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Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: The osseous structure of the foot has been described as an arch-like triangular structure or truss where the plantar fascia (PF) functions as the tensile element, maintaining the overall length of the arch. The importance of the PF in maintaining the arch has likely been underestimated because only minor abnormalities in its structure are seen on MRI studies in patients with flatfoot deformity. However, the importance of a ligament in preventing deformity may not be correlated with its attenuation seen on MRI. We hypothesized that the degenerative elongation of the plantar fascia would be a necessary precursor of arch collapse. The goal of this study was to evaluate the role of the plantar fascia in arch stability in flatfoot deformity. Methods: We used a validated finite element model of the foot reconstructed from CT scan of a female cadaveric foot weighing 60 kg. The model included 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The flatfoot model was created by simulated transection of the ligaments and unloading of the posterior tibial tendon. The model was used to assess the impact of isolated PF failure on the development of flatfoot deformity, evaluate the capability of the PF when reconstructed to restore foot alignment, and determine the amount of progressive strain that constitutes failure for each ligament. Foot alignment angles were used to evaluate the foot alignment. For comparison, the angles were also evaluated for other ligament tears. The impact of PF failure on force changes in the remaining ligaments was also investigated by quantifying ligament force changes during simulated PF cutting in the foot model. Results: When compared to the intact and flatfoot models, we found that the individual release of the PF cannot cause deformity (Figure 1). However, it significantly increased the force in the long (142%) and short plantar (156%), deltoid (45%), and spring ligaments (60%), potentially putting the foot at risk of arch instability over time. Moreover, we found that the PF was the structure most able to restore the arch (Figure 1a). The PF was also found to play a secondary role in reducing hindfoot valgus and forefoot abduction deformities (Figures 1b,1c). Moreover, to produce deformity, a considerable amount of attenuation in the spring (strain= 41%) and interosseous talocalcaneal ligament (strain= 27%), but only a small amount in the plantar fascia (strain= 10%) was needed. Conclusion: In comparing normal to flatfoot models of the foot, we found that isolated PF release did not cause arch collapse, but that arch collapse could not occur without elongation of the PF. While the progressive strain in the PF needed to enable arch collapse was small, the PF is a very long ligament, thus even small strain within the PF corresponds to substantial change in overall length of the arch. Chronic degeneration of the PF leading to plantar fasciitis may be an early sign of impending flatfoot deformity.

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Triceps surae muscle force is transferred through the Achilles tendon to the calcaneus and from the calcaneus to the plantar fascia and then to the metatarsal heads and the toes which exert force on the ground. Achilles tendon ruptures occur in tendons that have reached a critical point of intrasubstance degeneration. The Achilles tendon almost always heals but frequently lengthens during the healing process, leading to an alteration in the triceps surae force production profile. We hypothesized that Achilles tendon overlengthening has implications not only for force generation but likely has many other impacts throughout the foot. The goal of this work was to evaluate the effect of a lengthened Achilles tendon following tendon repair on the kinetics of the foot. Methods: A validated finite element model of the foot was used to compare foot biomechanics between the foot with a functional and non-functional Achilles tendon. The model of the foot constructed from CT scan images of a female cadaveric foot weighing 60 kg included all 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The model was loaded with 0.5 body weight applied at the center of mass and 0.25 body weight applied to the Achilles tendon simulating quiet stance. The tendon forces were applied using force vectors in the direction of their lines of action. The foot with a non-functional Achilles tendon was created by unloading the Achilles tendon since triceps surae muscle shortening due to tendon lengthening significantly decreases force production. The force transmitted through the joints, force in the ligaments, and plantar pressure were determined for both the foot with a functional and non-functional Achilles tendon. Results: We found that the force transmitted through all the joints decreased when the Achilles tendon force was removed (Figure 1a). In addition, removing the Achilles tendon decreased the force within the plantar fascia, long and short plantar ligaments, and deep deltoid ligament, while it increased the force within the spring and superficial deltoid ligaments (Figure 1b). The plantar fascia experienced the greatest reduction in ligament force after unloading of the Achilles tendon (from 93 N to 26 N). Moreover, the maximum plantar pressure in the heel fat pad increased from 164 kPa to 231 kPa when the Achilles tendon was removed. Conclusion: The varying changes in the force in the ligaments and joints due to Achilles lengthening suggest that Achilles tendon rupture with sequent healing with overlengthening can alter the force distribution throughout the entire foot. A major implication of this work is that in treating Achilles ruptures, an extended period of protection with heel wedges beyond the customary six weeks may be needed to prevent over lengthening of the Achilles. Moreover, this study supports the efficiency of surgical lengthening of the Achilles in the treatment of diabetic forefoot foot ulcers by shifting the plantar pressure towards the calcaneus.

Ankle fractures are common musculoskeletal injuries that may result in tibiotalar joint dislocations. Ankle fracture-dislocations occur via similar mechanisms as ankle fractures, although the persistence or magnitude of the deforming force is sufficient to disrupt any remaining bony or soft-tissue stability. Ankle fracture-dislocations likely represent distinct clinical entities, as the pathology, management, and patient outcomes following these injuries differ from those seen in more common ankle fractures without dislocation. Ankle fracture-dislocations have higher rates of concomitant injury including open fractures, chondral lesions, and intra-articular loose bodies. Long-term outcomes in ankle fracture-dislocations are worse than ankle fractures without dislocation. Higher rates of posttraumatic osteoarthritis and chronic pain have also been reported. In this review, we discuss the current literature regarding the history, management, and outcomes of ankle-fracture dislocations and highlight the need for future study.

Anatomic lateral ankle ligament reconstruction using free tendon graft with osseous tunnels has become a popular technique for revision reconstruction of the lateral ankle ligaments. With the procedure’s burgeoning popularity, an accompanying increase in postoperative complications is likely to occur. We report on one such complication: traumatic distal fibula fracture through the transosseous tunnels.

Category: Hindfoot; Ankle; Ankle Arthritis Introduction/Purpose: Patients with longstanding progressive collapsing foot deformity (PCFD) often develop osteoarthritis of the peritalar (tibiotalar, subtalar, and talonavicular) joints, which can be symptomatic or can lead to fixed deformities that further complicate the treatment of other sequalae of the deformity (Mann, 1992). Degeneration and subsequent tearing of the arch supporting ligaments leads to altered joint contact mechanics which is a likely causative factor in the development of arthrosis (Hauser and Dolan, 2011). However, the initial effect of ligament tears on changes in joint contact mechanics in the collapsing foot has not been well characterized. The goal of this work was to compare the joint contact mechanics between the neutrally aligned and the flexible flatfoot (collapsed foot). Methods: A validated finite element model of the foot (Malakoutikhah et al., 2022a) was used to compare joint contact pressures between the normally aligned and the collapsed foot. The model of the foot constructed from CT scan images of a female cadaveric foot weighing 60 kg included all 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The model was loaded with 0.5 body weight applied at the center of mass and 0.25 body weight applied to the Achilles tendon simulating quiet stance. The collapsed foot model was created by simulated transection of the plantar fascia, long plantar, short plantar, deltoid, and spring ligaments and unloading of the posterior tibial tendon (Malakoutikhah et al., 2022b). The joint contact pressure maps were determined for both the neutrally aligned and collapsed foot models. The average and peak contact pressures were compared. Results: The peak contact pressures were increased in the tibiotalar and subtalar joints, but paradoxically were decreased in the talonavicular joint in the collapsed as compared to the neutrally aligned foot (Figure 1). The center of pressure was markedly different in all three joints between the neutral and collapsed foot conditions. Specifically, collapsing the foot caused two centers of the talonavicular joint peak pressure to shift towards the central region of the navicular bone, which were evenly distributed in the lateral and medial regions in the neutrally aligned foot. In the subtalar joint, the peak pressure that was uniformly distributed in the lateral and medial regions of the posterior facet in the neutrally aligned foot shifted towards the lateral region in the collapsed foot. Similarly, the peak contact pressure across the tibiotalar joint moved from the center to the lateral region when the foot collapsed. Conclusion: Degenerative tearing of the arch supporting ligaments in PCFD leads to an increase and laterization of the contact pressure in the tibiotalar and subtalar joints with a decrease of the pressure in the talonavicular joint. The paradoxical unloading of the talonavicular joint may be a result of the inability of the malaligned medial column to transmit force from the hindfoot to the forefoot. One implication of this work is that future treatments of PCFD might be directed towards normalizing contact pressure within the peritalar joints to prevent the progression of disease and the development of arthrosis.

Category: Ankle Introduction/Purpose: Suspected peroneal tendinopathy, tears, and subluxation are often confirmed using magnetic resonance imaging (MRI) or diagnostic ultrasound (US). The choice between these two imaging modalities is commonly based on surgeon preference as the accuracy of these tests for the diagnosis of peroneal tendinopathy, tears, and subluxation is not known. The purpose of this study was to compare MRI and US to the intraoperative findings in patients who underwent surgery for the treatment of suspected peroneal tendinopathy, tears, and subluxations to determine the diagnostic accuracy of each imaging modality. Methods: The operative records and diagnostic images for 21 patients who underwent surgery for suspected peroneal tendinopathy, tears, or subluxation were retrospectively reviewed. Two fellowship trained musculoskeletal radiologists conducted a systematic blinded review of the stored MRI and US images. The results of this review were compared with the intraoperative findings to yield the sensitivity and specificity for each imaging modality. Results: For the diagnosis of peroneus brevis tears, both MRI and ultrasound were equally good at detecting tears. In the diagnosis of peroneus brevis tears, MRI was marginally better with a sensitivity and specificity of 100% versus ultrasound, which had a sensitivity of 90% and specificity of 100%. In the diagnosis of peroneal subluxation, ultrasound had a sensitivity of 100% and a specificity of 100% compared to MRI, which had a sensitivity of 33% and specificity of 100%. Conclusion: In comparing MRI and US to intraoperative findings for the diagnosis of peroneal tendinosis, tears and subluxation, we found ultrasound to be more effective at diagnosing peroneal tendinopathy and subluxation, while MRI was found to be slightly more accurate in the diagnosis of peroneus brevis tendon tears. Both MRI and ultrasound were effective for the diagnosis of peroneus longus tears.

Category: Other; Ankle; Hindfoot; Midfoot/Forefoot Introduction/Purpose: As digital healthcare systems advance, patient reported outcomes (PRO) platforms offer an effective strategy for clinicians to evaluate patient relevant treatment outcomes. Initiated by AOFAS in 2018, the Orthopaedic Foot and Ankle Outcomes Research (OFAR) Network was a multi-center surgical outcomes registry platform established to collect, aggregate, and report PRO data. OFAR included surgical information, patient demographics, and PRO instruments developed by the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS). Due to high costs and competing technologies, OFAR data collection ended in 2020. Although OFAR did not achieve widespread and sustained use, a large number of patients were enrolled over the 2-year period. We hypothesized that each aggregated PRO metric improved at all post-operative time points compared to preoperative values. Methods: From 2018-2020, four sites and 10 orthopedic surgeons were approved and able to contribute patient data to the OFAR database. Enrolled patients completed a pre-operative survey and then post-operative surveys at 3-months, 6-months, and 12-months. Five PROMIS metrics were collected at each survey point, including Physical Function CAT (PF), Pain Intensity Short Form (PI), Pain Interference CAT, Global Health Short Form and Depression CAT. Descriptive statistics were used to summarize the demographics and clinical characteristics of all individuals. Linear mixed models were used to test for differences in patient reported outcomes (PROs) across the study visits. The unstructured covariance structure was used to account for the repeated measures. After the OFAR closed to enrollment, all investigators of the OFAR consortium, including those who were not able to participate as a site, were surveyed to investigate the barriers they faced when launching OFAR at their site. Results: The final OFAR database includes 1,675 procedures performed at four institutions, with 1,126 having complete data for analysis. Ankle impingement (12%), ankle fracture/syndesmosis (11%), ankle arthritis (10%), and hallux valgus (9%) were the most common conditions among 28 unique conditions. The cumulative incidence of post-operative complications was 6.2% and the re- operation rate was 1.5%. Relative to the pre-operative visit, there was significant improvement in all metrics across post-operative time points (Table 1). The majority of OFAR consortium member sites (15 of 19) were unable to enroll patients in OFAR. The most common barriers noted included resistance from institutional EMR/IT or compliance teams, and institutional requirements to collect PROs through another platform. The majority of OFAR members (55%) indicated they would participate in a future low-cost, low-effort multi-center outcomes database. Conclusion: The OFAR database successfully collected patient outcomes data from multiple institutions. The resulting database also provided a comprehensive resource to answer targeted clinical questions about outcome predictors for common interventions. Barriers to participation in a multi-center registry more frequently emanated from the technologic or compliance constraints of hospital systems rather than individual providers. Increasing demand for PROs in practice, combined with the evolving technical landscape of greater automation and EHR interoperability will lead to more sustainable, affordable, and collaborative outcomes platforms. Institutional EMR and compliance barriers remain an important factor in advancing these important initiatives.

Category: Ankle; Midfoot/Forefoot; Other Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a degenerative disorder of ligaments and tendons that encompasses a wide range of deformities, including arch height loss, hindfoot valgus, and forefoot abduction. The posterior tibial tendon (PTT) is the main active stabilizer of the arch. We hypothesize that it may become injured secondarily as it attempts to maintain foot stability when the ligaments, passive stabilizers, are attenuated. Several cadaveric studies have been conducted on the role of the PTT in PCFD, but the ability of the PTT to compensate for the loss of the ligamentous stabilizers has not been clearly characterized. We developed a high-fidelity finite element model of the foot to determine the PTT's ability to maintain foot stability when the principle ligamentous stabilizers are attenuated. Methods: The encapsulating soft tissue (EST), cartilage, and cortical and trabecular bones were reconstructed in Mimics from CT scan images of a female cadaveric foot weighing 60 kg. Tension-only spring elements were used to reflect all the ligaments in ANSYS. Bodyweight and tendon forces were applied using force vectors in the direction of their lines of action. The proximal tibia was fixed only in the vertical direction, allowing it to translate and rotate in all other degrees of freedom. Nonlinear frictional contacts were used between the EST and the ground, and between the cartilages. The flatfoot was simulated by removing all of the ligaments. We measured the foot alignment angles for the flatfoot and the foot with ruptured spring/deltoid ligament, while we gradually increased the force within the PTT. The measured angles were then compared to the intact foot to evaluate the ability of the PTT to restore foot alignment. Results: The models were validated by comparing the Meary's (MA), calcaneal pitch (CPA), hindfoot alignment (HAA), and talonavicular coverage angles (TCA) to clinically-derived values. In the flatfoot, an increase of the PTT force to approximately 700% of normal ('7 ×25.71 N=180 N') led to a nearly complete restoration of foot alignment (Fig. 1). The angles associated with arch height (MA/CPA) were restored to a lesser extent than those associated with hindfoot and forefoot alignment (HAA/TCA). For the foot with ruptured deltoid ligament, increasing force within the PTT by 500% led to a restoration of near normal hindfoot alignment (Fig. 1c). For the foot with ruptured spring ligament, the forefoot abduction was completely compensated only when the PTT force was increased to 1100% of normal (Fig. 1d). Conclusion: Almost seven times the normal PTT force is required to restore the foot to neutral alignment. Augmentation of PTT force to this extent is unrealistic. However, a lesser increase in PTT force provides partial alignment compensation. Furthermore, the restoration achieved by overloading the PTT primarily impacts the alignment of the hindfoot and forefoot rather than the arch. Because the PTT can partially restore foot alignment, it may become secondarily injured when the ligaments are torn. Strengthening of the PTT through therapeutic exercise can improve its ability to restore foot alignment and should be a cornerstone of non-operative treatment of PCFD.

Background: Nonunion following hindfoot arthrodesis may be caused by failure to maintain compression at the arthrodesis site. The ability of lag screws, commonly used in arthrodesis, to maintain compression in hindfoot bones has not been well characterized. The aim of this work was to quantify the stress relaxation response of hindfoot bone with initial and repeated compression with a lag screw. Methods: Ten sets of 25-mm-diameter bone cylinders were cut from the talus and calcaneus in fresh-thawed cadaveric feet. A load cell was compressed between cylinders with an 8.0-mm partially threaded cannulated lag screw simulating arthrodesis. For 7 sets, screws were tightened by 3 quarter-turns, rested for 3 minutes, retightened 1 quarter-turn, and rested for 30 minutes. Three sets served as controls in which screws were not retightened. Results: Maximum compression after initial screw tightening and retightening averaged 275 and 337 N ( P = .07), respectively. Compression 3 minutes after initial screw tightening and retightening averaged 199 and 278 N ( P = .027), respectively. The compression recorded 3 minutes after screw retightening was an average of 40% higher than that recorded 3 minutes after initial tightening. The average compression 30 minutes after screw retightening was 255 N, a compression loss of 25% from the average maximum compression after retightening. Eighty percent of this compression loss happened in an average of 5.5 minutes. Conclusion: Hindfoot bones exhibit compression loss over time during simulated arthrodesis. Compression maintenance in bone is improved with screw retightening. Further work is needed to understand the mechanism of action and determine optimum time for recompression. Clinical Relevance: Retightening lag screws before wound closure may improve compression at the arthrodesis site and thereby decrease the chance of nonunion. Level of Evidence: N/A, laboratory experiment.

Category: Basic Sciences/Biologics; Ankle; Hindfoot; Trauma Introduction/Purpose: Decreased tibiotalar joint contact area (CA) and increased peak pressure (PP) following rotational ankle fractures may predispose the development of post-traumatic osteoarthritis. Previous studies have highlighted the effects of lateral talar translation on tibiotalar joint congruity. However, debate remains regarding surgical indications in minimally displaced (< 2mm of clear space widening), but potentially malrotated ankle fractures. Malrotation of the talus and fibula are poorly visualized on plain radiographs, thus their impact on ankle joint contact mechanics has not been determined. The aim of this project is to understand the effects of fibular malrotation on tibiotalar joint CA and PP distributions using an axially loaded cadaveric model. We hypothesized that fibular malrotation would result in decreased contact area and increased peak pressures within the tibiotalar joint. Methods: Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 147 N load via the Achillies tendon at mid-stance position, 15o dorsiflexion and 15o plantarflexion. The samples were first tested in the native condition, a Weber B ankle fracture was simulated and then re-tested in an anatomically fixed state, and a malrotated state. Malrotation was achieved by externally rotating the talus and shortening the fibula along the fracture by the maximal amount that would allow bony apposition along the fracture line (usually 5-10mm). Results: In the six ankles tested thus far (Figure 1), we have observed small but statistically insignificant (P>0.05) increases in tibiotalar CA at all stance phases following malreduction. Significant (p>0.05) increases in tibiotalar PP were seen mid-stance following a simulated Weber B fracture, and these changes were shown to be greatest in the malreduced state versus the anatomically fixed state (7.21 MPa vs. 6.35 MPa respectively, p = 0.004). Interestingly, similar (p=0.84) decreases tibiotalar PP were shown during plantarflexion following a simulated Weber B fracture fixed in both the anatomically fixed and malreduced state. Conclusion: Our preliminary data supports the notion that significant changes in tibiotalar PP occur following ankle fractures even in an anatomically fixed state. Increases in tibiotalar PP seem to be further amplified following malreduction at specific stance phases. Further data collection is needed to validate these findings, and to determine the role of malrotation as a potential surgical indication for minimally laterally displaced ankle fractures.

Category: Diabetes; Ankle; Diabetes; Hindfoot Introduction/Purpose: Charcot neuroarthropathy of the hindfoot (Brodsky type 2 and 3) can involve significant talar collapse / bone loss leading to hindfoot instability, the goal of treatment to create a stable plantigrade shoeable ulcer and infection free foot. This can often be achieved with tibiotalocalcaneal (TTC) arthrodesis but a plantigrade foot can be challenging in setting of significant talar bone loss. Structural allograft has been used in association with TTC fusions in a number of settings but not explored in the treatment of charcot hindfoot. The goal of this study was to examine the outcomes of structural allografting combined with TTC arthrodesis for the treatment of charcot hindfoot. Methods: Retrospective review of all patients treated at our institution with a Brodsky type 2 or 3 was performed over a five year period from 2014 - 2019. We identified twenty-two patients, 12 males and 10 females with a mean age of 57 years. All underwent surgery by the senior author, a fellowship trained foot and ankle orthopedic surgeon. Patients with infection were treated with antibiotics and a Taylor spatial frame prior to definitive stabilization. Non-infected patients were either placed in a total contact cast (TCC) if they were in active charcot or underwent primary charcot reconstruction. If after initial treatment patients had a plantigrade foot, they were placed in stiff soled rocker bottom shoe with custom accommodative insoles. Patients who did not have a plantigrade foot underwent TTC arthrodesis to achieve this. Femoral head allograft was used if excessive talar bone loss or collapse of the hindfoot was noted. Results: At final follow up 13 patients (59%) of the cohort achieved grade 1, an infection and ulcer free plantigrade foot that was able to fit in a shoe. 7 (32%) of patients achieved grade 2, a plantigrade foot in brace, and 2 (9%) achieved level 3 a plantigrade foot. No patients in this cohort underwent amputation. Average duration of treatment until final status was 18 months (minimum 2, maximum 37), number of interventions 3.9 (minimum 1, maximum 10). Of the twelve patients who required allograft, they averaged 4.25 interventions and average time of 17.6 months until final status. Of those who did not require allograft, they averaged 3.4 interventions with follow up of 11.9 months. Conclusion: Our data suggests that patients with Brodsky type 2 and 3 charcot arthropathy of the ankle and hindfoot even with infection can be successfully treated with staged treatment. This includes external fixation and infection management, followed by tibiotalocalcaneal intramedullary nail fixation with or without femoral head allograft to allow for a plantigrade foot and weight bearing in a stiff soled rocker bottom shoe. Further study is needed to determine long term outcomes and relapse rates.

Category: Hindfoot; Ankle; Ankle Arthritis Introduction/Purpose: Non-union and delayed union are common complications following hindfoot arthrodesis. The failure to obtain and maintain compression at the arthrodesis site may be a causative factor. Partially threaded cannulated ‘lag’ screws are commonly used for fixation in hindfoot arthrodesis; however, the ability of these screws to maintain compression in the hindfoot bones has not been well-characterized. The goals of this work were to: 1) quantify the stress relaxation response of hindfoot bones when compressed with a lag screw, particularly compression change upon screw retightening, and 2) compare the results to prior studies on stress relaxation in direct bone compression. Methods: 12 pairs of calcaneus, talus and tibia bone cylinders, 25mm in diameter, were cut with a keyhole saw from fresh thawed cadaveric feet. The bone cylinders were prepared for simulated arthrodesis by removing the cartilage and flattening the subchondral surface with an oscillating saw. A Futek LTH 300 donut load cell and two metal washers were sandwiched between the two bone cylinders. An 8.0mm partially threaded cannulated lag screw (Smith and Nephew) was placed from the posterior- inferior aspect of the calcaneus cylinder to the anterior-superior aspect of the talus cylinder to simulate subtalar arthrodesis, or from the superior aspect of the tibia cylinder to the inferior aspect of the talus cylinder. Compression was recorded continuously as the screws were tightened by three-quarters of a turn and left untouched for 3 minutes. Recording continued as the screws were retightened one quarter-turn and then left untouched for 30 additional minutes. Results: Both initial and subsequent compression with a lag screw demonstrated a stress relaxation pattern, with increased maximum compression and slowed decay upon retightening. Maximum compression after three quarter-turns and retightening averaged 284 N and 351 N, respectively (n=12; t=-2.55; p=0.0136). Time to decay to 80% of maximum compression after three quarter-turns and retightening averaged 34 and 528 (n=9; t=-2.59; p=0.0159) seconds, respectively, compared to 21 seconds for direct compression. Compression loss 30 minutes after retightening averaged 25.5% (SD=8.8%), compared to 34.3% for direct compression. Conclusion: The maximum compression attained following retightening was significantly greater than the maximum compression attained after initial tightening. The time required to reach 80% of maximum compression was significantly longer after subsequent compared to initial maximum compression. These findings suggest that screw retightening before surgical wound closure may slow compression loss, which could increase the likelihood of successful arthrodesis. Lag screw compression resulted in a lower percent compression loss and loss rate compared to direct compression, which was previously used to describe bone viscoelasticity.

Plantar fasciitis is the most common cause of chronic heel pain in adults, affecting both young active patients and older sedentary individuals. It results from repetitive stress to the plantar fascia at its origin on the medial tubercle of the calcaneus and is often associated with gastrocnemius tightness. The diagnosis can be made clinically with a focused history and physical examination; imaging is reserved for atypical presentations and those that do not respond to initial treatment. The most common presenting symptom is aching plantar heel pain, which is worst with first step in the morning or after periods of rest. Diagnosis is confirmed with point tenderness at the origin of the plantar fascia on the medial tubercle of the calcaneus. Initial treatment consists of activity modification, anti-inflammatory medication, gastrocnemius and plantar fascia stretching, and an in-shoe orthosis that lifts and cushions the heel. These nonoperative treatments lead to complete resolution of pain in 90% of patients but can take 3-6 months. Patients who remain symptomatic despite a 6-month trial of nonoperative therapy may be considered for minimally invasive treatment or surgery. Platelet-rich plasma injections and therapeutic ultrasound are among a number of minimally invasive treatments that stimulate the body’s healing response. Corticosteroid injections temporarily relieve pain, but may increase the risk of plantar fascia rupture and fat pad atrophy. Botulinum toxin injections relax the calf muscles, which decreases the stress in the plantar fascia. Operative treatments include gastrocnemius recession and medial head of gastrocnemius release, which decrease the stress on the plantar fascia and partial planter fasciotomy, which stimulates a healing response. Level of Evidence: Level V, expert opinion.

Category: Patient Reported Outcomes Introduction/Purpose: Collection and reporting of Patient Reported Outcomes (PROs) has become an integral part of healthcare and healthcare research. In an effort to facilitate AOFAS member participation in secure and efficient patient outcomes data collection, the Orthopaedic Foot and Ankle Outcomes Research (OFAR) Network, a national collaborative surgical outcomes registry, was established in 2018 by and for AOFAS member surgeons and their patients. OFAR aims to collect, aggregate, and report PRO data using the measurement instruments developed by the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS). We hypothesize that multiple sites from a variety of health systems can successfully enroll patients into a secure, web-based registry, and that foot and ankle procedures will significantly improve patient reported function and pain. Methods: Since December 2018, seven OFAR pilot sites have been enrolling patients, including three private and four academic practices. Each enrolled patient completed a pre-operative assessment as well as post-operative assessments at 3 time points. Five PROMIS metrics were collected, including Physical Function CAT (PF), Pain Intensity Short Form (PInSF), Pain Interference CAT (PInCAT), Global Health Short Form, and Depression CAT. Pathways, a secure web platform accessible by both patients and providers, was utilized for data collection and storage. The platform also includes a provider dashboard that collects diagnosis, treatment, implant and complication data. The aggregated data was analyzed using Python (v3.6) along with Pandas (v0.23.4). Results: As of December 2018, 877 patients have been enrolled in OFAR. Patients were enrolled from both academic (57%) and private practice (43%) sites. The three most frequently encountered conditions were: ankle impingement, ankle fractures and ankle arthritis. The largest pre- to postoperative changes were seen in the PF and PInCAT scores which significantly improved at 6 months and 12 months for nearly all condition groups (Figure 1). Many of these improvements averaged 20 points on the PROMIS t-score scale, which represents two standard deviations in the PROMIS scoring system, and restored PInCAT and PF to 50 or better, the US healthy population average. There was a trend toward improvement in depression scores for most conditions, with substantial improvement following fracture treatment. Conclusion: We were able to successfully onboard multiple pilot sites, including community private practices without dedicated research resources, to enroll patients in the OFAR platform. Aggregated data demonstrate a significant improvement in PROMIS scores for all conditions treated. The library of information collected is automated, extensive and comprehensive. By aggregating outcomes following treatment by orthopaedic foot and ankle surgeons across practice settings, the OFAR database empowers an unprecedented scrutiny of ‘real world’ patient outcomes and related factors. This facilitates an increasingly granular assessment of the impact of conditions and treatments, enabling patients and providers alike to share in the decision-making process.

Category: Ankle, Ankle Arthritis, Basic Sciences/Biologics, Hindfoot Introduction/Purpose: Hindfoot arthrodeses have a non-union rate as high as 40%. Compression at the arthrodesis site plays a key role in stimulating bone growth leading to successful fusion. The ability to obtain and maintain compression depends not only on the surgical technique and the hardware which develop the compressive force but also on the response of the bone to compression. Bone, like other musculoskeletal tissues, is viscoelastic meaning that it has properties of both fluids and solids. Because bone is viscoelastic, it experiences stress relaxation (decrease in compressive force over time). The rate and magnitude of such stress relaxation is unknown. Our primary objective was to quantify stress relaxation of the hindfoot bones when subjected to a fixed compression displacement as would be done during arthrodesis. Methods: 10 human cadaveric bone cylinders measuring 10 mm in both diameter and height were cut from the articular surfaces of the talus, calcaneus, and distal tibia using a disposable cylindrical osteochondral harvester (OATS, Arthrex inc, Naples, FL). Each bone cylinder sample included subchondral and trabecular bone, and articular cartilage was removed during preparation. Each sample was scanned with a micro-computed tomography (uCT) scanner (Biomedical Micro CT Scanner, Scanco Medical, Switzerland) to quantify bone volume/total volume ratio (BV/TV), trabecular thickness, trabecular separation, trabecular number, and connectivity density. Each specimen was submerged in a saline bath and compressed by 1 mm at a strain rate of 1mm/sec using a material testing machine (System 810, MTS Systems, Eden Prairie, MN), and load data was gathered by an Interface load cell. Displacement was held constant for 3 hours, after which each sample was removed from the test machine and immediately rescanned with the uCT scanner. Results: The ensemble load curve of the ten samples displayed uniform exponential decay. After the initial load was placed on the bone, a steep, negative load velocity was apparent. Rapid decay occurred within the first 3 minutes, after which the load plateaued, holding constant over the subsequent 3 hours of compression. The average peak load was 515.53 N (SD: 254.58 N). The average percent load loss was 65.77% over 30 minutes (SD: 20.95%). Discrete time periods (B1, B2, B3, B4) were established corresponding to 0-3 min, 3-10 min, 10-20 min, and 20-30 min, respectively. Time periods B1, B2, B3, and B4 demonstrated an average percent load loss per time period of 43.35% (SD: 10.09%), 13.80% (SD: 14.77%), 18.65% (SD: 24.97%) and 7.95% (SD: 13.37%), respectively. Conclusion: Our data suggest that a significant percentage of compressive load placed across a bone is lost within the first 3 minutes as compared to any subsequent time period. Moreover, approximately 65.77% of the compressive load is lost over the first 30 minutes. These data suggest that when performing arthrodesis with compressive hardware, the majority of the initially applied compressive load may dissipate over the first 3-30 minutes, which may contribute to nonunion. Thus, a re-tightening of screws after 5-30 minutes or the use of a continuous compressive device may help to maintain compression at the arthrodesis site throughout healing.

Level of Evidence: Level V, expert opinion.

Background: Intense therapeutic ultrasound (ITU) is an innovative ultrasound-based therapy where sound waves are concentrated into select musculoskeletal tissue. These focused waves generate thermal coagula at a controlled depth and space while preserving surrounding tissues. A multicenter study was conducted evaluating the efficiency, safety, and patient tolerance of ITU for the treatment of chronic plantar fasciitis (CPF) pain. Methods: Seventy-four CPF patients, having failed conservative and/or minimally invasive treatment, participated in the study. Randomized participants either received 2 ITU treatments or 2 sham ITU treatments in addition to standard-of-care therapy. Plantar fascia pain was assessed pretreatment and at 4, 8, 12, and 26 weeks after treatment. Diagnostic ultrasonographic images were analyzed to examine hypoechoic, perifascial lesions whose volumes were calculated until week 12. Function and patient satisfaction were measured using self-reported outcome measures. Results: The treated group reported significant average pain reduction (–26%, –33%, –43%) and hypoechoic lesion volume (–33%, –53%, –68%) at weeks 4, 8, and 12 compared to baseline. Although the control/sham group reported insignificant pain changes at the same time points (–5%, +8%, and +2%) and increased hypoechoic lesion volume (+15%, +28%, +58%). Treated patients reported a significant increase in daily living activities (+28%, +42%, +47%, +40%) compared to the sham/control group (+0.12%, +12%, +3%, +21%). Patient satisfaction remained more than 80% at weeks 8, 12, and 26 for all treatment groups. Conclusion: ITU is an effective pain relief treatment for CPF, which is refractory to either conservative measures or minimally invasive treatments. Level of Evidence: Level II.

Category: Ankle Introduction/Purpose: Increased tibiotalar peak pressure (PP) and decreased contact area (CA) following ankle fracture are associated with the development of post-traumatic osteoarthtritis. Lateral talar translation of just 1 mm has been shown to decrease CA by 42%. The impact of talar malalignment in other directions on ankle joint contact pressures (AJCP) are not well understood. The majority of research on AJCP has utilized cadaveric models in which body weight is simulated with an axial load applied through the tibia. This model does not account for Achilles tendon - which transmits the largest tendon force in the body during weight bearing. This study aimed to determine the effects of Achilles tendon loading on tibiotalar CA and PP in an axially loaded cadaver model at different ankle flexion angles. Methods: Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan KScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 350 N load via the Achilles tendon to simulate mid-stance conditions. Measurements were taken at neutral position, 15 degrees of dorsiflexion and 15 degrees of plantarflexion, with and without Achilles load. The effects of Achilles load and ankle flexion angle on CA and PP were analyzed using a 2x3 ANOVA. Bonferroni post-hoc adjustments were used for multiple comparisons. Level of statistical significance was set at p < 0.05. Results: ANOVA revealed significant main effects of ankle flexion on contact area and peak pressures (Table 1). Contact area was significantly lower for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion (p < 0.001). In addition, peak pressure was significantly higher for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion. ANOVA also indicated that contact area and peak pressure were significantly higher with Achilles load than without (p < 0.001). No interaction effects were found. Conclusion: The applied Achilles tendon load significantly altered tibiotalar PP in an axially loaded cadaver model. On the other hand, changes in CA with Achilles load were found to be minimal (~1.8%). We also found that the greatest PP and smallest CA occured during plantar flexion. This observation can be explained by a difference in width between the anterior and posterior talus. While the results of this study demonstrate the importance of Achilles tendon load on tibiotalar measurements, further studies investigating the effects of additional factors such as loading techniques are warranted to improve the physiological accuracy of cadaver models.

Ankle fractures are common musculoskeletal injuries that may result in tibiotalar joint dislocations. Ankle fracture-dislocations occur via similar mechanisms as ankle fractures, although the persistence or magnitude of the deforming force is sufficient to disrupt any remaining bony or soft-tissue stability. Ankle fracture-dislocations likely represent distinct clinical entities, as the pathology, management, and patient outcomes following these injuries differ from those seen in more common ankle fractures without dislocation. Ankle fracture-dislocations have higher rates of concomitant injury including open fractures, chondral lesions, and intra-articular loose bodies. Long-term outcomes in ankle fracture-dislocations are worse than ankle fractures without dislocation. Higher rates of posttraumatic osteoarthritis and chronic pain have also been reported. In this review, we discuss the current literature regarding the history, management, and outcomes of ankle-fracture dislocations and highlight the need for future study.

Anatomic lateral ankle ligament reconstruction using free tendon graft with osseous tunnels has become a popular technique for revision reconstruction of the lateral ankle ligaments. With the procedure’s burgeoning popularity, an accompanying increase in postoperative complications is likely to occur. We report on one such complication: traumatic distal fibula fracture through the transosseous tunnels.

Category: Sports Introduction/Purpose: Initial treatment of plantar fasciitis (PF), consisting of anti-inflammatories, stretching and in-shoe orthosis (heel pad, heel wedge, or arch support), leads to symptomatic resolution in over 90% of patients but takes 3-6 months. This study was conducted to test the effectiveness of a minimally invasive modality, intense therapeutic ultrasound (ITU), in accelerating the healing of chronic plantar fasciitis (PF). ITU uses high-frequency high-intensity focused ultrasound to create small thermal injury zones inside soft tissue without damage to surrounding structures. ITU has been shown to initiate a tissue repair cascade and promote collagen generation in dermal and musculoskeletal tissue and is FDA approved for use in non-surgical brow lifts [1,2]. The goal of this study was to determine if ITU when combined with standard therapy could speed the healing of chronic PF. Methods: 47 patients with chronic (greater than 3 months) heel pain due to PF were randomized to standard therapy (anti- inflammatory pills, stretching, and gel heel cups) plus ITU (“ITU”, n=33) or standard therapy plus sham ITU (“control”, n=14) groups. ITU treatments were administered at enrollment and two-weeks later using a custom 3.3 MHz therapeutic ultrasound system (Guided Therapy Systems, Mesa, AZ). Sham treatment utilized the same protocol but with the energy set to 0 Joules. Treatment effect was assessed at 2, 4, 6, and 12 weeks after the initiation of treatment using diagnostic ultrasound and patient reported outcomes (PROMIS physical function computer adaptive test, PROMIS global health, Foot Function Index pain subscale, and a non-validated heel pain specific questionnaire). Ultrasound images were analyzed to determine the size of lesions within the PF. Both the sonographer and the study coordinator administering the patient reported outcome instruments were blinded to group assignment. Results: 38 patients completed the 12 week study (ITU: n=37, Control: n=11.). The ITU group reported a significantly greater reduction in heel pain scores [Mean 8.27, SD 4.69, P=0.027] compared to the control group [Mean 2.25, SD 5.92] (Figure 1). Ultrasound imaging showed an 81% decrease in perifascial lesion size in the treatment group, compared to a 26% increase in lesion size in the control group (Figure 2). Conclusion: Preliminary results of this clinical study of noninvasive ITU for the treatment of chronic PF showed that ITU treatment as compared to sham control lead to a larger and more rapid reduction of heel pain and perifascial lesion size. ITU holds promise as a potential therapy to accelerate the healing of chronic plantar fasciitis