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Category: Midfoot/Forefoot Introduction/Purpose: Functional hallux rigidus is characterized by limited first metatarsophalangeal (MTP) dorsiflexion during weight bearing conditions, but normal motion when the metatarsal is allowed to plantarflex. This phenomenon alters the mechanics of the foot, potentially leading to lateral column overloading and dynamic cavovarus. Furthermore, it is suspected that the abnormal forces across the first MTP alters its biomechanics, leading to cartilage destruction and eventual structural hallux rigidus. The purpose of this study is to assess the role of the flexor hallucis longus (FHL) and plantar fascia in functional hallux rigidus and to determine the best surgical treatment. Methods: Six cadaveric lower limbs disarticulated at the hip were analyzed. The feet were positioned manually in the same manner that would be used in a clinical exam of patients. The examiner's thumb was used to stabilize the first metatarsal head and prevent plantarflexion to simulate the closed-chain kinetics of weight bearing. The same hand was used to hold the ankle neutrally aligned to the leg. The other hand was used to maximally dorsiflex the great toe. X-ray was used to obtain images of the feet. The plantar fascia was transected with a Z cut, shortened approximately 5 mm, then repaired. The fiberosseous tunnel was released. The FHL was transected with a Z cut then shortened approximately 5 mm. Great toe dorsiflexion was assessed and X-rays taken after each of the manipulations. Range of motion of the first MTP was measured on Xrays and analyzed using Student's T-test. Results: Average passive dorsiflexion of the first MTP is 29.8° (range 17-46°) prior to manipulation. Shortening the plantar fascia and FHL did not decrease the MTP dorsiflexion significantly beyond baseline (P = 0.08, 0.09 respectively). Transecting the plantar fascia increased the dorsiflexion by 14° (standard deviation (SD) 9.5) and transecting the FHL increased dorsiflexion by 13.7° (SD 4.0). Dorsiflexion increased significantly beyond baseline with both these methods (P = 0.02 and P < 0.001 respectively), but the difference between the two methods was not significant (P = 0.93). Releasing the fiberosseous tunnel alone increased the dorsiflexion 8.8° (SD 5.7). Increased dorsiflexion beyond baseline was significant (P = 0.03). The increase in dorsiflexion with fiberosseous tunnel release was not significantly different than transecting the plantar fascia or the FHL (P = 0.40 and 0.42 respectively). Conclusion: By definition, functional hallux rigidus is diagnosed when first MTP dorsiflexion cannot reach 60°. Its prevalence may be more widespread than previously identified. Both the FHL and plantar fascia are implicated in functional hallux rigidus, as transection of either improves the dorsiflexion of the great toe. However, accessing the plantar fascia comes with significant risks and complete transection of the FHL is not feasible. As an alternative, releasing the fiberosseous tunnel is a simple, minimally morbid procedure that can also significantly improve functional hallux rigidus to a similar degree.

Category: Ankle; Ankle Arthritis Introduction/Purpose: Even as its popularity increases, there remain many unanswered questions regarding total ankle arthroplasty. One debate considers how best to restore proper rotation of the talar component relative to native, non- osteoarthritic anatomy. At present, two common schools of thought are to parallel the talar component rotation with the medial gutter line or to choose a line that bisects the gutters. These axis' are then considered with respect to a chosen foot axis, often defined by the second metatarsal or second toe clinically. The present study sought to define the foot center axis relative to the ankle on weight-bearing CT in patients without ankle osteoarthritis to inform talar component positioning in total ankle arthroplasty. Methods: Following IRB approval, charts were reviewed to identify patients without ankle osteoarthritis, trauma or other deformity who received a weightbearing CT scan. A pilot group of n=34 patients were included for a total of n=50 limbs. Average age was 50.3 +/- 7 and there were = 54% female patients. All measurements were made on MPR (multiplanar reformation) axial reconstructions. Cobb angle measurements between the anatomic foot center, the second, the fourth metatarsal and the gutter bisector or medial gutter line were recorded. Statistical analysis was performed by IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY. Results: The mean gutter bisector angle was 5.7 deg +/- 2.0. The mean cobb angle between the anatomic foot center and the medial gutter line was 6.1 deg +/- 4.4 and between the anatomic foot center and gutter bisector was 6.3 deg +/- 4.8, there was no statistical difference between measurements (p=0.62, Table 1). The mean cobb angle between the second metatarsal and the gutter bisector was 9.9 deg +/- 6.8, whereas the mean cobb angle between the fourth metatarsal and the gutter bisector was 7.5 deg +/- 5.2, which was not statistically significant (p=0.053). There was no statistical difference between mean cobb angle measurements between the anatomic foot center and the gutter bisector and the fourth metatarsal and the gutter bisector (p=0.243), but there was statistical difference between mean cobb angle measurements of the second metatarsal and the gutter bisector and the anatomic foot center and the gutter bisector (p=0.003). Conclusion: The axial alignment of the foot center axis relative to the ankle in patients without deformity or osteoarthritis is most collinear with the medial gutter line. In general, the axial alignment of the ankle joint relative to the foot in patients without osteoarthritis tends towards

Category: Ankle; Ankle Arthritis Introduction/Purpose: Even as its popularity increases, there remain many unanswered questions regarding total ankle arthroplasty. One debate considers the proper rotation of the talar component to restore native, non-osteoarthritic anatomy. The foot center axis is a unique anatomic concept that considers the position of the native foot relative to the ankle. The present pilot study sought to evaluate the reproducibility of axial alignment measurements, including the foot center on weight-bearing CT in patients without ankle osteoarthritis. Methods: Following IRB approval, charts were reviewed to identify patients without ankle osteoarthritis, trauma or other deformity who received a weightbearing CT scan. A pilot group of n=8 patients were included for a total of n=10 limbs. Average age was 50.1 +/- 14 and there were 38% female patients. All measurements were made on MPR (multiplanar reformation) axial reconstructions. Cobb angle measurements between the anatomic foot center, the second, the fourth metatarsal and the gutter bisector or medial gutter line were recorded by n=4 observers. Intraclass correlation (ICC) was produced using a two-way random effects model with absolute agreement and other statistical testing was performed by IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY. Results: The average gutter bisector angle was 6.2 deg +/- 2.0 and the average angle between the medial base of the 1st metatarsal head, lateral base of the 5th metatarsal head and the posterior calcaneus was 33.0 deg +/- 2.6. Amongst the observers, the ICC for these landmarks were 0.95 and 0.96 respectively. The average cobb angle measurement between the gutter bisector angle and the second metatarsal was 8.3 deg +/- 7.3, with a corresponding ICC of 0.96. The average cobb angle measurement between the gutter bisector angle and the anatomic foot center was 5.6 deg +/- 4.3 and the average cobb angle measurement between the medial gutter line and the anatomic foot center was 6.23 deg +/- 6. Amongst the observers, the ICC for these measurements were 0.81 and 0.81 respectively. Conclusion: In a small pilot study of patients without osteoarthritis who underwent weight-bearing CT scans there was good (ICC>0.75-0.90) to excellent (ICC>0.90) agreement amongst observers for measurements of foot center axis and ankle rotation. These findings validate the reproducibility and agreement of these manually constructed measurements for assessing the relationship between the foot center axis and ankle rotation. Future studies will expand upon the use of these measurements to define non-arthritic anatomy. The anatomic foot center may be a useful guide for establishing intra-operative foot orientation when performing total ankle arthroplasty.

Category: Lesser Toes; Midfoot/Forefoot Introduction/Purpose: Hammertoe deformities are the most common pathology of the forefoot, accounting for up to 48% of all forefoot operations. There is currently limited evidence documenting differences in foot radiographs and radiographic measurements that may represent a predisposition to developing hammertoe deformity. The purpose of this study was to investigate whether patients with hammertoe deformity demonstrate increased radiographic measurements of first, second, or third metatarsal (MT) lengths as well as Meary’s angle compared to a healthy control group. Methods: Following IRB approval, an institutional radiology database was queried from January 2009-2018 for patients with ICD- 9 and ICD-10 diagnosis codes for hammertoe deformity of the 2nd or 3rd phalange. Control cases were selected using diagnosis codes for acute plantar fascial pain in the same timeframe with medical record review to exclude patients with prior lower extremity injury, surgery or pathology. 234 hammertoe and 110 control patients met inclusion and exclusion criteria. Automated 1:1 case-control matching was performed to control for age, sex and laterality. Following matching, the sample size consisted of 80 patients in each cohort. Proximal to distal end-to-end articular surface radiographic lengths were documented for metatarsals and phalanges of the 1st, 2nd and 3rd rays on anteroposterior radiographs. Lateral talar-first metatarsal (Meary’s) angle was measured using weightbearing sagittal radiographs by calculating the angle formed by lines that bisect the talar neck and anatomic neck of the first metatarsal. Results: A total of 160 patients (80 cases and 80 controls) were included in the study. Mean age was 47.7 years among hammertoe cases and 47.5 years among controls (p=0.92). 54 of 80 cases in each group were female. There was a statistically significant increase in the average Meary’s angle among hammertoe patients (5.23 +- 8.60°) compared to controls (2.15 +- 5.96°) (p

Category: Ankle, Midfoot/Forefoot, Opioid Use Research Introduction/Purpose: Within the United States, opioid abuse has become a national crisis. Twenty-nine percent of patients prescribed opioids misuse them with nearly 12% developing addiction. One previous study has shown that patients undergoing foot/ankle surgery were left with extra narcotic pain medications following surgery, many of whom would have preferred to dispose of them. Our purpose was to evaluate factors in foot and ankle surgery that are associated with increased risk of prolonged post-operative opioid pain medication usage and identify the risk of various post-operative complications that may be associated with pre-operative opioid usage. We hypothesize that pre-operative opioid use will place patients at an increased risk of post-operative usage. Methods: The MarketScan commercial claims and encounters database, including approximately 39 million patients per year, was searched to identify patients who underwent foot/ankle surgery based on CPT code from 2005-2014. Preoperative comorbidities including DSM-V mental health disorders, chronic pain, chronic regional pain syndrome (CRPS), obesity, tobacco use, medications and diabetes were queried and documented. Patients who utilized opioids at least one month up to 3 months prior to surgery were identified. This timeframe was chosen to exclude patients who had been prescribed post-operative narcotic medications up to 1 months pre-operatively. We utilized odds ratios (OR), 95% Confidence Intervals (CI), and regression analysis to determine factors that are associated with prolonged post-operative opioid use at 3 time intervals. Results: 112,893 patients underwent foot/ankle surgery. 11,523 (10.2%) patients utilized opioids 1-3months pre-operatively. Of those, 5,732 (5.0%) utilized opioids post-operatively at 6 weeks, 4,364 (3.8%) at 3 months, 3,475 (3.08%) at 6 months and 2,579 (2.2%) at 1 year. Pre-operative opioid use was associated with increased post-operative use (6-12weeks: OR 7.24, 95% CI 6.92- 7.58; 3-6months: OR 11.03, 95% CI 10.45-11.63; 6-12months: OR 14.1, 95% CI 13.3-15.1; >12months: OR 14.74, 95% CI 13.68-15.88). Tobacco use, chronic pain, DSM-V diagnosis and non-opioid analgesia yielded increased risk of post-operative opioid usage. Diagnosis of CRPS, obesity or diabetes did not have an increased risk. Pre-operative opioid use was associated with an increased risk of readmission, DVT, pulmonary embolism, I&D of surgical site, myocardial infarction, UTI and post-operative bleeding (Table 1). Conclusion: Our study found a number of factors that are associated with prolonged post-operative opioid usage which included pre-operative opioid use 1-3months before surgery, tobacco use, chronic pain, DSM-V diagnoses and pre-operative use of certain non-opioid medications. We also found patients with pre-operative opioid exposure to be at an increased risk of a number of significant post-operative complications, including an increased risk of readmission at 30 and 90 days. This data provides orthopaedic surgeons a number of variables to consider when determining post-operative analgesia strategies, and provides health systems, providers and payers information on complications associated with pre-operative opioid utilization.