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Category: Ankle; Ankle Arthritis Introduction/Purpose: Computer Assisted Surgical (CAS) systems have been used successfully in joint arthroplasty to improve the accuracy of resections. CAS usage leads to reduced outliers and improved targeted alignment of orthopedic implants. Total ankle arthroplasty (TAA) is a surgical treatment for end-stage ankle osteoarthritis, and the latest generation of TAA is associated with favorable clinical outcomes as a modern alternative to ankle arthrodesis. Alignment of the implants during TAA is challenging because of limited surgical exposure and reliance on fluoroscopic alignment. Therefore, a TAA application for CAS system was developed using CT-based alignment alongside required fluoroscopy with the intent of facilitating the procedure and improving accuracy of bone resections. The objective of the study was to evaluate the accuracy and precision of the TAA CAS system. Methods: TAA was performed by a board-certified, fellowship-trained orthopedic surgeon on twelve artificial ankle joint specimens (PN1132-3, Pacific Research) using a CAS system (ExactechGPS, Blue-Ortho) featuring a dedicated ankle application. Scans of each of the twelve specimens were performed before TAA using a structured light industrial scanner. During the simulated surgery, active trackers were fixed to each specimen’s tibia and talus to allow registration of the anatomical landmarks. Bone resections were planned using template software to choose appropriate implant position and size relative to the bony anatomy. Resections on the talus included a flat cut with three degrees of freedom (e.g. varus, slope, and cut height), whereas tibial resections included distal and medial cuts with five degrees of freedom (e.g. varus, slope, axial rotation, medial offset and cut height). Finally, the resected bones were scanned and overlaid with the initial model for assessment of the error relative to the original plan. Results: For all eight angular and positional cut parameters across both the tibia and the talus, the mean signed overall intraobserver error was less than 2mm and 2° relative to the plan, and the 95% confidence interval was less than 2mm and 2°. Both angular and positional overall errors on the tibia were less than 1mm and 1° relative to the plan according to the mean and 95% confidence intervals. One deviation to surgical technique was identified with video tracking: The talar fixator was not tightened on specimen five which leading to tracker movement during talus resection. Therefore, the data from specimen five was removed from the analysis since the operative technique for the TAA navigation system was not followed. Conclusion: The results of the study show that the bone resections using the evaluated TAA application for CAS were associated with satisfactory accuracy level compared to conventional mechanical instruments and PSI blocks. Future work should consider additional surgeon users, cadaver specimens with ankle arthritis and/or deformity, and comparison to patient-specific instrumentation (PSI) and traditional conventional techniques. The results point to resections with errors of less than 2mm and 2° and therefore the system can offer both accurate and precise intraoperative surgical resection measurements during computer-assisted TAA. Total Ankle Arthroplasty with Enabling Technology Example tibial and talar plans and subsequent execution (top), Differences between planned resection and final measured resection, described as overall error (bottom)

Category: Hindfoot; Other Introduction/Purpose: Total knee arthroplasty (TKA), ankle arthrodesis/arthroplasty, and hindfoot arthrodesis are effective procedures in treating end-stage osteoarthritis and deformity of the knee and hindfoot, respectively. Risk of reoperation remains a significant complication associated with these major lower extremity surgeries. Our study aimed to evaluate revision/reoperation rates and etiologies in patients undergoing staged ipsilateral TKA and hindfoot reconstruction (HFR). Methods: A retrospective review identified 162 patients undergoing ipsilateral TKA and HFR procedures between 2000 and 2022. Groups were stratified according to their index surgery: TKA first (n=81) versus HFR first (n=81). Reoperations rates, complications, and indications were compared via descriptive statistics. Mean follow-up was 4 years from the second surgery. Results: For the TKA first cohort, the overall rate of any reoperation was 28% (23/81), including a significantly higher rate of HFR than TKA reoperations (22% vs. 7%, respectively, p< 0.01). The most common etiology for HFR reoperation was arthrodesis nonunion (8/18, 44%) whereas for reoperation indication for TKA was evenly divided between instability, aseptic loosening, and patellar dysfunction. For the HFR first cohort, the overall rate of any reoperation was 16% (13/81), including similar rates of HFR and TKA reoperations (9% and 10%, respectively, p=0.4). The most common etiologies of HFR and TKA reoperations after F&A surgery first were adjacent joint disease (6/7, 86%) and patellar-related complications (4/8, 50%), respectively. Conclusion: Reoperation after a HFR appears to be higher when an ipsilateral TKA is performed first, primarily due to arthrodesis nonunion. Our series represents a first report of the temporal relationship between TKA and ankle/hindfoot reconstruction.

Category: Hindfoot; Ankle Introduction/Purpose: Insertional Achilles tendinopathy (IAT) is a common pathology with multiple surgical interventions available for treatment. The Zadek, dorsal closing wedge calcaneal osteotomy (ZO) has been demonstrated to be effective treatment of IAT. There have been various recommendations in the literature as to what measurement of wedge removal should be considered ideal to produce greatest postoperative range of motion (ROM), thus postoperative biomechanical potential. Accordingly, the purpose of this cadaveric study was to assess the range of motion achieved after various measurements of wedge removal by ZO. Methods: The ZO was performed on six cadaveric specimens. A 7.5mm and 15mm osteotomy was marked and sequentially completed on each specimen. Lateral fluoroscopic imaging was utilized to take preoperative and postoperative ROM measurements for each osteotomy. Dorsiflexion (DF) and plantarflexion (PF) ROM arcs were measured for each wedge size and compared by t-test. Effect sizes were calculated by Cohen’s d analysis. Results: Maximal DF was 110.87±12.97 deg in the pre-osteotomy state. Removal of a 7.5mm wedge improved DF by 8 deg to a mean 102.93±13.81 deg (p=0.08). Removal of a 15mm wedge improved DF by 16 deg to a mean 95.96±11.41 deg (p=0.003). Cohen’s d and effect size calculation demonstrated a 7.5mm wedge to have a small effect on DF, while a 15mm wedge had a medium effect (0.29, 0.52 respectively). Maximal PF did not change significantly amongst the pre-osteotomy, 7.5mm wedge, or 15mm wedge positions. ICC was 0.96. Conclusion: Based on the results presented in this study, removal of a 15mm wedge with ZO yields significant and greater improvement in ROM than a 7.5mm wedge. We hope the current study will better inform preoperative planning for ZO.

Category: Ankle; Ankle Arthritis Introduction/Purpose: Computer Assisted Surgical (CAS) systems have been used successfully in joint arthroplasty to improve the accuracy of bony resections. CAS usage leads to reduced outliers and improved targeted alignment of orthopedic implants. The whole procedure is a suite of numerous surgical steps, and even using CAS systems, each of these steps may be associated with error such as mispositioning of the cutting block, play between the sawblade and the cutting slot due to the length and width of slot, or saw bending and skiving of the blade during the resection. However, the incidence of these errors may not be all equal. For this reason, the error sources of the individual surgical steps were evaluated for a novel image-based CAS system for total ankle arthroplasty (TAA). Methods: TAA was performed by a board-certified, fellowship-trained orthopedic surgeon on twelve artificial ankle joint specimens (PN1132-3, Pacific Research) using a CAS system (ExactechGPS, Blue-Ortho) featuring a dedicated ankle application. Scans of each of the twelve specimens were performed before TAA using a structured light industrial scanner. During the simulated surgery, active trackers were fixed to each specimen’s tibia and talus to allow registration of the anatomical landmarks. Bone resections were individually virtually planned and performed by the surgeon using template software to choose appropriate implant position and size relative to the bony anatomy. Finally, the resected bones were scanned and overlaid with the initial model for assessment of the error relative to the original plan. The abstract figure shows the flow of the procedure from plan to final cut as well as the outlay of the error measurements during slot positioning cut execution and cut verification. Results: Opportunities for error were identified during positioning, execution, and verification. Error from each step was also summated for an overall error value. Mean and 95 % confidence intervals for positioning, execution and verification errors were less than 2mm and 2° . Average absolute errors for the tibia were: 0.30°/.26mm for positioning, 0.87°/.53mm for execution, 0.89°/.56mm for verification, and 0.74°/.59mm overall. Average absolute errors for the talus were: 0.82°/.52mm for positioning, 0.41°/.51mm for execution, 0.64°/.62mm for verification, and 1.13°/.67mm overall. One deviation to surgical technique was identified with video tracking: The talar fixator was not tightened on specimen five per the operative technique, therefore, the data from specimen five was removed from the analysis. Conclusion: TAA performed with a CAS system resulted in overall error less than 2mm and less than 2° on all specimens. Design elements of the CAS system likely contribute to the low observed error. The surgeon receives visual confirmation of the plan and resection confirmation throughout the procedure which allows for real-time adjustments. The plan and the resection are confirmed during the procedure, and the cut itself can be refined. As a result, there is potential to remove the need for other checks for positioning guides which could reduce the burden on the user and reduce radiation exposure of the patient.

Category: Ankle; Trauma Introduction/Purpose: Flexible syndesmotic devices have been associated with a reduction in hardware complications, syndesmotic diastasis, and rehabilitation time. Current guidelines suggest syndesmotic devices should be placed specifically 1.5-3.0 cm above the tibiotalar joint, however some may argue that this precise guideline is not necessary. In many syndesmotic injuries, a fibula fracture can occur at this landmark, which may increase the risk of fracture displacement and entrapment of the non-absorbable suture within the fracture itself. The goal of placing a flexible syndesmotic device is to help the fibula “find its home” in the incisura. Therefore, specific proximity to the tibial plafond may be negligible. The current study compared outcomes, union rate, and complications associated with flexible syndesmotic device placement at varied distances from the tibial plafond. Methods: Flexible syndesmotic devices, were placed in patients with a confirmed fracture-associated syndesmotic injury on CT scan. Cases were retrospectively analyzed at a minimum one-year follow-up. 24 patients met our inclusion criteria for this study. 14/24 devices were placed between 1.5-3.0 cm from the tibial plafond (mean 2.26±0.35cm), while the other 10/24 were placed outside of this guideline (mean 4.30±0.64cm). On postoperative radiographs, the placement of each syndesmotic device was measured as a proximal distance from the tibial plafond. Cases were placed into cohorts, defined by device placement within or outside of the 1.5-3.0 cm guideline. Incidences of postoperative complication, revision surgery, radiographic nonunion, and hardware failure were recorded. Patient Reported Outcome Measurement System (PROMIS) pain, function, and mobility scores were recorded. Outcome measures of each study cohort were compared by t-test. Categorical data was compared by Chi-squared analysis. Results: Flexible syndesmotic device placement within current guidelines demonstrated improvement in PROMIS function (p=0.044), pain (p=0.032), and mobility (p=0.035) scores at postoperative follow-up. Similarly, device placement outside of the 1.5-3.0 cm guidelines demonstrated improvement in PROMIS function (p=0.010), pain (p=0.026), and mobility (p< 0.001) scores. There was one patient with a flexible syndesmotic device placed at 1.5-3.0 cm who experienced a traumatic break and wound infection secondary to noncompliance with non-weightbearing status. This patient required debridement, hardware removal, and eventually a below knee amputation. Amongst cases with devices placed outside current guidelines, there was one case of painful hardware, requiring removal (10.00%). There was no statistical difference noted in PROMIS pain scores or complications between the two cohorts. Conclusion: Current guidelines suggest the placement of flexible syndesmotic devices should be limited to 1.5-3.0 cm proximal to the tibiotalar joint. However, these guidelines may be outdated. The current study presents novel evidence that alternative placement of syndesmotic devices may lead to improvement in patient reported function, pain, and mobility, with a low complication rate. There was no evidence of nonunion in any patient in the current study; all cases maintained their syndesmotic reduction. This study may serve to better inform the scope of flexible syndesmotic device application in cases of ankle fractures requiring fixation of the syndesmosis.

Introduction/Purpose: Minimally invasive surgical (MIS) treatment of hallux valgus (HV) deformity is increasing in popularity. A 2mm-diameter burr is used to create a distal first metatarsal osteotomy prior to capital fragment translation and fixation. The metatarsal will shorten by the burr’s diameter (2mm). Plantar or dorsal capital fragment displacement may also cause load transference and possibly transfer metatarsalgia. In this study, we examine the effect of MIS HV on forefoot loading mechanics with respect to metatarsal shortening and sagittal plane displacement. Methods: Four lower-limb cadaveric specimens were studied. A pedobarography pressure-sensing mat was used to record forefoot plantar pressure in a controlled weightbearing stance position.10 Control and post-osteotomy measurements were obtained with the capital fragment fixated in 3 possible positions: 0mm, 5mm dorsal, and 5mm plantar displacement. Pedobarography data yielded pressure data within measurable graphical depictions. Raw mean contact pressure measurements were taken under the first and fifth metatarsal heads to establish medial and lateral forefoot loading pressure ratios. A priori power analysis was performed based on previous peer-reviewed pedobarographic data and our study was adequately powered. Results: 40 measurements were recorded and ratios of medial-to-lateral forefoot loading were constructed. Medial forefoot pressure change control versus 0mm displacement, and control versus dorsal displacement was not found to be statistically significant (p=0.525, p=0.55 respectively). Significant medial pressure increase was identified comparing control versus plantar displacement (p=0.006). Lateral pressure increased significantly with dorsal displacement of the osteotomy (p=0.013). Conclusion: MIS hallux valgus correction does not appear to cause increase in lateral forefoot pressure loading when sagittal plane displacements are controlled. Plantar displacement increases medial loading, and dorsal displacement increases lateral loading. The clinician must consider metatarsal head position post-osteotomy, as decrease in medial loading and subsequent increase in lateral loading may lead to lateral forefoot pain and transfer metatarsalgia.

Category: Hindfoot; Basic Sciences/Biologics Introduction/Purpose: Single-plane calcaneal osteotomies are used to manage hindfoot deformity. Neurological complications, such as tarsal tunnel syndrome, are well-documented following lateralizing calcaneal osteotomy. Traditionally, calcaneal osteotomy is performed using an oscillating saw. No studies have investigated the effect of alternative surgical techniques on postoperative tarsal tunnel pressure. The purpose of this study was to investigate the difference in tarsal tunnel pressures following lateralizing calcaneal osteotomy performed using a high-torque, low-speed “minimally invasive surgery” (MIS) Shannon burr versus an oscillating saw. Methods: Lateral-to-medial lateralizing calcaneal osteotomy via a lateral approach was performed on 10 below-knee cadaveric specimens. This was conducted on 5 specimens using an oscillating saw (Saw group) and 5 specimens using the MIS burr (Burr group). The calcaneal tuberosity was translated 1 centimeter laterally in all specimens and transfixed using 2 Kirschner wires. Tarsal tunnel pressure measurements were collected before and after osteotomy under ultrasound guidance using a percutaneous needle barometer. Mean pre- and post-osteotomy tarsal tunnel pressures were compared between groups. Differences were analyzed using Student’s t-test. Results: The mean pre-procedure tarsal tunnel pressure in the Saw group was 25.8 ± 5.1 mm Hg and 26.4 ± 4.3 mm Hg in the Burr group (p = 0.85). The mean post-procedure tarsal tunnel pressure was 63.4 ± 5.1 mm Hg in the Saw group and 47.8 ± 4.3 mm Hg in the Burr group (p = 0.01). The change in tarsal tunnel pressure after lateralizing calcaneal osteotomy was significantly lower in the Burr group (21.4 ± 4.5) compared to the Saw group (37.6 ± 12.5) (p = 0.03). The increase in tarsal tunnel pressure was 43% lower in the Burr group compared to the Saw group. Conclusion: In this cadaveric study, the increase in tarsal tunnel pressure following lateralizing calcaneal osteotomy was significantly lower when using a burr versus an oscillating saw. This is likely due to the increased width (“kerf”) of the 3mm MIS burr relative to the submillimeter saw blade width causing increased shortening of the calcaneus. This smaller magnitude of tarsal tunnel pressure increase suggests that use of the MIS burr for lateralizing calcaneal osteotomy may decrease the risk of postoperative tarsal tunnel syndrome. Future research in vivo should be aimed at investigating this.

Category: Trauma; Other Introduction/Purpose: Regional anesthesia has been increasingly used within orthopaedic surgery. It has been found to decrease opioid use and consumption and has been associated with decreased blood loss and clot formation in some lower extremity surgeries – specifically hip and knee arthroplasty surgery. General anesthesia is not without risks including malignant hyperthermia, laryngeal edema, vocal cord trauma, and delirium. This has led to increased utilization of regional anesthesia in foot and ankle surgery. However, there is a paucity of research that compares the postoperative outcomes in patients treated with regional compared to general anesthesia in these surgeries. We hypothesize the use of regional anesthesia in foot and ankle surgery leads to fewer short-term postoperative complications compared to general anesthesia. Methods: The American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database was queried from 2006-2018 to identify patients undergoing foot and ankle surgery. Current Procedural Terminology (CPT) codes for all foot and ankle surgery were utilized to determine which participants to include in the analysis. The cohort was divided into patients who received regional anesthesia versus those who received general anesthesia, and comparisons were made on demographic characteristics, and comorbidities, using chi-squared and t-test analyses. Multivariate logistic regressions were performed to identify whether lack of regional anesthesia was an independent risk factor for infection, minor postoperative complications, and major postoperative complications. Major postoperative complications included any complication that had a long-term effect on someone’s life or led to reoperation, while minor postoperative complications included any event that needed medical intervention but did not impact a person’s health long-term. Results: Using the ACS-NSQIP database and CPT codes, there were 12,764 participants for regional anesthesia and 73,481 participants who had general anesthesia. Utilizing logistic regression, this study found that the absence of regional anesthesia was independently associated with an increased risk for minor complications in foot and ankle surgery (Odds Ratio (OR) 1.34, 95% Confidence Interval (CI) [1.25-1.44], p=0.00). The absence of regional anesthesia was not associated with increased risk of major complications in foot and ankle surgery (OR 1.04, CI [0.96-1.12], p=0.32). Patients who received regional anesthesia were older and had more comorbidities than those without regional anesthesia used which may be a reason for the findings for major complications. Conclusion: Regional anesthesia independently reduced the risk of minor postoperative complications up to 30-days following foot and ankle surgery in this study. Patients undergoing foot and ankle surgery may benefit from augmenting their anesthetic plan with regional anesthesia.

Category: Hindfoot; Ankle Arthritis Introduction/Purpose: Subtalar arthrodesis (STA) is a common procedure used to correct rigid, arthritic hindfoot deformity. The deformity is often able to be corrected through the subtalar arthrodesis-site, however in severe deformity, calcaneal osteotomy (CO) may also be required to realign the hindfoot. CO may predispose the patient to additional risk of wound complication due to the proximity of sinus tarsi and open lateral calcaneal osteotomy incisions. Despite the relatively common nature of hindfoot deformity, there is no study to date assessing the complication profile and outcomes of combined STA and CO when compared STA alone. The purpose of this study was to compare STA alone versus STA and CO to examine union rates and complications for a procedure with known nonunion risk. Methods: A retrospective review of all STA performed two institutions between January 2011 and August 2021 was performed. All STA performed during that time period were identified using a CPT code search and chart review. 22 patients were identified with combined STA and CO as part of a simultaneous procedure. We then performed a matched pair analysis for STA only as a control group identifying 22 patients with STA only. Complications including delayed union or nonunion, removal of hardware, wound complications, and the need for revision surgery were recorded. The two groups were matched for age, gender, presence of diabetes, and smoking status. Differences were analyzed using a two-tailed Fisher’s exact test. Results: There were 22 patients in the STA and CO group with 22 included matched pairs as our control group . There were no significant statistical differences between the two groups when comparing for age and comorbidities. The STA group had 4 recorded complications, while the STA and CO group had 1 recorded complication in the follow-up period. There was no significant difference in complications between the STA and the combined STA and CO group (p= 0.6361). Radiographic union was identified with CT scan. All but 1 patient achieved union in the STA and CO group (nonunion ST only and not CO). 0 nonunions were identified in the STA control group. Post hoc power analysis demonstrates 81% power regarding union compared to historical controls. Conclusion: There was no statistically significant increase in complications when a calcaneal osteotomy was performed in addition to a subtalar arthrodesis, with no specific concern for wound complication. This data supports that performing a calcaneal osteotomy in combination with a subtalar arthrodesis may be utilized to prevent undercorrection of hindfoot deformity without additional wound complication risk. This study is limited by small study groups due to the severity of deformity required to have an additional calcaneus osteotomy. However it also highlights the importance of deformity correction as no additional risk of revision surgery was added.

Bone autografts are frequently harvested for use in foot and ankle surgery. A commonly used harvest site is the iliac crest; however, because of known morbidity with this site, the tibia and calcaneus are attractive alternatives. There remains limited understanding regarding the osteogenic potential of autografts from each of these locations. In this review, we provided an update of the known data on bone autografts from the iliac crest, tibia, and calcaneus, focusing on the total cells harvested from each site as well as the presence of osteogenic osteoprogenitor cells. Level of Evidence: Level V, expert opinion.

Category: Ankle; Trauma Introduction/ Purpose: Supination-external rotation (SER) ankle fractures are characterized by posterolateral translation and external rotation. In isolated fibula fracture SER variants, medial soft tissue structure incompetence can be identified with medial clear space (MCS) widening or with lateral talar subluxation (LTS), frequently obtained on stress view imaging. This assessment is a key determination of which patients may require surgical management to restore ankle joint stability. Current radiographic studies demonstrated increased sensitivity and specificity of LTS versus MCS which may be due to increased rotational movement occurring in the direction of the talar displacement. Biomechanical data has not yet been established. The purpose of this study was to investigate MCS and LTS displacements in a cadaveric biomechanical study to confirm this rotational movement principle in a controlled setting. Methods: An open approach was utilized to surgically create an SER isolated fibula fracture in five below-knee cadaveric specimens. Open anteromedial and lateral ankle approaches were created for visualization of the medial and lateral structures, also allowing direct measurement of the MCS and LTS with a ruler. There was no ankle instability prior to injury, MCS and LTS were zero in each specimen prior to experimental model creation. An SER-pattern fibular osteotomy was made with an oscillating saw. The superficial and deep deltoid were then released from the medial malleolus, and the foot was displaced maximally creating an SER-4b variant ankle fracture. The MCS and LTS were then measured. Differences were analyzed using a paired Student’s t-test. Effect size (Cohen’s d) was measured to characterize statistical significance and determine relative importance in the degree of change. Results: There was no underlying ankle stability, deformity, or arthritis in any of the 5 cadaveric ankle specimens. In our simulated SER-4b ankle fractures, the mean MCS widening using medial landmarks was 7.2 mm (+/- 1.3mm). The mean lateral displacement utilizing the LTS landmarks was 11.2mm (+/- 1.3mm). The difference between medial and lateral displacement was found to be statistically significant (p = 0.0067, 95% CI [1.85, 6.15]). Cohen’s d was equal to 3.1 (95% CI [1.24, 4.90]), demonstrating a large effect size, showing the mean to be different by 3 standard deviations. The increase in mean lateral displacement was 43% greater when compared to the mean medial displacement. Conclusion: In this cadaveric study, LTS displacement was significantly greater than MCS widening following simulation of SER type IV ankle fracture injuries. The effect size of 3.1 confirms statistical significance. This data supports that talus external rotation is a significant factor in SER pattern displacement. The rotational moment arm is largest laterally with external rotation, and posterolateral displacement. Our study supports the idea of measuring the LTS radiographically as a marker to assist in surgical decision-making. Further characterization of the displacement pattern of SER injuries will be helpful to assist surgical decision- making in these common ankle injuries.

Category: Midfoot/Forefoot Introduction/Purpose: Midfoot osteoarthritis affects up to 12% of the adult population greater than 50 years old. Arthrodesis is the traditional surgical procedure performed when nonoperative management fails but is a technically demanding procedure that requires prolonged postoperative immobilization and is not uncommonly complicated by nonunion or deep infection. The deep peroneal nerve (DPN) plays a significant role in afferent nociceptive midfoot joint pain perception, most consistently in the second and third tarsometatarsal joints and the naviculocuneiform joint. Early outcomes following DPN neurectomy have demonstrated promising results as a safe and effective treatment that allows early mobilization and weight bearing. The purpose of our study was to evaluate the mid-term patient satisfaction and pain relief after DPN neurectomy for treatment of chronic midfoot pain due to osteoarthritis. Methods: In this retrospective IRB-approved questionnaire-based study, we evaluated 49 out of 95 patients identified (56 feet) with an average follow-up of 34.6 (range, 9 to 51) months, who underwent DPN neurectomy (Figure 1) at our institution between September 2017 and February 2021. There were 39 women and 10 men, 42 unilateral (23 right, 19 left) and 7 bilateral procedures, with an average age of 67.9 (range, 35 to 88) years at the time of surgery. A questionnaire which included questions regarding post-surgical dorsal midfoot pain relief, surgical result satisfaction, and current functional limitations was administered via telephone. Demographic information, patient responses, and complications were recorded. Results: There was an 81.2% patient satisfaction with the result of the surgery in relieving their dorsal midfoot pain. Of the 49 patients, 84.9% would repeat the surgery under the same circumstances, 84.1% would recommend the surgery to a friend, 10.2% reported they wish they had undergone arthrodesis, 8.2% reported no pain relief in the first 6 months, and 55.8% reported current activity limitations because of dorsal midfoot pain. Six feet (10.7%) underwent a second procedure with an average postoperative time of 20.5 (range, 1 to 36) months. Complications include one patient with deep wound infection, one DPN neurectomy revision and burial into bone, one DPN neuroma excision, one midfoot exostosis excision, and two conversions to arthrodesis. Theoretic complications of neuroarthropathy, midfoot collapse, and development of lesser toe deformities were not observed. Conclusion: DPN neurectomy is a safe and effective surgical option for the management of chronic dorsal midfoot pain due to midfoot osteoarthritis after failed nonoperative management. At midterm follow-up, patients who underwent dorsal midfoot denervation reported acceptable satisfaction rates, similar to those reported for arthrodesis, with associated improved functional outcomes and few complications.

Category: Midfoot/Forefoot; Trauma Introduction/Purpose: The great toe plays a large role in activity, including maintenance of balance and substantial weight bearing capabilities. Fractures of the hallux distal phalanx, especially when displaced or unstable, can lead to significant dysfunction of the interphalangeal joint (IP) and pain and may need operative intervention. Surgical options include wire pinning, screw fixation, external fixation, arthrodesis, or amputation. For patients with significant comminution and shortening who would like to attempt toe salvage without fusion, external fixation can lead to great outcomes. Unfortunately, the use of these devices is hindered by cost, size, and availability. We recommend the use of a novel low cost external fixation device that can be made intraoperatively using common materials found in the operative room. Methods: A 27-year-old female, with a severely comminuted right distal phalanx fracture with interphalangeal (IP) joint dislocation, presented 4 days after a skiing accident. We discussed treatment may require IP joint arthrodesis or partial amputation, however, salvage fixation could be attempted initially. First, a transverse percutaneous wire was placed through the distal phalanx tip since the fragment was still mostly intact. The wire exited the skin medially. Two Kocher clamps to each side of the wire were applied for distraction of the fracture site while simultaneous manual manipulation of the more proximal fragments was performed. Once reduced, three more proximal transverse wires were placed through a 3cc syringe, which acted as a rail to hold the fracture length stable. The distal transverse wire was then impaled through the rail so that all four wires were within the rail providing two points of fixation in the distal phalanx and proximal phalanx. Results: The patient's weight-bearing status was non-weight bearing to the right lower extremity for 6 weeks. This was actually being dictated by the more proximal tibial plateau fracture for which she was non-weight bearing. With regard specifically to the hallux fracture, she could have been heel weight beared immediately. At her most recent post-operative visit at 6 weeks, she was doing well with minimal pain. The external fixation device was removed in clinic and she was transitioned to a post-op shoe and allowed to weight bear as tolerated. She was motor and sensate intact with the ability to actively range her IP joint. Radiographs at the most recent visit revealed excellent alignment of the toe with minimal articular step off. Conclusion: With severely unstable hallux distal phalanx fractures, operative intervention should be considered. For those with a significant degree of comminution who still would like to undergo salvage fixation, external fixation is an excellent option. Unfortunately, the use of these devices is hindered by cost, size, and availability. Hand surgeons solved this problem by introducing small, low cost external fixators composed of common materials such as needle sheaths, IV cannulas, and syringes. We adapted their model to the toes and were able to obtain great clinical outcomes with low cost, all the while maintaining the patient's expectations for cosmesis.

Category: Sports; Midfoot/Forefoot; Trauma Introduction/Purpose: Acute medial collateral ligament (MCL) tears of the great toe metatarsophalangeal joint (MTPJ) are a rare occurrence. There is minimal literature existing regarding both operative and non-operative management of this pathology, also known as 'traumatic bunion' due to its low incidence. The closest analog is a traumatic ulnar collateral ligament (UCL) rupture in the hand (Skier's thumb). Suture anchor repair with an internal brace has proven to be an effective treatment for thumb UCL tears with rapid rehabilitation and early range of motion. This method has not yet been reported in literature for a weightbearing joint such as the hallux MTPJ. We present a case report for a professional surfer with traumatic great toe MCL avulsion with surgical technique allowing rapid return to sport. Methods: We present a case report of a novel technique for this rare traumatic MCL avulsion. Surgical management of the great toe MCL was performed utilizing a pre-loaded interference screw to fixate suture at the MCL origin with suture tape augmentation. A mid-axial medial approach was used with L-shaped capsular flap to expose the MCL. 3-0 braided suture was passed through the proximal avulsed MCL. A drill tunnel was prepared at the MCL origin, and the MCL was repaired to its anatomic origin with an interference screw technique for knotless technique. The interference screw was preloaded with suture tape. The suture tape from the interference screw was passed extra articular and the capsule was repaired. The sutuer tape was then inserted into the MCL insertion on the distal phalanx using a small interference screw and drill tunnel for a suture tape augmentation while the toe was held in neutral MTPJ position. Results: He was made weightbearing as tolerated in a CAM boot post-operatively. Immediate active great toe MTPJ motion was permitted. At 2 weeks post-op, sutures were removed, and he was allowed self-directed passive range of motion of the toe, with continued weightbearing as tolerated in the boot. All restrictions were lifted at 4 weeks for a return to play protocol and the patient resumed surfing immediately at that time. His last follow up appointment was at 3 months post-op, at which time he had resumed full activity, had no deformity recurrence, no pain, and his range of motion was symmetric to the contralateral foot. The patient was able to compete at full activity in a national tournament to continue the professional tour at 3 months post- operatively. Conclusion: This report demonstrates a novel surgical technique for the treatment of a rare traumatic MCL avulsion of the great toe (the 'traumatic bunion'). In this case of great toe MCL repair in a professional surfer, we utilized a knotless technique to repair the MCL to it's anatomic origin and also provide suture tape augmentation to allow rapid rehabilitation. This report demonstrates rapid return to sport, an excellent outcome, easy rehabilitation, and straightforward surgical technique. More research will be needed to demonstrate the success of this technique in a broader population.

Category: Basic Sciences/Biologics; Other Introduction/Purpose: Bone autografts are frequently harvested for use in foot and ankle surgery. The gold standard harvest site is the iliac crest; however there is known morbidity with this harvest site. Alternative harvest sites include the tibia and calcaneus which are easily accessible for lower extremity surgery. Controversy exists regarding the osteogenic potential of autografts from each location. We performed a systematic review of the known data on cellular autografts from the iliac crest, tibia, and calcaneus focusing on the total cells harvested from each site as well as the presence of the critically important osteogenic osteoprogenitor cells. We also reviewed autograft volume, autograft consistency, surgical techniques, and the morbidities and complications associated with each bone autograft harvest location. Methods: In accordance with the PRISMA 2020 guidelines, a literature search of the PubMed, Cochrane Library, Web of Science, and Google databases from inception through January 2022 was performed. The search terms included: 'autograft,' 'bone graft,' 'foot and ankle surgery,' 'iliac crest,' 'tibia,' 'calcaneus,' reamer irrigator aspirator,' 'RIA,' 'mesenchymal cells,' 'osteoprogenitor cells,' 'quantity,' 'number,' 'amount,' 'yield,' 'concentration,' 'surface antigens,' 'surface markers,' 'CD markers.' Studies were included if autologous bone graft was harvested from the iliac crest, femur, tibia, or calcaneus and the cells in the harvest underwent histologic evaluation, quantification, or CD surface antigen identification. We included studies with bone graft as well as bone marrow aspirates used as samples. The nucleated cell and osteoprogenitor cell yield was recorded from each location; and MSC CD markers present at each harvest site were extracted from the eligible studies. Results: 13 studies met our inclusion criteria. Eight studies performed cell quantification from the harvest sites. Notably these studies only provide counting of total nucleated cells without specific identification of the osteoprogenitors. Colony-forming units were also reported and their findings are reviewed. Total cellular material was on average greatest in the iliac crest, with intermediate counts in the proximal tibia, and lowest in the calcaneus autograft samples. Five studies identified mesenchymal stromal cell (MSC) cluster of differentiation (CD) antigens at the harvest sites of interest. CD markers confirm osteoprogenitor cells are present in each sample location. Total number of osteoprogenitor cells remains unknown, however authors have attempted to extrapolate this number based on number of total nucleated cells and other data. Conclusion: Osteoprogenitor cells can be harvested from the iliac crest, tibia, and calcaneus. Greater total nucleated cell yields were identified in harvests from the iliac crest with descending amounts moving location distally in the limb. Nucleated cells were counted to provident estimates of osteoprogenitor cells yields in most studies, with flow cytometry confirmation that osteoprogenitors are present. Strict quantification of osteoprogenitor cells remains unknown. Multiple studies compared cellular material from bone marrow aspirates versus bone graft harvests themselves. Studies with modern techniques are needed to identify the true number of osteoprogenitors in each location.

Category: Trauma; Ankle Introduction/Purpose: Supination-external rotation (SER) variant ankle fracture is common, and identifying the unstable SER variants requiring surgery has been controversial. Stress view radiographs are frequently obtained to assist in decision-making. Measurement of the medial clear space (MCS) is used to determine medial structure integrity. SER variant ankle injuries are characterized by talus external rotation, and posterolateral translation causing a posterior displaced distal fibula fracture, with possible medial and posterior injury at further subluxation events. We propose that the MCS measurement is flawed by measuring from the point of rotational pivoting. Measurement of lateral displacement of the lateral talus versus the tibial plafond will be a more sensitive measurement tool for an injury mechanism characterized by external rotation and posterolateral subluxation. Methods: IRB-approved, retrospective review of ankle injury radiographs for acute SER-variant isolated lateral malleolar fractures during a 3-year consecutive period. Patients were included if they had a gravity-stress view (GSV) evaluation. Patients were excluded for different fracture morphology, pediatric fractures, no GSV films, or prior history of ankle or foot arthritis or trauma. A priori power analysis was performed demonstrating 32 patients would be required to detect a change in 2mm. 102 patients underwent analysis. GSV were analyzed with measurements taken of the medial clear space (MCS), superior clear space (SCS), and we propose two novel measurements of lateral talus subluxation (LTS) by comparison to the anterior ankle syndesmosis marked by a vertical line at the tibial plafond. Standardized measurements were acquired by foot-and-ankle fellowship-trained orthopaedic surgeons and musculoskeletal radiologists. ICC data was obtained. Surgeons separately provided blinded decisions- for-surgery which patients appeared to have ankle instability requiring surgical stabilization. Results: Measurements were performed for 102 patients, there were no significant differences in baseline demographics. There was a statistically significant increase in mean MCS, SCS, and LTS within the operative group (MCS 7.3 vs 5, p=0.005, SCS 4.6 vs 3.9, p=0.02, LTS 6.1 vs 2.9, p =5mm had a sensitivity of 95% and specificity of 60% in our cohort, LTS >4mm demonstrating the same sensitivity (95%) with improved specificity to 75%. Receiver-operator-characteristic analysis for MCS vs LTS demonstrates an area under the curve (AUC) 0.786 for MCS >4 versus LTS (AUC) 0.918. Conclusion: The LTS measurement is superior to MCS measurement as a surrogate for medial ankle structure stability. We propose that ankle joint subluxation can be more accurately identified by measuring nearer to the point of maximal talar displacement in an external rotation and posterolaterally displacing injury pattern. The LTS measurement elevation >4mm was found to be superior to the MCS measurement >4mm in all categories, with high sensitivity and specificity, and superior performance in ROC analysis. We propose this will be a useful tool for clinicians when evaluating SER variant ankle fractures.

Category: Hindfoot; Ankle; Other Introduction/Purpose: Equinovarus foot deformities typically present with equinus contractures, hindfoot varus, dorsiflexion of the medial midfoot, and adduction deformities of the forefoot. Whether of neurologic or muscular origin, all forms result muscular imbalance. Flexor hallucis longus (FHL) transfer to peroneus brevis (PB) is indicated when both peroneal muscles are in unrepairable condition to restore active eversion. However, in cases of muscle paralysis where the PB is still in continuity, we recommend a novel technique where FHL is tenodesed proximal to the peroneal retinaculum within the leg to avoid the additional morbidity associated with more distal fixation or tenodesis. Methods: Surgical intervention first involved a posterolateral approach to the ankle and an Achilles tendon Z-lengthening to fix her equinus contracture. The ankle and subtalar joint capsules were contracted requiring release. Flexor digitorum longus (FDL) and FHL were tenotomized, which immediately corrected her claw toes. Since the tendon had already been released, we were able to deliver the FHL tendon into the posterolateral leg wound. The peroneal fascia and sheath were opened proximal to the superior peroneal retinaculum to prevent tendon subluxation. PB was identified by confirming that it produced foot eversion and by visualizing the peroneus longus (PL). The tension of PB was confirmed by observing that it did not cause tension at PL insertion on the plantar 1st ray. FHL was then transferred to the PB utilizing a Pulvertaft weave technique with the tendon appropriately tensioned in mid eversion in the middle of the Blix curve (Figure 1). Results: After FHL transfer, the patient was immediately allowed to weight bear as tolerated in a short leg cast. This was due to her deconditioned state to limit atrophy and the effects of prolonged recumbency in this medically fragile young woman. The patient ultimately was casted for 10 weeks total as she was unable to tolerate a CAM boot or other orthotic due to the weight and problems with the fit. At 4 months follow up, her foot is corrected and she is able to stand in a neutral, plantigrade position. Using a new AFO, she can walk without issue. Her foot remains well balanced and plantigrade. Conclusion: This simple FHL transfer technique decreases morbidity since the transfer occurs within the leg, proximal to the superficial peroneal retinaculum (SPR). The transfer pulls on the paralyzed, but intact PB instead of routing the FHL to the 5th metatarsal base or PB stump. This technique is only recommended if PB is intact but non-functional. It should be noted that adequate tensioning is essential for a successful transfer. Benefits of this procedure include no cluttering under the SPR and no risk of scarring that region which can lead to decreased tendon excursion.

Category: Ankle Introduction/Purpose: Achilles tendon ruptures are common injuries, and an estimated 20-25% injuries are missed acutely. Chronic and acute Achilles tendon rupture patients typically present with nonspecific complaints and physical exam findings. Commonly used physical exam maneuvers such as the Thompson test have variable sensitivity and reliability for the examiner. The patient with an Achilles tendon rupture will have expected plantar-flexion weakness, however clinical data utilizing plantarflexion weakness to develop a physical exam maneuver is lacking. We propose two new tests with sensitivity and specificity analysis to evaluate this understanding in the clinical setting: the Stand and Maintain Plantarflexion (STAMP) and Tendo-Achilles Rise (TAR) tests. We hypothesize that the STAMP and TAR exams maneuvers will have high sensitivity for diagnosis of acute and chronic Achilles tendon rupture. Methods: Data was collected from a single surgeon's practice at two large urban treatment centers. Data was retrospectively acquired over a period of 7 years and then prospectively acquired over a period of 5 years. Patients with mid-substance Achilles tendon rupture confirmed with MRI imaging or operative treatment were included. We examined clinical data regarding ambulation, resting tension, palpable Achilles gap, Thompson test, and STAMP and TAR tests on initial presentation. The STAMP test is performed by the patient attempting a wall assisted double leg heel rise and lifting the uninjured foot off the ground. It is consistent with an Achilles tendon rupture if the patient is unable to maintain this position for five seconds. The TAR test is performed by the patient attempting a wall assisted single leg heel rise. It is consistent with an Achilles tendon rupture if the patient is unable to maintain this position for five seconds. Results: 71 patients with complete mid-substance Achilles tendon ruptures that met inclusion criteria were identified. 45 (63%) presented acutely and 26 patients (37%) presented chronically. The Thompson test displayed a diagnostic sensitivity of (12 26 46%) for chronic ruptures and (38 45 84%) for acute ruptures. The STAMP and TAR tests displayed a diagnostic sensitivity of (22 26 85%) for chronic ruptures and (45 45 100%) for acute ruptures with a diagnostic specificity of (89%). Conclusion: Achilles tendon ruptures can be difficult to diagnose due to inconsistent symptoms and clinical exam findings. The STAMP and TAR physical exam tests have high sensitivity to clinically diagnose Achilles tendon rupture both in the acute and chronic setting and are superior to well-described physical exam tests. The findings support that the addition of the STAMP and TAR diagnostic protocol may be clinically beneficial when diagnosing Achilles tendon ruptures in both the acute and chronic setting. Future work should be focused on providing direct comparison to other exam maneuvers as well as identifying data reliability.

Category: Ankle; Hindfoot; Midfoot/Forefoot; Other Introduction/Purpose: Charcot-Marie-Tooth (CMT) disease is an inherited progressive neurologic disorder characterized by extremity deformities and functional deficits. Surgery is indicated for substantial functional deficits and severe deformity. Reconstructive surgery is individualized and multifaceted to correct the cavovarus deformity, and maximize function with tendon transfers and joint stabilization procedures. No previous study has reported improvement from pre-operative baseline patient reported outcome measures to post-operative outcome measures. We studied PROMIS scores and patient satisfaction surveys to report improvements in physical function, pain interference, and depression. Our hypothesis was that CMT patients' preoperative baseline would be significantly worse than the control population in all domains, and that they would experience demonstrable improvement greater than the minimally clinically important difference (MCID) for the 3 PROMIS score domains tested post- operatively. Methods: Prospective PROMIS scores were collected on 147 feet in 89 patients who had reconstructive foot surgery for CMT during a 40-month period (June 2016-December 2020) by a single surgeon. Radiographic and clinical data were recorded prospectively to identify complications. Each patient completed a battery of physical function (PROMIS-PF), pain interference (PROMIS-PI), and mood/depression (PROMIS-M) instruments pre-operatively, every 3 months for the first post-operative year, and annually thereafter. Pre-operative PROMIS scores are reported for patients prior to any surgery on either foot to establish a functional baseline. Post-operative PROMIS values are reported only after the last planned surgery was completed in the common setting of staged bilateral surgeries. Patient satisfaction surveys were administered at last follow-up. Post-operative complications were recorded. Statistical analysis was performed with students t-test for continuous variables and chi-squared analysis for categorical variables. PROMIS scores are reported as mean (+/- standard deviation). Results: 41 patients met inclusion criteria for reporting pre-operative baseline PROMIS scores, and 57 patient's post-operative PROMIS data were included after the final reconstructive surgery within the study window. Mean follow-up was 26 months. Pre- operative baseline PROMIS demonstrate CMT patients have worse PROMIS-PF, PROMIS-PI, and PROMIS-M than the population which is statistically and clinically significant. All PROMIS domains were improved by clinically and statistically significant values. PROMIS-PF improved from 38 (+/-6) to 46 (+/-5), a 4-5x improvement over MCID (2). PROMIS-PI improved from 59 (+/-8) to 51 (+/-7) representing a 1-2x improvement in the MCID (4). PROMIS M improved from 53 (+/-10) to 49 (+/- 5) achieving MCID 2. >90% were highly satisfied and would undergo surgery again. There were 7 complications: 1 deep infection, 2 superficial infections, 1 superficial wound dehiscence, and 3 unplanned hardware removals. 5/7 of these patients experiencing complications remained 'satisfied' or 'very satisfied'. Conclusion: Patients with CMT disease have baseline functional deficits in physical and mental health as judged by PROMIS measures that were worse than the population means in all 3 tested domains. Surgical reconstruction produced clinically significant improvements in PROMIS-PI, PF, and M domains at up to 4 years of follow-up. Patients were highly satisfied with the results with an acceptable rate of post-operative complications.

Category: Hindfoot; Other Introduction/Purpose: The hindfoot deformity seen in Charcot-Marie-Tooth disease (CMT) is poorly understood, and the contribution of abnormal bone morphology has never been conclusively demonstrated. The purpose of this study was to compare the three-dimensional (3D) bone morphology of the talus, calcaneus and navicular in a cohort of CMT patients versus a control population. We used the data obtained from weight-bearing computed tomography (WBCT) to reconstruct the geometric shape of each bone using 3D surface meshing techniques. Surface mesh analysis of this type is commonly used in engineering to evaluate and optimize 3D geometries and structures. Methods: A total of 17 WBCTs from 15 patients (average age 24) with CMT who underwent WBCT without previous surgeries, degenerative changes or open physes were included. These were compared to 20 healthy control WBCTs. Calcaneal measurements included the radius of curvature and the angle between the posterior tuberosity and posterior facet in the sagittal plane. Talar measurements include axial and sagittal declination between the body and neck as well as coronal rotation of the talar head relative to the body. Surface-mesh model analysis was performed comparing the average of the CMT cohort to the controls using CT analysis software (Disior Bonelogic). Means were compared with a t test (p

Category: Basic Sciences/Biologics; Other Introduction/Purpose: Effective pain treatment remains elusive in the orthopedic foot and ankle practice as evidenced by the variable experience of pain, post-operative or otherwise. Intrinsic pain tolerance is likely contributing to this variability in the patient's experience of pain. Pressure dolorimetry is a validated, objective measure to assess pressure sensitivity and is correlated with pain tolerance. No previous study in the orthopedic foot and ankle literature has attempted to correlate objective versus subjective pain tolerance. General mental health is associated with central pain sensitization and may also affect pain tolerance. Our hypothesis was that subjective self-assessment of pain tolerance would be correlated with objective dolorimetry. We hypothesized that mental patient-reported outcome scores would also be correlated to objective pain tolerance. Methods: Prospectively-collected patient-reported outcome scores (PROMIS), dolorimetry measurements, and survey data of subjective reported pain tolerance were collected pre-operatively on 50 consecutive patients by two surgeons in an urban orthopedic foot and ankle practice. Patients were included if they had normal sensation on the plantar foot and no prior surgery or plantar heel source of pain. Each patient underwent objective measurement of their ability to withstand pressure applied to the plantar heel causing 5/10 pain using a hand-held dolorimeter with digital pressure measurement display. Each patient was administered a preoperative battery of PROMIS physical function (PF), pain interference (PI), and mood/depression (M) instruments, and a separate survey where they scaled their subjective tolerance to pain and discomfort. Statistical analysis was performed utilizing students t-test for continuous variables. Correlations were evaluated with Pearson's R coefficient. Data are reported as means (+/- standard deviation) unless otherwise noted. Results: 50 patients received hand-held dolorimetry measurements, completed the pain tolerance survey, and completed PROMIS measures. Dolorimetry data from the plantar heel was normally distributed with mean force 24 N/cm 2 (+/-10) to reflect a 5/10 pain experienced by the patient. Patients were shown to estimate their pain threshold with mean subjective pain threshold 6.8/10 (+/-2) regardless of objective pain data or PROMIS scores. The mean PROMIS scores of the sample were PF (41+/-8), PI (60+/-7), and M (49+/-9) reflecting a sample with decreased physical function and increased pain which could be expected in an outpatient foot and ankle clinic. There was a negative correlation of R=(-0.432) regarding PROMIS-M with dolorimetry objective pain tolerance which was statistically significant (p60) had a statistically significant decrease in pain threshold to 18+/-8 N/cm 2 compared to 30 +/- 9 N/cm 2 for those who were less depressed (p

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: The cavovarus deformity of Charcot-Marie-Tooth (CMT) disease typically presents with hindfoot varus and forefoot valgus. This seemingly paradoxical relationship is poorly understood. Better insight into this complex three- dimensional alignment under physiologic load-bearing conditions is possible using weight-bearing computed tomography (WBCT). This is the first study to examine the extreme rotational deformity in the midfoot of CMT patients, and thereby provides a key to the successful operative correction of the CMT cavovarus foot. Methods: We retrospectively reviewed the WBCTs of patients with CMT who presented to a single surgeon. Those with history of bony surgical correction, severe degenerative joint disease, or open physes in the foot, were excluded. Scans were analyzed using three-dimensional analysis software (Disior Bonelogic) to generate axes of select bones and their relationship relative to the tibial plafond anterior-posterior axis in the axial plane. The coronal alignment of the foot involved angular measurements of the calcaneus, talar dome, midfoot and forefoot relative to the ground. We reported quantitative alignment parameters and compared the measurements to WBCT of 20 controls. Results: 17 WBCT scans from 15 CMT patients (average age 24 years) met criteria for inclusion. In the axial plane, external rotation of the distal tibia accounted for the varus heel position rather than subtalar malalignment. The greatest change in axial alignment occurred between the talar neck and navicular (26 degrees). The average talonavicular (TN) medial uncoverage angle was -15 degrees for CMT patients, indicating medial overcoverage, compared to +11 degrees for controls, (p

Category: Trauma; Other Introduction/Purpose: Knee flexion has been demonstrated to impede popliteal venous return with large effect size among patients lying supine for surgery. Passive popliteal flow impedance has also been suggested to occur with knee scooter usage due to knee flexion. This study compared the effect of knee flexion angles on popliteal venous return between upright, crutch and knee scooter positioning when immobilized. Further, the countervailing effect of standardized hallux musculovenous pump activation was observed. Methods: This was an IRB approved study of young, healthy volunteers. Popliteal venous diameter and flow metrics were assessed with venous ultrasonography and compared between straight leg, crutch, and knee scooter positioning while wearing a walking boot and nonweightbearing. Flow was assessed with muscles at rest and with hallux musculovenous pump activation via active oscillation between hallux metatarsophalangeal joint extension and flexion at one motion per second (0.5 Hz) as paced by a metronome. Observer consistency was assessed. Paired-sample Student’s t-test and the Wilcoxon signed rank tests were used to assess within-subject differences for diameter and venous flow parameters, respectively. Knee flexion and musculovenous pump activation effects sizes were calculated. A priori sample size indicated 24 subjects were needed to achieve 80% power to detect a significant ( p < 0.006 ) difference in medial flow for any of 8 comparisons, assuming large effect sizes. Results: 16 of 24 (67%) subjects were female. Twelve limbs (50%) were right sided. The mean age was 21.9 years (SD 3.0 years) and the mean body mass index was 21.9 (SD 1.9). Observer consistencies were excellent (0.93 to 0.99). No significant differences in mean vessel diameter, time-averaged mean velocity, and total volume flow occurred. Corresponding knee flexion effect sizes were small (range -0.04 to -0.26). A significant decrease (-24%) in active median time-averaged peak velocity (TAPV) occurred between upright and crutch position (20.89 cm/s vs. 15.92 cm/s, p < 0.001) with a medium effect size (-0.51). Hallux musculovenous pump increased all flow parameters (all p< 0.001) and effect sizes were comparatively larger (>0.6) across all knee flexion positions. Conclusion: Compared to values reported for supine individuals, upright passive popliteal venous return was observed to be markedly diminished at all knee flexion angles. Knee flexion had minimal effect on diameter, a small effect in further diminishing TAMV and TVF and a medium effect on diminishing TAPV. Hallux musculovenous pump activiation had a large effect on increasing flow at all knee flexion angles. Patients may well be counseled to use toe motion to counter the negative effects of gravity, and to a lesser extent knee flexion, when using crutches and knee scooters while their ankle is immobilized.

Background: Accurate glenoid component placement in shoulder arthroplasty is often difficult even with the use of preoperative planning. Computer navigation and patient-specific guides increase component placement accuracy, but which patients benefit most is unknown. Our purpose was to assess surgeons' accuracy in placing a glenoid component in vivo using 3-dimensional preoperative planning and standard instruments among various glenoid wear patterns. Methods: We conducted a retrospective review of 170 primary anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) performed at a single institution. Commercially available preoperative planning software was used in all arthroplasties with multiplanar 2-dimensional computed tomography and a 3-dimensional implant overlay. After registration of intraoperative bony landmarks to the navigation system, participating surgeons with knowledge of the preoperative plan were blinded to the computer screen and attempted to implement their preoperative plan by simulating placement of a central-axis glenoid guide pin. Two hundred thirty-three screenshots of surgeon's simulated guide pin placement were included. Glenoid displacement, error in version and inclination, and overall malposition from the preoperatively planned target point were stratified by posterior wear status (with [Walch B2 or B3] or without [A1, A2, or B1]) and Walch classification (A1, A2, B1, B2, or B3). The glenoid component was considered malpositioned when version or inclination errors exceeded 10° or the starting point displacement exceeded 4 mm. Results: For rTSA, errors in version were greater for glenoids with posterior wear compared with those without (8.1° ± 5.6° vs. 4.7° ± 4.0°; P 10° compared with those without (31% vs. 8%; P