatarsal, along with a medial shift in forefoot pressure., Conclusion: The results from this cadaver-based simulation suggest that the addition of a PB-to-PL transfer as part of the surgical management of the flexible PCFD may aid in correction of deformity and increase the plantarflexion force under the first metatarsal., Clinical Relevance: This study provides biomechanical evidence to support the addition of a PB-to-PL tendon transfer in the surgical treatment of flexible PCFD., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: Reduced hindfoot eversion motion has been proposed as a cause of increased lateral foot pressure following lateral column lengthening (LCL) for progressive collapsing foot deformity (PCFD). A subjective intraoperative assessment of passive eversion has been suggested to help evaluate correction; however, it is unclear how passive eversion correlates with objective measurements of foot stiffness. Our objectives were to quantify the relationship between the maximum passive eversion in hindfoot joints following LCL with plantar pressure during stance and to determine the influence of wedge size on these outcomes., Methods: Ten cadaveric specimens extending from the mid-tibia distally were tested on a 6-degrees-of-freedom robot to simulate the stance phase of level walking. Five conditions were tested: intact, simulated PCFD, and 3 LCL wedge conditions (4, 6, and 8 mm). Outcomes included the lateral-to-medial forefoot plantar pressure (LM) ratio during stance and the maximum passive eversion measured in the hindfoot joints. Simple linear regressions were performed to evaluate relationships between outcomes and wedge sizes., Results: A strong negative relationship was found between passive subtalar eversion and the LM ratio during stance (r[38] = -0.46; p = 0.0007), but not between passive talonavicular eversion and the LM ratio (r[38] = -0.02; p = 0.37). Wedge size was strongly related to subtalar eversion (r[38] = -0.77; p < 0.0001), talonavicular eversion (r[38] = -0.55; p = 0.0003), and the LM ratio (r[38] = 0.70; p < 0.0001). Increased wedge size resulted in average decreases in subtalar and talonavicular eversion of 1.0° (95% confidence interval [CI]: 0.8° to 1.3°) and 1.2° (95% CI: 0.6° to 1.6°), respectively. Increased wedge size also increased the LM ratio by 0.38 (95% CI: 0.25 to 0.50), indicating a lateral shift in plantar pressure., Conclusions: Decreased hindfoot eversion following LCL was related to increased lateral plantar pressure during stance. Increasing wedge size correlated with decreasing passive hindfoot eversion and increasing lateral plantar pressure, suggesting that intraoperative preservation of eversion motion may be important for preventing excessive lateral loading., Clinical Relevance: To avoid overcorrection or undercorrection of the deformity, hindfoot eversion assessment in addition to radiographic evaluation may be important for optimizing the amount of lengthening to achieve successful LCL., Competing Interests: Disclosure: No external funding was received for this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/H919 )., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Introduction: This study provides the first comparison of patient-reported outcomes between isolated cheilectomy (C) and cheilectomy with Moberg (CM) osteotomy for hallux rigidus., Methods: A single-center, retrospective registry search identified all patients with preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) scores who underwent cheilectomy, with and without concomitant proximal phalangeal dorsiflexion osteotomy, for hallux rigidus between January 2016 and December 2020. Because there were far fewer isolated cheilectomies (62), all C patients were compared with a commensurate number of consecutive CM cases (67) using preoperative, 1-year, and 2-year PROMIS scores for physical function, pain interference, pain intensity, global physical health, global mental health, and depression, as well as complication and revision data from a chart review. A multivariable linear regression analysis was performed to compare adjusted postoperative PROMIS scores between the 2 cohorts., Results: There were no differences between groups among the demographic and preoperative variables compared. The CM cohort reported worse pain interference scores preoperatively (P < .001) and at 1 year postoperatively (P = .01). However, the C cohort reported worse pain intensity scores preoperatively (P < .001) and at 1 year postoperatively (P < .001). Adjusted postoperative PROMIS score comparison demonstrated that the CM cohort had better 1-year postoperative pain intensity scores (P < .05). However, there were no differences between cohorts for additional PROMIS scores or complications data., Conclusion: The addition of a Moberg osteotomy does not appear to significantly change short- to medium-term outcomes of cheilectomy for hallux rigidus treatment., Levels of Evidence: Level III: Retrospective comparative study., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: SJE discloses consulting fees from Wright Medical, Vilex, and Paragon 28, as well as paid presentations for Stryker and Paragon 28. JTD discloses IP royalties from Zimmer and Arthrex, as well as stock in Wright Medical. The other authors declare no potential conflict of interest.

Background: The Infinity Total Ankle Arthroplasty (Stryker, Mahwah, NJ) is a low-profile fixed-bearing implant first introduced in 2014. Although the short-term survivorship (2-4 years follow-up) and complication rates of the Infinity TAA have been reported, there are limited midterm outcome reports. The aim of this study was to describe the survivorship and clinical outcomes of a single-center experience with the Infinity implant at minimum 5-year follow-up., Methods: Retrospective review of 65 ankles that underwent primary total ankle arthroplasty (TAA) with the Infinity implant was conducted. Mean clinical follow-up was 6.5 years (range, 5.0-8.0). Preoperative and postoperative radiographs were measured to assess tibiotalar alignment, periprosthetic lucencies, and cysts. Preoperative, 2-year, and 5-year postoperative Foot and Ankle Outcome Score (FAOS) subscores were compared to assess midterm clinical outcomes. Survivorship assessment was determined by removal of 1 or both metallic implant components., Results: Survivorship of the implant was 93.8% at final follow-up. There were 4 revisions: 2 for tibial implant loosening, 1 for talar loosening, and 1 for loosening of both components. Three of the 4 revisions occurred within the first 2 years following implantation, and the last failure occurred at 7 years postoperatively. There were 11 reoperations in 10 (15%) ankles and 3 wound complications. There were 17 ankles (26.2%) with radiographic abnormalities around the implants, including 14 cases with tibial component lucencies and 4 cases of periimplant cysts. FAOS outcome measurement showed general stability between 2 and 5 years and substantial improvement from preoperative status., Conclusion: To date this study is the largest midterm report on the Infinity total ankle prosthesis, with 65 implants at a mean follow-up of 6.5 years. We found good midterm implant survivorship, and patients experienced significant improvements in FAOS outcome scores and radiographic alignment at final follow-up., Level of Evidence: Level III, retrospective cohort study., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Jonathan T. Deland, MD, reports stock or stock options from Wright Medical Technology, Inc. Scott J. Ellis, MD, reports grants or contracts for research support and consulting fees from Wright Medical Technology, Inc; and royalties or licenses and a paid presenter for Stryker. ICMJE forms for all authors are available online.

Background: The Trabecular Metal (Zimmer Biomet, Warsaw, IN) total ankle arthroplasty (TAA) system uses a lateral approach with a fibular osteotomy to gain access to the tibiotalar joint and a sagittally curved tibial component. This is the first TAA system to laterally approach the ankle, and few studies have explored outcomes associated with this implant. This study aimed to report the 5-year clinical and radiographic outcomes as well as the survivorship of the implant., Methods: Over a 3-year period, 2 fellowship-trained foot and ankle surgeons used this implant system to treat 38 end-stage arthritic ankles. Reoperation and revision data were collected from all patients (100%) as part of the local prospective database. Patients completed the Foot and Ankle Outcome Score (FAOS) questionnaire preoperatively and at each annual follow-up visit; scores for a minimum of 5 years were available for 28 (73.7%) patients. A radiographic analysis compared postoperative coronal and sagittal alignment in weightbearing radiographs at a minimum of 5 years with that at 3 months postoperatively, as well as cyst or lucency formation, which was available for 21 patients (55.3%)., Results: At 5 years, there were 3 revisions (7.9%) and 9 reoperations (23.7%). Reoperations included 4 fibular hardware removal and 5 medial gutter debridement procedures. The FAOS significantly improved for all domains (P < .05). Implant positioning did not significantly change between 3 months and 5 years postoperatively., Conclusion: Our 5-year results in this small series using this unique prosthesis showed good overall survivorship (92.1%) and a reoperation rate of 23.7%, along with clinically significant improvement in patient-reported outcomes., Levels of Evidence: Level IV: Retrospective case series.

Background: Spring ligament reconstruction (SLR) has been suggested as an adjunct to other reconstructive procedures to potentially avoid talonavicular joint fusion in progressive collapsing foot deformity (PCFD) with severe abduction deformity. Most clinical reports present short-term follow-up data and a small number of patients. The purpose of this study was to examine the medium- to long-term outcomes of an SLR using allograft tendon augmentation as part of PCFD surgical reconstruction. This study to our knowledge represents the largest number of patients and the longest follow-up to date., Methods: This study retrospectively reviewed 26 patients (27 feet, mean age of 61.4 years) who underwent SLR with allograft tendon as part of PCFD reconstruction. The mean follow-up of the cohort was 8 years (range, 5-13.4). Radiographic evaluation consisted of 5 parameters including talonavicular coverage angle (TNC), with the maintenance of correction being evaluated by comparing parameters from the early postoperative period (mean: 11.6 months, range, 8-17) to final follow-up. Foot and Ankle Outcome Score (FAOS) and patient satisfaction questionnaires were collected at final follow-up. Conversion to talonavicular or subtalar fusion was considered as a failure., Results: Final radiographs demonstrated successful abduction correction, with the mean TNC improving from 43.7 degrees preoperatively to 14.1 degrees postoperatively (P < .0001). All other radiographic parameters improved significantly and exhibited maintenance of the correction. All FAOS subscales showed significant improvement. Responses to the satisfaction questionnaire were received from all except 1 patient, of whom 88.5% (23/26) were satisfied with the results, 96.2% (25/26) would undergo the surgery again, and 88.5% (23/26) would recommend the surgery. Eight feet (29.6%) required painful hardware removal and 1 (3.7%) developed nonunion of the lateral column lengthening osteotomy. No patient required conversion to talonavicular or subtalar fusion., Conclusion: This study demonstrates favorable medium- to long-term outcomes following PCFD reconstruction including an SLR with allograft tendon augmentation., Level of Evidence: Level IV, case series.

Adult tendons are highly differentiated. In mature individuals, tendon healing after an injury occurs through fibrotic tissue formation. Understanding the intrinsic reparative properties of fetal tendons would help to understand the maturation tissue process and tendon tissue repair. The present study evaluated the evolution of histoarchitecture, cellularity and the distribution of collagens I, III and V in the posterior tibial tendon in human fetuses at different gestational ages. Morphological profiles were assessed in nine fresh spontaneously aborted fetuses (Group I: five fetuses aged between 22 and 28 weeks of gestation; Group II: four fetuses aged between 32 and 38 weeks of gestation), characterized by a combination of histology, fluorescence and immunohistochemistry. In Group I, the posterior tibial tendon showed statistically significant greater cellularity and presence of collagen III and V than in Group II tendon, which showed a predominance of collagenous I and a better organization of the extracellular matrix compared with Group I tendons. In addition, a statistically significant higher rate of CD90, a marker of mesenchymal cells, was found in Group I tendons. In fetuses with gestational age between 22 and 28 weeks, the posterior tibialis tendons showed a thin and disorganized fibrillar structure, with an increase in collagen III and V fibers and mesenchymal cells. In the posterior tibialis tendons of fetuses with gestational age between 32 and 38 weeks, the fibrillar structure was thicker with a statistically significant increase in type I collagen and decreased cellularity., (© 2022. The Author(s).)

Background: The modified Lapidus procedure (first metatarso-cuneiform fusion) is a powerful technique for correcting triplanar deformity in hallux valgus. Although traditionally fixed with cross-screws (CS), growing awareness of intercuneiform stability and pronation deformity has led to fixation using a plate and first metatarsal-second cuneiform (1MT-2C) screw fixation (PS). We investigated Lapidus patient cohorts using CS vs PS fixation to understand patient-reported outcomes, angular and rotational correction, and complication rates., Methods: We retrospectively reviewed cases of modified Lapidus for hallux valgus by a single surgeon. Patients were divided into CS or PS groups according to fixation. All patients had preoperative Patient Reported Outcome Measurement Information System (PROMIS) scores and minimum 12 months of follow-up. PROMIS scores in 6 key domains were compared within and between groups. Radiographic assessment of hallux valgus angle and intermetatarsal angle were performed on pre- and postoperative XR. Pronation of the first ray was measured on pre- and postoperative weightbearing computed tomography., Results: We compared 42 patients with PS fixation to 43 with CS fixation. Both groups had significant improvement in hallux valgus angle and intermetatarsal angle ( P < .001), with no difference between groups. PS patients experienced a greater correction of first metatarsal pronation, an average reduction of 11 degrees, compared to 8 degrees in the CS group ( P < .039). Both cohorts experienced improvement in PROMIS physical function, pain interference, pain intensity, and global physical function. There were no differences in PROMIS score improvements between the cohorts. The CS group started weightbearing at 6 weeks vs 3.6 weeks for the PS group. Complication and revision rates were similar., Conclusion: A plate and 1MT-2C screw fixation provides safe, robust fixation of Lapidus procedure and prevents instability through the intercuneiform joint. We observed similar improvement in PROMIS compared with patients treated with cross-screws. Complications did not increase despite the PS group weightbearing much earlier. PS patients achieved greater first ray rotational correction., Level of Evidence: Level III, retrospective cohort study., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Scott J. Ellis, MD, reports consulting fees; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events; and participation on a data safety monitoring board or advisory board from Stryker/Wright Medical. ICMJE forms for all authors are available online., (© The Author(s) 2022.)

Background: Osteochondral autograft transplant (OAT) is often used to treat large osteochondral lesions of the talus and is generally associated with good outcomes. The addition of adjuncts such as cartilage extracellular matrix with bone marrow aspirate concentrate (ECM-BMAC) may further improve the OAT procedure but have not been thoroughly studied. We hypothesized that the placement of ECM-BMAC around the OAT graft would improve radiographic and patient-reported outcomes following OAT., Methods: Patients who received OAT, with ECM-BMAC or BMAC alone, were screened and their charts were reviewed. For patients who did receive ECM-BMAC, the mixture was spread around the edges of the OAT plug and into any surrounding areas of cartilage damage. Survey and radiographic data were collected. Average follow-up in both groups was over 2 years. Magnetic resonance imaging scans were scored using the Magnetic Resonance Observation of Cartilage Tissue (MOCART) system. Outcomes were compared statistically between groups., Results: Patients treated with ECM-BMAC (n = 34) demonstrated significantly greater improvement of scores in the FAOS categories Symptoms (17 vs -3; P = .02) and Sports Activities (40 vs 7; P = .02), and the MOCART category Subchondral Lamina ( P = .008) compared to those treated with BMAC alone (n = 30). They also experienced significantly lower rates of postoperative cysts (53% vs 18%, P = .04) and edema (94% vs 59%, P = .02)., Conclusion: The addition of ECM-BMAC to OAT was associated with improved imaging and clinical outcomes compared to OAT with BMAC alone.

Background : Previous literature suggests that patients treated with total ankle arthroplasty (TAA) versus ankle arthrodesis (AA) may have better function and lower risk for adjacent joint arthritis in the foot. Little is known on how these interventions affect proximal joints such as the knee. Questions : We sought to assess whether patients with TAA and AA exhibited altered biomechanics linked to the onset and progression of knee osteoarthritis (KOA). We used the knee adduction moment (KAM), a surrogate measure for the mechanical load experienced at the medial tibiofemoral compartment, because it is linked with the onset and progression of KOA. Methods : At a minimum of 2 years postoperatively, instrumented 3-dimensional walking gait was recorded in 10 TAA and 10 AA patients at self-selected walking speeds. TAA patients had either a Salto Talaris or INBONE prosthesis. Average first and second peak KAMs (Nm/kg), KAM impulse (Nm-s/kg), and range-of-motion (ROM, °) were calculated on both the affected and unaffected limbs for each patient. Results : There were no significant differences in the KAM's first and second peaks, impulse, or knee ROM in any plane between the unaffected and affected limbs, or between TAA and AA. Conclusion : TAA and AA may not meaningfully affect ipsilateral knee kinetics and KAMs in short-term follow-up. This study highlights the importance of continuing to study these parameters in larger cohorts of patients with longer follow-up to determine how our treatment of end-stage ankle arthritis may affect the incidence or progression of ipsilateral KOA., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Constantine A. Demetracopoulos, MD, reports relationships with Wright Medical, Integra LifeSciences, Stryker, and RTI Surgical. Jonathan T. Deland, MD, reports relationships with Arthrex and Zimmer. Cesar de Cesar Netto, MD, reports relationships with Curvebeam and Ossio. Guilherme H. Saito, MD, reports relationships with Wright Medical. Scott J. Ellis, MD, reports relationships with Wright Medical and Paragon 28. The other authors report no potential conflicts of interest., (© The Author(s) 2021.)

The foot is a highly complex biomechanical system for which finite element (FE) modeling has been used to evaluate its loading environment. However, there is limited knowledge of first metatarsophalangeal (MTP) and first metatarsocuneiform (MTC) joint contact mechanics. Our goal was to develop a framework for FE modeling of the medial forefoot which could accurately predict experimental measurements of first MTP and first MTC joint loading. Simulations of planus and rectus foot types were conducted for midstance of gait. A custom-built force-controlled cadaveric test-rig was used to derive intracapsular pressure sensor measurements of contact pressure, force, and area during quasi-static loading. The FE model was driven under the same boundary and loading conditions as the cadaver. Mesh sensitivity analyses and best-fit calibrations of moduli for first MTP and first MTC joint cartilage were performed. Consistent with previous experimental research, a lower compressive modulus was best-fit to the first MTP compared to first MTC joint at 10 MPa and 20 MPa, respectively. Mean errors in contact pressures, forces, and areas were 24%, 4%, and 40% at the first MTP joint and 23%, 12%, and 19% at the first MTC joint, respectively. The present developmental framework may provide a basis for future modeling of first MTP and first MTC joint contact mechanics. This study acts as a precursor to validation of realistic physiological loading across gait to investigate joint loading, foot type biomechanics, and surgical interventions of the medial forefoot., (Copyright © 2022 by ASME.)

Background: Digitally reconstructed radiographs (DRRs) generated from weightbearing computed tomography (WBCT) may potentially substitute for weightbearing plain radiographs (XRs) but have not been clinically validated. This study aims to test the reliability of 6 radiographic parameters of progressive collapsing foot deformity (PCFD) as measured on DRR, to investigate whether DRR represents comparably to XR through the same measurements, and to compare agreement of DRR and XR measurements of a standardized arch height parameter with reference measurements made on WBCT., Methods: DRR generated from preoperative WBCT of 71 patients (72 feet) treated surgically for PCFD were retrospectively compared with preoperative weight-bearing XR after exclusion criteria were applied. Six radiographic measurements were performed, including Meary angle, calcaneal pitch (CPA), medial cuneiform height (MCH), AP talar-first metatarsal angle (T-1MT), talonavicular coverage (TNCA), and talar incongruency (TIA). Arch height was measured on XR, DRR, and WBCT using a validated, standardized, navicular-based index. Intraclass correlation coefficients assessed DRR intraobserver and interobserver reliability. Paired samples t tests tested differences between XR and DRR. Bland-Altman limits of agreement analysis compared DRR and XR agreement with WBCT measurements., Results: Measurements were within standard PCFD ranges on XR and DRR. All measurements demonstrated excellent intrarater reliability and good to excellent interrater agreement, consistent with previous literature on XR. No differences were found for Meary, CPA, or TNCA. Minor differences were observed for MCH, T-1MT, and TIA. DRR measurements demonstrated greater agreement with WBCT than XR measurements., Conclusion: DRR from WBCT may be a promising substitute for XR in the clinical evaluation of PCFD. Radiographic measurements made on DRR demonstrated good to excellent reliability. Although small differences were found between XR and DRR for certain measurements, DRR more accurately represented medial arch anatomy compared to gold standard WBCT data than XR. If validated as a clinical substitute, DRR could eventually obviate XR where WBCT is available., Level of Evidence: Level III, retrospective cohort study.

Background: Progressive collapsing foot deformity (PCFD) is a debilitating condition encompassing several interrelated, progressive deformities requiring a combination of reconstructive procedures. Few studies investigate returns to activity following flatfoot reconstruction, and existing studies only examine 1 or 2 of the numerous procedures employed. This study aims to provide the first generalizable assessment of returns to sports and physical activity following reconstruction surgery in patients with flexible flatfoot deformity., Methods: Patients aged 18-60 years who underwent reconstructive surgery between February 16 and May 19 for symptomatic flexible-stage flatfoot deformity were identified by registry review. Eighty-two of 113 eligible patients (73%) were reached at a mean 2.9 years (range, 2.0-5.4) of follow-up with mean age at surgery of 48.9 years (range, 18-59). Returns to physical activity were evaluated with a sports-specific survey. Clinical outcomes were evaluated with Patient-Reported Outcomes Measurement Information System (PROMIS) scores., Results: Patients reported participation in 21 specific sports and activities. One-fourth (25.6%) of patients (21/82) reported increased difficulty with physical activities postoperatively, 15.9% reported equal difficulty, and 58.5% (48/82) reported decreased difficulty. Median return times were 9-12 months for participation and 12-18 months to reach maximum preoperative participation levels. Improvements in Physical Function ( P = .001), Pain Interference ( P < .001), Pain Intensity ( P <.001), and Global Physical Health ( P = .004) were associated with increased satisfaction with respect to sports and physical activities., Discussion: This study investigated participation in specific sports and physical activities following flatfoot reconstruction. Our findings suggest mixed outcomes, where many patients reported life-changing improvements but many also experienced prolonged pain and difficulty after surgery. Some patients reported increased difficulty or inability to return to their preoperative maximum level of participation, indicating that flatfoot reconstructions can lead to athletic limitations., Conclusion: Although flatfoot reconstruction can be a powerful tool to increase patients' capacity to engage in physical activity, in our cohort many patients had reduced physical activity outcomes., Level of Evidence: Level IV, retrospective case series.

Background: The use of total ankle arthroplasty (TAA) in the treatment of ankle arthritis has grown substantially as advancements are made in design and surgical technique. Among the criteria guiding the choice between arthroplasty and arthrodesis, the long-term survival and postoperative outcomes are of crucial importance. Although outcomes of the INBONE I have been published, there is limited midterm survival data for the INBONE II. The purpose of this study was to determine the radiographic and patient-reported outcomes, and survivorship of this prosthesis in patients with a minimum 5-year follow-up., Methods: We retrospectively identified 51 ankles (46 patients) from 2010 to 2015 who underwent TAA with the INBONE II prosthesis at our institution. Of these, 44 cases had minimum clinical follow-up of 5 years (mean, 6.4; range 5-9). Median age was 66 years (range 42-81) and median BMI was 27.5 (range 20.1-33.0). A chart review was performed to record the incidence of revision and reoperation. Preoperative and postoperative radiographs were analyzed to assess the coronal tibiotalar alignment (TTA), the talar inclination angle, and the presence of periprosthetic lucencies and cyst formation. Preoperative and minimum 5-year postoperative Foot and Ankle Outcome Score (FAOS) subscales were compared. Survivorship was determined by incidence of revision, defined as removal of a metallic component., Results: The survivorship at 5 years was 98% and the rate of reoperation was 7.8% (n = 4); 2 patients underwent irrigation and debridement for infection, 1 patient underwent a medializing calcaneal osteotomy, and 1 patient underwent open gutter debridement, 1 patient underwent a revision of a subsided talar component at 3.2 years after index surgery. Average postoperative TTA was 88.6 degrees, with 42 rated as neutral (85-95 degrees), 2 varus (<85 degrees), and no valgus (>95 degrees) ankles. At final follow-up, asymptomatic periprosthetic cysts were observed in 8 patients. All FAOS domain scores improved between preoperative and final follow-up., Conclusion: At midterm follow-up, we observed significant improvement in radiographic alignment and patient-reported outcome scores for the INBONE II total ankle prosthesis. In addition, this cohort has had a relatively low reoperation rate and high survivorship., Level of Evidence: Level IV, case series.

Background: Many foot pathologies have been associated with foot type. However, the association of first ray hypermobility remains enigmatic. The purpose of this study was to investigate first ray hypermobility among participants with planus and rectus foot types and its influence on static measures of foot structure., Methods: Twenty asymptomatic participants with planus (n = 23 feet) and rectus (n = 17 feet) foot types were enrolled. Several parameters of static foot structure (arch height index, arch height flexibility, first metatarsophalangeal joint flexibility, and first ray mobility) were measured. Participants were further stratified into groups with nonhypermobile (n = 26 feet) and hypermobile (n = 14 feet) first rays. First ray mobility ≥ 8 mm was used to define "first ray hypermobility". Generalized estimating equations, best-fit regression lines, and stepwise linear regression were used to identify significant differences and predictors between the study variables., Results: Overall, 86% of subjects categorized with first ray hypermobility exhibited a planus foot type. Arch height flexibility, weightbearing first ray mobility, and first metatarsophalangeal joint flexibility showed no significant between-group differences. However, weightbearing ray mobility and first metatarsophalangeal joint laxity were associated with partial weightbearing first ray mobility, accounting for 38% of the model variance., Conclusion: The planus foot type was found to be associated with first ray hypermobility. Furthermore, weightbearing first ray mobility and first metatarsophalangeal joint laxity were predictive of partial weightbearing first ray mobility, demonstrating an interaction between the translation and rotational mechanics of the first ray., Clinical Relevance: Association of first ray hypermobility with foot type and first metatarsophalangeal joint flexibility may help understand the sequela to symptomatic pathologies of the foot., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors report a patent (62/990,816) pending. ICMJE forms for all authors are available online., (© The Author(s) 2022.)

Background: Quantifying first ray mobility is crucial to understand aberrant foot biomechanics. A novel device (MAP1 st ) that can perform measurements of first ray mobility in different weightbearing conditions, foot alignments, and normalization was tested. The reliability of these measurement techniques was assessed in comparison to a handheld ruler considered representative of the common clinical examination., Methods: The study included 25 participants (50 feet). Two independent raters performed baseline, test-retest, and remove-replace measurements of first ray mobility with MAP1 st and the handheld device. The effects of non-, partial, and full weightbearing in subtalar joint neutral and the resting calcaneal stance position were assessed. Measurement normalization relative to foot size was also investigated. Intra- and interclass correlation coefficients (ICCs) were calculated for each device between the 2 raters. In addition, Bland-Altman plots were constructed to determine if fixed biases or substantial outliers were present., Results: Similar intrarater ICC values were found for both devices (≥0.85). However, interrater ICC values were substantially improved by MAP1 st compared with the handheld device (0.58 vs 0.06). Bland-Altman plots demonstrated biases of 1.27 mm for the handheld ruler, and 2.88 to 0.05 mm and -1.16 to 0.00 for linear and normalized MAP1 st measurements, respectively. Improved reliability was achieved with MAP1 st for normalized assessments of first ray mobility while the foot was placed in partial- and full-weightbearing resting calcaneal stance positions., Conclusion: MAP1 st provided reliable assessments of partial- and full-weightbearing first ray mobility. It should help investigators to explore the potential relationships between first ray function and aberrant foot biomechanics in future research., Level of Evidence: Level II, prospective cohort study.

Background: There is no current consensus on whether to use an open or minimally invasive (MIS) approach for Achilles tendon repair after acute rupture. We hypothesized that patients in both open and MIS groups would have improved patient-reported outcome scores using the PROMIS system postoperatively, but that there would be minimal differences in these scores and complication rates between operative techniques., Methods: A total of 185 patients who underwent surgery for an acute, unilateral Achilles tendon rupture between January 2016 and June 2019, with minimum 1-year follow-up were included in the cohort studied. The minimally invasive group was defined by use of a commercially available minimally invasive device through a smaller surgical incision (n=118). The open repair group did not use the device, and suture repair was performed through larger surgical incisions (n=67). Postoperative protocols were similar between groups. Preoperative and postoperative PROMIS scores were collected prospectively through our institution's registry. Demographics and complications were recorded., Results: PROMIS scores overall improved in both study groups after operative repair. No significant differences in postoperative PROMIS scores were observed between the open and MIS repair groups. There were also no significant differences in complication rates between groups. Overall, 19.5% of patients in the MIS group had at least 1 postoperative complication (8.5% deep vein thrombosis [DVT], 3.3% rerupture, 1.7% sural nerve injury, 2.5% infection), compared to 16.4% in the open group (9.0% DVT, 1.5% rerupture, 1.5% sural nerve injury, 0% infection)., Conclusion: Patients undergoing either minimally invasive or open Achilles tendon repair after acute rupture have similar PROMIS outcomes and complication types and incidences., Level of Evidence: Level III, retrospective cohort study., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Jonathan T. Deland, MD, reports personal fees from Arthrex. ICMJE forms for all authors are available online., (© The Author(s) 2021.)

Background: Weightbearing cone beam computed tomography (WBCT) has been gaining traction as a useful imaging modality in the diagnosis and follow-up of foot and ankle musculoskeletal pathologies due to the ability to perform quick, low-dose, 3-dimensional (3D) scans. However, the resulting wealth of 3D data renders daily clinical use time-consuming. The aim of this study was to evaluate a new artificial intelligence (AI)-based automatic measurement for the M1-M2 intermetatarsal angle (IMA) in hallux valgus (HV). We hypothesized that automatic and manual measurements would have a strong correlation, and that the AI software would yield better reproducibility and would be faster compared with manual measurements., Methods: This was a multicenter retrospective comparative case-control study in which a total of 128 feet were included from 93 patients who underwent WBCT scans as part of their routine follow-up: 59 feet with symptomatic HV and 69 controls. The IMA was measured automatically using the AI software and manually on digitally reconstructed radiographs (DRRs). The AI software produced both an automatic 2D (auto 2D) and 3D (auto 3D) measurement., Results: There were strong intermethod correlations between the DRR IMA and the auto 2D (HV, r = 0.61; control, r = 0.60; all P < .0001) and auto 3D (HV, r = 0.63; control, r = 0.52; all P < .0001) measurements, respectively. The intrasoftware reproducibility was very close to 100%. Measurements took 23.6 ± 2.31 seconds and 14.5 ± 1.18 seconds, respectively, when taken manually on DRRs and automatically. Controls demonstrated a mean DRR IMA of 8.6 (95% CI, 8.1-9.1), mean auto 2D of 11.2 (95% CI, 10.7-11.7), and mean auto 3D IMA of 11.0 (95% CI, 10.5-11.5). The HV group demonstrated significantly increased IMA compared with controls ( P < .0001), with a mean DRR IMA of 15.4 (95% CI, 14.8-16.1), mean auto 2D of 17.8 (95% CI, 17.2-18.4), and mean auto 3D IMA of 16.8 (95% CI, 16.8-17.4)., Conclusion: Measurements generated by the WBCT AI-based automatic measurement system for IMA demonstrated strong correlations with manual measurements, with near-perfect reproducibility. Further developments are warranted in order to make this tool more usable in daily practice, particularly with respect to its use in the presence of hardware in the foot., Level of Evidence: Level III, retrospective comparative study.

Background: Despite good evidence that supports significant improvements in pain and physical function following a total ankle replacement (TAR) for end-stage ankle arthritis, there is a subset of patients who do not significantly benefit from surgery. The purpose of this study was to perform a preliminary analysis to determine if preoperative Patient-Reported Outcome Measurement Information System (PROMIS) scores could be used to predict which patients were at risk of not meaningfully improving following a TAR., Methods: Prospectively collected preoperative and ≥2-year postoperative PROMIS physical function, pain interference, pain intensity, and depression scores for 111 feet in 105 patients were included in the study. Significant postoperative improvement was defined using minimal clinically important differences (MCIDs). Logistic regression models and area under the curve (AUC) analyses were used to determine whether preoperative PROMIS scores were predictive of postoperative outcomes., Results: Receiver operating characteristic curves found statistically significant AUCs for the PROMIS physical function (AUC = 0.728, P = .004), pain intensity (AUC = 0.720, P = .018), and depression (AUC = 0.761, P < .001) domains. The preoperative PROMIS pain interference domain did not achieve a statistically significant AUC., Conclusion: Preoperative PROMIS physical function and pain intensity t scores may be used to predict postoperative improvement in patients following a fixed-bearing TAR; however, preoperative PROMIS pain interference scores were not good predictors. The results of this study may be used to guide research regarding patient-reported outcomes following TAR., Level of Evidence: Level III, retrospective comparative series., Competing Interests: 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. ICMJE forms for all authors are available online., (© The Author(s) 2021.)

Background: Microfracture (MF) has been used historically to treat osteochondral lesions of the talus (OLTs), with favorable outcomes reported in approximately 80% to 85% of cases. However, MF repairs have been shown to degrade over time at long-term follow-up, suggesting that further study into optimal OLT treatment is warranted. The use of adjuvant extracellular matrix with bone marrow aspirate concentrate (ECM-BMAC) has not been extensively evaluated in the literature. We present a comparison of patient-reported and radiographic outcomes following ECM-BMAC repair vs traditional MF., Methods: Patients who underwent MF (n = 67) or ECM-BMAC (n = 62) treatment for an OLT were identified and their charts were retrospectively reviewed. Postoperative magnetic resonance imaging (MRI) was evaluated and patient-reported outcome scores, either Foot and Ankle Outcome Scores (FAOS) or Patient-Reported Measurement Information System (PROMIS) scores, were collected. MRIs were scored by a radiologist, fellowship trained in musculoskeletal radiology, using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) system. Radiographic and clinical outcomes were compared between groups., Results: On average, patients treated with ECM-BMAC demonstrated a higher total MOCART score compared to the MF group (73 ± SD 11.5 vs 54.0 ± 24.1; P = .0015). ECM-BMAC patients also had significantly better scores for the Infill, Integration, and Signal MOCART subcategories. Last, patients treated with ECM-BMAC had a lower rate of revision compared to those treated with MF (4.8% vs 20.9%; P = .007). FAOS scores were compared between groups, with no significant differences observed., Conclusion: When comparing outcomes between patients treated for an OLT with ECM-BMAC vs traditional MF, we observed superior MRI results for ECM-BMAC patients. The rate of revision surgery was higher for MF patients, although patient-reported outcomes were similar between groups. The use of ECM-BMAC as an adjuvant therapy in the treatment of OLTs may result in improved reparative tissue when compared to MF., Level of Evidence: Level III, comparative series.

Background: Historically, microfracture has been used to treat small talar osteochondral lesions with good results, whereas osteochondral autologous transplantation (OAT) has proven effective for the treatment of larger lesions. It is not clear which method is more effective for medium-sized lesions around the critical size of 150 mm 2 , above which microfracture outcomes tend to be poor. The purpose of this study was to determine the potential advantages of OAT augmented with a combination of extracellular matrix and bone marrow aspirate concentrate (ECM-BMAC) compared to debridement with ECM-BMAC (DEB) in the treatment of medium-sized osteochondral lesions of the talus (OLTs)., Methods: Clinical and radiographic data were collected retrospectively for patients treated by a single fellowship-trained foot and ankle surgeon. Magnetic resonance images (MRIs) were scored using the Magnetic Resonance Observation of Cartilage Tissue (MOCART) system and were evaluated for the presence of cysts and edema. Fifty-two patients met inclusion criteria, with 25 who received an OAT procedure. Age, body mass index, lesion size, lesion location, and follow-up time were similar between groups. Average MRI follow-up times were 16.7 months for the OAT group and 20.3 months for the DEB group ( P = .38)., Results: Patients treated with OAT had significantly higher average total MOCART scores (69 vs 55, P = .04) and significantly lower rates of cyst (14% vs 55%, P < .01), edema (59% vs 90%, P = .04), revision surgery (0% vs 19%, P = .05), and therapeutic injection for pain (4% vs 30%, P = .02) compared to patients treated with DEB. No significant differences were detected in patient-reported outcome scores between groups., Conclusion: The native hyaline cartilage introduced by OAT appears to result in higher-quality repair tissue when compared to DEB, as evidenced by OAT patients' higher MOCART scores and lower rates of cyst and edema. There was no difference in clinical outcome scores, though OAT patients did not require revision surgery or therapeutic injection for pain as frequently as DEB patients., Level of Evidence: Level III, retrospective comparative study.

Background: Previous studies have demonstrated that procedure-specific thresholds using preoperative patient-reported outcome scores may be used to predict postoperative outcomes. The primary purpose of this study was to determine if preoperative Patient-Reported Outcomes Measurement Information System (PROMIS) thresholds could be used to predict which patients would clinically improve at 2 years postoperatively following reconstruction of their flexible adult-acquired flatfoot deformity (AAFD)., Methods: PROMIS physical function, pain interference, and depression scores were prospectively collected preoperatively and at a minimum of 2 years postoperatively for 75 feet with flexible AAFD. Minimal clinically important differences (MCIDs) were calculated to establish significant postoperative improvement. Receiver operating characteristic curves and area under the curve analyses were employed to determine whether preoperative PROMIS scores could be used to predict postoperative outcomes., Results: The PROMIS physical function receiver operating characteristic curve analysis (area under the curve = 0.913, P < .001) found that a preoperative PROMIS physical function score greater than 45.7 resulted in a 14.3% probability of achieving the MCID, whereas a preoperative score of less than 40.8 had a 97.7% probability of achieving the MCID. A preoperative PROMIS pain interference score (area under the curve = 0.799, P < .001) less than 54.1 had only a 23.1% probability of achieving the MCID at 2 years postoperatively., Conclusions: Preoperative PROMIS physical function and pain interference scores could be used to predict postoperative improvement in patients with flexible AAFD. These results may help surgeons counsel patients regarding the anticipated benefit of surgery., Level of Evidence: Level III, retrospective comparative series.

In total ankle arthroplasty, the interaction at the joint between implant and bone is driven by a complex loading environment. Unfortunately, little is known about the loads at the ankle during daily activities since earlier attempts use two- or three-dimensional models to explore simplified joint mechanics. Our goal was to develop a framework to calculate multi-axial loads at the joint during simulated level walking following total ankle arthroplasty. To accomplish this, we combined robotic simulations of level walking at one-quarter bodyweight in three cadaveric foot and ankle specimens with musculoskeletal modeling to calculate the multi-axial forces and moments at the ankle during the stance phase. The peak compressive forces calculated were between 720 and 873 N occurring around 77%-80% of stance. The peak moment, which was the internal moment for all specimens, was between 6.1 and 11.6 N m and occurred between 72% and 88% of the stance phase. The peak moment did not necessarily occur with the peak force. The ankle joint loads calculated in this study correspond well to previous attempts in the literature; however, our robotic simulator and framework provide an opportunity to resolve the resultant three-dimensional forces and moments as others have not in previous studies. The framework may be useful to calculate ankle joint loads in cadaveric specimens as the first step in evaluating bone-implant interactions in total ankle replacement using specimen specific inputs. This approach also provides a unique opportunity to evaluate changes in joint loads and kinematics following surgical interventions of the foot and ankle., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Finite element (FE) models to evaluate the burden placed on the interaction between total ankle arthroplasty (TAA) implants and the bone often rely on peak axial forces. However, the loading environment of the ankle is complex, and it is unclear whether peak axial forces represent a challenging scenario for the interaction between the implant and the bone. Our goal was to determine how the loads and the design of the fixation of the tibial component of TAA impact the interaction between the implant and the bone. To this end, we developed a framework that integrated robotic cadaveric simulations to determine the ankle kinematics, musculoskeletal models to determine the ankle joint loads, and FE models to evaluate the interaction between TAA and the bone. We compared the bone-implant micromotion and the risk of bone failure of three common fixation designs for the tibial component of TAA: spikes, a stem, and a keel. We found that the most critical conditions for the interaction between the implant and the bone were dependent on the specimen and the fixation design, but always involved submaximal forces and large moments. We also found that while the fixation design influenced the distribution and the peak value of bone-implant micromotion, the amount of bone at risk of failure was specimen dependent. To account for the most critical conditions for the interaction between the implant and the bone, our results support simulating multiple specimens under complex loading profiles that include multiaxial moments and span entire activity cycles., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: The Salto Talaris is a fixed-bearing implant first approved in the US in 2006. While early surgical outcomes have been promising, mid- to long-term survivorship data are limited. The aim of this study was to present the survivorship and causes of failure of the Salto Talaris implant, with functional and radiographic outcomes., Methods: Eighty-seven prospectively followed patients who underwent total ankle arthroplasty with the Salto Talaris between 2007 and 2015 at our institution were retrospectively identified. Of these, 82 patients (85 ankles) had a minimum follow-up of 5 (mean, 7.1; range, 5-12) years. The mean age was 63.5 (range, 42-82) years and the mean body mass index was 28.1 (range, 17.9-41.2) kg/m 2 . Survivorship was determined by incidence of revision, defined as removal/exchange of a metal component. Preoperative, immediate, and minimum 5-year postoperative AP and lateral weightbearing radiographs were reviewed; tibiotalar alignment (TTA) and the medial distal tibial angle (MDTA) were measured to assess coronal talar and tibial alignment, respectively. The sagittal tibial angle (STA) was measured; the talar inclination angle (TIA) was measured to evaluate for radiographic subsidence of the implant, defined as a change in TIA of 5 degrees or more from the immediately to the latest postoperative lateral radiograph. The locations of periprosthetic cysts were documented. Preoperative and minimum 5-year postoperative Foot and Ankle Outcome Score (FAOS) subscales were compared., Results: Survivorship was 97.6% with 2 revisions. One patient underwent tibial and talar component revision for varus malalignment of the ankle; another underwent talar component revision for aseptic loosening and subsidence. The rate of other reoperations was 21.2% ( n = 18), with the main reoperation being exostectomy with debridement for ankle impingement ( n = 12). At final follow-up, the average TTA improved 4.4 (± 3.8) degrees, the average MDTA improved 3.4 (± 2.6) degrees, and the average STA improved 5.3 (± 4.5) degrees. Periprosthetic cysts were observed in 18 patients, and there was no radiographic subsidence. All FAOS subscales demonstrated significant improvement at final follow-up., Conclusions: We found the Salto Talaris implant to be durable, consistent with previous studies of shorter follow-up lengths. We observed significant improvement in radiographic alignment as well as patient-reported clinical outcomes at a minimum 5-year follow-up., Level of Evidence: Level IV, retrospective case series.

Recommendation: There is evidence supporting medial soft tissue reconstruction, such as spring and deltoid ligament reconstructions, in the treatment of severe progressive collapsing foot deformity (PCFD). We recommend spring ligament reconstruction to be considered in addition to lateral column lengthening or subtalar fusion at the initial operation when those procedures have given at least 50% correction but inadequate correction of the severe flexible subluxation of the talonavicular and subtalar joints. We also recommend combined flatfoot reconstruction and deltoid reconstruction be considered as a joint sparing alternative in the presence of PCFD with valgus deformity of the ankle joint if there is 50% or more of the lateral joint space remaining., Level of Evidence: Level V, expert opinion.

Recommendation: Forefoot varus is a physical and radiographic examination finding associated with the Progressive Collapsing Foot Deformity (PCFD). Varus position of the forefoot relative to the hindfoot is caused by medial midfoot collapse with apex plantar angulation of the medial column. Some surgeons use the term forefoot supination to describe this same deformity (see Introduction section with nomenclature). Correction of this deformity is important to restore the weightbearing tripod of the foot and help resist a recurrence of foot collapse. When the forefoot varus deformity is isolated to the medial metatarsal and medial cuneiform, correction is indicated with an opening wedge medial cuneiform (Cotton) osteotomy, typically with interposition of an allograft bone wedge from 5 to 11 mm in width at the base. When the forefoot varus is global, involving varus angulation of the entire forefoot and midfoot relative to the hindfoot, other procedures are needed to adequately correct the deformity., Level of Evidence: Level V, consensus, expert opinion.

Recommendation: There is evidence indicating that the amount of bony correction performed in the setting of progressive collapsing foot deformity reconstructive surgery can be titrated within a recommended range for a variety of procedures. The typical range when performing a medial displacement calcaneal osteotomy should be 7 to 15 mm of medialization of the tuberosity. The typical range when performing an Evans lateral column lengthening should be 5 to 10 mm of a laterally based wedge in the anterior calcaneus. The typical range when performing a plantarflexion opening wedge osteotomy of the medial cuneiform (Cotton) osteotomy should be 5 to 10 mm of a dorsal wedge., Level of Evidence: Level V, consensus, expert opinion.

Recommendation: The historical nomenclature for the adult acquired flatfoot deformity (AAFD) is confusing, at times called posterior tibial tendon dysfunction (PTTD), the adult flexible flatfoot deformity, posterior tibial tendon rupture, peritalar instability and peritalar subluxation (PTS), and progressive talipes equinovalgus. Many but not all of these deformities are associated with a rupture of the posterior tibial tendon (PTT), and some of these are associated with deformities either primarily or secondarily in the midfoot or ankle. There is similar inconsistency with the use of classification schemata for these deformities, and from the first introduced by Johnson and Strom (1989), and then modified by Myerson (1997), there have been many attempts to provide a more comprehensive classification system. However, although these newer more complete classification systems have addressed some of the anatomic variations of deformities encountered, none of the above have ever been validated. The proposed system better incorporates the most recent data and understanding of the condition and better allows for standardization of reporting. In light of this information, the consensus group proposes the adoption of the nomenclature "Progressive Collapsing Foot Deformity" (PCFD) and a new classification system aiming at summarizing recent data published on the subject and to standardize data reporting regarding this complex 3-dimensional deformity., Level of Evidence: Level V, consensus, expert opinion., Consensus Statements Voted: CONSENSUS STATEMENT ONE: We will rename the condition to Progressive Collapsing Foot Deformity (PCFD), a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot varus.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus) CONSENSUS STATEMENT TWO: Our current classification systems are incomplete or outdated.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus) CONSENSUS STATEMENT THREE: MRI findings should be part of a new classification system.Delegate vote: agree, 33% (3/9); disagree, 67% (6/9); abstain, 0%.(Weak negative consensus) CONSENSUS STATEMENT FOUR: Weightbearing CT (WBCT) findings should be part of a new classification system.Delegate vote: agree, 56% (5/9); disagree, 44% (4/9); abstain, 0%.(Weak consensus) CONSENSUS STATEMENT FIVE: A new classification system is proposed and should be used to stage the deformity clinically and to define treatment.Delegate vote: agree, 89% (8/9); abstain, 11% (1/9).(Strong consensus).

Recommendation: Progressive collapsing foot deformity (PCFD) is a complex 3D deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot supination. Although a medial displacement calcaneal osteotomy can correct heel valgus, it has far less ability to correct forefoot abduction. More severe forefoot abduction, most frequently measured preoperatively by assessing talonavicular coverage on an anteroposterior (AP) weightbearing conventional radiographic view of the foot, can be more effectively corrected with a lateral column lengthening procedure than by other osteotomies in the foot. Care must be taken intraoperatively to not overcorrect the deformity by restricting passive eversion of the subtalar joint or causing adduction at the talonavicular joint on simulated AP weightbearing fluoroscopic imaging. Overcorrection can lead to lateral column overload with persistent lateral midfoot pain. The typical amount of lengthening of the lateral column is between 5 and 10 mm., Level of Evidence: Level V, consensus, expert opinion., Consensus Statement One: Lateral column lengthening (LCL) procedure is recommended when the amount of talonavicular joint uncoverage is above 40%. The amount of lengthening needed in the lateral column should be judged intraoperatively by the amount of correction of the uncoverage and by adequate residual passive eversion range of motion of the subtalar joint.Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); abstain, 11% (1/9).(Strong consensus)., Consensus Statement Two: When titrating the amount of correction of abduction deformity intraoperatively, the presence of adduction at the talonavicular joint on simulated weightbearing fluoroscopic imaging is an important sign of hypercorrection and higher risk for lateral column overload.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)., Consensus Statement Three: The typical range for performing a lateral column lengthening is between 5 and 10 mm to achieve an adequate amount of talonavicular coverage.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus).

Recommendation: In the treatment of progressive collapsing foot deformity (PCFD), the combination of bone shape, soft tissue failure, and host factors create a complex algorithm that may confound choices for operative treatment. Realignment and balancing are primary goals. There was consensus that preservation of joint motion is preferred when possible. This choice needs to be balanced with the need for performing joint-sacrificing procedures such as fusions to obtain and maintain correction. In addition, a patient's age and health status such as body mass index is important to consider. Although preservation of motion is important, it is secondary to a stable and properly aligned foot., Level of Evidence: Level V, consensus, expert opinion.

Recommendation: There is evidence that the use of WEIGHTBEARING imaging aids in the assessment of progressive collapsing foot deformity (PCFD). The following WEIGHTBEARING conventional radiographs (CRs) are necessary in the assessment of PCFD patients: anteroposterior (AP) foot, AP or mortise ankle, and lateral foot. If available, a hindfoot alignment view is strongly recommended. If available, WEIGHTBEARING computed tomography (CT) is strongly recommended for surgical planning. When WEIGHTBEARING CT is obtained, important findings to be assessed are sinus tarsi impingement, subfibular impingement, increased valgus inclination of the posterior facet of the subtalar joint, and subluxation of the subtalar joint at the posterior and/or middle facet., Level of Evidence: Level V, consensus, expert opinion.

Recommendation: Peritalar subluxation represents an important hindfoot component of progressive collapsing foot deformity, which can be associated with a breakdown of the medial longitudinal arch. It results in a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and pronation. Loss of peritalar stability allows the talus to rotate and translate on the calcaneal and navicular bone surfaces, typically moving medially and anteriorly, which may result in sinus tarsi and subfibular impingement. The onset of degenerative disease can manifest with stiffening of the subtalar (ST) joint and subsequent fixed and possibly arthritic deformity. While ST joint fusion may permit repositioning and stabilization of the talus on top of the calcaneus, it may not fully correct forefoot abduction and it does not correct forefoot varus. Such varus may be addressed by a talonavicular (TN) fusion or a plantar flexion osteotomy of the first ray, but, if too pronounced, it may be more effectively corrected with a naviculocuneiform (NC) fusion. The NC joint has a curvature in the sagittal plane. Thus, preserving the shape of the joint is the key to permitting plantarflexion correction by rotating the midfoot along the debrided surfaces and to fix it. Intraoperatively, care must be also taken to not overcorrect the talocalcaneal angle in the horizontal plane during the ST fusion (eg, to exceed the external rotation of the talus and inadvertently put the midfoot in a supinated position). Such overcorrection can lead to lateral column overload with persistent lateral midfoot pain and discomfort. A contraindication for an isolated ST fusion may be a rupture of posterior tibial tendon because of the resultant loss of the internal rotation force at the TN joint. In these cases, a flexor digitorum longus tendon transfer is added to the procedure., Level of Evidence: Level V, consensus, expert opinion.

Recommendation: There is evidence that the medial displacement calcaneal osteotomy (MDCO) can be effective in treating the progressive collapsing foot deformity (PCFD). This juxta-articular osteotomy of the tuberosity shifts the mechanical axis of the calcaneus from a more lateral position to a more medial position, which provides mechanical advantage in the reconstruction for this condition. This also shifts the action of the Achilles tendon medially, which minimizes the everting deforming effect and improves the inversion forces. When isolated hindfoot valgus exists with adequate talonavicular joint coverage (less than 35%-40% uncoverage) and a lack of significant forefoot supination, varus, or abduction, we recommend performing this osteotomy as an isolated bony procedure, with or without additional soft tissue procedures. The clinical goal of the hindfoot valgus correction is to achieve a clinically neutral heel, as defined by a vertical axis from the heel up the longitudinal axis of the Achilles tendon and distal aspect of the leg. The typical range when performing a MDCO, while considering the location and rotation of the osteotomy, is 7 to 15 mm of correction., Level of Evidence: Level V, consensus, expert opinion.

Background: Lesser toe metatarsophalangeal (MTP) joint pathology presents a challenge for surgical treatment. At our institution, arthroplasty using a polyvinyl alcohol (PVA) hydrogel implant has been utilized in the second and third MTP joints for advanced arthritis, failed management of Freiberg's infraction, and osteochondral defects. We present a case series describing the clinical outcomes of 13 patients following PVA implantation of the second or third MTP., Methods: We retrospectively identified 13 patients (14 joints) who underwent PVA hydrogel implantation of the second ( n = 12) or third ( n = 2) metatarsal between 2017 and 2019. The average age was 49 (range, 20-67) years, with 100% females. Patient-Reported Outcomes Measurement Information System (PROMIS) scores were collected preoperatively and at an average of 21.1 (range, 8.3-29.2) months postoperatively. Clinical outcomes were also evaluated. The average time to clinical follow-up was 24.7 (range, 7-35.8) months., Results: On average, patients demonstrated pre- to postoperative improvement in all PROMIS domains, with significant improvements in Pain Intensity ( P = .01) and Pain Interference ( P = .01). Five postoperative complications were observed: 1 case of persistent avascular necrosis, 1 revision with implant removal and bone grafting, 1 periprosthetic fracture, and 2 recurrences of pain requiring ultrasound-guided injection., Conclusion: This study represents the largest case series to date evaluating the use of PVA implant in the surgical correction of lesser toe MTP joint pathology. While the PVA implant presents a viable option in the setting of advanced arthritis, Freiberg's infraction, and certain osteochondral defects, it is not without complications. The specific indications for use of the PVA implant should be carefully considered., Level of Evidence: Level IV, case series.

Background: Operative correction of flatfoot deformity has been well studied in the older population. There is a subset of younger patients without congenital foot deformity that also develop a collapsing flatfoot. However, assessment of outcomes across age groups is limited, especially in the young demographic. The purpose of our study was to compare operative outcomes of flatfoot reconstruction between these 2 age groups., Methods: Seventy-six feet (41 left, 35 right) in 71 patients who underwent flexible flatfoot reconstruction were divided into 2 groups based on age: ≤30 years (n = 22) and >30 years (n = 54). Exclusion criteria included congenital causes of flatfoot (tarsal coalition, vertical talus, overcorrected clubfoot). Average age was 20.8 years (range, 14-30) and 55.4 years (range, 35-74) in the younger and older cohorts, respectively. Preoperative and minimum 2-year postoperative Patient-Reported Outcomes Measurement Information Systems (PROMIS) scores were compared. Five radiographic parameters were assessed pre- and postoperatively: talonavicular coverage angle, lateral talo-first metatarsal angle, lateral talocalcaneal angle, calcaneal pitch, and hindfoot moment arm. Procedures performed and incidence of minor (removal of symptomatic hardware) and major (revision) reoperations were compared., Results: Younger patients were less likely to undergo flexor digitorum longus transfer, first tarsometatarsal fusion, spring ligament repair, and posterior tibial tendon repair (all P < .05). Both younger and older cohorts demonstrated significant improvement in multiple PROMIS domains at an average follow-up of 30.6 (range, 24-44) and 26.8 (range, 24-45) months, respectively ( P = .07). Younger patients demonstrated significantly higher pre- and postoperative Physical Function (mean difference postoperatively, 4.6; 95% confidence interval, 1.5-7.8; P = .03). There were no differences in radiographic parameters postoperatively. There were 8 (36.4%) reoperations (all minor) in the younger group, and 21 (38.9%) reoperations (6 major, 15 minor) in the older group ( P = .84)., Conclusion: Our data suggest that age may play a role in clinical outcomes, procedures indicated, and subsequent corrective reoperations. Younger patients maintained greater physical function with comparable radiographic correction, with less frequent indication for tendon transfers, arthrodesis, and additional corrective surgeries., Level of Evidence: Level III, retrospective comparative study., Competing Interests: 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. ICMJE forms for all authors are available online., (© The Author(s) 2020.)

Background: Severe adult-acquired flatfoot deformity (AAFD) is often associated with painful medial column collapse at the naviculocuneiform (NC) joint. However, many surgeons surgically correct the deformity without directly addressing this joint. The purpose of this study was to examine the role of first-tarsometatarsal (TMT) fusion combined with subtalar fusion in correcting deformity at the NC joint., Methods: We retrospectively analyzed 40 patients (41 feet) who underwent first-TMT and subtalar (ST) fusion as part of a flatfoot reconstructive procedure. We assessed 6 radiographic parameters both preoperatively and at a minimum of 6 months postoperatively, including talonavicular (TN) coverage angle, lateral talo-first metatarsal angle, lateral talocalcaneal angle, calcaneal pitch, hindfoot moment arm, and a newly defined navicular-cuneiform incongruency angle (NCIA). Patient-Reported Outcomes Measurement Information System (PROMIS) clinical outcomes were assessed preoperatively and at a minimum 1-year follow-up., Results: The NCIA demonstrated excellent interobserver reliability, with no significant change between pre- and postoperative measurements. All other radiographic parameters, except calcaneal pitch, demonstrated statistically significant improvement postoperatively ( P < .01). Overall, patients had statistically significant improvement in all PROMIS domains ( P < .01), except for depression. Worsening NC deformity was not associated with worse patient-reported outcomes., Conclusions: Our data suggest that when addressing painful collapse of the medial arch in patients with AAFD, fusion of the first-TMT joint in combination with other procedures leads to acceptable radiographic and clinical outcomes. There was no change in deformity at the NC joint in our patient cohort at short-term follow-up, and patients achieved significant improvement in multiple PROMIS domains. Although TMT fusion had no effect on NC deformity, residual or worsening NC deformity did not significantly affect clinical outcomes. In addition, the NCIA was found to be a reliable radiographic parameter to assess NC deformity in the presence of talonavicular and/or first-TMT fusion., Level of Evidence: Level III, retrospective comparative study., Competing Interests: 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. ICMJE forms for all authors are available online., (© The Author(s) 2020.)

Background: Semiautomatic 3-dimensional (3D) biometric weightbearing computed tomography (WBCT) tools have been shown to adequately demonstrate the relationship between the center of the ankle joint and the tripod of the foot. The measurement of the foot and ankle offset (FAO) represents an optimized biomechanical assessment of foot alignment. The objective of this study was to evaluate the correlation between FAO and traditional adult acquired flatfoot deformity (AAFD) markers, measured in different planes. We hypothesized that the FAO would significantly correlate with other radiographic markers of pronounced AAFD., Methods: In this retrospective comparative study, we included 113 patients with stage II AAFD, 43 men and 70 women, mean age of 53.5 (range, 20-86) years. 3D coordinates (x, y, and z planes) of the foot tripod (most plantar voxel of the first and fifth metatarsal heads, and calcaneal tuberosity) and the center of the ankle joint (most proximal and central voxel of the talar dome) were assessed by 2 blinded and independent fellowship-trained orthopedic foot and ankle surgeons. The FAO was automatically calculated using the 3D coordinates by dedicated software. Multiple WBCT parameters related to the severity of the deformity in the coronal, sagittal, and transverse planes were manually measured., Results: We found overall good to excellent intra- (range, 0.75-0.99) and interobserver (range, 0.73-0.99) reliability for manual AAFD measurements. FAO semiautomatic measurements demonstrated excellent intra- (0.99) and interobserver (0.99) reliabilities. Hindfoot moment arm (HMA) ( P < .00001), subtalar horizontal angle ( P < .00001), talonavicular coverage angle ( P = .00004), and forefoot arch angle ( P = .0001) were the only variables found to significantly influence and correlate with FAO measurements, with an R 2 value of 0.79. An HMA value of 19.8 mm was found to be a strong threshold predictor of increased values of FAO, with mean values of FAO of 6.5 when the HMA was lower than 19.8 mm and 14.6 when the HMA was equal to or higher than 19.8 mm., Conclusion: We found that 3D WBCT semiautomatic measurements of FAO significantly correlated with some traditional markers of pronounced AAFD. Measurements of FAO were also found to be slightly more reliable than the manual measurements. The FAO offers a simple and more complete biomechanical and multiplanar assessment of the AAFD, representing in a single measurement the 3D components of the deformity., Level of Evidence: Level III, retrospective comparative study.