The Effect of Focused Vibration on Tibialis Anterior Function in Normal Subjects

Category: Basic Sciences/Biologics; Other Introduction/Purpose: Foot drop is a debilitating condition which may be caused by peripheral nerve pathology. Focused vibration therapy (FVT) is a novel treatment in this setting which aims to improve the response of muscle motor units to nervous stimuli, improving muscle function and rehabilitation potential. This study investigates the effect of FVT on tibialis anterior (TA) function in normal subjects to determine the optimal timing of application. Methods: Fifteen normal subjects with mean age 25.47±3.27 years and BMI of 21.93±1.54kg/m 2 were recruited. Using surface electromyography (EMG), a rotary potentiometer, video analysis (KINOVEA software), and force gauges, the activity of TA, ankle range of movement (ROM), and force at maximal isometric voluntary contraction (MVC) in dorsiflexion were measured. Baseline TA strength was recorded, and participants then performed a series of dorsiflexion exercises to induce fatigue. Strength measurements were repeated after a 5-minute rest period (control). This process was repeated with FVT applied before exercise (FVBE) and after exercise (during the rest period, FVAE). FVT was delivered over the TA muscle belly at 75Hz / 0.4mm amplitude. Data was analysed using ANOVA. Results: There was no significant change in EMG readings or dorsiflexion ROM between baseline, control and FVBE/FVAE measurements. Compared to baseline, MVC increased by 10.87N (6.6%) after FVBE (p=0.034) and 13.87N (8.4%) after FVAE (p=0.034). Compared to control, MVC did not increase significantly with FVBE, but did increase by 7.70N (4.3%) following FVAE (p=0.049). Conclusion: FVT improved the MVC of TA - this was most pronounced when FVT was applied during the recovery phase, after exercise. The lack of EMG / ROM improvement is expected in normal subjects. Our results suggest that FVT is more effective than passive rest and may enhance muscle strength recovery. Further work will investigate the optimal dose of FVT and response in patients with pathology

UK Foot and Ankle Thrombo-Embolism Audit (UK-FATE): A Multicentre Prospective Study of Venous Thromboembolism in Foot and Ankle Surgery

Category: Other Introduction/Purpose: There is wide variation in the threshold and provision of thromboprophylaxis in the treatment of foot and ankle conditions. One of the difficulties in affecting change in practice in this area is the low incidence of postoperative, symptomatic VTE. Therefore, a large number of patients need to be included in any series for meaningful conclusions to be drawn. Primary objective To observe the UK-wide variation in post-operative thromboprophylaxis, and to analyse the 90-day incidence of symptomatic venous thrombo-embolism related to: -Elective foot and ankle surgery -Trauma foot and ankle surgery -Treatment of Achilles tendon ruptures (operative and non-operative) Methods: This was a multi-centre prospective audit spanning a collection duration of 9 months. Primary outcomes included symptomatic VTE up to 90 days following foot & ankle surgery and Achilles tendon rupture and VTE related mortality up to 90 days following treatment. Secondary outcomes included methods of thromboprophylaxis used, and possible confounding variables and influencing factors for VTE. Results: A total of 10,983 patients were included from 56 sites in the UK. This was split into 51.72% trauma (n=5571), 3.78% diabetic surgery (n=415) and 45.18% elective surgery (n=4962). There was 95 VTE events across the whole cohort (0.86%). Diabetic foot disease surgery had the highest rate of VTE (Below knee amputation 5.3% and acute foot debridement 2.6%). The trauma diagnosis with the highest rate of VTE was Achilles tendon rupture (3.7%). All elective foot procedures had a VTE rate < 1% except elective tendon procedure (1.1%). Factors with statistically significant association with VTE included trauma surgery where prophylaxis stopped greater than 1day pre surgery (p=.027), non-compliance with prophylaxis (p=.001), post-surgical infection (p=.005), and the comorbidities asthma (p=.014), cancer (p=.014), dementia (p=.001), diabetes (p=.005), stroke (p < 0.001) and recent long-distance travel (p=.048). Conclusion: This is a large-scale multicentre study which recorded multiple possible confounding variables. There were 12 different chemical prophylaxis used across the study, with the highest rate of VTE in patients administered Apixaban (4.9%). The most common chemical prophylaxis used in the study was Enoxaparin (27.19%) followed by Dalteparin (20.38%). There was no evidence of a decrease in VTE if mechanical prophylaxis was used. The study identified specific diagnosis with increased risk of VTE and comorbidities

Structural Validation of the Manchester-Oxford Foot Questionnaire (MOxFQ) for use in Foot and Ankle Surgery

Category: Other Introduction/Purpose: The Manchester-Oxford Foot Questionnaire (MOxFQ) is a condition specific patient reported outcome measure (PROM) for foot and ankle surgery. It consists of 16 items across three subscales measuring distinct, but related traits: walking/standing ability, pain, and social interaction. Although it is the most used foot and ankle PROM in the UK, initial MOxFQ validation involved analysis of only 100 individuals undergoing hallux valgus surgery. This project aimed to establish whether an individual’s response to the MOxFQ varies with anatomical region of disease (measurement invariance), and to explore structural validity of the factor structure (subscale items) of the MOxFQ. Methods: This was a single-centre, prospective cohort study involving 6640 patients (mean age 52, range 10-90 years) presenting with a wide range of foot and ankle pathologies between 2013 and 2021. Firstly, to assess whether the MOxFQ responses vary by anatomical region of foot and ankle disease, we performed multi-group confirmatory factor analysis. Secondly, to assess the structural validity of the subscale items, exploratory and confirmatory factor analyses were performed. Results: Measurement invariance by pathology was confirmed suggesting the same model can be used across all foot and ankle anatomical regions. Exploratory factor analysis demonstrated a 2-3 factor model, and suggested that item 13 (inability to carry out my work/everyday activities) and item 14 (inability to undertake social/recreational activities) loaded more positively onto the walking/standing subscale than their original social interaction subscale. Conclusion: This large-cohort study supports the current widespread use of the MOxFQ across a broad range of foot and ankle pathologies. Items 13 and 14 might be better moved from the “social interaction” to the “walking/standing” subscale and this may have future implications for deriving/analysing subscale scores

Talar Neck Rotation Angle in Adults with Clubfoot Deformity: Observed Values and Intra- and Inter- Observer Reliability using Weightbearing CT

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Adults presenting with symptomatic clubfoot represent a challenging cohort of patients. An appreciation of the location and degree of deformities is essential for management. Talar anatomy is often abnormal with varus within the talar neck, however, there are few reproducible methods which quantify talar neck deformity in adults. We describe a technique of assessing talar neck deformity, and report on observed values and intra- / inter-observer reliability. Methods: This was a single-centre, retrospective study including 96 feet from 56 adult patients with clubfeet (82 feet had clubfoot deformity, 14 were normal). Mean age was 34.3±16.9 years and 31 (55.3%) were male. Weight-bearing CT scans captured as part of routine clinical care were analysed. Image reformats were oriented parallel to the long axis of the talus in the sagittal plane. In the corresponding axial plane two lines were drawn (on separate slices): 1) a line perpendicular to the intermalleolar axis, 2) a line connecting the midpoints of the talar head and narrowest part of the talar neck. The talar neck rotation angle (TNR angle) was the angle formed between these lines. Intraclass correlation coefficients (ICC) were performed for intra- and inter-observer reliability. Results: Mean TNR angle in clubfeet was 27.6±12.2 degrees (95%CI = 25.0 to 30.2 degrees). Mean TNR angle in normal feet was 18.7±5.1 degrees (95%CI = 16.0 to 21.4 degrees) (p < 0.001). The ICC for clubfeet was 0.944 (95%CI = 0.913 to 0.964) for intra- observer agreement, and 0.896 (95%CI = 0.837 to 0.932) for inter-observer agreement. Conclusion: This measurement technique demonstrated excellent intra- and inter-observer agreement. It also demonstrated that compared to normal feet, clubfeet had about 9 degrees of increased varus angulation of the talar neck. This technique and data may be used for future research into clubfoot deformity and in planning treatment

One Year Outcomes of the H-AMIC Procedure for Osteochondral Lesions of the Talus

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Osteochondral lesions of the talus (OLTs) present a challenging clinical problem. Hyaluronic acid assisted autologous membrane-induced chondrogenesis (H-AMIC) is a technique where a polyglycolic acid and hyaluronin membrane scaffold (Chondrotissue ® ) is affixed over an area of talar bone marrow stimulation. Our study aims to assess the efficacy of this technique. Methods: We undertook a prospective study on consecutive adult patients at our unit who had H-AMIC procedures between January 2020 and November 2021 to treat single, symptomatic OLTs, >1.5cm 2 , refractory to previous management. Data was collected on patient reported outcomes (MOxFQ, EQ5D, satisfaction), ankle range of movement, and complications at 1-year post-surgery. Fifteen patients were included in this study with a mean age of 33.8±20.9 years. Mean duration of symptoms was 7.9±5.2 years, with a mean of 1.5 previous procedures (range 0 to 3). All patients had osteotomies to gain access to the OLT (13 medial malleolar, 2 fibular). Results: Mean improvements greater than the minimum clinically important difference (MCID) were seen in MOxFQ-Pain (61.7±26.1 to 48.3±21.8, p=0.112), MOxFQ-Walking (64.6±21.8 to 46.6±23.9, p=0.067), MOxFQ-Social (63.67±22.5 to 41.8±29.2, p=0.055), although none reached statistical significance. No difference was seen in EQ5D. Overall improvements were seen in MOxFQ-Pain in 58.3%, MOxFQ-Walking in 75%, and MOxFQ-Social in 83.3% of patients. Overall, 11 patients (73.3%) were satisfied with the procedure. Patients displayed improvement in plantarflexion from 33.1±5.5 to 42.0±7.9 degrees (p=0.002) and no change to dorsiflexion. There were no complications. Conclusion: The H-AMIC procedure is a promising and safe option for larger osteochondral lesions of the talus. Early results suggest improved range of motion despite osteotomy and clinically (but not statistically) significant improvement in function in a group of patients with longstanding symptoms and previous failed surgery. Larger, adequately powered cohorts may establish statistical efficacy of this technique compared with alternative techniques

Opposing Flanks vs Parallel Flanks – the Influence of Headless Screw Design on Compression and Pull- Out Resistance

Category: Basic Sciences/Biologics; Basic Sciences/Biologics Introduction/Purpose: Screws generate and maintain compression against distracting forces when performing osteotomy or fusion surgery. Headless screws with opposing flank angles (OFA) between the threads of the head and shaft are purported to achieve better compression. The purpose of this study was to compare OFA designs against traditional parallel flank angle (PFA) headless screws and headed screws to determine differences in compression and pull-out resistance (POR). Methods: In this biomechanical in-vitro study, four screw designs were compared: headless screws with OFA (Screw_A and Screw_B), headless screws with PFA (Screw_C), and headed screws (Screw_D). All screws were 4.0x50mm partially threaded cannulated screws. Screw_B had a 1.4mm shorter head length and 0.5mm narrower head thread diameter than Screw_A and Screw_C, which were similar. A custom apparatus was designed for measuring compression and POR. Osteotomies were created on synthetic bone blocks (density 0.32g/cm3) simulating cancellous bone. Screws were inserted perpendicular to osteotomies in accordance with manufacturer guidance and maximum compression recorded. Increasing distracting forces were then applied to the blocks until the screws pulled out. For each screw type, five screws were tested. Results: There was no significant difference in maximum compression between screw designs: Screw_A=38.7N±14.2N, Screw_B=48.7N±15.6N, Screw_C=51.9N±36.4N, Screw_D=32.0N±9.2N; p=0.921. When assessing POR, all screws failed at the head-bone interface (screw heads subsided into block). Pull-out forces significantly differed between all groups: Screw_A=466N±29.0N, Screw_B=310N±22.0N, Screw_C=399N±46.0N, Screw_D=183N±12.9N; p< 0.001 (ANOVA). Screw_Ahad the highest POR but the other OFA design (Screw_B) had significantly lower POR. Conclusion: Screw design, whether headless (OFA or PFA) or headed did not appear to influence compression generated. However, headed screws had significantly lower POR than headless designs. Within headless designs, OFA may increase POR, but other screw head features (number / diameter of threads) had an apparently greater influence than flank angle